refs.con commit refs: change how packed refs are deleted (506a760)
   1#include "cache.h"
   2#include "refs.h"
   3#include "object.h"
   4#include "tag.h"
   5#include "dir.h"
   6
   7/*
   8 * Make sure "ref" is something reasonable to have under ".git/refs/";
   9 * We do not like it if:
  10 *
  11 * - any path component of it begins with ".", or
  12 * - it has double dots "..", or
  13 * - it has ASCII control character, "~", "^", ":" or SP, anywhere, or
  14 * - it ends with a "/".
  15 * - it ends with ".lock"
  16 * - it contains a "\" (backslash)
  17 */
  18
  19/* Return true iff ch is not allowed in reference names. */
  20static inline int bad_ref_char(int ch)
  21{
  22        if (((unsigned) ch) <= ' ' || ch == 0x7f ||
  23            ch == '~' || ch == '^' || ch == ':' || ch == '\\')
  24                return 1;
  25        /* 2.13 Pattern Matching Notation */
  26        if (ch == '*' || ch == '?' || ch == '[') /* Unsupported */
  27                return 1;
  28        return 0;
  29}
  30
  31/*
  32 * Try to read one refname component from the front of refname.  Return
  33 * the length of the component found, or -1 if the component is not
  34 * legal.
  35 */
  36static int check_refname_component(const char *refname, int flags)
  37{
  38        const char *cp;
  39        char last = '\0';
  40
  41        for (cp = refname; ; cp++) {
  42                char ch = *cp;
  43                if (ch == '\0' || ch == '/')
  44                        break;
  45                if (bad_ref_char(ch))
  46                        return -1; /* Illegal character in refname. */
  47                if (last == '.' && ch == '.')
  48                        return -1; /* Refname contains "..". */
  49                if (last == '@' && ch == '{')
  50                        return -1; /* Refname contains "@{". */
  51                last = ch;
  52        }
  53        if (cp == refname)
  54                return 0; /* Component has zero length. */
  55        if (refname[0] == '.') {
  56                if (!(flags & REFNAME_DOT_COMPONENT))
  57                        return -1; /* Component starts with '.'. */
  58                /*
  59                 * Even if leading dots are allowed, don't allow "."
  60                 * as a component (".." is prevented by a rule above).
  61                 */
  62                if (refname[1] == '\0')
  63                        return -1; /* Component equals ".". */
  64        }
  65        if (cp - refname >= 5 && !memcmp(cp - 5, ".lock", 5))
  66                return -1; /* Refname ends with ".lock". */
  67        return cp - refname;
  68}
  69
  70int check_refname_format(const char *refname, int flags)
  71{
  72        int component_len, component_count = 0;
  73
  74        while (1) {
  75                /* We are at the start of a path component. */
  76                component_len = check_refname_component(refname, flags);
  77                if (component_len <= 0) {
  78                        if ((flags & REFNAME_REFSPEC_PATTERN) &&
  79                                        refname[0] == '*' &&
  80                                        (refname[1] == '\0' || refname[1] == '/')) {
  81                                /* Accept one wildcard as a full refname component. */
  82                                flags &= ~REFNAME_REFSPEC_PATTERN;
  83                                component_len = 1;
  84                        } else {
  85                                return -1;
  86                        }
  87                }
  88                component_count++;
  89                if (refname[component_len] == '\0')
  90                        break;
  91                /* Skip to next component. */
  92                refname += component_len + 1;
  93        }
  94
  95        if (refname[component_len - 1] == '.')
  96                return -1; /* Refname ends with '.'. */
  97        if (!(flags & REFNAME_ALLOW_ONELEVEL) && component_count < 2)
  98                return -1; /* Refname has only one component. */
  99        return 0;
 100}
 101
 102struct ref_entry;
 103
 104/*
 105 * Information used (along with the information in ref_entry) to
 106 * describe a single cached reference.  This data structure only
 107 * occurs embedded in a union in struct ref_entry, and only when
 108 * (ref_entry->flag & REF_DIR) is zero.
 109 */
 110struct ref_value {
 111        /*
 112         * The name of the object to which this reference resolves
 113         * (which may be a tag object).  If REF_ISBROKEN, this is
 114         * null.  If REF_ISSYMREF, then this is the name of the object
 115         * referred to by the last reference in the symlink chain.
 116         */
 117        unsigned char sha1[20];
 118
 119        /*
 120         * If REF_KNOWS_PEELED, then this field holds the peeled value
 121         * of this reference, or null if the reference is known not to
 122         * be peelable.  See the documentation for peel_ref() for an
 123         * exact definition of "peelable".
 124         */
 125        unsigned char peeled[20];
 126};
 127
 128struct ref_cache;
 129
 130/*
 131 * Information used (along with the information in ref_entry) to
 132 * describe a level in the hierarchy of references.  This data
 133 * structure only occurs embedded in a union in struct ref_entry, and
 134 * only when (ref_entry.flag & REF_DIR) is set.  In that case,
 135 * (ref_entry.flag & REF_INCOMPLETE) determines whether the references
 136 * in the directory have already been read:
 137 *
 138 *     (ref_entry.flag & REF_INCOMPLETE) unset -- a directory of loose
 139 *         or packed references, already read.
 140 *
 141 *     (ref_entry.flag & REF_INCOMPLETE) set -- a directory of loose
 142 *         references that hasn't been read yet (nor has any of its
 143 *         subdirectories).
 144 *
 145 * Entries within a directory are stored within a growable array of
 146 * pointers to ref_entries (entries, nr, alloc).  Entries 0 <= i <
 147 * sorted are sorted by their component name in strcmp() order and the
 148 * remaining entries are unsorted.
 149 *
 150 * Loose references are read lazily, one directory at a time.  When a
 151 * directory of loose references is read, then all of the references
 152 * in that directory are stored, and REF_INCOMPLETE stubs are created
 153 * for any subdirectories, but the subdirectories themselves are not
 154 * read.  The reading is triggered by get_ref_dir().
 155 */
 156struct ref_dir {
 157        int nr, alloc;
 158
 159        /*
 160         * Entries with index 0 <= i < sorted are sorted by name.  New
 161         * entries are appended to the list unsorted, and are sorted
 162         * only when required; thus we avoid the need to sort the list
 163         * after the addition of every reference.
 164         */
 165        int sorted;
 166
 167        /* A pointer to the ref_cache that contains this ref_dir. */
 168        struct ref_cache *ref_cache;
 169
 170        struct ref_entry **entries;
 171};
 172
 173/*
 174 * Bit values for ref_entry::flag.  REF_ISSYMREF=0x01,
 175 * REF_ISPACKED=0x02, and REF_ISBROKEN=0x04 are public values; see
 176 * refs.h.
 177 */
 178
 179/*
 180 * The field ref_entry->u.value.peeled of this value entry contains
 181 * the correct peeled value for the reference, which might be
 182 * null_sha1 if the reference is not a tag or if it is broken.
 183 */
 184#define REF_KNOWS_PEELED 0x08
 185
 186/* ref_entry represents a directory of references */
 187#define REF_DIR 0x10
 188
 189/*
 190 * Entry has not yet been read from disk (used only for REF_DIR
 191 * entries representing loose references)
 192 */
 193#define REF_INCOMPLETE 0x20
 194
 195/*
 196 * A ref_entry represents either a reference or a "subdirectory" of
 197 * references.
 198 *
 199 * Each directory in the reference namespace is represented by a
 200 * ref_entry with (flags & REF_DIR) set and containing a subdir member
 201 * that holds the entries in that directory that have been read so
 202 * far.  If (flags & REF_INCOMPLETE) is set, then the directory and
 203 * its subdirectories haven't been read yet.  REF_INCOMPLETE is only
 204 * used for loose reference directories.
 205 *
 206 * References are represented by a ref_entry with (flags & REF_DIR)
 207 * unset and a value member that describes the reference's value.  The
 208 * flag member is at the ref_entry level, but it is also needed to
 209 * interpret the contents of the value field (in other words, a
 210 * ref_value object is not very much use without the enclosing
 211 * ref_entry).
 212 *
 213 * Reference names cannot end with slash and directories' names are
 214 * always stored with a trailing slash (except for the top-level
 215 * directory, which is always denoted by "").  This has two nice
 216 * consequences: (1) when the entries in each subdir are sorted
 217 * lexicographically by name (as they usually are), the references in
 218 * a whole tree can be generated in lexicographic order by traversing
 219 * the tree in left-to-right, depth-first order; (2) the names of
 220 * references and subdirectories cannot conflict, and therefore the
 221 * presence of an empty subdirectory does not block the creation of a
 222 * similarly-named reference.  (The fact that reference names with the
 223 * same leading components can conflict *with each other* is a
 224 * separate issue that is regulated by is_refname_available().)
 225 *
 226 * Please note that the name field contains the fully-qualified
 227 * reference (or subdirectory) name.  Space could be saved by only
 228 * storing the relative names.  But that would require the full names
 229 * to be generated on the fly when iterating in do_for_each_ref(), and
 230 * would break callback functions, who have always been able to assume
 231 * that the name strings that they are passed will not be freed during
 232 * the iteration.
 233 */
 234struct ref_entry {
 235        unsigned char flag; /* ISSYMREF? ISPACKED? */
 236        union {
 237                struct ref_value value; /* if not (flags&REF_DIR) */
 238                struct ref_dir subdir; /* if (flags&REF_DIR) */
 239        } u;
 240        /*
 241         * The full name of the reference (e.g., "refs/heads/master")
 242         * or the full name of the directory with a trailing slash
 243         * (e.g., "refs/heads/"):
 244         */
 245        char name[FLEX_ARRAY];
 246};
 247
 248static void read_loose_refs(const char *dirname, struct ref_dir *dir);
 249
 250static struct ref_dir *get_ref_dir(struct ref_entry *entry)
 251{
 252        struct ref_dir *dir;
 253        assert(entry->flag & REF_DIR);
 254        dir = &entry->u.subdir;
 255        if (entry->flag & REF_INCOMPLETE) {
 256                read_loose_refs(entry->name, dir);
 257                entry->flag &= ~REF_INCOMPLETE;
 258        }
 259        return dir;
 260}
 261
 262static struct ref_entry *create_ref_entry(const char *refname,
 263                                          const unsigned char *sha1, int flag,
 264                                          int check_name)
 265{
 266        int len;
 267        struct ref_entry *ref;
 268
 269        if (check_name &&
 270            check_refname_format(refname, REFNAME_ALLOW_ONELEVEL|REFNAME_DOT_COMPONENT))
 271                die("Reference has invalid format: '%s'", refname);
 272        len = strlen(refname) + 1;
 273        ref = xmalloc(sizeof(struct ref_entry) + len);
 274        hashcpy(ref->u.value.sha1, sha1);
 275        hashclr(ref->u.value.peeled);
 276        memcpy(ref->name, refname, len);
 277        ref->flag = flag;
 278        return ref;
 279}
 280
 281static void clear_ref_dir(struct ref_dir *dir);
 282
 283static void free_ref_entry(struct ref_entry *entry)
 284{
 285        if (entry->flag & REF_DIR) {
 286                /*
 287                 * Do not use get_ref_dir() here, as that might
 288                 * trigger the reading of loose refs.
 289                 */
 290                clear_ref_dir(&entry->u.subdir);
 291        }
 292        free(entry);
 293}
 294
 295/*
 296 * Add a ref_entry to the end of dir (unsorted).  Entry is always
 297 * stored directly in dir; no recursion into subdirectories is
 298 * done.
 299 */
 300static void add_entry_to_dir(struct ref_dir *dir, struct ref_entry *entry)
 301{
 302        ALLOC_GROW(dir->entries, dir->nr + 1, dir->alloc);
 303        dir->entries[dir->nr++] = entry;
 304        /* optimize for the case that entries are added in order */
 305        if (dir->nr == 1 ||
 306            (dir->nr == dir->sorted + 1 &&
 307             strcmp(dir->entries[dir->nr - 2]->name,
 308                    dir->entries[dir->nr - 1]->name) < 0))
 309                dir->sorted = dir->nr;
 310}
 311
 312/*
 313 * Clear and free all entries in dir, recursively.
 314 */
 315static void clear_ref_dir(struct ref_dir *dir)
 316{
 317        int i;
 318        for (i = 0; i < dir->nr; i++)
 319                free_ref_entry(dir->entries[i]);
 320        free(dir->entries);
 321        dir->sorted = dir->nr = dir->alloc = 0;
 322        dir->entries = NULL;
 323}
 324
 325/*
 326 * Create a struct ref_entry object for the specified dirname.
 327 * dirname is the name of the directory with a trailing slash (e.g.,
 328 * "refs/heads/") or "" for the top-level directory.
 329 */
 330static struct ref_entry *create_dir_entry(struct ref_cache *ref_cache,
 331                                          const char *dirname, size_t len,
 332                                          int incomplete)
 333{
 334        struct ref_entry *direntry;
 335        direntry = xcalloc(1, sizeof(struct ref_entry) + len + 1);
 336        memcpy(direntry->name, dirname, len);
 337        direntry->name[len] = '\0';
 338        direntry->u.subdir.ref_cache = ref_cache;
 339        direntry->flag = REF_DIR | (incomplete ? REF_INCOMPLETE : 0);
 340        return direntry;
 341}
 342
 343static int ref_entry_cmp(const void *a, const void *b)
 344{
 345        struct ref_entry *one = *(struct ref_entry **)a;
 346        struct ref_entry *two = *(struct ref_entry **)b;
 347        return strcmp(one->name, two->name);
 348}
 349
 350static void sort_ref_dir(struct ref_dir *dir);
 351
 352struct string_slice {
 353        size_t len;
 354        const char *str;
 355};
 356
 357static int ref_entry_cmp_sslice(const void *key_, const void *ent_)
 358{
 359        struct string_slice *key = (struct string_slice *)key_;
 360        struct ref_entry *ent = *(struct ref_entry **)ent_;
 361        int entlen = strlen(ent->name);
 362        int cmplen = key->len < entlen ? key->len : entlen;
 363        int cmp = memcmp(key->str, ent->name, cmplen);
 364        if (cmp)
 365                return cmp;
 366        return key->len - entlen;
 367}
 368
 369/*
 370 * Return the index of the entry with the given refname from the
 371 * ref_dir (non-recursively), sorting dir if necessary.  Return -1 if
 372 * no such entry is found.  dir must already be complete.
 373 */
 374static int search_ref_dir(struct ref_dir *dir, const char *refname, size_t len)
 375{
 376        struct ref_entry **r;
 377        struct string_slice key;
 378
 379        if (refname == NULL || !dir->nr)
 380                return -1;
 381
 382        sort_ref_dir(dir);
 383        key.len = len;
 384        key.str = refname;
 385        r = bsearch(&key, dir->entries, dir->nr, sizeof(*dir->entries),
 386                    ref_entry_cmp_sslice);
 387
 388        if (r == NULL)
 389                return -1;
 390
 391        return r - dir->entries;
 392}
 393
 394/*
 395 * Search for a directory entry directly within dir (without
 396 * recursing).  Sort dir if necessary.  subdirname must be a directory
 397 * name (i.e., end in '/').  If mkdir is set, then create the
 398 * directory if it is missing; otherwise, return NULL if the desired
 399 * directory cannot be found.  dir must already be complete.
 400 */
 401static struct ref_dir *search_for_subdir(struct ref_dir *dir,
 402                                         const char *subdirname, size_t len,
 403                                         int mkdir)
 404{
 405        int entry_index = search_ref_dir(dir, subdirname, len);
 406        struct ref_entry *entry;
 407        if (entry_index == -1) {
 408                if (!mkdir)
 409                        return NULL;
 410                /*
 411                 * Since dir is complete, the absence of a subdir
 412                 * means that the subdir really doesn't exist;
 413                 * therefore, create an empty record for it but mark
 414                 * the record complete.
 415                 */
 416                entry = create_dir_entry(dir->ref_cache, subdirname, len, 0);
 417                add_entry_to_dir(dir, entry);
 418        } else {
 419                entry = dir->entries[entry_index];
 420        }
 421        return get_ref_dir(entry);
 422}
 423
 424/*
 425 * If refname is a reference name, find the ref_dir within the dir
 426 * tree that should hold refname.  If refname is a directory name
 427 * (i.e., ends in '/'), then return that ref_dir itself.  dir must
 428 * represent the top-level directory and must already be complete.
 429 * Sort ref_dirs and recurse into subdirectories as necessary.  If
 430 * mkdir is set, then create any missing directories; otherwise,
 431 * return NULL if the desired directory cannot be found.
 432 */
 433static struct ref_dir *find_containing_dir(struct ref_dir *dir,
 434                                           const char *refname, int mkdir)
 435{
 436        const char *slash;
 437        for (slash = strchr(refname, '/'); slash; slash = strchr(slash + 1, '/')) {
 438                size_t dirnamelen = slash - refname + 1;
 439                struct ref_dir *subdir;
 440                subdir = search_for_subdir(dir, refname, dirnamelen, mkdir);
 441                if (!subdir) {
 442                        dir = NULL;
 443                        break;
 444                }
 445                dir = subdir;
 446        }
 447
 448        return dir;
 449}
 450
 451/*
 452 * Find the value entry with the given name in dir, sorting ref_dirs
 453 * and recursing into subdirectories as necessary.  If the name is not
 454 * found or it corresponds to a directory entry, return NULL.
 455 */
 456static struct ref_entry *find_ref(struct ref_dir *dir, const char *refname)
 457{
 458        int entry_index;
 459        struct ref_entry *entry;
 460        dir = find_containing_dir(dir, refname, 0);
 461        if (!dir)
 462                return NULL;
 463        entry_index = search_ref_dir(dir, refname, strlen(refname));
 464        if (entry_index == -1)
 465                return NULL;
 466        entry = dir->entries[entry_index];
 467        return (entry->flag & REF_DIR) ? NULL : entry;
 468}
 469
 470/*
 471 * Remove the entry with the given name from dir, recursing into
 472 * subdirectories as necessary.  If refname is the name of a directory
 473 * (i.e., ends with '/'), then remove the directory and its contents.
 474 * If the removal was successful, return the number of entries
 475 * remaining in the directory entry that contained the deleted entry.
 476 * If the name was not found, return -1.  Please note that this
 477 * function only deletes the entry from the cache; it does not delete
 478 * it from the filesystem or ensure that other cache entries (which
 479 * might be symbolic references to the removed entry) are updated.
 480 * Nor does it remove any containing dir entries that might be made
 481 * empty by the removal.  dir must represent the top-level directory
 482 * and must already be complete.
 483 */
 484static int remove_entry(struct ref_dir *dir, const char *refname)
 485{
 486        int refname_len = strlen(refname);
 487        int entry_index;
 488        struct ref_entry *entry;
 489        int is_dir = refname[refname_len - 1] == '/';
 490        if (is_dir) {
 491                /*
 492                 * refname represents a reference directory.  Remove
 493                 * the trailing slash; otherwise we will get the
 494                 * directory *representing* refname rather than the
 495                 * one *containing* it.
 496                 */
 497                char *dirname = xmemdupz(refname, refname_len - 1);
 498                dir = find_containing_dir(dir, dirname, 0);
 499                free(dirname);
 500        } else {
 501                dir = find_containing_dir(dir, refname, 0);
 502        }
 503        if (!dir)
 504                return -1;
 505        entry_index = search_ref_dir(dir, refname, refname_len);
 506        if (entry_index == -1)
 507                return -1;
 508        entry = dir->entries[entry_index];
 509
 510        memmove(&dir->entries[entry_index],
 511                &dir->entries[entry_index + 1],
 512                (dir->nr - entry_index - 1) * sizeof(*dir->entries)
 513                );
 514        dir->nr--;
 515        if (dir->sorted > entry_index)
 516                dir->sorted--;
 517        free_ref_entry(entry);
 518        return dir->nr;
 519}
 520
 521/*
 522 * Add a ref_entry to the ref_dir (unsorted), recursing into
 523 * subdirectories as necessary.  dir must represent the top-level
 524 * directory.  Return 0 on success.
 525 */
 526static int add_ref(struct ref_dir *dir, struct ref_entry *ref)
 527{
 528        dir = find_containing_dir(dir, ref->name, 1);
 529        if (!dir)
 530                return -1;
 531        add_entry_to_dir(dir, ref);
 532        return 0;
 533}
 534
 535/*
 536 * Emit a warning and return true iff ref1 and ref2 have the same name
 537 * and the same sha1.  Die if they have the same name but different
 538 * sha1s.
 539 */
 540static int is_dup_ref(const struct ref_entry *ref1, const struct ref_entry *ref2)
 541{
 542        if (strcmp(ref1->name, ref2->name))
 543                return 0;
 544
 545        /* Duplicate name; make sure that they don't conflict: */
 546
 547        if ((ref1->flag & REF_DIR) || (ref2->flag & REF_DIR))
 548                /* This is impossible by construction */
 549                die("Reference directory conflict: %s", ref1->name);
 550
 551        if (hashcmp(ref1->u.value.sha1, ref2->u.value.sha1))
 552                die("Duplicated ref, and SHA1s don't match: %s", ref1->name);
 553
 554        warning("Duplicated ref: %s", ref1->name);
 555        return 1;
 556}
 557
 558/*
 559 * Sort the entries in dir non-recursively (if they are not already
 560 * sorted) and remove any duplicate entries.
 561 */
 562static void sort_ref_dir(struct ref_dir *dir)
 563{
 564        int i, j;
 565        struct ref_entry *last = NULL;
 566
 567        /*
 568         * This check also prevents passing a zero-length array to qsort(),
 569         * which is a problem on some platforms.
 570         */
 571        if (dir->sorted == dir->nr)
 572                return;
 573
 574        qsort(dir->entries, dir->nr, sizeof(*dir->entries), ref_entry_cmp);
 575
 576        /* Remove any duplicates: */
 577        for (i = 0, j = 0; j < dir->nr; j++) {
 578                struct ref_entry *entry = dir->entries[j];
 579                if (last && is_dup_ref(last, entry))
 580                        free_ref_entry(entry);
 581                else
 582                        last = dir->entries[i++] = entry;
 583        }
 584        dir->sorted = dir->nr = i;
 585}
 586
 587/* Include broken references in a do_for_each_ref*() iteration: */
 588#define DO_FOR_EACH_INCLUDE_BROKEN 0x01
 589
 590/*
 591 * Return true iff the reference described by entry can be resolved to
 592 * an object in the database.  Emit a warning if the referred-to
 593 * object does not exist.
 594 */
 595static int ref_resolves_to_object(struct ref_entry *entry)
 596{
 597        if (entry->flag & REF_ISBROKEN)
 598                return 0;
 599        if (!has_sha1_file(entry->u.value.sha1)) {
 600                error("%s does not point to a valid object!", entry->name);
 601                return 0;
 602        }
 603        return 1;
 604}
 605
 606/*
 607 * current_ref is a performance hack: when iterating over references
 608 * using the for_each_ref*() functions, current_ref is set to the
 609 * current reference's entry before calling the callback function.  If
 610 * the callback function calls peel_ref(), then peel_ref() first
 611 * checks whether the reference to be peeled is the current reference
 612 * (it usually is) and if so, returns that reference's peeled version
 613 * if it is available.  This avoids a refname lookup in a common case.
 614 */
 615static struct ref_entry *current_ref;
 616
 617typedef int each_ref_entry_fn(struct ref_entry *entry, void *cb_data);
 618
 619struct ref_entry_cb {
 620        const char *base;
 621        int trim;
 622        int flags;
 623        each_ref_fn *fn;
 624        void *cb_data;
 625};
 626
 627/*
 628 * Handle one reference in a do_for_each_ref*()-style iteration,
 629 * calling an each_ref_fn for each entry.
 630 */
 631static int do_one_ref(struct ref_entry *entry, void *cb_data)
 632{
 633        struct ref_entry_cb *data = cb_data;
 634        int retval;
 635        if (prefixcmp(entry->name, data->base))
 636                return 0;
 637
 638        if (!(data->flags & DO_FOR_EACH_INCLUDE_BROKEN) &&
 639              !ref_resolves_to_object(entry))
 640                return 0;
 641
 642        current_ref = entry;
 643        retval = data->fn(entry->name + data->trim, entry->u.value.sha1,
 644                          entry->flag, data->cb_data);
 645        current_ref = NULL;
 646        return retval;
 647}
 648
 649/*
 650 * Call fn for each reference in dir that has index in the range
 651 * offset <= index < dir->nr.  Recurse into subdirectories that are in
 652 * that index range, sorting them before iterating.  This function
 653 * does not sort dir itself; it should be sorted beforehand.  fn is
 654 * called for all references, including broken ones.
 655 */
 656static int do_for_each_entry_in_dir(struct ref_dir *dir, int offset,
 657                                    each_ref_entry_fn fn, void *cb_data)
 658{
 659        int i;
 660        assert(dir->sorted == dir->nr);
 661        for (i = offset; i < dir->nr; i++) {
 662                struct ref_entry *entry = dir->entries[i];
 663                int retval;
 664                if (entry->flag & REF_DIR) {
 665                        struct ref_dir *subdir = get_ref_dir(entry);
 666                        sort_ref_dir(subdir);
 667                        retval = do_for_each_entry_in_dir(subdir, 0, fn, cb_data);
 668                } else {
 669                        retval = fn(entry, cb_data);
 670                }
 671                if (retval)
 672                        return retval;
 673        }
 674        return 0;
 675}
 676
 677/*
 678 * Call fn for each reference in the union of dir1 and dir2, in order
 679 * by refname.  Recurse into subdirectories.  If a value entry appears
 680 * in both dir1 and dir2, then only process the version that is in
 681 * dir2.  The input dirs must already be sorted, but subdirs will be
 682 * sorted as needed.  fn is called for all references, including
 683 * broken ones.
 684 */
 685static int do_for_each_entry_in_dirs(struct ref_dir *dir1,
 686                                     struct ref_dir *dir2,
 687                                     each_ref_entry_fn fn, void *cb_data)
 688{
 689        int retval;
 690        int i1 = 0, i2 = 0;
 691
 692        assert(dir1->sorted == dir1->nr);
 693        assert(dir2->sorted == dir2->nr);
 694        while (1) {
 695                struct ref_entry *e1, *e2;
 696                int cmp;
 697                if (i1 == dir1->nr) {
 698                        return do_for_each_entry_in_dir(dir2, i2, fn, cb_data);
 699                }
 700                if (i2 == dir2->nr) {
 701                        return do_for_each_entry_in_dir(dir1, i1, fn, cb_data);
 702                }
 703                e1 = dir1->entries[i1];
 704                e2 = dir2->entries[i2];
 705                cmp = strcmp(e1->name, e2->name);
 706                if (cmp == 0) {
 707                        if ((e1->flag & REF_DIR) && (e2->flag & REF_DIR)) {
 708                                /* Both are directories; descend them in parallel. */
 709                                struct ref_dir *subdir1 = get_ref_dir(e1);
 710                                struct ref_dir *subdir2 = get_ref_dir(e2);
 711                                sort_ref_dir(subdir1);
 712                                sort_ref_dir(subdir2);
 713                                retval = do_for_each_entry_in_dirs(
 714                                                subdir1, subdir2, fn, cb_data);
 715                                i1++;
 716                                i2++;
 717                        } else if (!(e1->flag & REF_DIR) && !(e2->flag & REF_DIR)) {
 718                                /* Both are references; ignore the one from dir1. */
 719                                retval = fn(e2, cb_data);
 720                                i1++;
 721                                i2++;
 722                        } else {
 723                                die("conflict between reference and directory: %s",
 724                                    e1->name);
 725                        }
 726                } else {
 727                        struct ref_entry *e;
 728                        if (cmp < 0) {
 729                                e = e1;
 730                                i1++;
 731                        } else {
 732                                e = e2;
 733                                i2++;
 734                        }
 735                        if (e->flag & REF_DIR) {
 736                                struct ref_dir *subdir = get_ref_dir(e);
 737                                sort_ref_dir(subdir);
 738                                retval = do_for_each_entry_in_dir(
 739                                                subdir, 0, fn, cb_data);
 740                        } else {
 741                                retval = fn(e, cb_data);
 742                        }
 743                }
 744                if (retval)
 745                        return retval;
 746        }
 747}
 748
 749/*
 750 * Return true iff refname1 and refname2 conflict with each other.
 751 * Two reference names conflict if one of them exactly matches the
 752 * leading components of the other; e.g., "foo/bar" conflicts with
 753 * both "foo" and with "foo/bar/baz" but not with "foo/bar" or
 754 * "foo/barbados".
 755 */
 756static int names_conflict(const char *refname1, const char *refname2)
 757{
 758        for (; *refname1 && *refname1 == *refname2; refname1++, refname2++)
 759                ;
 760        return (*refname1 == '\0' && *refname2 == '/')
 761                || (*refname1 == '/' && *refname2 == '\0');
 762}
 763
 764struct name_conflict_cb {
 765        const char *refname;
 766        const char *oldrefname;
 767        const char *conflicting_refname;
 768};
 769
 770static int name_conflict_fn(struct ref_entry *entry, void *cb_data)
 771{
 772        struct name_conflict_cb *data = (struct name_conflict_cb *)cb_data;
 773        if (data->oldrefname && !strcmp(data->oldrefname, entry->name))
 774                return 0;
 775        if (names_conflict(data->refname, entry->name)) {
 776                data->conflicting_refname = entry->name;
 777                return 1;
 778        }
 779        return 0;
 780}
 781
 782/*
 783 * Return true iff a reference named refname could be created without
 784 * conflicting with the name of an existing reference in dir.  If
 785 * oldrefname is non-NULL, ignore potential conflicts with oldrefname
 786 * (e.g., because oldrefname is scheduled for deletion in the same
 787 * operation).
 788 */
 789static int is_refname_available(const char *refname, const char *oldrefname,
 790                                struct ref_dir *dir)
 791{
 792        struct name_conflict_cb data;
 793        data.refname = refname;
 794        data.oldrefname = oldrefname;
 795        data.conflicting_refname = NULL;
 796
 797        sort_ref_dir(dir);
 798        if (do_for_each_entry_in_dir(dir, 0, name_conflict_fn, &data)) {
 799                error("'%s' exists; cannot create '%s'",
 800                      data.conflicting_refname, refname);
 801                return 0;
 802        }
 803        return 1;
 804}
 805
 806/*
 807 * Future: need to be in "struct repository"
 808 * when doing a full libification.
 809 */
 810static struct ref_cache {
 811        struct ref_cache *next;
 812        struct ref_entry *loose;
 813        struct ref_entry *packed;
 814        /* The submodule name, or "" for the main repo. */
 815        char name[FLEX_ARRAY];
 816} *ref_cache;
 817
 818static void clear_packed_ref_cache(struct ref_cache *refs)
 819{
 820        if (refs->packed) {
 821                free_ref_entry(refs->packed);
 822                refs->packed = NULL;
 823        }
 824}
 825
 826static void clear_loose_ref_cache(struct ref_cache *refs)
 827{
 828        if (refs->loose) {
 829                free_ref_entry(refs->loose);
 830                refs->loose = NULL;
 831        }
 832}
 833
 834static struct ref_cache *create_ref_cache(const char *submodule)
 835{
 836        int len;
 837        struct ref_cache *refs;
 838        if (!submodule)
 839                submodule = "";
 840        len = strlen(submodule) + 1;
 841        refs = xcalloc(1, sizeof(struct ref_cache) + len);
 842        memcpy(refs->name, submodule, len);
 843        return refs;
 844}
 845
 846/*
 847 * Return a pointer to a ref_cache for the specified submodule. For
 848 * the main repository, use submodule==NULL. The returned structure
 849 * will be allocated and initialized but not necessarily populated; it
 850 * should not be freed.
 851 */
 852static struct ref_cache *get_ref_cache(const char *submodule)
 853{
 854        struct ref_cache *refs = ref_cache;
 855        if (!submodule)
 856                submodule = "";
 857        while (refs) {
 858                if (!strcmp(submodule, refs->name))
 859                        return refs;
 860                refs = refs->next;
 861        }
 862
 863        refs = create_ref_cache(submodule);
 864        refs->next = ref_cache;
 865        ref_cache = refs;
 866        return refs;
 867}
 868
 869void invalidate_ref_cache(const char *submodule)
 870{
 871        struct ref_cache *refs = get_ref_cache(submodule);
 872        clear_packed_ref_cache(refs);
 873        clear_loose_ref_cache(refs);
 874}
 875
 876/* The length of a peeled reference line in packed-refs, including EOL: */
 877#define PEELED_LINE_LENGTH 42
 878
 879/*
 880 * Parse one line from a packed-refs file.  Write the SHA1 to sha1.
 881 * Return a pointer to the refname within the line (null-terminated),
 882 * or NULL if there was a problem.
 883 */
 884static const char *parse_ref_line(char *line, unsigned char *sha1)
 885{
 886        /*
 887         * 42: the answer to everything.
 888         *
 889         * In this case, it happens to be the answer to
 890         *  40 (length of sha1 hex representation)
 891         *  +1 (space in between hex and name)
 892         *  +1 (newline at the end of the line)
 893         */
 894        int len = strlen(line) - 42;
 895
 896        if (len <= 0)
 897                return NULL;
 898        if (get_sha1_hex(line, sha1) < 0)
 899                return NULL;
 900        if (!isspace(line[40]))
 901                return NULL;
 902        line += 41;
 903        if (isspace(*line))
 904                return NULL;
 905        if (line[len] != '\n')
 906                return NULL;
 907        line[len] = 0;
 908
 909        return line;
 910}
 911
 912/*
 913 * Read f, which is a packed-refs file, into dir.
 914 *
 915 * A comment line of the form "# pack-refs with: " may contain zero or
 916 * more traits. We interpret the traits as follows:
 917 *
 918 *   No traits:
 919 *
 920 *      Probably no references are peeled. But if the file contains a
 921 *      peeled value for a reference, we will use it.
 922 *
 923 *   peeled:
 924 *
 925 *      References under "refs/tags/", if they *can* be peeled, *are*
 926 *      peeled in this file. References outside of "refs/tags/" are
 927 *      probably not peeled even if they could have been, but if we find
 928 *      a peeled value for such a reference we will use it.
 929 *
 930 *   fully-peeled:
 931 *
 932 *      All references in the file that can be peeled are peeled.
 933 *      Inversely (and this is more important), any references in the
 934 *      file for which no peeled value is recorded is not peelable. This
 935 *      trait should typically be written alongside "peeled" for
 936 *      compatibility with older clients, but we do not require it
 937 *      (i.e., "peeled" is a no-op if "fully-peeled" is set).
 938 */
 939static void read_packed_refs(FILE *f, struct ref_dir *dir)
 940{
 941        struct ref_entry *last = NULL;
 942        char refline[PATH_MAX];
 943        enum { PEELED_NONE, PEELED_TAGS, PEELED_FULLY } peeled = PEELED_NONE;
 944
 945        while (fgets(refline, sizeof(refline), f)) {
 946                unsigned char sha1[20];
 947                const char *refname;
 948                static const char header[] = "# pack-refs with:";
 949
 950                if (!strncmp(refline, header, sizeof(header)-1)) {
 951                        const char *traits = refline + sizeof(header) - 1;
 952                        if (strstr(traits, " fully-peeled "))
 953                                peeled = PEELED_FULLY;
 954                        else if (strstr(traits, " peeled "))
 955                                peeled = PEELED_TAGS;
 956                        /* perhaps other traits later as well */
 957                        continue;
 958                }
 959
 960                refname = parse_ref_line(refline, sha1);
 961                if (refname) {
 962                        last = create_ref_entry(refname, sha1, REF_ISPACKED, 1);
 963                        if (peeled == PEELED_FULLY ||
 964                            (peeled == PEELED_TAGS && !prefixcmp(refname, "refs/tags/")))
 965                                last->flag |= REF_KNOWS_PEELED;
 966                        add_ref(dir, last);
 967                        continue;
 968                }
 969                if (last &&
 970                    refline[0] == '^' &&
 971                    strlen(refline) == PEELED_LINE_LENGTH &&
 972                    refline[PEELED_LINE_LENGTH - 1] == '\n' &&
 973                    !get_sha1_hex(refline + 1, sha1)) {
 974                        hashcpy(last->u.value.peeled, sha1);
 975                        /*
 976                         * Regardless of what the file header said,
 977                         * we definitely know the value of *this*
 978                         * reference:
 979                         */
 980                        last->flag |= REF_KNOWS_PEELED;
 981                }
 982        }
 983}
 984
 985static struct ref_dir *get_packed_refs(struct ref_cache *refs)
 986{
 987        if (!refs->packed) {
 988                const char *packed_refs_file;
 989                FILE *f;
 990
 991                refs->packed = create_dir_entry(refs, "", 0, 0);
 992                if (*refs->name)
 993                        packed_refs_file = git_path_submodule(refs->name, "packed-refs");
 994                else
 995                        packed_refs_file = git_path("packed-refs");
 996                f = fopen(packed_refs_file, "r");
 997                if (f) {
 998                        read_packed_refs(f, get_ref_dir(refs->packed));
 999                        fclose(f);
1000                }
1001        }
1002        return get_ref_dir(refs->packed);
1003}
1004
1005void add_packed_ref(const char *refname, const unsigned char *sha1)
1006{
1007        add_ref(get_packed_refs(get_ref_cache(NULL)),
1008                        create_ref_entry(refname, sha1, REF_ISPACKED, 1));
1009}
1010
1011/*
1012 * Read the loose references from the namespace dirname into dir
1013 * (without recursing).  dirname must end with '/'.  dir must be the
1014 * directory entry corresponding to dirname.
1015 */
1016static void read_loose_refs(const char *dirname, struct ref_dir *dir)
1017{
1018        struct ref_cache *refs = dir->ref_cache;
1019        DIR *d;
1020        const char *path;
1021        struct dirent *de;
1022        int dirnamelen = strlen(dirname);
1023        struct strbuf refname;
1024
1025        if (*refs->name)
1026                path = git_path_submodule(refs->name, "%s", dirname);
1027        else
1028                path = git_path("%s", dirname);
1029
1030        d = opendir(path);
1031        if (!d)
1032                return;
1033
1034        strbuf_init(&refname, dirnamelen + 257);
1035        strbuf_add(&refname, dirname, dirnamelen);
1036
1037        while ((de = readdir(d)) != NULL) {
1038                unsigned char sha1[20];
1039                struct stat st;
1040                int flag;
1041                const char *refdir;
1042
1043                if (de->d_name[0] == '.')
1044                        continue;
1045                if (has_extension(de->d_name, ".lock"))
1046                        continue;
1047                strbuf_addstr(&refname, de->d_name);
1048                refdir = *refs->name
1049                        ? git_path_submodule(refs->name, "%s", refname.buf)
1050                        : git_path("%s", refname.buf);
1051                if (stat(refdir, &st) < 0) {
1052                        ; /* silently ignore */
1053                } else if (S_ISDIR(st.st_mode)) {
1054                        strbuf_addch(&refname, '/');
1055                        add_entry_to_dir(dir,
1056                                         create_dir_entry(refs, refname.buf,
1057                                                          refname.len, 1));
1058                } else {
1059                        if (*refs->name) {
1060                                hashclr(sha1);
1061                                flag = 0;
1062                                if (resolve_gitlink_ref(refs->name, refname.buf, sha1) < 0) {
1063                                        hashclr(sha1);
1064                                        flag |= REF_ISBROKEN;
1065                                }
1066                        } else if (read_ref_full(refname.buf, sha1, 1, &flag)) {
1067                                hashclr(sha1);
1068                                flag |= REF_ISBROKEN;
1069                        }
1070                        add_entry_to_dir(dir,
1071                                         create_ref_entry(refname.buf, sha1, flag, 1));
1072                }
1073                strbuf_setlen(&refname, dirnamelen);
1074        }
1075        strbuf_release(&refname);
1076        closedir(d);
1077}
1078
1079static struct ref_dir *get_loose_refs(struct ref_cache *refs)
1080{
1081        if (!refs->loose) {
1082                /*
1083                 * Mark the top-level directory complete because we
1084                 * are about to read the only subdirectory that can
1085                 * hold references:
1086                 */
1087                refs->loose = create_dir_entry(refs, "", 0, 0);
1088                /*
1089                 * Create an incomplete entry for "refs/":
1090                 */
1091                add_entry_to_dir(get_ref_dir(refs->loose),
1092                                 create_dir_entry(refs, "refs/", 5, 1));
1093        }
1094        return get_ref_dir(refs->loose);
1095}
1096
1097/* We allow "recursive" symbolic refs. Only within reason, though */
1098#define MAXDEPTH 5
1099#define MAXREFLEN (1024)
1100
1101/*
1102 * Called by resolve_gitlink_ref_recursive() after it failed to read
1103 * from the loose refs in ref_cache refs. Find <refname> in the
1104 * packed-refs file for the submodule.
1105 */
1106static int resolve_gitlink_packed_ref(struct ref_cache *refs,
1107                                      const char *refname, unsigned char *sha1)
1108{
1109        struct ref_entry *ref;
1110        struct ref_dir *dir = get_packed_refs(refs);
1111
1112        ref = find_ref(dir, refname);
1113        if (ref == NULL)
1114                return -1;
1115
1116        memcpy(sha1, ref->u.value.sha1, 20);
1117        return 0;
1118}
1119
1120static int resolve_gitlink_ref_recursive(struct ref_cache *refs,
1121                                         const char *refname, unsigned char *sha1,
1122                                         int recursion)
1123{
1124        int fd, len;
1125        char buffer[128], *p;
1126        char *path;
1127
1128        if (recursion > MAXDEPTH || strlen(refname) > MAXREFLEN)
1129                return -1;
1130        path = *refs->name
1131                ? git_path_submodule(refs->name, "%s", refname)
1132                : git_path("%s", refname);
1133        fd = open(path, O_RDONLY);
1134        if (fd < 0)
1135                return resolve_gitlink_packed_ref(refs, refname, sha1);
1136
1137        len = read(fd, buffer, sizeof(buffer)-1);
1138        close(fd);
1139        if (len < 0)
1140                return -1;
1141        while (len && isspace(buffer[len-1]))
1142                len--;
1143        buffer[len] = 0;
1144
1145        /* Was it a detached head or an old-fashioned symlink? */
1146        if (!get_sha1_hex(buffer, sha1))
1147                return 0;
1148
1149        /* Symref? */
1150        if (strncmp(buffer, "ref:", 4))
1151                return -1;
1152        p = buffer + 4;
1153        while (isspace(*p))
1154                p++;
1155
1156        return resolve_gitlink_ref_recursive(refs, p, sha1, recursion+1);
1157}
1158
1159int resolve_gitlink_ref(const char *path, const char *refname, unsigned char *sha1)
1160{
1161        int len = strlen(path), retval;
1162        char *submodule;
1163        struct ref_cache *refs;
1164
1165        while (len && path[len-1] == '/')
1166                len--;
1167        if (!len)
1168                return -1;
1169        submodule = xstrndup(path, len);
1170        refs = get_ref_cache(submodule);
1171        free(submodule);
1172
1173        retval = resolve_gitlink_ref_recursive(refs, refname, sha1, 0);
1174        return retval;
1175}
1176
1177/*
1178 * Return the ref_entry for the given refname from the packed
1179 * references.  If it does not exist, return NULL.
1180 */
1181static struct ref_entry *get_packed_ref(const char *refname)
1182{
1183        return find_ref(get_packed_refs(get_ref_cache(NULL)), refname);
1184}
1185
1186const char *resolve_ref_unsafe(const char *refname, unsigned char *sha1, int reading, int *flag)
1187{
1188        int depth = MAXDEPTH;
1189        ssize_t len;
1190        char buffer[256];
1191        static char refname_buffer[256];
1192
1193        if (flag)
1194                *flag = 0;
1195
1196        if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL))
1197                return NULL;
1198
1199        for (;;) {
1200                char path[PATH_MAX];
1201                struct stat st;
1202                char *buf;
1203                int fd;
1204
1205                if (--depth < 0)
1206                        return NULL;
1207
1208                git_snpath(path, sizeof(path), "%s", refname);
1209
1210                if (lstat(path, &st) < 0) {
1211                        struct ref_entry *entry;
1212
1213                        if (errno != ENOENT)
1214                                return NULL;
1215                        /*
1216                         * The loose reference file does not exist;
1217                         * check for a packed reference.
1218                         */
1219                        entry = get_packed_ref(refname);
1220                        if (entry) {
1221                                hashcpy(sha1, entry->u.value.sha1);
1222                                if (flag)
1223                                        *flag |= REF_ISPACKED;
1224                                return refname;
1225                        }
1226                        /* The reference is not a packed reference, either. */
1227                        if (reading) {
1228                                return NULL;
1229                        } else {
1230                                hashclr(sha1);
1231                                return refname;
1232                        }
1233                }
1234
1235                /* Follow "normalized" - ie "refs/.." symlinks by hand */
1236                if (S_ISLNK(st.st_mode)) {
1237                        len = readlink(path, buffer, sizeof(buffer)-1);
1238                        if (len < 0)
1239                                return NULL;
1240                        buffer[len] = 0;
1241                        if (!prefixcmp(buffer, "refs/") &&
1242                                        !check_refname_format(buffer, 0)) {
1243                                strcpy(refname_buffer, buffer);
1244                                refname = refname_buffer;
1245                                if (flag)
1246                                        *flag |= REF_ISSYMREF;
1247                                continue;
1248                        }
1249                }
1250
1251                /* Is it a directory? */
1252                if (S_ISDIR(st.st_mode)) {
1253                        errno = EISDIR;
1254                        return NULL;
1255                }
1256
1257                /*
1258                 * Anything else, just open it and try to use it as
1259                 * a ref
1260                 */
1261                fd = open(path, O_RDONLY);
1262                if (fd < 0)
1263                        return NULL;
1264                len = read_in_full(fd, buffer, sizeof(buffer)-1);
1265                close(fd);
1266                if (len < 0)
1267                        return NULL;
1268                while (len && isspace(buffer[len-1]))
1269                        len--;
1270                buffer[len] = '\0';
1271
1272                /*
1273                 * Is it a symbolic ref?
1274                 */
1275                if (prefixcmp(buffer, "ref:"))
1276                        break;
1277                if (flag)
1278                        *flag |= REF_ISSYMREF;
1279                buf = buffer + 4;
1280                while (isspace(*buf))
1281                        buf++;
1282                if (check_refname_format(buf, REFNAME_ALLOW_ONELEVEL)) {
1283                        if (flag)
1284                                *flag |= REF_ISBROKEN;
1285                        return NULL;
1286                }
1287                refname = strcpy(refname_buffer, buf);
1288        }
1289        /* Please note that FETCH_HEAD has a second line containing other data. */
1290        if (get_sha1_hex(buffer, sha1) || (buffer[40] != '\0' && !isspace(buffer[40]))) {
1291                if (flag)
1292                        *flag |= REF_ISBROKEN;
1293                return NULL;
1294        }
1295        return refname;
1296}
1297
1298char *resolve_refdup(const char *ref, unsigned char *sha1, int reading, int *flag)
1299{
1300        const char *ret = resolve_ref_unsafe(ref, sha1, reading, flag);
1301        return ret ? xstrdup(ret) : NULL;
1302}
1303
1304/* The argument to filter_refs */
1305struct ref_filter {
1306        const char *pattern;
1307        each_ref_fn *fn;
1308        void *cb_data;
1309};
1310
1311int read_ref_full(const char *refname, unsigned char *sha1, int reading, int *flags)
1312{
1313        if (resolve_ref_unsafe(refname, sha1, reading, flags))
1314                return 0;
1315        return -1;
1316}
1317
1318int read_ref(const char *refname, unsigned char *sha1)
1319{
1320        return read_ref_full(refname, sha1, 1, NULL);
1321}
1322
1323int ref_exists(const char *refname)
1324{
1325        unsigned char sha1[20];
1326        return !!resolve_ref_unsafe(refname, sha1, 1, NULL);
1327}
1328
1329static int filter_refs(const char *refname, const unsigned char *sha1, int flags,
1330                       void *data)
1331{
1332        struct ref_filter *filter = (struct ref_filter *)data;
1333        if (fnmatch(filter->pattern, refname, 0))
1334                return 0;
1335        return filter->fn(refname, sha1, flags, filter->cb_data);
1336}
1337
1338enum peel_status {
1339        /* object was peeled successfully: */
1340        PEEL_PEELED = 0,
1341
1342        /*
1343         * object cannot be peeled because the named object (or an
1344         * object referred to by a tag in the peel chain), does not
1345         * exist.
1346         */
1347        PEEL_INVALID = -1,
1348
1349        /* object cannot be peeled because it is not a tag: */
1350        PEEL_NON_TAG = -2,
1351
1352        /* ref_entry contains no peeled value because it is a symref: */
1353        PEEL_IS_SYMREF = -3,
1354
1355        /*
1356         * ref_entry cannot be peeled because it is broken (i.e., the
1357         * symbolic reference cannot even be resolved to an object
1358         * name):
1359         */
1360        PEEL_BROKEN = -4
1361};
1362
1363/*
1364 * Peel the named object; i.e., if the object is a tag, resolve the
1365 * tag recursively until a non-tag is found.  If successful, store the
1366 * result to sha1 and return PEEL_PEELED.  If the object is not a tag
1367 * or is not valid, return PEEL_NON_TAG or PEEL_INVALID, respectively,
1368 * and leave sha1 unchanged.
1369 */
1370static enum peel_status peel_object(const unsigned char *name, unsigned char *sha1)
1371{
1372        struct object *o = lookup_unknown_object(name);
1373
1374        if (o->type == OBJ_NONE) {
1375                int type = sha1_object_info(name, NULL);
1376                if (type < 0)
1377                        return PEEL_INVALID;
1378                o->type = type;
1379        }
1380
1381        if (o->type != OBJ_TAG)
1382                return PEEL_NON_TAG;
1383
1384        o = deref_tag_noverify(o);
1385        if (!o)
1386                return PEEL_INVALID;
1387
1388        hashcpy(sha1, o->sha1);
1389        return PEEL_PEELED;
1390}
1391
1392/*
1393 * Peel the entry (if possible) and return its new peel_status.
1394 */
1395static enum peel_status peel_entry(struct ref_entry *entry)
1396{
1397        enum peel_status status;
1398
1399        if (entry->flag & REF_KNOWS_PEELED)
1400                return is_null_sha1(entry->u.value.peeled) ?
1401                        PEEL_NON_TAG : PEEL_PEELED;
1402        if (entry->flag & REF_ISBROKEN)
1403                return PEEL_BROKEN;
1404        if (entry->flag & REF_ISSYMREF)
1405                return PEEL_IS_SYMREF;
1406
1407        status = peel_object(entry->u.value.sha1, entry->u.value.peeled);
1408        if (status == PEEL_PEELED || status == PEEL_NON_TAG)
1409                entry->flag |= REF_KNOWS_PEELED;
1410        return status;
1411}
1412
1413int peel_ref(const char *refname, unsigned char *sha1)
1414{
1415        int flag;
1416        unsigned char base[20];
1417
1418        if (current_ref && (current_ref->name == refname
1419                            || !strcmp(current_ref->name, refname))) {
1420                if (peel_entry(current_ref))
1421                        return -1;
1422                hashcpy(sha1, current_ref->u.value.peeled);
1423                return 0;
1424        }
1425
1426        if (read_ref_full(refname, base, 1, &flag))
1427                return -1;
1428
1429        /*
1430         * If the reference is packed, read its ref_entry from the
1431         * cache in the hope that we already know its peeled value.
1432         * We only try this optimization on packed references because
1433         * (a) forcing the filling of the loose reference cache could
1434         * be expensive and (b) loose references anyway usually do not
1435         * have REF_KNOWS_PEELED.
1436         */
1437        if (flag & REF_ISPACKED) {
1438                struct ref_entry *r = get_packed_ref(refname);
1439                if (r) {
1440                        if (peel_entry(r))
1441                                return -1;
1442                        hashcpy(sha1, r->u.value.peeled);
1443                        return 0;
1444                }
1445        }
1446
1447        return peel_object(base, sha1);
1448}
1449
1450struct warn_if_dangling_data {
1451        FILE *fp;
1452        const char *refname;
1453        const char *msg_fmt;
1454};
1455
1456static int warn_if_dangling_symref(const char *refname, const unsigned char *sha1,
1457                                   int flags, void *cb_data)
1458{
1459        struct warn_if_dangling_data *d = cb_data;
1460        const char *resolves_to;
1461        unsigned char junk[20];
1462
1463        if (!(flags & REF_ISSYMREF))
1464                return 0;
1465
1466        resolves_to = resolve_ref_unsafe(refname, junk, 0, NULL);
1467        if (!resolves_to || strcmp(resolves_to, d->refname))
1468                return 0;
1469
1470        fprintf(d->fp, d->msg_fmt, refname);
1471        fputc('\n', d->fp);
1472        return 0;
1473}
1474
1475void warn_dangling_symref(FILE *fp, const char *msg_fmt, const char *refname)
1476{
1477        struct warn_if_dangling_data data;
1478
1479        data.fp = fp;
1480        data.refname = refname;
1481        data.msg_fmt = msg_fmt;
1482        for_each_rawref(warn_if_dangling_symref, &data);
1483}
1484
1485/*
1486 * Call fn for each reference in the specified submodule, omitting
1487 * references not in the containing_dir of base.  fn is called for all
1488 * references, including broken ones.  If fn ever returns a non-zero
1489 * value, stop the iteration and return that value; otherwise, return
1490 * 0.
1491 */
1492static int do_for_each_entry(const char *submodule, const char *base,
1493                             each_ref_entry_fn fn, void *cb_data)
1494{
1495        struct ref_cache *refs = get_ref_cache(submodule);
1496        struct ref_dir *packed_dir = get_packed_refs(refs);
1497        struct ref_dir *loose_dir = get_loose_refs(refs);
1498        int retval = 0;
1499
1500        if (base && *base) {
1501                packed_dir = find_containing_dir(packed_dir, base, 0);
1502                loose_dir = find_containing_dir(loose_dir, base, 0);
1503        }
1504
1505        if (packed_dir && loose_dir) {
1506                sort_ref_dir(packed_dir);
1507                sort_ref_dir(loose_dir);
1508                retval = do_for_each_entry_in_dirs(
1509                                packed_dir, loose_dir, fn, cb_data);
1510        } else if (packed_dir) {
1511                sort_ref_dir(packed_dir);
1512                retval = do_for_each_entry_in_dir(
1513                                packed_dir, 0, fn, cb_data);
1514        } else if (loose_dir) {
1515                sort_ref_dir(loose_dir);
1516                retval = do_for_each_entry_in_dir(
1517                                loose_dir, 0, fn, cb_data);
1518        }
1519
1520        return retval;
1521}
1522
1523/*
1524 * Call fn for each reference in the specified submodule for which the
1525 * refname begins with base.  If trim is non-zero, then trim that many
1526 * characters off the beginning of each refname before passing the
1527 * refname to fn.  flags can be DO_FOR_EACH_INCLUDE_BROKEN to include
1528 * broken references in the iteration.  If fn ever returns a non-zero
1529 * value, stop the iteration and return that value; otherwise, return
1530 * 0.
1531 */
1532static int do_for_each_ref(const char *submodule, const char *base, each_ref_fn fn,
1533                           int trim, int flags, void *cb_data)
1534{
1535        struct ref_entry_cb data;
1536        data.base = base;
1537        data.trim = trim;
1538        data.flags = flags;
1539        data.fn = fn;
1540        data.cb_data = cb_data;
1541
1542        return do_for_each_entry(submodule, base, do_one_ref, &data);
1543}
1544
1545static int do_head_ref(const char *submodule, each_ref_fn fn, void *cb_data)
1546{
1547        unsigned char sha1[20];
1548        int flag;
1549
1550        if (submodule) {
1551                if (resolve_gitlink_ref(submodule, "HEAD", sha1) == 0)
1552                        return fn("HEAD", sha1, 0, cb_data);
1553
1554                return 0;
1555        }
1556
1557        if (!read_ref_full("HEAD", sha1, 1, &flag))
1558                return fn("HEAD", sha1, flag, cb_data);
1559
1560        return 0;
1561}
1562
1563int head_ref(each_ref_fn fn, void *cb_data)
1564{
1565        return do_head_ref(NULL, fn, cb_data);
1566}
1567
1568int head_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
1569{
1570        return do_head_ref(submodule, fn, cb_data);
1571}
1572
1573int for_each_ref(each_ref_fn fn, void *cb_data)
1574{
1575        return do_for_each_ref(NULL, "", fn, 0, 0, cb_data);
1576}
1577
1578int for_each_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
1579{
1580        return do_for_each_ref(submodule, "", fn, 0, 0, cb_data);
1581}
1582
1583int for_each_ref_in(const char *prefix, each_ref_fn fn, void *cb_data)
1584{
1585        return do_for_each_ref(NULL, prefix, fn, strlen(prefix), 0, cb_data);
1586}
1587
1588int for_each_ref_in_submodule(const char *submodule, const char *prefix,
1589                each_ref_fn fn, void *cb_data)
1590{
1591        return do_for_each_ref(submodule, prefix, fn, strlen(prefix), 0, cb_data);
1592}
1593
1594int for_each_tag_ref(each_ref_fn fn, void *cb_data)
1595{
1596        return for_each_ref_in("refs/tags/", fn, cb_data);
1597}
1598
1599int for_each_tag_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
1600{
1601        return for_each_ref_in_submodule(submodule, "refs/tags/", fn, cb_data);
1602}
1603
1604int for_each_branch_ref(each_ref_fn fn, void *cb_data)
1605{
1606        return for_each_ref_in("refs/heads/", fn, cb_data);
1607}
1608
1609int for_each_branch_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
1610{
1611        return for_each_ref_in_submodule(submodule, "refs/heads/", fn, cb_data);
1612}
1613
1614int for_each_remote_ref(each_ref_fn fn, void *cb_data)
1615{
1616        return for_each_ref_in("refs/remotes/", fn, cb_data);
1617}
1618
1619int for_each_remote_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
1620{
1621        return for_each_ref_in_submodule(submodule, "refs/remotes/", fn, cb_data);
1622}
1623
1624int for_each_replace_ref(each_ref_fn fn, void *cb_data)
1625{
1626        return do_for_each_ref(NULL, "refs/replace/", fn, 13, 0, cb_data);
1627}
1628
1629int head_ref_namespaced(each_ref_fn fn, void *cb_data)
1630{
1631        struct strbuf buf = STRBUF_INIT;
1632        int ret = 0;
1633        unsigned char sha1[20];
1634        int flag;
1635
1636        strbuf_addf(&buf, "%sHEAD", get_git_namespace());
1637        if (!read_ref_full(buf.buf, sha1, 1, &flag))
1638                ret = fn(buf.buf, sha1, flag, cb_data);
1639        strbuf_release(&buf);
1640
1641        return ret;
1642}
1643
1644int for_each_namespaced_ref(each_ref_fn fn, void *cb_data)
1645{
1646        struct strbuf buf = STRBUF_INIT;
1647        int ret;
1648        strbuf_addf(&buf, "%srefs/", get_git_namespace());
1649        ret = do_for_each_ref(NULL, buf.buf, fn, 0, 0, cb_data);
1650        strbuf_release(&buf);
1651        return ret;
1652}
1653
1654int for_each_glob_ref_in(each_ref_fn fn, const char *pattern,
1655        const char *prefix, void *cb_data)
1656{
1657        struct strbuf real_pattern = STRBUF_INIT;
1658        struct ref_filter filter;
1659        int ret;
1660
1661        if (!prefix && prefixcmp(pattern, "refs/"))
1662                strbuf_addstr(&real_pattern, "refs/");
1663        else if (prefix)
1664                strbuf_addstr(&real_pattern, prefix);
1665        strbuf_addstr(&real_pattern, pattern);
1666
1667        if (!has_glob_specials(pattern)) {
1668                /* Append implied '/' '*' if not present. */
1669                if (real_pattern.buf[real_pattern.len - 1] != '/')
1670                        strbuf_addch(&real_pattern, '/');
1671                /* No need to check for '*', there is none. */
1672                strbuf_addch(&real_pattern, '*');
1673        }
1674
1675        filter.pattern = real_pattern.buf;
1676        filter.fn = fn;
1677        filter.cb_data = cb_data;
1678        ret = for_each_ref(filter_refs, &filter);
1679
1680        strbuf_release(&real_pattern);
1681        return ret;
1682}
1683
1684int for_each_glob_ref(each_ref_fn fn, const char *pattern, void *cb_data)
1685{
1686        return for_each_glob_ref_in(fn, pattern, NULL, cb_data);
1687}
1688
1689int for_each_rawref(each_ref_fn fn, void *cb_data)
1690{
1691        return do_for_each_ref(NULL, "", fn, 0,
1692                               DO_FOR_EACH_INCLUDE_BROKEN, cb_data);
1693}
1694
1695const char *prettify_refname(const char *name)
1696{
1697        return name + (
1698                !prefixcmp(name, "refs/heads/") ? 11 :
1699                !prefixcmp(name, "refs/tags/") ? 10 :
1700                !prefixcmp(name, "refs/remotes/") ? 13 :
1701                0);
1702}
1703
1704const char *ref_rev_parse_rules[] = {
1705        "%.*s",
1706        "refs/%.*s",
1707        "refs/tags/%.*s",
1708        "refs/heads/%.*s",
1709        "refs/remotes/%.*s",
1710        "refs/remotes/%.*s/HEAD",
1711        NULL
1712};
1713
1714int refname_match(const char *abbrev_name, const char *full_name, const char **rules)
1715{
1716        const char **p;
1717        const int abbrev_name_len = strlen(abbrev_name);
1718
1719        for (p = rules; *p; p++) {
1720                if (!strcmp(full_name, mkpath(*p, abbrev_name_len, abbrev_name))) {
1721                        return 1;
1722                }
1723        }
1724
1725        return 0;
1726}
1727
1728static struct ref_lock *verify_lock(struct ref_lock *lock,
1729        const unsigned char *old_sha1, int mustexist)
1730{
1731        if (read_ref_full(lock->ref_name, lock->old_sha1, mustexist, NULL)) {
1732                error("Can't verify ref %s", lock->ref_name);
1733                unlock_ref(lock);
1734                return NULL;
1735        }
1736        if (hashcmp(lock->old_sha1, old_sha1)) {
1737                error("Ref %s is at %s but expected %s", lock->ref_name,
1738                        sha1_to_hex(lock->old_sha1), sha1_to_hex(old_sha1));
1739                unlock_ref(lock);
1740                return NULL;
1741        }
1742        return lock;
1743}
1744
1745static int remove_empty_directories(const char *file)
1746{
1747        /* we want to create a file but there is a directory there;
1748         * if that is an empty directory (or a directory that contains
1749         * only empty directories), remove them.
1750         */
1751        struct strbuf path;
1752        int result;
1753
1754        strbuf_init(&path, 20);
1755        strbuf_addstr(&path, file);
1756
1757        result = remove_dir_recursively(&path, REMOVE_DIR_EMPTY_ONLY);
1758
1759        strbuf_release(&path);
1760
1761        return result;
1762}
1763
1764/*
1765 * *string and *len will only be substituted, and *string returned (for
1766 * later free()ing) if the string passed in is a magic short-hand form
1767 * to name a branch.
1768 */
1769static char *substitute_branch_name(const char **string, int *len)
1770{
1771        struct strbuf buf = STRBUF_INIT;
1772        int ret = interpret_branch_name(*string, &buf);
1773
1774        if (ret == *len) {
1775                size_t size;
1776                *string = strbuf_detach(&buf, &size);
1777                *len = size;
1778                return (char *)*string;
1779        }
1780
1781        return NULL;
1782}
1783
1784int dwim_ref(const char *str, int len, unsigned char *sha1, char **ref)
1785{
1786        char *last_branch = substitute_branch_name(&str, &len);
1787        const char **p, *r;
1788        int refs_found = 0;
1789
1790        *ref = NULL;
1791        for (p = ref_rev_parse_rules; *p; p++) {
1792                char fullref[PATH_MAX];
1793                unsigned char sha1_from_ref[20];
1794                unsigned char *this_result;
1795                int flag;
1796
1797                this_result = refs_found ? sha1_from_ref : sha1;
1798                mksnpath(fullref, sizeof(fullref), *p, len, str);
1799                r = resolve_ref_unsafe(fullref, this_result, 1, &flag);
1800                if (r) {
1801                        if (!refs_found++)
1802                                *ref = xstrdup(r);
1803                        if (!warn_ambiguous_refs)
1804                                break;
1805                } else if ((flag & REF_ISSYMREF) && strcmp(fullref, "HEAD")) {
1806                        warning("ignoring dangling symref %s.", fullref);
1807                } else if ((flag & REF_ISBROKEN) && strchr(fullref, '/')) {
1808                        warning("ignoring broken ref %s.", fullref);
1809                }
1810        }
1811        free(last_branch);
1812        return refs_found;
1813}
1814
1815int dwim_log(const char *str, int len, unsigned char *sha1, char **log)
1816{
1817        char *last_branch = substitute_branch_name(&str, &len);
1818        const char **p;
1819        int logs_found = 0;
1820
1821        *log = NULL;
1822        for (p = ref_rev_parse_rules; *p; p++) {
1823                struct stat st;
1824                unsigned char hash[20];
1825                char path[PATH_MAX];
1826                const char *ref, *it;
1827
1828                mksnpath(path, sizeof(path), *p, len, str);
1829                ref = resolve_ref_unsafe(path, hash, 1, NULL);
1830                if (!ref)
1831                        continue;
1832                if (!stat(git_path("logs/%s", path), &st) &&
1833                    S_ISREG(st.st_mode))
1834                        it = path;
1835                else if (strcmp(ref, path) &&
1836                         !stat(git_path("logs/%s", ref), &st) &&
1837                         S_ISREG(st.st_mode))
1838                        it = ref;
1839                else
1840                        continue;
1841                if (!logs_found++) {
1842                        *log = xstrdup(it);
1843                        hashcpy(sha1, hash);
1844                }
1845                if (!warn_ambiguous_refs)
1846                        break;
1847        }
1848        free(last_branch);
1849        return logs_found;
1850}
1851
1852static struct ref_lock *lock_ref_sha1_basic(const char *refname,
1853                                            const unsigned char *old_sha1,
1854                                            int flags, int *type_p)
1855{
1856        char *ref_file;
1857        const char *orig_refname = refname;
1858        struct ref_lock *lock;
1859        int last_errno = 0;
1860        int type, lflags;
1861        int mustexist = (old_sha1 && !is_null_sha1(old_sha1));
1862        int missing = 0;
1863
1864        lock = xcalloc(1, sizeof(struct ref_lock));
1865        lock->lock_fd = -1;
1866
1867        refname = resolve_ref_unsafe(refname, lock->old_sha1, mustexist, &type);
1868        if (!refname && errno == EISDIR) {
1869                /* we are trying to lock foo but we used to
1870                 * have foo/bar which now does not exist;
1871                 * it is normal for the empty directory 'foo'
1872                 * to remain.
1873                 */
1874                ref_file = git_path("%s", orig_refname);
1875                if (remove_empty_directories(ref_file)) {
1876                        last_errno = errno;
1877                        error("there are still refs under '%s'", orig_refname);
1878                        goto error_return;
1879                }
1880                refname = resolve_ref_unsafe(orig_refname, lock->old_sha1, mustexist, &type);
1881        }
1882        if (type_p)
1883            *type_p = type;
1884        if (!refname) {
1885                last_errno = errno;
1886                error("unable to resolve reference %s: %s",
1887                        orig_refname, strerror(errno));
1888                goto error_return;
1889        }
1890        missing = is_null_sha1(lock->old_sha1);
1891        /* When the ref did not exist and we are creating it,
1892         * make sure there is no existing ref that is packed
1893         * whose name begins with our refname, nor a ref whose
1894         * name is a proper prefix of our refname.
1895         */
1896        if (missing &&
1897             !is_refname_available(refname, NULL, get_packed_refs(get_ref_cache(NULL)))) {
1898                last_errno = ENOTDIR;
1899                goto error_return;
1900        }
1901
1902        lock->lk = xcalloc(1, sizeof(struct lock_file));
1903
1904        lflags = LOCK_DIE_ON_ERROR;
1905        if (flags & REF_NODEREF) {
1906                refname = orig_refname;
1907                lflags |= LOCK_NODEREF;
1908        }
1909        lock->ref_name = xstrdup(refname);
1910        lock->orig_ref_name = xstrdup(orig_refname);
1911        ref_file = git_path("%s", refname);
1912        if (missing)
1913                lock->force_write = 1;
1914        if ((flags & REF_NODEREF) && (type & REF_ISSYMREF))
1915                lock->force_write = 1;
1916
1917        if (safe_create_leading_directories(ref_file)) {
1918                last_errno = errno;
1919                error("unable to create directory for %s", ref_file);
1920                goto error_return;
1921        }
1922
1923        lock->lock_fd = hold_lock_file_for_update(lock->lk, ref_file, lflags);
1924        return old_sha1 ? verify_lock(lock, old_sha1, mustexist) : lock;
1925
1926 error_return:
1927        unlock_ref(lock);
1928        errno = last_errno;
1929        return NULL;
1930}
1931
1932struct ref_lock *lock_ref_sha1(const char *refname, const unsigned char *old_sha1)
1933{
1934        char refpath[PATH_MAX];
1935        if (check_refname_format(refname, 0))
1936                return NULL;
1937        strcpy(refpath, mkpath("refs/%s", refname));
1938        return lock_ref_sha1_basic(refpath, old_sha1, 0, NULL);
1939}
1940
1941struct ref_lock *lock_any_ref_for_update(const char *refname,
1942                                         const unsigned char *old_sha1, int flags)
1943{
1944        if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL))
1945                return NULL;
1946        return lock_ref_sha1_basic(refname, old_sha1, flags, NULL);
1947}
1948
1949static int repack_ref_fn(struct ref_entry *entry, void *cb_data)
1950{
1951        int *fd = cb_data;
1952        char line[PATH_MAX + 100];
1953        int len;
1954
1955        if (entry->flag & REF_ISBROKEN) {
1956                /* This shouldn't happen to packed refs. */
1957                error("%s is broken!", entry->name);
1958                return 0;
1959        }
1960        if (!has_sha1_file(entry->u.value.sha1)) {
1961                unsigned char sha1[20];
1962                int flags;
1963
1964                if (read_ref_full(entry->name, sha1, 0, &flags))
1965                        /* We should at least have found the packed ref. */
1966                        die("Internal error");
1967                if ((flags & REF_ISSYMREF) || !(flags & REF_ISPACKED))
1968                        /*
1969                         * This packed reference is overridden by a
1970                         * loose reference, so it is OK that its value
1971                         * is no longer valid; for example, it might
1972                         * refer to an object that has been garbage
1973                         * collected.  For this purpose we don't even
1974                         * care whether the loose reference itself is
1975                         * invalid, broken, symbolic, etc.  Silently
1976                         * omit the packed reference from the output.
1977                         */
1978                        return 0;
1979                /*
1980                 * There is no overriding loose reference, so the fact
1981                 * that this reference doesn't refer to a valid object
1982                 * indicates some kind of repository corruption.
1983                 * Report the problem, then omit the reference from
1984                 * the output.
1985                 */
1986                error("%s does not point to a valid object!", entry->name);
1987                return 0;
1988        }
1989
1990        len = snprintf(line, sizeof(line), "%s %s\n",
1991                       sha1_to_hex(entry->u.value.sha1), entry->name);
1992        /* this should not happen but just being defensive */
1993        if (len > sizeof(line))
1994                die("too long a refname '%s'", entry->name);
1995        write_or_die(*fd, line, len);
1996        return 0;
1997}
1998
1999static struct lock_file packlock;
2000
2001static int repack_without_ref(const char *refname)
2002{
2003        int fd;
2004        struct ref_cache *refs = get_ref_cache(NULL);
2005        struct ref_dir *packed;
2006
2007        if (!get_packed_ref(refname))
2008                return 0; /* refname does not exist in packed refs */
2009
2010        fd = hold_lock_file_for_update(&packlock, git_path("packed-refs"), 0);
2011        if (fd < 0) {
2012                unable_to_lock_error(git_path("packed-refs"), errno);
2013                return error("cannot delete '%s' from packed refs", refname);
2014        }
2015        clear_packed_ref_cache(refs);
2016        packed = get_packed_refs(refs);
2017        /* Remove refname from the cache. */
2018        if (remove_entry(packed, refname) == -1) {
2019                /*
2020                 * The packed entry disappeared while we were
2021                 * acquiring the lock.
2022                 */
2023                rollback_lock_file(&packlock);
2024                return 0;
2025        }
2026        do_for_each_entry_in_dir(packed, 0, repack_ref_fn, &fd);
2027        return commit_lock_file(&packlock);
2028}
2029
2030int delete_ref(const char *refname, const unsigned char *sha1, int delopt)
2031{
2032        struct ref_lock *lock;
2033        int err, i = 0, ret = 0, flag = 0;
2034
2035        lock = lock_ref_sha1_basic(refname, sha1, delopt, &flag);
2036        if (!lock)
2037                return 1;
2038        if (!(flag & REF_ISPACKED) || flag & REF_ISSYMREF) {
2039                /* loose */
2040                i = strlen(lock->lk->filename) - 5; /* .lock */
2041                lock->lk->filename[i] = 0;
2042                err = unlink_or_warn(lock->lk->filename);
2043                if (err && errno != ENOENT)
2044                        ret = 1;
2045
2046                lock->lk->filename[i] = '.';
2047        }
2048        /* removing the loose one could have resurrected an earlier
2049         * packed one.  Also, if it was not loose we need to repack
2050         * without it.
2051         */
2052        ret |= repack_without_ref(lock->ref_name);
2053
2054        unlink_or_warn(git_path("logs/%s", lock->ref_name));
2055        clear_loose_ref_cache(get_ref_cache(NULL));
2056        unlock_ref(lock);
2057        return ret;
2058}
2059
2060/*
2061 * People using contrib's git-new-workdir have .git/logs/refs ->
2062 * /some/other/path/.git/logs/refs, and that may live on another device.
2063 *
2064 * IOW, to avoid cross device rename errors, the temporary renamed log must
2065 * live into logs/refs.
2066 */
2067#define TMP_RENAMED_LOG  "logs/refs/.tmp-renamed-log"
2068
2069int rename_ref(const char *oldrefname, const char *newrefname, const char *logmsg)
2070{
2071        unsigned char sha1[20], orig_sha1[20];
2072        int flag = 0, logmoved = 0;
2073        struct ref_lock *lock;
2074        struct stat loginfo;
2075        int log = !lstat(git_path("logs/%s", oldrefname), &loginfo);
2076        const char *symref = NULL;
2077        struct ref_cache *refs = get_ref_cache(NULL);
2078
2079        if (log && S_ISLNK(loginfo.st_mode))
2080                return error("reflog for %s is a symlink", oldrefname);
2081
2082        symref = resolve_ref_unsafe(oldrefname, orig_sha1, 1, &flag);
2083        if (flag & REF_ISSYMREF)
2084                return error("refname %s is a symbolic ref, renaming it is not supported",
2085                        oldrefname);
2086        if (!symref)
2087                return error("refname %s not found", oldrefname);
2088
2089        if (!is_refname_available(newrefname, oldrefname, get_packed_refs(refs)))
2090                return 1;
2091
2092        if (!is_refname_available(newrefname, oldrefname, get_loose_refs(refs)))
2093                return 1;
2094
2095        if (log && rename(git_path("logs/%s", oldrefname), git_path(TMP_RENAMED_LOG)))
2096                return error("unable to move logfile logs/%s to "TMP_RENAMED_LOG": %s",
2097                        oldrefname, strerror(errno));
2098
2099        if (delete_ref(oldrefname, orig_sha1, REF_NODEREF)) {
2100                error("unable to delete old %s", oldrefname);
2101                goto rollback;
2102        }
2103
2104        if (!read_ref_full(newrefname, sha1, 1, &flag) &&
2105            delete_ref(newrefname, sha1, REF_NODEREF)) {
2106                if (errno==EISDIR) {
2107                        if (remove_empty_directories(git_path("%s", newrefname))) {
2108                                error("Directory not empty: %s", newrefname);
2109                                goto rollback;
2110                        }
2111                } else {
2112                        error("unable to delete existing %s", newrefname);
2113                        goto rollback;
2114                }
2115        }
2116
2117        if (log && safe_create_leading_directories(git_path("logs/%s", newrefname))) {
2118                error("unable to create directory for %s", newrefname);
2119                goto rollback;
2120        }
2121
2122 retry:
2123        if (log && rename(git_path(TMP_RENAMED_LOG), git_path("logs/%s", newrefname))) {
2124                if (errno==EISDIR || errno==ENOTDIR) {
2125                        /*
2126                         * rename(a, b) when b is an existing
2127                         * directory ought to result in ISDIR, but
2128                         * Solaris 5.8 gives ENOTDIR.  Sheesh.
2129                         */
2130                        if (remove_empty_directories(git_path("logs/%s", newrefname))) {
2131                                error("Directory not empty: logs/%s", newrefname);
2132                                goto rollback;
2133                        }
2134                        goto retry;
2135                } else {
2136                        error("unable to move logfile "TMP_RENAMED_LOG" to logs/%s: %s",
2137                                newrefname, strerror(errno));
2138                        goto rollback;
2139                }
2140        }
2141        logmoved = log;
2142
2143        lock = lock_ref_sha1_basic(newrefname, NULL, 0, NULL);
2144        if (!lock) {
2145                error("unable to lock %s for update", newrefname);
2146                goto rollback;
2147        }
2148        lock->force_write = 1;
2149        hashcpy(lock->old_sha1, orig_sha1);
2150        if (write_ref_sha1(lock, orig_sha1, logmsg)) {
2151                error("unable to write current sha1 into %s", newrefname);
2152                goto rollback;
2153        }
2154
2155        return 0;
2156
2157 rollback:
2158        lock = lock_ref_sha1_basic(oldrefname, NULL, 0, NULL);
2159        if (!lock) {
2160                error("unable to lock %s for rollback", oldrefname);
2161                goto rollbacklog;
2162        }
2163
2164        lock->force_write = 1;
2165        flag = log_all_ref_updates;
2166        log_all_ref_updates = 0;
2167        if (write_ref_sha1(lock, orig_sha1, NULL))
2168                error("unable to write current sha1 into %s", oldrefname);
2169        log_all_ref_updates = flag;
2170
2171 rollbacklog:
2172        if (logmoved && rename(git_path("logs/%s", newrefname), git_path("logs/%s", oldrefname)))
2173                error("unable to restore logfile %s from %s: %s",
2174                        oldrefname, newrefname, strerror(errno));
2175        if (!logmoved && log &&
2176            rename(git_path(TMP_RENAMED_LOG), git_path("logs/%s", oldrefname)))
2177                error("unable to restore logfile %s from "TMP_RENAMED_LOG": %s",
2178                        oldrefname, strerror(errno));
2179
2180        return 1;
2181}
2182
2183int close_ref(struct ref_lock *lock)
2184{
2185        if (close_lock_file(lock->lk))
2186                return -1;
2187        lock->lock_fd = -1;
2188        return 0;
2189}
2190
2191int commit_ref(struct ref_lock *lock)
2192{
2193        if (commit_lock_file(lock->lk))
2194                return -1;
2195        lock->lock_fd = -1;
2196        return 0;
2197}
2198
2199void unlock_ref(struct ref_lock *lock)
2200{
2201        /* Do not free lock->lk -- atexit() still looks at them */
2202        if (lock->lk)
2203                rollback_lock_file(lock->lk);
2204        free(lock->ref_name);
2205        free(lock->orig_ref_name);
2206        free(lock);
2207}
2208
2209/*
2210 * copy the reflog message msg to buf, which has been allocated sufficiently
2211 * large, while cleaning up the whitespaces.  Especially, convert LF to space,
2212 * because reflog file is one line per entry.
2213 */
2214static int copy_msg(char *buf, const char *msg)
2215{
2216        char *cp = buf;
2217        char c;
2218        int wasspace = 1;
2219
2220        *cp++ = '\t';
2221        while ((c = *msg++)) {
2222                if (wasspace && isspace(c))
2223                        continue;
2224                wasspace = isspace(c);
2225                if (wasspace)
2226                        c = ' ';
2227                *cp++ = c;
2228        }
2229        while (buf < cp && isspace(cp[-1]))
2230                cp--;
2231        *cp++ = '\n';
2232        return cp - buf;
2233}
2234
2235int log_ref_setup(const char *refname, char *logfile, int bufsize)
2236{
2237        int logfd, oflags = O_APPEND | O_WRONLY;
2238
2239        git_snpath(logfile, bufsize, "logs/%s", refname);
2240        if (log_all_ref_updates &&
2241            (!prefixcmp(refname, "refs/heads/") ||
2242             !prefixcmp(refname, "refs/remotes/") ||
2243             !prefixcmp(refname, "refs/notes/") ||
2244             !strcmp(refname, "HEAD"))) {
2245                if (safe_create_leading_directories(logfile) < 0)
2246                        return error("unable to create directory for %s",
2247                                     logfile);
2248                oflags |= O_CREAT;
2249        }
2250
2251        logfd = open(logfile, oflags, 0666);
2252        if (logfd < 0) {
2253                if (!(oflags & O_CREAT) && errno == ENOENT)
2254                        return 0;
2255
2256                if ((oflags & O_CREAT) && errno == EISDIR) {
2257                        if (remove_empty_directories(logfile)) {
2258                                return error("There are still logs under '%s'",
2259                                             logfile);
2260                        }
2261                        logfd = open(logfile, oflags, 0666);
2262                }
2263
2264                if (logfd < 0)
2265                        return error("Unable to append to %s: %s",
2266                                     logfile, strerror(errno));
2267        }
2268
2269        adjust_shared_perm(logfile);
2270        close(logfd);
2271        return 0;
2272}
2273
2274static int log_ref_write(const char *refname, const unsigned char *old_sha1,
2275                         const unsigned char *new_sha1, const char *msg)
2276{
2277        int logfd, result, written, oflags = O_APPEND | O_WRONLY;
2278        unsigned maxlen, len;
2279        int msglen;
2280        char log_file[PATH_MAX];
2281        char *logrec;
2282        const char *committer;
2283
2284        if (log_all_ref_updates < 0)
2285                log_all_ref_updates = !is_bare_repository();
2286
2287        result = log_ref_setup(refname, log_file, sizeof(log_file));
2288        if (result)
2289                return result;
2290
2291        logfd = open(log_file, oflags);
2292        if (logfd < 0)
2293                return 0;
2294        msglen = msg ? strlen(msg) : 0;
2295        committer = git_committer_info(0);
2296        maxlen = strlen(committer) + msglen + 100;
2297        logrec = xmalloc(maxlen);
2298        len = sprintf(logrec, "%s %s %s\n",
2299                      sha1_to_hex(old_sha1),
2300                      sha1_to_hex(new_sha1),
2301                      committer);
2302        if (msglen)
2303                len += copy_msg(logrec + len - 1, msg) - 1;
2304        written = len <= maxlen ? write_in_full(logfd, logrec, len) : -1;
2305        free(logrec);
2306        if (close(logfd) != 0 || written != len)
2307                return error("Unable to append to %s", log_file);
2308        return 0;
2309}
2310
2311static int is_branch(const char *refname)
2312{
2313        return !strcmp(refname, "HEAD") || !prefixcmp(refname, "refs/heads/");
2314}
2315
2316int write_ref_sha1(struct ref_lock *lock,
2317        const unsigned char *sha1, const char *logmsg)
2318{
2319        static char term = '\n';
2320        struct object *o;
2321
2322        if (!lock)
2323                return -1;
2324        if (!lock->force_write && !hashcmp(lock->old_sha1, sha1)) {
2325                unlock_ref(lock);
2326                return 0;
2327        }
2328        o = parse_object(sha1);
2329        if (!o) {
2330                error("Trying to write ref %s with nonexistent object %s",
2331                        lock->ref_name, sha1_to_hex(sha1));
2332                unlock_ref(lock);
2333                return -1;
2334        }
2335        if (o->type != OBJ_COMMIT && is_branch(lock->ref_name)) {
2336                error("Trying to write non-commit object %s to branch %s",
2337                        sha1_to_hex(sha1), lock->ref_name);
2338                unlock_ref(lock);
2339                return -1;
2340        }
2341        if (write_in_full(lock->lock_fd, sha1_to_hex(sha1), 40) != 40 ||
2342            write_in_full(lock->lock_fd, &term, 1) != 1
2343                || close_ref(lock) < 0) {
2344                error("Couldn't write %s", lock->lk->filename);
2345                unlock_ref(lock);
2346                return -1;
2347        }
2348        clear_loose_ref_cache(get_ref_cache(NULL));
2349        if (log_ref_write(lock->ref_name, lock->old_sha1, sha1, logmsg) < 0 ||
2350            (strcmp(lock->ref_name, lock->orig_ref_name) &&
2351             log_ref_write(lock->orig_ref_name, lock->old_sha1, sha1, logmsg) < 0)) {
2352                unlock_ref(lock);
2353                return -1;
2354        }
2355        if (strcmp(lock->orig_ref_name, "HEAD") != 0) {
2356                /*
2357                 * Special hack: If a branch is updated directly and HEAD
2358                 * points to it (may happen on the remote side of a push
2359                 * for example) then logically the HEAD reflog should be
2360                 * updated too.
2361                 * A generic solution implies reverse symref information,
2362                 * but finding all symrefs pointing to the given branch
2363                 * would be rather costly for this rare event (the direct
2364                 * update of a branch) to be worth it.  So let's cheat and
2365                 * check with HEAD only which should cover 99% of all usage
2366                 * scenarios (even 100% of the default ones).
2367                 */
2368                unsigned char head_sha1[20];
2369                int head_flag;
2370                const char *head_ref;
2371                head_ref = resolve_ref_unsafe("HEAD", head_sha1, 1, &head_flag);
2372                if (head_ref && (head_flag & REF_ISSYMREF) &&
2373                    !strcmp(head_ref, lock->ref_name))
2374                        log_ref_write("HEAD", lock->old_sha1, sha1, logmsg);
2375        }
2376        if (commit_ref(lock)) {
2377                error("Couldn't set %s", lock->ref_name);
2378                unlock_ref(lock);
2379                return -1;
2380        }
2381        unlock_ref(lock);
2382        return 0;
2383}
2384
2385int create_symref(const char *ref_target, const char *refs_heads_master,
2386                  const char *logmsg)
2387{
2388        const char *lockpath;
2389        char ref[1000];
2390        int fd, len, written;
2391        char *git_HEAD = git_pathdup("%s", ref_target);
2392        unsigned char old_sha1[20], new_sha1[20];
2393
2394        if (logmsg && read_ref(ref_target, old_sha1))
2395                hashclr(old_sha1);
2396
2397        if (safe_create_leading_directories(git_HEAD) < 0)
2398                return error("unable to create directory for %s", git_HEAD);
2399
2400#ifndef NO_SYMLINK_HEAD
2401        if (prefer_symlink_refs) {
2402                unlink(git_HEAD);
2403                if (!symlink(refs_heads_master, git_HEAD))
2404                        goto done;
2405                fprintf(stderr, "no symlink - falling back to symbolic ref\n");
2406        }
2407#endif
2408
2409        len = snprintf(ref, sizeof(ref), "ref: %s\n", refs_heads_master);
2410        if (sizeof(ref) <= len) {
2411                error("refname too long: %s", refs_heads_master);
2412                goto error_free_return;
2413        }
2414        lockpath = mkpath("%s.lock", git_HEAD);
2415        fd = open(lockpath, O_CREAT | O_EXCL | O_WRONLY, 0666);
2416        if (fd < 0) {
2417                error("Unable to open %s for writing", lockpath);
2418                goto error_free_return;
2419        }
2420        written = write_in_full(fd, ref, len);
2421        if (close(fd) != 0 || written != len) {
2422                error("Unable to write to %s", lockpath);
2423                goto error_unlink_return;
2424        }
2425        if (rename(lockpath, git_HEAD) < 0) {
2426                error("Unable to create %s", git_HEAD);
2427                goto error_unlink_return;
2428        }
2429        if (adjust_shared_perm(git_HEAD)) {
2430                error("Unable to fix permissions on %s", lockpath);
2431        error_unlink_return:
2432                unlink_or_warn(lockpath);
2433        error_free_return:
2434                free(git_HEAD);
2435                return -1;
2436        }
2437
2438#ifndef NO_SYMLINK_HEAD
2439        done:
2440#endif
2441        if (logmsg && !read_ref(refs_heads_master, new_sha1))
2442                log_ref_write(ref_target, old_sha1, new_sha1, logmsg);
2443
2444        free(git_HEAD);
2445        return 0;
2446}
2447
2448static char *ref_msg(const char *line, const char *endp)
2449{
2450        const char *ep;
2451        line += 82;
2452        ep = memchr(line, '\n', endp - line);
2453        if (!ep)
2454                ep = endp;
2455        return xmemdupz(line, ep - line);
2456}
2457
2458int read_ref_at(const char *refname, unsigned long at_time, int cnt,
2459                unsigned char *sha1, char **msg,
2460                unsigned long *cutoff_time, int *cutoff_tz, int *cutoff_cnt)
2461{
2462        const char *logfile, *logdata, *logend, *rec, *lastgt, *lastrec;
2463        char *tz_c;
2464        int logfd, tz, reccnt = 0;
2465        struct stat st;
2466        unsigned long date;
2467        unsigned char logged_sha1[20];
2468        void *log_mapped;
2469        size_t mapsz;
2470
2471        logfile = git_path("logs/%s", refname);
2472        logfd = open(logfile, O_RDONLY, 0);
2473        if (logfd < 0)
2474                die_errno("Unable to read log '%s'", logfile);
2475        fstat(logfd, &st);
2476        if (!st.st_size)
2477                die("Log %s is empty.", logfile);
2478        mapsz = xsize_t(st.st_size);
2479        log_mapped = xmmap(NULL, mapsz, PROT_READ, MAP_PRIVATE, logfd, 0);
2480        logdata = log_mapped;
2481        close(logfd);
2482
2483        lastrec = NULL;
2484        rec = logend = logdata + st.st_size;
2485        while (logdata < rec) {
2486                reccnt++;
2487                if (logdata < rec && *(rec-1) == '\n')
2488                        rec--;
2489                lastgt = NULL;
2490                while (logdata < rec && *(rec-1) != '\n') {
2491                        rec--;
2492                        if (*rec == '>')
2493                                lastgt = rec;
2494                }
2495                if (!lastgt)
2496                        die("Log %s is corrupt.", logfile);
2497                date = strtoul(lastgt + 1, &tz_c, 10);
2498                if (date <= at_time || cnt == 0) {
2499                        tz = strtoul(tz_c, NULL, 10);
2500                        if (msg)
2501                                *msg = ref_msg(rec, logend);
2502                        if (cutoff_time)
2503                                *cutoff_time = date;
2504                        if (cutoff_tz)
2505                                *cutoff_tz = tz;
2506                        if (cutoff_cnt)
2507                                *cutoff_cnt = reccnt - 1;
2508                        if (lastrec) {
2509                                if (get_sha1_hex(lastrec, logged_sha1))
2510                                        die("Log %s is corrupt.", logfile);
2511                                if (get_sha1_hex(rec + 41, sha1))
2512                                        die("Log %s is corrupt.", logfile);
2513                                if (hashcmp(logged_sha1, sha1)) {
2514                                        warning("Log %s has gap after %s.",
2515                                                logfile, show_date(date, tz, DATE_RFC2822));
2516                                }
2517                        }
2518                        else if (date == at_time) {
2519                                if (get_sha1_hex(rec + 41, sha1))
2520                                        die("Log %s is corrupt.", logfile);
2521                        }
2522                        else {
2523                                if (get_sha1_hex(rec + 41, logged_sha1))
2524                                        die("Log %s is corrupt.", logfile);
2525                                if (hashcmp(logged_sha1, sha1)) {
2526                                        warning("Log %s unexpectedly ended on %s.",
2527                                                logfile, show_date(date, tz, DATE_RFC2822));
2528                                }
2529                        }
2530                        munmap(log_mapped, mapsz);
2531                        return 0;
2532                }
2533                lastrec = rec;
2534                if (cnt > 0)
2535                        cnt--;
2536        }
2537
2538        rec = logdata;
2539        while (rec < logend && *rec != '>' && *rec != '\n')
2540                rec++;
2541        if (rec == logend || *rec == '\n')
2542                die("Log %s is corrupt.", logfile);
2543        date = strtoul(rec + 1, &tz_c, 10);
2544        tz = strtoul(tz_c, NULL, 10);
2545        if (get_sha1_hex(logdata, sha1))
2546                die("Log %s is corrupt.", logfile);
2547        if (is_null_sha1(sha1)) {
2548                if (get_sha1_hex(logdata + 41, sha1))
2549                        die("Log %s is corrupt.", logfile);
2550        }
2551        if (msg)
2552                *msg = ref_msg(logdata, logend);
2553        munmap(log_mapped, mapsz);
2554
2555        if (cutoff_time)
2556                *cutoff_time = date;
2557        if (cutoff_tz)
2558                *cutoff_tz = tz;
2559        if (cutoff_cnt)
2560                *cutoff_cnt = reccnt;
2561        return 1;
2562}
2563
2564int for_each_recent_reflog_ent(const char *refname, each_reflog_ent_fn fn, long ofs, void *cb_data)
2565{
2566        const char *logfile;
2567        FILE *logfp;
2568        struct strbuf sb = STRBUF_INIT;
2569        int ret = 0;
2570
2571        logfile = git_path("logs/%s", refname);
2572        logfp = fopen(logfile, "r");
2573        if (!logfp)
2574                return -1;
2575
2576        if (ofs) {
2577                struct stat statbuf;
2578                if (fstat(fileno(logfp), &statbuf) ||
2579                    statbuf.st_size < ofs ||
2580                    fseek(logfp, -ofs, SEEK_END) ||
2581                    strbuf_getwholeline(&sb, logfp, '\n')) {
2582                        fclose(logfp);
2583                        strbuf_release(&sb);
2584                        return -1;
2585                }
2586        }
2587
2588        while (!strbuf_getwholeline(&sb, logfp, '\n')) {
2589                unsigned char osha1[20], nsha1[20];
2590                char *email_end, *message;
2591                unsigned long timestamp;
2592                int tz;
2593
2594                /* old SP new SP name <email> SP time TAB msg LF */
2595                if (sb.len < 83 || sb.buf[sb.len - 1] != '\n' ||
2596                    get_sha1_hex(sb.buf, osha1) || sb.buf[40] != ' ' ||
2597                    get_sha1_hex(sb.buf + 41, nsha1) || sb.buf[81] != ' ' ||
2598                    !(email_end = strchr(sb.buf + 82, '>')) ||
2599                    email_end[1] != ' ' ||
2600                    !(timestamp = strtoul(email_end + 2, &message, 10)) ||
2601                    !message || message[0] != ' ' ||
2602                    (message[1] != '+' && message[1] != '-') ||
2603                    !isdigit(message[2]) || !isdigit(message[3]) ||
2604                    !isdigit(message[4]) || !isdigit(message[5]))
2605                        continue; /* corrupt? */
2606                email_end[1] = '\0';
2607                tz = strtol(message + 1, NULL, 10);
2608                if (message[6] != '\t')
2609                        message += 6;
2610                else
2611                        message += 7;
2612                ret = fn(osha1, nsha1, sb.buf + 82, timestamp, tz, message,
2613                         cb_data);
2614                if (ret)
2615                        break;
2616        }
2617        fclose(logfp);
2618        strbuf_release(&sb);
2619        return ret;
2620}
2621
2622int for_each_reflog_ent(const char *refname, each_reflog_ent_fn fn, void *cb_data)
2623{
2624        return for_each_recent_reflog_ent(refname, fn, 0, cb_data);
2625}
2626
2627/*
2628 * Call fn for each reflog in the namespace indicated by name.  name
2629 * must be empty or end with '/'.  Name will be used as a scratch
2630 * space, but its contents will be restored before return.
2631 */
2632static int do_for_each_reflog(struct strbuf *name, each_ref_fn fn, void *cb_data)
2633{
2634        DIR *d = opendir(git_path("logs/%s", name->buf));
2635        int retval = 0;
2636        struct dirent *de;
2637        int oldlen = name->len;
2638
2639        if (!d)
2640                return name->len ? errno : 0;
2641
2642        while ((de = readdir(d)) != NULL) {
2643                struct stat st;
2644
2645                if (de->d_name[0] == '.')
2646                        continue;
2647                if (has_extension(de->d_name, ".lock"))
2648                        continue;
2649                strbuf_addstr(name, de->d_name);
2650                if (stat(git_path("logs/%s", name->buf), &st) < 0) {
2651                        ; /* silently ignore */
2652                } else {
2653                        if (S_ISDIR(st.st_mode)) {
2654                                strbuf_addch(name, '/');
2655                                retval = do_for_each_reflog(name, fn, cb_data);
2656                        } else {
2657                                unsigned char sha1[20];
2658                                if (read_ref_full(name->buf, sha1, 0, NULL))
2659                                        retval = error("bad ref for %s", name->buf);
2660                                else
2661                                        retval = fn(name->buf, sha1, 0, cb_data);
2662                        }
2663                        if (retval)
2664                                break;
2665                }
2666                strbuf_setlen(name, oldlen);
2667        }
2668        closedir(d);
2669        return retval;
2670}
2671
2672int for_each_reflog(each_ref_fn fn, void *cb_data)
2673{
2674        int retval;
2675        struct strbuf name;
2676        strbuf_init(&name, PATH_MAX);
2677        retval = do_for_each_reflog(&name, fn, cb_data);
2678        strbuf_release(&name);
2679        return retval;
2680}
2681
2682int update_ref(const char *action, const char *refname,
2683                const unsigned char *sha1, const unsigned char *oldval,
2684                int flags, enum action_on_err onerr)
2685{
2686        static struct ref_lock *lock;
2687        lock = lock_any_ref_for_update(refname, oldval, flags);
2688        if (!lock) {
2689                const char *str = "Cannot lock the ref '%s'.";
2690                switch (onerr) {
2691                case MSG_ON_ERR: error(str, refname); break;
2692                case DIE_ON_ERR: die(str, refname); break;
2693                case QUIET_ON_ERR: break;
2694                }
2695                return 1;
2696        }
2697        if (write_ref_sha1(lock, sha1, action) < 0) {
2698                const char *str = "Cannot update the ref '%s'.";
2699                switch (onerr) {
2700                case MSG_ON_ERR: error(str, refname); break;
2701                case DIE_ON_ERR: die(str, refname); break;
2702                case QUIET_ON_ERR: break;
2703                }
2704                return 1;
2705        }
2706        return 0;
2707}
2708
2709struct ref *find_ref_by_name(const struct ref *list, const char *name)
2710{
2711        for ( ; list; list = list->next)
2712                if (!strcmp(list->name, name))
2713                        return (struct ref *)list;
2714        return NULL;
2715}
2716
2717/*
2718 * generate a format suitable for scanf from a ref_rev_parse_rules
2719 * rule, that is replace the "%.*s" spec with a "%s" spec
2720 */
2721static void gen_scanf_fmt(char *scanf_fmt, const char *rule)
2722{
2723        char *spec;
2724
2725        spec = strstr(rule, "%.*s");
2726        if (!spec || strstr(spec + 4, "%.*s"))
2727                die("invalid rule in ref_rev_parse_rules: %s", rule);
2728
2729        /* copy all until spec */
2730        strncpy(scanf_fmt, rule, spec - rule);
2731        scanf_fmt[spec - rule] = '\0';
2732        /* copy new spec */
2733        strcat(scanf_fmt, "%s");
2734        /* copy remaining rule */
2735        strcat(scanf_fmt, spec + 4);
2736
2737        return;
2738}
2739
2740char *shorten_unambiguous_ref(const char *refname, int strict)
2741{
2742        int i;
2743        static char **scanf_fmts;
2744        static int nr_rules;
2745        char *short_name;
2746
2747        /* pre generate scanf formats from ref_rev_parse_rules[] */
2748        if (!nr_rules) {
2749                size_t total_len = 0;
2750
2751                /* the rule list is NULL terminated, count them first */
2752                for (; ref_rev_parse_rules[nr_rules]; nr_rules++)
2753                        /* no +1 because strlen("%s") < strlen("%.*s") */
2754                        total_len += strlen(ref_rev_parse_rules[nr_rules]);
2755
2756                scanf_fmts = xmalloc(nr_rules * sizeof(char *) + total_len);
2757
2758                total_len = 0;
2759                for (i = 0; i < nr_rules; i++) {
2760                        scanf_fmts[i] = (char *)&scanf_fmts[nr_rules]
2761                                        + total_len;
2762                        gen_scanf_fmt(scanf_fmts[i], ref_rev_parse_rules[i]);
2763                        total_len += strlen(ref_rev_parse_rules[i]);
2764                }
2765        }
2766
2767        /* bail out if there are no rules */
2768        if (!nr_rules)
2769                return xstrdup(refname);
2770
2771        /* buffer for scanf result, at most refname must fit */
2772        short_name = xstrdup(refname);
2773
2774        /* skip first rule, it will always match */
2775        for (i = nr_rules - 1; i > 0 ; --i) {
2776                int j;
2777                int rules_to_fail = i;
2778                int short_name_len;
2779
2780                if (1 != sscanf(refname, scanf_fmts[i], short_name))
2781                        continue;
2782
2783                short_name_len = strlen(short_name);
2784
2785                /*
2786                 * in strict mode, all (except the matched one) rules
2787                 * must fail to resolve to a valid non-ambiguous ref
2788                 */
2789                if (strict)
2790                        rules_to_fail = nr_rules;
2791
2792                /*
2793                 * check if the short name resolves to a valid ref,
2794                 * but use only rules prior to the matched one
2795                 */
2796                for (j = 0; j < rules_to_fail; j++) {
2797                        const char *rule = ref_rev_parse_rules[j];
2798                        char refname[PATH_MAX];
2799
2800                        /* skip matched rule */
2801                        if (i == j)
2802                                continue;
2803
2804                        /*
2805                         * the short name is ambiguous, if it resolves
2806                         * (with this previous rule) to a valid ref
2807                         * read_ref() returns 0 on success
2808                         */
2809                        mksnpath(refname, sizeof(refname),
2810                                 rule, short_name_len, short_name);
2811                        if (ref_exists(refname))
2812                                break;
2813                }
2814
2815                /*
2816                 * short name is non-ambiguous if all previous rules
2817                 * haven't resolved to a valid ref
2818                 */
2819                if (j == rules_to_fail)
2820                        return short_name;
2821        }
2822
2823        free(short_name);
2824        return xstrdup(refname);
2825}