fd6768429d1932506caf85c8b70cab533296fb27
   1#include "cache.h"
   2#include "refs.h"
   3#include "object.h"
   4#include "tag.h"
   5#include "dir.h"
   6#include "string-list.h"
   7
   8/*
   9 * How to handle various characters in refnames:
  10 * 0: An acceptable character for refs
  11 * 1: End-of-component
  12 * 2: ., look for a preceding . to reject .. in refs
  13 * 3: {, look for a preceding @ to reject @{ in refs
  14 * 4: A bad character: ASCII control characters, "~", "^", ":" or SP
  15 */
  16static unsigned char refname_disposition[256] = {
  17        1, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
  18        4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
  19        4, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4, 0, 0, 0, 2, 1,
  20        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4, 0, 0, 0, 0, 4,
  21        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  22        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4, 4, 0, 4, 0,
  23        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  24        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 3, 0, 0, 4, 4
  25};
  26
  27/*
  28 * Try to read one refname component from the front of refname.
  29 * Return the length of the component found, or -1 if the component is
  30 * not legal.  It is legal if it is something reasonable to have under
  31 * ".git/refs/"; We do not like it if:
  32 *
  33 * - any path component of it begins with ".", or
  34 * - it has double dots "..", or
  35 * - it has ASCII control character, "~", "^", ":" or SP, anywhere, or
  36 * - it ends with a "/".
  37 * - it ends with ".lock"
  38 * - it contains a "\" (backslash)
  39 */
  40static int check_refname_component(const char *refname, int flags)
  41{
  42        const char *cp;
  43        char last = '\0';
  44
  45        for (cp = refname; ; cp++) {
  46                int ch = *cp & 255;
  47                unsigned char disp = refname_disposition[ch];
  48                switch (disp) {
  49                case 1:
  50                        goto out;
  51                case 2:
  52                        if (last == '.')
  53                                return -1; /* Refname contains "..". */
  54                        break;
  55                case 3:
  56                        if (last == '@')
  57                                return -1; /* Refname contains "@{". */
  58                        break;
  59                case 4:
  60                        return -1;
  61                }
  62                last = ch;
  63        }
  64out:
  65        if (cp == refname)
  66                return 0; /* Component has zero length. */
  67        if (refname[0] == '.') {
  68                if (!(flags & REFNAME_DOT_COMPONENT))
  69                        return -1; /* Component starts with '.'. */
  70                /*
  71                 * Even if leading dots are allowed, don't allow "."
  72                 * as a component (".." is prevented by a rule above).
  73                 */
  74                if (refname[1] == '\0')
  75                        return -1; /* Component equals ".". */
  76        }
  77        if (cp - refname >= 5 && !memcmp(cp - 5, ".lock", 5))
  78                return -1; /* Refname ends with ".lock". */
  79        return cp - refname;
  80}
  81
  82int check_refname_format(const char *refname, int flags)
  83{
  84        int component_len, component_count = 0;
  85
  86        if (!strcmp(refname, "@"))
  87                /* Refname is a single character '@'. */
  88                return -1;
  89
  90        while (1) {
  91                /* We are at the start of a path component. */
  92                component_len = check_refname_component(refname, flags);
  93                if (component_len <= 0) {
  94                        if ((flags & REFNAME_REFSPEC_PATTERN) &&
  95                                        refname[0] == '*' &&
  96                                        (refname[1] == '\0' || refname[1] == '/')) {
  97                                /* Accept one wildcard as a full refname component. */
  98                                flags &= ~REFNAME_REFSPEC_PATTERN;
  99                                component_len = 1;
 100                        } else {
 101                                return -1;
 102                        }
 103                }
 104                component_count++;
 105                if (refname[component_len] == '\0')
 106                        break;
 107                /* Skip to next component. */
 108                refname += component_len + 1;
 109        }
 110
 111        if (refname[component_len - 1] == '.')
 112                return -1; /* Refname ends with '.'. */
 113        if (!(flags & REFNAME_ALLOW_ONELEVEL) && component_count < 2)
 114                return -1; /* Refname has only one component. */
 115        return 0;
 116}
 117
 118struct ref_entry;
 119
 120/*
 121 * Information used (along with the information in ref_entry) to
 122 * describe a single cached reference.  This data structure only
 123 * occurs embedded in a union in struct ref_entry, and only when
 124 * (ref_entry->flag & REF_DIR) is zero.
 125 */
 126struct ref_value {
 127        /*
 128         * The name of the object to which this reference resolves
 129         * (which may be a tag object).  If REF_ISBROKEN, this is
 130         * null.  If REF_ISSYMREF, then this is the name of the object
 131         * referred to by the last reference in the symlink chain.
 132         */
 133        unsigned char sha1[20];
 134
 135        /*
 136         * If REF_KNOWS_PEELED, then this field holds the peeled value
 137         * of this reference, or null if the reference is known not to
 138         * be peelable.  See the documentation for peel_ref() for an
 139         * exact definition of "peelable".
 140         */
 141        unsigned char peeled[20];
 142};
 143
 144struct ref_cache;
 145
 146/*
 147 * Information used (along with the information in ref_entry) to
 148 * describe a level in the hierarchy of references.  This data
 149 * structure only occurs embedded in a union in struct ref_entry, and
 150 * only when (ref_entry.flag & REF_DIR) is set.  In that case,
 151 * (ref_entry.flag & REF_INCOMPLETE) determines whether the references
 152 * in the directory have already been read:
 153 *
 154 *     (ref_entry.flag & REF_INCOMPLETE) unset -- a directory of loose
 155 *         or packed references, already read.
 156 *
 157 *     (ref_entry.flag & REF_INCOMPLETE) set -- a directory of loose
 158 *         references that hasn't been read yet (nor has any of its
 159 *         subdirectories).
 160 *
 161 * Entries within a directory are stored within a growable array of
 162 * pointers to ref_entries (entries, nr, alloc).  Entries 0 <= i <
 163 * sorted are sorted by their component name in strcmp() order and the
 164 * remaining entries are unsorted.
 165 *
 166 * Loose references are read lazily, one directory at a time.  When a
 167 * directory of loose references is read, then all of the references
 168 * in that directory are stored, and REF_INCOMPLETE stubs are created
 169 * for any subdirectories, but the subdirectories themselves are not
 170 * read.  The reading is triggered by get_ref_dir().
 171 */
 172struct ref_dir {
 173        int nr, alloc;
 174
 175        /*
 176         * Entries with index 0 <= i < sorted are sorted by name.  New
 177         * entries are appended to the list unsorted, and are sorted
 178         * only when required; thus we avoid the need to sort the list
 179         * after the addition of every reference.
 180         */
 181        int sorted;
 182
 183        /* A pointer to the ref_cache that contains this ref_dir. */
 184        struct ref_cache *ref_cache;
 185
 186        struct ref_entry **entries;
 187};
 188
 189/*
 190 * Bit values for ref_entry::flag.  REF_ISSYMREF=0x01,
 191 * REF_ISPACKED=0x02, and REF_ISBROKEN=0x04 are public values; see
 192 * refs.h.
 193 */
 194
 195/*
 196 * The field ref_entry->u.value.peeled of this value entry contains
 197 * the correct peeled value for the reference, which might be
 198 * null_sha1 if the reference is not a tag or if it is broken.
 199 */
 200#define REF_KNOWS_PEELED 0x08
 201
 202/* ref_entry represents a directory of references */
 203#define REF_DIR 0x10
 204
 205/*
 206 * Entry has not yet been read from disk (used only for REF_DIR
 207 * entries representing loose references)
 208 */
 209#define REF_INCOMPLETE 0x20
 210
 211/*
 212 * A ref_entry represents either a reference or a "subdirectory" of
 213 * references.
 214 *
 215 * Each directory in the reference namespace is represented by a
 216 * ref_entry with (flags & REF_DIR) set and containing a subdir member
 217 * that holds the entries in that directory that have been read so
 218 * far.  If (flags & REF_INCOMPLETE) is set, then the directory and
 219 * its subdirectories haven't been read yet.  REF_INCOMPLETE is only
 220 * used for loose reference directories.
 221 *
 222 * References are represented by a ref_entry with (flags & REF_DIR)
 223 * unset and a value member that describes the reference's value.  The
 224 * flag member is at the ref_entry level, but it is also needed to
 225 * interpret the contents of the value field (in other words, a
 226 * ref_value object is not very much use without the enclosing
 227 * ref_entry).
 228 *
 229 * Reference names cannot end with slash and directories' names are
 230 * always stored with a trailing slash (except for the top-level
 231 * directory, which is always denoted by "").  This has two nice
 232 * consequences: (1) when the entries in each subdir are sorted
 233 * lexicographically by name (as they usually are), the references in
 234 * a whole tree can be generated in lexicographic order by traversing
 235 * the tree in left-to-right, depth-first order; (2) the names of
 236 * references and subdirectories cannot conflict, and therefore the
 237 * presence of an empty subdirectory does not block the creation of a
 238 * similarly-named reference.  (The fact that reference names with the
 239 * same leading components can conflict *with each other* is a
 240 * separate issue that is regulated by is_refname_available().)
 241 *
 242 * Please note that the name field contains the fully-qualified
 243 * reference (or subdirectory) name.  Space could be saved by only
 244 * storing the relative names.  But that would require the full names
 245 * to be generated on the fly when iterating in do_for_each_ref(), and
 246 * would break callback functions, who have always been able to assume
 247 * that the name strings that they are passed will not be freed during
 248 * the iteration.
 249 */
 250struct ref_entry {
 251        unsigned char flag; /* ISSYMREF? ISPACKED? */
 252        union {
 253                struct ref_value value; /* if not (flags&REF_DIR) */
 254                struct ref_dir subdir; /* if (flags&REF_DIR) */
 255        } u;
 256        /*
 257         * The full name of the reference (e.g., "refs/heads/master")
 258         * or the full name of the directory with a trailing slash
 259         * (e.g., "refs/heads/"):
 260         */
 261        char name[FLEX_ARRAY];
 262};
 263
 264static void read_loose_refs(const char *dirname, struct ref_dir *dir);
 265
 266static struct ref_dir *get_ref_dir(struct ref_entry *entry)
 267{
 268        struct ref_dir *dir;
 269        assert(entry->flag & REF_DIR);
 270        dir = &entry->u.subdir;
 271        if (entry->flag & REF_INCOMPLETE) {
 272                read_loose_refs(entry->name, dir);
 273                entry->flag &= ~REF_INCOMPLETE;
 274        }
 275        return dir;
 276}
 277
 278static struct ref_entry *create_ref_entry(const char *refname,
 279                                          const unsigned char *sha1, int flag,
 280                                          int check_name)
 281{
 282        int len;
 283        struct ref_entry *ref;
 284
 285        if (check_name &&
 286            check_refname_format(refname, REFNAME_ALLOW_ONELEVEL|REFNAME_DOT_COMPONENT))
 287                die("Reference has invalid format: '%s'", refname);
 288        len = strlen(refname) + 1;
 289        ref = xmalloc(sizeof(struct ref_entry) + len);
 290        hashcpy(ref->u.value.sha1, sha1);
 291        hashclr(ref->u.value.peeled);
 292        memcpy(ref->name, refname, len);
 293        ref->flag = flag;
 294        return ref;
 295}
 296
 297static void clear_ref_dir(struct ref_dir *dir);
 298
 299static void free_ref_entry(struct ref_entry *entry)
 300{
 301        if (entry->flag & REF_DIR) {
 302                /*
 303                 * Do not use get_ref_dir() here, as that might
 304                 * trigger the reading of loose refs.
 305                 */
 306                clear_ref_dir(&entry->u.subdir);
 307        }
 308        free(entry);
 309}
 310
 311/*
 312 * Add a ref_entry to the end of dir (unsorted).  Entry is always
 313 * stored directly in dir; no recursion into subdirectories is
 314 * done.
 315 */
 316static void add_entry_to_dir(struct ref_dir *dir, struct ref_entry *entry)
 317{
 318        ALLOC_GROW(dir->entries, dir->nr + 1, dir->alloc);
 319        dir->entries[dir->nr++] = entry;
 320        /* optimize for the case that entries are added in order */
 321        if (dir->nr == 1 ||
 322            (dir->nr == dir->sorted + 1 &&
 323             strcmp(dir->entries[dir->nr - 2]->name,
 324                    dir->entries[dir->nr - 1]->name) < 0))
 325                dir->sorted = dir->nr;
 326}
 327
 328/*
 329 * Clear and free all entries in dir, recursively.
 330 */
 331static void clear_ref_dir(struct ref_dir *dir)
 332{
 333        int i;
 334        for (i = 0; i < dir->nr; i++)
 335                free_ref_entry(dir->entries[i]);
 336        free(dir->entries);
 337        dir->sorted = dir->nr = dir->alloc = 0;
 338        dir->entries = NULL;
 339}
 340
 341/*
 342 * Create a struct ref_entry object for the specified dirname.
 343 * dirname is the name of the directory with a trailing slash (e.g.,
 344 * "refs/heads/") or "" for the top-level directory.
 345 */
 346static struct ref_entry *create_dir_entry(struct ref_cache *ref_cache,
 347                                          const char *dirname, size_t len,
 348                                          int incomplete)
 349{
 350        struct ref_entry *direntry;
 351        direntry = xcalloc(1, sizeof(struct ref_entry) + len + 1);
 352        memcpy(direntry->name, dirname, len);
 353        direntry->name[len] = '\0';
 354        direntry->u.subdir.ref_cache = ref_cache;
 355        direntry->flag = REF_DIR | (incomplete ? REF_INCOMPLETE : 0);
 356        return direntry;
 357}
 358
 359static int ref_entry_cmp(const void *a, const void *b)
 360{
 361        struct ref_entry *one = *(struct ref_entry **)a;
 362        struct ref_entry *two = *(struct ref_entry **)b;
 363        return strcmp(one->name, two->name);
 364}
 365
 366static void sort_ref_dir(struct ref_dir *dir);
 367
 368struct string_slice {
 369        size_t len;
 370        const char *str;
 371};
 372
 373static int ref_entry_cmp_sslice(const void *key_, const void *ent_)
 374{
 375        const struct string_slice *key = key_;
 376        const struct ref_entry *ent = *(const struct ref_entry * const *)ent_;
 377        int cmp = strncmp(key->str, ent->name, key->len);
 378        if (cmp)
 379                return cmp;
 380        return '\0' - (unsigned char)ent->name[key->len];
 381}
 382
 383/*
 384 * Return the index of the entry with the given refname from the
 385 * ref_dir (non-recursively), sorting dir if necessary.  Return -1 if
 386 * no such entry is found.  dir must already be complete.
 387 */
 388static int search_ref_dir(struct ref_dir *dir, const char *refname, size_t len)
 389{
 390        struct ref_entry **r;
 391        struct string_slice key;
 392
 393        if (refname == NULL || !dir->nr)
 394                return -1;
 395
 396        sort_ref_dir(dir);
 397        key.len = len;
 398        key.str = refname;
 399        r = bsearch(&key, dir->entries, dir->nr, sizeof(*dir->entries),
 400                    ref_entry_cmp_sslice);
 401
 402        if (r == NULL)
 403                return -1;
 404
 405        return r - dir->entries;
 406}
 407
 408/*
 409 * Search for a directory entry directly within dir (without
 410 * recursing).  Sort dir if necessary.  subdirname must be a directory
 411 * name (i.e., end in '/').  If mkdir is set, then create the
 412 * directory if it is missing; otherwise, return NULL if the desired
 413 * directory cannot be found.  dir must already be complete.
 414 */
 415static struct ref_dir *search_for_subdir(struct ref_dir *dir,
 416                                         const char *subdirname, size_t len,
 417                                         int mkdir)
 418{
 419        int entry_index = search_ref_dir(dir, subdirname, len);
 420        struct ref_entry *entry;
 421        if (entry_index == -1) {
 422                if (!mkdir)
 423                        return NULL;
 424                /*
 425                 * Since dir is complete, the absence of a subdir
 426                 * means that the subdir really doesn't exist;
 427                 * therefore, create an empty record for it but mark
 428                 * the record complete.
 429                 */
 430                entry = create_dir_entry(dir->ref_cache, subdirname, len, 0);
 431                add_entry_to_dir(dir, entry);
 432        } else {
 433                entry = dir->entries[entry_index];
 434        }
 435        return get_ref_dir(entry);
 436}
 437
 438/*
 439 * If refname is a reference name, find the ref_dir within the dir
 440 * tree that should hold refname.  If refname is a directory name
 441 * (i.e., ends in '/'), then return that ref_dir itself.  dir must
 442 * represent the top-level directory and must already be complete.
 443 * Sort ref_dirs and recurse into subdirectories as necessary.  If
 444 * mkdir is set, then create any missing directories; otherwise,
 445 * return NULL if the desired directory cannot be found.
 446 */
 447static struct ref_dir *find_containing_dir(struct ref_dir *dir,
 448                                           const char *refname, int mkdir)
 449{
 450        const char *slash;
 451        for (slash = strchr(refname, '/'); slash; slash = strchr(slash + 1, '/')) {
 452                size_t dirnamelen = slash - refname + 1;
 453                struct ref_dir *subdir;
 454                subdir = search_for_subdir(dir, refname, dirnamelen, mkdir);
 455                if (!subdir) {
 456                        dir = NULL;
 457                        break;
 458                }
 459                dir = subdir;
 460        }
 461
 462        return dir;
 463}
 464
 465/*
 466 * Find the value entry with the given name in dir, sorting ref_dirs
 467 * and recursing into subdirectories as necessary.  If the name is not
 468 * found or it corresponds to a directory entry, return NULL.
 469 */
 470static struct ref_entry *find_ref(struct ref_dir *dir, const char *refname)
 471{
 472        int entry_index;
 473        struct ref_entry *entry;
 474        dir = find_containing_dir(dir, refname, 0);
 475        if (!dir)
 476                return NULL;
 477        entry_index = search_ref_dir(dir, refname, strlen(refname));
 478        if (entry_index == -1)
 479                return NULL;
 480        entry = dir->entries[entry_index];
 481        return (entry->flag & REF_DIR) ? NULL : entry;
 482}
 483
 484/*
 485 * Remove the entry with the given name from dir, recursing into
 486 * subdirectories as necessary.  If refname is the name of a directory
 487 * (i.e., ends with '/'), then remove the directory and its contents.
 488 * If the removal was successful, return the number of entries
 489 * remaining in the directory entry that contained the deleted entry.
 490 * If the name was not found, return -1.  Please note that this
 491 * function only deletes the entry from the cache; it does not delete
 492 * it from the filesystem or ensure that other cache entries (which
 493 * might be symbolic references to the removed entry) are updated.
 494 * Nor does it remove any containing dir entries that might be made
 495 * empty by the removal.  dir must represent the top-level directory
 496 * and must already be complete.
 497 */
 498static int remove_entry(struct ref_dir *dir, const char *refname)
 499{
 500        int refname_len = strlen(refname);
 501        int entry_index;
 502        struct ref_entry *entry;
 503        int is_dir = refname[refname_len - 1] == '/';
 504        if (is_dir) {
 505                /*
 506                 * refname represents a reference directory.  Remove
 507                 * the trailing slash; otherwise we will get the
 508                 * directory *representing* refname rather than the
 509                 * one *containing* it.
 510                 */
 511                char *dirname = xmemdupz(refname, refname_len - 1);
 512                dir = find_containing_dir(dir, dirname, 0);
 513                free(dirname);
 514        } else {
 515                dir = find_containing_dir(dir, refname, 0);
 516        }
 517        if (!dir)
 518                return -1;
 519        entry_index = search_ref_dir(dir, refname, refname_len);
 520        if (entry_index == -1)
 521                return -1;
 522        entry = dir->entries[entry_index];
 523
 524        memmove(&dir->entries[entry_index],
 525                &dir->entries[entry_index + 1],
 526                (dir->nr - entry_index - 1) * sizeof(*dir->entries)
 527                );
 528        dir->nr--;
 529        if (dir->sorted > entry_index)
 530                dir->sorted--;
 531        free_ref_entry(entry);
 532        return dir->nr;
 533}
 534
 535/*
 536 * Add a ref_entry to the ref_dir (unsorted), recursing into
 537 * subdirectories as necessary.  dir must represent the top-level
 538 * directory.  Return 0 on success.
 539 */
 540static int add_ref(struct ref_dir *dir, struct ref_entry *ref)
 541{
 542        dir = find_containing_dir(dir, ref->name, 1);
 543        if (!dir)
 544                return -1;
 545        add_entry_to_dir(dir, ref);
 546        return 0;
 547}
 548
 549/*
 550 * Emit a warning and return true iff ref1 and ref2 have the same name
 551 * and the same sha1.  Die if they have the same name but different
 552 * sha1s.
 553 */
 554static int is_dup_ref(const struct ref_entry *ref1, const struct ref_entry *ref2)
 555{
 556        if (strcmp(ref1->name, ref2->name))
 557                return 0;
 558
 559        /* Duplicate name; make sure that they don't conflict: */
 560
 561        if ((ref1->flag & REF_DIR) || (ref2->flag & REF_DIR))
 562                /* This is impossible by construction */
 563                die("Reference directory conflict: %s", ref1->name);
 564
 565        if (hashcmp(ref1->u.value.sha1, ref2->u.value.sha1))
 566                die("Duplicated ref, and SHA1s don't match: %s", ref1->name);
 567
 568        warning("Duplicated ref: %s", ref1->name);
 569        return 1;
 570}
 571
 572/*
 573 * Sort the entries in dir non-recursively (if they are not already
 574 * sorted) and remove any duplicate entries.
 575 */
 576static void sort_ref_dir(struct ref_dir *dir)
 577{
 578        int i, j;
 579        struct ref_entry *last = NULL;
 580
 581        /*
 582         * This check also prevents passing a zero-length array to qsort(),
 583         * which is a problem on some platforms.
 584         */
 585        if (dir->sorted == dir->nr)
 586                return;
 587
 588        qsort(dir->entries, dir->nr, sizeof(*dir->entries), ref_entry_cmp);
 589
 590        /* Remove any duplicates: */
 591        for (i = 0, j = 0; j < dir->nr; j++) {
 592                struct ref_entry *entry = dir->entries[j];
 593                if (last && is_dup_ref(last, entry))
 594                        free_ref_entry(entry);
 595                else
 596                        last = dir->entries[i++] = entry;
 597        }
 598        dir->sorted = dir->nr = i;
 599}
 600
 601/* Include broken references in a do_for_each_ref*() iteration: */
 602#define DO_FOR_EACH_INCLUDE_BROKEN 0x01
 603
 604/*
 605 * Return true iff the reference described by entry can be resolved to
 606 * an object in the database.  Emit a warning if the referred-to
 607 * object does not exist.
 608 */
 609static int ref_resolves_to_object(struct ref_entry *entry)
 610{
 611        if (entry->flag & REF_ISBROKEN)
 612                return 0;
 613        if (!has_sha1_file(entry->u.value.sha1)) {
 614                error("%s does not point to a valid object!", entry->name);
 615                return 0;
 616        }
 617        return 1;
 618}
 619
 620/*
 621 * current_ref is a performance hack: when iterating over references
 622 * using the for_each_ref*() functions, current_ref is set to the
 623 * current reference's entry before calling the callback function.  If
 624 * the callback function calls peel_ref(), then peel_ref() first
 625 * checks whether the reference to be peeled is the current reference
 626 * (it usually is) and if so, returns that reference's peeled version
 627 * if it is available.  This avoids a refname lookup in a common case.
 628 */
 629static struct ref_entry *current_ref;
 630
 631typedef int each_ref_entry_fn(struct ref_entry *entry, void *cb_data);
 632
 633struct ref_entry_cb {
 634        const char *base;
 635        int trim;
 636        int flags;
 637        each_ref_fn *fn;
 638        void *cb_data;
 639};
 640
 641/*
 642 * Handle one reference in a do_for_each_ref*()-style iteration,
 643 * calling an each_ref_fn for each entry.
 644 */
 645static int do_one_ref(struct ref_entry *entry, void *cb_data)
 646{
 647        struct ref_entry_cb *data = cb_data;
 648        struct ref_entry *old_current_ref;
 649        int retval;
 650
 651        if (!starts_with(entry->name, data->base))
 652                return 0;
 653
 654        if (!(data->flags & DO_FOR_EACH_INCLUDE_BROKEN) &&
 655              !ref_resolves_to_object(entry))
 656                return 0;
 657
 658        /* Store the old value, in case this is a recursive call: */
 659        old_current_ref = current_ref;
 660        current_ref = entry;
 661        retval = data->fn(entry->name + data->trim, entry->u.value.sha1,
 662                          entry->flag, data->cb_data);
 663        current_ref = old_current_ref;
 664        return retval;
 665}
 666
 667/*
 668 * Call fn for each reference in dir that has index in the range
 669 * offset <= index < dir->nr.  Recurse into subdirectories that are in
 670 * that index range, sorting them before iterating.  This function
 671 * does not sort dir itself; it should be sorted beforehand.  fn is
 672 * called for all references, including broken ones.
 673 */
 674static int do_for_each_entry_in_dir(struct ref_dir *dir, int offset,
 675                                    each_ref_entry_fn fn, void *cb_data)
 676{
 677        int i;
 678        assert(dir->sorted == dir->nr);
 679        for (i = offset; i < dir->nr; i++) {
 680                struct ref_entry *entry = dir->entries[i];
 681                int retval;
 682                if (entry->flag & REF_DIR) {
 683                        struct ref_dir *subdir = get_ref_dir(entry);
 684                        sort_ref_dir(subdir);
 685                        retval = do_for_each_entry_in_dir(subdir, 0, fn, cb_data);
 686                } else {
 687                        retval = fn(entry, cb_data);
 688                }
 689                if (retval)
 690                        return retval;
 691        }
 692        return 0;
 693}
 694
 695/*
 696 * Call fn for each reference in the union of dir1 and dir2, in order
 697 * by refname.  Recurse into subdirectories.  If a value entry appears
 698 * in both dir1 and dir2, then only process the version that is in
 699 * dir2.  The input dirs must already be sorted, but subdirs will be
 700 * sorted as needed.  fn is called for all references, including
 701 * broken ones.
 702 */
 703static int do_for_each_entry_in_dirs(struct ref_dir *dir1,
 704                                     struct ref_dir *dir2,
 705                                     each_ref_entry_fn fn, void *cb_data)
 706{
 707        int retval;
 708        int i1 = 0, i2 = 0;
 709
 710        assert(dir1->sorted == dir1->nr);
 711        assert(dir2->sorted == dir2->nr);
 712        while (1) {
 713                struct ref_entry *e1, *e2;
 714                int cmp;
 715                if (i1 == dir1->nr) {
 716                        return do_for_each_entry_in_dir(dir2, i2, fn, cb_data);
 717                }
 718                if (i2 == dir2->nr) {
 719                        return do_for_each_entry_in_dir(dir1, i1, fn, cb_data);
 720                }
 721                e1 = dir1->entries[i1];
 722                e2 = dir2->entries[i2];
 723                cmp = strcmp(e1->name, e2->name);
 724                if (cmp == 0) {
 725                        if ((e1->flag & REF_DIR) && (e2->flag & REF_DIR)) {
 726                                /* Both are directories; descend them in parallel. */
 727                                struct ref_dir *subdir1 = get_ref_dir(e1);
 728                                struct ref_dir *subdir2 = get_ref_dir(e2);
 729                                sort_ref_dir(subdir1);
 730                                sort_ref_dir(subdir2);
 731                                retval = do_for_each_entry_in_dirs(
 732                                                subdir1, subdir2, fn, cb_data);
 733                                i1++;
 734                                i2++;
 735                        } else if (!(e1->flag & REF_DIR) && !(e2->flag & REF_DIR)) {
 736                                /* Both are references; ignore the one from dir1. */
 737                                retval = fn(e2, cb_data);
 738                                i1++;
 739                                i2++;
 740                        } else {
 741                                die("conflict between reference and directory: %s",
 742                                    e1->name);
 743                        }
 744                } else {
 745                        struct ref_entry *e;
 746                        if (cmp < 0) {
 747                                e = e1;
 748                                i1++;
 749                        } else {
 750                                e = e2;
 751                                i2++;
 752                        }
 753                        if (e->flag & REF_DIR) {
 754                                struct ref_dir *subdir = get_ref_dir(e);
 755                                sort_ref_dir(subdir);
 756                                retval = do_for_each_entry_in_dir(
 757                                                subdir, 0, fn, cb_data);
 758                        } else {
 759                                retval = fn(e, cb_data);
 760                        }
 761                }
 762                if (retval)
 763                        return retval;
 764        }
 765}
 766
 767/*
 768 * Load all of the refs from the dir into our in-memory cache. The hard work
 769 * of loading loose refs is done by get_ref_dir(), so we just need to recurse
 770 * through all of the sub-directories. We do not even need to care about
 771 * sorting, as traversal order does not matter to us.
 772 */
 773static void prime_ref_dir(struct ref_dir *dir)
 774{
 775        int i;
 776        for (i = 0; i < dir->nr; i++) {
 777                struct ref_entry *entry = dir->entries[i];
 778                if (entry->flag & REF_DIR)
 779                        prime_ref_dir(get_ref_dir(entry));
 780        }
 781}
 782/*
 783 * Return true iff refname1 and refname2 conflict with each other.
 784 * Two reference names conflict if one of them exactly matches the
 785 * leading components of the other; e.g., "foo/bar" conflicts with
 786 * both "foo" and with "foo/bar/baz" but not with "foo/bar" or
 787 * "foo/barbados".
 788 */
 789static int names_conflict(const char *refname1, const char *refname2)
 790{
 791        for (; *refname1 && *refname1 == *refname2; refname1++, refname2++)
 792                ;
 793        return (*refname1 == '\0' && *refname2 == '/')
 794                || (*refname1 == '/' && *refname2 == '\0');
 795}
 796
 797struct name_conflict_cb {
 798        const char *refname;
 799        const char *oldrefname;
 800        const char *conflicting_refname;
 801};
 802
 803static int name_conflict_fn(struct ref_entry *entry, void *cb_data)
 804{
 805        struct name_conflict_cb *data = (struct name_conflict_cb *)cb_data;
 806        if (data->oldrefname && !strcmp(data->oldrefname, entry->name))
 807                return 0;
 808        if (names_conflict(data->refname, entry->name)) {
 809                data->conflicting_refname = entry->name;
 810                return 1;
 811        }
 812        return 0;
 813}
 814
 815/*
 816 * Return true iff a reference named refname could be created without
 817 * conflicting with the name of an existing reference in dir.  If
 818 * oldrefname is non-NULL, ignore potential conflicts with oldrefname
 819 * (e.g., because oldrefname is scheduled for deletion in the same
 820 * operation).
 821 */
 822static int is_refname_available(const char *refname, const char *oldrefname,
 823                                struct ref_dir *dir)
 824{
 825        struct name_conflict_cb data;
 826        data.refname = refname;
 827        data.oldrefname = oldrefname;
 828        data.conflicting_refname = NULL;
 829
 830        sort_ref_dir(dir);
 831        if (do_for_each_entry_in_dir(dir, 0, name_conflict_fn, &data)) {
 832                error("'%s' exists; cannot create '%s'",
 833                      data.conflicting_refname, refname);
 834                return 0;
 835        }
 836        return 1;
 837}
 838
 839struct packed_ref_cache {
 840        struct ref_entry *root;
 841
 842        /*
 843         * Count of references to the data structure in this instance,
 844         * including the pointer from ref_cache::packed if any.  The
 845         * data will not be freed as long as the reference count is
 846         * nonzero.
 847         */
 848        unsigned int referrers;
 849
 850        /*
 851         * Iff the packed-refs file associated with this instance is
 852         * currently locked for writing, this points at the associated
 853         * lock (which is owned by somebody else).  The referrer count
 854         * is also incremented when the file is locked and decremented
 855         * when it is unlocked.
 856         */
 857        struct lock_file *lock;
 858
 859        /* The metadata from when this packed-refs cache was read */
 860        struct stat_validity validity;
 861};
 862
 863/*
 864 * Future: need to be in "struct repository"
 865 * when doing a full libification.
 866 */
 867static struct ref_cache {
 868        struct ref_cache *next;
 869        struct ref_entry *loose;
 870        struct packed_ref_cache *packed;
 871        /*
 872         * The submodule name, or "" for the main repo.  We allocate
 873         * length 1 rather than FLEX_ARRAY so that the main ref_cache
 874         * is initialized correctly.
 875         */
 876        char name[1];
 877} ref_cache, *submodule_ref_caches;
 878
 879/* Lock used for the main packed-refs file: */
 880static struct lock_file packlock;
 881
 882/*
 883 * Increment the reference count of *packed_refs.
 884 */
 885static void acquire_packed_ref_cache(struct packed_ref_cache *packed_refs)
 886{
 887        packed_refs->referrers++;
 888}
 889
 890/*
 891 * Decrease the reference count of *packed_refs.  If it goes to zero,
 892 * free *packed_refs and return true; otherwise return false.
 893 */
 894static int release_packed_ref_cache(struct packed_ref_cache *packed_refs)
 895{
 896        if (!--packed_refs->referrers) {
 897                free_ref_entry(packed_refs->root);
 898                stat_validity_clear(&packed_refs->validity);
 899                free(packed_refs);
 900                return 1;
 901        } else {
 902                return 0;
 903        }
 904}
 905
 906static void clear_packed_ref_cache(struct ref_cache *refs)
 907{
 908        if (refs->packed) {
 909                struct packed_ref_cache *packed_refs = refs->packed;
 910
 911                if (packed_refs->lock)
 912                        die("internal error: packed-ref cache cleared while locked");
 913                refs->packed = NULL;
 914                release_packed_ref_cache(packed_refs);
 915        }
 916}
 917
 918static void clear_loose_ref_cache(struct ref_cache *refs)
 919{
 920        if (refs->loose) {
 921                free_ref_entry(refs->loose);
 922                refs->loose = NULL;
 923        }
 924}
 925
 926static struct ref_cache *create_ref_cache(const char *submodule)
 927{
 928        int len;
 929        struct ref_cache *refs;
 930        if (!submodule)
 931                submodule = "";
 932        len = strlen(submodule) + 1;
 933        refs = xcalloc(1, sizeof(struct ref_cache) + len);
 934        memcpy(refs->name, submodule, len);
 935        return refs;
 936}
 937
 938/*
 939 * Return a pointer to a ref_cache for the specified submodule. For
 940 * the main repository, use submodule==NULL. The returned structure
 941 * will be allocated and initialized but not necessarily populated; it
 942 * should not be freed.
 943 */
 944static struct ref_cache *get_ref_cache(const char *submodule)
 945{
 946        struct ref_cache *refs;
 947
 948        if (!submodule || !*submodule)
 949                return &ref_cache;
 950
 951        for (refs = submodule_ref_caches; refs; refs = refs->next)
 952                if (!strcmp(submodule, refs->name))
 953                        return refs;
 954
 955        refs = create_ref_cache(submodule);
 956        refs->next = submodule_ref_caches;
 957        submodule_ref_caches = refs;
 958        return refs;
 959}
 960
 961/* The length of a peeled reference line in packed-refs, including EOL: */
 962#define PEELED_LINE_LENGTH 42
 963
 964/*
 965 * The packed-refs header line that we write out.  Perhaps other
 966 * traits will be added later.  The trailing space is required.
 967 */
 968static const char PACKED_REFS_HEADER[] =
 969        "# pack-refs with: peeled fully-peeled \n";
 970
 971/*
 972 * Parse one line from a packed-refs file.  Write the SHA1 to sha1.
 973 * Return a pointer to the refname within the line (null-terminated),
 974 * or NULL if there was a problem.
 975 */
 976static const char *parse_ref_line(char *line, unsigned char *sha1)
 977{
 978        /*
 979         * 42: the answer to everything.
 980         *
 981         * In this case, it happens to be the answer to
 982         *  40 (length of sha1 hex representation)
 983         *  +1 (space in between hex and name)
 984         *  +1 (newline at the end of the line)
 985         */
 986        int len = strlen(line) - 42;
 987
 988        if (len <= 0)
 989                return NULL;
 990        if (get_sha1_hex(line, sha1) < 0)
 991                return NULL;
 992        if (!isspace(line[40]))
 993                return NULL;
 994        line += 41;
 995        if (isspace(*line))
 996                return NULL;
 997        if (line[len] != '\n')
 998                return NULL;
 999        line[len] = 0;
1000
1001        return line;
1002}
1003
1004/*
1005 * Read f, which is a packed-refs file, into dir.
1006 *
1007 * A comment line of the form "# pack-refs with: " may contain zero or
1008 * more traits. We interpret the traits as follows:
1009 *
1010 *   No traits:
1011 *
1012 *      Probably no references are peeled. But if the file contains a
1013 *      peeled value for a reference, we will use it.
1014 *
1015 *   peeled:
1016 *
1017 *      References under "refs/tags/", if they *can* be peeled, *are*
1018 *      peeled in this file. References outside of "refs/tags/" are
1019 *      probably not peeled even if they could have been, but if we find
1020 *      a peeled value for such a reference we will use it.
1021 *
1022 *   fully-peeled:
1023 *
1024 *      All references in the file that can be peeled are peeled.
1025 *      Inversely (and this is more important), any references in the
1026 *      file for which no peeled value is recorded is not peelable. This
1027 *      trait should typically be written alongside "peeled" for
1028 *      compatibility with older clients, but we do not require it
1029 *      (i.e., "peeled" is a no-op if "fully-peeled" is set).
1030 */
1031static void read_packed_refs(FILE *f, struct ref_dir *dir)
1032{
1033        struct ref_entry *last = NULL;
1034        char refline[PATH_MAX];
1035        enum { PEELED_NONE, PEELED_TAGS, PEELED_FULLY } peeled = PEELED_NONE;
1036
1037        while (fgets(refline, sizeof(refline), f)) {
1038                unsigned char sha1[20];
1039                const char *refname;
1040                static const char header[] = "# pack-refs with:";
1041
1042                if (!strncmp(refline, header, sizeof(header)-1)) {
1043                        const char *traits = refline + sizeof(header) - 1;
1044                        if (strstr(traits, " fully-peeled "))
1045                                peeled = PEELED_FULLY;
1046                        else if (strstr(traits, " peeled "))
1047                                peeled = PEELED_TAGS;
1048                        /* perhaps other traits later as well */
1049                        continue;
1050                }
1051
1052                refname = parse_ref_line(refline, sha1);
1053                if (refname) {
1054                        last = create_ref_entry(refname, sha1, REF_ISPACKED, 1);
1055                        if (peeled == PEELED_FULLY ||
1056                            (peeled == PEELED_TAGS && starts_with(refname, "refs/tags/")))
1057                                last->flag |= REF_KNOWS_PEELED;
1058                        add_ref(dir, last);
1059                        continue;
1060                }
1061                if (last &&
1062                    refline[0] == '^' &&
1063                    strlen(refline) == PEELED_LINE_LENGTH &&
1064                    refline[PEELED_LINE_LENGTH - 1] == '\n' &&
1065                    !get_sha1_hex(refline + 1, sha1)) {
1066                        hashcpy(last->u.value.peeled, sha1);
1067                        /*
1068                         * Regardless of what the file header said,
1069                         * we definitely know the value of *this*
1070                         * reference:
1071                         */
1072                        last->flag |= REF_KNOWS_PEELED;
1073                }
1074        }
1075}
1076
1077/*
1078 * Get the packed_ref_cache for the specified ref_cache, creating it
1079 * if necessary.
1080 */
1081static struct packed_ref_cache *get_packed_ref_cache(struct ref_cache *refs)
1082{
1083        const char *packed_refs_file;
1084
1085        if (*refs->name)
1086                packed_refs_file = git_path_submodule(refs->name, "packed-refs");
1087        else
1088                packed_refs_file = git_path("packed-refs");
1089
1090        if (refs->packed &&
1091            !stat_validity_check(&refs->packed->validity, packed_refs_file))
1092                clear_packed_ref_cache(refs);
1093
1094        if (!refs->packed) {
1095                FILE *f;
1096
1097                refs->packed = xcalloc(1, sizeof(*refs->packed));
1098                acquire_packed_ref_cache(refs->packed);
1099                refs->packed->root = create_dir_entry(refs, "", 0, 0);
1100                f = fopen(packed_refs_file, "r");
1101                if (f) {
1102                        stat_validity_update(&refs->packed->validity, fileno(f));
1103                        read_packed_refs(f, get_ref_dir(refs->packed->root));
1104                        fclose(f);
1105                }
1106        }
1107        return refs->packed;
1108}
1109
1110static struct ref_dir *get_packed_ref_dir(struct packed_ref_cache *packed_ref_cache)
1111{
1112        return get_ref_dir(packed_ref_cache->root);
1113}
1114
1115static struct ref_dir *get_packed_refs(struct ref_cache *refs)
1116{
1117        return get_packed_ref_dir(get_packed_ref_cache(refs));
1118}
1119
1120void add_packed_ref(const char *refname, const unsigned char *sha1)
1121{
1122        struct packed_ref_cache *packed_ref_cache =
1123                get_packed_ref_cache(&ref_cache);
1124
1125        if (!packed_ref_cache->lock)
1126                die("internal error: packed refs not locked");
1127        add_ref(get_packed_ref_dir(packed_ref_cache),
1128                create_ref_entry(refname, sha1, REF_ISPACKED, 1));
1129}
1130
1131/*
1132 * Read the loose references from the namespace dirname into dir
1133 * (without recursing).  dirname must end with '/'.  dir must be the
1134 * directory entry corresponding to dirname.
1135 */
1136static void read_loose_refs(const char *dirname, struct ref_dir *dir)
1137{
1138        struct ref_cache *refs = dir->ref_cache;
1139        DIR *d;
1140        const char *path;
1141        struct dirent *de;
1142        int dirnamelen = strlen(dirname);
1143        struct strbuf refname;
1144
1145        if (*refs->name)
1146                path = git_path_submodule(refs->name, "%s", dirname);
1147        else
1148                path = git_path("%s", dirname);
1149
1150        d = opendir(path);
1151        if (!d)
1152                return;
1153
1154        strbuf_init(&refname, dirnamelen + 257);
1155        strbuf_add(&refname, dirname, dirnamelen);
1156
1157        while ((de = readdir(d)) != NULL) {
1158                unsigned char sha1[20];
1159                struct stat st;
1160                int flag;
1161                const char *refdir;
1162
1163                if (de->d_name[0] == '.')
1164                        continue;
1165                if (has_extension(de->d_name, ".lock"))
1166                        continue;
1167                strbuf_addstr(&refname, de->d_name);
1168                refdir = *refs->name
1169                        ? git_path_submodule(refs->name, "%s", refname.buf)
1170                        : git_path("%s", refname.buf);
1171                if (stat(refdir, &st) < 0) {
1172                        ; /* silently ignore */
1173                } else if (S_ISDIR(st.st_mode)) {
1174                        strbuf_addch(&refname, '/');
1175                        add_entry_to_dir(dir,
1176                                         create_dir_entry(refs, refname.buf,
1177                                                          refname.len, 1));
1178                } else {
1179                        if (*refs->name) {
1180                                hashclr(sha1);
1181                                flag = 0;
1182                                if (resolve_gitlink_ref(refs->name, refname.buf, sha1) < 0) {
1183                                        hashclr(sha1);
1184                                        flag |= REF_ISBROKEN;
1185                                }
1186                        } else if (read_ref_full(refname.buf, sha1, 1, &flag)) {
1187                                hashclr(sha1);
1188                                flag |= REF_ISBROKEN;
1189                        }
1190                        add_entry_to_dir(dir,
1191                                         create_ref_entry(refname.buf, sha1, flag, 1));
1192                }
1193                strbuf_setlen(&refname, dirnamelen);
1194        }
1195        strbuf_release(&refname);
1196        closedir(d);
1197}
1198
1199static struct ref_dir *get_loose_refs(struct ref_cache *refs)
1200{
1201        if (!refs->loose) {
1202                /*
1203                 * Mark the top-level directory complete because we
1204                 * are about to read the only subdirectory that can
1205                 * hold references:
1206                 */
1207                refs->loose = create_dir_entry(refs, "", 0, 0);
1208                /*
1209                 * Create an incomplete entry for "refs/":
1210                 */
1211                add_entry_to_dir(get_ref_dir(refs->loose),
1212                                 create_dir_entry(refs, "refs/", 5, 1));
1213        }
1214        return get_ref_dir(refs->loose);
1215}
1216
1217/* We allow "recursive" symbolic refs. Only within reason, though */
1218#define MAXDEPTH 5
1219#define MAXREFLEN (1024)
1220
1221/*
1222 * Called by resolve_gitlink_ref_recursive() after it failed to read
1223 * from the loose refs in ref_cache refs. Find <refname> in the
1224 * packed-refs file for the submodule.
1225 */
1226static int resolve_gitlink_packed_ref(struct ref_cache *refs,
1227                                      const char *refname, unsigned char *sha1)
1228{
1229        struct ref_entry *ref;
1230        struct ref_dir *dir = get_packed_refs(refs);
1231
1232        ref = find_ref(dir, refname);
1233        if (ref == NULL)
1234                return -1;
1235
1236        hashcpy(sha1, ref->u.value.sha1);
1237        return 0;
1238}
1239
1240static int resolve_gitlink_ref_recursive(struct ref_cache *refs,
1241                                         const char *refname, unsigned char *sha1,
1242                                         int recursion)
1243{
1244        int fd, len;
1245        char buffer[128], *p;
1246        char *path;
1247
1248        if (recursion > MAXDEPTH || strlen(refname) > MAXREFLEN)
1249                return -1;
1250        path = *refs->name
1251                ? git_path_submodule(refs->name, "%s", refname)
1252                : git_path("%s", refname);
1253        fd = open(path, O_RDONLY);
1254        if (fd < 0)
1255                return resolve_gitlink_packed_ref(refs, refname, sha1);
1256
1257        len = read(fd, buffer, sizeof(buffer)-1);
1258        close(fd);
1259        if (len < 0)
1260                return -1;
1261        while (len && isspace(buffer[len-1]))
1262                len--;
1263        buffer[len] = 0;
1264
1265        /* Was it a detached head or an old-fashioned symlink? */
1266        if (!get_sha1_hex(buffer, sha1))
1267                return 0;
1268
1269        /* Symref? */
1270        if (strncmp(buffer, "ref:", 4))
1271                return -1;
1272        p = buffer + 4;
1273        while (isspace(*p))
1274                p++;
1275
1276        return resolve_gitlink_ref_recursive(refs, p, sha1, recursion+1);
1277}
1278
1279int resolve_gitlink_ref(const char *path, const char *refname, unsigned char *sha1)
1280{
1281        int len = strlen(path), retval;
1282        char *submodule;
1283        struct ref_cache *refs;
1284
1285        while (len && path[len-1] == '/')
1286                len--;
1287        if (!len)
1288                return -1;
1289        submodule = xstrndup(path, len);
1290        refs = get_ref_cache(submodule);
1291        free(submodule);
1292
1293        retval = resolve_gitlink_ref_recursive(refs, refname, sha1, 0);
1294        return retval;
1295}
1296
1297/*
1298 * Return the ref_entry for the given refname from the packed
1299 * references.  If it does not exist, return NULL.
1300 */
1301static struct ref_entry *get_packed_ref(const char *refname)
1302{
1303        return find_ref(get_packed_refs(&ref_cache), refname);
1304}
1305
1306/*
1307 * A loose ref file doesn't exist; check for a packed ref.  The
1308 * options are forwarded from resolve_safe_unsafe().
1309 */
1310static const char *handle_missing_loose_ref(const char *refname,
1311                                            unsigned char *sha1,
1312                                            int reading,
1313                                            int *flag)
1314{
1315        struct ref_entry *entry;
1316
1317        /*
1318         * The loose reference file does not exist; check for a packed
1319         * reference.
1320         */
1321        entry = get_packed_ref(refname);
1322        if (entry) {
1323                hashcpy(sha1, entry->u.value.sha1);
1324                if (flag)
1325                        *flag |= REF_ISPACKED;
1326                return refname;
1327        }
1328        /* The reference is not a packed reference, either. */
1329        if (reading) {
1330                return NULL;
1331        } else {
1332                hashclr(sha1);
1333                return refname;
1334        }
1335}
1336
1337/* This function needs to return a meaningful errno on failure */
1338const char *resolve_ref_unsafe(const char *refname, unsigned char *sha1, int reading, int *flag)
1339{
1340        int depth = MAXDEPTH;
1341        ssize_t len;
1342        char buffer[256];
1343        static char refname_buffer[256];
1344
1345        if (flag)
1346                *flag = 0;
1347
1348        if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL)) {
1349                errno = EINVAL;
1350                return NULL;
1351        }
1352
1353        for (;;) {
1354                char path[PATH_MAX];
1355                struct stat st;
1356                char *buf;
1357                int fd;
1358
1359                if (--depth < 0) {
1360                        errno = ELOOP;
1361                        return NULL;
1362                }
1363
1364                git_snpath(path, sizeof(path), "%s", refname);
1365
1366                /*
1367                 * We might have to loop back here to avoid a race
1368                 * condition: first we lstat() the file, then we try
1369                 * to read it as a link or as a file.  But if somebody
1370                 * changes the type of the file (file <-> directory
1371                 * <-> symlink) between the lstat() and reading, then
1372                 * we don't want to report that as an error but rather
1373                 * try again starting with the lstat().
1374                 */
1375        stat_ref:
1376                if (lstat(path, &st) < 0) {
1377                        if (errno == ENOENT)
1378                                return handle_missing_loose_ref(refname, sha1,
1379                                                                reading, flag);
1380                        else
1381                                return NULL;
1382                }
1383
1384                /* Follow "normalized" - ie "refs/.." symlinks by hand */
1385                if (S_ISLNK(st.st_mode)) {
1386                        len = readlink(path, buffer, sizeof(buffer)-1);
1387                        if (len < 0) {
1388                                if (errno == ENOENT || errno == EINVAL)
1389                                        /* inconsistent with lstat; retry */
1390                                        goto stat_ref;
1391                                else
1392                                        return NULL;
1393                        }
1394                        buffer[len] = 0;
1395                        if (starts_with(buffer, "refs/") &&
1396                                        !check_refname_format(buffer, 0)) {
1397                                strcpy(refname_buffer, buffer);
1398                                refname = refname_buffer;
1399                                if (flag)
1400                                        *flag |= REF_ISSYMREF;
1401                                continue;
1402                        }
1403                }
1404
1405                /* Is it a directory? */
1406                if (S_ISDIR(st.st_mode)) {
1407                        errno = EISDIR;
1408                        return NULL;
1409                }
1410
1411                /*
1412                 * Anything else, just open it and try to use it as
1413                 * a ref
1414                 */
1415                fd = open(path, O_RDONLY);
1416                if (fd < 0) {
1417                        if (errno == ENOENT)
1418                                /* inconsistent with lstat; retry */
1419                                goto stat_ref;
1420                        else
1421                                return NULL;
1422                }
1423                len = read_in_full(fd, buffer, sizeof(buffer)-1);
1424                if (len < 0) {
1425                        int save_errno = errno;
1426                        close(fd);
1427                        errno = save_errno;
1428                        return NULL;
1429                }
1430                close(fd);
1431                while (len && isspace(buffer[len-1]))
1432                        len--;
1433                buffer[len] = '\0';
1434
1435                /*
1436                 * Is it a symbolic ref?
1437                 */
1438                if (!starts_with(buffer, "ref:")) {
1439                        /*
1440                         * Please note that FETCH_HEAD has a second
1441                         * line containing other data.
1442                         */
1443                        if (get_sha1_hex(buffer, sha1) ||
1444                            (buffer[40] != '\0' && !isspace(buffer[40]))) {
1445                                if (flag)
1446                                        *flag |= REF_ISBROKEN;
1447                                errno = EINVAL;
1448                                return NULL;
1449                        }
1450                        return refname;
1451                }
1452                if (flag)
1453                        *flag |= REF_ISSYMREF;
1454                buf = buffer + 4;
1455                while (isspace(*buf))
1456                        buf++;
1457                if (check_refname_format(buf, REFNAME_ALLOW_ONELEVEL)) {
1458                        if (flag)
1459                                *flag |= REF_ISBROKEN;
1460                        errno = EINVAL;
1461                        return NULL;
1462                }
1463                refname = strcpy(refname_buffer, buf);
1464        }
1465}
1466
1467char *resolve_refdup(const char *ref, unsigned char *sha1, int reading, int *flag)
1468{
1469        const char *ret = resolve_ref_unsafe(ref, sha1, reading, flag);
1470        return ret ? xstrdup(ret) : NULL;
1471}
1472
1473/* The argument to filter_refs */
1474struct ref_filter {
1475        const char *pattern;
1476        each_ref_fn *fn;
1477        void *cb_data;
1478};
1479
1480int read_ref_full(const char *refname, unsigned char *sha1, int reading, int *flags)
1481{
1482        if (resolve_ref_unsafe(refname, sha1, reading, flags))
1483                return 0;
1484        return -1;
1485}
1486
1487int read_ref(const char *refname, unsigned char *sha1)
1488{
1489        return read_ref_full(refname, sha1, 1, NULL);
1490}
1491
1492int ref_exists(const char *refname)
1493{
1494        unsigned char sha1[20];
1495        return !!resolve_ref_unsafe(refname, sha1, 1, NULL);
1496}
1497
1498static int filter_refs(const char *refname, const unsigned char *sha1, int flags,
1499                       void *data)
1500{
1501        struct ref_filter *filter = (struct ref_filter *)data;
1502        if (wildmatch(filter->pattern, refname, 0, NULL))
1503                return 0;
1504        return filter->fn(refname, sha1, flags, filter->cb_data);
1505}
1506
1507enum peel_status {
1508        /* object was peeled successfully: */
1509        PEEL_PEELED = 0,
1510
1511        /*
1512         * object cannot be peeled because the named object (or an
1513         * object referred to by a tag in the peel chain), does not
1514         * exist.
1515         */
1516        PEEL_INVALID = -1,
1517
1518        /* object cannot be peeled because it is not a tag: */
1519        PEEL_NON_TAG = -2,
1520
1521        /* ref_entry contains no peeled value because it is a symref: */
1522        PEEL_IS_SYMREF = -3,
1523
1524        /*
1525         * ref_entry cannot be peeled because it is broken (i.e., the
1526         * symbolic reference cannot even be resolved to an object
1527         * name):
1528         */
1529        PEEL_BROKEN = -4
1530};
1531
1532/*
1533 * Peel the named object; i.e., if the object is a tag, resolve the
1534 * tag recursively until a non-tag is found.  If successful, store the
1535 * result to sha1 and return PEEL_PEELED.  If the object is not a tag
1536 * or is not valid, return PEEL_NON_TAG or PEEL_INVALID, respectively,
1537 * and leave sha1 unchanged.
1538 */
1539static enum peel_status peel_object(const unsigned char *name, unsigned char *sha1)
1540{
1541        struct object *o = lookup_unknown_object(name);
1542
1543        if (o->type == OBJ_NONE) {
1544                int type = sha1_object_info(name, NULL);
1545                if (type < 0)
1546                        return PEEL_INVALID;
1547                o->type = type;
1548        }
1549
1550        if (o->type != OBJ_TAG)
1551                return PEEL_NON_TAG;
1552
1553        o = deref_tag_noverify(o);
1554        if (!o)
1555                return PEEL_INVALID;
1556
1557        hashcpy(sha1, o->sha1);
1558        return PEEL_PEELED;
1559}
1560
1561/*
1562 * Peel the entry (if possible) and return its new peel_status.  If
1563 * repeel is true, re-peel the entry even if there is an old peeled
1564 * value that is already stored in it.
1565 *
1566 * It is OK to call this function with a packed reference entry that
1567 * might be stale and might even refer to an object that has since
1568 * been garbage-collected.  In such a case, if the entry has
1569 * REF_KNOWS_PEELED then leave the status unchanged and return
1570 * PEEL_PEELED or PEEL_NON_TAG; otherwise, return PEEL_INVALID.
1571 */
1572static enum peel_status peel_entry(struct ref_entry *entry, int repeel)
1573{
1574        enum peel_status status;
1575
1576        if (entry->flag & REF_KNOWS_PEELED) {
1577                if (repeel) {
1578                        entry->flag &= ~REF_KNOWS_PEELED;
1579                        hashclr(entry->u.value.peeled);
1580                } else {
1581                        return is_null_sha1(entry->u.value.peeled) ?
1582                                PEEL_NON_TAG : PEEL_PEELED;
1583                }
1584        }
1585        if (entry->flag & REF_ISBROKEN)
1586                return PEEL_BROKEN;
1587        if (entry->flag & REF_ISSYMREF)
1588                return PEEL_IS_SYMREF;
1589
1590        status = peel_object(entry->u.value.sha1, entry->u.value.peeled);
1591        if (status == PEEL_PEELED || status == PEEL_NON_TAG)
1592                entry->flag |= REF_KNOWS_PEELED;
1593        return status;
1594}
1595
1596int peel_ref(const char *refname, unsigned char *sha1)
1597{
1598        int flag;
1599        unsigned char base[20];
1600
1601        if (current_ref && (current_ref->name == refname
1602                            || !strcmp(current_ref->name, refname))) {
1603                if (peel_entry(current_ref, 0))
1604                        return -1;
1605                hashcpy(sha1, current_ref->u.value.peeled);
1606                return 0;
1607        }
1608
1609        if (read_ref_full(refname, base, 1, &flag))
1610                return -1;
1611
1612        /*
1613         * If the reference is packed, read its ref_entry from the
1614         * cache in the hope that we already know its peeled value.
1615         * We only try this optimization on packed references because
1616         * (a) forcing the filling of the loose reference cache could
1617         * be expensive and (b) loose references anyway usually do not
1618         * have REF_KNOWS_PEELED.
1619         */
1620        if (flag & REF_ISPACKED) {
1621                struct ref_entry *r = get_packed_ref(refname);
1622                if (r) {
1623                        if (peel_entry(r, 0))
1624                                return -1;
1625                        hashcpy(sha1, r->u.value.peeled);
1626                        return 0;
1627                }
1628        }
1629
1630        return peel_object(base, sha1);
1631}
1632
1633struct warn_if_dangling_data {
1634        FILE *fp;
1635        const char *refname;
1636        const struct string_list *refnames;
1637        const char *msg_fmt;
1638};
1639
1640static int warn_if_dangling_symref(const char *refname, const unsigned char *sha1,
1641                                   int flags, void *cb_data)
1642{
1643        struct warn_if_dangling_data *d = cb_data;
1644        const char *resolves_to;
1645        unsigned char junk[20];
1646
1647        if (!(flags & REF_ISSYMREF))
1648                return 0;
1649
1650        resolves_to = resolve_ref_unsafe(refname, junk, 0, NULL);
1651        if (!resolves_to
1652            || (d->refname
1653                ? strcmp(resolves_to, d->refname)
1654                : !string_list_has_string(d->refnames, resolves_to))) {
1655                return 0;
1656        }
1657
1658        fprintf(d->fp, d->msg_fmt, refname);
1659        fputc('\n', d->fp);
1660        return 0;
1661}
1662
1663void warn_dangling_symref(FILE *fp, const char *msg_fmt, const char *refname)
1664{
1665        struct warn_if_dangling_data data;
1666
1667        data.fp = fp;
1668        data.refname = refname;
1669        data.refnames = NULL;
1670        data.msg_fmt = msg_fmt;
1671        for_each_rawref(warn_if_dangling_symref, &data);
1672}
1673
1674void warn_dangling_symrefs(FILE *fp, const char *msg_fmt, const struct string_list *refnames)
1675{
1676        struct warn_if_dangling_data data;
1677
1678        data.fp = fp;
1679        data.refname = NULL;
1680        data.refnames = refnames;
1681        data.msg_fmt = msg_fmt;
1682        for_each_rawref(warn_if_dangling_symref, &data);
1683}
1684
1685/*
1686 * Call fn for each reference in the specified ref_cache, omitting
1687 * references not in the containing_dir of base.  fn is called for all
1688 * references, including broken ones.  If fn ever returns a non-zero
1689 * value, stop the iteration and return that value; otherwise, return
1690 * 0.
1691 */
1692static int do_for_each_entry(struct ref_cache *refs, const char *base,
1693                             each_ref_entry_fn fn, void *cb_data)
1694{
1695        struct packed_ref_cache *packed_ref_cache;
1696        struct ref_dir *loose_dir;
1697        struct ref_dir *packed_dir;
1698        int retval = 0;
1699
1700        /*
1701         * We must make sure that all loose refs are read before accessing the
1702         * packed-refs file; this avoids a race condition in which loose refs
1703         * are migrated to the packed-refs file by a simultaneous process, but
1704         * our in-memory view is from before the migration. get_packed_ref_cache()
1705         * takes care of making sure our view is up to date with what is on
1706         * disk.
1707         */
1708        loose_dir = get_loose_refs(refs);
1709        if (base && *base) {
1710                loose_dir = find_containing_dir(loose_dir, base, 0);
1711        }
1712        if (loose_dir)
1713                prime_ref_dir(loose_dir);
1714
1715        packed_ref_cache = get_packed_ref_cache(refs);
1716        acquire_packed_ref_cache(packed_ref_cache);
1717        packed_dir = get_packed_ref_dir(packed_ref_cache);
1718        if (base && *base) {
1719                packed_dir = find_containing_dir(packed_dir, base, 0);
1720        }
1721
1722        if (packed_dir && loose_dir) {
1723                sort_ref_dir(packed_dir);
1724                sort_ref_dir(loose_dir);
1725                retval = do_for_each_entry_in_dirs(
1726                                packed_dir, loose_dir, fn, cb_data);
1727        } else if (packed_dir) {
1728                sort_ref_dir(packed_dir);
1729                retval = do_for_each_entry_in_dir(
1730                                packed_dir, 0, fn, cb_data);
1731        } else if (loose_dir) {
1732                sort_ref_dir(loose_dir);
1733                retval = do_for_each_entry_in_dir(
1734                                loose_dir, 0, fn, cb_data);
1735        }
1736
1737        release_packed_ref_cache(packed_ref_cache);
1738        return retval;
1739}
1740
1741/*
1742 * Call fn for each reference in the specified ref_cache for which the
1743 * refname begins with base.  If trim is non-zero, then trim that many
1744 * characters off the beginning of each refname before passing the
1745 * refname to fn.  flags can be DO_FOR_EACH_INCLUDE_BROKEN to include
1746 * broken references in the iteration.  If fn ever returns a non-zero
1747 * value, stop the iteration and return that value; otherwise, return
1748 * 0.
1749 */
1750static int do_for_each_ref(struct ref_cache *refs, const char *base,
1751                           each_ref_fn fn, int trim, int flags, void *cb_data)
1752{
1753        struct ref_entry_cb data;
1754        data.base = base;
1755        data.trim = trim;
1756        data.flags = flags;
1757        data.fn = fn;
1758        data.cb_data = cb_data;
1759
1760        return do_for_each_entry(refs, base, do_one_ref, &data);
1761}
1762
1763static int do_head_ref(const char *submodule, each_ref_fn fn, void *cb_data)
1764{
1765        unsigned char sha1[20];
1766        int flag;
1767
1768        if (submodule) {
1769                if (resolve_gitlink_ref(submodule, "HEAD", sha1) == 0)
1770                        return fn("HEAD", sha1, 0, cb_data);
1771
1772                return 0;
1773        }
1774
1775        if (!read_ref_full("HEAD", sha1, 1, &flag))
1776                return fn("HEAD", sha1, flag, cb_data);
1777
1778        return 0;
1779}
1780
1781int head_ref(each_ref_fn fn, void *cb_data)
1782{
1783        return do_head_ref(NULL, fn, cb_data);
1784}
1785
1786int head_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
1787{
1788        return do_head_ref(submodule, fn, cb_data);
1789}
1790
1791int for_each_ref(each_ref_fn fn, void *cb_data)
1792{
1793        return do_for_each_ref(&ref_cache, "", fn, 0, 0, cb_data);
1794}
1795
1796int for_each_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
1797{
1798        return do_for_each_ref(get_ref_cache(submodule), "", fn, 0, 0, cb_data);
1799}
1800
1801int for_each_ref_in(const char *prefix, each_ref_fn fn, void *cb_data)
1802{
1803        return do_for_each_ref(&ref_cache, prefix, fn, strlen(prefix), 0, cb_data);
1804}
1805
1806int for_each_ref_in_submodule(const char *submodule, const char *prefix,
1807                each_ref_fn fn, void *cb_data)
1808{
1809        return do_for_each_ref(get_ref_cache(submodule), prefix, fn, strlen(prefix), 0, cb_data);
1810}
1811
1812int for_each_tag_ref(each_ref_fn fn, void *cb_data)
1813{
1814        return for_each_ref_in("refs/tags/", fn, cb_data);
1815}
1816
1817int for_each_tag_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
1818{
1819        return for_each_ref_in_submodule(submodule, "refs/tags/", fn, cb_data);
1820}
1821
1822int for_each_branch_ref(each_ref_fn fn, void *cb_data)
1823{
1824        return for_each_ref_in("refs/heads/", fn, cb_data);
1825}
1826
1827int for_each_branch_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
1828{
1829        return for_each_ref_in_submodule(submodule, "refs/heads/", fn, cb_data);
1830}
1831
1832int for_each_remote_ref(each_ref_fn fn, void *cb_data)
1833{
1834        return for_each_ref_in("refs/remotes/", fn, cb_data);
1835}
1836
1837int for_each_remote_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
1838{
1839        return for_each_ref_in_submodule(submodule, "refs/remotes/", fn, cb_data);
1840}
1841
1842int for_each_replace_ref(each_ref_fn fn, void *cb_data)
1843{
1844        return do_for_each_ref(&ref_cache, "refs/replace/", fn, 13, 0, cb_data);
1845}
1846
1847int head_ref_namespaced(each_ref_fn fn, void *cb_data)
1848{
1849        struct strbuf buf = STRBUF_INIT;
1850        int ret = 0;
1851        unsigned char sha1[20];
1852        int flag;
1853
1854        strbuf_addf(&buf, "%sHEAD", get_git_namespace());
1855        if (!read_ref_full(buf.buf, sha1, 1, &flag))
1856                ret = fn(buf.buf, sha1, flag, cb_data);
1857        strbuf_release(&buf);
1858
1859        return ret;
1860}
1861
1862int for_each_namespaced_ref(each_ref_fn fn, void *cb_data)
1863{
1864        struct strbuf buf = STRBUF_INIT;
1865        int ret;
1866        strbuf_addf(&buf, "%srefs/", get_git_namespace());
1867        ret = do_for_each_ref(&ref_cache, buf.buf, fn, 0, 0, cb_data);
1868        strbuf_release(&buf);
1869        return ret;
1870}
1871
1872int for_each_glob_ref_in(each_ref_fn fn, const char *pattern,
1873        const char *prefix, void *cb_data)
1874{
1875        struct strbuf real_pattern = STRBUF_INIT;
1876        struct ref_filter filter;
1877        int ret;
1878
1879        if (!prefix && !starts_with(pattern, "refs/"))
1880                strbuf_addstr(&real_pattern, "refs/");
1881        else if (prefix)
1882                strbuf_addstr(&real_pattern, prefix);
1883        strbuf_addstr(&real_pattern, pattern);
1884
1885        if (!has_glob_specials(pattern)) {
1886                /* Append implied '/' '*' if not present. */
1887                if (real_pattern.buf[real_pattern.len - 1] != '/')
1888                        strbuf_addch(&real_pattern, '/');
1889                /* No need to check for '*', there is none. */
1890                strbuf_addch(&real_pattern, '*');
1891        }
1892
1893        filter.pattern = real_pattern.buf;
1894        filter.fn = fn;
1895        filter.cb_data = cb_data;
1896        ret = for_each_ref(filter_refs, &filter);
1897
1898        strbuf_release(&real_pattern);
1899        return ret;
1900}
1901
1902int for_each_glob_ref(each_ref_fn fn, const char *pattern, void *cb_data)
1903{
1904        return for_each_glob_ref_in(fn, pattern, NULL, cb_data);
1905}
1906
1907int for_each_rawref(each_ref_fn fn, void *cb_data)
1908{
1909        return do_for_each_ref(&ref_cache, "", fn, 0,
1910                               DO_FOR_EACH_INCLUDE_BROKEN, cb_data);
1911}
1912
1913const char *prettify_refname(const char *name)
1914{
1915        return name + (
1916                starts_with(name, "refs/heads/") ? 11 :
1917                starts_with(name, "refs/tags/") ? 10 :
1918                starts_with(name, "refs/remotes/") ? 13 :
1919                0);
1920}
1921
1922static const char *ref_rev_parse_rules[] = {
1923        "%.*s",
1924        "refs/%.*s",
1925        "refs/tags/%.*s",
1926        "refs/heads/%.*s",
1927        "refs/remotes/%.*s",
1928        "refs/remotes/%.*s/HEAD",
1929        NULL
1930};
1931
1932int refname_match(const char *abbrev_name, const char *full_name)
1933{
1934        const char **p;
1935        const int abbrev_name_len = strlen(abbrev_name);
1936
1937        for (p = ref_rev_parse_rules; *p; p++) {
1938                if (!strcmp(full_name, mkpath(*p, abbrev_name_len, abbrev_name))) {
1939                        return 1;
1940                }
1941        }
1942
1943        return 0;
1944}
1945
1946/* This function should make sure errno is meaningful on error */
1947static struct ref_lock *verify_lock(struct ref_lock *lock,
1948        const unsigned char *old_sha1, int mustexist)
1949{
1950        if (read_ref_full(lock->ref_name, lock->old_sha1, mustexist, NULL)) {
1951                int save_errno = errno;
1952                error("Can't verify ref %s", lock->ref_name);
1953                unlock_ref(lock);
1954                errno = save_errno;
1955                return NULL;
1956        }
1957        if (hashcmp(lock->old_sha1, old_sha1)) {
1958                error("Ref %s is at %s but expected %s", lock->ref_name,
1959                        sha1_to_hex(lock->old_sha1), sha1_to_hex(old_sha1));
1960                unlock_ref(lock);
1961                errno = EBUSY;
1962                return NULL;
1963        }
1964        return lock;
1965}
1966
1967static int remove_empty_directories(const char *file)
1968{
1969        /* we want to create a file but there is a directory there;
1970         * if that is an empty directory (or a directory that contains
1971         * only empty directories), remove them.
1972         */
1973        struct strbuf path;
1974        int result, save_errno;
1975
1976        strbuf_init(&path, 20);
1977        strbuf_addstr(&path, file);
1978
1979        result = remove_dir_recursively(&path, REMOVE_DIR_EMPTY_ONLY);
1980        save_errno = errno;
1981
1982        strbuf_release(&path);
1983        errno = save_errno;
1984
1985        return result;
1986}
1987
1988/*
1989 * *string and *len will only be substituted, and *string returned (for
1990 * later free()ing) if the string passed in is a magic short-hand form
1991 * to name a branch.
1992 */
1993static char *substitute_branch_name(const char **string, int *len)
1994{
1995        struct strbuf buf = STRBUF_INIT;
1996        int ret = interpret_branch_name(*string, *len, &buf);
1997
1998        if (ret == *len) {
1999                size_t size;
2000                *string = strbuf_detach(&buf, &size);
2001                *len = size;
2002                return (char *)*string;
2003        }
2004
2005        return NULL;
2006}
2007
2008int dwim_ref(const char *str, int len, unsigned char *sha1, char **ref)
2009{
2010        char *last_branch = substitute_branch_name(&str, &len);
2011        const char **p, *r;
2012        int refs_found = 0;
2013
2014        *ref = NULL;
2015        for (p = ref_rev_parse_rules; *p; p++) {
2016                char fullref[PATH_MAX];
2017                unsigned char sha1_from_ref[20];
2018                unsigned char *this_result;
2019                int flag;
2020
2021                this_result = refs_found ? sha1_from_ref : sha1;
2022                mksnpath(fullref, sizeof(fullref), *p, len, str);
2023                r = resolve_ref_unsafe(fullref, this_result, 1, &flag);
2024                if (r) {
2025                        if (!refs_found++)
2026                                *ref = xstrdup(r);
2027                        if (!warn_ambiguous_refs)
2028                                break;
2029                } else if ((flag & REF_ISSYMREF) && strcmp(fullref, "HEAD")) {
2030                        warning("ignoring dangling symref %s.", fullref);
2031                } else if ((flag & REF_ISBROKEN) && strchr(fullref, '/')) {
2032                        warning("ignoring broken ref %s.", fullref);
2033                }
2034        }
2035        free(last_branch);
2036        return refs_found;
2037}
2038
2039int dwim_log(const char *str, int len, unsigned char *sha1, char **log)
2040{
2041        char *last_branch = substitute_branch_name(&str, &len);
2042        const char **p;
2043        int logs_found = 0;
2044
2045        *log = NULL;
2046        for (p = ref_rev_parse_rules; *p; p++) {
2047                unsigned char hash[20];
2048                char path[PATH_MAX];
2049                const char *ref, *it;
2050
2051                mksnpath(path, sizeof(path), *p, len, str);
2052                ref = resolve_ref_unsafe(path, hash, 1, NULL);
2053                if (!ref)
2054                        continue;
2055                if (reflog_exists(path))
2056                        it = path;
2057                else if (strcmp(ref, path) && reflog_exists(ref))
2058                        it = ref;
2059                else
2060                        continue;
2061                if (!logs_found++) {
2062                        *log = xstrdup(it);
2063                        hashcpy(sha1, hash);
2064                }
2065                if (!warn_ambiguous_refs)
2066                        break;
2067        }
2068        free(last_branch);
2069        return logs_found;
2070}
2071
2072/*
2073 * Locks a "refs/" ref returning the lock on success and NULL on failure.
2074 * On failure errno is set to something meaningful.
2075 */
2076static struct ref_lock *lock_ref_sha1_basic(const char *refname,
2077                                            const unsigned char *old_sha1,
2078                                            int flags, int *type_p)
2079{
2080        char *ref_file;
2081        const char *orig_refname = refname;
2082        struct ref_lock *lock;
2083        int last_errno = 0;
2084        int type, lflags;
2085        int mustexist = (old_sha1 && !is_null_sha1(old_sha1));
2086        int missing = 0;
2087        int attempts_remaining = 3;
2088
2089        lock = xcalloc(1, sizeof(struct ref_lock));
2090        lock->lock_fd = -1;
2091
2092        refname = resolve_ref_unsafe(refname, lock->old_sha1, mustexist, &type);
2093        if (!refname && errno == EISDIR) {
2094                /* we are trying to lock foo but we used to
2095                 * have foo/bar which now does not exist;
2096                 * it is normal for the empty directory 'foo'
2097                 * to remain.
2098                 */
2099                ref_file = git_path("%s", orig_refname);
2100                if (remove_empty_directories(ref_file)) {
2101                        last_errno = errno;
2102                        error("there are still refs under '%s'", orig_refname);
2103                        goto error_return;
2104                }
2105                refname = resolve_ref_unsafe(orig_refname, lock->old_sha1, mustexist, &type);
2106        }
2107        if (type_p)
2108            *type_p = type;
2109        if (!refname) {
2110                last_errno = errno;
2111                error("unable to resolve reference %s: %s",
2112                        orig_refname, strerror(errno));
2113                goto error_return;
2114        }
2115        missing = is_null_sha1(lock->old_sha1);
2116        /* When the ref did not exist and we are creating it,
2117         * make sure there is no existing ref that is packed
2118         * whose name begins with our refname, nor a ref whose
2119         * name is a proper prefix of our refname.
2120         */
2121        if (missing &&
2122             !is_refname_available(refname, NULL, get_packed_refs(&ref_cache))) {
2123                last_errno = ENOTDIR;
2124                goto error_return;
2125        }
2126
2127        lock->lk = xcalloc(1, sizeof(struct lock_file));
2128
2129        lflags = 0;
2130        if (flags & REF_NODEREF) {
2131                refname = orig_refname;
2132                lflags |= LOCK_NODEREF;
2133        }
2134        lock->ref_name = xstrdup(refname);
2135        lock->orig_ref_name = xstrdup(orig_refname);
2136        ref_file = git_path("%s", refname);
2137        if (missing)
2138                lock->force_write = 1;
2139        if ((flags & REF_NODEREF) && (type & REF_ISSYMREF))
2140                lock->force_write = 1;
2141
2142 retry:
2143        switch (safe_create_leading_directories(ref_file)) {
2144        case SCLD_OK:
2145                break; /* success */
2146        case SCLD_VANISHED:
2147                if (--attempts_remaining > 0)
2148                        goto retry;
2149                /* fall through */
2150        default:
2151                last_errno = errno;
2152                error("unable to create directory for %s", ref_file);
2153                goto error_return;
2154        }
2155
2156        lock->lock_fd = hold_lock_file_for_update(lock->lk, ref_file, lflags);
2157        if (lock->lock_fd < 0) {
2158                if (errno == ENOENT && --attempts_remaining > 0)
2159                        /*
2160                         * Maybe somebody just deleted one of the
2161                         * directories leading to ref_file.  Try
2162                         * again:
2163                         */
2164                        goto retry;
2165                else
2166                        unable_to_lock_index_die(ref_file, errno);
2167        }
2168        return old_sha1 ? verify_lock(lock, old_sha1, mustexist) : lock;
2169
2170 error_return:
2171        unlock_ref(lock);
2172        errno = last_errno;
2173        return NULL;
2174}
2175
2176struct ref_lock *lock_any_ref_for_update(const char *refname,
2177                                         const unsigned char *old_sha1,
2178                                         int flags, int *type_p)
2179{
2180        if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL))
2181                return NULL;
2182        return lock_ref_sha1_basic(refname, old_sha1, flags, type_p);
2183}
2184
2185/*
2186 * Write an entry to the packed-refs file for the specified refname.
2187 * If peeled is non-NULL, write it as the entry's peeled value.
2188 */
2189static void write_packed_entry(int fd, char *refname, unsigned char *sha1,
2190                               unsigned char *peeled)
2191{
2192        char line[PATH_MAX + 100];
2193        int len;
2194
2195        len = snprintf(line, sizeof(line), "%s %s\n",
2196                       sha1_to_hex(sha1), refname);
2197        /* this should not happen but just being defensive */
2198        if (len > sizeof(line))
2199                die("too long a refname '%s'", refname);
2200        write_or_die(fd, line, len);
2201
2202        if (peeled) {
2203                if (snprintf(line, sizeof(line), "^%s\n",
2204                             sha1_to_hex(peeled)) != PEELED_LINE_LENGTH)
2205                        die("internal error");
2206                write_or_die(fd, line, PEELED_LINE_LENGTH);
2207        }
2208}
2209
2210/*
2211 * An each_ref_entry_fn that writes the entry to a packed-refs file.
2212 */
2213static int write_packed_entry_fn(struct ref_entry *entry, void *cb_data)
2214{
2215        int *fd = cb_data;
2216        enum peel_status peel_status = peel_entry(entry, 0);
2217
2218        if (peel_status != PEEL_PEELED && peel_status != PEEL_NON_TAG)
2219                error("internal error: %s is not a valid packed reference!",
2220                      entry->name);
2221        write_packed_entry(*fd, entry->name, entry->u.value.sha1,
2222                           peel_status == PEEL_PEELED ?
2223                           entry->u.value.peeled : NULL);
2224        return 0;
2225}
2226
2227/* This should return a meaningful errno on failure */
2228int lock_packed_refs(int flags)
2229{
2230        struct packed_ref_cache *packed_ref_cache;
2231
2232        if (hold_lock_file_for_update(&packlock, git_path("packed-refs"), flags) < 0)
2233                return -1;
2234        /*
2235         * Get the current packed-refs while holding the lock.  If the
2236         * packed-refs file has been modified since we last read it,
2237         * this will automatically invalidate the cache and re-read
2238         * the packed-refs file.
2239         */
2240        packed_ref_cache = get_packed_ref_cache(&ref_cache);
2241        packed_ref_cache->lock = &packlock;
2242        /* Increment the reference count to prevent it from being freed: */
2243        acquire_packed_ref_cache(packed_ref_cache);
2244        return 0;
2245}
2246
2247/*
2248 * Commit the packed refs changes.
2249 * On error we must make sure that errno contains a meaningful value.
2250 */
2251int commit_packed_refs(void)
2252{
2253        struct packed_ref_cache *packed_ref_cache =
2254                get_packed_ref_cache(&ref_cache);
2255        int error = 0;
2256        int save_errno = 0;
2257
2258        if (!packed_ref_cache->lock)
2259                die("internal error: packed-refs not locked");
2260        write_or_die(packed_ref_cache->lock->fd,
2261                     PACKED_REFS_HEADER, strlen(PACKED_REFS_HEADER));
2262
2263        do_for_each_entry_in_dir(get_packed_ref_dir(packed_ref_cache),
2264                                 0, write_packed_entry_fn,
2265                                 &packed_ref_cache->lock->fd);
2266        if (commit_lock_file(packed_ref_cache->lock)) {
2267                save_errno = errno;
2268                error = -1;
2269        }
2270        packed_ref_cache->lock = NULL;
2271        release_packed_ref_cache(packed_ref_cache);
2272        errno = save_errno;
2273        return error;
2274}
2275
2276void rollback_packed_refs(void)
2277{
2278        struct packed_ref_cache *packed_ref_cache =
2279                get_packed_ref_cache(&ref_cache);
2280
2281        if (!packed_ref_cache->lock)
2282                die("internal error: packed-refs not locked");
2283        rollback_lock_file(packed_ref_cache->lock);
2284        packed_ref_cache->lock = NULL;
2285        release_packed_ref_cache(packed_ref_cache);
2286        clear_packed_ref_cache(&ref_cache);
2287}
2288
2289struct ref_to_prune {
2290        struct ref_to_prune *next;
2291        unsigned char sha1[20];
2292        char name[FLEX_ARRAY];
2293};
2294
2295struct pack_refs_cb_data {
2296        unsigned int flags;
2297        struct ref_dir *packed_refs;
2298        struct ref_to_prune *ref_to_prune;
2299};
2300
2301/*
2302 * An each_ref_entry_fn that is run over loose references only.  If
2303 * the loose reference can be packed, add an entry in the packed ref
2304 * cache.  If the reference should be pruned, also add it to
2305 * ref_to_prune in the pack_refs_cb_data.
2306 */
2307static int pack_if_possible_fn(struct ref_entry *entry, void *cb_data)
2308{
2309        struct pack_refs_cb_data *cb = cb_data;
2310        enum peel_status peel_status;
2311        struct ref_entry *packed_entry;
2312        int is_tag_ref = starts_with(entry->name, "refs/tags/");
2313
2314        /* ALWAYS pack tags */
2315        if (!(cb->flags & PACK_REFS_ALL) && !is_tag_ref)
2316                return 0;
2317
2318        /* Do not pack symbolic or broken refs: */
2319        if ((entry->flag & REF_ISSYMREF) || !ref_resolves_to_object(entry))
2320                return 0;
2321
2322        /* Add a packed ref cache entry equivalent to the loose entry. */
2323        peel_status = peel_entry(entry, 1);
2324        if (peel_status != PEEL_PEELED && peel_status != PEEL_NON_TAG)
2325                die("internal error peeling reference %s (%s)",
2326                    entry->name, sha1_to_hex(entry->u.value.sha1));
2327        packed_entry = find_ref(cb->packed_refs, entry->name);
2328        if (packed_entry) {
2329                /* Overwrite existing packed entry with info from loose entry */
2330                packed_entry->flag = REF_ISPACKED | REF_KNOWS_PEELED;
2331                hashcpy(packed_entry->u.value.sha1, entry->u.value.sha1);
2332        } else {
2333                packed_entry = create_ref_entry(entry->name, entry->u.value.sha1,
2334                                                REF_ISPACKED | REF_KNOWS_PEELED, 0);
2335                add_ref(cb->packed_refs, packed_entry);
2336        }
2337        hashcpy(packed_entry->u.value.peeled, entry->u.value.peeled);
2338
2339        /* Schedule the loose reference for pruning if requested. */
2340        if ((cb->flags & PACK_REFS_PRUNE)) {
2341                int namelen = strlen(entry->name) + 1;
2342                struct ref_to_prune *n = xcalloc(1, sizeof(*n) + namelen);
2343                hashcpy(n->sha1, entry->u.value.sha1);
2344                strcpy(n->name, entry->name);
2345                n->next = cb->ref_to_prune;
2346                cb->ref_to_prune = n;
2347        }
2348        return 0;
2349}
2350
2351/*
2352 * Remove empty parents, but spare refs/ and immediate subdirs.
2353 * Note: munges *name.
2354 */
2355static void try_remove_empty_parents(char *name)
2356{
2357        char *p, *q;
2358        int i;
2359        p = name;
2360        for (i = 0; i < 2; i++) { /* refs/{heads,tags,...}/ */
2361                while (*p && *p != '/')
2362                        p++;
2363                /* tolerate duplicate slashes; see check_refname_format() */
2364                while (*p == '/')
2365                        p++;
2366        }
2367        for (q = p; *q; q++)
2368                ;
2369        while (1) {
2370                while (q > p && *q != '/')
2371                        q--;
2372                while (q > p && *(q-1) == '/')
2373                        q--;
2374                if (q == p)
2375                        break;
2376                *q = '\0';
2377                if (rmdir(git_path("%s", name)))
2378                        break;
2379        }
2380}
2381
2382/* make sure nobody touched the ref, and unlink */
2383static void prune_ref(struct ref_to_prune *r)
2384{
2385        struct ref_lock *lock;
2386
2387        if (check_refname_format(r->name + 5, 0))
2388                return;
2389
2390        lock = lock_ref_sha1_basic(r->name, r->sha1, 0, NULL);
2391        if (lock) {
2392                unlink_or_warn(git_path("%s", r->name));
2393                unlock_ref(lock);
2394                try_remove_empty_parents(r->name);
2395        }
2396}
2397
2398static void prune_refs(struct ref_to_prune *r)
2399{
2400        while (r) {
2401                prune_ref(r);
2402                r = r->next;
2403        }
2404}
2405
2406int pack_refs(unsigned int flags)
2407{
2408        struct pack_refs_cb_data cbdata;
2409
2410        memset(&cbdata, 0, sizeof(cbdata));
2411        cbdata.flags = flags;
2412
2413        lock_packed_refs(LOCK_DIE_ON_ERROR);
2414        cbdata.packed_refs = get_packed_refs(&ref_cache);
2415
2416        do_for_each_entry_in_dir(get_loose_refs(&ref_cache), 0,
2417                                 pack_if_possible_fn, &cbdata);
2418
2419        if (commit_packed_refs())
2420                die_errno("unable to overwrite old ref-pack file");
2421
2422        prune_refs(cbdata.ref_to_prune);
2423        return 0;
2424}
2425
2426/*
2427 * If entry is no longer needed in packed-refs, add it to the string
2428 * list pointed to by cb_data.  Reasons for deleting entries:
2429 *
2430 * - Entry is broken.
2431 * - Entry is overridden by a loose ref.
2432 * - Entry does not point at a valid object.
2433 *
2434 * In the first and third cases, also emit an error message because these
2435 * are indications of repository corruption.
2436 */
2437static int curate_packed_ref_fn(struct ref_entry *entry, void *cb_data)
2438{
2439        struct string_list *refs_to_delete = cb_data;
2440
2441        if (entry->flag & REF_ISBROKEN) {
2442                /* This shouldn't happen to packed refs. */
2443                error("%s is broken!", entry->name);
2444                string_list_append(refs_to_delete, entry->name);
2445                return 0;
2446        }
2447        if (!has_sha1_file(entry->u.value.sha1)) {
2448                unsigned char sha1[20];
2449                int flags;
2450
2451                if (read_ref_full(entry->name, sha1, 0, &flags))
2452                        /* We should at least have found the packed ref. */
2453                        die("Internal error");
2454                if ((flags & REF_ISSYMREF) || !(flags & REF_ISPACKED)) {
2455                        /*
2456                         * This packed reference is overridden by a
2457                         * loose reference, so it is OK that its value
2458                         * is no longer valid; for example, it might
2459                         * refer to an object that has been garbage
2460                         * collected.  For this purpose we don't even
2461                         * care whether the loose reference itself is
2462                         * invalid, broken, symbolic, etc.  Silently
2463                         * remove the packed reference.
2464                         */
2465                        string_list_append(refs_to_delete, entry->name);
2466                        return 0;
2467                }
2468                /*
2469                 * There is no overriding loose reference, so the fact
2470                 * that this reference doesn't refer to a valid object
2471                 * indicates some kind of repository corruption.
2472                 * Report the problem, then omit the reference from
2473                 * the output.
2474                 */
2475                error("%s does not point to a valid object!", entry->name);
2476                string_list_append(refs_to_delete, entry->name);
2477                return 0;
2478        }
2479
2480        return 0;
2481}
2482
2483int repack_without_refs(const char **refnames, int n, struct strbuf *err)
2484{
2485        struct ref_dir *packed;
2486        struct string_list refs_to_delete = STRING_LIST_INIT_DUP;
2487        struct string_list_item *ref_to_delete;
2488        int i, ret, removed = 0;
2489
2490        /* Look for a packed ref */
2491        for (i = 0; i < n; i++)
2492                if (get_packed_ref(refnames[i]))
2493                        break;
2494
2495        /* Avoid locking if we have nothing to do */
2496        if (i == n)
2497                return 0; /* no refname exists in packed refs */
2498
2499        if (lock_packed_refs(0)) {
2500                if (err) {
2501                        unable_to_lock_message(git_path("packed-refs"), errno,
2502                                               err);
2503                        return -1;
2504                }
2505                unable_to_lock_error(git_path("packed-refs"), errno);
2506                return error("cannot delete '%s' from packed refs", refnames[i]);
2507        }
2508        packed = get_packed_refs(&ref_cache);
2509
2510        /* Remove refnames from the cache */
2511        for (i = 0; i < n; i++)
2512                if (remove_entry(packed, refnames[i]) != -1)
2513                        removed = 1;
2514        if (!removed) {
2515                /*
2516                 * All packed entries disappeared while we were
2517                 * acquiring the lock.
2518                 */
2519                rollback_packed_refs();
2520                return 0;
2521        }
2522
2523        /* Remove any other accumulated cruft */
2524        do_for_each_entry_in_dir(packed, 0, curate_packed_ref_fn, &refs_to_delete);
2525        for_each_string_list_item(ref_to_delete, &refs_to_delete) {
2526                if (remove_entry(packed, ref_to_delete->string) == -1)
2527                        die("internal error");
2528        }
2529
2530        /* Write what remains */
2531        ret = commit_packed_refs();
2532        if (ret && err)
2533                strbuf_addf(err, "unable to overwrite old ref-pack file: %s",
2534                            strerror(errno));
2535        return ret;
2536}
2537
2538static int repack_without_ref(const char *refname)
2539{
2540        return repack_without_refs(&refname, 1, NULL);
2541}
2542
2543static int delete_ref_loose(struct ref_lock *lock, int flag)
2544{
2545        if (!(flag & REF_ISPACKED) || flag & REF_ISSYMREF) {
2546                /* loose */
2547                int err, i = strlen(lock->lk->filename) - 5; /* .lock */
2548
2549                lock->lk->filename[i] = 0;
2550                err = unlink_or_warn(lock->lk->filename);
2551                lock->lk->filename[i] = '.';
2552                if (err && errno != ENOENT)
2553                        return 1;
2554        }
2555        return 0;
2556}
2557
2558int delete_ref(const char *refname, const unsigned char *sha1, int delopt)
2559{
2560        struct ref_lock *lock;
2561        int ret = 0, flag = 0;
2562
2563        lock = lock_ref_sha1_basic(refname, sha1, delopt, &flag);
2564        if (!lock)
2565                return 1;
2566        ret |= delete_ref_loose(lock, flag);
2567
2568        /* removing the loose one could have resurrected an earlier
2569         * packed one.  Also, if it was not loose we need to repack
2570         * without it.
2571         */
2572        ret |= repack_without_ref(lock->ref_name);
2573
2574        unlink_or_warn(git_path("logs/%s", lock->ref_name));
2575        clear_loose_ref_cache(&ref_cache);
2576        unlock_ref(lock);
2577        return ret;
2578}
2579
2580/*
2581 * People using contrib's git-new-workdir have .git/logs/refs ->
2582 * /some/other/path/.git/logs/refs, and that may live on another device.
2583 *
2584 * IOW, to avoid cross device rename errors, the temporary renamed log must
2585 * live into logs/refs.
2586 */
2587#define TMP_RENAMED_LOG  "logs/refs/.tmp-renamed-log"
2588
2589static int rename_tmp_log(const char *newrefname)
2590{
2591        int attempts_remaining = 4;
2592
2593 retry:
2594        switch (safe_create_leading_directories(git_path("logs/%s", newrefname))) {
2595        case SCLD_OK:
2596                break; /* success */
2597        case SCLD_VANISHED:
2598                if (--attempts_remaining > 0)
2599                        goto retry;
2600                /* fall through */
2601        default:
2602                error("unable to create directory for %s", newrefname);
2603                return -1;
2604        }
2605
2606        if (rename(git_path(TMP_RENAMED_LOG), git_path("logs/%s", newrefname))) {
2607                if ((errno==EISDIR || errno==ENOTDIR) && --attempts_remaining > 0) {
2608                        /*
2609                         * rename(a, b) when b is an existing
2610                         * directory ought to result in ISDIR, but
2611                         * Solaris 5.8 gives ENOTDIR.  Sheesh.
2612                         */
2613                        if (remove_empty_directories(git_path("logs/%s", newrefname))) {
2614                                error("Directory not empty: logs/%s", newrefname);
2615                                return -1;
2616                        }
2617                        goto retry;
2618                } else if (errno == ENOENT && --attempts_remaining > 0) {
2619                        /*
2620                         * Maybe another process just deleted one of
2621                         * the directories in the path to newrefname.
2622                         * Try again from the beginning.
2623                         */
2624                        goto retry;
2625                } else {
2626                        error("unable to move logfile "TMP_RENAMED_LOG" to logs/%s: %s",
2627                                newrefname, strerror(errno));
2628                        return -1;
2629                }
2630        }
2631        return 0;
2632}
2633
2634int rename_ref(const char *oldrefname, const char *newrefname, const char *logmsg)
2635{
2636        unsigned char sha1[20], orig_sha1[20];
2637        int flag = 0, logmoved = 0;
2638        struct ref_lock *lock;
2639        struct stat loginfo;
2640        int log = !lstat(git_path("logs/%s", oldrefname), &loginfo);
2641        const char *symref = NULL;
2642
2643        if (log && S_ISLNK(loginfo.st_mode))
2644                return error("reflog for %s is a symlink", oldrefname);
2645
2646        symref = resolve_ref_unsafe(oldrefname, orig_sha1, 1, &flag);
2647        if (flag & REF_ISSYMREF)
2648                return error("refname %s is a symbolic ref, renaming it is not supported",
2649                        oldrefname);
2650        if (!symref)
2651                return error("refname %s not found", oldrefname);
2652
2653        if (!is_refname_available(newrefname, oldrefname, get_packed_refs(&ref_cache)))
2654                return 1;
2655
2656        if (!is_refname_available(newrefname, oldrefname, get_loose_refs(&ref_cache)))
2657                return 1;
2658
2659        if (log && rename(git_path("logs/%s", oldrefname), git_path(TMP_RENAMED_LOG)))
2660                return error("unable to move logfile logs/%s to "TMP_RENAMED_LOG": %s",
2661                        oldrefname, strerror(errno));
2662
2663        if (delete_ref(oldrefname, orig_sha1, REF_NODEREF)) {
2664                error("unable to delete old %s", oldrefname);
2665                goto rollback;
2666        }
2667
2668        if (!read_ref_full(newrefname, sha1, 1, &flag) &&
2669            delete_ref(newrefname, sha1, REF_NODEREF)) {
2670                if (errno==EISDIR) {
2671                        if (remove_empty_directories(git_path("%s", newrefname))) {
2672                                error("Directory not empty: %s", newrefname);
2673                                goto rollback;
2674                        }
2675                } else {
2676                        error("unable to delete existing %s", newrefname);
2677                        goto rollback;
2678                }
2679        }
2680
2681        if (log && rename_tmp_log(newrefname))
2682                goto rollback;
2683
2684        logmoved = log;
2685
2686        lock = lock_ref_sha1_basic(newrefname, NULL, 0, NULL);
2687        if (!lock) {
2688                error("unable to lock %s for update", newrefname);
2689                goto rollback;
2690        }
2691        lock->force_write = 1;
2692        hashcpy(lock->old_sha1, orig_sha1);
2693        if (write_ref_sha1(lock, orig_sha1, logmsg)) {
2694                error("unable to write current sha1 into %s", newrefname);
2695                goto rollback;
2696        }
2697
2698        return 0;
2699
2700 rollback:
2701        lock = lock_ref_sha1_basic(oldrefname, NULL, 0, NULL);
2702        if (!lock) {
2703                error("unable to lock %s for rollback", oldrefname);
2704                goto rollbacklog;
2705        }
2706
2707        lock->force_write = 1;
2708        flag = log_all_ref_updates;
2709        log_all_ref_updates = 0;
2710        if (write_ref_sha1(lock, orig_sha1, NULL))
2711                error("unable to write current sha1 into %s", oldrefname);
2712        log_all_ref_updates = flag;
2713
2714 rollbacklog:
2715        if (logmoved && rename(git_path("logs/%s", newrefname), git_path("logs/%s", oldrefname)))
2716                error("unable to restore logfile %s from %s: %s",
2717                        oldrefname, newrefname, strerror(errno));
2718        if (!logmoved && log &&
2719            rename(git_path(TMP_RENAMED_LOG), git_path("logs/%s", oldrefname)))
2720                error("unable to restore logfile %s from "TMP_RENAMED_LOG": %s",
2721                        oldrefname, strerror(errno));
2722
2723        return 1;
2724}
2725
2726int close_ref(struct ref_lock *lock)
2727{
2728        if (close_lock_file(lock->lk))
2729                return -1;
2730        lock->lock_fd = -1;
2731        return 0;
2732}
2733
2734int commit_ref(struct ref_lock *lock)
2735{
2736        if (commit_lock_file(lock->lk))
2737                return -1;
2738        lock->lock_fd = -1;
2739        return 0;
2740}
2741
2742void unlock_ref(struct ref_lock *lock)
2743{
2744        /* Do not free lock->lk -- atexit() still looks at them */
2745        if (lock->lk)
2746                rollback_lock_file(lock->lk);
2747        free(lock->ref_name);
2748        free(lock->orig_ref_name);
2749        free(lock);
2750}
2751
2752/*
2753 * copy the reflog message msg to buf, which has been allocated sufficiently
2754 * large, while cleaning up the whitespaces.  Especially, convert LF to space,
2755 * because reflog file is one line per entry.
2756 */
2757static int copy_msg(char *buf, const char *msg)
2758{
2759        char *cp = buf;
2760        char c;
2761        int wasspace = 1;
2762
2763        *cp++ = '\t';
2764        while ((c = *msg++)) {
2765                if (wasspace && isspace(c))
2766                        continue;
2767                wasspace = isspace(c);
2768                if (wasspace)
2769                        c = ' ';
2770                *cp++ = c;
2771        }
2772        while (buf < cp && isspace(cp[-1]))
2773                cp--;
2774        *cp++ = '\n';
2775        return cp - buf;
2776}
2777
2778/* This function must set a meaningful errno on failure */
2779int log_ref_setup(const char *refname, char *logfile, int bufsize)
2780{
2781        int logfd, oflags = O_APPEND | O_WRONLY;
2782
2783        git_snpath(logfile, bufsize, "logs/%s", refname);
2784        if (log_all_ref_updates &&
2785            (starts_with(refname, "refs/heads/") ||
2786             starts_with(refname, "refs/remotes/") ||
2787             starts_with(refname, "refs/notes/") ||
2788             !strcmp(refname, "HEAD"))) {
2789                if (safe_create_leading_directories(logfile) < 0) {
2790                        int save_errno = errno;
2791                        error("unable to create directory for %s", logfile);
2792                        errno = save_errno;
2793                        return -1;
2794                }
2795                oflags |= O_CREAT;
2796        }
2797
2798        logfd = open(logfile, oflags, 0666);
2799        if (logfd < 0) {
2800                if (!(oflags & O_CREAT) && errno == ENOENT)
2801                        return 0;
2802
2803                if ((oflags & O_CREAT) && errno == EISDIR) {
2804                        if (remove_empty_directories(logfile)) {
2805                                int save_errno = errno;
2806                                error("There are still logs under '%s'",
2807                                      logfile);
2808                                errno = save_errno;
2809                                return -1;
2810                        }
2811                        logfd = open(logfile, oflags, 0666);
2812                }
2813
2814                if (logfd < 0) {
2815                        int save_errno = errno;
2816                        error("Unable to append to %s: %s", logfile,
2817                              strerror(errno));
2818                        errno = save_errno;
2819                        return -1;
2820                }
2821        }
2822
2823        adjust_shared_perm(logfile);
2824        close(logfd);
2825        return 0;
2826}
2827
2828static int log_ref_write(const char *refname, const unsigned char *old_sha1,
2829                         const unsigned char *new_sha1, const char *msg)
2830{
2831        int logfd, result, written, oflags = O_APPEND | O_WRONLY;
2832        unsigned maxlen, len;
2833        int msglen;
2834        char log_file[PATH_MAX];
2835        char *logrec;
2836        const char *committer;
2837
2838        if (log_all_ref_updates < 0)
2839                log_all_ref_updates = !is_bare_repository();
2840
2841        result = log_ref_setup(refname, log_file, sizeof(log_file));
2842        if (result)
2843                return result;
2844
2845        logfd = open(log_file, oflags);
2846        if (logfd < 0)
2847                return 0;
2848        msglen = msg ? strlen(msg) : 0;
2849        committer = git_committer_info(0);
2850        maxlen = strlen(committer) + msglen + 100;
2851        logrec = xmalloc(maxlen);
2852        len = sprintf(logrec, "%s %s %s\n",
2853                      sha1_to_hex(old_sha1),
2854                      sha1_to_hex(new_sha1),
2855                      committer);
2856        if (msglen)
2857                len += copy_msg(logrec + len - 1, msg) - 1;
2858        written = len <= maxlen ? write_in_full(logfd, logrec, len) : -1;
2859        free(logrec);
2860        if (written != len) {
2861                int save_errno = errno;
2862                close(logfd);
2863                error("Unable to append to %s", log_file);
2864                errno = save_errno;
2865                return -1;
2866        }
2867        if (close(logfd)) {
2868                int save_errno = errno;
2869                error("Unable to append to %s", log_file);
2870                errno = save_errno;
2871                return -1;
2872        }
2873        return 0;
2874}
2875
2876static int is_branch(const char *refname)
2877{
2878        return !strcmp(refname, "HEAD") || starts_with(refname, "refs/heads/");
2879}
2880
2881/* This function must return a meaningful errno */
2882int write_ref_sha1(struct ref_lock *lock,
2883        const unsigned char *sha1, const char *logmsg)
2884{
2885        static char term = '\n';
2886        struct object *o;
2887
2888        if (!lock) {
2889                errno = EINVAL;
2890                return -1;
2891        }
2892        if (!lock->force_write && !hashcmp(lock->old_sha1, sha1)) {
2893                unlock_ref(lock);
2894                return 0;
2895        }
2896        o = parse_object(sha1);
2897        if (!o) {
2898                error("Trying to write ref %s with nonexistent object %s",
2899                        lock->ref_name, sha1_to_hex(sha1));
2900                unlock_ref(lock);
2901                errno = EINVAL;
2902                return -1;
2903        }
2904        if (o->type != OBJ_COMMIT && is_branch(lock->ref_name)) {
2905                error("Trying to write non-commit object %s to branch %s",
2906                        sha1_to_hex(sha1), lock->ref_name);
2907                unlock_ref(lock);
2908                errno = EINVAL;
2909                return -1;
2910        }
2911        if (write_in_full(lock->lock_fd, sha1_to_hex(sha1), 40) != 40 ||
2912            write_in_full(lock->lock_fd, &term, 1) != 1 ||
2913            close_ref(lock) < 0) {
2914                int save_errno = errno;
2915                error("Couldn't write %s", lock->lk->filename);
2916                unlock_ref(lock);
2917                errno = save_errno;
2918                return -1;
2919        }
2920        clear_loose_ref_cache(&ref_cache);
2921        if (log_ref_write(lock->ref_name, lock->old_sha1, sha1, logmsg) < 0 ||
2922            (strcmp(lock->ref_name, lock->orig_ref_name) &&
2923             log_ref_write(lock->orig_ref_name, lock->old_sha1, sha1, logmsg) < 0)) {
2924                unlock_ref(lock);
2925                return -1;
2926        }
2927        if (strcmp(lock->orig_ref_name, "HEAD") != 0) {
2928                /*
2929                 * Special hack: If a branch is updated directly and HEAD
2930                 * points to it (may happen on the remote side of a push
2931                 * for example) then logically the HEAD reflog should be
2932                 * updated too.
2933                 * A generic solution implies reverse symref information,
2934                 * but finding all symrefs pointing to the given branch
2935                 * would be rather costly for this rare event (the direct
2936                 * update of a branch) to be worth it.  So let's cheat and
2937                 * check with HEAD only which should cover 99% of all usage
2938                 * scenarios (even 100% of the default ones).
2939                 */
2940                unsigned char head_sha1[20];
2941                int head_flag;
2942                const char *head_ref;
2943                head_ref = resolve_ref_unsafe("HEAD", head_sha1, 1, &head_flag);
2944                if (head_ref && (head_flag & REF_ISSYMREF) &&
2945                    !strcmp(head_ref, lock->ref_name))
2946                        log_ref_write("HEAD", lock->old_sha1, sha1, logmsg);
2947        }
2948        if (commit_ref(lock)) {
2949                error("Couldn't set %s", lock->ref_name);
2950                unlock_ref(lock);
2951                return -1;
2952        }
2953        unlock_ref(lock);
2954        return 0;
2955}
2956
2957int create_symref(const char *ref_target, const char *refs_heads_master,
2958                  const char *logmsg)
2959{
2960        const char *lockpath;
2961        char ref[1000];
2962        int fd, len, written;
2963        char *git_HEAD = git_pathdup("%s", ref_target);
2964        unsigned char old_sha1[20], new_sha1[20];
2965
2966        if (logmsg && read_ref(ref_target, old_sha1))
2967                hashclr(old_sha1);
2968
2969        if (safe_create_leading_directories(git_HEAD) < 0)
2970                return error("unable to create directory for %s", git_HEAD);
2971
2972#ifndef NO_SYMLINK_HEAD
2973        if (prefer_symlink_refs) {
2974                unlink(git_HEAD);
2975                if (!symlink(refs_heads_master, git_HEAD))
2976                        goto done;
2977                fprintf(stderr, "no symlink - falling back to symbolic ref\n");
2978        }
2979#endif
2980
2981        len = snprintf(ref, sizeof(ref), "ref: %s\n", refs_heads_master);
2982        if (sizeof(ref) <= len) {
2983                error("refname too long: %s", refs_heads_master);
2984                goto error_free_return;
2985        }
2986        lockpath = mkpath("%s.lock", git_HEAD);
2987        fd = open(lockpath, O_CREAT | O_EXCL | O_WRONLY, 0666);
2988        if (fd < 0) {
2989                error("Unable to open %s for writing", lockpath);
2990                goto error_free_return;
2991        }
2992        written = write_in_full(fd, ref, len);
2993        if (close(fd) != 0 || written != len) {
2994                error("Unable to write to %s", lockpath);
2995                goto error_unlink_return;
2996        }
2997        if (rename(lockpath, git_HEAD) < 0) {
2998                error("Unable to create %s", git_HEAD);
2999                goto error_unlink_return;
3000        }
3001        if (adjust_shared_perm(git_HEAD)) {
3002                error("Unable to fix permissions on %s", lockpath);
3003        error_unlink_return:
3004                unlink_or_warn(lockpath);
3005        error_free_return:
3006                free(git_HEAD);
3007                return -1;
3008        }
3009
3010#ifndef NO_SYMLINK_HEAD
3011        done:
3012#endif
3013        if (logmsg && !read_ref(refs_heads_master, new_sha1))
3014                log_ref_write(ref_target, old_sha1, new_sha1, logmsg);
3015
3016        free(git_HEAD);
3017        return 0;
3018}
3019
3020struct read_ref_at_cb {
3021        const char *refname;
3022        unsigned long at_time;
3023        int cnt;
3024        int reccnt;
3025        unsigned char *sha1;
3026        int found_it;
3027
3028        unsigned char osha1[20];
3029        unsigned char nsha1[20];
3030        int tz;
3031        unsigned long date;
3032        char **msg;
3033        unsigned long *cutoff_time;
3034        int *cutoff_tz;
3035        int *cutoff_cnt;
3036};
3037
3038static int read_ref_at_ent(unsigned char *osha1, unsigned char *nsha1,
3039                const char *email, unsigned long timestamp, int tz,
3040                const char *message, void *cb_data)
3041{
3042        struct read_ref_at_cb *cb = cb_data;
3043
3044        cb->reccnt++;
3045        cb->tz = tz;
3046        cb->date = timestamp;
3047
3048        if (timestamp <= cb->at_time || cb->cnt == 0) {
3049                if (cb->msg)
3050                        *cb->msg = xstrdup(message);
3051                if (cb->cutoff_time)
3052                        *cb->cutoff_time = timestamp;
3053                if (cb->cutoff_tz)
3054                        *cb->cutoff_tz = tz;
3055                if (cb->cutoff_cnt)
3056                        *cb->cutoff_cnt = cb->reccnt - 1;
3057                /*
3058                 * we have not yet updated cb->[n|o]sha1 so they still
3059                 * hold the values for the previous record.
3060                 */
3061                if (!is_null_sha1(cb->osha1)) {
3062                        hashcpy(cb->sha1, nsha1);
3063                        if (hashcmp(cb->osha1, nsha1))
3064                                warning("Log for ref %s has gap after %s.",
3065                                        cb->refname, show_date(cb->date, cb->tz, DATE_RFC2822));
3066                }
3067                else if (cb->date == cb->at_time)
3068                        hashcpy(cb->sha1, nsha1);
3069                else if (hashcmp(nsha1, cb->sha1))
3070                        warning("Log for ref %s unexpectedly ended on %s.",
3071                                cb->refname, show_date(cb->date, cb->tz,
3072                                                   DATE_RFC2822));
3073                hashcpy(cb->osha1, osha1);
3074                hashcpy(cb->nsha1, nsha1);
3075                cb->found_it = 1;
3076                return 1;
3077        }
3078        hashcpy(cb->osha1, osha1);
3079        hashcpy(cb->nsha1, nsha1);
3080        if (cb->cnt > 0)
3081                cb->cnt--;
3082        return 0;
3083}
3084
3085static int read_ref_at_ent_oldest(unsigned char *osha1, unsigned char *nsha1,
3086                                  const char *email, unsigned long timestamp,
3087                                  int tz, const char *message, void *cb_data)
3088{
3089        struct read_ref_at_cb *cb = cb_data;
3090
3091        if (cb->msg)
3092                *cb->msg = xstrdup(message);
3093        if (cb->cutoff_time)
3094                *cb->cutoff_time = timestamp;
3095        if (cb->cutoff_tz)
3096                *cb->cutoff_tz = tz;
3097        if (cb->cutoff_cnt)
3098                *cb->cutoff_cnt = cb->reccnt;
3099        hashcpy(cb->sha1, osha1);
3100        if (is_null_sha1(cb->sha1))
3101                hashcpy(cb->sha1, nsha1);
3102        /* We just want the first entry */
3103        return 1;
3104}
3105
3106int read_ref_at(const char *refname, unsigned long at_time, int cnt,
3107                unsigned char *sha1, char **msg,
3108                unsigned long *cutoff_time, int *cutoff_tz, int *cutoff_cnt)
3109{
3110        struct read_ref_at_cb cb;
3111
3112        memset(&cb, 0, sizeof(cb));
3113        cb.refname = refname;
3114        cb.at_time = at_time;
3115        cb.cnt = cnt;
3116        cb.msg = msg;
3117        cb.cutoff_time = cutoff_time;
3118        cb.cutoff_tz = cutoff_tz;
3119        cb.cutoff_cnt = cutoff_cnt;
3120        cb.sha1 = sha1;
3121
3122        for_each_reflog_ent_reverse(refname, read_ref_at_ent, &cb);
3123
3124        if (!cb.reccnt)
3125                die("Log for %s is empty.", refname);
3126        if (cb.found_it)
3127                return 0;
3128
3129        for_each_reflog_ent(refname, read_ref_at_ent_oldest, &cb);
3130
3131        return 1;
3132}
3133
3134int reflog_exists(const char *refname)
3135{
3136        struct stat st;
3137
3138        return !lstat(git_path("logs/%s", refname), &st) &&
3139                S_ISREG(st.st_mode);
3140}
3141
3142int delete_reflog(const char *refname)
3143{
3144        return remove_path(git_path("logs/%s", refname));
3145}
3146
3147static int show_one_reflog_ent(struct strbuf *sb, each_reflog_ent_fn fn, void *cb_data)
3148{
3149        unsigned char osha1[20], nsha1[20];
3150        char *email_end, *message;
3151        unsigned long timestamp;
3152        int tz;
3153
3154        /* old SP new SP name <email> SP time TAB msg LF */
3155        if (sb->len < 83 || sb->buf[sb->len - 1] != '\n' ||
3156            get_sha1_hex(sb->buf, osha1) || sb->buf[40] != ' ' ||
3157            get_sha1_hex(sb->buf + 41, nsha1) || sb->buf[81] != ' ' ||
3158            !(email_end = strchr(sb->buf + 82, '>')) ||
3159            email_end[1] != ' ' ||
3160            !(timestamp = strtoul(email_end + 2, &message, 10)) ||
3161            !message || message[0] != ' ' ||
3162            (message[1] != '+' && message[1] != '-') ||
3163            !isdigit(message[2]) || !isdigit(message[3]) ||
3164            !isdigit(message[4]) || !isdigit(message[5]))
3165                return 0; /* corrupt? */
3166        email_end[1] = '\0';
3167        tz = strtol(message + 1, NULL, 10);
3168        if (message[6] != '\t')
3169                message += 6;
3170        else
3171                message += 7;
3172        return fn(osha1, nsha1, sb->buf + 82, timestamp, tz, message, cb_data);
3173}
3174
3175static char *find_beginning_of_line(char *bob, char *scan)
3176{
3177        while (bob < scan && *(--scan) != '\n')
3178                ; /* keep scanning backwards */
3179        /*
3180         * Return either beginning of the buffer, or LF at the end of
3181         * the previous line.
3182         */
3183        return scan;
3184}
3185
3186int for_each_reflog_ent_reverse(const char *refname, each_reflog_ent_fn fn, void *cb_data)
3187{
3188        struct strbuf sb = STRBUF_INIT;
3189        FILE *logfp;
3190        long pos;
3191        int ret = 0, at_tail = 1;
3192
3193        logfp = fopen(git_path("logs/%s", refname), "r");
3194        if (!logfp)
3195                return -1;
3196
3197        /* Jump to the end */
3198        if (fseek(logfp, 0, SEEK_END) < 0)
3199                return error("cannot seek back reflog for %s: %s",
3200                             refname, strerror(errno));
3201        pos = ftell(logfp);
3202        while (!ret && 0 < pos) {
3203                int cnt;
3204                size_t nread;
3205                char buf[BUFSIZ];
3206                char *endp, *scanp;
3207
3208                /* Fill next block from the end */
3209                cnt = (sizeof(buf) < pos) ? sizeof(buf) : pos;
3210                if (fseek(logfp, pos - cnt, SEEK_SET))
3211                        return error("cannot seek back reflog for %s: %s",
3212                                     refname, strerror(errno));
3213                nread = fread(buf, cnt, 1, logfp);
3214                if (nread != 1)
3215                        return error("cannot read %d bytes from reflog for %s: %s",
3216                                     cnt, refname, strerror(errno));
3217                pos -= cnt;
3218
3219                scanp = endp = buf + cnt;
3220                if (at_tail && scanp[-1] == '\n')
3221                        /* Looking at the final LF at the end of the file */
3222                        scanp--;
3223                at_tail = 0;
3224
3225                while (buf < scanp) {
3226                        /*
3227                         * terminating LF of the previous line, or the beginning
3228                         * of the buffer.
3229                         */
3230                        char *bp;
3231
3232                        bp = find_beginning_of_line(buf, scanp);
3233
3234                        if (*bp != '\n') {
3235                                strbuf_splice(&sb, 0, 0, buf, endp - buf);
3236                                if (pos)
3237                                        break; /* need to fill another block */
3238                                scanp = buf - 1; /* leave loop */
3239                        } else {
3240                                /*
3241                                 * (bp + 1) thru endp is the beginning of the
3242                                 * current line we have in sb
3243                                 */
3244                                strbuf_splice(&sb, 0, 0, bp + 1, endp - (bp + 1));
3245                                scanp = bp;
3246                                endp = bp + 1;
3247                        }
3248                        ret = show_one_reflog_ent(&sb, fn, cb_data);
3249                        strbuf_reset(&sb);
3250                        if (ret)
3251                                break;
3252                }
3253
3254        }
3255        if (!ret && sb.len)
3256                ret = show_one_reflog_ent(&sb, fn, cb_data);
3257
3258        fclose(logfp);
3259        strbuf_release(&sb);
3260        return ret;
3261}
3262
3263int for_each_reflog_ent(const char *refname, each_reflog_ent_fn fn, void *cb_data)
3264{
3265        FILE *logfp;
3266        struct strbuf sb = STRBUF_INIT;
3267        int ret = 0;
3268
3269        logfp = fopen(git_path("logs/%s", refname), "r");
3270        if (!logfp)
3271                return -1;
3272
3273        while (!ret && !strbuf_getwholeline(&sb, logfp, '\n'))
3274                ret = show_one_reflog_ent(&sb, fn, cb_data);
3275        fclose(logfp);
3276        strbuf_release(&sb);
3277        return ret;
3278}
3279/*
3280 * Call fn for each reflog in the namespace indicated by name.  name
3281 * must be empty or end with '/'.  Name will be used as a scratch
3282 * space, but its contents will be restored before return.
3283 */
3284static int do_for_each_reflog(struct strbuf *name, each_ref_fn fn, void *cb_data)
3285{
3286        DIR *d = opendir(git_path("logs/%s", name->buf));
3287        int retval = 0;
3288        struct dirent *de;
3289        int oldlen = name->len;
3290
3291        if (!d)
3292                return name->len ? errno : 0;
3293
3294        while ((de = readdir(d)) != NULL) {
3295                struct stat st;
3296
3297                if (de->d_name[0] == '.')
3298                        continue;
3299                if (has_extension(de->d_name, ".lock"))
3300                        continue;
3301                strbuf_addstr(name, de->d_name);
3302                if (stat(git_path("logs/%s", name->buf), &st) < 0) {
3303                        ; /* silently ignore */
3304                } else {
3305                        if (S_ISDIR(st.st_mode)) {
3306                                strbuf_addch(name, '/');
3307                                retval = do_for_each_reflog(name, fn, cb_data);
3308                        } else {
3309                                unsigned char sha1[20];
3310                                if (read_ref_full(name->buf, sha1, 0, NULL))
3311                                        retval = error("bad ref for %s", name->buf);
3312                                else
3313                                        retval = fn(name->buf, sha1, 0, cb_data);
3314                        }
3315                        if (retval)
3316                                break;
3317                }
3318                strbuf_setlen(name, oldlen);
3319        }
3320        closedir(d);
3321        return retval;
3322}
3323
3324int for_each_reflog(each_ref_fn fn, void *cb_data)
3325{
3326        int retval;
3327        struct strbuf name;
3328        strbuf_init(&name, PATH_MAX);
3329        retval = do_for_each_reflog(&name, fn, cb_data);
3330        strbuf_release(&name);
3331        return retval;
3332}
3333
3334/**
3335 * Information needed for a single ref update.  Set new_sha1 to the
3336 * new value or to zero to delete the ref.  To check the old value
3337 * while locking the ref, set have_old to 1 and set old_sha1 to the
3338 * value or to zero to ensure the ref does not exist before update.
3339 */
3340struct ref_update {
3341        unsigned char new_sha1[20];
3342        unsigned char old_sha1[20];
3343        int flags; /* REF_NODEREF? */
3344        int have_old; /* 1 if old_sha1 is valid, 0 otherwise */
3345        struct ref_lock *lock;
3346        int type;
3347        const char refname[FLEX_ARRAY];
3348};
3349
3350/*
3351 * Transaction states.
3352 * OPEN:   The transaction is in a valid state and can accept new updates.
3353 *         An OPEN transaction can be committed.
3354 * CLOSED: A closed transaction is no longer active and no other operations
3355 *         than free can be used on it in this state.
3356 *         A transaction can either become closed by successfully committing
3357 *         an active transaction or if there is a failure while building
3358 *         the transaction thus rendering it failed/inactive.
3359 */
3360enum ref_transaction_state {
3361        REF_TRANSACTION_OPEN   = 0,
3362        REF_TRANSACTION_CLOSED = 1
3363};
3364
3365/*
3366 * Data structure for holding a reference transaction, which can
3367 * consist of checks and updates to multiple references, carried out
3368 * as atomically as possible.  This structure is opaque to callers.
3369 */
3370struct ref_transaction {
3371        struct ref_update **updates;
3372        size_t alloc;
3373        size_t nr;
3374        enum ref_transaction_state state;
3375};
3376
3377struct ref_transaction *ref_transaction_begin(struct strbuf *err)
3378{
3379        return xcalloc(1, sizeof(struct ref_transaction));
3380}
3381
3382void ref_transaction_free(struct ref_transaction *transaction)
3383{
3384        int i;
3385
3386        if (!transaction)
3387                return;
3388
3389        for (i = 0; i < transaction->nr; i++)
3390                free(transaction->updates[i]);
3391
3392        free(transaction->updates);
3393        free(transaction);
3394}
3395
3396static struct ref_update *add_update(struct ref_transaction *transaction,
3397                                     const char *refname)
3398{
3399        size_t len = strlen(refname);
3400        struct ref_update *update = xcalloc(1, sizeof(*update) + len + 1);
3401
3402        strcpy((char *)update->refname, refname);
3403        ALLOC_GROW(transaction->updates, transaction->nr + 1, transaction->alloc);
3404        transaction->updates[transaction->nr++] = update;
3405        return update;
3406}
3407
3408int ref_transaction_update(struct ref_transaction *transaction,
3409                           const char *refname,
3410                           const unsigned char *new_sha1,
3411                           const unsigned char *old_sha1,
3412                           int flags, int have_old,
3413                           struct strbuf *err)
3414{
3415        struct ref_update *update;
3416
3417        if (transaction->state != REF_TRANSACTION_OPEN)
3418                die("BUG: update called for transaction that is not open");
3419
3420        if (have_old && !old_sha1)
3421                die("BUG: have_old is true but old_sha1 is NULL");
3422
3423        update = add_update(transaction, refname);
3424        hashcpy(update->new_sha1, new_sha1);
3425        update->flags = flags;
3426        update->have_old = have_old;
3427        if (have_old)
3428                hashcpy(update->old_sha1, old_sha1);
3429        return 0;
3430}
3431
3432int ref_transaction_create(struct ref_transaction *transaction,
3433                           const char *refname,
3434                           const unsigned char *new_sha1,
3435                           int flags,
3436                           struct strbuf *err)
3437{
3438        struct ref_update *update;
3439
3440        if (transaction->state != REF_TRANSACTION_OPEN)
3441                die("BUG: create called for transaction that is not open");
3442
3443        if (!new_sha1 || is_null_sha1(new_sha1))
3444                die("BUG: create ref with null new_sha1");
3445
3446        update = add_update(transaction, refname);
3447
3448        hashcpy(update->new_sha1, new_sha1);
3449        hashclr(update->old_sha1);
3450        update->flags = flags;
3451        update->have_old = 1;
3452        return 0;
3453}
3454
3455int ref_transaction_delete(struct ref_transaction *transaction,
3456                           const char *refname,
3457                           const unsigned char *old_sha1,
3458                           int flags, int have_old,
3459                           struct strbuf *err)
3460{
3461        struct ref_update *update;
3462
3463        if (transaction->state != REF_TRANSACTION_OPEN)
3464                die("BUG: delete called for transaction that is not open");
3465
3466        if (have_old && !old_sha1)
3467                die("BUG: have_old is true but old_sha1 is NULL");
3468
3469        update = add_update(transaction, refname);
3470        update->flags = flags;
3471        update->have_old = have_old;
3472        if (have_old) {
3473                assert(!is_null_sha1(old_sha1));
3474                hashcpy(update->old_sha1, old_sha1);
3475        }
3476        return 0;
3477}
3478
3479int update_ref(const char *action, const char *refname,
3480               const unsigned char *sha1, const unsigned char *oldval,
3481               int flags, enum action_on_err onerr)
3482{
3483        struct ref_transaction *t;
3484        struct strbuf err = STRBUF_INIT;
3485
3486        t = ref_transaction_begin(&err);
3487        if (!t ||
3488            ref_transaction_update(t, refname, sha1, oldval, flags,
3489                                   !!oldval, &err) ||
3490            ref_transaction_commit(t, action, &err)) {
3491                const char *str = "update_ref failed for ref '%s': %s";
3492
3493                ref_transaction_free(t);
3494                switch (onerr) {
3495                case UPDATE_REFS_MSG_ON_ERR:
3496                        error(str, refname, err.buf);
3497                        break;
3498                case UPDATE_REFS_DIE_ON_ERR:
3499                        die(str, refname, err.buf);
3500                        break;
3501                case UPDATE_REFS_QUIET_ON_ERR:
3502                        break;
3503                }
3504                strbuf_release(&err);
3505                return 1;
3506        }
3507        strbuf_release(&err);
3508        ref_transaction_free(t);
3509        return 0;
3510}
3511
3512static int ref_update_compare(const void *r1, const void *r2)
3513{
3514        const struct ref_update * const *u1 = r1;
3515        const struct ref_update * const *u2 = r2;
3516        return strcmp((*u1)->refname, (*u2)->refname);
3517}
3518
3519static int ref_update_reject_duplicates(struct ref_update **updates, int n,
3520                                        struct strbuf *err)
3521{
3522        int i;
3523        for (i = 1; i < n; i++)
3524                if (!strcmp(updates[i - 1]->refname, updates[i]->refname)) {
3525                        const char *str =
3526                                "Multiple updates for ref '%s' not allowed.";
3527                        if (err)
3528                                strbuf_addf(err, str, updates[i]->refname);
3529
3530                        return 1;
3531                }
3532        return 0;
3533}
3534
3535int ref_transaction_commit(struct ref_transaction *transaction,
3536                           const char *msg, struct strbuf *err)
3537{
3538        int ret = 0, delnum = 0, i;
3539        const char **delnames;
3540        int n = transaction->nr;
3541        struct ref_update **updates = transaction->updates;
3542
3543        if (transaction->state != REF_TRANSACTION_OPEN)
3544                die("BUG: commit called for transaction that is not open");
3545
3546        if (!n) {
3547                transaction->state = REF_TRANSACTION_CLOSED;
3548                return 0;
3549        }
3550
3551        /* Allocate work space */
3552        delnames = xmalloc(sizeof(*delnames) * n);
3553
3554        /* Copy, sort, and reject duplicate refs */
3555        qsort(updates, n, sizeof(*updates), ref_update_compare);
3556        ret = ref_update_reject_duplicates(updates, n, err);
3557        if (ret)
3558                goto cleanup;
3559
3560        /* Acquire all locks while verifying old values */
3561        for (i = 0; i < n; i++) {
3562                struct ref_update *update = updates[i];
3563
3564                update->lock = lock_any_ref_for_update(update->refname,
3565                                                       (update->have_old ?
3566                                                        update->old_sha1 :
3567                                                        NULL),
3568                                                       update->flags,
3569                                                       &update->type);
3570                if (!update->lock) {
3571                        if (err)
3572                                strbuf_addf(err, "Cannot lock the ref '%s'.",
3573                                            update->refname);
3574                        ret = 1;
3575                        goto cleanup;
3576                }
3577        }
3578
3579        /* Perform updates first so live commits remain referenced */
3580        for (i = 0; i < n; i++) {
3581                struct ref_update *update = updates[i];
3582
3583                if (!is_null_sha1(update->new_sha1)) {
3584                        ret = write_ref_sha1(update->lock, update->new_sha1,
3585                                             msg);
3586                        update->lock = NULL; /* freed by write_ref_sha1 */
3587                        if (ret) {
3588                                if (err)
3589                                        strbuf_addf(err, "Cannot update the ref '%s'.",
3590                                                    update->refname);
3591                                goto cleanup;
3592                        }
3593                }
3594        }
3595
3596        /* Perform deletes now that updates are safely completed */
3597        for (i = 0; i < n; i++) {
3598                struct ref_update *update = updates[i];
3599
3600                if (update->lock) {
3601                        delnames[delnum++] = update->lock->ref_name;
3602                        ret |= delete_ref_loose(update->lock, update->type);
3603                }
3604        }
3605
3606        ret |= repack_without_refs(delnames, delnum, err);
3607        for (i = 0; i < delnum; i++)
3608                unlink_or_warn(git_path("logs/%s", delnames[i]));
3609        clear_loose_ref_cache(&ref_cache);
3610
3611cleanup:
3612        transaction->state = REF_TRANSACTION_CLOSED;
3613
3614        for (i = 0; i < n; i++)
3615                if (updates[i]->lock)
3616                        unlock_ref(updates[i]->lock);
3617        free(delnames);
3618        return ret;
3619}
3620
3621char *shorten_unambiguous_ref(const char *refname, int strict)
3622{
3623        int i;
3624        static char **scanf_fmts;
3625        static int nr_rules;
3626        char *short_name;
3627
3628        if (!nr_rules) {
3629                /*
3630                 * Pre-generate scanf formats from ref_rev_parse_rules[].
3631                 * Generate a format suitable for scanf from a
3632                 * ref_rev_parse_rules rule by interpolating "%s" at the
3633                 * location of the "%.*s".
3634                 */
3635                size_t total_len = 0;
3636                size_t offset = 0;
3637
3638                /* the rule list is NULL terminated, count them first */
3639                for (nr_rules = 0; ref_rev_parse_rules[nr_rules]; nr_rules++)
3640                        /* -2 for strlen("%.*s") - strlen("%s"); +1 for NUL */
3641                        total_len += strlen(ref_rev_parse_rules[nr_rules]) - 2 + 1;
3642
3643                scanf_fmts = xmalloc(nr_rules * sizeof(char *) + total_len);
3644
3645                offset = 0;
3646                for (i = 0; i < nr_rules; i++) {
3647                        assert(offset < total_len);
3648                        scanf_fmts[i] = (char *)&scanf_fmts[nr_rules] + offset;
3649                        offset += snprintf(scanf_fmts[i], total_len - offset,
3650                                           ref_rev_parse_rules[i], 2, "%s") + 1;
3651                }
3652        }
3653
3654        /* bail out if there are no rules */
3655        if (!nr_rules)
3656                return xstrdup(refname);
3657
3658        /* buffer for scanf result, at most refname must fit */
3659        short_name = xstrdup(refname);
3660
3661        /* skip first rule, it will always match */
3662        for (i = nr_rules - 1; i > 0 ; --i) {
3663                int j;
3664                int rules_to_fail = i;
3665                int short_name_len;
3666
3667                if (1 != sscanf(refname, scanf_fmts[i], short_name))
3668                        continue;
3669
3670                short_name_len = strlen(short_name);
3671
3672                /*
3673                 * in strict mode, all (except the matched one) rules
3674                 * must fail to resolve to a valid non-ambiguous ref
3675                 */
3676                if (strict)
3677                        rules_to_fail = nr_rules;
3678
3679                /*
3680                 * check if the short name resolves to a valid ref,
3681                 * but use only rules prior to the matched one
3682                 */
3683                for (j = 0; j < rules_to_fail; j++) {
3684                        const char *rule = ref_rev_parse_rules[j];
3685                        char refname[PATH_MAX];
3686
3687                        /* skip matched rule */
3688                        if (i == j)
3689                                continue;
3690
3691                        /*
3692                         * the short name is ambiguous, if it resolves
3693                         * (with this previous rule) to a valid ref
3694                         * read_ref() returns 0 on success
3695                         */
3696                        mksnpath(refname, sizeof(refname),
3697                                 rule, short_name_len, short_name);
3698                        if (ref_exists(refname))
3699                                break;
3700                }
3701
3702                /*
3703                 * short name is non-ambiguous if all previous rules
3704                 * haven't resolved to a valid ref
3705                 */
3706                if (j == rules_to_fail)
3707                        return short_name;
3708        }
3709
3710        free(short_name);
3711        return xstrdup(refname);
3712}
3713
3714static struct string_list *hide_refs;
3715
3716int parse_hide_refs_config(const char *var, const char *value, const char *section)
3717{
3718        if (!strcmp("transfer.hiderefs", var) ||
3719            /* NEEDSWORK: use parse_config_key() once both are merged */
3720            (starts_with(var, section) && var[strlen(section)] == '.' &&
3721             !strcmp(var + strlen(section), ".hiderefs"))) {
3722                char *ref;
3723                int len;
3724
3725                if (!value)
3726                        return config_error_nonbool(var);
3727                ref = xstrdup(value);
3728                len = strlen(ref);
3729                while (len && ref[len - 1] == '/')
3730                        ref[--len] = '\0';
3731                if (!hide_refs) {
3732                        hide_refs = xcalloc(1, sizeof(*hide_refs));
3733                        hide_refs->strdup_strings = 1;
3734                }
3735                string_list_append(hide_refs, ref);
3736        }
3737        return 0;
3738}
3739
3740int ref_is_hidden(const char *refname)
3741{
3742        struct string_list_item *item;
3743
3744        if (!hide_refs)
3745                return 0;
3746        for_each_string_list_item(item, hide_refs) {
3747                int len;
3748                if (!starts_with(refname, item->string))
3749                        continue;
3750                len = strlen(item->string);
3751                if (!refname[len] || refname[len] == '/')
3752                        return 1;
3753        }
3754        return 0;
3755}