refs.con commit subtree: make "all" default target of Makefile (960160b)
   1#include "cache.h"
   2#include "refs.h"
   3#include "object.h"
   4#include "tag.h"
   5#include "dir.h"
   6#include "string-list.h"
   7
   8/*
   9 * How to handle various characters in refnames:
  10 * This table is used by both the SIMD and non-SIMD code.  It has
  11 * some cases that are only useful for the SIMD; these are handled
  12 * equivalently to the listed disposition in the non-SIMD code.
  13 * 0: An acceptable character for refs
  14 * 1: @, look for a following { to reject @{ in refs (SIMD or = 0)
  15 * 2: \0: End-of-component and string
  16 * 3: /: End-of-component (SIMD or = 2)
  17 * 4: ., look for a preceding . to reject .. in refs
  18 * 5: {, look for a preceding @ to reject @{ in refs
  19 * 6: *, usually a bad character except, once as a wildcard (SIMD or = 7)
  20 * 7: A bad character except * (see check_refname_component below)
  21 */
  22static unsigned char refname_disposition[256] = {
  23        2, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
  24        7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
  25        7, 0, 0, 0, 0, 0, 0, 0, 0, 0, 6, 0, 0, 0, 4, 3,
  26        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 7, 0, 0, 0, 0, 7,
  27        1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  28        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 7, 7, 0, 7, 0,
  29        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  30        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 5, 0, 0, 7, 7
  31};
  32
  33/*
  34 * Try to read one refname component from the front of refname.
  35 * Return the length of the component found, or -1 if the component is
  36 * not legal.  It is legal if it is something reasonable to have under
  37 * ".git/refs/"; We do not like it if:
  38 *
  39 * - any path component of it begins with ".", or
  40 * - it has double dots "..", or
  41 * - it has ASCII control character, "~", "^", ":" or SP, anywhere, or
  42 * - it has pattern-matching notation "*", "?", "[", anywhere, or
  43 * - it ends with a "/", or
  44 * - it ends with ".lock", or
  45 * - it contains a "\" (backslash)
  46 */
  47static int check_refname_component(const char *refname, int flags)
  48{
  49        const char *cp;
  50        char last = '\0';
  51
  52        for (cp = refname; ; cp++) {
  53                int ch = *cp & 255;
  54                unsigned char disp = refname_disposition[ch];
  55                switch (disp) {
  56                case 2: /* fall-through */
  57                case 3:
  58                        goto out;
  59                case 4:
  60                        if (last == '.')
  61                                return -1; /* Refname contains "..". */
  62                        break;
  63                case 5:
  64                        if (last == '@')
  65                                return -1; /* Refname contains "@{". */
  66                        break;
  67                case 6: /* fall-through */
  68                case 7:
  69                        return -1;
  70                }
  71                last = ch;
  72        }
  73out:
  74        if (cp == refname)
  75                return 0; /* Component has zero length. */
  76        if (refname[0] == '.') {
  77                if (!(flags & REFNAME_DOT_COMPONENT))
  78                        return -1; /* Component starts with '.'. */
  79                /*
  80                 * Even if leading dots are allowed, don't allow "."
  81                 * as a component (".." is prevented by a rule above).
  82                 */
  83                if (refname[1] == '\0')
  84                        return -1; /* Component equals ".". */
  85        }
  86        if (cp - refname >= 5 && !memcmp(cp - 5, ".lock", 5))
  87                return -1; /* Refname ends with ".lock". */
  88        return cp - refname;
  89}
  90
  91static int check_refname_format_bytewise(const char *refname, int flags)
  92{
  93        int component_len, component_count = 0;
  94
  95        if (!strcmp(refname, "@"))
  96                /* Refname is a single character '@'. */
  97                return -1;
  98
  99        while (1) {
 100                /* We are at the start of a path component. */
 101                component_len = check_refname_component(refname, flags);
 102                if (component_len <= 0) {
 103                        if ((flags & REFNAME_REFSPEC_PATTERN) &&
 104                                        refname[0] == '*' &&
 105                                        (refname[1] == '\0' || refname[1] == '/')) {
 106                                /* Accept one wildcard as a full refname component. */
 107                                flags &= ~REFNAME_REFSPEC_PATTERN;
 108                                component_len = 1;
 109                        } else {
 110                                return -1;
 111                        }
 112                }
 113                component_count++;
 114                if (refname[component_len] == '\0')
 115                        break;
 116                /* Skip to next component. */
 117                refname += component_len + 1;
 118        }
 119
 120        if (refname[component_len - 1] == '.')
 121                return -1; /* Refname ends with '.'. */
 122        if (!(flags & REFNAME_ALLOW_ONELEVEL) && component_count < 2)
 123                return -1; /* Refname has only one component. */
 124        return 0;
 125}
 126
 127#if defined(__GNUC__) && defined(__x86_64__)
 128#define SSE_VECTOR_BYTES 16
 129
 130/* Vectorized version of check_refname_format. */
 131int check_refname_format(const char *refname, int flags)
 132{
 133        const char *cp = refname;
 134
 135        const __m128i dot = _mm_set1_epi8('.');
 136        const __m128i at = _mm_set1_epi8('@');
 137        const __m128i curly = _mm_set1_epi8('{');
 138        const __m128i slash = _mm_set1_epi8('/');
 139        const __m128i zero = _mm_set1_epi8('\000');
 140        const __m128i el = _mm_set1_epi8('l');
 141
 142        /* below '*', all characters are forbidden or rare */
 143        const __m128i star_ub = _mm_set1_epi8('*' + 1);
 144
 145        const __m128i colon = _mm_set1_epi8(':');
 146        const __m128i question = _mm_set1_epi8('?');
 147
 148        /* '['..'^' contains 4 characters: 3 forbidden and 1 rare */
 149        const __m128i bracket_lb = _mm_set1_epi8('[' - 1);
 150        const __m128i caret_ub = _mm_set1_epi8('^' + 1);
 151
 152        /* '~' and above are forbidden */
 153        const __m128i tilde_lb = _mm_set1_epi8('~' - 1);
 154
 155        int component_count = 0;
 156        int orig_flags = flags;
 157
 158        if (refname[0] == 0 || refname[0] == '/') {
 159                /* entirely empty ref or initial ref component */
 160                return -1;
 161        }
 162
 163        /*
 164         * Initial ref component of '.'; below we look for /. so we'll
 165         * miss this.
 166         */
 167        if (refname[0] == '.') {
 168                if (refname[1] == '/' || refname[1] == '\0')
 169                        return -1;
 170                if (!(flags & REFNAME_DOT_COMPONENT))
 171                        return -1;
 172        }
 173        while(1) {
 174                __m128i tmp, tmp1, result;
 175                uint64_t mask;
 176
 177                if ((uintptr_t) cp % PAGE_SIZE > PAGE_SIZE - SSE_VECTOR_BYTES  - 1)
 178                        /*
 179                         * End-of-page; fall back to slow method for
 180                         * this entire ref.
 181                         */
 182                        return check_refname_format_bytewise(refname, orig_flags);
 183
 184                tmp = _mm_loadu_si128((__m128i *)cp);
 185                tmp1 = _mm_loadu_si128((__m128i *)(cp + 1));
 186
 187                /*
 188                 * This range (note the lt) contains some
 189                 * permissible-but-rare characters (including all
 190                 * characters >= 128), which we handle later.  It also
 191                 * includes \000.
 192                 */
 193                result = _mm_cmplt_epi8(tmp, star_ub);
 194
 195                result = _mm_or_si128(result, _mm_cmpeq_epi8(tmp, question));
 196                result = _mm_or_si128(result, _mm_cmpeq_epi8(tmp, colon));
 197
 198                /* This range contains the permissible ] as bycatch */
 199                result = _mm_or_si128(result, _mm_and_si128(
 200                                              _mm_cmpgt_epi8(tmp, bracket_lb),
 201                                              _mm_cmplt_epi8(tmp, caret_ub)));
 202
 203                result = _mm_or_si128(result, _mm_cmpgt_epi8(tmp, tilde_lb));
 204
 205                /* .. */
 206                result = _mm_or_si128(result, _mm_and_si128(
 207                                              _mm_cmpeq_epi8(tmp, dot),
 208                                              _mm_cmpeq_epi8(tmp1, dot)));
 209                /* @{ */
 210                result = _mm_or_si128(result, _mm_and_si128(
 211                                              _mm_cmpeq_epi8(tmp, at),
 212                                              _mm_cmpeq_epi8(tmp1, curly)));
 213                /* // */
 214                result = _mm_or_si128(result, _mm_and_si128(
 215                                              _mm_cmpeq_epi8(tmp, slash),
 216                                              _mm_cmpeq_epi8(tmp1, slash)));
 217                /* trailing / */
 218                result = _mm_or_si128(result, _mm_and_si128(
 219                                              _mm_cmpeq_epi8(tmp, slash),
 220                                              _mm_cmpeq_epi8(tmp1, zero)));
 221                /* .l, beginning of .lock */
 222                result = _mm_or_si128(result, _mm_and_si128(
 223                                              _mm_cmpeq_epi8(tmp, dot),
 224                                              _mm_cmpeq_epi8(tmp1, el)));
 225                /*
 226                 * Even though /. is not necessarily an error, we flag
 227                 * it anyway. If we find it, we'll check if it's valid
 228                 * and if so we'll advance just past it.
 229                 */
 230                result = _mm_or_si128(result, _mm_and_si128(
 231                                              _mm_cmpeq_epi8(tmp, slash),
 232                                              _mm_cmpeq_epi8(tmp1, dot)));
 233
 234                mask = _mm_movemask_epi8(result);
 235                if (mask) {
 236                        /*
 237                         * We've found either end-of-string, or some
 238                         * probably-bad character or substring.
 239                         */
 240                        int i = __builtin_ctz(mask);
 241                        switch (refname_disposition[cp[i] & 255]) {
 242                        case 0: /* fall-through */
 243                        case 5:
 244                                /*
 245                                 * bycatch: a good character that's in
 246                                 * one of the ranges of mostly-forbidden
 247                                 * characters
 248                                 */
 249                                cp += i + 1;
 250                                break;
 251                        case 1:
 252                                if (cp[i + 1] == '{')
 253                                        return -1;
 254                                cp += i + 1;
 255                                break;
 256                        case 2:
 257                                if (!(flags & REFNAME_ALLOW_ONELEVEL)
 258                                    && !component_count && !strchr(refname, '/'))
 259                                        /* Refname has only one component. */
 260                                        return -1;
 261                                return 0;
 262                        case 3:
 263                                component_count ++;
 264                                /*
 265                                 * Even if leading dots are allowed, don't
 266                                 * allow "." as a component (".." is
 267                                 * prevented by case 4 below).
 268                                 */
 269                                if (cp[i + 1] == '.') {
 270                                        if (cp[i + 2] == '\0')
 271                                                return -1;
 272                                        if (flags & REFNAME_DOT_COMPONENT) {
 273                                                /* skip to just after the /. */
 274                                                cp += i + 2;
 275                                                break;
 276                                        }
 277                                        return -1;
 278                                } else if (cp[i + 1] == '/' || cp[i + 1] == '\0')
 279                                        return -1;
 280                                break;
 281                        case 4:
 282                                if (cp[i + 1] == '.' || cp[i + 1] == '\0')
 283                                        return -1;
 284                                /* .lock as end-of-component or end-of-string */
 285                                if ((!strncmp(cp + i, ".lock", 5))
 286                                    && (cp[i + 5] == '/' || cp[i + 5] == 0))
 287                                        return -1;
 288                                cp += 1;
 289                                break;
 290                        case 6:
 291                                if (((cp == refname + i) || cp[i - 1] == '/')
 292                                    && (cp[i + 1] == '/' || cp[i + 1] == 0))
 293                                        if (flags & REFNAME_REFSPEC_PATTERN) {
 294                                                flags &= ~REFNAME_REFSPEC_PATTERN;
 295                                                /* restart after the * */
 296                                                cp += i + 1;
 297                                                continue;
 298                                        }
 299                                /* fall-through */
 300                        case 7:
 301                                return -1;
 302                        }
 303                } else
 304                        cp += SSE_VECTOR_BYTES;
 305        }
 306}
 307
 308#else
 309
 310int check_refname_format (const char *refname, int flags)
 311{
 312        return check_refname_format_bytewise(refname, flags);
 313}
 314
 315#endif
 316
 317struct ref_entry;
 318
 319/*
 320 * Information used (along with the information in ref_entry) to
 321 * describe a single cached reference.  This data structure only
 322 * occurs embedded in a union in struct ref_entry, and only when
 323 * (ref_entry->flag & REF_DIR) is zero.
 324 */
 325struct ref_value {
 326        /*
 327         * The name of the object to which this reference resolves
 328         * (which may be a tag object).  If REF_ISBROKEN, this is
 329         * null.  If REF_ISSYMREF, then this is the name of the object
 330         * referred to by the last reference in the symlink chain.
 331         */
 332        unsigned char sha1[20];
 333
 334        /*
 335         * If REF_KNOWS_PEELED, then this field holds the peeled value
 336         * of this reference, or null if the reference is known not to
 337         * be peelable.  See the documentation for peel_ref() for an
 338         * exact definition of "peelable".
 339         */
 340        unsigned char peeled[20];
 341};
 342
 343struct ref_cache;
 344
 345/*
 346 * Information used (along with the information in ref_entry) to
 347 * describe a level in the hierarchy of references.  This data
 348 * structure only occurs embedded in a union in struct ref_entry, and
 349 * only when (ref_entry.flag & REF_DIR) is set.  In that case,
 350 * (ref_entry.flag & REF_INCOMPLETE) determines whether the references
 351 * in the directory have already been read:
 352 *
 353 *     (ref_entry.flag & REF_INCOMPLETE) unset -- a directory of loose
 354 *         or packed references, already read.
 355 *
 356 *     (ref_entry.flag & REF_INCOMPLETE) set -- a directory of loose
 357 *         references that hasn't been read yet (nor has any of its
 358 *         subdirectories).
 359 *
 360 * Entries within a directory are stored within a growable array of
 361 * pointers to ref_entries (entries, nr, alloc).  Entries 0 <= i <
 362 * sorted are sorted by their component name in strcmp() order and the
 363 * remaining entries are unsorted.
 364 *
 365 * Loose references are read lazily, one directory at a time.  When a
 366 * directory of loose references is read, then all of the references
 367 * in that directory are stored, and REF_INCOMPLETE stubs are created
 368 * for any subdirectories, but the subdirectories themselves are not
 369 * read.  The reading is triggered by get_ref_dir().
 370 */
 371struct ref_dir {
 372        int nr, alloc;
 373
 374        /*
 375         * Entries with index 0 <= i < sorted are sorted by name.  New
 376         * entries are appended to the list unsorted, and are sorted
 377         * only when required; thus we avoid the need to sort the list
 378         * after the addition of every reference.
 379         */
 380        int sorted;
 381
 382        /* A pointer to the ref_cache that contains this ref_dir. */
 383        struct ref_cache *ref_cache;
 384
 385        struct ref_entry **entries;
 386};
 387
 388/*
 389 * Bit values for ref_entry::flag.  REF_ISSYMREF=0x01,
 390 * REF_ISPACKED=0x02, and REF_ISBROKEN=0x04 are public values; see
 391 * refs.h.
 392 */
 393
 394/*
 395 * The field ref_entry->u.value.peeled of this value entry contains
 396 * the correct peeled value for the reference, which might be
 397 * null_sha1 if the reference is not a tag or if it is broken.
 398 */
 399#define REF_KNOWS_PEELED 0x08
 400
 401/* ref_entry represents a directory of references */
 402#define REF_DIR 0x10
 403
 404/*
 405 * Entry has not yet been read from disk (used only for REF_DIR
 406 * entries representing loose references)
 407 */
 408#define REF_INCOMPLETE 0x20
 409
 410/*
 411 * A ref_entry represents either a reference or a "subdirectory" of
 412 * references.
 413 *
 414 * Each directory in the reference namespace is represented by a
 415 * ref_entry with (flags & REF_DIR) set and containing a subdir member
 416 * that holds the entries in that directory that have been read so
 417 * far.  If (flags & REF_INCOMPLETE) is set, then the directory and
 418 * its subdirectories haven't been read yet.  REF_INCOMPLETE is only
 419 * used for loose reference directories.
 420 *
 421 * References are represented by a ref_entry with (flags & REF_DIR)
 422 * unset and a value member that describes the reference's value.  The
 423 * flag member is at the ref_entry level, but it is also needed to
 424 * interpret the contents of the value field (in other words, a
 425 * ref_value object is not very much use without the enclosing
 426 * ref_entry).
 427 *
 428 * Reference names cannot end with slash and directories' names are
 429 * always stored with a trailing slash (except for the top-level
 430 * directory, which is always denoted by "").  This has two nice
 431 * consequences: (1) when the entries in each subdir are sorted
 432 * lexicographically by name (as they usually are), the references in
 433 * a whole tree can be generated in lexicographic order by traversing
 434 * the tree in left-to-right, depth-first order; (2) the names of
 435 * references and subdirectories cannot conflict, and therefore the
 436 * presence of an empty subdirectory does not block the creation of a
 437 * similarly-named reference.  (The fact that reference names with the
 438 * same leading components can conflict *with each other* is a
 439 * separate issue that is regulated by is_refname_available().)
 440 *
 441 * Please note that the name field contains the fully-qualified
 442 * reference (or subdirectory) name.  Space could be saved by only
 443 * storing the relative names.  But that would require the full names
 444 * to be generated on the fly when iterating in do_for_each_ref(), and
 445 * would break callback functions, who have always been able to assume
 446 * that the name strings that they are passed will not be freed during
 447 * the iteration.
 448 */
 449struct ref_entry {
 450        unsigned char flag; /* ISSYMREF? ISPACKED? */
 451        union {
 452                struct ref_value value; /* if not (flags&REF_DIR) */
 453                struct ref_dir subdir; /* if (flags&REF_DIR) */
 454        } u;
 455        /*
 456         * The full name of the reference (e.g., "refs/heads/master")
 457         * or the full name of the directory with a trailing slash
 458         * (e.g., "refs/heads/"):
 459         */
 460        char name[FLEX_ARRAY];
 461};
 462
 463static void read_loose_refs(const char *dirname, struct ref_dir *dir);
 464
 465static struct ref_dir *get_ref_dir(struct ref_entry *entry)
 466{
 467        struct ref_dir *dir;
 468        assert(entry->flag & REF_DIR);
 469        dir = &entry->u.subdir;
 470        if (entry->flag & REF_INCOMPLETE) {
 471                read_loose_refs(entry->name, dir);
 472                entry->flag &= ~REF_INCOMPLETE;
 473        }
 474        return dir;
 475}
 476
 477static struct ref_entry *create_ref_entry(const char *refname,
 478                                          const unsigned char *sha1, int flag,
 479                                          int check_name)
 480{
 481        int len;
 482        struct ref_entry *ref;
 483
 484        if (check_name &&
 485            check_refname_format(refname, REFNAME_ALLOW_ONELEVEL|REFNAME_DOT_COMPONENT))
 486                die("Reference has invalid format: '%s'", refname);
 487        len = strlen(refname) + 1;
 488        ref = xmalloc(sizeof(struct ref_entry) + len);
 489        hashcpy(ref->u.value.sha1, sha1);
 490        hashclr(ref->u.value.peeled);
 491        memcpy(ref->name, refname, len);
 492        ref->flag = flag;
 493        return ref;
 494}
 495
 496static void clear_ref_dir(struct ref_dir *dir);
 497
 498static void free_ref_entry(struct ref_entry *entry)
 499{
 500        if (entry->flag & REF_DIR) {
 501                /*
 502                 * Do not use get_ref_dir() here, as that might
 503                 * trigger the reading of loose refs.
 504                 */
 505                clear_ref_dir(&entry->u.subdir);
 506        }
 507        free(entry);
 508}
 509
 510/*
 511 * Add a ref_entry to the end of dir (unsorted).  Entry is always
 512 * stored directly in dir; no recursion into subdirectories is
 513 * done.
 514 */
 515static void add_entry_to_dir(struct ref_dir *dir, struct ref_entry *entry)
 516{
 517        ALLOC_GROW(dir->entries, dir->nr + 1, dir->alloc);
 518        dir->entries[dir->nr++] = entry;
 519        /* optimize for the case that entries are added in order */
 520        if (dir->nr == 1 ||
 521            (dir->nr == dir->sorted + 1 &&
 522             strcmp(dir->entries[dir->nr - 2]->name,
 523                    dir->entries[dir->nr - 1]->name) < 0))
 524                dir->sorted = dir->nr;
 525}
 526
 527/*
 528 * Clear and free all entries in dir, recursively.
 529 */
 530static void clear_ref_dir(struct ref_dir *dir)
 531{
 532        int i;
 533        for (i = 0; i < dir->nr; i++)
 534                free_ref_entry(dir->entries[i]);
 535        free(dir->entries);
 536        dir->sorted = dir->nr = dir->alloc = 0;
 537        dir->entries = NULL;
 538}
 539
 540/*
 541 * Create a struct ref_entry object for the specified dirname.
 542 * dirname is the name of the directory with a trailing slash (e.g.,
 543 * "refs/heads/") or "" for the top-level directory.
 544 */
 545static struct ref_entry *create_dir_entry(struct ref_cache *ref_cache,
 546                                          const char *dirname, size_t len,
 547                                          int incomplete)
 548{
 549        struct ref_entry *direntry;
 550        direntry = xcalloc(1, sizeof(struct ref_entry) + len + 1);
 551        memcpy(direntry->name, dirname, len);
 552        direntry->name[len] = '\0';
 553        direntry->u.subdir.ref_cache = ref_cache;
 554        direntry->flag = REF_DIR | (incomplete ? REF_INCOMPLETE : 0);
 555        return direntry;
 556}
 557
 558static int ref_entry_cmp(const void *a, const void *b)
 559{
 560        struct ref_entry *one = *(struct ref_entry **)a;
 561        struct ref_entry *two = *(struct ref_entry **)b;
 562        return strcmp(one->name, two->name);
 563}
 564
 565static void sort_ref_dir(struct ref_dir *dir);
 566
 567struct string_slice {
 568        size_t len;
 569        const char *str;
 570};
 571
 572static int ref_entry_cmp_sslice(const void *key_, const void *ent_)
 573{
 574        const struct string_slice *key = key_;
 575        const struct ref_entry *ent = *(const struct ref_entry * const *)ent_;
 576        int cmp = strncmp(key->str, ent->name, key->len);
 577        if (cmp)
 578                return cmp;
 579        return '\0' - (unsigned char)ent->name[key->len];
 580}
 581
 582/*
 583 * Return the index of the entry with the given refname from the
 584 * ref_dir (non-recursively), sorting dir if necessary.  Return -1 if
 585 * no such entry is found.  dir must already be complete.
 586 */
 587static int search_ref_dir(struct ref_dir *dir, const char *refname, size_t len)
 588{
 589        struct ref_entry **r;
 590        struct string_slice key;
 591
 592        if (refname == NULL || !dir->nr)
 593                return -1;
 594
 595        sort_ref_dir(dir);
 596        key.len = len;
 597        key.str = refname;
 598        r = bsearch(&key, dir->entries, dir->nr, sizeof(*dir->entries),
 599                    ref_entry_cmp_sslice);
 600
 601        if (r == NULL)
 602                return -1;
 603
 604        return r - dir->entries;
 605}
 606
 607/*
 608 * Search for a directory entry directly within dir (without
 609 * recursing).  Sort dir if necessary.  subdirname must be a directory
 610 * name (i.e., end in '/').  If mkdir is set, then create the
 611 * directory if it is missing; otherwise, return NULL if the desired
 612 * directory cannot be found.  dir must already be complete.
 613 */
 614static struct ref_dir *search_for_subdir(struct ref_dir *dir,
 615                                         const char *subdirname, size_t len,
 616                                         int mkdir)
 617{
 618        int entry_index = search_ref_dir(dir, subdirname, len);
 619        struct ref_entry *entry;
 620        if (entry_index == -1) {
 621                if (!mkdir)
 622                        return NULL;
 623                /*
 624                 * Since dir is complete, the absence of a subdir
 625                 * means that the subdir really doesn't exist;
 626                 * therefore, create an empty record for it but mark
 627                 * the record complete.
 628                 */
 629                entry = create_dir_entry(dir->ref_cache, subdirname, len, 0);
 630                add_entry_to_dir(dir, entry);
 631        } else {
 632                entry = dir->entries[entry_index];
 633        }
 634        return get_ref_dir(entry);
 635}
 636
 637/*
 638 * If refname is a reference name, find the ref_dir within the dir
 639 * tree that should hold refname.  If refname is a directory name
 640 * (i.e., ends in '/'), then return that ref_dir itself.  dir must
 641 * represent the top-level directory and must already be complete.
 642 * Sort ref_dirs and recurse into subdirectories as necessary.  If
 643 * mkdir is set, then create any missing directories; otherwise,
 644 * return NULL if the desired directory cannot be found.
 645 */
 646static struct ref_dir *find_containing_dir(struct ref_dir *dir,
 647                                           const char *refname, int mkdir)
 648{
 649        const char *slash;
 650        for (slash = strchr(refname, '/'); slash; slash = strchr(slash + 1, '/')) {
 651                size_t dirnamelen = slash - refname + 1;
 652                struct ref_dir *subdir;
 653                subdir = search_for_subdir(dir, refname, dirnamelen, mkdir);
 654                if (!subdir) {
 655                        dir = NULL;
 656                        break;
 657                }
 658                dir = subdir;
 659        }
 660
 661        return dir;
 662}
 663
 664/*
 665 * Find the value entry with the given name in dir, sorting ref_dirs
 666 * and recursing into subdirectories as necessary.  If the name is not
 667 * found or it corresponds to a directory entry, return NULL.
 668 */
 669static struct ref_entry *find_ref(struct ref_dir *dir, const char *refname)
 670{
 671        int entry_index;
 672        struct ref_entry *entry;
 673        dir = find_containing_dir(dir, refname, 0);
 674        if (!dir)
 675                return NULL;
 676        entry_index = search_ref_dir(dir, refname, strlen(refname));
 677        if (entry_index == -1)
 678                return NULL;
 679        entry = dir->entries[entry_index];
 680        return (entry->flag & REF_DIR) ? NULL : entry;
 681}
 682
 683/*
 684 * Remove the entry with the given name from dir, recursing into
 685 * subdirectories as necessary.  If refname is the name of a directory
 686 * (i.e., ends with '/'), then remove the directory and its contents.
 687 * If the removal was successful, return the number of entries
 688 * remaining in the directory entry that contained the deleted entry.
 689 * If the name was not found, return -1.  Please note that this
 690 * function only deletes the entry from the cache; it does not delete
 691 * it from the filesystem or ensure that other cache entries (which
 692 * might be symbolic references to the removed entry) are updated.
 693 * Nor does it remove any containing dir entries that might be made
 694 * empty by the removal.  dir must represent the top-level directory
 695 * and must already be complete.
 696 */
 697static int remove_entry(struct ref_dir *dir, const char *refname)
 698{
 699        int refname_len = strlen(refname);
 700        int entry_index;
 701        struct ref_entry *entry;
 702        int is_dir = refname[refname_len - 1] == '/';
 703        if (is_dir) {
 704                /*
 705                 * refname represents a reference directory.  Remove
 706                 * the trailing slash; otherwise we will get the
 707                 * directory *representing* refname rather than the
 708                 * one *containing* it.
 709                 */
 710                char *dirname = xmemdupz(refname, refname_len - 1);
 711                dir = find_containing_dir(dir, dirname, 0);
 712                free(dirname);
 713        } else {
 714                dir = find_containing_dir(dir, refname, 0);
 715        }
 716        if (!dir)
 717                return -1;
 718        entry_index = search_ref_dir(dir, refname, refname_len);
 719        if (entry_index == -1)
 720                return -1;
 721        entry = dir->entries[entry_index];
 722
 723        memmove(&dir->entries[entry_index],
 724                &dir->entries[entry_index + 1],
 725                (dir->nr - entry_index - 1) * sizeof(*dir->entries)
 726                );
 727        dir->nr--;
 728        if (dir->sorted > entry_index)
 729                dir->sorted--;
 730        free_ref_entry(entry);
 731        return dir->nr;
 732}
 733
 734/*
 735 * Add a ref_entry to the ref_dir (unsorted), recursing into
 736 * subdirectories as necessary.  dir must represent the top-level
 737 * directory.  Return 0 on success.
 738 */
 739static int add_ref(struct ref_dir *dir, struct ref_entry *ref)
 740{
 741        dir = find_containing_dir(dir, ref->name, 1);
 742        if (!dir)
 743                return -1;
 744        add_entry_to_dir(dir, ref);
 745        return 0;
 746}
 747
 748/*
 749 * Emit a warning and return true iff ref1 and ref2 have the same name
 750 * and the same sha1.  Die if they have the same name but different
 751 * sha1s.
 752 */
 753static int is_dup_ref(const struct ref_entry *ref1, const struct ref_entry *ref2)
 754{
 755        if (strcmp(ref1->name, ref2->name))
 756                return 0;
 757
 758        /* Duplicate name; make sure that they don't conflict: */
 759
 760        if ((ref1->flag & REF_DIR) || (ref2->flag & REF_DIR))
 761                /* This is impossible by construction */
 762                die("Reference directory conflict: %s", ref1->name);
 763
 764        if (hashcmp(ref1->u.value.sha1, ref2->u.value.sha1))
 765                die("Duplicated ref, and SHA1s don't match: %s", ref1->name);
 766
 767        warning("Duplicated ref: %s", ref1->name);
 768        return 1;
 769}
 770
 771/*
 772 * Sort the entries in dir non-recursively (if they are not already
 773 * sorted) and remove any duplicate entries.
 774 */
 775static void sort_ref_dir(struct ref_dir *dir)
 776{
 777        int i, j;
 778        struct ref_entry *last = NULL;
 779
 780        /*
 781         * This check also prevents passing a zero-length array to qsort(),
 782         * which is a problem on some platforms.
 783         */
 784        if (dir->sorted == dir->nr)
 785                return;
 786
 787        qsort(dir->entries, dir->nr, sizeof(*dir->entries), ref_entry_cmp);
 788
 789        /* Remove any duplicates: */
 790        for (i = 0, j = 0; j < dir->nr; j++) {
 791                struct ref_entry *entry = dir->entries[j];
 792                if (last && is_dup_ref(last, entry))
 793                        free_ref_entry(entry);
 794                else
 795                        last = dir->entries[i++] = entry;
 796        }
 797        dir->sorted = dir->nr = i;
 798}
 799
 800/* Include broken references in a do_for_each_ref*() iteration: */
 801#define DO_FOR_EACH_INCLUDE_BROKEN 0x01
 802
 803/*
 804 * Return true iff the reference described by entry can be resolved to
 805 * an object in the database.  Emit a warning if the referred-to
 806 * object does not exist.
 807 */
 808static int ref_resolves_to_object(struct ref_entry *entry)
 809{
 810        if (entry->flag & REF_ISBROKEN)
 811                return 0;
 812        if (!has_sha1_file(entry->u.value.sha1)) {
 813                error("%s does not point to a valid object!", entry->name);
 814                return 0;
 815        }
 816        return 1;
 817}
 818
 819/*
 820 * current_ref is a performance hack: when iterating over references
 821 * using the for_each_ref*() functions, current_ref is set to the
 822 * current reference's entry before calling the callback function.  If
 823 * the callback function calls peel_ref(), then peel_ref() first
 824 * checks whether the reference to be peeled is the current reference
 825 * (it usually is) and if so, returns that reference's peeled version
 826 * if it is available.  This avoids a refname lookup in a common case.
 827 */
 828static struct ref_entry *current_ref;
 829
 830typedef int each_ref_entry_fn(struct ref_entry *entry, void *cb_data);
 831
 832struct ref_entry_cb {
 833        const char *base;
 834        int trim;
 835        int flags;
 836        each_ref_fn *fn;
 837        void *cb_data;
 838};
 839
 840/*
 841 * Handle one reference in a do_for_each_ref*()-style iteration,
 842 * calling an each_ref_fn for each entry.
 843 */
 844static int do_one_ref(struct ref_entry *entry, void *cb_data)
 845{
 846        struct ref_entry_cb *data = cb_data;
 847        struct ref_entry *old_current_ref;
 848        int retval;
 849
 850        if (!starts_with(entry->name, data->base))
 851                return 0;
 852
 853        if (!(data->flags & DO_FOR_EACH_INCLUDE_BROKEN) &&
 854              !ref_resolves_to_object(entry))
 855                return 0;
 856
 857        /* Store the old value, in case this is a recursive call: */
 858        old_current_ref = current_ref;
 859        current_ref = entry;
 860        retval = data->fn(entry->name + data->trim, entry->u.value.sha1,
 861                          entry->flag, data->cb_data);
 862        current_ref = old_current_ref;
 863        return retval;
 864}
 865
 866/*
 867 * Call fn for each reference in dir that has index in the range
 868 * offset <= index < dir->nr.  Recurse into subdirectories that are in
 869 * that index range, sorting them before iterating.  This function
 870 * does not sort dir itself; it should be sorted beforehand.  fn is
 871 * called for all references, including broken ones.
 872 */
 873static int do_for_each_entry_in_dir(struct ref_dir *dir, int offset,
 874                                    each_ref_entry_fn fn, void *cb_data)
 875{
 876        int i;
 877        assert(dir->sorted == dir->nr);
 878        for (i = offset; i < dir->nr; i++) {
 879                struct ref_entry *entry = dir->entries[i];
 880                int retval;
 881                if (entry->flag & REF_DIR) {
 882                        struct ref_dir *subdir = get_ref_dir(entry);
 883                        sort_ref_dir(subdir);
 884                        retval = do_for_each_entry_in_dir(subdir, 0, fn, cb_data);
 885                } else {
 886                        retval = fn(entry, cb_data);
 887                }
 888                if (retval)
 889                        return retval;
 890        }
 891        return 0;
 892}
 893
 894/*
 895 * Call fn for each reference in the union of dir1 and dir2, in order
 896 * by refname.  Recurse into subdirectories.  If a value entry appears
 897 * in both dir1 and dir2, then only process the version that is in
 898 * dir2.  The input dirs must already be sorted, but subdirs will be
 899 * sorted as needed.  fn is called for all references, including
 900 * broken ones.
 901 */
 902static int do_for_each_entry_in_dirs(struct ref_dir *dir1,
 903                                     struct ref_dir *dir2,
 904                                     each_ref_entry_fn fn, void *cb_data)
 905{
 906        int retval;
 907        int i1 = 0, i2 = 0;
 908
 909        assert(dir1->sorted == dir1->nr);
 910        assert(dir2->sorted == dir2->nr);
 911        while (1) {
 912                struct ref_entry *e1, *e2;
 913                int cmp;
 914                if (i1 == dir1->nr) {
 915                        return do_for_each_entry_in_dir(dir2, i2, fn, cb_data);
 916                }
 917                if (i2 == dir2->nr) {
 918                        return do_for_each_entry_in_dir(dir1, i1, fn, cb_data);
 919                }
 920                e1 = dir1->entries[i1];
 921                e2 = dir2->entries[i2];
 922                cmp = strcmp(e1->name, e2->name);
 923                if (cmp == 0) {
 924                        if ((e1->flag & REF_DIR) && (e2->flag & REF_DIR)) {
 925                                /* Both are directories; descend them in parallel. */
 926                                struct ref_dir *subdir1 = get_ref_dir(e1);
 927                                struct ref_dir *subdir2 = get_ref_dir(e2);
 928                                sort_ref_dir(subdir1);
 929                                sort_ref_dir(subdir2);
 930                                retval = do_for_each_entry_in_dirs(
 931                                                subdir1, subdir2, fn, cb_data);
 932                                i1++;
 933                                i2++;
 934                        } else if (!(e1->flag & REF_DIR) && !(e2->flag & REF_DIR)) {
 935                                /* Both are references; ignore the one from dir1. */
 936                                retval = fn(e2, cb_data);
 937                                i1++;
 938                                i2++;
 939                        } else {
 940                                die("conflict between reference and directory: %s",
 941                                    e1->name);
 942                        }
 943                } else {
 944                        struct ref_entry *e;
 945                        if (cmp < 0) {
 946                                e = e1;
 947                                i1++;
 948                        } else {
 949                                e = e2;
 950                                i2++;
 951                        }
 952                        if (e->flag & REF_DIR) {
 953                                struct ref_dir *subdir = get_ref_dir(e);
 954                                sort_ref_dir(subdir);
 955                                retval = do_for_each_entry_in_dir(
 956                                                subdir, 0, fn, cb_data);
 957                        } else {
 958                                retval = fn(e, cb_data);
 959                        }
 960                }
 961                if (retval)
 962                        return retval;
 963        }
 964}
 965
 966/*
 967 * Load all of the refs from the dir into our in-memory cache. The hard work
 968 * of loading loose refs is done by get_ref_dir(), so we just need to recurse
 969 * through all of the sub-directories. We do not even need to care about
 970 * sorting, as traversal order does not matter to us.
 971 */
 972static void prime_ref_dir(struct ref_dir *dir)
 973{
 974        int i;
 975        for (i = 0; i < dir->nr; i++) {
 976                struct ref_entry *entry = dir->entries[i];
 977                if (entry->flag & REF_DIR)
 978                        prime_ref_dir(get_ref_dir(entry));
 979        }
 980}
 981/*
 982 * Return true iff refname1 and refname2 conflict with each other.
 983 * Two reference names conflict if one of them exactly matches the
 984 * leading components of the other; e.g., "foo/bar" conflicts with
 985 * both "foo" and with "foo/bar/baz" but not with "foo/bar" or
 986 * "foo/barbados".
 987 */
 988static int names_conflict(const char *refname1, const char *refname2)
 989{
 990        for (; *refname1 && *refname1 == *refname2; refname1++, refname2++)
 991                ;
 992        return (*refname1 == '\0' && *refname2 == '/')
 993                || (*refname1 == '/' && *refname2 == '\0');
 994}
 995
 996struct name_conflict_cb {
 997        const char *refname;
 998        const char *oldrefname;
 999        const char *conflicting_refname;
1000};
1001
1002static int name_conflict_fn(struct ref_entry *entry, void *cb_data)
1003{
1004        struct name_conflict_cb *data = (struct name_conflict_cb *)cb_data;
1005        if (data->oldrefname && !strcmp(data->oldrefname, entry->name))
1006                return 0;
1007        if (names_conflict(data->refname, entry->name)) {
1008                data->conflicting_refname = entry->name;
1009                return 1;
1010        }
1011        return 0;
1012}
1013
1014/*
1015 * Return true iff a reference named refname could be created without
1016 * conflicting with the name of an existing reference in dir.  If
1017 * oldrefname is non-NULL, ignore potential conflicts with oldrefname
1018 * (e.g., because oldrefname is scheduled for deletion in the same
1019 * operation).
1020 */
1021static int is_refname_available(const char *refname, const char *oldrefname,
1022                                struct ref_dir *dir)
1023{
1024        struct name_conflict_cb data;
1025        data.refname = refname;
1026        data.oldrefname = oldrefname;
1027        data.conflicting_refname = NULL;
1028
1029        sort_ref_dir(dir);
1030        if (do_for_each_entry_in_dir(dir, 0, name_conflict_fn, &data)) {
1031                error("'%s' exists; cannot create '%s'",
1032                      data.conflicting_refname, refname);
1033                return 0;
1034        }
1035        return 1;
1036}
1037
1038struct packed_ref_cache {
1039        struct ref_entry *root;
1040
1041        /*
1042         * Count of references to the data structure in this instance,
1043         * including the pointer from ref_cache::packed if any.  The
1044         * data will not be freed as long as the reference count is
1045         * nonzero.
1046         */
1047        unsigned int referrers;
1048
1049        /*
1050         * Iff the packed-refs file associated with this instance is
1051         * currently locked for writing, this points at the associated
1052         * lock (which is owned by somebody else).  The referrer count
1053         * is also incremented when the file is locked and decremented
1054         * when it is unlocked.
1055         */
1056        struct lock_file *lock;
1057
1058        /* The metadata from when this packed-refs cache was read */
1059        struct stat_validity validity;
1060};
1061
1062/*
1063 * Future: need to be in "struct repository"
1064 * when doing a full libification.
1065 */
1066static struct ref_cache {
1067        struct ref_cache *next;
1068        struct ref_entry *loose;
1069        struct packed_ref_cache *packed;
1070        /*
1071         * The submodule name, or "" for the main repo.  We allocate
1072         * length 1 rather than FLEX_ARRAY so that the main ref_cache
1073         * is initialized correctly.
1074         */
1075        char name[1];
1076} ref_cache, *submodule_ref_caches;
1077
1078/* Lock used for the main packed-refs file: */
1079static struct lock_file packlock;
1080
1081/*
1082 * Increment the reference count of *packed_refs.
1083 */
1084static void acquire_packed_ref_cache(struct packed_ref_cache *packed_refs)
1085{
1086        packed_refs->referrers++;
1087}
1088
1089/*
1090 * Decrease the reference count of *packed_refs.  If it goes to zero,
1091 * free *packed_refs and return true; otherwise return false.
1092 */
1093static int release_packed_ref_cache(struct packed_ref_cache *packed_refs)
1094{
1095        if (!--packed_refs->referrers) {
1096                free_ref_entry(packed_refs->root);
1097                stat_validity_clear(&packed_refs->validity);
1098                free(packed_refs);
1099                return 1;
1100        } else {
1101                return 0;
1102        }
1103}
1104
1105static void clear_packed_ref_cache(struct ref_cache *refs)
1106{
1107        if (refs->packed) {
1108                struct packed_ref_cache *packed_refs = refs->packed;
1109
1110                if (packed_refs->lock)
1111                        die("internal error: packed-ref cache cleared while locked");
1112                refs->packed = NULL;
1113                release_packed_ref_cache(packed_refs);
1114        }
1115}
1116
1117static void clear_loose_ref_cache(struct ref_cache *refs)
1118{
1119        if (refs->loose) {
1120                free_ref_entry(refs->loose);
1121                refs->loose = NULL;
1122        }
1123}
1124
1125static struct ref_cache *create_ref_cache(const char *submodule)
1126{
1127        int len;
1128        struct ref_cache *refs;
1129        if (!submodule)
1130                submodule = "";
1131        len = strlen(submodule) + 1;
1132        refs = xcalloc(1, sizeof(struct ref_cache) + len);
1133        memcpy(refs->name, submodule, len);
1134        return refs;
1135}
1136
1137/*
1138 * Return a pointer to a ref_cache for the specified submodule. For
1139 * the main repository, use submodule==NULL. The returned structure
1140 * will be allocated and initialized but not necessarily populated; it
1141 * should not be freed.
1142 */
1143static struct ref_cache *get_ref_cache(const char *submodule)
1144{
1145        struct ref_cache *refs;
1146
1147        if (!submodule || !*submodule)
1148                return &ref_cache;
1149
1150        for (refs = submodule_ref_caches; refs; refs = refs->next)
1151                if (!strcmp(submodule, refs->name))
1152                        return refs;
1153
1154        refs = create_ref_cache(submodule);
1155        refs->next = submodule_ref_caches;
1156        submodule_ref_caches = refs;
1157        return refs;
1158}
1159
1160/* The length of a peeled reference line in packed-refs, including EOL: */
1161#define PEELED_LINE_LENGTH 42
1162
1163/*
1164 * The packed-refs header line that we write out.  Perhaps other
1165 * traits will be added later.  The trailing space is required.
1166 */
1167static const char PACKED_REFS_HEADER[] =
1168        "# pack-refs with: peeled fully-peeled \n";
1169
1170/*
1171 * Parse one line from a packed-refs file.  Write the SHA1 to sha1.
1172 * Return a pointer to the refname within the line (null-terminated),
1173 * or NULL if there was a problem.
1174 */
1175static const char *parse_ref_line(char *line, unsigned char *sha1)
1176{
1177        /*
1178         * 42: the answer to everything.
1179         *
1180         * In this case, it happens to be the answer to
1181         *  40 (length of sha1 hex representation)
1182         *  +1 (space in between hex and name)
1183         *  +1 (newline at the end of the line)
1184         */
1185        int len = strlen(line) - 42;
1186
1187        if (len <= 0)
1188                return NULL;
1189        if (get_sha1_hex(line, sha1) < 0)
1190                return NULL;
1191        if (!isspace(line[40]))
1192                return NULL;
1193        line += 41;
1194        if (isspace(*line))
1195                return NULL;
1196        if (line[len] != '\n')
1197                return NULL;
1198        line[len] = 0;
1199
1200        return line;
1201}
1202
1203/*
1204 * Read f, which is a packed-refs file, into dir.
1205 *
1206 * A comment line of the form "# pack-refs with: " may contain zero or
1207 * more traits. We interpret the traits as follows:
1208 *
1209 *   No traits:
1210 *
1211 *      Probably no references are peeled. But if the file contains a
1212 *      peeled value for a reference, we will use it.
1213 *
1214 *   peeled:
1215 *
1216 *      References under "refs/tags/", if they *can* be peeled, *are*
1217 *      peeled in this file. References outside of "refs/tags/" are
1218 *      probably not peeled even if they could have been, but if we find
1219 *      a peeled value for such a reference we will use it.
1220 *
1221 *   fully-peeled:
1222 *
1223 *      All references in the file that can be peeled are peeled.
1224 *      Inversely (and this is more important), any references in the
1225 *      file for which no peeled value is recorded is not peelable. This
1226 *      trait should typically be written alongside "peeled" for
1227 *      compatibility with older clients, but we do not require it
1228 *      (i.e., "peeled" is a no-op if "fully-peeled" is set).
1229 */
1230static void read_packed_refs(FILE *f, struct ref_dir *dir)
1231{
1232        struct ref_entry *last = NULL;
1233        char refline[PATH_MAX];
1234        enum { PEELED_NONE, PEELED_TAGS, PEELED_FULLY } peeled = PEELED_NONE;
1235
1236        while (fgets(refline, sizeof(refline), f)) {
1237                unsigned char sha1[20];
1238                const char *refname;
1239                static const char header[] = "# pack-refs with:";
1240
1241                if (!strncmp(refline, header, sizeof(header)-1)) {
1242                        const char *traits = refline + sizeof(header) - 1;
1243                        if (strstr(traits, " fully-peeled "))
1244                                peeled = PEELED_FULLY;
1245                        else if (strstr(traits, " peeled "))
1246                                peeled = PEELED_TAGS;
1247                        /* perhaps other traits later as well */
1248                        continue;
1249                }
1250
1251                refname = parse_ref_line(refline, sha1);
1252                if (refname) {
1253                        last = create_ref_entry(refname, sha1, REF_ISPACKED, 1);
1254                        if (peeled == PEELED_FULLY ||
1255                            (peeled == PEELED_TAGS && starts_with(refname, "refs/tags/")))
1256                                last->flag |= REF_KNOWS_PEELED;
1257                        add_ref(dir, last);
1258                        continue;
1259                }
1260                if (last &&
1261                    refline[0] == '^' &&
1262                    strlen(refline) == PEELED_LINE_LENGTH &&
1263                    refline[PEELED_LINE_LENGTH - 1] == '\n' &&
1264                    !get_sha1_hex(refline + 1, sha1)) {
1265                        hashcpy(last->u.value.peeled, sha1);
1266                        /*
1267                         * Regardless of what the file header said,
1268                         * we definitely know the value of *this*
1269                         * reference:
1270                         */
1271                        last->flag |= REF_KNOWS_PEELED;
1272                }
1273        }
1274}
1275
1276/*
1277 * Get the packed_ref_cache for the specified ref_cache, creating it
1278 * if necessary.
1279 */
1280static struct packed_ref_cache *get_packed_ref_cache(struct ref_cache *refs)
1281{
1282        const char *packed_refs_file;
1283
1284        if (*refs->name)
1285                packed_refs_file = git_path_submodule(refs->name, "packed-refs");
1286        else
1287                packed_refs_file = git_path("packed-refs");
1288
1289        if (refs->packed &&
1290            !stat_validity_check(&refs->packed->validity, packed_refs_file))
1291                clear_packed_ref_cache(refs);
1292
1293        if (!refs->packed) {
1294                FILE *f;
1295
1296                refs->packed = xcalloc(1, sizeof(*refs->packed));
1297                acquire_packed_ref_cache(refs->packed);
1298                refs->packed->root = create_dir_entry(refs, "", 0, 0);
1299                f = fopen(packed_refs_file, "r");
1300                if (f) {
1301                        stat_validity_update(&refs->packed->validity, fileno(f));
1302                        read_packed_refs(f, get_ref_dir(refs->packed->root));
1303                        fclose(f);
1304                }
1305        }
1306        return refs->packed;
1307}
1308
1309static struct ref_dir *get_packed_ref_dir(struct packed_ref_cache *packed_ref_cache)
1310{
1311        return get_ref_dir(packed_ref_cache->root);
1312}
1313
1314static struct ref_dir *get_packed_refs(struct ref_cache *refs)
1315{
1316        return get_packed_ref_dir(get_packed_ref_cache(refs));
1317}
1318
1319void add_packed_ref(const char *refname, const unsigned char *sha1)
1320{
1321        struct packed_ref_cache *packed_ref_cache =
1322                get_packed_ref_cache(&ref_cache);
1323
1324        if (!packed_ref_cache->lock)
1325                die("internal error: packed refs not locked");
1326        add_ref(get_packed_ref_dir(packed_ref_cache),
1327                create_ref_entry(refname, sha1, REF_ISPACKED, 1));
1328}
1329
1330/*
1331 * Read the loose references from the namespace dirname into dir
1332 * (without recursing).  dirname must end with '/'.  dir must be the
1333 * directory entry corresponding to dirname.
1334 */
1335static void read_loose_refs(const char *dirname, struct ref_dir *dir)
1336{
1337        struct ref_cache *refs = dir->ref_cache;
1338        DIR *d;
1339        const char *path;
1340        struct dirent *de;
1341        int dirnamelen = strlen(dirname);
1342        struct strbuf refname;
1343
1344        if (*refs->name)
1345                path = git_path_submodule(refs->name, "%s", dirname);
1346        else
1347                path = git_path("%s", dirname);
1348
1349        d = opendir(path);
1350        if (!d)
1351                return;
1352
1353        strbuf_init(&refname, dirnamelen + 257);
1354        strbuf_add(&refname, dirname, dirnamelen);
1355
1356        while ((de = readdir(d)) != NULL) {
1357                unsigned char sha1[20];
1358                struct stat st;
1359                int flag;
1360                const char *refdir;
1361
1362                if (de->d_name[0] == '.')
1363                        continue;
1364                if (ends_with(de->d_name, ".lock"))
1365                        continue;
1366                strbuf_addstr(&refname, de->d_name);
1367                refdir = *refs->name
1368                        ? git_path_submodule(refs->name, "%s", refname.buf)
1369                        : git_path("%s", refname.buf);
1370                if (stat(refdir, &st) < 0) {
1371                        ; /* silently ignore */
1372                } else if (S_ISDIR(st.st_mode)) {
1373                        strbuf_addch(&refname, '/');
1374                        add_entry_to_dir(dir,
1375                                         create_dir_entry(refs, refname.buf,
1376                                                          refname.len, 1));
1377                } else {
1378                        if (*refs->name) {
1379                                hashclr(sha1);
1380                                flag = 0;
1381                                if (resolve_gitlink_ref(refs->name, refname.buf, sha1) < 0) {
1382                                        hashclr(sha1);
1383                                        flag |= REF_ISBROKEN;
1384                                }
1385                        } else if (read_ref_full(refname.buf, sha1, 1, &flag)) {
1386                                hashclr(sha1);
1387                                flag |= REF_ISBROKEN;
1388                        }
1389                        add_entry_to_dir(dir,
1390                                         create_ref_entry(refname.buf, sha1, flag, 1));
1391                }
1392                strbuf_setlen(&refname, dirnamelen);
1393        }
1394        strbuf_release(&refname);
1395        closedir(d);
1396}
1397
1398static struct ref_dir *get_loose_refs(struct ref_cache *refs)
1399{
1400        if (!refs->loose) {
1401                /*
1402                 * Mark the top-level directory complete because we
1403                 * are about to read the only subdirectory that can
1404                 * hold references:
1405                 */
1406                refs->loose = create_dir_entry(refs, "", 0, 0);
1407                /*
1408                 * Create an incomplete entry for "refs/":
1409                 */
1410                add_entry_to_dir(get_ref_dir(refs->loose),
1411                                 create_dir_entry(refs, "refs/", 5, 1));
1412        }
1413        return get_ref_dir(refs->loose);
1414}
1415
1416/* We allow "recursive" symbolic refs. Only within reason, though */
1417#define MAXDEPTH 5
1418#define MAXREFLEN (1024)
1419
1420/*
1421 * Called by resolve_gitlink_ref_recursive() after it failed to read
1422 * from the loose refs in ref_cache refs. Find <refname> in the
1423 * packed-refs file for the submodule.
1424 */
1425static int resolve_gitlink_packed_ref(struct ref_cache *refs,
1426                                      const char *refname, unsigned char *sha1)
1427{
1428        struct ref_entry *ref;
1429        struct ref_dir *dir = get_packed_refs(refs);
1430
1431        ref = find_ref(dir, refname);
1432        if (ref == NULL)
1433                return -1;
1434
1435        hashcpy(sha1, ref->u.value.sha1);
1436        return 0;
1437}
1438
1439static int resolve_gitlink_ref_recursive(struct ref_cache *refs,
1440                                         const char *refname, unsigned char *sha1,
1441                                         int recursion)
1442{
1443        int fd, len;
1444        char buffer[128], *p;
1445        char *path;
1446
1447        if (recursion > MAXDEPTH || strlen(refname) > MAXREFLEN)
1448                return -1;
1449        path = *refs->name
1450                ? git_path_submodule(refs->name, "%s", refname)
1451                : git_path("%s", refname);
1452        fd = open(path, O_RDONLY);
1453        if (fd < 0)
1454                return resolve_gitlink_packed_ref(refs, refname, sha1);
1455
1456        len = read(fd, buffer, sizeof(buffer)-1);
1457        close(fd);
1458        if (len < 0)
1459                return -1;
1460        while (len && isspace(buffer[len-1]))
1461                len--;
1462        buffer[len] = 0;
1463
1464        /* Was it a detached head or an old-fashioned symlink? */
1465        if (!get_sha1_hex(buffer, sha1))
1466                return 0;
1467
1468        /* Symref? */
1469        if (strncmp(buffer, "ref:", 4))
1470                return -1;
1471        p = buffer + 4;
1472        while (isspace(*p))
1473                p++;
1474
1475        return resolve_gitlink_ref_recursive(refs, p, sha1, recursion+1);
1476}
1477
1478int resolve_gitlink_ref(const char *path, const char *refname, unsigned char *sha1)
1479{
1480        int len = strlen(path), retval;
1481        char *submodule;
1482        struct ref_cache *refs;
1483
1484        while (len && path[len-1] == '/')
1485                len--;
1486        if (!len)
1487                return -1;
1488        submodule = xstrndup(path, len);
1489        refs = get_ref_cache(submodule);
1490        free(submodule);
1491
1492        retval = resolve_gitlink_ref_recursive(refs, refname, sha1, 0);
1493        return retval;
1494}
1495
1496/*
1497 * Return the ref_entry for the given refname from the packed
1498 * references.  If it does not exist, return NULL.
1499 */
1500static struct ref_entry *get_packed_ref(const char *refname)
1501{
1502        return find_ref(get_packed_refs(&ref_cache), refname);
1503}
1504
1505/*
1506 * A loose ref file doesn't exist; check for a packed ref.  The
1507 * options are forwarded from resolve_safe_unsafe().
1508 */
1509static const char *handle_missing_loose_ref(const char *refname,
1510                                            unsigned char *sha1,
1511                                            int reading,
1512                                            int *flag)
1513{
1514        struct ref_entry *entry;
1515
1516        /*
1517         * The loose reference file does not exist; check for a packed
1518         * reference.
1519         */
1520        entry = get_packed_ref(refname);
1521        if (entry) {
1522                hashcpy(sha1, entry->u.value.sha1);
1523                if (flag)
1524                        *flag |= REF_ISPACKED;
1525                return refname;
1526        }
1527        /* The reference is not a packed reference, either. */
1528        if (reading) {
1529                return NULL;
1530        } else {
1531                hashclr(sha1);
1532                return refname;
1533        }
1534}
1535
1536const char *resolve_ref_unsafe(const char *refname, unsigned char *sha1, int reading, int *flag)
1537{
1538        int depth = MAXDEPTH;
1539        ssize_t len;
1540        char buffer[256];
1541        static char refname_buffer[256];
1542
1543        if (flag)
1544                *flag = 0;
1545
1546        if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL))
1547                return NULL;
1548
1549        for (;;) {
1550                char path[PATH_MAX];
1551                struct stat st;
1552                char *buf;
1553                int fd;
1554
1555                if (--depth < 0)
1556                        return NULL;
1557
1558                git_snpath(path, sizeof(path), "%s", refname);
1559
1560                /*
1561                 * We might have to loop back here to avoid a race
1562                 * condition: first we lstat() the file, then we try
1563                 * to read it as a link or as a file.  But if somebody
1564                 * changes the type of the file (file <-> directory
1565                 * <-> symlink) between the lstat() and reading, then
1566                 * we don't want to report that as an error but rather
1567                 * try again starting with the lstat().
1568                 */
1569        stat_ref:
1570                if (lstat(path, &st) < 0) {
1571                        if (errno == ENOENT)
1572                                return handle_missing_loose_ref(refname, sha1,
1573                                                                reading, flag);
1574                        else
1575                                return NULL;
1576                }
1577
1578                /* Follow "normalized" - ie "refs/.." symlinks by hand */
1579                if (S_ISLNK(st.st_mode)) {
1580                        len = readlink(path, buffer, sizeof(buffer)-1);
1581                        if (len < 0) {
1582                                if (errno == ENOENT || errno == EINVAL)
1583                                        /* inconsistent with lstat; retry */
1584                                        goto stat_ref;
1585                                else
1586                                        return NULL;
1587                        }
1588                        buffer[len] = 0;
1589                        if (starts_with(buffer, "refs/") &&
1590                                        !check_refname_format(buffer, 0)) {
1591                                strcpy(refname_buffer, buffer);
1592                                refname = refname_buffer;
1593                                if (flag)
1594                                        *flag |= REF_ISSYMREF;
1595                                continue;
1596                        }
1597                }
1598
1599                /* Is it a directory? */
1600                if (S_ISDIR(st.st_mode)) {
1601                        errno = EISDIR;
1602                        return NULL;
1603                }
1604
1605                /*
1606                 * Anything else, just open it and try to use it as
1607                 * a ref
1608                 */
1609                fd = open(path, O_RDONLY);
1610                if (fd < 0) {
1611                        if (errno == ENOENT)
1612                                /* inconsistent with lstat; retry */
1613                                goto stat_ref;
1614                        else
1615                                return NULL;
1616                }
1617                len = read_in_full(fd, buffer, sizeof(buffer)-1);
1618                close(fd);
1619                if (len < 0)
1620                        return NULL;
1621                while (len && isspace(buffer[len-1]))
1622                        len--;
1623                buffer[len] = '\0';
1624
1625                /*
1626                 * Is it a symbolic ref?
1627                 */
1628                if (!starts_with(buffer, "ref:")) {
1629                        /*
1630                         * Please note that FETCH_HEAD has a second
1631                         * line containing other data.
1632                         */
1633                        if (get_sha1_hex(buffer, sha1) ||
1634                            (buffer[40] != '\0' && !isspace(buffer[40]))) {
1635                                if (flag)
1636                                        *flag |= REF_ISBROKEN;
1637                                return NULL;
1638                        }
1639                        return refname;
1640                }
1641                if (flag)
1642                        *flag |= REF_ISSYMREF;
1643                buf = buffer + 4;
1644                while (isspace(*buf))
1645                        buf++;
1646                if (check_refname_format(buf, REFNAME_ALLOW_ONELEVEL)) {
1647                        if (flag)
1648                                *flag |= REF_ISBROKEN;
1649                        return NULL;
1650                }
1651                refname = strcpy(refname_buffer, buf);
1652        }
1653}
1654
1655char *resolve_refdup(const char *ref, unsigned char *sha1, int reading, int *flag)
1656{
1657        const char *ret = resolve_ref_unsafe(ref, sha1, reading, flag);
1658        return ret ? xstrdup(ret) : NULL;
1659}
1660
1661/* The argument to filter_refs */
1662struct ref_filter {
1663        const char *pattern;
1664        each_ref_fn *fn;
1665        void *cb_data;
1666};
1667
1668int read_ref_full(const char *refname, unsigned char *sha1, int reading, int *flags)
1669{
1670        if (resolve_ref_unsafe(refname, sha1, reading, flags))
1671                return 0;
1672        return -1;
1673}
1674
1675int read_ref(const char *refname, unsigned char *sha1)
1676{
1677        return read_ref_full(refname, sha1, 1, NULL);
1678}
1679
1680int ref_exists(const char *refname)
1681{
1682        unsigned char sha1[20];
1683        return !!resolve_ref_unsafe(refname, sha1, 1, NULL);
1684}
1685
1686static int filter_refs(const char *refname, const unsigned char *sha1, int flags,
1687                       void *data)
1688{
1689        struct ref_filter *filter = (struct ref_filter *)data;
1690        if (wildmatch(filter->pattern, refname, 0, NULL))
1691                return 0;
1692        return filter->fn(refname, sha1, flags, filter->cb_data);
1693}
1694
1695enum peel_status {
1696        /* object was peeled successfully: */
1697        PEEL_PEELED = 0,
1698
1699        /*
1700         * object cannot be peeled because the named object (or an
1701         * object referred to by a tag in the peel chain), does not
1702         * exist.
1703         */
1704        PEEL_INVALID = -1,
1705
1706        /* object cannot be peeled because it is not a tag: */
1707        PEEL_NON_TAG = -2,
1708
1709        /* ref_entry contains no peeled value because it is a symref: */
1710        PEEL_IS_SYMREF = -3,
1711
1712        /*
1713         * ref_entry cannot be peeled because it is broken (i.e., the
1714         * symbolic reference cannot even be resolved to an object
1715         * name):
1716         */
1717        PEEL_BROKEN = -4
1718};
1719
1720/*
1721 * Peel the named object; i.e., if the object is a tag, resolve the
1722 * tag recursively until a non-tag is found.  If successful, store the
1723 * result to sha1 and return PEEL_PEELED.  If the object is not a tag
1724 * or is not valid, return PEEL_NON_TAG or PEEL_INVALID, respectively,
1725 * and leave sha1 unchanged.
1726 */
1727static enum peel_status peel_object(const unsigned char *name, unsigned char *sha1)
1728{
1729        struct object *o = lookup_unknown_object(name);
1730
1731        if (o->type == OBJ_NONE) {
1732                int type = sha1_object_info(name, NULL);
1733                if (type < 0)
1734                        return PEEL_INVALID;
1735                o->type = type;
1736        }
1737
1738        if (o->type != OBJ_TAG)
1739                return PEEL_NON_TAG;
1740
1741        o = deref_tag_noverify(o);
1742        if (!o)
1743                return PEEL_INVALID;
1744
1745        hashcpy(sha1, o->sha1);
1746        return PEEL_PEELED;
1747}
1748
1749/*
1750 * Peel the entry (if possible) and return its new peel_status.  If
1751 * repeel is true, re-peel the entry even if there is an old peeled
1752 * value that is already stored in it.
1753 *
1754 * It is OK to call this function with a packed reference entry that
1755 * might be stale and might even refer to an object that has since
1756 * been garbage-collected.  In such a case, if the entry has
1757 * REF_KNOWS_PEELED then leave the status unchanged and return
1758 * PEEL_PEELED or PEEL_NON_TAG; otherwise, return PEEL_INVALID.
1759 */
1760static enum peel_status peel_entry(struct ref_entry *entry, int repeel)
1761{
1762        enum peel_status status;
1763
1764        if (entry->flag & REF_KNOWS_PEELED) {
1765                if (repeel) {
1766                        entry->flag &= ~REF_KNOWS_PEELED;
1767                        hashclr(entry->u.value.peeled);
1768                } else {
1769                        return is_null_sha1(entry->u.value.peeled) ?
1770                                PEEL_NON_TAG : PEEL_PEELED;
1771                }
1772        }
1773        if (entry->flag & REF_ISBROKEN)
1774                return PEEL_BROKEN;
1775        if (entry->flag & REF_ISSYMREF)
1776                return PEEL_IS_SYMREF;
1777
1778        status = peel_object(entry->u.value.sha1, entry->u.value.peeled);
1779        if (status == PEEL_PEELED || status == PEEL_NON_TAG)
1780                entry->flag |= REF_KNOWS_PEELED;
1781        return status;
1782}
1783
1784int peel_ref(const char *refname, unsigned char *sha1)
1785{
1786        int flag;
1787        unsigned char base[20];
1788
1789        if (current_ref && (current_ref->name == refname
1790                            || !strcmp(current_ref->name, refname))) {
1791                if (peel_entry(current_ref, 0))
1792                        return -1;
1793                hashcpy(sha1, current_ref->u.value.peeled);
1794                return 0;
1795        }
1796
1797        if (read_ref_full(refname, base, 1, &flag))
1798                return -1;
1799
1800        /*
1801         * If the reference is packed, read its ref_entry from the
1802         * cache in the hope that we already know its peeled value.
1803         * We only try this optimization on packed references because
1804         * (a) forcing the filling of the loose reference cache could
1805         * be expensive and (b) loose references anyway usually do not
1806         * have REF_KNOWS_PEELED.
1807         */
1808        if (flag & REF_ISPACKED) {
1809                struct ref_entry *r = get_packed_ref(refname);
1810                if (r) {
1811                        if (peel_entry(r, 0))
1812                                return -1;
1813                        hashcpy(sha1, r->u.value.peeled);
1814                        return 0;
1815                }
1816        }
1817
1818        return peel_object(base, sha1);
1819}
1820
1821struct warn_if_dangling_data {
1822        FILE *fp;
1823        const char *refname;
1824        const struct string_list *refnames;
1825        const char *msg_fmt;
1826};
1827
1828static int warn_if_dangling_symref(const char *refname, const unsigned char *sha1,
1829                                   int flags, void *cb_data)
1830{
1831        struct warn_if_dangling_data *d = cb_data;
1832        const char *resolves_to;
1833        unsigned char junk[20];
1834
1835        if (!(flags & REF_ISSYMREF))
1836                return 0;
1837
1838        resolves_to = resolve_ref_unsafe(refname, junk, 0, NULL);
1839        if (!resolves_to
1840            || (d->refname
1841                ? strcmp(resolves_to, d->refname)
1842                : !string_list_has_string(d->refnames, resolves_to))) {
1843                return 0;
1844        }
1845
1846        fprintf(d->fp, d->msg_fmt, refname);
1847        fputc('\n', d->fp);
1848        return 0;
1849}
1850
1851void warn_dangling_symref(FILE *fp, const char *msg_fmt, const char *refname)
1852{
1853        struct warn_if_dangling_data data;
1854
1855        data.fp = fp;
1856        data.refname = refname;
1857        data.refnames = NULL;
1858        data.msg_fmt = msg_fmt;
1859        for_each_rawref(warn_if_dangling_symref, &data);
1860}
1861
1862void warn_dangling_symrefs(FILE *fp, const char *msg_fmt, const struct string_list *refnames)
1863{
1864        struct warn_if_dangling_data data;
1865
1866        data.fp = fp;
1867        data.refname = NULL;
1868        data.refnames = refnames;
1869        data.msg_fmt = msg_fmt;
1870        for_each_rawref(warn_if_dangling_symref, &data);
1871}
1872
1873/*
1874 * Call fn for each reference in the specified ref_cache, omitting
1875 * references not in the containing_dir of base.  fn is called for all
1876 * references, including broken ones.  If fn ever returns a non-zero
1877 * value, stop the iteration and return that value; otherwise, return
1878 * 0.
1879 */
1880static int do_for_each_entry(struct ref_cache *refs, const char *base,
1881                             each_ref_entry_fn fn, void *cb_data)
1882{
1883        struct packed_ref_cache *packed_ref_cache;
1884        struct ref_dir *loose_dir;
1885        struct ref_dir *packed_dir;
1886        int retval = 0;
1887
1888        /*
1889         * We must make sure that all loose refs are read before accessing the
1890         * packed-refs file; this avoids a race condition in which loose refs
1891         * are migrated to the packed-refs file by a simultaneous process, but
1892         * our in-memory view is from before the migration. get_packed_ref_cache()
1893         * takes care of making sure our view is up to date with what is on
1894         * disk.
1895         */
1896        loose_dir = get_loose_refs(refs);
1897        if (base && *base) {
1898                loose_dir = find_containing_dir(loose_dir, base, 0);
1899        }
1900        if (loose_dir)
1901                prime_ref_dir(loose_dir);
1902
1903        packed_ref_cache = get_packed_ref_cache(refs);
1904        acquire_packed_ref_cache(packed_ref_cache);
1905        packed_dir = get_packed_ref_dir(packed_ref_cache);
1906        if (base && *base) {
1907                packed_dir = find_containing_dir(packed_dir, base, 0);
1908        }
1909
1910        if (packed_dir && loose_dir) {
1911                sort_ref_dir(packed_dir);
1912                sort_ref_dir(loose_dir);
1913                retval = do_for_each_entry_in_dirs(
1914                                packed_dir, loose_dir, fn, cb_data);
1915        } else if (packed_dir) {
1916                sort_ref_dir(packed_dir);
1917                retval = do_for_each_entry_in_dir(
1918                                packed_dir, 0, fn, cb_data);
1919        } else if (loose_dir) {
1920                sort_ref_dir(loose_dir);
1921                retval = do_for_each_entry_in_dir(
1922                                loose_dir, 0, fn, cb_data);
1923        }
1924
1925        release_packed_ref_cache(packed_ref_cache);
1926        return retval;
1927}
1928
1929/*
1930 * Call fn for each reference in the specified ref_cache for which the
1931 * refname begins with base.  If trim is non-zero, then trim that many
1932 * characters off the beginning of each refname before passing the
1933 * refname to fn.  flags can be DO_FOR_EACH_INCLUDE_BROKEN to include
1934 * broken references in the iteration.  If fn ever returns a non-zero
1935 * value, stop the iteration and return that value; otherwise, return
1936 * 0.
1937 */
1938static int do_for_each_ref(struct ref_cache *refs, const char *base,
1939                           each_ref_fn fn, int trim, int flags, void *cb_data)
1940{
1941        struct ref_entry_cb data;
1942        data.base = base;
1943        data.trim = trim;
1944        data.flags = flags;
1945        data.fn = fn;
1946        data.cb_data = cb_data;
1947
1948        return do_for_each_entry(refs, base, do_one_ref, &data);
1949}
1950
1951static int do_head_ref(const char *submodule, each_ref_fn fn, void *cb_data)
1952{
1953        unsigned char sha1[20];
1954        int flag;
1955
1956        if (submodule) {
1957                if (resolve_gitlink_ref(submodule, "HEAD", sha1) == 0)
1958                        return fn("HEAD", sha1, 0, cb_data);
1959
1960                return 0;
1961        }
1962
1963        if (!read_ref_full("HEAD", sha1, 1, &flag))
1964                return fn("HEAD", sha1, flag, cb_data);
1965
1966        return 0;
1967}
1968
1969int head_ref(each_ref_fn fn, void *cb_data)
1970{
1971        return do_head_ref(NULL, fn, cb_data);
1972}
1973
1974int head_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
1975{
1976        return do_head_ref(submodule, fn, cb_data);
1977}
1978
1979int for_each_ref(each_ref_fn fn, void *cb_data)
1980{
1981        return do_for_each_ref(&ref_cache, "", fn, 0, 0, cb_data);
1982}
1983
1984int for_each_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
1985{
1986        return do_for_each_ref(get_ref_cache(submodule), "", fn, 0, 0, cb_data);
1987}
1988
1989int for_each_ref_in(const char *prefix, each_ref_fn fn, void *cb_data)
1990{
1991        return do_for_each_ref(&ref_cache, prefix, fn, strlen(prefix), 0, cb_data);
1992}
1993
1994int for_each_ref_in_submodule(const char *submodule, const char *prefix,
1995                each_ref_fn fn, void *cb_data)
1996{
1997        return do_for_each_ref(get_ref_cache(submodule), prefix, fn, strlen(prefix), 0, cb_data);
1998}
1999
2000int for_each_tag_ref(each_ref_fn fn, void *cb_data)
2001{
2002        return for_each_ref_in("refs/tags/", fn, cb_data);
2003}
2004
2005int for_each_tag_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
2006{
2007        return for_each_ref_in_submodule(submodule, "refs/tags/", fn, cb_data);
2008}
2009
2010int for_each_branch_ref(each_ref_fn fn, void *cb_data)
2011{
2012        return for_each_ref_in("refs/heads/", fn, cb_data);
2013}
2014
2015int for_each_branch_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
2016{
2017        return for_each_ref_in_submodule(submodule, "refs/heads/", fn, cb_data);
2018}
2019
2020int for_each_remote_ref(each_ref_fn fn, void *cb_data)
2021{
2022        return for_each_ref_in("refs/remotes/", fn, cb_data);
2023}
2024
2025int for_each_remote_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
2026{
2027        return for_each_ref_in_submodule(submodule, "refs/remotes/", fn, cb_data);
2028}
2029
2030int for_each_replace_ref(each_ref_fn fn, void *cb_data)
2031{
2032        return do_for_each_ref(&ref_cache, "refs/replace/", fn, 13, 0, cb_data);
2033}
2034
2035int head_ref_namespaced(each_ref_fn fn, void *cb_data)
2036{
2037        struct strbuf buf = STRBUF_INIT;
2038        int ret = 0;
2039        unsigned char sha1[20];
2040        int flag;
2041
2042        strbuf_addf(&buf, "%sHEAD", get_git_namespace());
2043        if (!read_ref_full(buf.buf, sha1, 1, &flag))
2044                ret = fn(buf.buf, sha1, flag, cb_data);
2045        strbuf_release(&buf);
2046
2047        return ret;
2048}
2049
2050int for_each_namespaced_ref(each_ref_fn fn, void *cb_data)
2051{
2052        struct strbuf buf = STRBUF_INIT;
2053        int ret;
2054        strbuf_addf(&buf, "%srefs/", get_git_namespace());
2055        ret = do_for_each_ref(&ref_cache, buf.buf, fn, 0, 0, cb_data);
2056        strbuf_release(&buf);
2057        return ret;
2058}
2059
2060int for_each_glob_ref_in(each_ref_fn fn, const char *pattern,
2061        const char *prefix, void *cb_data)
2062{
2063        struct strbuf real_pattern = STRBUF_INIT;
2064        struct ref_filter filter;
2065        int ret;
2066
2067        if (!prefix && !starts_with(pattern, "refs/"))
2068                strbuf_addstr(&real_pattern, "refs/");
2069        else if (prefix)
2070                strbuf_addstr(&real_pattern, prefix);
2071        strbuf_addstr(&real_pattern, pattern);
2072
2073        if (!has_glob_specials(pattern)) {
2074                /* Append implied '/' '*' if not present. */
2075                if (real_pattern.buf[real_pattern.len - 1] != '/')
2076                        strbuf_addch(&real_pattern, '/');
2077                /* No need to check for '*', there is none. */
2078                strbuf_addch(&real_pattern, '*');
2079        }
2080
2081        filter.pattern = real_pattern.buf;
2082        filter.fn = fn;
2083        filter.cb_data = cb_data;
2084        ret = for_each_ref(filter_refs, &filter);
2085
2086        strbuf_release(&real_pattern);
2087        return ret;
2088}
2089
2090int for_each_glob_ref(each_ref_fn fn, const char *pattern, void *cb_data)
2091{
2092        return for_each_glob_ref_in(fn, pattern, NULL, cb_data);
2093}
2094
2095int for_each_rawref(each_ref_fn fn, void *cb_data)
2096{
2097        return do_for_each_ref(&ref_cache, "", fn, 0,
2098                               DO_FOR_EACH_INCLUDE_BROKEN, cb_data);
2099}
2100
2101const char *prettify_refname(const char *name)
2102{
2103        return name + (
2104                starts_with(name, "refs/heads/") ? 11 :
2105                starts_with(name, "refs/tags/") ? 10 :
2106                starts_with(name, "refs/remotes/") ? 13 :
2107                0);
2108}
2109
2110static const char *ref_rev_parse_rules[] = {
2111        "%.*s",
2112        "refs/%.*s",
2113        "refs/tags/%.*s",
2114        "refs/heads/%.*s",
2115        "refs/remotes/%.*s",
2116        "refs/remotes/%.*s/HEAD",
2117        NULL
2118};
2119
2120int refname_match(const char *abbrev_name, const char *full_name)
2121{
2122        const char **p;
2123        const int abbrev_name_len = strlen(abbrev_name);
2124
2125        for (p = ref_rev_parse_rules; *p; p++) {
2126                if (!strcmp(full_name, mkpath(*p, abbrev_name_len, abbrev_name))) {
2127                        return 1;
2128                }
2129        }
2130
2131        return 0;
2132}
2133
2134static struct ref_lock *verify_lock(struct ref_lock *lock,
2135        const unsigned char *old_sha1, int mustexist)
2136{
2137        if (read_ref_full(lock->ref_name, lock->old_sha1, mustexist, NULL)) {
2138                error("Can't verify ref %s", lock->ref_name);
2139                unlock_ref(lock);
2140                return NULL;
2141        }
2142        if (hashcmp(lock->old_sha1, old_sha1)) {
2143                error("Ref %s is at %s but expected %s", lock->ref_name,
2144                        sha1_to_hex(lock->old_sha1), sha1_to_hex(old_sha1));
2145                unlock_ref(lock);
2146                return NULL;
2147        }
2148        return lock;
2149}
2150
2151static int remove_empty_directories(const char *file)
2152{
2153        /* we want to create a file but there is a directory there;
2154         * if that is an empty directory (or a directory that contains
2155         * only empty directories), remove them.
2156         */
2157        struct strbuf path;
2158        int result;
2159
2160        strbuf_init(&path, 20);
2161        strbuf_addstr(&path, file);
2162
2163        result = remove_dir_recursively(&path, REMOVE_DIR_EMPTY_ONLY);
2164
2165        strbuf_release(&path);
2166
2167        return result;
2168}
2169
2170/*
2171 * *string and *len will only be substituted, and *string returned (for
2172 * later free()ing) if the string passed in is a magic short-hand form
2173 * to name a branch.
2174 */
2175static char *substitute_branch_name(const char **string, int *len)
2176{
2177        struct strbuf buf = STRBUF_INIT;
2178        int ret = interpret_branch_name(*string, *len, &buf);
2179
2180        if (ret == *len) {
2181                size_t size;
2182                *string = strbuf_detach(&buf, &size);
2183                *len = size;
2184                return (char *)*string;
2185        }
2186
2187        return NULL;
2188}
2189
2190int dwim_ref(const char *str, int len, unsigned char *sha1, char **ref)
2191{
2192        char *last_branch = substitute_branch_name(&str, &len);
2193        const char **p, *r;
2194        int refs_found = 0;
2195
2196        *ref = NULL;
2197        for (p = ref_rev_parse_rules; *p; p++) {
2198                char fullref[PATH_MAX];
2199                unsigned char sha1_from_ref[20];
2200                unsigned char *this_result;
2201                int flag;
2202
2203                this_result = refs_found ? sha1_from_ref : sha1;
2204                mksnpath(fullref, sizeof(fullref), *p, len, str);
2205                r = resolve_ref_unsafe(fullref, this_result, 1, &flag);
2206                if (r) {
2207                        if (!refs_found++)
2208                                *ref = xstrdup(r);
2209                        if (!warn_ambiguous_refs)
2210                                break;
2211                } else if ((flag & REF_ISSYMREF) && strcmp(fullref, "HEAD")) {
2212                        warning("ignoring dangling symref %s.", fullref);
2213                } else if ((flag & REF_ISBROKEN) && strchr(fullref, '/')) {
2214                        warning("ignoring broken ref %s.", fullref);
2215                }
2216        }
2217        free(last_branch);
2218        return refs_found;
2219}
2220
2221int dwim_log(const char *str, int len, unsigned char *sha1, char **log)
2222{
2223        char *last_branch = substitute_branch_name(&str, &len);
2224        const char **p;
2225        int logs_found = 0;
2226
2227        *log = NULL;
2228        for (p = ref_rev_parse_rules; *p; p++) {
2229                unsigned char hash[20];
2230                char path[PATH_MAX];
2231                const char *ref, *it;
2232
2233                mksnpath(path, sizeof(path), *p, len, str);
2234                ref = resolve_ref_unsafe(path, hash, 1, NULL);
2235                if (!ref)
2236                        continue;
2237                if (reflog_exists(path))
2238                        it = path;
2239                else if (strcmp(ref, path) && reflog_exists(ref))
2240                        it = ref;
2241                else
2242                        continue;
2243                if (!logs_found++) {
2244                        *log = xstrdup(it);
2245                        hashcpy(sha1, hash);
2246                }
2247                if (!warn_ambiguous_refs)
2248                        break;
2249        }
2250        free(last_branch);
2251        return logs_found;
2252}
2253
2254static struct ref_lock *lock_ref_sha1_basic(const char *refname,
2255                                            const unsigned char *old_sha1,
2256                                            int flags, int *type_p)
2257{
2258        char *ref_file;
2259        const char *orig_refname = refname;
2260        struct ref_lock *lock;
2261        int last_errno = 0;
2262        int type, lflags;
2263        int mustexist = (old_sha1 && !is_null_sha1(old_sha1));
2264        int missing = 0;
2265        int attempts_remaining = 3;
2266
2267        lock = xcalloc(1, sizeof(struct ref_lock));
2268        lock->lock_fd = -1;
2269
2270        refname = resolve_ref_unsafe(refname, lock->old_sha1, mustexist, &type);
2271        if (!refname && errno == EISDIR) {
2272                /* we are trying to lock foo but we used to
2273                 * have foo/bar which now does not exist;
2274                 * it is normal for the empty directory 'foo'
2275                 * to remain.
2276                 */
2277                ref_file = git_path("%s", orig_refname);
2278                if (remove_empty_directories(ref_file)) {
2279                        last_errno = errno;
2280                        error("there are still refs under '%s'", orig_refname);
2281                        goto error_return;
2282                }
2283                refname = resolve_ref_unsafe(orig_refname, lock->old_sha1, mustexist, &type);
2284        }
2285        if (type_p)
2286            *type_p = type;
2287        if (!refname) {
2288                last_errno = errno;
2289                error("unable to resolve reference %s: %s",
2290                        orig_refname, strerror(errno));
2291                goto error_return;
2292        }
2293        missing = is_null_sha1(lock->old_sha1);
2294        /* When the ref did not exist and we are creating it,
2295         * make sure there is no existing ref that is packed
2296         * whose name begins with our refname, nor a ref whose
2297         * name is a proper prefix of our refname.
2298         */
2299        if (missing &&
2300             !is_refname_available(refname, NULL, get_packed_refs(&ref_cache))) {
2301                last_errno = ENOTDIR;
2302                goto error_return;
2303        }
2304
2305        lock->lk = xcalloc(1, sizeof(struct lock_file));
2306
2307        lflags = 0;
2308        if (flags & REF_NODEREF) {
2309                refname = orig_refname;
2310                lflags |= LOCK_NODEREF;
2311        }
2312        lock->ref_name = xstrdup(refname);
2313        lock->orig_ref_name = xstrdup(orig_refname);
2314        ref_file = git_path("%s", refname);
2315        if (missing)
2316                lock->force_write = 1;
2317        if ((flags & REF_NODEREF) && (type & REF_ISSYMREF))
2318                lock->force_write = 1;
2319
2320 retry:
2321        switch (safe_create_leading_directories(ref_file)) {
2322        case SCLD_OK:
2323                break; /* success */
2324        case SCLD_VANISHED:
2325                if (--attempts_remaining > 0)
2326                        goto retry;
2327                /* fall through */
2328        default:
2329                last_errno = errno;
2330                error("unable to create directory for %s", ref_file);
2331                goto error_return;
2332        }
2333
2334        lock->lock_fd = hold_lock_file_for_update(lock->lk, ref_file, lflags);
2335        if (lock->lock_fd < 0) {
2336                if (errno == ENOENT && --attempts_remaining > 0)
2337                        /*
2338                         * Maybe somebody just deleted one of the
2339                         * directories leading to ref_file.  Try
2340                         * again:
2341                         */
2342                        goto retry;
2343                else
2344                        unable_to_lock_index_die(ref_file, errno);
2345        }
2346        return old_sha1 ? verify_lock(lock, old_sha1, mustexist) : lock;
2347
2348 error_return:
2349        unlock_ref(lock);
2350        errno = last_errno;
2351        return NULL;
2352}
2353
2354struct ref_lock *lock_ref_sha1(const char *refname, const unsigned char *old_sha1)
2355{
2356        char refpath[PATH_MAX];
2357        if (check_refname_format(refname, 0))
2358                return NULL;
2359        strcpy(refpath, mkpath("refs/%s", refname));
2360        return lock_ref_sha1_basic(refpath, old_sha1, 0, NULL);
2361}
2362
2363struct ref_lock *lock_any_ref_for_update(const char *refname,
2364                                         const unsigned char *old_sha1,
2365                                         int flags, int *type_p)
2366{
2367        if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL))
2368                return NULL;
2369        return lock_ref_sha1_basic(refname, old_sha1, flags, type_p);
2370}
2371
2372/*
2373 * Write an entry to the packed-refs file for the specified refname.
2374 * If peeled is non-NULL, write it as the entry's peeled value.
2375 */
2376static void write_packed_entry(int fd, char *refname, unsigned char *sha1,
2377                               unsigned char *peeled)
2378{
2379        char line[PATH_MAX + 100];
2380        int len;
2381
2382        len = snprintf(line, sizeof(line), "%s %s\n",
2383                       sha1_to_hex(sha1), refname);
2384        /* this should not happen but just being defensive */
2385        if (len > sizeof(line))
2386                die("too long a refname '%s'", refname);
2387        write_or_die(fd, line, len);
2388
2389        if (peeled) {
2390                if (snprintf(line, sizeof(line), "^%s\n",
2391                             sha1_to_hex(peeled)) != PEELED_LINE_LENGTH)
2392                        die("internal error");
2393                write_or_die(fd, line, PEELED_LINE_LENGTH);
2394        }
2395}
2396
2397/*
2398 * An each_ref_entry_fn that writes the entry to a packed-refs file.
2399 */
2400static int write_packed_entry_fn(struct ref_entry *entry, void *cb_data)
2401{
2402        int *fd = cb_data;
2403        enum peel_status peel_status = peel_entry(entry, 0);
2404
2405        if (peel_status != PEEL_PEELED && peel_status != PEEL_NON_TAG)
2406                error("internal error: %s is not a valid packed reference!",
2407                      entry->name);
2408        write_packed_entry(*fd, entry->name, entry->u.value.sha1,
2409                           peel_status == PEEL_PEELED ?
2410                           entry->u.value.peeled : NULL);
2411        return 0;
2412}
2413
2414int lock_packed_refs(int flags)
2415{
2416        struct packed_ref_cache *packed_ref_cache;
2417
2418        if (hold_lock_file_for_update(&packlock, git_path("packed-refs"), flags) < 0)
2419                return -1;
2420        /*
2421         * Get the current packed-refs while holding the lock.  If the
2422         * packed-refs file has been modified since we last read it,
2423         * this will automatically invalidate the cache and re-read
2424         * the packed-refs file.
2425         */
2426        packed_ref_cache = get_packed_ref_cache(&ref_cache);
2427        packed_ref_cache->lock = &packlock;
2428        /* Increment the reference count to prevent it from being freed: */
2429        acquire_packed_ref_cache(packed_ref_cache);
2430        return 0;
2431}
2432
2433int commit_packed_refs(void)
2434{
2435        struct packed_ref_cache *packed_ref_cache =
2436                get_packed_ref_cache(&ref_cache);
2437        int error = 0;
2438
2439        if (!packed_ref_cache->lock)
2440                die("internal error: packed-refs not locked");
2441        write_or_die(packed_ref_cache->lock->fd,
2442                     PACKED_REFS_HEADER, strlen(PACKED_REFS_HEADER));
2443
2444        do_for_each_entry_in_dir(get_packed_ref_dir(packed_ref_cache),
2445                                 0, write_packed_entry_fn,
2446                                 &packed_ref_cache->lock->fd);
2447        if (commit_lock_file(packed_ref_cache->lock))
2448                error = -1;
2449        packed_ref_cache->lock = NULL;
2450        release_packed_ref_cache(packed_ref_cache);
2451        return error;
2452}
2453
2454void rollback_packed_refs(void)
2455{
2456        struct packed_ref_cache *packed_ref_cache =
2457                get_packed_ref_cache(&ref_cache);
2458
2459        if (!packed_ref_cache->lock)
2460                die("internal error: packed-refs not locked");
2461        rollback_lock_file(packed_ref_cache->lock);
2462        packed_ref_cache->lock = NULL;
2463        release_packed_ref_cache(packed_ref_cache);
2464        clear_packed_ref_cache(&ref_cache);
2465}
2466
2467struct ref_to_prune {
2468        struct ref_to_prune *next;
2469        unsigned char sha1[20];
2470        char name[FLEX_ARRAY];
2471};
2472
2473struct pack_refs_cb_data {
2474        unsigned int flags;
2475        struct ref_dir *packed_refs;
2476        struct ref_to_prune *ref_to_prune;
2477};
2478
2479/*
2480 * An each_ref_entry_fn that is run over loose references only.  If
2481 * the loose reference can be packed, add an entry in the packed ref
2482 * cache.  If the reference should be pruned, also add it to
2483 * ref_to_prune in the pack_refs_cb_data.
2484 */
2485static int pack_if_possible_fn(struct ref_entry *entry, void *cb_data)
2486{
2487        struct pack_refs_cb_data *cb = cb_data;
2488        enum peel_status peel_status;
2489        struct ref_entry *packed_entry;
2490        int is_tag_ref = starts_with(entry->name, "refs/tags/");
2491
2492        /* ALWAYS pack tags */
2493        if (!(cb->flags & PACK_REFS_ALL) && !is_tag_ref)
2494                return 0;
2495
2496        /* Do not pack symbolic or broken refs: */
2497        if ((entry->flag & REF_ISSYMREF) || !ref_resolves_to_object(entry))
2498                return 0;
2499
2500        /* Add a packed ref cache entry equivalent to the loose entry. */
2501        peel_status = peel_entry(entry, 1);
2502        if (peel_status != PEEL_PEELED && peel_status != PEEL_NON_TAG)
2503                die("internal error peeling reference %s (%s)",
2504                    entry->name, sha1_to_hex(entry->u.value.sha1));
2505        packed_entry = find_ref(cb->packed_refs, entry->name);
2506        if (packed_entry) {
2507                /* Overwrite existing packed entry with info from loose entry */
2508                packed_entry->flag = REF_ISPACKED | REF_KNOWS_PEELED;
2509                hashcpy(packed_entry->u.value.sha1, entry->u.value.sha1);
2510        } else {
2511                packed_entry = create_ref_entry(entry->name, entry->u.value.sha1,
2512                                                REF_ISPACKED | REF_KNOWS_PEELED, 0);
2513                add_ref(cb->packed_refs, packed_entry);
2514        }
2515        hashcpy(packed_entry->u.value.peeled, entry->u.value.peeled);
2516
2517        /* Schedule the loose reference for pruning if requested. */
2518        if ((cb->flags & PACK_REFS_PRUNE)) {
2519                int namelen = strlen(entry->name) + 1;
2520                struct ref_to_prune *n = xcalloc(1, sizeof(*n) + namelen);
2521                hashcpy(n->sha1, entry->u.value.sha1);
2522                strcpy(n->name, entry->name);
2523                n->next = cb->ref_to_prune;
2524                cb->ref_to_prune = n;
2525        }
2526        return 0;
2527}
2528
2529/*
2530 * Remove empty parents, but spare refs/ and immediate subdirs.
2531 * Note: munges *name.
2532 */
2533static void try_remove_empty_parents(char *name)
2534{
2535        char *p, *q;
2536        int i;
2537        p = name;
2538        for (i = 0; i < 2; i++) { /* refs/{heads,tags,...}/ */
2539                while (*p && *p != '/')
2540                        p++;
2541                /* tolerate duplicate slashes; see check_refname_format() */
2542                while (*p == '/')
2543                        p++;
2544        }
2545        for (q = p; *q; q++)
2546                ;
2547        while (1) {
2548                while (q > p && *q != '/')
2549                        q--;
2550                while (q > p && *(q-1) == '/')
2551                        q--;
2552                if (q == p)
2553                        break;
2554                *q = '\0';
2555                if (rmdir(git_path("%s", name)))
2556                        break;
2557        }
2558}
2559
2560/* make sure nobody touched the ref, and unlink */
2561static void prune_ref(struct ref_to_prune *r)
2562{
2563        struct ref_lock *lock = lock_ref_sha1(r->name + 5, r->sha1);
2564
2565        if (lock) {
2566                unlink_or_warn(git_path("%s", r->name));
2567                unlock_ref(lock);
2568                try_remove_empty_parents(r->name);
2569        }
2570}
2571
2572static void prune_refs(struct ref_to_prune *r)
2573{
2574        while (r) {
2575                prune_ref(r);
2576                r = r->next;
2577        }
2578}
2579
2580int pack_refs(unsigned int flags)
2581{
2582        struct pack_refs_cb_data cbdata;
2583
2584        memset(&cbdata, 0, sizeof(cbdata));
2585        cbdata.flags = flags;
2586
2587        lock_packed_refs(LOCK_DIE_ON_ERROR);
2588        cbdata.packed_refs = get_packed_refs(&ref_cache);
2589
2590        do_for_each_entry_in_dir(get_loose_refs(&ref_cache), 0,
2591                                 pack_if_possible_fn, &cbdata);
2592
2593        if (commit_packed_refs())
2594                die_errno("unable to overwrite old ref-pack file");
2595
2596        prune_refs(cbdata.ref_to_prune);
2597        return 0;
2598}
2599
2600/*
2601 * If entry is no longer needed in packed-refs, add it to the string
2602 * list pointed to by cb_data.  Reasons for deleting entries:
2603 *
2604 * - Entry is broken.
2605 * - Entry is overridden by a loose ref.
2606 * - Entry does not point at a valid object.
2607 *
2608 * In the first and third cases, also emit an error message because these
2609 * are indications of repository corruption.
2610 */
2611static int curate_packed_ref_fn(struct ref_entry *entry, void *cb_data)
2612{
2613        struct string_list *refs_to_delete = cb_data;
2614
2615        if (entry->flag & REF_ISBROKEN) {
2616                /* This shouldn't happen to packed refs. */
2617                error("%s is broken!", entry->name);
2618                string_list_append(refs_to_delete, entry->name);
2619                return 0;
2620        }
2621        if (!has_sha1_file(entry->u.value.sha1)) {
2622                unsigned char sha1[20];
2623                int flags;
2624
2625                if (read_ref_full(entry->name, sha1, 0, &flags))
2626                        /* We should at least have found the packed ref. */
2627                        die("Internal error");
2628                if ((flags & REF_ISSYMREF) || !(flags & REF_ISPACKED)) {
2629                        /*
2630                         * This packed reference is overridden by a
2631                         * loose reference, so it is OK that its value
2632                         * is no longer valid; for example, it might
2633                         * refer to an object that has been garbage
2634                         * collected.  For this purpose we don't even
2635                         * care whether the loose reference itself is
2636                         * invalid, broken, symbolic, etc.  Silently
2637                         * remove the packed reference.
2638                         */
2639                        string_list_append(refs_to_delete, entry->name);
2640                        return 0;
2641                }
2642                /*
2643                 * There is no overriding loose reference, so the fact
2644                 * that this reference doesn't refer to a valid object
2645                 * indicates some kind of repository corruption.
2646                 * Report the problem, then omit the reference from
2647                 * the output.
2648                 */
2649                error("%s does not point to a valid object!", entry->name);
2650                string_list_append(refs_to_delete, entry->name);
2651                return 0;
2652        }
2653
2654        return 0;
2655}
2656
2657int repack_without_refs(const char **refnames, int n)
2658{
2659        struct ref_dir *packed;
2660        struct string_list refs_to_delete = STRING_LIST_INIT_DUP;
2661        struct string_list_item *ref_to_delete;
2662        int i, removed = 0;
2663
2664        /* Look for a packed ref */
2665        for (i = 0; i < n; i++)
2666                if (get_packed_ref(refnames[i]))
2667                        break;
2668
2669        /* Avoid locking if we have nothing to do */
2670        if (i == n)
2671                return 0; /* no refname exists in packed refs */
2672
2673        if (lock_packed_refs(0)) {
2674                unable_to_lock_error(git_path("packed-refs"), errno);
2675                return error("cannot delete '%s' from packed refs", refnames[i]);
2676        }
2677        packed = get_packed_refs(&ref_cache);
2678
2679        /* Remove refnames from the cache */
2680        for (i = 0; i < n; i++)
2681                if (remove_entry(packed, refnames[i]) != -1)
2682                        removed = 1;
2683        if (!removed) {
2684                /*
2685                 * All packed entries disappeared while we were
2686                 * acquiring the lock.
2687                 */
2688                rollback_packed_refs();
2689                return 0;
2690        }
2691
2692        /* Remove any other accumulated cruft */
2693        do_for_each_entry_in_dir(packed, 0, curate_packed_ref_fn, &refs_to_delete);
2694        for_each_string_list_item(ref_to_delete, &refs_to_delete) {
2695                if (remove_entry(packed, ref_to_delete->string) == -1)
2696                        die("internal error");
2697        }
2698
2699        /* Write what remains */
2700        return commit_packed_refs();
2701}
2702
2703static int repack_without_ref(const char *refname)
2704{
2705        return repack_without_refs(&refname, 1);
2706}
2707
2708static int delete_ref_loose(struct ref_lock *lock, int flag)
2709{
2710        if (!(flag & REF_ISPACKED) || flag & REF_ISSYMREF) {
2711                /* loose */
2712                int err, i = strlen(lock->lk->filename) - 5; /* .lock */
2713
2714                lock->lk->filename[i] = 0;
2715                err = unlink_or_warn(lock->lk->filename);
2716                lock->lk->filename[i] = '.';
2717                if (err && errno != ENOENT)
2718                        return 1;
2719        }
2720        return 0;
2721}
2722
2723int delete_ref(const char *refname, const unsigned char *sha1, int delopt)
2724{
2725        struct ref_lock *lock;
2726        int ret = 0, flag = 0;
2727
2728        lock = lock_ref_sha1_basic(refname, sha1, delopt, &flag);
2729        if (!lock)
2730                return 1;
2731        ret |= delete_ref_loose(lock, flag);
2732
2733        /* removing the loose one could have resurrected an earlier
2734         * packed one.  Also, if it was not loose we need to repack
2735         * without it.
2736         */
2737        ret |= repack_without_ref(lock->ref_name);
2738
2739        unlink_or_warn(git_path("logs/%s", lock->ref_name));
2740        clear_loose_ref_cache(&ref_cache);
2741        unlock_ref(lock);
2742        return ret;
2743}
2744
2745/*
2746 * People using contrib's git-new-workdir have .git/logs/refs ->
2747 * /some/other/path/.git/logs/refs, and that may live on another device.
2748 *
2749 * IOW, to avoid cross device rename errors, the temporary renamed log must
2750 * live into logs/refs.
2751 */
2752#define TMP_RENAMED_LOG  "logs/refs/.tmp-renamed-log"
2753
2754static int rename_tmp_log(const char *newrefname)
2755{
2756        int attempts_remaining = 4;
2757
2758 retry:
2759        switch (safe_create_leading_directories(git_path("logs/%s", newrefname))) {
2760        case SCLD_OK:
2761                break; /* success */
2762        case SCLD_VANISHED:
2763                if (--attempts_remaining > 0)
2764                        goto retry;
2765                /* fall through */
2766        default:
2767                error("unable to create directory for %s", newrefname);
2768                return -1;
2769        }
2770
2771        if (rename(git_path(TMP_RENAMED_LOG), git_path("logs/%s", newrefname))) {
2772                if ((errno==EISDIR || errno==ENOTDIR) && --attempts_remaining > 0) {
2773                        /*
2774                         * rename(a, b) when b is an existing
2775                         * directory ought to result in ISDIR, but
2776                         * Solaris 5.8 gives ENOTDIR.  Sheesh.
2777                         */
2778                        if (remove_empty_directories(git_path("logs/%s", newrefname))) {
2779                                error("Directory not empty: logs/%s", newrefname);
2780                                return -1;
2781                        }
2782                        goto retry;
2783                } else if (errno == ENOENT && --attempts_remaining > 0) {
2784                        /*
2785                         * Maybe another process just deleted one of
2786                         * the directories in the path to newrefname.
2787                         * Try again from the beginning.
2788                         */
2789                        goto retry;
2790                } else {
2791                        error("unable to move logfile "TMP_RENAMED_LOG" to logs/%s: %s",
2792                                newrefname, strerror(errno));
2793                        return -1;
2794                }
2795        }
2796        return 0;
2797}
2798
2799int rename_ref(const char *oldrefname, const char *newrefname, const char *logmsg)
2800{
2801        unsigned char sha1[20], orig_sha1[20];
2802        int flag = 0, logmoved = 0;
2803        struct ref_lock *lock;
2804        struct stat loginfo;
2805        int log = !lstat(git_path("logs/%s", oldrefname), &loginfo);
2806        const char *symref = NULL;
2807
2808        if (log && S_ISLNK(loginfo.st_mode))
2809                return error("reflog for %s is a symlink", oldrefname);
2810
2811        symref = resolve_ref_unsafe(oldrefname, orig_sha1, 1, &flag);
2812        if (flag & REF_ISSYMREF)
2813                return error("refname %s is a symbolic ref, renaming it is not supported",
2814                        oldrefname);
2815        if (!symref)
2816                return error("refname %s not found", oldrefname);
2817
2818        if (!is_refname_available(newrefname, oldrefname, get_packed_refs(&ref_cache)))
2819                return 1;
2820
2821        if (!is_refname_available(newrefname, oldrefname, get_loose_refs(&ref_cache)))
2822                return 1;
2823
2824        if (log && rename(git_path("logs/%s", oldrefname), git_path(TMP_RENAMED_LOG)))
2825                return error("unable to move logfile logs/%s to "TMP_RENAMED_LOG": %s",
2826                        oldrefname, strerror(errno));
2827
2828        if (delete_ref(oldrefname, orig_sha1, REF_NODEREF)) {
2829                error("unable to delete old %s", oldrefname);
2830                goto rollback;
2831        }
2832
2833        if (!read_ref_full(newrefname, sha1, 1, &flag) &&
2834            delete_ref(newrefname, sha1, REF_NODEREF)) {
2835                if (errno==EISDIR) {
2836                        if (remove_empty_directories(git_path("%s", newrefname))) {
2837                                error("Directory not empty: %s", newrefname);
2838                                goto rollback;
2839                        }
2840                } else {
2841                        error("unable to delete existing %s", newrefname);
2842                        goto rollback;
2843                }
2844        }
2845
2846        if (log && rename_tmp_log(newrefname))
2847                goto rollback;
2848
2849        logmoved = log;
2850
2851        lock = lock_ref_sha1_basic(newrefname, NULL, 0, NULL);
2852        if (!lock) {
2853                error("unable to lock %s for update", newrefname);
2854                goto rollback;
2855        }
2856        lock->force_write = 1;
2857        hashcpy(lock->old_sha1, orig_sha1);
2858        if (write_ref_sha1(lock, orig_sha1, logmsg)) {
2859                error("unable to write current sha1 into %s", newrefname);
2860                goto rollback;
2861        }
2862
2863        return 0;
2864
2865 rollback:
2866        lock = lock_ref_sha1_basic(oldrefname, NULL, 0, NULL);
2867        if (!lock) {
2868                error("unable to lock %s for rollback", oldrefname);
2869                goto rollbacklog;
2870        }
2871
2872        lock->force_write = 1;
2873        flag = log_all_ref_updates;
2874        log_all_ref_updates = 0;
2875        if (write_ref_sha1(lock, orig_sha1, NULL))
2876                error("unable to write current sha1 into %s", oldrefname);
2877        log_all_ref_updates = flag;
2878
2879 rollbacklog:
2880        if (logmoved && rename(git_path("logs/%s", newrefname), git_path("logs/%s", oldrefname)))
2881                error("unable to restore logfile %s from %s: %s",
2882                        oldrefname, newrefname, strerror(errno));
2883        if (!logmoved && log &&
2884            rename(git_path(TMP_RENAMED_LOG), git_path("logs/%s", oldrefname)))
2885                error("unable to restore logfile %s from "TMP_RENAMED_LOG": %s",
2886                        oldrefname, strerror(errno));
2887
2888        return 1;
2889}
2890
2891int close_ref(struct ref_lock *lock)
2892{
2893        if (close_lock_file(lock->lk))
2894                return -1;
2895        lock->lock_fd = -1;
2896        return 0;
2897}
2898
2899int commit_ref(struct ref_lock *lock)
2900{
2901        if (commit_lock_file(lock->lk))
2902                return -1;
2903        lock->lock_fd = -1;
2904        return 0;
2905}
2906
2907void unlock_ref(struct ref_lock *lock)
2908{
2909        /* Do not free lock->lk -- atexit() still looks at them */
2910        if (lock->lk)
2911                rollback_lock_file(lock->lk);
2912        free(lock->ref_name);
2913        free(lock->orig_ref_name);
2914        free(lock);
2915}
2916
2917/*
2918 * copy the reflog message msg to buf, which has been allocated sufficiently
2919 * large, while cleaning up the whitespaces.  Especially, convert LF to space,
2920 * because reflog file is one line per entry.
2921 */
2922static int copy_msg(char *buf, const char *msg)
2923{
2924        char *cp = buf;
2925        char c;
2926        int wasspace = 1;
2927
2928        *cp++ = '\t';
2929        while ((c = *msg++)) {
2930                if (wasspace && isspace(c))
2931                        continue;
2932                wasspace = isspace(c);
2933                if (wasspace)
2934                        c = ' ';
2935                *cp++ = c;
2936        }
2937        while (buf < cp && isspace(cp[-1]))
2938                cp--;
2939        *cp++ = '\n';
2940        return cp - buf;
2941}
2942
2943int log_ref_setup(const char *refname, char *logfile, int bufsize)
2944{
2945        int logfd, oflags = O_APPEND | O_WRONLY;
2946
2947        git_snpath(logfile, bufsize, "logs/%s", refname);
2948        if (log_all_ref_updates &&
2949            (starts_with(refname, "refs/heads/") ||
2950             starts_with(refname, "refs/remotes/") ||
2951             starts_with(refname, "refs/notes/") ||
2952             !strcmp(refname, "HEAD"))) {
2953                if (safe_create_leading_directories(logfile) < 0)
2954                        return error("unable to create directory for %s",
2955                                     logfile);
2956                oflags |= O_CREAT;
2957        }
2958
2959        logfd = open(logfile, oflags, 0666);
2960        if (logfd < 0) {
2961                if (!(oflags & O_CREAT) && errno == ENOENT)
2962                        return 0;
2963
2964                if ((oflags & O_CREAT) && errno == EISDIR) {
2965                        if (remove_empty_directories(logfile)) {
2966                                return error("There are still logs under '%s'",
2967                                             logfile);
2968                        }
2969                        logfd = open(logfile, oflags, 0666);
2970                }
2971
2972                if (logfd < 0)
2973                        return error("Unable to append to %s: %s",
2974                                     logfile, strerror(errno));
2975        }
2976
2977        adjust_shared_perm(logfile);
2978        close(logfd);
2979        return 0;
2980}
2981
2982static int log_ref_write(const char *refname, const unsigned char *old_sha1,
2983                         const unsigned char *new_sha1, const char *msg)
2984{
2985        int logfd, result, written, oflags = O_APPEND | O_WRONLY;
2986        unsigned maxlen, len;
2987        int msglen;
2988        char log_file[PATH_MAX];
2989        char *logrec;
2990        const char *committer;
2991
2992        if (log_all_ref_updates < 0)
2993                log_all_ref_updates = !is_bare_repository();
2994
2995        result = log_ref_setup(refname, log_file, sizeof(log_file));
2996        if (result)
2997                return result;
2998
2999        logfd = open(log_file, oflags);
3000        if (logfd < 0)
3001                return 0;
3002        msglen = msg ? strlen(msg) : 0;
3003        committer = git_committer_info(0);
3004        maxlen = strlen(committer) + msglen + 100;
3005        logrec = xmalloc(maxlen);
3006        len = sprintf(logrec, "%s %s %s\n",
3007                      sha1_to_hex(old_sha1),
3008                      sha1_to_hex(new_sha1),
3009                      committer);
3010        if (msglen)
3011                len += copy_msg(logrec + len - 1, msg) - 1;
3012        written = len <= maxlen ? write_in_full(logfd, logrec, len) : -1;
3013        free(logrec);
3014        if (close(logfd) != 0 || written != len)
3015                return error("Unable to append to %s", log_file);
3016        return 0;
3017}
3018
3019static int is_branch(const char *refname)
3020{
3021        return !strcmp(refname, "HEAD") || starts_with(refname, "refs/heads/");
3022}
3023
3024int write_ref_sha1(struct ref_lock *lock,
3025        const unsigned char *sha1, const char *logmsg)
3026{
3027        static char term = '\n';
3028        struct object *o;
3029
3030        if (!lock)
3031                return -1;
3032        if (!lock->force_write && !hashcmp(lock->old_sha1, sha1)) {
3033                unlock_ref(lock);
3034                return 0;
3035        }
3036        o = parse_object(sha1);
3037        if (!o) {
3038                error("Trying to write ref %s with nonexistent object %s",
3039                        lock->ref_name, sha1_to_hex(sha1));
3040                unlock_ref(lock);
3041                return -1;
3042        }
3043        if (o->type != OBJ_COMMIT && is_branch(lock->ref_name)) {
3044                error("Trying to write non-commit object %s to branch %s",
3045                        sha1_to_hex(sha1), lock->ref_name);
3046                unlock_ref(lock);
3047                return -1;
3048        }
3049        if (write_in_full(lock->lock_fd, sha1_to_hex(sha1), 40) != 40 ||
3050            write_in_full(lock->lock_fd, &term, 1) != 1
3051                || close_ref(lock) < 0) {
3052                error("Couldn't write %s", lock->lk->filename);
3053                unlock_ref(lock);
3054                return -1;
3055        }
3056        clear_loose_ref_cache(&ref_cache);
3057        if (log_ref_write(lock->ref_name, lock->old_sha1, sha1, logmsg) < 0 ||
3058            (strcmp(lock->ref_name, lock->orig_ref_name) &&
3059             log_ref_write(lock->orig_ref_name, lock->old_sha1, sha1, logmsg) < 0)) {
3060                unlock_ref(lock);
3061                return -1;
3062        }
3063        if (strcmp(lock->orig_ref_name, "HEAD") != 0) {
3064                /*
3065                 * Special hack: If a branch is updated directly and HEAD
3066                 * points to it (may happen on the remote side of a push
3067                 * for example) then logically the HEAD reflog should be
3068                 * updated too.
3069                 * A generic solution implies reverse symref information,
3070                 * but finding all symrefs pointing to the given branch
3071                 * would be rather costly for this rare event (the direct
3072                 * update of a branch) to be worth it.  So let's cheat and
3073                 * check with HEAD only which should cover 99% of all usage
3074                 * scenarios (even 100% of the default ones).
3075                 */
3076                unsigned char head_sha1[20];
3077                int head_flag;
3078                const char *head_ref;
3079                head_ref = resolve_ref_unsafe("HEAD", head_sha1, 1, &head_flag);
3080                if (head_ref && (head_flag & REF_ISSYMREF) &&
3081                    !strcmp(head_ref, lock->ref_name))
3082                        log_ref_write("HEAD", lock->old_sha1, sha1, logmsg);
3083        }
3084        if (commit_ref(lock)) {
3085                error("Couldn't set %s", lock->ref_name);
3086                unlock_ref(lock);
3087                return -1;
3088        }
3089        unlock_ref(lock);
3090        return 0;
3091}
3092
3093int create_symref(const char *ref_target, const char *refs_heads_master,
3094                  const char *logmsg)
3095{
3096        const char *lockpath;
3097        char ref[1000];
3098        int fd, len, written;
3099        char *git_HEAD = git_pathdup("%s", ref_target);
3100        unsigned char old_sha1[20], new_sha1[20];
3101
3102        if (logmsg && read_ref(ref_target, old_sha1))
3103                hashclr(old_sha1);
3104
3105        if (safe_create_leading_directories(git_HEAD) < 0)
3106                return error("unable to create directory for %s", git_HEAD);
3107
3108#ifndef NO_SYMLINK_HEAD
3109        if (prefer_symlink_refs) {
3110                unlink(git_HEAD);
3111                if (!symlink(refs_heads_master, git_HEAD))
3112                        goto done;
3113                fprintf(stderr, "no symlink - falling back to symbolic ref\n");
3114        }
3115#endif
3116
3117        len = snprintf(ref, sizeof(ref), "ref: %s\n", refs_heads_master);
3118        if (sizeof(ref) <= len) {
3119                error("refname too long: %s", refs_heads_master);
3120                goto error_free_return;
3121        }
3122        lockpath = mkpath("%s.lock", git_HEAD);
3123        fd = open(lockpath, O_CREAT | O_EXCL | O_WRONLY, 0666);
3124        if (fd < 0) {
3125                error("Unable to open %s for writing", lockpath);
3126                goto error_free_return;
3127        }
3128        written = write_in_full(fd, ref, len);
3129        if (close(fd) != 0 || written != len) {
3130                error("Unable to write to %s", lockpath);
3131                goto error_unlink_return;
3132        }
3133        if (rename(lockpath, git_HEAD) < 0) {
3134                error("Unable to create %s", git_HEAD);
3135                goto error_unlink_return;
3136        }
3137        if (adjust_shared_perm(git_HEAD)) {
3138                error("Unable to fix permissions on %s", lockpath);
3139        error_unlink_return:
3140                unlink_or_warn(lockpath);
3141        error_free_return:
3142                free(git_HEAD);
3143                return -1;
3144        }
3145
3146#ifndef NO_SYMLINK_HEAD
3147        done:
3148#endif
3149        if (logmsg && !read_ref(refs_heads_master, new_sha1))
3150                log_ref_write(ref_target, old_sha1, new_sha1, logmsg);
3151
3152        free(git_HEAD);
3153        return 0;
3154}
3155
3156struct read_ref_at_cb {
3157        const char *refname;
3158        unsigned long at_time;
3159        int cnt;
3160        int reccnt;
3161        unsigned char *sha1;
3162        int found_it;
3163
3164        unsigned char osha1[20];
3165        unsigned char nsha1[20];
3166        int tz;
3167        unsigned long date;
3168        char **msg;
3169        unsigned long *cutoff_time;
3170        int *cutoff_tz;
3171        int *cutoff_cnt;
3172};
3173
3174static int read_ref_at_ent(unsigned char *osha1, unsigned char *nsha1,
3175                const char *email, unsigned long timestamp, int tz,
3176                const char *message, void *cb_data)
3177{
3178        struct read_ref_at_cb *cb = cb_data;
3179
3180        cb->reccnt++;
3181        cb->tz = tz;
3182        cb->date = timestamp;
3183
3184        if (timestamp <= cb->at_time || cb->cnt == 0) {
3185                if (cb->msg)
3186                        *cb->msg = xstrdup(message);
3187                if (cb->cutoff_time)
3188                        *cb->cutoff_time = timestamp;
3189                if (cb->cutoff_tz)
3190                        *cb->cutoff_tz = tz;
3191                if (cb->cutoff_cnt)
3192                        *cb->cutoff_cnt = cb->reccnt - 1;
3193                /*
3194                 * we have not yet updated cb->[n|o]sha1 so they still
3195                 * hold the values for the previous record.
3196                 */
3197                if (!is_null_sha1(cb->osha1)) {
3198                        hashcpy(cb->sha1, nsha1);
3199                        if (hashcmp(cb->osha1, nsha1))
3200                                warning("Log for ref %s has gap after %s.",
3201                                        cb->refname, show_date(cb->date, cb->tz, DATE_RFC2822));
3202                }
3203                else if (cb->date == cb->at_time)
3204                        hashcpy(cb->sha1, nsha1);
3205                else if (hashcmp(nsha1, cb->sha1))
3206                        warning("Log for ref %s unexpectedly ended on %s.",
3207                                cb->refname, show_date(cb->date, cb->tz,
3208                                                   DATE_RFC2822));
3209                hashcpy(cb->osha1, osha1);
3210                hashcpy(cb->nsha1, nsha1);
3211                cb->found_it = 1;
3212                return 1;
3213        }
3214        hashcpy(cb->osha1, osha1);
3215        hashcpy(cb->nsha1, nsha1);
3216        if (cb->cnt > 0)
3217                cb->cnt--;
3218        return 0;
3219}
3220
3221static int read_ref_at_ent_oldest(unsigned char *osha1, unsigned char *nsha1,
3222                                  const char *email, unsigned long timestamp,
3223                                  int tz, const char *message, void *cb_data)
3224{
3225        struct read_ref_at_cb *cb = cb_data;
3226
3227        if (cb->msg)
3228                *cb->msg = xstrdup(message);
3229        if (cb->cutoff_time)
3230                *cb->cutoff_time = timestamp;
3231        if (cb->cutoff_tz)
3232                *cb->cutoff_tz = tz;
3233        if (cb->cutoff_cnt)
3234                *cb->cutoff_cnt = cb->reccnt;
3235        hashcpy(cb->sha1, osha1);
3236        if (is_null_sha1(cb->sha1))
3237                hashcpy(cb->sha1, nsha1);
3238        /* We just want the first entry */
3239        return 1;
3240}
3241
3242int read_ref_at(const char *refname, unsigned long at_time, int cnt,
3243                unsigned char *sha1, char **msg,
3244                unsigned long *cutoff_time, int *cutoff_tz, int *cutoff_cnt)
3245{
3246        struct read_ref_at_cb cb;
3247
3248        memset(&cb, 0, sizeof(cb));
3249        cb.refname = refname;
3250        cb.at_time = at_time;
3251        cb.cnt = cnt;
3252        cb.msg = msg;
3253        cb.cutoff_time = cutoff_time;
3254        cb.cutoff_tz = cutoff_tz;
3255        cb.cutoff_cnt = cutoff_cnt;
3256        cb.sha1 = sha1;
3257
3258        for_each_reflog_ent_reverse(refname, read_ref_at_ent, &cb);
3259
3260        if (!cb.reccnt)
3261                die("Log for %s is empty.", refname);
3262        if (cb.found_it)
3263                return 0;
3264
3265        for_each_reflog_ent(refname, read_ref_at_ent_oldest, &cb);
3266
3267        return 1;
3268}
3269
3270int reflog_exists(const char *refname)
3271{
3272        struct stat st;
3273
3274        return !lstat(git_path("logs/%s", refname), &st) &&
3275                S_ISREG(st.st_mode);
3276}
3277
3278int delete_reflog(const char *refname)
3279{
3280        return remove_path(git_path("logs/%s", refname));
3281}
3282
3283static int show_one_reflog_ent(struct strbuf *sb, each_reflog_ent_fn fn, void *cb_data)
3284{
3285        unsigned char osha1[20], nsha1[20];
3286        char *email_end, *message;
3287        unsigned long timestamp;
3288        int tz;
3289
3290        /* old SP new SP name <email> SP time TAB msg LF */
3291        if (sb->len < 83 || sb->buf[sb->len - 1] != '\n' ||
3292            get_sha1_hex(sb->buf, osha1) || sb->buf[40] != ' ' ||
3293            get_sha1_hex(sb->buf + 41, nsha1) || sb->buf[81] != ' ' ||
3294            !(email_end = strchr(sb->buf + 82, '>')) ||
3295            email_end[1] != ' ' ||
3296            !(timestamp = strtoul(email_end + 2, &message, 10)) ||
3297            !message || message[0] != ' ' ||
3298            (message[1] != '+' && message[1] != '-') ||
3299            !isdigit(message[2]) || !isdigit(message[3]) ||
3300            !isdigit(message[4]) || !isdigit(message[5]))
3301                return 0; /* corrupt? */
3302        email_end[1] = '\0';
3303        tz = strtol(message + 1, NULL, 10);
3304        if (message[6] != '\t')
3305                message += 6;
3306        else
3307                message += 7;
3308        return fn(osha1, nsha1, sb->buf + 82, timestamp, tz, message, cb_data);
3309}
3310
3311static char *find_beginning_of_line(char *bob, char *scan)
3312{
3313        while (bob < scan && *(--scan) != '\n')
3314                ; /* keep scanning backwards */
3315        /*
3316         * Return either beginning of the buffer, or LF at the end of
3317         * the previous line.
3318         */
3319        return scan;
3320}
3321
3322int for_each_reflog_ent_reverse(const char *refname, each_reflog_ent_fn fn, void *cb_data)
3323{
3324        struct strbuf sb = STRBUF_INIT;
3325        FILE *logfp;
3326        long pos;
3327        int ret = 0, at_tail = 1;
3328
3329        logfp = fopen(git_path("logs/%s", refname), "r");
3330        if (!logfp)
3331                return -1;
3332
3333        /* Jump to the end */
3334        if (fseek(logfp, 0, SEEK_END) < 0)
3335                return error("cannot seek back reflog for %s: %s",
3336                             refname, strerror(errno));
3337        pos = ftell(logfp);
3338        while (!ret && 0 < pos) {
3339                int cnt;
3340                size_t nread;
3341                char buf[BUFSIZ];
3342                char *endp, *scanp;
3343
3344                /* Fill next block from the end */
3345                cnt = (sizeof(buf) < pos) ? sizeof(buf) : pos;
3346                if (fseek(logfp, pos - cnt, SEEK_SET))
3347                        return error("cannot seek back reflog for %s: %s",
3348                                     refname, strerror(errno));
3349                nread = fread(buf, cnt, 1, logfp);
3350                if (nread != 1)
3351                        return error("cannot read %d bytes from reflog for %s: %s",
3352                                     cnt, refname, strerror(errno));
3353                pos -= cnt;
3354
3355                scanp = endp = buf + cnt;
3356                if (at_tail && scanp[-1] == '\n')
3357                        /* Looking at the final LF at the end of the file */
3358                        scanp--;
3359                at_tail = 0;
3360
3361                while (buf < scanp) {
3362                        /*
3363                         * terminating LF of the previous line, or the beginning
3364                         * of the buffer.
3365                         */
3366                        char *bp;
3367
3368                        bp = find_beginning_of_line(buf, scanp);
3369
3370                        if (*bp != '\n') {
3371                                strbuf_splice(&sb, 0, 0, buf, endp - buf);
3372                                if (pos)
3373                                        break; /* need to fill another block */
3374                                scanp = buf - 1; /* leave loop */
3375                        } else {
3376                                /*
3377                                 * (bp + 1) thru endp is the beginning of the
3378                                 * current line we have in sb
3379                                 */
3380                                strbuf_splice(&sb, 0, 0, bp + 1, endp - (bp + 1));
3381                                scanp = bp;
3382                                endp = bp + 1;
3383                        }
3384                        ret = show_one_reflog_ent(&sb, fn, cb_data);
3385                        strbuf_reset(&sb);
3386                        if (ret)
3387                                break;
3388                }
3389
3390        }
3391        if (!ret && sb.len)
3392                ret = show_one_reflog_ent(&sb, fn, cb_data);
3393
3394        fclose(logfp);
3395        strbuf_release(&sb);
3396        return ret;
3397}
3398
3399int for_each_reflog_ent(const char *refname, each_reflog_ent_fn fn, void *cb_data)
3400{
3401        FILE *logfp;
3402        struct strbuf sb = STRBUF_INIT;
3403        int ret = 0;
3404
3405        logfp = fopen(git_path("logs/%s", refname), "r");
3406        if (!logfp)
3407                return -1;
3408
3409        while (!ret && !strbuf_getwholeline(&sb, logfp, '\n'))
3410                ret = show_one_reflog_ent(&sb, fn, cb_data);
3411        fclose(logfp);
3412        strbuf_release(&sb);
3413        return ret;
3414}
3415/*
3416 * Call fn for each reflog in the namespace indicated by name.  name
3417 * must be empty or end with '/'.  Name will be used as a scratch
3418 * space, but its contents will be restored before return.
3419 */
3420static int do_for_each_reflog(struct strbuf *name, each_ref_fn fn, void *cb_data)
3421{
3422        DIR *d = opendir(git_path("logs/%s", name->buf));
3423        int retval = 0;
3424        struct dirent *de;
3425        int oldlen = name->len;
3426
3427        if (!d)
3428                return name->len ? errno : 0;
3429
3430        while ((de = readdir(d)) != NULL) {
3431                struct stat st;
3432
3433                if (de->d_name[0] == '.')
3434                        continue;
3435                if (ends_with(de->d_name, ".lock"))
3436                        continue;
3437                strbuf_addstr(name, de->d_name);
3438                if (stat(git_path("logs/%s", name->buf), &st) < 0) {
3439                        ; /* silently ignore */
3440                } else {
3441                        if (S_ISDIR(st.st_mode)) {
3442                                strbuf_addch(name, '/');
3443                                retval = do_for_each_reflog(name, fn, cb_data);
3444                        } else {
3445                                unsigned char sha1[20];
3446                                if (read_ref_full(name->buf, sha1, 0, NULL))
3447                                        retval = error("bad ref for %s", name->buf);
3448                                else
3449                                        retval = fn(name->buf, sha1, 0, cb_data);
3450                        }
3451                        if (retval)
3452                                break;
3453                }
3454                strbuf_setlen(name, oldlen);
3455        }
3456        closedir(d);
3457        return retval;
3458}
3459
3460int for_each_reflog(each_ref_fn fn, void *cb_data)
3461{
3462        int retval;
3463        struct strbuf name;
3464        strbuf_init(&name, PATH_MAX);
3465        retval = do_for_each_reflog(&name, fn, cb_data);
3466        strbuf_release(&name);
3467        return retval;
3468}
3469
3470static struct ref_lock *update_ref_lock(const char *refname,
3471                                        const unsigned char *oldval,
3472                                        int flags, int *type_p,
3473                                        enum action_on_err onerr)
3474{
3475        struct ref_lock *lock;
3476        lock = lock_any_ref_for_update(refname, oldval, flags, type_p);
3477        if (!lock) {
3478                const char *str = "Cannot lock the ref '%s'.";
3479                switch (onerr) {
3480                case UPDATE_REFS_MSG_ON_ERR: error(str, refname); break;
3481                case UPDATE_REFS_DIE_ON_ERR: die(str, refname); break;
3482                case UPDATE_REFS_QUIET_ON_ERR: break;
3483                }
3484        }
3485        return lock;
3486}
3487
3488static int update_ref_write(const char *action, const char *refname,
3489                            const unsigned char *sha1, struct ref_lock *lock,
3490                            enum action_on_err onerr)
3491{
3492        if (write_ref_sha1(lock, sha1, action) < 0) {
3493                const char *str = "Cannot update the ref '%s'.";
3494                switch (onerr) {
3495                case UPDATE_REFS_MSG_ON_ERR: error(str, refname); break;
3496                case UPDATE_REFS_DIE_ON_ERR: die(str, refname); break;
3497                case UPDATE_REFS_QUIET_ON_ERR: break;
3498                }
3499                return 1;
3500        }
3501        return 0;
3502}
3503
3504/**
3505 * Information needed for a single ref update.  Set new_sha1 to the
3506 * new value or to zero to delete the ref.  To check the old value
3507 * while locking the ref, set have_old to 1 and set old_sha1 to the
3508 * value or to zero to ensure the ref does not exist before update.
3509 */
3510struct ref_update {
3511        unsigned char new_sha1[20];
3512        unsigned char old_sha1[20];
3513        int flags; /* REF_NODEREF? */
3514        int have_old; /* 1 if old_sha1 is valid, 0 otherwise */
3515        struct ref_lock *lock;
3516        int type;
3517        const char refname[FLEX_ARRAY];
3518};
3519
3520/*
3521 * Data structure for holding a reference transaction, which can
3522 * consist of checks and updates to multiple references, carried out
3523 * as atomically as possible.  This structure is opaque to callers.
3524 */
3525struct ref_transaction {
3526        struct ref_update **updates;
3527        size_t alloc;
3528        size_t nr;
3529};
3530
3531struct ref_transaction *ref_transaction_begin(void)
3532{
3533        return xcalloc(1, sizeof(struct ref_transaction));
3534}
3535
3536static void ref_transaction_free(struct ref_transaction *transaction)
3537{
3538        int i;
3539
3540        for (i = 0; i < transaction->nr; i++)
3541                free(transaction->updates[i]);
3542
3543        free(transaction->updates);
3544        free(transaction);
3545}
3546
3547void ref_transaction_rollback(struct ref_transaction *transaction)
3548{
3549        ref_transaction_free(transaction);
3550}
3551
3552static struct ref_update *add_update(struct ref_transaction *transaction,
3553                                     const char *refname)
3554{
3555        size_t len = strlen(refname);
3556        struct ref_update *update = xcalloc(1, sizeof(*update) + len + 1);
3557
3558        strcpy((char *)update->refname, refname);
3559        ALLOC_GROW(transaction->updates, transaction->nr + 1, transaction->alloc);
3560        transaction->updates[transaction->nr++] = update;
3561        return update;
3562}
3563
3564void ref_transaction_update(struct ref_transaction *transaction,
3565                            const char *refname,
3566                            unsigned char *new_sha1, unsigned char *old_sha1,
3567                            int flags, int have_old)
3568{
3569        struct ref_update *update = add_update(transaction, refname);
3570
3571        hashcpy(update->new_sha1, new_sha1);
3572        update->flags = flags;
3573        update->have_old = have_old;
3574        if (have_old)
3575                hashcpy(update->old_sha1, old_sha1);
3576}
3577
3578void ref_transaction_create(struct ref_transaction *transaction,
3579                            const char *refname,
3580                            unsigned char *new_sha1,
3581                            int flags)
3582{
3583        struct ref_update *update = add_update(transaction, refname);
3584
3585        assert(!is_null_sha1(new_sha1));
3586        hashcpy(update->new_sha1, new_sha1);
3587        hashclr(update->old_sha1);
3588        update->flags = flags;
3589        update->have_old = 1;
3590}
3591
3592void ref_transaction_delete(struct ref_transaction *transaction,
3593                            const char *refname,
3594                            unsigned char *old_sha1,
3595                            int flags, int have_old)
3596{
3597        struct ref_update *update = add_update(transaction, refname);
3598
3599        update->flags = flags;
3600        update->have_old = have_old;
3601        if (have_old) {
3602                assert(!is_null_sha1(old_sha1));
3603                hashcpy(update->old_sha1, old_sha1);
3604        }
3605}
3606
3607int update_ref(const char *action, const char *refname,
3608               const unsigned char *sha1, const unsigned char *oldval,
3609               int flags, enum action_on_err onerr)
3610{
3611        struct ref_lock *lock;
3612        lock = update_ref_lock(refname, oldval, flags, NULL, onerr);
3613        if (!lock)
3614                return 1;
3615        return update_ref_write(action, refname, sha1, lock, onerr);
3616}
3617
3618static int ref_update_compare(const void *r1, const void *r2)
3619{
3620        const struct ref_update * const *u1 = r1;
3621        const struct ref_update * const *u2 = r2;
3622        return strcmp((*u1)->refname, (*u2)->refname);
3623}
3624
3625static int ref_update_reject_duplicates(struct ref_update **updates, int n,
3626                                        enum action_on_err onerr)
3627{
3628        int i;
3629        for (i = 1; i < n; i++)
3630                if (!strcmp(updates[i - 1]->refname, updates[i]->refname)) {
3631                        const char *str =
3632                                "Multiple updates for ref '%s' not allowed.";
3633                        switch (onerr) {
3634                        case UPDATE_REFS_MSG_ON_ERR:
3635                                error(str, updates[i]->refname); break;
3636                        case UPDATE_REFS_DIE_ON_ERR:
3637                                die(str, updates[i]->refname); break;
3638                        case UPDATE_REFS_QUIET_ON_ERR:
3639                                break;
3640                        }
3641                        return 1;
3642                }
3643        return 0;
3644}
3645
3646int ref_transaction_commit(struct ref_transaction *transaction,
3647                           const char *msg, enum action_on_err onerr)
3648{
3649        int ret = 0, delnum = 0, i;
3650        const char **delnames;
3651        int n = transaction->nr;
3652        struct ref_update **updates = transaction->updates;
3653
3654        if (!n)
3655                return 0;
3656
3657        /* Allocate work space */
3658        delnames = xmalloc(sizeof(*delnames) * n);
3659
3660        /* Copy, sort, and reject duplicate refs */
3661        qsort(updates, n, sizeof(*updates), ref_update_compare);
3662        ret = ref_update_reject_duplicates(updates, n, onerr);
3663        if (ret)
3664                goto cleanup;
3665
3666        /* Acquire all locks while verifying old values */
3667        for (i = 0; i < n; i++) {
3668                struct ref_update *update = updates[i];
3669
3670                update->lock = update_ref_lock(update->refname,
3671                                               (update->have_old ?
3672                                                update->old_sha1 : NULL),
3673                                               update->flags,
3674                                               &update->type, onerr);
3675                if (!update->lock) {
3676                        ret = 1;
3677                        goto cleanup;
3678                }
3679        }
3680
3681        /* Perform updates first so live commits remain referenced */
3682        for (i = 0; i < n; i++) {
3683                struct ref_update *update = updates[i];
3684
3685                if (!is_null_sha1(update->new_sha1)) {
3686                        ret = update_ref_write(msg,
3687                                               update->refname,
3688                                               update->new_sha1,
3689                                               update->lock, onerr);
3690                        update->lock = NULL; /* freed by update_ref_write */
3691                        if (ret)
3692                                goto cleanup;
3693                }
3694        }
3695
3696        /* Perform deletes now that updates are safely completed */
3697        for (i = 0; i < n; i++) {
3698                struct ref_update *update = updates[i];
3699
3700                if (update->lock) {
3701                        delnames[delnum++] = update->lock->ref_name;
3702                        ret |= delete_ref_loose(update->lock, update->type);
3703                }
3704        }
3705
3706        ret |= repack_without_refs(delnames, delnum);
3707        for (i = 0; i < delnum; i++)
3708                unlink_or_warn(git_path("logs/%s", delnames[i]));
3709        clear_loose_ref_cache(&ref_cache);
3710
3711cleanup:
3712        for (i = 0; i < n; i++)
3713                if (updates[i]->lock)
3714                        unlock_ref(updates[i]->lock);
3715        free(delnames);
3716        ref_transaction_free(transaction);
3717        return ret;
3718}
3719
3720char *shorten_unambiguous_ref(const char *refname, int strict)
3721{
3722        int i;
3723        static char **scanf_fmts;
3724        static int nr_rules;
3725        char *short_name;
3726
3727        if (!nr_rules) {
3728                /*
3729                 * Pre-generate scanf formats from ref_rev_parse_rules[].
3730                 * Generate a format suitable for scanf from a
3731                 * ref_rev_parse_rules rule by interpolating "%s" at the
3732                 * location of the "%.*s".
3733                 */
3734                size_t total_len = 0;
3735                size_t offset = 0;
3736
3737                /* the rule list is NULL terminated, count them first */
3738                for (nr_rules = 0; ref_rev_parse_rules[nr_rules]; nr_rules++)
3739                        /* -2 for strlen("%.*s") - strlen("%s"); +1 for NUL */
3740                        total_len += strlen(ref_rev_parse_rules[nr_rules]) - 2 + 1;
3741
3742                scanf_fmts = xmalloc(nr_rules * sizeof(char *) + total_len);
3743
3744                offset = 0;
3745                for (i = 0; i < nr_rules; i++) {
3746                        assert(offset < total_len);
3747                        scanf_fmts[i] = (char *)&scanf_fmts[nr_rules] + offset;
3748                        offset += snprintf(scanf_fmts[i], total_len - offset,
3749                                           ref_rev_parse_rules[i], 2, "%s") + 1;
3750                }
3751        }
3752
3753        /* bail out if there are no rules */
3754        if (!nr_rules)
3755                return xstrdup(refname);
3756
3757        /* buffer for scanf result, at most refname must fit */
3758        short_name = xstrdup(refname);
3759
3760        /* skip first rule, it will always match */
3761        for (i = nr_rules - 1; i > 0 ; --i) {
3762                int j;
3763                int rules_to_fail = i;
3764                int short_name_len;
3765
3766                if (1 != sscanf(refname, scanf_fmts[i], short_name))
3767                        continue;
3768
3769                short_name_len = strlen(short_name);
3770
3771                /*
3772                 * in strict mode, all (except the matched one) rules
3773                 * must fail to resolve to a valid non-ambiguous ref
3774                 */
3775                if (strict)
3776                        rules_to_fail = nr_rules;
3777
3778                /*
3779                 * check if the short name resolves to a valid ref,
3780                 * but use only rules prior to the matched one
3781                 */
3782                for (j = 0; j < rules_to_fail; j++) {
3783                        const char *rule = ref_rev_parse_rules[j];
3784                        char refname[PATH_MAX];
3785
3786                        /* skip matched rule */
3787                        if (i == j)
3788                                continue;
3789
3790                        /*
3791                         * the short name is ambiguous, if it resolves
3792                         * (with this previous rule) to a valid ref
3793                         * read_ref() returns 0 on success
3794                         */
3795                        mksnpath(refname, sizeof(refname),
3796                                 rule, short_name_len, short_name);
3797                        if (ref_exists(refname))
3798                                break;
3799                }
3800
3801                /*
3802                 * short name is non-ambiguous if all previous rules
3803                 * haven't resolved to a valid ref
3804                 */
3805                if (j == rules_to_fail)
3806                        return short_name;
3807        }
3808
3809        free(short_name);
3810        return xstrdup(refname);
3811}
3812
3813static struct string_list *hide_refs;
3814
3815int parse_hide_refs_config(const char *var, const char *value, const char *section)
3816{
3817        if (!strcmp("transfer.hiderefs", var) ||
3818            /* NEEDSWORK: use parse_config_key() once both are merged */
3819            (starts_with(var, section) && var[strlen(section)] == '.' &&
3820             !strcmp(var + strlen(section), ".hiderefs"))) {
3821                char *ref;
3822                int len;
3823
3824                if (!value)
3825                        return config_error_nonbool(var);
3826                ref = xstrdup(value);
3827                len = strlen(ref);
3828                while (len && ref[len - 1] == '/')
3829                        ref[--len] = '\0';
3830                if (!hide_refs) {
3831                        hide_refs = xcalloc(1, sizeof(*hide_refs));
3832                        hide_refs->strdup_strings = 1;
3833                }
3834                string_list_append(hide_refs, ref);
3835        }
3836        return 0;
3837}
3838
3839int ref_is_hidden(const char *refname)
3840{
3841        struct string_list_item *item;
3842
3843        if (!hide_refs)
3844                return 0;
3845        for_each_string_list_item(item, hide_refs) {
3846                int len;
3847                if (!starts_with(refname, item->string))
3848                        continue;
3849                len = strlen(item->string);
3850                if (!refname[len] || refname[len] == '/')
3851                        return 1;
3852        }
3853        return 0;
3854}