4fe263ef9a5806307d4faa0641c7e7361bca4e0f
   1#include "cache.h"
   2#include "lockfile.h"
   3#include "refs.h"
   4#include "object.h"
   5#include "tag.h"
   6#include "dir.h"
   7#include "string-list.h"
   8
   9/*
  10 * How to handle various characters in refnames:
  11 * 0: An acceptable character for refs
  12 * 1: End-of-component
  13 * 2: ., look for a preceding . to reject .. in refs
  14 * 3: {, look for a preceding @ to reject @{ in refs
  15 * 4: A bad character: ASCII control characters, "~", "^", ":" or SP
  16 */
  17static unsigned char refname_disposition[256] = {
  18        1, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
  19        4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
  20        4, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4, 0, 0, 0, 2, 1,
  21        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4, 0, 0, 0, 0, 4,
  22        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  23        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4, 4, 0, 4, 0,
  24        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  25        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 3, 0, 0, 4, 4
  26};
  27
  28/*
  29 * Used as a flag to ref_transaction_delete when a loose ref is being
  30 * pruned.
  31 */
  32#define REF_ISPRUNING   0x0100
  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 ends with a "/".
  43 * - it ends with ".lock"
  44 * - it contains a "\" (backslash)
  45 */
  46static int check_refname_component(const char *refname, int flags)
  47{
  48        const char *cp;
  49        char last = '\0';
  50
  51        for (cp = refname; ; cp++) {
  52                int ch = *cp & 255;
  53                unsigned char disp = refname_disposition[ch];
  54                switch (disp) {
  55                case 1:
  56                        goto out;
  57                case 2:
  58                        if (last == '.')
  59                                return -1; /* Refname contains "..". */
  60                        break;
  61                case 3:
  62                        if (last == '@')
  63                                return -1; /* Refname contains "@{". */
  64                        break;
  65                case 4:
  66                        return -1;
  67                }
  68                last = ch;
  69        }
  70out:
  71        if (cp == refname)
  72                return 0; /* Component has zero length. */
  73        if (refname[0] == '.') {
  74                if (!(flags & REFNAME_DOT_COMPONENT))
  75                        return -1; /* Component starts with '.'. */
  76                /*
  77                 * Even if leading dots are allowed, don't allow "."
  78                 * as a component (".." is prevented by a rule above).
  79                 */
  80                if (refname[1] == '\0')
  81                        return -1; /* Component equals ".". */
  82        }
  83        if (cp - refname >= LOCK_SUFFIX_LEN &&
  84            !memcmp(cp - LOCK_SUFFIX_LEN, LOCK_SUFFIX, LOCK_SUFFIX_LEN))
  85                return -1; /* Refname ends with ".lock". */
  86        return cp - refname;
  87}
  88
  89int check_refname_format(const char *refname, int flags)
  90{
  91        int component_len, component_count = 0;
  92
  93        if (!strcmp(refname, "@"))
  94                /* Refname is a single character '@'. */
  95                return -1;
  96
  97        while (1) {
  98                /* We are at the start of a path component. */
  99                component_len = check_refname_component(refname, flags);
 100                if (component_len <= 0) {
 101                        if ((flags & REFNAME_REFSPEC_PATTERN) &&
 102                                        refname[0] == '*' &&
 103                                        (refname[1] == '\0' || refname[1] == '/')) {
 104                                /* Accept one wildcard as a full refname component. */
 105                                flags &= ~REFNAME_REFSPEC_PATTERN;
 106                                component_len = 1;
 107                        } else {
 108                                return -1;
 109                        }
 110                }
 111                component_count++;
 112                if (refname[component_len] == '\0')
 113                        break;
 114                /* Skip to next component. */
 115                refname += component_len + 1;
 116        }
 117
 118        if (refname[component_len - 1] == '.')
 119                return -1; /* Refname ends with '.'. */
 120        if (!(flags & REFNAME_ALLOW_ONELEVEL) && component_count < 2)
 121                return -1; /* Refname has only one component. */
 122        return 0;
 123}
 124
 125struct ref_entry;
 126
 127/*
 128 * Information used (along with the information in ref_entry) to
 129 * describe a single cached reference.  This data structure only
 130 * occurs embedded in a union in struct ref_entry, and only when
 131 * (ref_entry->flag & REF_DIR) is zero.
 132 */
 133struct ref_value {
 134        /*
 135         * The name of the object to which this reference resolves
 136         * (which may be a tag object).  If REF_ISBROKEN, this is
 137         * null.  If REF_ISSYMREF, then this is the name of the object
 138         * referred to by the last reference in the symlink chain.
 139         */
 140        unsigned char sha1[20];
 141
 142        /*
 143         * If REF_KNOWS_PEELED, then this field holds the peeled value
 144         * of this reference, or null if the reference is known not to
 145         * be peelable.  See the documentation for peel_ref() for an
 146         * exact definition of "peelable".
 147         */
 148        unsigned char peeled[20];
 149};
 150
 151struct ref_cache;
 152
 153/*
 154 * Information used (along with the information in ref_entry) to
 155 * describe a level in the hierarchy of references.  This data
 156 * structure only occurs embedded in a union in struct ref_entry, and
 157 * only when (ref_entry.flag & REF_DIR) is set.  In that case,
 158 * (ref_entry.flag & REF_INCOMPLETE) determines whether the references
 159 * in the directory have already been read:
 160 *
 161 *     (ref_entry.flag & REF_INCOMPLETE) unset -- a directory of loose
 162 *         or packed references, already read.
 163 *
 164 *     (ref_entry.flag & REF_INCOMPLETE) set -- a directory of loose
 165 *         references that hasn't been read yet (nor has any of its
 166 *         subdirectories).
 167 *
 168 * Entries within a directory are stored within a growable array of
 169 * pointers to ref_entries (entries, nr, alloc).  Entries 0 <= i <
 170 * sorted are sorted by their component name in strcmp() order and the
 171 * remaining entries are unsorted.
 172 *
 173 * Loose references are read lazily, one directory at a time.  When a
 174 * directory of loose references is read, then all of the references
 175 * in that directory are stored, and REF_INCOMPLETE stubs are created
 176 * for any subdirectories, but the subdirectories themselves are not
 177 * read.  The reading is triggered by get_ref_dir().
 178 */
 179struct ref_dir {
 180        int nr, alloc;
 181
 182        /*
 183         * Entries with index 0 <= i < sorted are sorted by name.  New
 184         * entries are appended to the list unsorted, and are sorted
 185         * only when required; thus we avoid the need to sort the list
 186         * after the addition of every reference.
 187         */
 188        int sorted;
 189
 190        /* A pointer to the ref_cache that contains this ref_dir. */
 191        struct ref_cache *ref_cache;
 192
 193        struct ref_entry **entries;
 194};
 195
 196/*
 197 * Bit values for ref_entry::flag.  REF_ISSYMREF=0x01,
 198 * REF_ISPACKED=0x02, and REF_ISBROKEN=0x04 are public values; see
 199 * refs.h.
 200 */
 201
 202/*
 203 * The field ref_entry->u.value.peeled of this value entry contains
 204 * the correct peeled value for the reference, which might be
 205 * null_sha1 if the reference is not a tag or if it is broken.
 206 */
 207#define REF_KNOWS_PEELED 0x08
 208
 209/* ref_entry represents a directory of references */
 210#define REF_DIR 0x10
 211
 212/*
 213 * Entry has not yet been read from disk (used only for REF_DIR
 214 * entries representing loose references)
 215 */
 216#define REF_INCOMPLETE 0x20
 217
 218/*
 219 * A ref_entry represents either a reference or a "subdirectory" of
 220 * references.
 221 *
 222 * Each directory in the reference namespace is represented by a
 223 * ref_entry with (flags & REF_DIR) set and containing a subdir member
 224 * that holds the entries in that directory that have been read so
 225 * far.  If (flags & REF_INCOMPLETE) is set, then the directory and
 226 * its subdirectories haven't been read yet.  REF_INCOMPLETE is only
 227 * used for loose reference directories.
 228 *
 229 * References are represented by a ref_entry with (flags & REF_DIR)
 230 * unset and a value member that describes the reference's value.  The
 231 * flag member is at the ref_entry level, but it is also needed to
 232 * interpret the contents of the value field (in other words, a
 233 * ref_value object is not very much use without the enclosing
 234 * ref_entry).
 235 *
 236 * Reference names cannot end with slash and directories' names are
 237 * always stored with a trailing slash (except for the top-level
 238 * directory, which is always denoted by "").  This has two nice
 239 * consequences: (1) when the entries in each subdir are sorted
 240 * lexicographically by name (as they usually are), the references in
 241 * a whole tree can be generated in lexicographic order by traversing
 242 * the tree in left-to-right, depth-first order; (2) the names of
 243 * references and subdirectories cannot conflict, and therefore the
 244 * presence of an empty subdirectory does not block the creation of a
 245 * similarly-named reference.  (The fact that reference names with the
 246 * same leading components can conflict *with each other* is a
 247 * separate issue that is regulated by is_refname_available().)
 248 *
 249 * Please note that the name field contains the fully-qualified
 250 * reference (or subdirectory) name.  Space could be saved by only
 251 * storing the relative names.  But that would require the full names
 252 * to be generated on the fly when iterating in do_for_each_ref(), and
 253 * would break callback functions, who have always been able to assume
 254 * that the name strings that they are passed will not be freed during
 255 * the iteration.
 256 */
 257struct ref_entry {
 258        unsigned char flag; /* ISSYMREF? ISPACKED? */
 259        union {
 260                struct ref_value value; /* if not (flags&REF_DIR) */
 261                struct ref_dir subdir; /* if (flags&REF_DIR) */
 262        } u;
 263        /*
 264         * The full name of the reference (e.g., "refs/heads/master")
 265         * or the full name of the directory with a trailing slash
 266         * (e.g., "refs/heads/"):
 267         */
 268        char name[FLEX_ARRAY];
 269};
 270
 271static void read_loose_refs(const char *dirname, struct ref_dir *dir);
 272
 273static struct ref_dir *get_ref_dir(struct ref_entry *entry)
 274{
 275        struct ref_dir *dir;
 276        assert(entry->flag & REF_DIR);
 277        dir = &entry->u.subdir;
 278        if (entry->flag & REF_INCOMPLETE) {
 279                read_loose_refs(entry->name, dir);
 280                entry->flag &= ~REF_INCOMPLETE;
 281        }
 282        return dir;
 283}
 284
 285static struct ref_entry *create_ref_entry(const char *refname,
 286                                          const unsigned char *sha1, int flag,
 287                                          int check_name)
 288{
 289        int len;
 290        struct ref_entry *ref;
 291
 292        if (check_name &&
 293            check_refname_format(refname, REFNAME_ALLOW_ONELEVEL|REFNAME_DOT_COMPONENT))
 294                die("Reference has invalid format: '%s'", refname);
 295        len = strlen(refname) + 1;
 296        ref = xmalloc(sizeof(struct ref_entry) + len);
 297        hashcpy(ref->u.value.sha1, sha1);
 298        hashclr(ref->u.value.peeled);
 299        memcpy(ref->name, refname, len);
 300        ref->flag = flag;
 301        return ref;
 302}
 303
 304static void clear_ref_dir(struct ref_dir *dir);
 305
 306static void free_ref_entry(struct ref_entry *entry)
 307{
 308        if (entry->flag & REF_DIR) {
 309                /*
 310                 * Do not use get_ref_dir() here, as that might
 311                 * trigger the reading of loose refs.
 312                 */
 313                clear_ref_dir(&entry->u.subdir);
 314        }
 315        free(entry);
 316}
 317
 318/*
 319 * Add a ref_entry to the end of dir (unsorted).  Entry is always
 320 * stored directly in dir; no recursion into subdirectories is
 321 * done.
 322 */
 323static void add_entry_to_dir(struct ref_dir *dir, struct ref_entry *entry)
 324{
 325        ALLOC_GROW(dir->entries, dir->nr + 1, dir->alloc);
 326        dir->entries[dir->nr++] = entry;
 327        /* optimize for the case that entries are added in order */
 328        if (dir->nr == 1 ||
 329            (dir->nr == dir->sorted + 1 &&
 330             strcmp(dir->entries[dir->nr - 2]->name,
 331                    dir->entries[dir->nr - 1]->name) < 0))
 332                dir->sorted = dir->nr;
 333}
 334
 335/*
 336 * Clear and free all entries in dir, recursively.
 337 */
 338static void clear_ref_dir(struct ref_dir *dir)
 339{
 340        int i;
 341        for (i = 0; i < dir->nr; i++)
 342                free_ref_entry(dir->entries[i]);
 343        free(dir->entries);
 344        dir->sorted = dir->nr = dir->alloc = 0;
 345        dir->entries = NULL;
 346}
 347
 348/*
 349 * Create a struct ref_entry object for the specified dirname.
 350 * dirname is the name of the directory with a trailing slash (e.g.,
 351 * "refs/heads/") or "" for the top-level directory.
 352 */
 353static struct ref_entry *create_dir_entry(struct ref_cache *ref_cache,
 354                                          const char *dirname, size_t len,
 355                                          int incomplete)
 356{
 357        struct ref_entry *direntry;
 358        direntry = xcalloc(1, sizeof(struct ref_entry) + len + 1);
 359        memcpy(direntry->name, dirname, len);
 360        direntry->name[len] = '\0';
 361        direntry->u.subdir.ref_cache = ref_cache;
 362        direntry->flag = REF_DIR | (incomplete ? REF_INCOMPLETE : 0);
 363        return direntry;
 364}
 365
 366static int ref_entry_cmp(const void *a, const void *b)
 367{
 368        struct ref_entry *one = *(struct ref_entry **)a;
 369        struct ref_entry *two = *(struct ref_entry **)b;
 370        return strcmp(one->name, two->name);
 371}
 372
 373static void sort_ref_dir(struct ref_dir *dir);
 374
 375struct string_slice {
 376        size_t len;
 377        const char *str;
 378};
 379
 380static int ref_entry_cmp_sslice(const void *key_, const void *ent_)
 381{
 382        const struct string_slice *key = key_;
 383        const struct ref_entry *ent = *(const struct ref_entry * const *)ent_;
 384        int cmp = strncmp(key->str, ent->name, key->len);
 385        if (cmp)
 386                return cmp;
 387        return '\0' - (unsigned char)ent->name[key->len];
 388}
 389
 390/*
 391 * Return the index of the entry with the given refname from the
 392 * ref_dir (non-recursively), sorting dir if necessary.  Return -1 if
 393 * no such entry is found.  dir must already be complete.
 394 */
 395static int search_ref_dir(struct ref_dir *dir, const char *refname, size_t len)
 396{
 397        struct ref_entry **r;
 398        struct string_slice key;
 399
 400        if (refname == NULL || !dir->nr)
 401                return -1;
 402
 403        sort_ref_dir(dir);
 404        key.len = len;
 405        key.str = refname;
 406        r = bsearch(&key, dir->entries, dir->nr, sizeof(*dir->entries),
 407                    ref_entry_cmp_sslice);
 408
 409        if (r == NULL)
 410                return -1;
 411
 412        return r - dir->entries;
 413}
 414
 415/*
 416 * Search for a directory entry directly within dir (without
 417 * recursing).  Sort dir if necessary.  subdirname must be a directory
 418 * name (i.e., end in '/').  If mkdir is set, then create the
 419 * directory if it is missing; otherwise, return NULL if the desired
 420 * directory cannot be found.  dir must already be complete.
 421 */
 422static struct ref_dir *search_for_subdir(struct ref_dir *dir,
 423                                         const char *subdirname, size_t len,
 424                                         int mkdir)
 425{
 426        int entry_index = search_ref_dir(dir, subdirname, len);
 427        struct ref_entry *entry;
 428        if (entry_index == -1) {
 429                if (!mkdir)
 430                        return NULL;
 431                /*
 432                 * Since dir is complete, the absence of a subdir
 433                 * means that the subdir really doesn't exist;
 434                 * therefore, create an empty record for it but mark
 435                 * the record complete.
 436                 */
 437                entry = create_dir_entry(dir->ref_cache, subdirname, len, 0);
 438                add_entry_to_dir(dir, entry);
 439        } else {
 440                entry = dir->entries[entry_index];
 441        }
 442        return get_ref_dir(entry);
 443}
 444
 445/*
 446 * If refname is a reference name, find the ref_dir within the dir
 447 * tree that should hold refname.  If refname is a directory name
 448 * (i.e., ends in '/'), then return that ref_dir itself.  dir must
 449 * represent the top-level directory and must already be complete.
 450 * Sort ref_dirs and recurse into subdirectories as necessary.  If
 451 * mkdir is set, then create any missing directories; otherwise,
 452 * return NULL if the desired directory cannot be found.
 453 */
 454static struct ref_dir *find_containing_dir(struct ref_dir *dir,
 455                                           const char *refname, int mkdir)
 456{
 457        const char *slash;
 458        for (slash = strchr(refname, '/'); slash; slash = strchr(slash + 1, '/')) {
 459                size_t dirnamelen = slash - refname + 1;
 460                struct ref_dir *subdir;
 461                subdir = search_for_subdir(dir, refname, dirnamelen, mkdir);
 462                if (!subdir) {
 463                        dir = NULL;
 464                        break;
 465                }
 466                dir = subdir;
 467        }
 468
 469        return dir;
 470}
 471
 472/*
 473 * Find the value entry with the given name in dir, sorting ref_dirs
 474 * and recursing into subdirectories as necessary.  If the name is not
 475 * found or it corresponds to a directory entry, return NULL.
 476 */
 477static struct ref_entry *find_ref(struct ref_dir *dir, const char *refname)
 478{
 479        int entry_index;
 480        struct ref_entry *entry;
 481        dir = find_containing_dir(dir, refname, 0);
 482        if (!dir)
 483                return NULL;
 484        entry_index = search_ref_dir(dir, refname, strlen(refname));
 485        if (entry_index == -1)
 486                return NULL;
 487        entry = dir->entries[entry_index];
 488        return (entry->flag & REF_DIR) ? NULL : entry;
 489}
 490
 491/*
 492 * Remove the entry with the given name from dir, recursing into
 493 * subdirectories as necessary.  If refname is the name of a directory
 494 * (i.e., ends with '/'), then remove the directory and its contents.
 495 * If the removal was successful, return the number of entries
 496 * remaining in the directory entry that contained the deleted entry.
 497 * If the name was not found, return -1.  Please note that this
 498 * function only deletes the entry from the cache; it does not delete
 499 * it from the filesystem or ensure that other cache entries (which
 500 * might be symbolic references to the removed entry) are updated.
 501 * Nor does it remove any containing dir entries that might be made
 502 * empty by the removal.  dir must represent the top-level directory
 503 * and must already be complete.
 504 */
 505static int remove_entry(struct ref_dir *dir, const char *refname)
 506{
 507        int refname_len = strlen(refname);
 508        int entry_index;
 509        struct ref_entry *entry;
 510        int is_dir = refname[refname_len - 1] == '/';
 511        if (is_dir) {
 512                /*
 513                 * refname represents a reference directory.  Remove
 514                 * the trailing slash; otherwise we will get the
 515                 * directory *representing* refname rather than the
 516                 * one *containing* it.
 517                 */
 518                char *dirname = xmemdupz(refname, refname_len - 1);
 519                dir = find_containing_dir(dir, dirname, 0);
 520                free(dirname);
 521        } else {
 522                dir = find_containing_dir(dir, refname, 0);
 523        }
 524        if (!dir)
 525                return -1;
 526        entry_index = search_ref_dir(dir, refname, refname_len);
 527        if (entry_index == -1)
 528                return -1;
 529        entry = dir->entries[entry_index];
 530
 531        memmove(&dir->entries[entry_index],
 532                &dir->entries[entry_index + 1],
 533                (dir->nr - entry_index - 1) * sizeof(*dir->entries)
 534                );
 535        dir->nr--;
 536        if (dir->sorted > entry_index)
 537                dir->sorted--;
 538        free_ref_entry(entry);
 539        return dir->nr;
 540}
 541
 542/*
 543 * Add a ref_entry to the ref_dir (unsorted), recursing into
 544 * subdirectories as necessary.  dir must represent the top-level
 545 * directory.  Return 0 on success.
 546 */
 547static int add_ref(struct ref_dir *dir, struct ref_entry *ref)
 548{
 549        dir = find_containing_dir(dir, ref->name, 1);
 550        if (!dir)
 551                return -1;
 552        add_entry_to_dir(dir, ref);
 553        return 0;
 554}
 555
 556/*
 557 * Emit a warning and return true iff ref1 and ref2 have the same name
 558 * and the same sha1.  Die if they have the same name but different
 559 * sha1s.
 560 */
 561static int is_dup_ref(const struct ref_entry *ref1, const struct ref_entry *ref2)
 562{
 563        if (strcmp(ref1->name, ref2->name))
 564                return 0;
 565
 566        /* Duplicate name; make sure that they don't conflict: */
 567
 568        if ((ref1->flag & REF_DIR) || (ref2->flag & REF_DIR))
 569                /* This is impossible by construction */
 570                die("Reference directory conflict: %s", ref1->name);
 571
 572        if (hashcmp(ref1->u.value.sha1, ref2->u.value.sha1))
 573                die("Duplicated ref, and SHA1s don't match: %s", ref1->name);
 574
 575        warning("Duplicated ref: %s", ref1->name);
 576        return 1;
 577}
 578
 579/*
 580 * Sort the entries in dir non-recursively (if they are not already
 581 * sorted) and remove any duplicate entries.
 582 */
 583static void sort_ref_dir(struct ref_dir *dir)
 584{
 585        int i, j;
 586        struct ref_entry *last = NULL;
 587
 588        /*
 589         * This check also prevents passing a zero-length array to qsort(),
 590         * which is a problem on some platforms.
 591         */
 592        if (dir->sorted == dir->nr)
 593                return;
 594
 595        qsort(dir->entries, dir->nr, sizeof(*dir->entries), ref_entry_cmp);
 596
 597        /* Remove any duplicates: */
 598        for (i = 0, j = 0; j < dir->nr; j++) {
 599                struct ref_entry *entry = dir->entries[j];
 600                if (last && is_dup_ref(last, entry))
 601                        free_ref_entry(entry);
 602                else
 603                        last = dir->entries[i++] = entry;
 604        }
 605        dir->sorted = dir->nr = i;
 606}
 607
 608/* Include broken references in a do_for_each_ref*() iteration: */
 609#define DO_FOR_EACH_INCLUDE_BROKEN 0x01
 610
 611/*
 612 * Return true iff the reference described by entry can be resolved to
 613 * an object in the database.  Emit a warning if the referred-to
 614 * object does not exist.
 615 */
 616static int ref_resolves_to_object(struct ref_entry *entry)
 617{
 618        if (entry->flag & REF_ISBROKEN)
 619                return 0;
 620        if (!has_sha1_file(entry->u.value.sha1)) {
 621                error("%s does not point to a valid object!", entry->name);
 622                return 0;
 623        }
 624        return 1;
 625}
 626
 627/*
 628 * current_ref is a performance hack: when iterating over references
 629 * using the for_each_ref*() functions, current_ref is set to the
 630 * current reference's entry before calling the callback function.  If
 631 * the callback function calls peel_ref(), then peel_ref() first
 632 * checks whether the reference to be peeled is the current reference
 633 * (it usually is) and if so, returns that reference's peeled version
 634 * if it is available.  This avoids a refname lookup in a common case.
 635 */
 636static struct ref_entry *current_ref;
 637
 638typedef int each_ref_entry_fn(struct ref_entry *entry, void *cb_data);
 639
 640struct ref_entry_cb {
 641        const char *base;
 642        int trim;
 643        int flags;
 644        each_ref_fn *fn;
 645        void *cb_data;
 646};
 647
 648/*
 649 * Handle one reference in a do_for_each_ref*()-style iteration,
 650 * calling an each_ref_fn for each entry.
 651 */
 652static int do_one_ref(struct ref_entry *entry, void *cb_data)
 653{
 654        struct ref_entry_cb *data = cb_data;
 655        struct ref_entry *old_current_ref;
 656        int retval;
 657
 658        if (!starts_with(entry->name, data->base))
 659                return 0;
 660
 661        if (!(data->flags & DO_FOR_EACH_INCLUDE_BROKEN) &&
 662              !ref_resolves_to_object(entry))
 663                return 0;
 664
 665        /* Store the old value, in case this is a recursive call: */
 666        old_current_ref = current_ref;
 667        current_ref = entry;
 668        retval = data->fn(entry->name + data->trim, entry->u.value.sha1,
 669                          entry->flag, data->cb_data);
 670        current_ref = old_current_ref;
 671        return retval;
 672}
 673
 674/*
 675 * Call fn for each reference in dir that has index in the range
 676 * offset <= index < dir->nr.  Recurse into subdirectories that are in
 677 * that index range, sorting them before iterating.  This function
 678 * does not sort dir itself; it should be sorted beforehand.  fn is
 679 * called for all references, including broken ones.
 680 */
 681static int do_for_each_entry_in_dir(struct ref_dir *dir, int offset,
 682                                    each_ref_entry_fn fn, void *cb_data)
 683{
 684        int i;
 685        assert(dir->sorted == dir->nr);
 686        for (i = offset; i < dir->nr; i++) {
 687                struct ref_entry *entry = dir->entries[i];
 688                int retval;
 689                if (entry->flag & REF_DIR) {
 690                        struct ref_dir *subdir = get_ref_dir(entry);
 691                        sort_ref_dir(subdir);
 692                        retval = do_for_each_entry_in_dir(subdir, 0, fn, cb_data);
 693                } else {
 694                        retval = fn(entry, cb_data);
 695                }
 696                if (retval)
 697                        return retval;
 698        }
 699        return 0;
 700}
 701
 702/*
 703 * Call fn for each reference in the union of dir1 and dir2, in order
 704 * by refname.  Recurse into subdirectories.  If a value entry appears
 705 * in both dir1 and dir2, then only process the version that is in
 706 * dir2.  The input dirs must already be sorted, but subdirs will be
 707 * sorted as needed.  fn is called for all references, including
 708 * broken ones.
 709 */
 710static int do_for_each_entry_in_dirs(struct ref_dir *dir1,
 711                                     struct ref_dir *dir2,
 712                                     each_ref_entry_fn fn, void *cb_data)
 713{
 714        int retval;
 715        int i1 = 0, i2 = 0;
 716
 717        assert(dir1->sorted == dir1->nr);
 718        assert(dir2->sorted == dir2->nr);
 719        while (1) {
 720                struct ref_entry *e1, *e2;
 721                int cmp;
 722                if (i1 == dir1->nr) {
 723                        return do_for_each_entry_in_dir(dir2, i2, fn, cb_data);
 724                }
 725                if (i2 == dir2->nr) {
 726                        return do_for_each_entry_in_dir(dir1, i1, fn, cb_data);
 727                }
 728                e1 = dir1->entries[i1];
 729                e2 = dir2->entries[i2];
 730                cmp = strcmp(e1->name, e2->name);
 731                if (cmp == 0) {
 732                        if ((e1->flag & REF_DIR) && (e2->flag & REF_DIR)) {
 733                                /* Both are directories; descend them in parallel. */
 734                                struct ref_dir *subdir1 = get_ref_dir(e1);
 735                                struct ref_dir *subdir2 = get_ref_dir(e2);
 736                                sort_ref_dir(subdir1);
 737                                sort_ref_dir(subdir2);
 738                                retval = do_for_each_entry_in_dirs(
 739                                                subdir1, subdir2, fn, cb_data);
 740                                i1++;
 741                                i2++;
 742                        } else if (!(e1->flag & REF_DIR) && !(e2->flag & REF_DIR)) {
 743                                /* Both are references; ignore the one from dir1. */
 744                                retval = fn(e2, cb_data);
 745                                i1++;
 746                                i2++;
 747                        } else {
 748                                die("conflict between reference and directory: %s",
 749                                    e1->name);
 750                        }
 751                } else {
 752                        struct ref_entry *e;
 753                        if (cmp < 0) {
 754                                e = e1;
 755                                i1++;
 756                        } else {
 757                                e = e2;
 758                                i2++;
 759                        }
 760                        if (e->flag & REF_DIR) {
 761                                struct ref_dir *subdir = get_ref_dir(e);
 762                                sort_ref_dir(subdir);
 763                                retval = do_for_each_entry_in_dir(
 764                                                subdir, 0, fn, cb_data);
 765                        } else {
 766                                retval = fn(e, cb_data);
 767                        }
 768                }
 769                if (retval)
 770                        return retval;
 771        }
 772}
 773
 774/*
 775 * Load all of the refs from the dir into our in-memory cache. The hard work
 776 * of loading loose refs is done by get_ref_dir(), so we just need to recurse
 777 * through all of the sub-directories. We do not even need to care about
 778 * sorting, as traversal order does not matter to us.
 779 */
 780static void prime_ref_dir(struct ref_dir *dir)
 781{
 782        int i;
 783        for (i = 0; i < dir->nr; i++) {
 784                struct ref_entry *entry = dir->entries[i];
 785                if (entry->flag & REF_DIR)
 786                        prime_ref_dir(get_ref_dir(entry));
 787        }
 788}
 789
 790static int entry_matches(struct ref_entry *entry, const struct string_list *list)
 791{
 792        return list && string_list_has_string(list, entry->name);
 793}
 794
 795struct nonmatching_ref_data {
 796        const struct string_list *skip;
 797        struct ref_entry *found;
 798};
 799
 800static int nonmatching_ref_fn(struct ref_entry *entry, void *vdata)
 801{
 802        struct nonmatching_ref_data *data = vdata;
 803
 804        if (entry_matches(entry, data->skip))
 805                return 0;
 806
 807        data->found = entry;
 808        return 1;
 809}
 810
 811static void report_refname_conflict(struct ref_entry *entry,
 812                                    const char *refname)
 813{
 814        error("'%s' exists; cannot create '%s'", entry->name, refname);
 815}
 816
 817/*
 818 * Return true iff a reference named refname could be created without
 819 * conflicting with the name of an existing reference in dir.  If
 820 * skip is non-NULL, ignore potential conflicts with refs in skip
 821 * (e.g., because they are scheduled for deletion in the same
 822 * operation).
 823 *
 824 * Two reference names conflict if one of them exactly matches the
 825 * leading components of the other; e.g., "foo/bar" conflicts with
 826 * both "foo" and with "foo/bar/baz" but not with "foo/bar" or
 827 * "foo/barbados".
 828 *
 829 * skip must be sorted.
 830 */
 831static int is_refname_available(const char *refname,
 832                                const struct string_list *skip,
 833                                struct ref_dir *dir)
 834{
 835        const char *slash;
 836        size_t len;
 837        int pos;
 838        char *dirname;
 839
 840        for (slash = strchr(refname, '/'); slash; slash = strchr(slash + 1, '/')) {
 841                /*
 842                 * We are still at a leading dir of the refname; we are
 843                 * looking for a conflict with a leaf entry.
 844                 *
 845                 * If we find one, we still must make sure it is
 846                 * not in "skip".
 847                 */
 848                pos = search_ref_dir(dir, refname, slash - refname);
 849                if (pos >= 0) {
 850                        struct ref_entry *entry = dir->entries[pos];
 851                        if (entry_matches(entry, skip))
 852                                return 1;
 853                        report_refname_conflict(entry, refname);
 854                        return 0;
 855                }
 856
 857
 858                /*
 859                 * Otherwise, we can try to continue our search with
 860                 * the next component; if we come up empty, we know
 861                 * there is nothing under this whole prefix.
 862                 */
 863                pos = search_ref_dir(dir, refname, slash + 1 - refname);
 864                if (pos < 0)
 865                        return 1;
 866
 867                dir = get_ref_dir(dir->entries[pos]);
 868        }
 869
 870        /*
 871         * We are at the leaf of our refname; we want to
 872         * make sure there are no directories which match it.
 873         */
 874        len = strlen(refname);
 875        dirname = xmallocz(len + 1);
 876        sprintf(dirname, "%s/", refname);
 877        pos = search_ref_dir(dir, dirname, len + 1);
 878        free(dirname);
 879
 880        if (pos >= 0) {
 881                /*
 882                 * We found a directory named "refname". It is a
 883                 * problem iff it contains any ref that is not
 884                 * in "skip".
 885                 */
 886                struct ref_entry *entry = dir->entries[pos];
 887                struct ref_dir *dir = get_ref_dir(entry);
 888                struct nonmatching_ref_data data;
 889
 890                data.skip = skip;
 891                sort_ref_dir(dir);
 892                if (!do_for_each_entry_in_dir(dir, 0, nonmatching_ref_fn, &data))
 893                        return 1;
 894
 895                report_refname_conflict(data.found, refname);
 896                return 0;
 897        }
 898
 899        /*
 900         * There is no point in searching for another leaf
 901         * node which matches it; such an entry would be the
 902         * ref we are looking for, not a conflict.
 903         */
 904        return 1;
 905}
 906
 907struct packed_ref_cache {
 908        struct ref_entry *root;
 909
 910        /*
 911         * Count of references to the data structure in this instance,
 912         * including the pointer from ref_cache::packed if any.  The
 913         * data will not be freed as long as the reference count is
 914         * nonzero.
 915         */
 916        unsigned int referrers;
 917
 918        /*
 919         * Iff the packed-refs file associated with this instance is
 920         * currently locked for writing, this points at the associated
 921         * lock (which is owned by somebody else).  The referrer count
 922         * is also incremented when the file is locked and decremented
 923         * when it is unlocked.
 924         */
 925        struct lock_file *lock;
 926
 927        /* The metadata from when this packed-refs cache was read */
 928        struct stat_validity validity;
 929};
 930
 931/*
 932 * Future: need to be in "struct repository"
 933 * when doing a full libification.
 934 */
 935static struct ref_cache {
 936        struct ref_cache *next;
 937        struct ref_entry *loose;
 938        struct packed_ref_cache *packed;
 939        /*
 940         * The submodule name, or "" for the main repo.  We allocate
 941         * length 1 rather than FLEX_ARRAY so that the main ref_cache
 942         * is initialized correctly.
 943         */
 944        char name[1];
 945} ref_cache, *submodule_ref_caches;
 946
 947/* Lock used for the main packed-refs file: */
 948static struct lock_file packlock;
 949
 950/*
 951 * Increment the reference count of *packed_refs.
 952 */
 953static void acquire_packed_ref_cache(struct packed_ref_cache *packed_refs)
 954{
 955        packed_refs->referrers++;
 956}
 957
 958/*
 959 * Decrease the reference count of *packed_refs.  If it goes to zero,
 960 * free *packed_refs and return true; otherwise return false.
 961 */
 962static int release_packed_ref_cache(struct packed_ref_cache *packed_refs)
 963{
 964        if (!--packed_refs->referrers) {
 965                free_ref_entry(packed_refs->root);
 966                stat_validity_clear(&packed_refs->validity);
 967                free(packed_refs);
 968                return 1;
 969        } else {
 970                return 0;
 971        }
 972}
 973
 974static void clear_packed_ref_cache(struct ref_cache *refs)
 975{
 976        if (refs->packed) {
 977                struct packed_ref_cache *packed_refs = refs->packed;
 978
 979                if (packed_refs->lock)
 980                        die("internal error: packed-ref cache cleared while locked");
 981                refs->packed = NULL;
 982                release_packed_ref_cache(packed_refs);
 983        }
 984}
 985
 986static void clear_loose_ref_cache(struct ref_cache *refs)
 987{
 988        if (refs->loose) {
 989                free_ref_entry(refs->loose);
 990                refs->loose = NULL;
 991        }
 992}
 993
 994static struct ref_cache *create_ref_cache(const char *submodule)
 995{
 996        int len;
 997        struct ref_cache *refs;
 998        if (!submodule)
 999                submodule = "";
1000        len = strlen(submodule) + 1;
1001        refs = xcalloc(1, sizeof(struct ref_cache) + len);
1002        memcpy(refs->name, submodule, len);
1003        return refs;
1004}
1005
1006/*
1007 * Return a pointer to a ref_cache for the specified submodule. For
1008 * the main repository, use submodule==NULL. The returned structure
1009 * will be allocated and initialized but not necessarily populated; it
1010 * should not be freed.
1011 */
1012static struct ref_cache *get_ref_cache(const char *submodule)
1013{
1014        struct ref_cache *refs;
1015
1016        if (!submodule || !*submodule)
1017                return &ref_cache;
1018
1019        for (refs = submodule_ref_caches; refs; refs = refs->next)
1020                if (!strcmp(submodule, refs->name))
1021                        return refs;
1022
1023        refs = create_ref_cache(submodule);
1024        refs->next = submodule_ref_caches;
1025        submodule_ref_caches = refs;
1026        return refs;
1027}
1028
1029/* The length of a peeled reference line in packed-refs, including EOL: */
1030#define PEELED_LINE_LENGTH 42
1031
1032/*
1033 * The packed-refs header line that we write out.  Perhaps other
1034 * traits will be added later.  The trailing space is required.
1035 */
1036static const char PACKED_REFS_HEADER[] =
1037        "# pack-refs with: peeled fully-peeled \n";
1038
1039/*
1040 * Parse one line from a packed-refs file.  Write the SHA1 to sha1.
1041 * Return a pointer to the refname within the line (null-terminated),
1042 * or NULL if there was a problem.
1043 */
1044static const char *parse_ref_line(char *line, unsigned char *sha1)
1045{
1046        /*
1047         * 42: the answer to everything.
1048         *
1049         * In this case, it happens to be the answer to
1050         *  40 (length of sha1 hex representation)
1051         *  +1 (space in between hex and name)
1052         *  +1 (newline at the end of the line)
1053         */
1054        int len = strlen(line) - 42;
1055
1056        if (len <= 0)
1057                return NULL;
1058        if (get_sha1_hex(line, sha1) < 0)
1059                return NULL;
1060        if (!isspace(line[40]))
1061                return NULL;
1062        line += 41;
1063        if (isspace(*line))
1064                return NULL;
1065        if (line[len] != '\n')
1066                return NULL;
1067        line[len] = 0;
1068
1069        return line;
1070}
1071
1072/*
1073 * Read f, which is a packed-refs file, into dir.
1074 *
1075 * A comment line of the form "# pack-refs with: " may contain zero or
1076 * more traits. We interpret the traits as follows:
1077 *
1078 *   No traits:
1079 *
1080 *      Probably no references are peeled. But if the file contains a
1081 *      peeled value for a reference, we will use it.
1082 *
1083 *   peeled:
1084 *
1085 *      References under "refs/tags/", if they *can* be peeled, *are*
1086 *      peeled in this file. References outside of "refs/tags/" are
1087 *      probably not peeled even if they could have been, but if we find
1088 *      a peeled value for such a reference we will use it.
1089 *
1090 *   fully-peeled:
1091 *
1092 *      All references in the file that can be peeled are peeled.
1093 *      Inversely (and this is more important), any references in the
1094 *      file for which no peeled value is recorded is not peelable. This
1095 *      trait should typically be written alongside "peeled" for
1096 *      compatibility with older clients, but we do not require it
1097 *      (i.e., "peeled" is a no-op if "fully-peeled" is set).
1098 */
1099static void read_packed_refs(FILE *f, struct ref_dir *dir)
1100{
1101        struct ref_entry *last = NULL;
1102        char refline[PATH_MAX];
1103        enum { PEELED_NONE, PEELED_TAGS, PEELED_FULLY } peeled = PEELED_NONE;
1104
1105        while (fgets(refline, sizeof(refline), f)) {
1106                unsigned char sha1[20];
1107                const char *refname;
1108                static const char header[] = "# pack-refs with:";
1109
1110                if (!strncmp(refline, header, sizeof(header)-1)) {
1111                        const char *traits = refline + sizeof(header) - 1;
1112                        if (strstr(traits, " fully-peeled "))
1113                                peeled = PEELED_FULLY;
1114                        else if (strstr(traits, " peeled "))
1115                                peeled = PEELED_TAGS;
1116                        /* perhaps other traits later as well */
1117                        continue;
1118                }
1119
1120                refname = parse_ref_line(refline, sha1);
1121                if (refname) {
1122                        last = create_ref_entry(refname, sha1, REF_ISPACKED, 1);
1123                        if (peeled == PEELED_FULLY ||
1124                            (peeled == PEELED_TAGS && starts_with(refname, "refs/tags/")))
1125                                last->flag |= REF_KNOWS_PEELED;
1126                        add_ref(dir, last);
1127                        continue;
1128                }
1129                if (last &&
1130                    refline[0] == '^' &&
1131                    strlen(refline) == PEELED_LINE_LENGTH &&
1132                    refline[PEELED_LINE_LENGTH - 1] == '\n' &&
1133                    !get_sha1_hex(refline + 1, sha1)) {
1134                        hashcpy(last->u.value.peeled, sha1);
1135                        /*
1136                         * Regardless of what the file header said,
1137                         * we definitely know the value of *this*
1138                         * reference:
1139                         */
1140                        last->flag |= REF_KNOWS_PEELED;
1141                }
1142        }
1143}
1144
1145/*
1146 * Get the packed_ref_cache for the specified ref_cache, creating it
1147 * if necessary.
1148 */
1149static struct packed_ref_cache *get_packed_ref_cache(struct ref_cache *refs)
1150{
1151        const char *packed_refs_file;
1152
1153        if (*refs->name)
1154                packed_refs_file = git_path_submodule(refs->name, "packed-refs");
1155        else
1156                packed_refs_file = git_path("packed-refs");
1157
1158        if (refs->packed &&
1159            !stat_validity_check(&refs->packed->validity, packed_refs_file))
1160                clear_packed_ref_cache(refs);
1161
1162        if (!refs->packed) {
1163                FILE *f;
1164
1165                refs->packed = xcalloc(1, sizeof(*refs->packed));
1166                acquire_packed_ref_cache(refs->packed);
1167                refs->packed->root = create_dir_entry(refs, "", 0, 0);
1168                f = fopen(packed_refs_file, "r");
1169                if (f) {
1170                        stat_validity_update(&refs->packed->validity, fileno(f));
1171                        read_packed_refs(f, get_ref_dir(refs->packed->root));
1172                        fclose(f);
1173                }
1174        }
1175        return refs->packed;
1176}
1177
1178static struct ref_dir *get_packed_ref_dir(struct packed_ref_cache *packed_ref_cache)
1179{
1180        return get_ref_dir(packed_ref_cache->root);
1181}
1182
1183static struct ref_dir *get_packed_refs(struct ref_cache *refs)
1184{
1185        return get_packed_ref_dir(get_packed_ref_cache(refs));
1186}
1187
1188void add_packed_ref(const char *refname, const unsigned char *sha1)
1189{
1190        struct packed_ref_cache *packed_ref_cache =
1191                get_packed_ref_cache(&ref_cache);
1192
1193        if (!packed_ref_cache->lock)
1194                die("internal error: packed refs not locked");
1195        add_ref(get_packed_ref_dir(packed_ref_cache),
1196                create_ref_entry(refname, sha1, REF_ISPACKED, 1));
1197}
1198
1199/*
1200 * Read the loose references from the namespace dirname into dir
1201 * (without recursing).  dirname must end with '/'.  dir must be the
1202 * directory entry corresponding to dirname.
1203 */
1204static void read_loose_refs(const char *dirname, struct ref_dir *dir)
1205{
1206        struct ref_cache *refs = dir->ref_cache;
1207        DIR *d;
1208        const char *path;
1209        struct dirent *de;
1210        int dirnamelen = strlen(dirname);
1211        struct strbuf refname;
1212
1213        if (*refs->name)
1214                path = git_path_submodule(refs->name, "%s", dirname);
1215        else
1216                path = git_path("%s", dirname);
1217
1218        d = opendir(path);
1219        if (!d)
1220                return;
1221
1222        strbuf_init(&refname, dirnamelen + 257);
1223        strbuf_add(&refname, dirname, dirnamelen);
1224
1225        while ((de = readdir(d)) != NULL) {
1226                unsigned char sha1[20];
1227                struct stat st;
1228                int flag;
1229                const char *refdir;
1230
1231                if (de->d_name[0] == '.')
1232                        continue;
1233                if (ends_with(de->d_name, ".lock"))
1234                        continue;
1235                strbuf_addstr(&refname, de->d_name);
1236                refdir = *refs->name
1237                        ? git_path_submodule(refs->name, "%s", refname.buf)
1238                        : git_path("%s", refname.buf);
1239                if (stat(refdir, &st) < 0) {
1240                        ; /* silently ignore */
1241                } else if (S_ISDIR(st.st_mode)) {
1242                        strbuf_addch(&refname, '/');
1243                        add_entry_to_dir(dir,
1244                                         create_dir_entry(refs, refname.buf,
1245                                                          refname.len, 1));
1246                } else {
1247                        if (*refs->name) {
1248                                hashclr(sha1);
1249                                flag = 0;
1250                                if (resolve_gitlink_ref(refs->name, refname.buf, sha1) < 0) {
1251                                        hashclr(sha1);
1252                                        flag |= REF_ISBROKEN;
1253                                }
1254                        } else if (read_ref_full(refname.buf,
1255                                                 RESOLVE_REF_READING,
1256                                                 sha1, &flag)) {
1257                                hashclr(sha1);
1258                                flag |= REF_ISBROKEN;
1259                        }
1260                        add_entry_to_dir(dir,
1261                                         create_ref_entry(refname.buf, sha1, flag, 1));
1262                }
1263                strbuf_setlen(&refname, dirnamelen);
1264        }
1265        strbuf_release(&refname);
1266        closedir(d);
1267}
1268
1269static struct ref_dir *get_loose_refs(struct ref_cache *refs)
1270{
1271        if (!refs->loose) {
1272                /*
1273                 * Mark the top-level directory complete because we
1274                 * are about to read the only subdirectory that can
1275                 * hold references:
1276                 */
1277                refs->loose = create_dir_entry(refs, "", 0, 0);
1278                /*
1279                 * Create an incomplete entry for "refs/":
1280                 */
1281                add_entry_to_dir(get_ref_dir(refs->loose),
1282                                 create_dir_entry(refs, "refs/", 5, 1));
1283        }
1284        return get_ref_dir(refs->loose);
1285}
1286
1287/* We allow "recursive" symbolic refs. Only within reason, though */
1288#define MAXDEPTH 5
1289#define MAXREFLEN (1024)
1290
1291/*
1292 * Called by resolve_gitlink_ref_recursive() after it failed to read
1293 * from the loose refs in ref_cache refs. Find <refname> in the
1294 * packed-refs file for the submodule.
1295 */
1296static int resolve_gitlink_packed_ref(struct ref_cache *refs,
1297                                      const char *refname, unsigned char *sha1)
1298{
1299        struct ref_entry *ref;
1300        struct ref_dir *dir = get_packed_refs(refs);
1301
1302        ref = find_ref(dir, refname);
1303        if (ref == NULL)
1304                return -1;
1305
1306        hashcpy(sha1, ref->u.value.sha1);
1307        return 0;
1308}
1309
1310static int resolve_gitlink_ref_recursive(struct ref_cache *refs,
1311                                         const char *refname, unsigned char *sha1,
1312                                         int recursion)
1313{
1314        int fd, len;
1315        char buffer[128], *p;
1316        char *path;
1317
1318        if (recursion > MAXDEPTH || strlen(refname) > MAXREFLEN)
1319                return -1;
1320        path = *refs->name
1321                ? git_path_submodule(refs->name, "%s", refname)
1322                : git_path("%s", refname);
1323        fd = open(path, O_RDONLY);
1324        if (fd < 0)
1325                return resolve_gitlink_packed_ref(refs, refname, sha1);
1326
1327        len = read(fd, buffer, sizeof(buffer)-1);
1328        close(fd);
1329        if (len < 0)
1330                return -1;
1331        while (len && isspace(buffer[len-1]))
1332                len--;
1333        buffer[len] = 0;
1334
1335        /* Was it a detached head or an old-fashioned symlink? */
1336        if (!get_sha1_hex(buffer, sha1))
1337                return 0;
1338
1339        /* Symref? */
1340        if (strncmp(buffer, "ref:", 4))
1341                return -1;
1342        p = buffer + 4;
1343        while (isspace(*p))
1344                p++;
1345
1346        return resolve_gitlink_ref_recursive(refs, p, sha1, recursion+1);
1347}
1348
1349int resolve_gitlink_ref(const char *path, const char *refname, unsigned char *sha1)
1350{
1351        int len = strlen(path), retval;
1352        char *submodule;
1353        struct ref_cache *refs;
1354
1355        while (len && path[len-1] == '/')
1356                len--;
1357        if (!len)
1358                return -1;
1359        submodule = xstrndup(path, len);
1360        refs = get_ref_cache(submodule);
1361        free(submodule);
1362
1363        retval = resolve_gitlink_ref_recursive(refs, refname, sha1, 0);
1364        return retval;
1365}
1366
1367/*
1368 * Return the ref_entry for the given refname from the packed
1369 * references.  If it does not exist, return NULL.
1370 */
1371static struct ref_entry *get_packed_ref(const char *refname)
1372{
1373        return find_ref(get_packed_refs(&ref_cache), refname);
1374}
1375
1376/*
1377 * A loose ref file doesn't exist; check for a packed ref.  The
1378 * options are forwarded from resolve_safe_unsafe().
1379 */
1380static const char *handle_missing_loose_ref(const char *refname,
1381                                            int resolve_flags,
1382                                            unsigned char *sha1,
1383                                            int *flags)
1384{
1385        struct ref_entry *entry;
1386
1387        /*
1388         * The loose reference file does not exist; check for a packed
1389         * reference.
1390         */
1391        entry = get_packed_ref(refname);
1392        if (entry) {
1393                hashcpy(sha1, entry->u.value.sha1);
1394                if (flags)
1395                        *flags |= REF_ISPACKED;
1396                return refname;
1397        }
1398        /* The reference is not a packed reference, either. */
1399        if (resolve_flags & RESOLVE_REF_READING) {
1400                return NULL;
1401        } else {
1402                hashclr(sha1);
1403                return refname;
1404        }
1405}
1406
1407/* This function needs to return a meaningful errno on failure */
1408const char *resolve_ref_unsafe(const char *refname, int resolve_flags, unsigned char *sha1, int *flags)
1409{
1410        int depth = MAXDEPTH;
1411        ssize_t len;
1412        char buffer[256];
1413        static char refname_buffer[256];
1414
1415        if (flags)
1416                *flags = 0;
1417
1418        if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL)) {
1419                errno = EINVAL;
1420                return NULL;
1421        }
1422        for (;;) {
1423                char path[PATH_MAX];
1424                struct stat st;
1425                char *buf;
1426                int fd;
1427
1428                if (--depth < 0) {
1429                        errno = ELOOP;
1430                        return NULL;
1431                }
1432
1433                git_snpath(path, sizeof(path), "%s", refname);
1434
1435                /*
1436                 * We might have to loop back here to avoid a race
1437                 * condition: first we lstat() the file, then we try
1438                 * to read it as a link or as a file.  But if somebody
1439                 * changes the type of the file (file <-> directory
1440                 * <-> symlink) between the lstat() and reading, then
1441                 * we don't want to report that as an error but rather
1442                 * try again starting with the lstat().
1443                 */
1444        stat_ref:
1445                if (lstat(path, &st) < 0) {
1446                        if (errno == ENOENT)
1447                                return handle_missing_loose_ref(refname,
1448                                                resolve_flags, sha1, flags);
1449                        else
1450                                return NULL;
1451                }
1452
1453                /* Follow "normalized" - ie "refs/.." symlinks by hand */
1454                if (S_ISLNK(st.st_mode)) {
1455                        len = readlink(path, buffer, sizeof(buffer)-1);
1456                        if (len < 0) {
1457                                if (errno == ENOENT || errno == EINVAL)
1458                                        /* inconsistent with lstat; retry */
1459                                        goto stat_ref;
1460                                else
1461                                        return NULL;
1462                        }
1463                        buffer[len] = 0;
1464                        if (starts_with(buffer, "refs/") &&
1465                                        !check_refname_format(buffer, 0)) {
1466                                strcpy(refname_buffer, buffer);
1467                                refname = refname_buffer;
1468                                if (flags)
1469                                        *flags |= REF_ISSYMREF;
1470                                if (resolve_flags & RESOLVE_REF_NO_RECURSE) {
1471                                        hashclr(sha1);
1472                                        return refname;
1473                                }
1474                                continue;
1475                        }
1476                }
1477
1478                /* Is it a directory? */
1479                if (S_ISDIR(st.st_mode)) {
1480                        errno = EISDIR;
1481                        return NULL;
1482                }
1483
1484                /*
1485                 * Anything else, just open it and try to use it as
1486                 * a ref
1487                 */
1488                fd = open(path, O_RDONLY);
1489                if (fd < 0) {
1490                        if (errno == ENOENT)
1491                                /* inconsistent with lstat; retry */
1492                                goto stat_ref;
1493                        else
1494                                return NULL;
1495                }
1496                len = read_in_full(fd, buffer, sizeof(buffer)-1);
1497                if (len < 0) {
1498                        int save_errno = errno;
1499                        close(fd);
1500                        errno = save_errno;
1501                        return NULL;
1502                }
1503                close(fd);
1504                while (len && isspace(buffer[len-1]))
1505                        len--;
1506                buffer[len] = '\0';
1507
1508                /*
1509                 * Is it a symbolic ref?
1510                 */
1511                if (!starts_with(buffer, "ref:")) {
1512                        /*
1513                         * Please note that FETCH_HEAD has a second
1514                         * line containing other data.
1515                         */
1516                        if (get_sha1_hex(buffer, sha1) ||
1517                            (buffer[40] != '\0' && !isspace(buffer[40]))) {
1518                                if (flags)
1519                                        *flags |= REF_ISBROKEN;
1520                                errno = EINVAL;
1521                                return NULL;
1522                        }
1523                        return refname;
1524                }
1525                if (flags)
1526                        *flags |= REF_ISSYMREF;
1527                buf = buffer + 4;
1528                while (isspace(*buf))
1529                        buf++;
1530                refname = strcpy(refname_buffer, buf);
1531                if (resolve_flags & RESOLVE_REF_NO_RECURSE) {
1532                        hashclr(sha1);
1533                        return refname;
1534                }
1535                if (check_refname_format(buf, REFNAME_ALLOW_ONELEVEL)) {
1536                        if (flags)
1537                                *flags |= REF_ISBROKEN;
1538                        errno = EINVAL;
1539                        return NULL;
1540                }
1541        }
1542}
1543
1544char *resolve_refdup(const char *ref, int resolve_flags, unsigned char *sha1, int *flags)
1545{
1546        const char *ret = resolve_ref_unsafe(ref, resolve_flags, sha1, flags);
1547        return ret ? xstrdup(ret) : NULL;
1548}
1549
1550/* The argument to filter_refs */
1551struct ref_filter {
1552        const char *pattern;
1553        each_ref_fn *fn;
1554        void *cb_data;
1555};
1556
1557int read_ref_full(const char *refname, int resolve_flags, unsigned char *sha1, int *flags)
1558{
1559        if (resolve_ref_unsafe(refname, resolve_flags, sha1, flags))
1560                return 0;
1561        return -1;
1562}
1563
1564int read_ref(const char *refname, unsigned char *sha1)
1565{
1566        return read_ref_full(refname, RESOLVE_REF_READING, sha1, NULL);
1567}
1568
1569int ref_exists(const char *refname)
1570{
1571        unsigned char sha1[20];
1572        return !!resolve_ref_unsafe(refname, RESOLVE_REF_READING, sha1, NULL);
1573}
1574
1575static int filter_refs(const char *refname, const unsigned char *sha1, int flags,
1576                       void *data)
1577{
1578        struct ref_filter *filter = (struct ref_filter *)data;
1579        if (wildmatch(filter->pattern, refname, 0, NULL))
1580                return 0;
1581        return filter->fn(refname, sha1, flags, filter->cb_data);
1582}
1583
1584enum peel_status {
1585        /* object was peeled successfully: */
1586        PEEL_PEELED = 0,
1587
1588        /*
1589         * object cannot be peeled because the named object (or an
1590         * object referred to by a tag in the peel chain), does not
1591         * exist.
1592         */
1593        PEEL_INVALID = -1,
1594
1595        /* object cannot be peeled because it is not a tag: */
1596        PEEL_NON_TAG = -2,
1597
1598        /* ref_entry contains no peeled value because it is a symref: */
1599        PEEL_IS_SYMREF = -3,
1600
1601        /*
1602         * ref_entry cannot be peeled because it is broken (i.e., the
1603         * symbolic reference cannot even be resolved to an object
1604         * name):
1605         */
1606        PEEL_BROKEN = -4
1607};
1608
1609/*
1610 * Peel the named object; i.e., if the object is a tag, resolve the
1611 * tag recursively until a non-tag is found.  If successful, store the
1612 * result to sha1 and return PEEL_PEELED.  If the object is not a tag
1613 * or is not valid, return PEEL_NON_TAG or PEEL_INVALID, respectively,
1614 * and leave sha1 unchanged.
1615 */
1616static enum peel_status peel_object(const unsigned char *name, unsigned char *sha1)
1617{
1618        struct object *o = lookup_unknown_object(name);
1619
1620        if (o->type == OBJ_NONE) {
1621                int type = sha1_object_info(name, NULL);
1622                if (type < 0 || !object_as_type(o, type, 0))
1623                        return PEEL_INVALID;
1624        }
1625
1626        if (o->type != OBJ_TAG)
1627                return PEEL_NON_TAG;
1628
1629        o = deref_tag_noverify(o);
1630        if (!o)
1631                return PEEL_INVALID;
1632
1633        hashcpy(sha1, o->sha1);
1634        return PEEL_PEELED;
1635}
1636
1637/*
1638 * Peel the entry (if possible) and return its new peel_status.  If
1639 * repeel is true, re-peel the entry even if there is an old peeled
1640 * value that is already stored in it.
1641 *
1642 * It is OK to call this function with a packed reference entry that
1643 * might be stale and might even refer to an object that has since
1644 * been garbage-collected.  In such a case, if the entry has
1645 * REF_KNOWS_PEELED then leave the status unchanged and return
1646 * PEEL_PEELED or PEEL_NON_TAG; otherwise, return PEEL_INVALID.
1647 */
1648static enum peel_status peel_entry(struct ref_entry *entry, int repeel)
1649{
1650        enum peel_status status;
1651
1652        if (entry->flag & REF_KNOWS_PEELED) {
1653                if (repeel) {
1654                        entry->flag &= ~REF_KNOWS_PEELED;
1655                        hashclr(entry->u.value.peeled);
1656                } else {
1657                        return is_null_sha1(entry->u.value.peeled) ?
1658                                PEEL_NON_TAG : PEEL_PEELED;
1659                }
1660        }
1661        if (entry->flag & REF_ISBROKEN)
1662                return PEEL_BROKEN;
1663        if (entry->flag & REF_ISSYMREF)
1664                return PEEL_IS_SYMREF;
1665
1666        status = peel_object(entry->u.value.sha1, entry->u.value.peeled);
1667        if (status == PEEL_PEELED || status == PEEL_NON_TAG)
1668                entry->flag |= REF_KNOWS_PEELED;
1669        return status;
1670}
1671
1672int peel_ref(const char *refname, unsigned char *sha1)
1673{
1674        int flag;
1675        unsigned char base[20];
1676
1677        if (current_ref && (current_ref->name == refname
1678                            || !strcmp(current_ref->name, refname))) {
1679                if (peel_entry(current_ref, 0))
1680                        return -1;
1681                hashcpy(sha1, current_ref->u.value.peeled);
1682                return 0;
1683        }
1684
1685        if (read_ref_full(refname, RESOLVE_REF_READING, base, &flag))
1686                return -1;
1687
1688        /*
1689         * If the reference is packed, read its ref_entry from the
1690         * cache in the hope that we already know its peeled value.
1691         * We only try this optimization on packed references because
1692         * (a) forcing the filling of the loose reference cache could
1693         * be expensive and (b) loose references anyway usually do not
1694         * have REF_KNOWS_PEELED.
1695         */
1696        if (flag & REF_ISPACKED) {
1697                struct ref_entry *r = get_packed_ref(refname);
1698                if (r) {
1699                        if (peel_entry(r, 0))
1700                                return -1;
1701                        hashcpy(sha1, r->u.value.peeled);
1702                        return 0;
1703                }
1704        }
1705
1706        return peel_object(base, sha1);
1707}
1708
1709struct warn_if_dangling_data {
1710        FILE *fp;
1711        const char *refname;
1712        const struct string_list *refnames;
1713        const char *msg_fmt;
1714};
1715
1716static int warn_if_dangling_symref(const char *refname, const unsigned char *sha1,
1717                                   int flags, void *cb_data)
1718{
1719        struct warn_if_dangling_data *d = cb_data;
1720        const char *resolves_to;
1721        unsigned char junk[20];
1722
1723        if (!(flags & REF_ISSYMREF))
1724                return 0;
1725
1726        resolves_to = resolve_ref_unsafe(refname, 0, junk, NULL);
1727        if (!resolves_to
1728            || (d->refname
1729                ? strcmp(resolves_to, d->refname)
1730                : !string_list_has_string(d->refnames, resolves_to))) {
1731                return 0;
1732        }
1733
1734        fprintf(d->fp, d->msg_fmt, refname);
1735        fputc('\n', d->fp);
1736        return 0;
1737}
1738
1739void warn_dangling_symref(FILE *fp, const char *msg_fmt, const char *refname)
1740{
1741        struct warn_if_dangling_data data;
1742
1743        data.fp = fp;
1744        data.refname = refname;
1745        data.refnames = NULL;
1746        data.msg_fmt = msg_fmt;
1747        for_each_rawref(warn_if_dangling_symref, &data);
1748}
1749
1750void warn_dangling_symrefs(FILE *fp, const char *msg_fmt, const struct string_list *refnames)
1751{
1752        struct warn_if_dangling_data data;
1753
1754        data.fp = fp;
1755        data.refname = NULL;
1756        data.refnames = refnames;
1757        data.msg_fmt = msg_fmt;
1758        for_each_rawref(warn_if_dangling_symref, &data);
1759}
1760
1761/*
1762 * Call fn for each reference in the specified ref_cache, omitting
1763 * references not in the containing_dir of base.  fn is called for all
1764 * references, including broken ones.  If fn ever returns a non-zero
1765 * value, stop the iteration and return that value; otherwise, return
1766 * 0.
1767 */
1768static int do_for_each_entry(struct ref_cache *refs, const char *base,
1769                             each_ref_entry_fn fn, void *cb_data)
1770{
1771        struct packed_ref_cache *packed_ref_cache;
1772        struct ref_dir *loose_dir;
1773        struct ref_dir *packed_dir;
1774        int retval = 0;
1775
1776        /*
1777         * We must make sure that all loose refs are read before accessing the
1778         * packed-refs file; this avoids a race condition in which loose refs
1779         * are migrated to the packed-refs file by a simultaneous process, but
1780         * our in-memory view is from before the migration. get_packed_ref_cache()
1781         * takes care of making sure our view is up to date with what is on
1782         * disk.
1783         */
1784        loose_dir = get_loose_refs(refs);
1785        if (base && *base) {
1786                loose_dir = find_containing_dir(loose_dir, base, 0);
1787        }
1788        if (loose_dir)
1789                prime_ref_dir(loose_dir);
1790
1791        packed_ref_cache = get_packed_ref_cache(refs);
1792        acquire_packed_ref_cache(packed_ref_cache);
1793        packed_dir = get_packed_ref_dir(packed_ref_cache);
1794        if (base && *base) {
1795                packed_dir = find_containing_dir(packed_dir, base, 0);
1796        }
1797
1798        if (packed_dir && loose_dir) {
1799                sort_ref_dir(packed_dir);
1800                sort_ref_dir(loose_dir);
1801                retval = do_for_each_entry_in_dirs(
1802                                packed_dir, loose_dir, fn, cb_data);
1803        } else if (packed_dir) {
1804                sort_ref_dir(packed_dir);
1805                retval = do_for_each_entry_in_dir(
1806                                packed_dir, 0, fn, cb_data);
1807        } else if (loose_dir) {
1808                sort_ref_dir(loose_dir);
1809                retval = do_for_each_entry_in_dir(
1810                                loose_dir, 0, fn, cb_data);
1811        }
1812
1813        release_packed_ref_cache(packed_ref_cache);
1814        return retval;
1815}
1816
1817/*
1818 * Call fn for each reference in the specified ref_cache for which the
1819 * refname begins with base.  If trim is non-zero, then trim that many
1820 * characters off the beginning of each refname before passing the
1821 * refname to fn.  flags can be DO_FOR_EACH_INCLUDE_BROKEN to include
1822 * broken references in the iteration.  If fn ever returns a non-zero
1823 * value, stop the iteration and return that value; otherwise, return
1824 * 0.
1825 */
1826static int do_for_each_ref(struct ref_cache *refs, const char *base,
1827                           each_ref_fn fn, int trim, int flags, void *cb_data)
1828{
1829        struct ref_entry_cb data;
1830        data.base = base;
1831        data.trim = trim;
1832        data.flags = flags;
1833        data.fn = fn;
1834        data.cb_data = cb_data;
1835
1836        return do_for_each_entry(refs, base, do_one_ref, &data);
1837}
1838
1839static int do_head_ref(const char *submodule, each_ref_fn fn, void *cb_data)
1840{
1841        unsigned char sha1[20];
1842        int flag;
1843
1844        if (submodule) {
1845                if (resolve_gitlink_ref(submodule, "HEAD", sha1) == 0)
1846                        return fn("HEAD", sha1, 0, cb_data);
1847
1848                return 0;
1849        }
1850
1851        if (!read_ref_full("HEAD", RESOLVE_REF_READING, sha1, &flag))
1852                return fn("HEAD", sha1, flag, cb_data);
1853
1854        return 0;
1855}
1856
1857int head_ref(each_ref_fn fn, void *cb_data)
1858{
1859        return do_head_ref(NULL, fn, cb_data);
1860}
1861
1862int head_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
1863{
1864        return do_head_ref(submodule, fn, cb_data);
1865}
1866
1867int for_each_ref(each_ref_fn fn, void *cb_data)
1868{
1869        return do_for_each_ref(&ref_cache, "", fn, 0, 0, cb_data);
1870}
1871
1872int for_each_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
1873{
1874        return do_for_each_ref(get_ref_cache(submodule), "", fn, 0, 0, cb_data);
1875}
1876
1877int for_each_ref_in(const char *prefix, each_ref_fn fn, void *cb_data)
1878{
1879        return do_for_each_ref(&ref_cache, prefix, fn, strlen(prefix), 0, cb_data);
1880}
1881
1882int for_each_ref_in_submodule(const char *submodule, const char *prefix,
1883                each_ref_fn fn, void *cb_data)
1884{
1885        return do_for_each_ref(get_ref_cache(submodule), prefix, fn, strlen(prefix), 0, cb_data);
1886}
1887
1888int for_each_tag_ref(each_ref_fn fn, void *cb_data)
1889{
1890        return for_each_ref_in("refs/tags/", fn, cb_data);
1891}
1892
1893int for_each_tag_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
1894{
1895        return for_each_ref_in_submodule(submodule, "refs/tags/", fn, cb_data);
1896}
1897
1898int for_each_branch_ref(each_ref_fn fn, void *cb_data)
1899{
1900        return for_each_ref_in("refs/heads/", fn, cb_data);
1901}
1902
1903int for_each_branch_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
1904{
1905        return for_each_ref_in_submodule(submodule, "refs/heads/", fn, cb_data);
1906}
1907
1908int for_each_remote_ref(each_ref_fn fn, void *cb_data)
1909{
1910        return for_each_ref_in("refs/remotes/", fn, cb_data);
1911}
1912
1913int for_each_remote_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
1914{
1915        return for_each_ref_in_submodule(submodule, "refs/remotes/", fn, cb_data);
1916}
1917
1918int for_each_replace_ref(each_ref_fn fn, void *cb_data)
1919{
1920        return do_for_each_ref(&ref_cache, "refs/replace/", fn, 13, 0, cb_data);
1921}
1922
1923int head_ref_namespaced(each_ref_fn fn, void *cb_data)
1924{
1925        struct strbuf buf = STRBUF_INIT;
1926        int ret = 0;
1927        unsigned char sha1[20];
1928        int flag;
1929
1930        strbuf_addf(&buf, "%sHEAD", get_git_namespace());
1931        if (!read_ref_full(buf.buf, RESOLVE_REF_READING, sha1, &flag))
1932                ret = fn(buf.buf, sha1, flag, cb_data);
1933        strbuf_release(&buf);
1934
1935        return ret;
1936}
1937
1938int for_each_namespaced_ref(each_ref_fn fn, void *cb_data)
1939{
1940        struct strbuf buf = STRBUF_INIT;
1941        int ret;
1942        strbuf_addf(&buf, "%srefs/", get_git_namespace());
1943        ret = do_for_each_ref(&ref_cache, buf.buf, fn, 0, 0, cb_data);
1944        strbuf_release(&buf);
1945        return ret;
1946}
1947
1948int for_each_glob_ref_in(each_ref_fn fn, const char *pattern,
1949        const char *prefix, void *cb_data)
1950{
1951        struct strbuf real_pattern = STRBUF_INIT;
1952        struct ref_filter filter;
1953        int ret;
1954
1955        if (!prefix && !starts_with(pattern, "refs/"))
1956                strbuf_addstr(&real_pattern, "refs/");
1957        else if (prefix)
1958                strbuf_addstr(&real_pattern, prefix);
1959        strbuf_addstr(&real_pattern, pattern);
1960
1961        if (!has_glob_specials(pattern)) {
1962                /* Append implied '/' '*' if not present. */
1963                if (real_pattern.buf[real_pattern.len - 1] != '/')
1964                        strbuf_addch(&real_pattern, '/');
1965                /* No need to check for '*', there is none. */
1966                strbuf_addch(&real_pattern, '*');
1967        }
1968
1969        filter.pattern = real_pattern.buf;
1970        filter.fn = fn;
1971        filter.cb_data = cb_data;
1972        ret = for_each_ref(filter_refs, &filter);
1973
1974        strbuf_release(&real_pattern);
1975        return ret;
1976}
1977
1978int for_each_glob_ref(each_ref_fn fn, const char *pattern, void *cb_data)
1979{
1980        return for_each_glob_ref_in(fn, pattern, NULL, cb_data);
1981}
1982
1983int for_each_rawref(each_ref_fn fn, void *cb_data)
1984{
1985        return do_for_each_ref(&ref_cache, "", fn, 0,
1986                               DO_FOR_EACH_INCLUDE_BROKEN, cb_data);
1987}
1988
1989const char *prettify_refname(const char *name)
1990{
1991        return name + (
1992                starts_with(name, "refs/heads/") ? 11 :
1993                starts_with(name, "refs/tags/") ? 10 :
1994                starts_with(name, "refs/remotes/") ? 13 :
1995                0);
1996}
1997
1998static const char *ref_rev_parse_rules[] = {
1999        "%.*s",
2000        "refs/%.*s",
2001        "refs/tags/%.*s",
2002        "refs/heads/%.*s",
2003        "refs/remotes/%.*s",
2004        "refs/remotes/%.*s/HEAD",
2005        NULL
2006};
2007
2008int refname_match(const char *abbrev_name, const char *full_name)
2009{
2010        const char **p;
2011        const int abbrev_name_len = strlen(abbrev_name);
2012
2013        for (p = ref_rev_parse_rules; *p; p++) {
2014                if (!strcmp(full_name, mkpath(*p, abbrev_name_len, abbrev_name))) {
2015                        return 1;
2016                }
2017        }
2018
2019        return 0;
2020}
2021
2022/* This function should make sure errno is meaningful on error */
2023static struct ref_lock *verify_lock(struct ref_lock *lock,
2024        const unsigned char *old_sha1, int mustexist)
2025{
2026        if (read_ref_full(lock->ref_name,
2027                          mustexist ? RESOLVE_REF_READING : 0,
2028                          lock->old_sha1, NULL)) {
2029                int save_errno = errno;
2030                error("Can't verify ref %s", lock->ref_name);
2031                unlock_ref(lock);
2032                errno = save_errno;
2033                return NULL;
2034        }
2035        if (hashcmp(lock->old_sha1, old_sha1)) {
2036                error("Ref %s is at %s but expected %s", lock->ref_name,
2037                        sha1_to_hex(lock->old_sha1), sha1_to_hex(old_sha1));
2038                unlock_ref(lock);
2039                errno = EBUSY;
2040                return NULL;
2041        }
2042        return lock;
2043}
2044
2045static int remove_empty_directories(const char *file)
2046{
2047        /* we want to create a file but there is a directory there;
2048         * if that is an empty directory (or a directory that contains
2049         * only empty directories), remove them.
2050         */
2051        struct strbuf path;
2052        int result, save_errno;
2053
2054        strbuf_init(&path, 20);
2055        strbuf_addstr(&path, file);
2056
2057        result = remove_dir_recursively(&path, REMOVE_DIR_EMPTY_ONLY);
2058        save_errno = errno;
2059
2060        strbuf_release(&path);
2061        errno = save_errno;
2062
2063        return result;
2064}
2065
2066/*
2067 * *string and *len will only be substituted, and *string returned (for
2068 * later free()ing) if the string passed in is a magic short-hand form
2069 * to name a branch.
2070 */
2071static char *substitute_branch_name(const char **string, int *len)
2072{
2073        struct strbuf buf = STRBUF_INIT;
2074        int ret = interpret_branch_name(*string, *len, &buf);
2075
2076        if (ret == *len) {
2077                size_t size;
2078                *string = strbuf_detach(&buf, &size);
2079                *len = size;
2080                return (char *)*string;
2081        }
2082
2083        return NULL;
2084}
2085
2086int dwim_ref(const char *str, int len, unsigned char *sha1, char **ref)
2087{
2088        char *last_branch = substitute_branch_name(&str, &len);
2089        const char **p, *r;
2090        int refs_found = 0;
2091
2092        *ref = NULL;
2093        for (p = ref_rev_parse_rules; *p; p++) {
2094                char fullref[PATH_MAX];
2095                unsigned char sha1_from_ref[20];
2096                unsigned char *this_result;
2097                int flag;
2098
2099                this_result = refs_found ? sha1_from_ref : sha1;
2100                mksnpath(fullref, sizeof(fullref), *p, len, str);
2101                r = resolve_ref_unsafe(fullref, RESOLVE_REF_READING,
2102                                       this_result, &flag);
2103                if (r) {
2104                        if (!refs_found++)
2105                                *ref = xstrdup(r);
2106                        if (!warn_ambiguous_refs)
2107                                break;
2108                } else if ((flag & REF_ISSYMREF) && strcmp(fullref, "HEAD")) {
2109                        warning("ignoring dangling symref %s.", fullref);
2110                } else if ((flag & REF_ISBROKEN) && strchr(fullref, '/')) {
2111                        warning("ignoring broken ref %s.", fullref);
2112                }
2113        }
2114        free(last_branch);
2115        return refs_found;
2116}
2117
2118int dwim_log(const char *str, int len, unsigned char *sha1, char **log)
2119{
2120        char *last_branch = substitute_branch_name(&str, &len);
2121        const char **p;
2122        int logs_found = 0;
2123
2124        *log = NULL;
2125        for (p = ref_rev_parse_rules; *p; p++) {
2126                unsigned char hash[20];
2127                char path[PATH_MAX];
2128                const char *ref, *it;
2129
2130                mksnpath(path, sizeof(path), *p, len, str);
2131                ref = resolve_ref_unsafe(path, RESOLVE_REF_READING,
2132                                         hash, NULL);
2133                if (!ref)
2134                        continue;
2135                if (reflog_exists(path))
2136                        it = path;
2137                else if (strcmp(ref, path) && reflog_exists(ref))
2138                        it = ref;
2139                else
2140                        continue;
2141                if (!logs_found++) {
2142                        *log = xstrdup(it);
2143                        hashcpy(sha1, hash);
2144                }
2145                if (!warn_ambiguous_refs)
2146                        break;
2147        }
2148        free(last_branch);
2149        return logs_found;
2150}
2151
2152/*
2153 * Locks a ref returning the lock on success and NULL on failure.
2154 * On failure errno is set to something meaningful.
2155 */
2156static struct ref_lock *lock_ref_sha1_basic(const char *refname,
2157                                            const unsigned char *old_sha1,
2158                                            const struct string_list *skip,
2159                                            int flags, int *type_p)
2160{
2161        char *ref_file;
2162        const char *orig_refname = refname;
2163        struct ref_lock *lock;
2164        int last_errno = 0;
2165        int type, lflags;
2166        int mustexist = (old_sha1 && !is_null_sha1(old_sha1));
2167        int resolve_flags = 0;
2168        int missing = 0;
2169        int attempts_remaining = 3;
2170
2171        if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL)) {
2172                errno = EINVAL;
2173                return NULL;
2174        }
2175
2176        lock = xcalloc(1, sizeof(struct ref_lock));
2177        lock->lock_fd = -1;
2178
2179        if (mustexist)
2180                resolve_flags |= RESOLVE_REF_READING;
2181        if (flags & REF_NODEREF && flags & REF_DELETING)
2182                resolve_flags |= RESOLVE_REF_NO_RECURSE;
2183
2184        refname = resolve_ref_unsafe(refname, resolve_flags,
2185                                     lock->old_sha1, &type);
2186        if (!refname && errno == EISDIR) {
2187                /* we are trying to lock foo but we used to
2188                 * have foo/bar which now does not exist;
2189                 * it is normal for the empty directory 'foo'
2190                 * to remain.
2191                 */
2192                ref_file = git_path("%s", orig_refname);
2193                if (remove_empty_directories(ref_file)) {
2194                        last_errno = errno;
2195                        error("there are still refs under '%s'", orig_refname);
2196                        goto error_return;
2197                }
2198                refname = resolve_ref_unsafe(orig_refname, resolve_flags,
2199                                             lock->old_sha1, &type);
2200        }
2201        if (type_p)
2202            *type_p = type;
2203        if (!refname) {
2204                last_errno = errno;
2205                error("unable to resolve reference %s: %s",
2206                        orig_refname, strerror(errno));
2207                goto error_return;
2208        }
2209        missing = is_null_sha1(lock->old_sha1);
2210        /* When the ref did not exist and we are creating it,
2211         * make sure there is no existing ref that is packed
2212         * whose name begins with our refname, nor a ref whose
2213         * name is a proper prefix of our refname.
2214         */
2215        if (missing &&
2216             !is_refname_available(refname, skip, get_packed_refs(&ref_cache))) {
2217                last_errno = ENOTDIR;
2218                goto error_return;
2219        }
2220
2221        lock->lk = xcalloc(1, sizeof(struct lock_file));
2222
2223        lflags = 0;
2224        if (flags & REF_NODEREF) {
2225                refname = orig_refname;
2226                lflags |= LOCK_NO_DEREF;
2227        }
2228        lock->ref_name = xstrdup(refname);
2229        lock->orig_ref_name = xstrdup(orig_refname);
2230        ref_file = git_path("%s", refname);
2231        if (missing)
2232                lock->force_write = 1;
2233        if ((flags & REF_NODEREF) && (type & REF_ISSYMREF))
2234                lock->force_write = 1;
2235
2236 retry:
2237        switch (safe_create_leading_directories(ref_file)) {
2238        case SCLD_OK:
2239                break; /* success */
2240        case SCLD_VANISHED:
2241                if (--attempts_remaining > 0)
2242                        goto retry;
2243                /* fall through */
2244        default:
2245                last_errno = errno;
2246                error("unable to create directory for %s", ref_file);
2247                goto error_return;
2248        }
2249
2250        lock->lock_fd = hold_lock_file_for_update(lock->lk, ref_file, lflags);
2251        if (lock->lock_fd < 0) {
2252                if (errno == ENOENT && --attempts_remaining > 0)
2253                        /*
2254                         * Maybe somebody just deleted one of the
2255                         * directories leading to ref_file.  Try
2256                         * again:
2257                         */
2258                        goto retry;
2259                else
2260                        unable_to_lock_die(ref_file, errno);
2261        }
2262        return old_sha1 ? verify_lock(lock, old_sha1, mustexist) : lock;
2263
2264 error_return:
2265        unlock_ref(lock);
2266        errno = last_errno;
2267        return NULL;
2268}
2269
2270struct ref_lock *lock_any_ref_for_update(const char *refname,
2271                                         const unsigned char *old_sha1,
2272                                         int flags, int *type_p)
2273{
2274        return lock_ref_sha1_basic(refname, old_sha1, NULL, flags, type_p);
2275}
2276
2277/*
2278 * Write an entry to the packed-refs file for the specified refname.
2279 * If peeled is non-NULL, write it as the entry's peeled value.
2280 */
2281static void write_packed_entry(FILE *fh, char *refname, unsigned char *sha1,
2282                               unsigned char *peeled)
2283{
2284        fprintf_or_die(fh, "%s %s\n", sha1_to_hex(sha1), refname);
2285        if (peeled)
2286                fprintf_or_die(fh, "^%s\n", sha1_to_hex(peeled));
2287}
2288
2289/*
2290 * An each_ref_entry_fn that writes the entry to a packed-refs file.
2291 */
2292static int write_packed_entry_fn(struct ref_entry *entry, void *cb_data)
2293{
2294        enum peel_status peel_status = peel_entry(entry, 0);
2295
2296        if (peel_status != PEEL_PEELED && peel_status != PEEL_NON_TAG)
2297                error("internal error: %s is not a valid packed reference!",
2298                      entry->name);
2299        write_packed_entry(cb_data, entry->name, entry->u.value.sha1,
2300                           peel_status == PEEL_PEELED ?
2301                           entry->u.value.peeled : NULL);
2302        return 0;
2303}
2304
2305/* This should return a meaningful errno on failure */
2306int lock_packed_refs(int flags)
2307{
2308        struct packed_ref_cache *packed_ref_cache;
2309
2310        if (hold_lock_file_for_update(&packlock, git_path("packed-refs"), flags) < 0)
2311                return -1;
2312        /*
2313         * Get the current packed-refs while holding the lock.  If the
2314         * packed-refs file has been modified since we last read it,
2315         * this will automatically invalidate the cache and re-read
2316         * the packed-refs file.
2317         */
2318        packed_ref_cache = get_packed_ref_cache(&ref_cache);
2319        packed_ref_cache->lock = &packlock;
2320        /* Increment the reference count to prevent it from being freed: */
2321        acquire_packed_ref_cache(packed_ref_cache);
2322        return 0;
2323}
2324
2325/*
2326 * Commit the packed refs changes.
2327 * On error we must make sure that errno contains a meaningful value.
2328 */
2329int commit_packed_refs(void)
2330{
2331        struct packed_ref_cache *packed_ref_cache =
2332                get_packed_ref_cache(&ref_cache);
2333        int error = 0;
2334        int save_errno = 0;
2335        FILE *out;
2336
2337        if (!packed_ref_cache->lock)
2338                die("internal error: packed-refs not locked");
2339
2340        out = fdopen_lock_file(packed_ref_cache->lock, "w");
2341        if (!out)
2342                die_errno("unable to fdopen packed-refs descriptor");
2343
2344        fprintf_or_die(out, "%s", PACKED_REFS_HEADER);
2345        do_for_each_entry_in_dir(get_packed_ref_dir(packed_ref_cache),
2346                                 0, write_packed_entry_fn, out);
2347
2348        if (commit_lock_file(packed_ref_cache->lock)) {
2349                save_errno = errno;
2350                error = -1;
2351        }
2352        packed_ref_cache->lock = NULL;
2353        release_packed_ref_cache(packed_ref_cache);
2354        errno = save_errno;
2355        return error;
2356}
2357
2358void rollback_packed_refs(void)
2359{
2360        struct packed_ref_cache *packed_ref_cache =
2361                get_packed_ref_cache(&ref_cache);
2362
2363        if (!packed_ref_cache->lock)
2364                die("internal error: packed-refs not locked");
2365        rollback_lock_file(packed_ref_cache->lock);
2366        packed_ref_cache->lock = NULL;
2367        release_packed_ref_cache(packed_ref_cache);
2368        clear_packed_ref_cache(&ref_cache);
2369}
2370
2371struct ref_to_prune {
2372        struct ref_to_prune *next;
2373        unsigned char sha1[20];
2374        char name[FLEX_ARRAY];
2375};
2376
2377struct pack_refs_cb_data {
2378        unsigned int flags;
2379        struct ref_dir *packed_refs;
2380        struct ref_to_prune *ref_to_prune;
2381};
2382
2383/*
2384 * An each_ref_entry_fn that is run over loose references only.  If
2385 * the loose reference can be packed, add an entry in the packed ref
2386 * cache.  If the reference should be pruned, also add it to
2387 * ref_to_prune in the pack_refs_cb_data.
2388 */
2389static int pack_if_possible_fn(struct ref_entry *entry, void *cb_data)
2390{
2391        struct pack_refs_cb_data *cb = cb_data;
2392        enum peel_status peel_status;
2393        struct ref_entry *packed_entry;
2394        int is_tag_ref = starts_with(entry->name, "refs/tags/");
2395
2396        /* ALWAYS pack tags */
2397        if (!(cb->flags & PACK_REFS_ALL) && !is_tag_ref)
2398                return 0;
2399
2400        /* Do not pack symbolic or broken refs: */
2401        if ((entry->flag & REF_ISSYMREF) || !ref_resolves_to_object(entry))
2402                return 0;
2403
2404        /* Add a packed ref cache entry equivalent to the loose entry. */
2405        peel_status = peel_entry(entry, 1);
2406        if (peel_status != PEEL_PEELED && peel_status != PEEL_NON_TAG)
2407                die("internal error peeling reference %s (%s)",
2408                    entry->name, sha1_to_hex(entry->u.value.sha1));
2409        packed_entry = find_ref(cb->packed_refs, entry->name);
2410        if (packed_entry) {
2411                /* Overwrite existing packed entry with info from loose entry */
2412                packed_entry->flag = REF_ISPACKED | REF_KNOWS_PEELED;
2413                hashcpy(packed_entry->u.value.sha1, entry->u.value.sha1);
2414        } else {
2415                packed_entry = create_ref_entry(entry->name, entry->u.value.sha1,
2416                                                REF_ISPACKED | REF_KNOWS_PEELED, 0);
2417                add_ref(cb->packed_refs, packed_entry);
2418        }
2419        hashcpy(packed_entry->u.value.peeled, entry->u.value.peeled);
2420
2421        /* Schedule the loose reference for pruning if requested. */
2422        if ((cb->flags & PACK_REFS_PRUNE)) {
2423                int namelen = strlen(entry->name) + 1;
2424                struct ref_to_prune *n = xcalloc(1, sizeof(*n) + namelen);
2425                hashcpy(n->sha1, entry->u.value.sha1);
2426                strcpy(n->name, entry->name);
2427                n->next = cb->ref_to_prune;
2428                cb->ref_to_prune = n;
2429        }
2430        return 0;
2431}
2432
2433/*
2434 * Remove empty parents, but spare refs/ and immediate subdirs.
2435 * Note: munges *name.
2436 */
2437static void try_remove_empty_parents(char *name)
2438{
2439        char *p, *q;
2440        int i;
2441        p = name;
2442        for (i = 0; i < 2; i++) { /* refs/{heads,tags,...}/ */
2443                while (*p && *p != '/')
2444                        p++;
2445                /* tolerate duplicate slashes; see check_refname_format() */
2446                while (*p == '/')
2447                        p++;
2448        }
2449        for (q = p; *q; q++)
2450                ;
2451        while (1) {
2452                while (q > p && *q != '/')
2453                        q--;
2454                while (q > p && *(q-1) == '/')
2455                        q--;
2456                if (q == p)
2457                        break;
2458                *q = '\0';
2459                if (rmdir(git_path("%s", name)))
2460                        break;
2461        }
2462}
2463
2464/* make sure nobody touched the ref, and unlink */
2465static void prune_ref(struct ref_to_prune *r)
2466{
2467        struct ref_transaction *transaction;
2468        struct strbuf err = STRBUF_INIT;
2469
2470        if (check_refname_format(r->name, 0))
2471                return;
2472
2473        transaction = ref_transaction_begin(&err);
2474        if (!transaction ||
2475            ref_transaction_delete(transaction, r->name, r->sha1,
2476                                   REF_ISPRUNING, 1, NULL, &err) ||
2477            ref_transaction_commit(transaction, &err)) {
2478                ref_transaction_free(transaction);
2479                error("%s", err.buf);
2480                strbuf_release(&err);
2481                return;
2482        }
2483        ref_transaction_free(transaction);
2484        strbuf_release(&err);
2485        try_remove_empty_parents(r->name);
2486}
2487
2488static void prune_refs(struct ref_to_prune *r)
2489{
2490        while (r) {
2491                prune_ref(r);
2492                r = r->next;
2493        }
2494}
2495
2496int pack_refs(unsigned int flags)
2497{
2498        struct pack_refs_cb_data cbdata;
2499
2500        memset(&cbdata, 0, sizeof(cbdata));
2501        cbdata.flags = flags;
2502
2503        lock_packed_refs(LOCK_DIE_ON_ERROR);
2504        cbdata.packed_refs = get_packed_refs(&ref_cache);
2505
2506        do_for_each_entry_in_dir(get_loose_refs(&ref_cache), 0,
2507                                 pack_if_possible_fn, &cbdata);
2508
2509        if (commit_packed_refs())
2510                die_errno("unable to overwrite old ref-pack file");
2511
2512        prune_refs(cbdata.ref_to_prune);
2513        return 0;
2514}
2515
2516/*
2517 * If entry is no longer needed in packed-refs, add it to the string
2518 * list pointed to by cb_data.  Reasons for deleting entries:
2519 *
2520 * - Entry is broken.
2521 * - Entry is overridden by a loose ref.
2522 * - Entry does not point at a valid object.
2523 *
2524 * In the first and third cases, also emit an error message because these
2525 * are indications of repository corruption.
2526 */
2527static int curate_packed_ref_fn(struct ref_entry *entry, void *cb_data)
2528{
2529        struct string_list *refs_to_delete = cb_data;
2530
2531        if (entry->flag & REF_ISBROKEN) {
2532                /* This shouldn't happen to packed refs. */
2533                error("%s is broken!", entry->name);
2534                string_list_append(refs_to_delete, entry->name);
2535                return 0;
2536        }
2537        if (!has_sha1_file(entry->u.value.sha1)) {
2538                unsigned char sha1[20];
2539                int flags;
2540
2541                if (read_ref_full(entry->name, 0, sha1, &flags))
2542                        /* We should at least have found the packed ref. */
2543                        die("Internal error");
2544                if ((flags & REF_ISSYMREF) || !(flags & REF_ISPACKED)) {
2545                        /*
2546                         * This packed reference is overridden by a
2547                         * loose reference, so it is OK that its value
2548                         * is no longer valid; for example, it might
2549                         * refer to an object that has been garbage
2550                         * collected.  For this purpose we don't even
2551                         * care whether the loose reference itself is
2552                         * invalid, broken, symbolic, etc.  Silently
2553                         * remove the packed reference.
2554                         */
2555                        string_list_append(refs_to_delete, entry->name);
2556                        return 0;
2557                }
2558                /*
2559                 * There is no overriding loose reference, so the fact
2560                 * that this reference doesn't refer to a valid object
2561                 * indicates some kind of repository corruption.
2562                 * Report the problem, then omit the reference from
2563                 * the output.
2564                 */
2565                error("%s does not point to a valid object!", entry->name);
2566                string_list_append(refs_to_delete, entry->name);
2567                return 0;
2568        }
2569
2570        return 0;
2571}
2572
2573int repack_without_refs(const char **refnames, int n, struct strbuf *err)
2574{
2575        struct ref_dir *packed;
2576        struct string_list refs_to_delete = STRING_LIST_INIT_DUP;
2577        struct string_list_item *ref_to_delete;
2578        int i, ret, removed = 0;
2579
2580        /* Look for a packed ref */
2581        for (i = 0; i < n; i++)
2582                if (get_packed_ref(refnames[i]))
2583                        break;
2584
2585        /* Avoid locking if we have nothing to do */
2586        if (i == n)
2587                return 0; /* no refname exists in packed refs */
2588
2589        if (lock_packed_refs(0)) {
2590                if (err) {
2591                        unable_to_lock_message(git_path("packed-refs"), errno,
2592                                               err);
2593                        return -1;
2594                }
2595                unable_to_lock_error(git_path("packed-refs"), errno);
2596                return error("cannot delete '%s' from packed refs", refnames[i]);
2597        }
2598        packed = get_packed_refs(&ref_cache);
2599
2600        /* Remove refnames from the cache */
2601        for (i = 0; i < n; i++)
2602                if (remove_entry(packed, refnames[i]) != -1)
2603                        removed = 1;
2604        if (!removed) {
2605                /*
2606                 * All packed entries disappeared while we were
2607                 * acquiring the lock.
2608                 */
2609                rollback_packed_refs();
2610                return 0;
2611        }
2612
2613        /* Remove any other accumulated cruft */
2614        do_for_each_entry_in_dir(packed, 0, curate_packed_ref_fn, &refs_to_delete);
2615        for_each_string_list_item(ref_to_delete, &refs_to_delete) {
2616                if (remove_entry(packed, ref_to_delete->string) == -1)
2617                        die("internal error");
2618        }
2619
2620        /* Write what remains */
2621        ret = commit_packed_refs();
2622        if (ret && err)
2623                strbuf_addf(err, "unable to overwrite old ref-pack file: %s",
2624                            strerror(errno));
2625        return ret;
2626}
2627
2628static int delete_ref_loose(struct ref_lock *lock, int flag, struct strbuf *err)
2629{
2630        if (!(flag & REF_ISPACKED) || flag & REF_ISSYMREF) {
2631                /*
2632                 * loose.  The loose file name is the same as the
2633                 * lockfile name, minus ".lock":
2634                 */
2635                char *loose_filename = get_locked_file_path(lock->lk);
2636                int res = unlink_or_msg(loose_filename, err);
2637                free(loose_filename);
2638                if (res)
2639                        return 1;
2640        }
2641        return 0;
2642}
2643
2644int delete_ref(const char *refname, const unsigned char *sha1, int delopt)
2645{
2646        struct ref_transaction *transaction;
2647        struct strbuf err = STRBUF_INIT;
2648
2649        transaction = ref_transaction_begin(&err);
2650        if (!transaction ||
2651            ref_transaction_delete(transaction, refname, sha1, delopt,
2652                                   sha1 && !is_null_sha1(sha1), NULL, &err) ||
2653            ref_transaction_commit(transaction, &err)) {
2654                error("%s", err.buf);
2655                ref_transaction_free(transaction);
2656                strbuf_release(&err);
2657                return 1;
2658        }
2659        ref_transaction_free(transaction);
2660        strbuf_release(&err);
2661        return 0;
2662}
2663
2664/*
2665 * People using contrib's git-new-workdir have .git/logs/refs ->
2666 * /some/other/path/.git/logs/refs, and that may live on another device.
2667 *
2668 * IOW, to avoid cross device rename errors, the temporary renamed log must
2669 * live into logs/refs.
2670 */
2671#define TMP_RENAMED_LOG  "logs/refs/.tmp-renamed-log"
2672
2673static int rename_tmp_log(const char *newrefname)
2674{
2675        int attempts_remaining = 4;
2676
2677 retry:
2678        switch (safe_create_leading_directories(git_path("logs/%s", newrefname))) {
2679        case SCLD_OK:
2680                break; /* success */
2681        case SCLD_VANISHED:
2682                if (--attempts_remaining > 0)
2683                        goto retry;
2684                /* fall through */
2685        default:
2686                error("unable to create directory for %s", newrefname);
2687                return -1;
2688        }
2689
2690        if (rename(git_path(TMP_RENAMED_LOG), git_path("logs/%s", newrefname))) {
2691                if ((errno==EISDIR || errno==ENOTDIR) && --attempts_remaining > 0) {
2692                        /*
2693                         * rename(a, b) when b is an existing
2694                         * directory ought to result in ISDIR, but
2695                         * Solaris 5.8 gives ENOTDIR.  Sheesh.
2696                         */
2697                        if (remove_empty_directories(git_path("logs/%s", newrefname))) {
2698                                error("Directory not empty: logs/%s", newrefname);
2699                                return -1;
2700                        }
2701                        goto retry;
2702                } else if (errno == ENOENT && --attempts_remaining > 0) {
2703                        /*
2704                         * Maybe another process just deleted one of
2705                         * the directories in the path to newrefname.
2706                         * Try again from the beginning.
2707                         */
2708                        goto retry;
2709                } else {
2710                        error("unable to move logfile "TMP_RENAMED_LOG" to logs/%s: %s",
2711                                newrefname, strerror(errno));
2712                        return -1;
2713                }
2714        }
2715        return 0;
2716}
2717
2718static int rename_ref_available(const char *oldname, const char *newname)
2719{
2720        struct string_list skip = STRING_LIST_INIT_NODUP;
2721        int ret;
2722
2723        string_list_insert(&skip, oldname);
2724        ret = is_refname_available(newname, &skip, get_packed_refs(&ref_cache))
2725            && is_refname_available(newname, &skip, get_loose_refs(&ref_cache));
2726        string_list_clear(&skip, 0);
2727        return ret;
2728}
2729
2730static int write_ref_sha1(struct ref_lock *lock, const unsigned char *sha1,
2731                          const char *logmsg);
2732
2733int rename_ref(const char *oldrefname, const char *newrefname, const char *logmsg)
2734{
2735        unsigned char sha1[20], orig_sha1[20];
2736        int flag = 0, logmoved = 0;
2737        struct ref_lock *lock;
2738        struct stat loginfo;
2739        int log = !lstat(git_path("logs/%s", oldrefname), &loginfo);
2740        const char *symref = NULL;
2741
2742        if (log && S_ISLNK(loginfo.st_mode))
2743                return error("reflog for %s is a symlink", oldrefname);
2744
2745        symref = resolve_ref_unsafe(oldrefname, RESOLVE_REF_READING,
2746                                    orig_sha1, &flag);
2747        if (flag & REF_ISSYMREF)
2748                return error("refname %s is a symbolic ref, renaming it is not supported",
2749                        oldrefname);
2750        if (!symref)
2751                return error("refname %s not found", oldrefname);
2752
2753        if (!rename_ref_available(oldrefname, newrefname))
2754                return 1;
2755
2756        if (log && rename(git_path("logs/%s", oldrefname), git_path(TMP_RENAMED_LOG)))
2757                return error("unable to move logfile logs/%s to "TMP_RENAMED_LOG": %s",
2758                        oldrefname, strerror(errno));
2759
2760        if (delete_ref(oldrefname, orig_sha1, REF_NODEREF)) {
2761                error("unable to delete old %s", oldrefname);
2762                goto rollback;
2763        }
2764
2765        if (!read_ref_full(newrefname, RESOLVE_REF_READING, sha1, NULL) &&
2766            delete_ref(newrefname, sha1, REF_NODEREF)) {
2767                if (errno==EISDIR) {
2768                        if (remove_empty_directories(git_path("%s", newrefname))) {
2769                                error("Directory not empty: %s", newrefname);
2770                                goto rollback;
2771                        }
2772                } else {
2773                        error("unable to delete existing %s", newrefname);
2774                        goto rollback;
2775                }
2776        }
2777
2778        if (log && rename_tmp_log(newrefname))
2779                goto rollback;
2780
2781        logmoved = log;
2782
2783        lock = lock_ref_sha1_basic(newrefname, NULL, NULL, 0, NULL);
2784        if (!lock) {
2785                error("unable to lock %s for update", newrefname);
2786                goto rollback;
2787        }
2788        lock->force_write = 1;
2789        hashcpy(lock->old_sha1, orig_sha1);
2790        if (write_ref_sha1(lock, orig_sha1, logmsg)) {
2791                error("unable to write current sha1 into %s", newrefname);
2792                goto rollback;
2793        }
2794
2795        return 0;
2796
2797 rollback:
2798        lock = lock_ref_sha1_basic(oldrefname, NULL, NULL, 0, NULL);
2799        if (!lock) {
2800                error("unable to lock %s for rollback", oldrefname);
2801                goto rollbacklog;
2802        }
2803
2804        lock->force_write = 1;
2805        flag = log_all_ref_updates;
2806        log_all_ref_updates = 0;
2807        if (write_ref_sha1(lock, orig_sha1, NULL))
2808                error("unable to write current sha1 into %s", oldrefname);
2809        log_all_ref_updates = flag;
2810
2811 rollbacklog:
2812        if (logmoved && rename(git_path("logs/%s", newrefname), git_path("logs/%s", oldrefname)))
2813                error("unable to restore logfile %s from %s: %s",
2814                        oldrefname, newrefname, strerror(errno));
2815        if (!logmoved && log &&
2816            rename(git_path(TMP_RENAMED_LOG), git_path("logs/%s", oldrefname)))
2817                error("unable to restore logfile %s from "TMP_RENAMED_LOG": %s",
2818                        oldrefname, strerror(errno));
2819
2820        return 1;
2821}
2822
2823int close_ref(struct ref_lock *lock)
2824{
2825        if (close_lock_file(lock->lk))
2826                return -1;
2827        lock->lock_fd = -1;
2828        return 0;
2829}
2830
2831int commit_ref(struct ref_lock *lock)
2832{
2833        if (commit_lock_file(lock->lk))
2834                return -1;
2835        lock->lock_fd = -1;
2836        return 0;
2837}
2838
2839void unlock_ref(struct ref_lock *lock)
2840{
2841        /* Do not free lock->lk -- atexit() still looks at them */
2842        if (lock->lk)
2843                rollback_lock_file(lock->lk);
2844        free(lock->ref_name);
2845        free(lock->orig_ref_name);
2846        free(lock);
2847}
2848
2849/*
2850 * copy the reflog message msg to buf, which has been allocated sufficiently
2851 * large, while cleaning up the whitespaces.  Especially, convert LF to space,
2852 * because reflog file is one line per entry.
2853 */
2854static int copy_msg(char *buf, const char *msg)
2855{
2856        char *cp = buf;
2857        char c;
2858        int wasspace = 1;
2859
2860        *cp++ = '\t';
2861        while ((c = *msg++)) {
2862                if (wasspace && isspace(c))
2863                        continue;
2864                wasspace = isspace(c);
2865                if (wasspace)
2866                        c = ' ';
2867                *cp++ = c;
2868        }
2869        while (buf < cp && isspace(cp[-1]))
2870                cp--;
2871        *cp++ = '\n';
2872        return cp - buf;
2873}
2874
2875/* This function must set a meaningful errno on failure */
2876int log_ref_setup(const char *refname, char *logfile, int bufsize)
2877{
2878        int logfd, oflags = O_APPEND | O_WRONLY;
2879
2880        git_snpath(logfile, bufsize, "logs/%s", refname);
2881        if (log_all_ref_updates &&
2882            (starts_with(refname, "refs/heads/") ||
2883             starts_with(refname, "refs/remotes/") ||
2884             starts_with(refname, "refs/notes/") ||
2885             !strcmp(refname, "HEAD"))) {
2886                if (safe_create_leading_directories(logfile) < 0) {
2887                        int save_errno = errno;
2888                        error("unable to create directory for %s", logfile);
2889                        errno = save_errno;
2890                        return -1;
2891                }
2892                oflags |= O_CREAT;
2893        }
2894
2895        logfd = open(logfile, oflags, 0666);
2896        if (logfd < 0) {
2897                if (!(oflags & O_CREAT) && errno == ENOENT)
2898                        return 0;
2899
2900                if ((oflags & O_CREAT) && errno == EISDIR) {
2901                        if (remove_empty_directories(logfile)) {
2902                                int save_errno = errno;
2903                                error("There are still logs under '%s'",
2904                                      logfile);
2905                                errno = save_errno;
2906                                return -1;
2907                        }
2908                        logfd = open(logfile, oflags, 0666);
2909                }
2910
2911                if (logfd < 0) {
2912                        int save_errno = errno;
2913                        error("Unable to append to %s: %s", logfile,
2914                              strerror(errno));
2915                        errno = save_errno;
2916                        return -1;
2917                }
2918        }
2919
2920        adjust_shared_perm(logfile);
2921        close(logfd);
2922        return 0;
2923}
2924
2925static int log_ref_write(const char *refname, const unsigned char *old_sha1,
2926                         const unsigned char *new_sha1, const char *msg)
2927{
2928        int logfd, result, written, oflags = O_APPEND | O_WRONLY;
2929        unsigned maxlen, len;
2930        int msglen;
2931        char log_file[PATH_MAX];
2932        char *logrec;
2933        const char *committer;
2934
2935        if (log_all_ref_updates < 0)
2936                log_all_ref_updates = !is_bare_repository();
2937
2938        result = log_ref_setup(refname, log_file, sizeof(log_file));
2939        if (result)
2940                return result;
2941
2942        logfd = open(log_file, oflags);
2943        if (logfd < 0)
2944                return 0;
2945        msglen = msg ? strlen(msg) : 0;
2946        committer = git_committer_info(0);
2947        maxlen = strlen(committer) + msglen + 100;
2948        logrec = xmalloc(maxlen);
2949        len = sprintf(logrec, "%s %s %s\n",
2950                      sha1_to_hex(old_sha1),
2951                      sha1_to_hex(new_sha1),
2952                      committer);
2953        if (msglen)
2954                len += copy_msg(logrec + len - 1, msg) - 1;
2955        written = len <= maxlen ? write_in_full(logfd, logrec, len) : -1;
2956        free(logrec);
2957        if (written != len) {
2958                int save_errno = errno;
2959                close(logfd);
2960                error("Unable to append to %s", log_file);
2961                errno = save_errno;
2962                return -1;
2963        }
2964        if (close(logfd)) {
2965                int save_errno = errno;
2966                error("Unable to append to %s", log_file);
2967                errno = save_errno;
2968                return -1;
2969        }
2970        return 0;
2971}
2972
2973int is_branch(const char *refname)
2974{
2975        return !strcmp(refname, "HEAD") || starts_with(refname, "refs/heads/");
2976}
2977
2978/*
2979 * Write sha1 into the ref specified by the lock. Make sure that errno
2980 * is sane on error.
2981 */
2982static int write_ref_sha1(struct ref_lock *lock,
2983        const unsigned char *sha1, const char *logmsg)
2984{
2985        static char term = '\n';
2986        struct object *o;
2987
2988        if (!lock) {
2989                errno = EINVAL;
2990                return -1;
2991        }
2992        if (!lock->force_write && !hashcmp(lock->old_sha1, sha1)) {
2993                unlock_ref(lock);
2994                return 0;
2995        }
2996        o = parse_object(sha1);
2997        if (!o) {
2998                error("Trying to write ref %s with nonexistent object %s",
2999                        lock->ref_name, sha1_to_hex(sha1));
3000                unlock_ref(lock);
3001                errno = EINVAL;
3002                return -1;
3003        }
3004        if (o->type != OBJ_COMMIT && is_branch(lock->ref_name)) {
3005                error("Trying to write non-commit object %s to branch %s",
3006                        sha1_to_hex(sha1), lock->ref_name);
3007                unlock_ref(lock);
3008                errno = EINVAL;
3009                return -1;
3010        }
3011        if (write_in_full(lock->lock_fd, sha1_to_hex(sha1), 40) != 40 ||
3012            write_in_full(lock->lock_fd, &term, 1) != 1 ||
3013            close_ref(lock) < 0) {
3014                int save_errno = errno;
3015                error("Couldn't write %s", lock->lk->filename.buf);
3016                unlock_ref(lock);
3017                errno = save_errno;
3018                return -1;
3019        }
3020        clear_loose_ref_cache(&ref_cache);
3021        if (log_ref_write(lock->ref_name, lock->old_sha1, sha1, logmsg) < 0 ||
3022            (strcmp(lock->ref_name, lock->orig_ref_name) &&
3023             log_ref_write(lock->orig_ref_name, lock->old_sha1, sha1, logmsg) < 0)) {
3024                unlock_ref(lock);
3025                return -1;
3026        }
3027        if (strcmp(lock->orig_ref_name, "HEAD") != 0) {
3028                /*
3029                 * Special hack: If a branch is updated directly and HEAD
3030                 * points to it (may happen on the remote side of a push
3031                 * for example) then logically the HEAD reflog should be
3032                 * updated too.
3033                 * A generic solution implies reverse symref information,
3034                 * but finding all symrefs pointing to the given branch
3035                 * would be rather costly for this rare event (the direct
3036                 * update of a branch) to be worth it.  So let's cheat and
3037                 * check with HEAD only which should cover 99% of all usage
3038                 * scenarios (even 100% of the default ones).
3039                 */
3040                unsigned char head_sha1[20];
3041                int head_flag;
3042                const char *head_ref;
3043                head_ref = resolve_ref_unsafe("HEAD", RESOLVE_REF_READING,
3044                                              head_sha1, &head_flag);
3045                if (head_ref && (head_flag & REF_ISSYMREF) &&
3046                    !strcmp(head_ref, lock->ref_name))
3047                        log_ref_write("HEAD", lock->old_sha1, sha1, logmsg);
3048        }
3049        if (commit_ref(lock)) {
3050                error("Couldn't set %s", lock->ref_name);
3051                unlock_ref(lock);
3052                return -1;
3053        }
3054        unlock_ref(lock);
3055        return 0;
3056}
3057
3058int create_symref(const char *ref_target, const char *refs_heads_master,
3059                  const char *logmsg)
3060{
3061        const char *lockpath;
3062        char ref[1000];
3063        int fd, len, written;
3064        char *git_HEAD = git_pathdup("%s", ref_target);
3065        unsigned char old_sha1[20], new_sha1[20];
3066
3067        if (logmsg && read_ref(ref_target, old_sha1))
3068                hashclr(old_sha1);
3069
3070        if (safe_create_leading_directories(git_HEAD) < 0)
3071                return error("unable to create directory for %s", git_HEAD);
3072
3073#ifndef NO_SYMLINK_HEAD
3074        if (prefer_symlink_refs) {
3075                unlink(git_HEAD);
3076                if (!symlink(refs_heads_master, git_HEAD))
3077                        goto done;
3078                fprintf(stderr, "no symlink - falling back to symbolic ref\n");
3079        }
3080#endif
3081
3082        len = snprintf(ref, sizeof(ref), "ref: %s\n", refs_heads_master);
3083        if (sizeof(ref) <= len) {
3084                error("refname too long: %s", refs_heads_master);
3085                goto error_free_return;
3086        }
3087        lockpath = mkpath("%s.lock", git_HEAD);
3088        fd = open(lockpath, O_CREAT | O_EXCL | O_WRONLY, 0666);
3089        if (fd < 0) {
3090                error("Unable to open %s for writing", lockpath);
3091                goto error_free_return;
3092        }
3093        written = write_in_full(fd, ref, len);
3094        if (close(fd) != 0 || written != len) {
3095                error("Unable to write to %s", lockpath);
3096                goto error_unlink_return;
3097        }
3098        if (rename(lockpath, git_HEAD) < 0) {
3099                error("Unable to create %s", git_HEAD);
3100                goto error_unlink_return;
3101        }
3102        if (adjust_shared_perm(git_HEAD)) {
3103                error("Unable to fix permissions on %s", lockpath);
3104        error_unlink_return:
3105                unlink_or_warn(lockpath);
3106        error_free_return:
3107                free(git_HEAD);
3108                return -1;
3109        }
3110
3111#ifndef NO_SYMLINK_HEAD
3112        done:
3113#endif
3114        if (logmsg && !read_ref(refs_heads_master, new_sha1))
3115                log_ref_write(ref_target, old_sha1, new_sha1, logmsg);
3116
3117        free(git_HEAD);
3118        return 0;
3119}
3120
3121struct read_ref_at_cb {
3122        const char *refname;
3123        unsigned long at_time;
3124        int cnt;
3125        int reccnt;
3126        unsigned char *sha1;
3127        int found_it;
3128
3129        unsigned char osha1[20];
3130        unsigned char nsha1[20];
3131        int tz;
3132        unsigned long date;
3133        char **msg;
3134        unsigned long *cutoff_time;
3135        int *cutoff_tz;
3136        int *cutoff_cnt;
3137};
3138
3139static int read_ref_at_ent(unsigned char *osha1, unsigned char *nsha1,
3140                const char *email, unsigned long timestamp, int tz,
3141                const char *message, void *cb_data)
3142{
3143        struct read_ref_at_cb *cb = cb_data;
3144
3145        cb->reccnt++;
3146        cb->tz = tz;
3147        cb->date = timestamp;
3148
3149        if (timestamp <= cb->at_time || cb->cnt == 0) {
3150                if (cb->msg)
3151                        *cb->msg = xstrdup(message);
3152                if (cb->cutoff_time)
3153                        *cb->cutoff_time = timestamp;
3154                if (cb->cutoff_tz)
3155                        *cb->cutoff_tz = tz;
3156                if (cb->cutoff_cnt)
3157                        *cb->cutoff_cnt = cb->reccnt - 1;
3158                /*
3159                 * we have not yet updated cb->[n|o]sha1 so they still
3160                 * hold the values for the previous record.
3161                 */
3162                if (!is_null_sha1(cb->osha1)) {
3163                        hashcpy(cb->sha1, nsha1);
3164                        if (hashcmp(cb->osha1, nsha1))
3165                                warning("Log for ref %s has gap after %s.",
3166                                        cb->refname, show_date(cb->date, cb->tz, DATE_RFC2822));
3167                }
3168                else if (cb->date == cb->at_time)
3169                        hashcpy(cb->sha1, nsha1);
3170                else if (hashcmp(nsha1, cb->sha1))
3171                        warning("Log for ref %s unexpectedly ended on %s.",
3172                                cb->refname, show_date(cb->date, cb->tz,
3173                                                   DATE_RFC2822));
3174                hashcpy(cb->osha1, osha1);
3175                hashcpy(cb->nsha1, nsha1);
3176                cb->found_it = 1;
3177                return 1;
3178        }
3179        hashcpy(cb->osha1, osha1);
3180        hashcpy(cb->nsha1, nsha1);
3181        if (cb->cnt > 0)
3182                cb->cnt--;
3183        return 0;
3184}
3185
3186static int read_ref_at_ent_oldest(unsigned char *osha1, unsigned char *nsha1,
3187                                  const char *email, unsigned long timestamp,
3188                                  int tz, const char *message, void *cb_data)
3189{
3190        struct read_ref_at_cb *cb = cb_data;
3191
3192        if (cb->msg)
3193                *cb->msg = xstrdup(message);
3194        if (cb->cutoff_time)
3195                *cb->cutoff_time = timestamp;
3196        if (cb->cutoff_tz)
3197                *cb->cutoff_tz = tz;
3198        if (cb->cutoff_cnt)
3199                *cb->cutoff_cnt = cb->reccnt;
3200        hashcpy(cb->sha1, osha1);
3201        if (is_null_sha1(cb->sha1))
3202                hashcpy(cb->sha1, nsha1);
3203        /* We just want the first entry */
3204        return 1;
3205}
3206
3207int read_ref_at(const char *refname, unsigned int flags, unsigned long at_time, int cnt,
3208                unsigned char *sha1, char **msg,
3209                unsigned long *cutoff_time, int *cutoff_tz, int *cutoff_cnt)
3210{
3211        struct read_ref_at_cb cb;
3212
3213        memset(&cb, 0, sizeof(cb));
3214        cb.refname = refname;
3215        cb.at_time = at_time;
3216        cb.cnt = cnt;
3217        cb.msg = msg;
3218        cb.cutoff_time = cutoff_time;
3219        cb.cutoff_tz = cutoff_tz;
3220        cb.cutoff_cnt = cutoff_cnt;
3221        cb.sha1 = sha1;
3222
3223        for_each_reflog_ent_reverse(refname, read_ref_at_ent, &cb);
3224
3225        if (!cb.reccnt) {
3226                if (flags & GET_SHA1_QUIETLY)
3227                        exit(128);
3228                else
3229                        die("Log for %s is empty.", refname);
3230        }
3231        if (cb.found_it)
3232                return 0;
3233
3234        for_each_reflog_ent(refname, read_ref_at_ent_oldest, &cb);
3235
3236        return 1;
3237}
3238
3239int reflog_exists(const char *refname)
3240{
3241        struct stat st;
3242
3243        return !lstat(git_path("logs/%s", refname), &st) &&
3244                S_ISREG(st.st_mode);
3245}
3246
3247int delete_reflog(const char *refname)
3248{
3249        return remove_path(git_path("logs/%s", refname));
3250}
3251
3252static int show_one_reflog_ent(struct strbuf *sb, each_reflog_ent_fn fn, void *cb_data)
3253{
3254        unsigned char osha1[20], nsha1[20];
3255        char *email_end, *message;
3256        unsigned long timestamp;
3257        int tz;
3258
3259        /* old SP new SP name <email> SP time TAB msg LF */
3260        if (sb->len < 83 || sb->buf[sb->len - 1] != '\n' ||
3261            get_sha1_hex(sb->buf, osha1) || sb->buf[40] != ' ' ||
3262            get_sha1_hex(sb->buf + 41, nsha1) || sb->buf[81] != ' ' ||
3263            !(email_end = strchr(sb->buf + 82, '>')) ||
3264            email_end[1] != ' ' ||
3265            !(timestamp = strtoul(email_end + 2, &message, 10)) ||
3266            !message || message[0] != ' ' ||
3267            (message[1] != '+' && message[1] != '-') ||
3268            !isdigit(message[2]) || !isdigit(message[3]) ||
3269            !isdigit(message[4]) || !isdigit(message[5]))
3270                return 0; /* corrupt? */
3271        email_end[1] = '\0';
3272        tz = strtol(message + 1, NULL, 10);
3273        if (message[6] != '\t')
3274                message += 6;
3275        else
3276                message += 7;
3277        return fn(osha1, nsha1, sb->buf + 82, timestamp, tz, message, cb_data);
3278}
3279
3280static char *find_beginning_of_line(char *bob, char *scan)
3281{
3282        while (bob < scan && *(--scan) != '\n')
3283                ; /* keep scanning backwards */
3284        /*
3285         * Return either beginning of the buffer, or LF at the end of
3286         * the previous line.
3287         */
3288        return scan;
3289}
3290
3291int for_each_reflog_ent_reverse(const char *refname, each_reflog_ent_fn fn, void *cb_data)
3292{
3293        struct strbuf sb = STRBUF_INIT;
3294        FILE *logfp;
3295        long pos;
3296        int ret = 0, at_tail = 1;
3297
3298        logfp = fopen(git_path("logs/%s", refname), "r");
3299        if (!logfp)
3300                return -1;
3301
3302        /* Jump to the end */
3303        if (fseek(logfp, 0, SEEK_END) < 0)
3304                return error("cannot seek back reflog for %s: %s",
3305                             refname, strerror(errno));
3306        pos = ftell(logfp);
3307        while (!ret && 0 < pos) {
3308                int cnt;
3309                size_t nread;
3310                char buf[BUFSIZ];
3311                char *endp, *scanp;
3312
3313                /* Fill next block from the end */
3314                cnt = (sizeof(buf) < pos) ? sizeof(buf) : pos;
3315                if (fseek(logfp, pos - cnt, SEEK_SET))
3316                        return error("cannot seek back reflog for %s: %s",
3317                                     refname, strerror(errno));
3318                nread = fread(buf, cnt, 1, logfp);
3319                if (nread != 1)
3320                        return error("cannot read %d bytes from reflog for %s: %s",
3321                                     cnt, refname, strerror(errno));
3322                pos -= cnt;
3323
3324                scanp = endp = buf + cnt;
3325                if (at_tail && scanp[-1] == '\n')
3326                        /* Looking at the final LF at the end of the file */
3327                        scanp--;
3328                at_tail = 0;
3329
3330                while (buf < scanp) {
3331                        /*
3332                         * terminating LF of the previous line, or the beginning
3333                         * of the buffer.
3334                         */
3335                        char *bp;
3336
3337                        bp = find_beginning_of_line(buf, scanp);
3338
3339                        if (*bp != '\n') {
3340                                strbuf_splice(&sb, 0, 0, buf, endp - buf);
3341                                if (pos)
3342                                        break; /* need to fill another block */
3343                                scanp = buf - 1; /* leave loop */
3344                        } else {
3345                                /*
3346                                 * (bp + 1) thru endp is the beginning of the
3347                                 * current line we have in sb
3348                                 */
3349                                strbuf_splice(&sb, 0, 0, bp + 1, endp - (bp + 1));
3350                                scanp = bp;
3351                                endp = bp + 1;
3352                        }
3353                        ret = show_one_reflog_ent(&sb, fn, cb_data);
3354                        strbuf_reset(&sb);
3355                        if (ret)
3356                                break;
3357                }
3358
3359        }
3360        if (!ret && sb.len)
3361                ret = show_one_reflog_ent(&sb, fn, cb_data);
3362
3363        fclose(logfp);
3364        strbuf_release(&sb);
3365        return ret;
3366}
3367
3368int for_each_reflog_ent(const char *refname, each_reflog_ent_fn fn, void *cb_data)
3369{
3370        FILE *logfp;
3371        struct strbuf sb = STRBUF_INIT;
3372        int ret = 0;
3373
3374        logfp = fopen(git_path("logs/%s", refname), "r");
3375        if (!logfp)
3376                return -1;
3377
3378        while (!ret && !strbuf_getwholeline(&sb, logfp, '\n'))
3379                ret = show_one_reflog_ent(&sb, fn, cb_data);
3380        fclose(logfp);
3381        strbuf_release(&sb);
3382        return ret;
3383}
3384/*
3385 * Call fn for each reflog in the namespace indicated by name.  name
3386 * must be empty or end with '/'.  Name will be used as a scratch
3387 * space, but its contents will be restored before return.
3388 */
3389static int do_for_each_reflog(struct strbuf *name, each_ref_fn fn, void *cb_data)
3390{
3391        DIR *d = opendir(git_path("logs/%s", name->buf));
3392        int retval = 0;
3393        struct dirent *de;
3394        int oldlen = name->len;
3395
3396        if (!d)
3397                return name->len ? errno : 0;
3398
3399        while ((de = readdir(d)) != NULL) {
3400                struct stat st;
3401
3402                if (de->d_name[0] == '.')
3403                        continue;
3404                if (ends_with(de->d_name, ".lock"))
3405                        continue;
3406                strbuf_addstr(name, de->d_name);
3407                if (stat(git_path("logs/%s", name->buf), &st) < 0) {
3408                        ; /* silently ignore */
3409                } else {
3410                        if (S_ISDIR(st.st_mode)) {
3411                                strbuf_addch(name, '/');
3412                                retval = do_for_each_reflog(name, fn, cb_data);
3413                        } else {
3414                                unsigned char sha1[20];
3415                                if (read_ref_full(name->buf, 0, sha1, NULL))
3416                                        retval = error("bad ref for %s", name->buf);
3417                                else
3418                                        retval = fn(name->buf, sha1, 0, cb_data);
3419                        }
3420                        if (retval)
3421                                break;
3422                }
3423                strbuf_setlen(name, oldlen);
3424        }
3425        closedir(d);
3426        return retval;
3427}
3428
3429int for_each_reflog(each_ref_fn fn, void *cb_data)
3430{
3431        int retval;
3432        struct strbuf name;
3433        strbuf_init(&name, PATH_MAX);
3434        retval = do_for_each_reflog(&name, fn, cb_data);
3435        strbuf_release(&name);
3436        return retval;
3437}
3438
3439/**
3440 * Information needed for a single ref update.  Set new_sha1 to the
3441 * new value or to zero to delete the ref.  To check the old value
3442 * while locking the ref, set have_old to 1 and set old_sha1 to the
3443 * value or to zero to ensure the ref does not exist before update.
3444 */
3445struct ref_update {
3446        unsigned char new_sha1[20];
3447        unsigned char old_sha1[20];
3448        int flags; /* REF_NODEREF? */
3449        int have_old; /* 1 if old_sha1 is valid, 0 otherwise */
3450        struct ref_lock *lock;
3451        int type;
3452        char *msg;
3453        const char refname[FLEX_ARRAY];
3454};
3455
3456/*
3457 * Transaction states.
3458 * OPEN:   The transaction is in a valid state and can accept new updates.
3459 *         An OPEN transaction can be committed.
3460 * CLOSED: A closed transaction is no longer active and no other operations
3461 *         than free can be used on it in this state.
3462 *         A transaction can either become closed by successfully committing
3463 *         an active transaction or if there is a failure while building
3464 *         the transaction thus rendering it failed/inactive.
3465 */
3466enum ref_transaction_state {
3467        REF_TRANSACTION_OPEN   = 0,
3468        REF_TRANSACTION_CLOSED = 1
3469};
3470
3471/*
3472 * Data structure for holding a reference transaction, which can
3473 * consist of checks and updates to multiple references, carried out
3474 * as atomically as possible.  This structure is opaque to callers.
3475 */
3476struct ref_transaction {
3477        struct ref_update **updates;
3478        size_t alloc;
3479        size_t nr;
3480        enum ref_transaction_state state;
3481};
3482
3483struct ref_transaction *ref_transaction_begin(struct strbuf *err)
3484{
3485        return xcalloc(1, sizeof(struct ref_transaction));
3486}
3487
3488void ref_transaction_free(struct ref_transaction *transaction)
3489{
3490        int i;
3491
3492        if (!transaction)
3493                return;
3494
3495        for (i = 0; i < transaction->nr; i++) {
3496                free(transaction->updates[i]->msg);
3497                free(transaction->updates[i]);
3498        }
3499        free(transaction->updates);
3500        free(transaction);
3501}
3502
3503static struct ref_update *add_update(struct ref_transaction *transaction,
3504                                     const char *refname)
3505{
3506        size_t len = strlen(refname);
3507        struct ref_update *update = xcalloc(1, sizeof(*update) + len + 1);
3508
3509        strcpy((char *)update->refname, refname);
3510        ALLOC_GROW(transaction->updates, transaction->nr + 1, transaction->alloc);
3511        transaction->updates[transaction->nr++] = update;
3512        return update;
3513}
3514
3515int ref_transaction_update(struct ref_transaction *transaction,
3516                           const char *refname,
3517                           const unsigned char *new_sha1,
3518                           const unsigned char *old_sha1,
3519                           int flags, int have_old, const char *msg,
3520                           struct strbuf *err)
3521{
3522        struct ref_update *update;
3523
3524        if (transaction->state != REF_TRANSACTION_OPEN)
3525                die("BUG: update called for transaction that is not open");
3526
3527        if (have_old && !old_sha1)
3528                die("BUG: have_old is true but old_sha1 is NULL");
3529
3530        update = add_update(transaction, refname);
3531        hashcpy(update->new_sha1, new_sha1);
3532        update->flags = flags;
3533        update->have_old = have_old;
3534        if (have_old)
3535                hashcpy(update->old_sha1, old_sha1);
3536        if (msg)
3537                update->msg = xstrdup(msg);
3538        return 0;
3539}
3540
3541int ref_transaction_create(struct ref_transaction *transaction,
3542                           const char *refname,
3543                           const unsigned char *new_sha1,
3544                           int flags, const char *msg,
3545                           struct strbuf *err)
3546{
3547        struct ref_update *update;
3548
3549        if (transaction->state != REF_TRANSACTION_OPEN)
3550                die("BUG: create called for transaction that is not open");
3551
3552        if (!new_sha1 || is_null_sha1(new_sha1))
3553                die("BUG: create ref with null new_sha1");
3554
3555        update = add_update(transaction, refname);
3556
3557        hashcpy(update->new_sha1, new_sha1);
3558        hashclr(update->old_sha1);
3559        update->flags = flags;
3560        update->have_old = 1;
3561        if (msg)
3562                update->msg = xstrdup(msg);
3563        return 0;
3564}
3565
3566int ref_transaction_delete(struct ref_transaction *transaction,
3567                           const char *refname,
3568                           const unsigned char *old_sha1,
3569                           int flags, int have_old, const char *msg,
3570                           struct strbuf *err)
3571{
3572        struct ref_update *update;
3573
3574        if (transaction->state != REF_TRANSACTION_OPEN)
3575                die("BUG: delete called for transaction that is not open");
3576
3577        if (have_old && !old_sha1)
3578                die("BUG: have_old is true but old_sha1 is NULL");
3579
3580        update = add_update(transaction, refname);
3581        update->flags = flags;
3582        update->have_old = have_old;
3583        if (have_old) {
3584                assert(!is_null_sha1(old_sha1));
3585                hashcpy(update->old_sha1, old_sha1);
3586        }
3587        if (msg)
3588                update->msg = xstrdup(msg);
3589        return 0;
3590}
3591
3592int update_ref(const char *action, const char *refname,
3593               const unsigned char *sha1, const unsigned char *oldval,
3594               int flags, enum action_on_err onerr)
3595{
3596        struct ref_transaction *t;
3597        struct strbuf err = STRBUF_INIT;
3598
3599        t = ref_transaction_begin(&err);
3600        if (!t ||
3601            ref_transaction_update(t, refname, sha1, oldval, flags,
3602                                   !!oldval, action, &err) ||
3603            ref_transaction_commit(t, &err)) {
3604                const char *str = "update_ref failed for ref '%s': %s";
3605
3606                ref_transaction_free(t);
3607                switch (onerr) {
3608                case UPDATE_REFS_MSG_ON_ERR:
3609                        error(str, refname, err.buf);
3610                        break;
3611                case UPDATE_REFS_DIE_ON_ERR:
3612                        die(str, refname, err.buf);
3613                        break;
3614                case UPDATE_REFS_QUIET_ON_ERR:
3615                        break;
3616                }
3617                strbuf_release(&err);
3618                return 1;
3619        }
3620        strbuf_release(&err);
3621        ref_transaction_free(t);
3622        return 0;
3623}
3624
3625static int ref_update_compare(const void *r1, const void *r2)
3626{
3627        const struct ref_update * const *u1 = r1;
3628        const struct ref_update * const *u2 = r2;
3629        return strcmp((*u1)->refname, (*u2)->refname);
3630}
3631
3632static int ref_update_reject_duplicates(struct ref_update **updates, int n,
3633                                        struct strbuf *err)
3634{
3635        int i;
3636        for (i = 1; i < n; i++)
3637                if (!strcmp(updates[i - 1]->refname, updates[i]->refname)) {
3638                        const char *str =
3639                                "Multiple updates for ref '%s' not allowed.";
3640                        if (err)
3641                                strbuf_addf(err, str, updates[i]->refname);
3642
3643                        return 1;
3644                }
3645        return 0;
3646}
3647
3648int ref_transaction_commit(struct ref_transaction *transaction,
3649                           struct strbuf *err)
3650{
3651        int ret = 0, delnum = 0, i;
3652        const char **delnames;
3653        int n = transaction->nr;
3654        struct ref_update **updates = transaction->updates;
3655
3656        if (transaction->state != REF_TRANSACTION_OPEN)
3657                die("BUG: commit called for transaction that is not open");
3658
3659        if (!n) {
3660                transaction->state = REF_TRANSACTION_CLOSED;
3661                return 0;
3662        }
3663
3664        /* Allocate work space */
3665        delnames = xmalloc(sizeof(*delnames) * n);
3666
3667        /* Copy, sort, and reject duplicate refs */
3668        qsort(updates, n, sizeof(*updates), ref_update_compare);
3669        if (ref_update_reject_duplicates(updates, n, err)) {
3670                ret = TRANSACTION_GENERIC_ERROR;
3671                goto cleanup;
3672        }
3673
3674        /* Acquire all locks while verifying old values */
3675        for (i = 0; i < n; i++) {
3676                struct ref_update *update = updates[i];
3677                int flags = update->flags;
3678
3679                if (is_null_sha1(update->new_sha1))
3680                        flags |= REF_DELETING;
3681                update->lock = lock_ref_sha1_basic(update->refname,
3682                                                   (update->have_old ?
3683                                                    update->old_sha1 :
3684                                                    NULL),
3685                                                   NULL,
3686                                                   flags,
3687                                                   &update->type);
3688                if (!update->lock) {
3689                        ret = (errno == ENOTDIR)
3690                                ? TRANSACTION_NAME_CONFLICT
3691                                : TRANSACTION_GENERIC_ERROR;
3692                        if (err)
3693                                strbuf_addf(err, "Cannot lock the ref '%s'.",
3694                                            update->refname);
3695                        goto cleanup;
3696                }
3697        }
3698
3699        /* Perform updates first so live commits remain referenced */
3700        for (i = 0; i < n; i++) {
3701                struct ref_update *update = updates[i];
3702
3703                if (!is_null_sha1(update->new_sha1)) {
3704                        if (write_ref_sha1(update->lock, update->new_sha1,
3705                                           update->msg)) {
3706                                update->lock = NULL; /* freed by write_ref_sha1 */
3707                                if (err)
3708                                        strbuf_addf(err, "Cannot update the ref '%s'.",
3709                                                    update->refname);
3710                                ret = TRANSACTION_GENERIC_ERROR;
3711                                goto cleanup;
3712                        }
3713                        update->lock = NULL; /* freed by write_ref_sha1 */
3714                }
3715        }
3716
3717        /* Perform deletes now that updates are safely completed */
3718        for (i = 0; i < n; i++) {
3719                struct ref_update *update = updates[i];
3720
3721                if (update->lock) {
3722                        if (delete_ref_loose(update->lock, update->type, err))
3723                                ret = TRANSACTION_GENERIC_ERROR;
3724
3725                        if (!(update->flags & REF_ISPRUNING))
3726                                delnames[delnum++] = update->lock->ref_name;
3727                }
3728        }
3729
3730        if (repack_without_refs(delnames, delnum, err))
3731                ret = TRANSACTION_GENERIC_ERROR;
3732        for (i = 0; i < delnum; i++)
3733                unlink_or_warn(git_path("logs/%s", delnames[i]));
3734        clear_loose_ref_cache(&ref_cache);
3735
3736cleanup:
3737        transaction->state = REF_TRANSACTION_CLOSED;
3738
3739        for (i = 0; i < n; i++)
3740                if (updates[i]->lock)
3741                        unlock_ref(updates[i]->lock);
3742        free(delnames);
3743        return ret;
3744}
3745
3746char *shorten_unambiguous_ref(const char *refname, int strict)
3747{
3748        int i;
3749        static char **scanf_fmts;
3750        static int nr_rules;
3751        char *short_name;
3752
3753        if (!nr_rules) {
3754                /*
3755                 * Pre-generate scanf formats from ref_rev_parse_rules[].
3756                 * Generate a format suitable for scanf from a
3757                 * ref_rev_parse_rules rule by interpolating "%s" at the
3758                 * location of the "%.*s".
3759                 */
3760                size_t total_len = 0;
3761                size_t offset = 0;
3762
3763                /* the rule list is NULL terminated, count them first */
3764                for (nr_rules = 0; ref_rev_parse_rules[nr_rules]; nr_rules++)
3765                        /* -2 for strlen("%.*s") - strlen("%s"); +1 for NUL */
3766                        total_len += strlen(ref_rev_parse_rules[nr_rules]) - 2 + 1;
3767
3768                scanf_fmts = xmalloc(nr_rules * sizeof(char *) + total_len);
3769
3770                offset = 0;
3771                for (i = 0; i < nr_rules; i++) {
3772                        assert(offset < total_len);
3773                        scanf_fmts[i] = (char *)&scanf_fmts[nr_rules] + offset;
3774                        offset += snprintf(scanf_fmts[i], total_len - offset,
3775                                           ref_rev_parse_rules[i], 2, "%s") + 1;
3776                }
3777        }
3778
3779        /* bail out if there are no rules */
3780        if (!nr_rules)
3781                return xstrdup(refname);
3782
3783        /* buffer for scanf result, at most refname must fit */
3784        short_name = xstrdup(refname);
3785
3786        /* skip first rule, it will always match */
3787        for (i = nr_rules - 1; i > 0 ; --i) {
3788                int j;
3789                int rules_to_fail = i;
3790                int short_name_len;
3791
3792                if (1 != sscanf(refname, scanf_fmts[i], short_name))
3793                        continue;
3794
3795                short_name_len = strlen(short_name);
3796
3797                /*
3798                 * in strict mode, all (except the matched one) rules
3799                 * must fail to resolve to a valid non-ambiguous ref
3800                 */
3801                if (strict)
3802                        rules_to_fail = nr_rules;
3803
3804                /*
3805                 * check if the short name resolves to a valid ref,
3806                 * but use only rules prior to the matched one
3807                 */
3808                for (j = 0; j < rules_to_fail; j++) {
3809                        const char *rule = ref_rev_parse_rules[j];
3810                        char refname[PATH_MAX];
3811
3812                        /* skip matched rule */
3813                        if (i == j)
3814                                continue;
3815
3816                        /*
3817                         * the short name is ambiguous, if it resolves
3818                         * (with this previous rule) to a valid ref
3819                         * read_ref() returns 0 on success
3820                         */
3821                        mksnpath(refname, sizeof(refname),
3822                                 rule, short_name_len, short_name);
3823                        if (ref_exists(refname))
3824                                break;
3825                }
3826
3827                /*
3828                 * short name is non-ambiguous if all previous rules
3829                 * haven't resolved to a valid ref
3830                 */
3831                if (j == rules_to_fail)
3832                        return short_name;
3833        }
3834
3835        free(short_name);
3836        return xstrdup(refname);
3837}
3838
3839static struct string_list *hide_refs;
3840
3841int parse_hide_refs_config(const char *var, const char *value, const char *section)
3842{
3843        if (!strcmp("transfer.hiderefs", var) ||
3844            /* NEEDSWORK: use parse_config_key() once both are merged */
3845            (starts_with(var, section) && var[strlen(section)] == '.' &&
3846             !strcmp(var + strlen(section), ".hiderefs"))) {
3847                char *ref;
3848                int len;
3849
3850                if (!value)
3851                        return config_error_nonbool(var);
3852                ref = xstrdup(value);
3853                len = strlen(ref);
3854                while (len && ref[len - 1] == '/')
3855                        ref[--len] = '\0';
3856                if (!hide_refs) {
3857                        hide_refs = xcalloc(1, sizeof(*hide_refs));
3858                        hide_refs->strdup_strings = 1;
3859                }
3860                string_list_append(hide_refs, ref);
3861        }
3862        return 0;
3863}
3864
3865int ref_is_hidden(const char *refname)
3866{
3867        struct string_list_item *item;
3868
3869        if (!hide_refs)
3870                return 0;
3871        for_each_string_list_item(item, hide_refs) {
3872                int len;
3873                if (!starts_with(refname, item->string))
3874                        continue;
3875                len = strlen(item->string);
3876                if (!refname[len] || refname[len] == '/')
3877                        return 1;
3878        }
3879        return 0;
3880}