refs.con commit Merge branch 'mh/attr-macro-doc' (ac35529)
   1#include "cache.h"
   2#include "refs.h"
   3#include "object.h"
   4#include "tag.h"
   5#include "dir.h"
   6#include "string-list.h"
   7
   8/*
   9 * Make sure "ref" is something reasonable to have under ".git/refs/";
  10 * We do not like it if:
  11 *
  12 * - any path component of it begins with ".", or
  13 * - it has double dots "..", or
  14 * - it has ASCII control character, "~", "^", ":" or SP, anywhere, or
  15 * - it ends with a "/".
  16 * - it ends with ".lock"
  17 * - it contains a "\" (backslash)
  18 */
  19
  20/* Return true iff ch is not allowed in reference names. */
  21static inline int bad_ref_char(int ch)
  22{
  23        if (((unsigned) ch) <= ' ' || ch == 0x7f ||
  24            ch == '~' || ch == '^' || ch == ':' || ch == '\\')
  25                return 1;
  26        /* 2.13 Pattern Matching Notation */
  27        if (ch == '*' || ch == '?' || ch == '[') /* Unsupported */
  28                return 1;
  29        return 0;
  30}
  31
  32/*
  33 * Try to read one refname component from the front of refname.  Return
  34 * the length of the component found, or -1 if the component is not
  35 * legal.
  36 */
  37static int check_refname_component(const char *refname, int flags)
  38{
  39        const char *cp;
  40        char last = '\0';
  41
  42        for (cp = refname; ; cp++) {
  43                char ch = *cp;
  44                if (ch == '\0' || ch == '/')
  45                        break;
  46                if (bad_ref_char(ch))
  47                        return -1; /* Illegal character in refname. */
  48                if (last == '.' && ch == '.')
  49                        return -1; /* Refname contains "..". */
  50                if (last == '@' && ch == '{')
  51                        return -1; /* Refname contains "@{". */
  52                last = ch;
  53        }
  54        if (cp == refname)
  55                return 0; /* Component has zero length. */
  56        if (refname[0] == '.') {
  57                if (!(flags & REFNAME_DOT_COMPONENT))
  58                        return -1; /* Component starts with '.'. */
  59                /*
  60                 * Even if leading dots are allowed, don't allow "."
  61                 * as a component (".." is prevented by a rule above).
  62                 */
  63                if (refname[1] == '\0')
  64                        return -1; /* Component equals ".". */
  65        }
  66        if (cp - refname >= 5 && !memcmp(cp - 5, ".lock", 5))
  67                return -1; /* Refname ends with ".lock". */
  68        return cp - refname;
  69}
  70
  71int check_refname_format(const char *refname, int flags)
  72{
  73        int component_len, component_count = 0;
  74
  75        if (!strcmp(refname, "@"))
  76                /* Refname is a single character '@'. */
  77                return -1;
  78
  79        while (1) {
  80                /* We are at the start of a path component. */
  81                component_len = check_refname_component(refname, flags);
  82                if (component_len <= 0) {
  83                        if ((flags & REFNAME_REFSPEC_PATTERN) &&
  84                                        refname[0] == '*' &&
  85                                        (refname[1] == '\0' || refname[1] == '/')) {
  86                                /* Accept one wildcard as a full refname component. */
  87                                flags &= ~REFNAME_REFSPEC_PATTERN;
  88                                component_len = 1;
  89                        } else {
  90                                return -1;
  91                        }
  92                }
  93                component_count++;
  94                if (refname[component_len] == '\0')
  95                        break;
  96                /* Skip to next component. */
  97                refname += component_len + 1;
  98        }
  99
 100        if (refname[component_len - 1] == '.')
 101                return -1; /* Refname ends with '.'. */
 102        if (!(flags & REFNAME_ALLOW_ONELEVEL) && component_count < 2)
 103                return -1; /* Refname has only one component. */
 104        return 0;
 105}
 106
 107struct ref_entry;
 108
 109/*
 110 * Information used (along with the information in ref_entry) to
 111 * describe a single cached reference.  This data structure only
 112 * occurs embedded in a union in struct ref_entry, and only when
 113 * (ref_entry->flag & REF_DIR) is zero.
 114 */
 115struct ref_value {
 116        /*
 117         * The name of the object to which this reference resolves
 118         * (which may be a tag object).  If REF_ISBROKEN, this is
 119         * null.  If REF_ISSYMREF, then this is the name of the object
 120         * referred to by the last reference in the symlink chain.
 121         */
 122        unsigned char sha1[20];
 123
 124        /*
 125         * If REF_KNOWS_PEELED, then this field holds the peeled value
 126         * of this reference, or null if the reference is known not to
 127         * be peelable.  See the documentation for peel_ref() for an
 128         * exact definition of "peelable".
 129         */
 130        unsigned char peeled[20];
 131};
 132
 133struct ref_cache;
 134
 135/*
 136 * Information used (along with the information in ref_entry) to
 137 * describe a level in the hierarchy of references.  This data
 138 * structure only occurs embedded in a union in struct ref_entry, and
 139 * only when (ref_entry.flag & REF_DIR) is set.  In that case,
 140 * (ref_entry.flag & REF_INCOMPLETE) determines whether the references
 141 * in the directory have already been read:
 142 *
 143 *     (ref_entry.flag & REF_INCOMPLETE) unset -- a directory of loose
 144 *         or packed references, already read.
 145 *
 146 *     (ref_entry.flag & REF_INCOMPLETE) set -- a directory of loose
 147 *         references that hasn't been read yet (nor has any of its
 148 *         subdirectories).
 149 *
 150 * Entries within a directory are stored within a growable array of
 151 * pointers to ref_entries (entries, nr, alloc).  Entries 0 <= i <
 152 * sorted are sorted by their component name in strcmp() order and the
 153 * remaining entries are unsorted.
 154 *
 155 * Loose references are read lazily, one directory at a time.  When a
 156 * directory of loose references is read, then all of the references
 157 * in that directory are stored, and REF_INCOMPLETE stubs are created
 158 * for any subdirectories, but the subdirectories themselves are not
 159 * read.  The reading is triggered by get_ref_dir().
 160 */
 161struct ref_dir {
 162        int nr, alloc;
 163
 164        /*
 165         * Entries with index 0 <= i < sorted are sorted by name.  New
 166         * entries are appended to the list unsorted, and are sorted
 167         * only when required; thus we avoid the need to sort the list
 168         * after the addition of every reference.
 169         */
 170        int sorted;
 171
 172        /* A pointer to the ref_cache that contains this ref_dir. */
 173        struct ref_cache *ref_cache;
 174
 175        struct ref_entry **entries;
 176};
 177
 178/*
 179 * Bit values for ref_entry::flag.  REF_ISSYMREF=0x01,
 180 * REF_ISPACKED=0x02, and REF_ISBROKEN=0x04 are public values; see
 181 * refs.h.
 182 */
 183
 184/*
 185 * The field ref_entry->u.value.peeled of this value entry contains
 186 * the correct peeled value for the reference, which might be
 187 * null_sha1 if the reference is not a tag or if it is broken.
 188 */
 189#define REF_KNOWS_PEELED 0x08
 190
 191/* ref_entry represents a directory of references */
 192#define REF_DIR 0x10
 193
 194/*
 195 * Entry has not yet been read from disk (used only for REF_DIR
 196 * entries representing loose references)
 197 */
 198#define REF_INCOMPLETE 0x20
 199
 200/*
 201 * A ref_entry represents either a reference or a "subdirectory" of
 202 * references.
 203 *
 204 * Each directory in the reference namespace is represented by a
 205 * ref_entry with (flags & REF_DIR) set and containing a subdir member
 206 * that holds the entries in that directory that have been read so
 207 * far.  If (flags & REF_INCOMPLETE) is set, then the directory and
 208 * its subdirectories haven't been read yet.  REF_INCOMPLETE is only
 209 * used for loose reference directories.
 210 *
 211 * References are represented by a ref_entry with (flags & REF_DIR)
 212 * unset and a value member that describes the reference's value.  The
 213 * flag member is at the ref_entry level, but it is also needed to
 214 * interpret the contents of the value field (in other words, a
 215 * ref_value object is not very much use without the enclosing
 216 * ref_entry).
 217 *
 218 * Reference names cannot end with slash and directories' names are
 219 * always stored with a trailing slash (except for the top-level
 220 * directory, which is always denoted by "").  This has two nice
 221 * consequences: (1) when the entries in each subdir are sorted
 222 * lexicographically by name (as they usually are), the references in
 223 * a whole tree can be generated in lexicographic order by traversing
 224 * the tree in left-to-right, depth-first order; (2) the names of
 225 * references and subdirectories cannot conflict, and therefore the
 226 * presence of an empty subdirectory does not block the creation of a
 227 * similarly-named reference.  (The fact that reference names with the
 228 * same leading components can conflict *with each other* is a
 229 * separate issue that is regulated by is_refname_available().)
 230 *
 231 * Please note that the name field contains the fully-qualified
 232 * reference (or subdirectory) name.  Space could be saved by only
 233 * storing the relative names.  But that would require the full names
 234 * to be generated on the fly when iterating in do_for_each_ref(), and
 235 * would break callback functions, who have always been able to assume
 236 * that the name strings that they are passed will not be freed during
 237 * the iteration.
 238 */
 239struct ref_entry {
 240        unsigned char flag; /* ISSYMREF? ISPACKED? */
 241        union {
 242                struct ref_value value; /* if not (flags&REF_DIR) */
 243                struct ref_dir subdir; /* if (flags&REF_DIR) */
 244        } u;
 245        /*
 246         * The full name of the reference (e.g., "refs/heads/master")
 247         * or the full name of the directory with a trailing slash
 248         * (e.g., "refs/heads/"):
 249         */
 250        char name[FLEX_ARRAY];
 251};
 252
 253static void read_loose_refs(const char *dirname, struct ref_dir *dir);
 254
 255static struct ref_dir *get_ref_dir(struct ref_entry *entry)
 256{
 257        struct ref_dir *dir;
 258        assert(entry->flag & REF_DIR);
 259        dir = &entry->u.subdir;
 260        if (entry->flag & REF_INCOMPLETE) {
 261                read_loose_refs(entry->name, dir);
 262                entry->flag &= ~REF_INCOMPLETE;
 263        }
 264        return dir;
 265}
 266
 267static struct ref_entry *create_ref_entry(const char *refname,
 268                                          const unsigned char *sha1, int flag,
 269                                          int check_name)
 270{
 271        int len;
 272        struct ref_entry *ref;
 273
 274        if (check_name &&
 275            check_refname_format(refname, REFNAME_ALLOW_ONELEVEL|REFNAME_DOT_COMPONENT))
 276                die("Reference has invalid format: '%s'", refname);
 277        len = strlen(refname) + 1;
 278        ref = xmalloc(sizeof(struct ref_entry) + len);
 279        hashcpy(ref->u.value.sha1, sha1);
 280        hashclr(ref->u.value.peeled);
 281        memcpy(ref->name, refname, len);
 282        ref->flag = flag;
 283        return ref;
 284}
 285
 286static void clear_ref_dir(struct ref_dir *dir);
 287
 288static void free_ref_entry(struct ref_entry *entry)
 289{
 290        if (entry->flag & REF_DIR) {
 291                /*
 292                 * Do not use get_ref_dir() here, as that might
 293                 * trigger the reading of loose refs.
 294                 */
 295                clear_ref_dir(&entry->u.subdir);
 296        }
 297        free(entry);
 298}
 299
 300/*
 301 * Add a ref_entry to the end of dir (unsorted).  Entry is always
 302 * stored directly in dir; no recursion into subdirectories is
 303 * done.
 304 */
 305static void add_entry_to_dir(struct ref_dir *dir, struct ref_entry *entry)
 306{
 307        ALLOC_GROW(dir->entries, dir->nr + 1, dir->alloc);
 308        dir->entries[dir->nr++] = entry;
 309        /* optimize for the case that entries are added in order */
 310        if (dir->nr == 1 ||
 311            (dir->nr == dir->sorted + 1 &&
 312             strcmp(dir->entries[dir->nr - 2]->name,
 313                    dir->entries[dir->nr - 1]->name) < 0))
 314                dir->sorted = dir->nr;
 315}
 316
 317/*
 318 * Clear and free all entries in dir, recursively.
 319 */
 320static void clear_ref_dir(struct ref_dir *dir)
 321{
 322        int i;
 323        for (i = 0; i < dir->nr; i++)
 324                free_ref_entry(dir->entries[i]);
 325        free(dir->entries);
 326        dir->sorted = dir->nr = dir->alloc = 0;
 327        dir->entries = NULL;
 328}
 329
 330/*
 331 * Create a struct ref_entry object for the specified dirname.
 332 * dirname is the name of the directory with a trailing slash (e.g.,
 333 * "refs/heads/") or "" for the top-level directory.
 334 */
 335static struct ref_entry *create_dir_entry(struct ref_cache *ref_cache,
 336                                          const char *dirname, size_t len,
 337                                          int incomplete)
 338{
 339        struct ref_entry *direntry;
 340        direntry = xcalloc(1, sizeof(struct ref_entry) + len + 1);
 341        memcpy(direntry->name, dirname, len);
 342        direntry->name[len] = '\0';
 343        direntry->u.subdir.ref_cache = ref_cache;
 344        direntry->flag = REF_DIR | (incomplete ? REF_INCOMPLETE : 0);
 345        return direntry;
 346}
 347
 348static int ref_entry_cmp(const void *a, const void *b)
 349{
 350        struct ref_entry *one = *(struct ref_entry **)a;
 351        struct ref_entry *two = *(struct ref_entry **)b;
 352        return strcmp(one->name, two->name);
 353}
 354
 355static void sort_ref_dir(struct ref_dir *dir);
 356
 357struct string_slice {
 358        size_t len;
 359        const char *str;
 360};
 361
 362static int ref_entry_cmp_sslice(const void *key_, const void *ent_)
 363{
 364        const struct string_slice *key = key_;
 365        const struct ref_entry *ent = *(const struct ref_entry * const *)ent_;
 366        int cmp = strncmp(key->str, ent->name, key->len);
 367        if (cmp)
 368                return cmp;
 369        return '\0' - (unsigned char)ent->name[key->len];
 370}
 371
 372/*
 373 * Return the index of the entry with the given refname from the
 374 * ref_dir (non-recursively), sorting dir if necessary.  Return -1 if
 375 * no such entry is found.  dir must already be complete.
 376 */
 377static int search_ref_dir(struct ref_dir *dir, const char *refname, size_t len)
 378{
 379        struct ref_entry **r;
 380        struct string_slice key;
 381
 382        if (refname == NULL || !dir->nr)
 383                return -1;
 384
 385        sort_ref_dir(dir);
 386        key.len = len;
 387        key.str = refname;
 388        r = bsearch(&key, dir->entries, dir->nr, sizeof(*dir->entries),
 389                    ref_entry_cmp_sslice);
 390
 391        if (r == NULL)
 392                return -1;
 393
 394        return r - dir->entries;
 395}
 396
 397/*
 398 * Search for a directory entry directly within dir (without
 399 * recursing).  Sort dir if necessary.  subdirname must be a directory
 400 * name (i.e., end in '/').  If mkdir is set, then create the
 401 * directory if it is missing; otherwise, return NULL if the desired
 402 * directory cannot be found.  dir must already be complete.
 403 */
 404static struct ref_dir *search_for_subdir(struct ref_dir *dir,
 405                                         const char *subdirname, size_t len,
 406                                         int mkdir)
 407{
 408        int entry_index = search_ref_dir(dir, subdirname, len);
 409        struct ref_entry *entry;
 410        if (entry_index == -1) {
 411                if (!mkdir)
 412                        return NULL;
 413                /*
 414                 * Since dir is complete, the absence of a subdir
 415                 * means that the subdir really doesn't exist;
 416                 * therefore, create an empty record for it but mark
 417                 * the record complete.
 418                 */
 419                entry = create_dir_entry(dir->ref_cache, subdirname, len, 0);
 420                add_entry_to_dir(dir, entry);
 421        } else {
 422                entry = dir->entries[entry_index];
 423        }
 424        return get_ref_dir(entry);
 425}
 426
 427/*
 428 * If refname is a reference name, find the ref_dir within the dir
 429 * tree that should hold refname.  If refname is a directory name
 430 * (i.e., ends in '/'), then return that ref_dir itself.  dir must
 431 * represent the top-level directory and must already be complete.
 432 * Sort ref_dirs and recurse into subdirectories as necessary.  If
 433 * mkdir is set, then create any missing directories; otherwise,
 434 * return NULL if the desired directory cannot be found.
 435 */
 436static struct ref_dir *find_containing_dir(struct ref_dir *dir,
 437                                           const char *refname, int mkdir)
 438{
 439        const char *slash;
 440        for (slash = strchr(refname, '/'); slash; slash = strchr(slash + 1, '/')) {
 441                size_t dirnamelen = slash - refname + 1;
 442                struct ref_dir *subdir;
 443                subdir = search_for_subdir(dir, refname, dirnamelen, mkdir);
 444                if (!subdir) {
 445                        dir = NULL;
 446                        break;
 447                }
 448                dir = subdir;
 449        }
 450
 451        return dir;
 452}
 453
 454/*
 455 * Find the value entry with the given name in dir, sorting ref_dirs
 456 * and recursing into subdirectories as necessary.  If the name is not
 457 * found or it corresponds to a directory entry, return NULL.
 458 */
 459static struct ref_entry *find_ref(struct ref_dir *dir, const char *refname)
 460{
 461        int entry_index;
 462        struct ref_entry *entry;
 463        dir = find_containing_dir(dir, refname, 0);
 464        if (!dir)
 465                return NULL;
 466        entry_index = search_ref_dir(dir, refname, strlen(refname));
 467        if (entry_index == -1)
 468                return NULL;
 469        entry = dir->entries[entry_index];
 470        return (entry->flag & REF_DIR) ? NULL : entry;
 471}
 472
 473/*
 474 * Remove the entry with the given name from dir, recursing into
 475 * subdirectories as necessary.  If refname is the name of a directory
 476 * (i.e., ends with '/'), then remove the directory and its contents.
 477 * If the removal was successful, return the number of entries
 478 * remaining in the directory entry that contained the deleted entry.
 479 * If the name was not found, return -1.  Please note that this
 480 * function only deletes the entry from the cache; it does not delete
 481 * it from the filesystem or ensure that other cache entries (which
 482 * might be symbolic references to the removed entry) are updated.
 483 * Nor does it remove any containing dir entries that might be made
 484 * empty by the removal.  dir must represent the top-level directory
 485 * and must already be complete.
 486 */
 487static int remove_entry(struct ref_dir *dir, const char *refname)
 488{
 489        int refname_len = strlen(refname);
 490        int entry_index;
 491        struct ref_entry *entry;
 492        int is_dir = refname[refname_len - 1] == '/';
 493        if (is_dir) {
 494                /*
 495                 * refname represents a reference directory.  Remove
 496                 * the trailing slash; otherwise we will get the
 497                 * directory *representing* refname rather than the
 498                 * one *containing* it.
 499                 */
 500                char *dirname = xmemdupz(refname, refname_len - 1);
 501                dir = find_containing_dir(dir, dirname, 0);
 502                free(dirname);
 503        } else {
 504                dir = find_containing_dir(dir, refname, 0);
 505        }
 506        if (!dir)
 507                return -1;
 508        entry_index = search_ref_dir(dir, refname, refname_len);
 509        if (entry_index == -1)
 510                return -1;
 511        entry = dir->entries[entry_index];
 512
 513        memmove(&dir->entries[entry_index],
 514                &dir->entries[entry_index + 1],
 515                (dir->nr - entry_index - 1) * sizeof(*dir->entries)
 516                );
 517        dir->nr--;
 518        if (dir->sorted > entry_index)
 519                dir->sorted--;
 520        free_ref_entry(entry);
 521        return dir->nr;
 522}
 523
 524/*
 525 * Add a ref_entry to the ref_dir (unsorted), recursing into
 526 * subdirectories as necessary.  dir must represent the top-level
 527 * directory.  Return 0 on success.
 528 */
 529static int add_ref(struct ref_dir *dir, struct ref_entry *ref)
 530{
 531        dir = find_containing_dir(dir, ref->name, 1);
 532        if (!dir)
 533                return -1;
 534        add_entry_to_dir(dir, ref);
 535        return 0;
 536}
 537
 538/*
 539 * Emit a warning and return true iff ref1 and ref2 have the same name
 540 * and the same sha1.  Die if they have the same name but different
 541 * sha1s.
 542 */
 543static int is_dup_ref(const struct ref_entry *ref1, const struct ref_entry *ref2)
 544{
 545        if (strcmp(ref1->name, ref2->name))
 546                return 0;
 547
 548        /* Duplicate name; make sure that they don't conflict: */
 549
 550        if ((ref1->flag & REF_DIR) || (ref2->flag & REF_DIR))
 551                /* This is impossible by construction */
 552                die("Reference directory conflict: %s", ref1->name);
 553
 554        if (hashcmp(ref1->u.value.sha1, ref2->u.value.sha1))
 555                die("Duplicated ref, and SHA1s don't match: %s", ref1->name);
 556
 557        warning("Duplicated ref: %s", ref1->name);
 558        return 1;
 559}
 560
 561/*
 562 * Sort the entries in dir non-recursively (if they are not already
 563 * sorted) and remove any duplicate entries.
 564 */
 565static void sort_ref_dir(struct ref_dir *dir)
 566{
 567        int i, j;
 568        struct ref_entry *last = NULL;
 569
 570        /*
 571         * This check also prevents passing a zero-length array to qsort(),
 572         * which is a problem on some platforms.
 573         */
 574        if (dir->sorted == dir->nr)
 575                return;
 576
 577        qsort(dir->entries, dir->nr, sizeof(*dir->entries), ref_entry_cmp);
 578
 579        /* Remove any duplicates: */
 580        for (i = 0, j = 0; j < dir->nr; j++) {
 581                struct ref_entry *entry = dir->entries[j];
 582                if (last && is_dup_ref(last, entry))
 583                        free_ref_entry(entry);
 584                else
 585                        last = dir->entries[i++] = entry;
 586        }
 587        dir->sorted = dir->nr = i;
 588}
 589
 590/* Include broken references in a do_for_each_ref*() iteration: */
 591#define DO_FOR_EACH_INCLUDE_BROKEN 0x01
 592
 593/*
 594 * Return true iff the reference described by entry can be resolved to
 595 * an object in the database.  Emit a warning if the referred-to
 596 * object does not exist.
 597 */
 598static int ref_resolves_to_object(struct ref_entry *entry)
 599{
 600        if (entry->flag & REF_ISBROKEN)
 601                return 0;
 602        if (!has_sha1_file(entry->u.value.sha1)) {
 603                error("%s does not point to a valid object!", entry->name);
 604                return 0;
 605        }
 606        return 1;
 607}
 608
 609/*
 610 * current_ref is a performance hack: when iterating over references
 611 * using the for_each_ref*() functions, current_ref is set to the
 612 * current reference's entry before calling the callback function.  If
 613 * the callback function calls peel_ref(), then peel_ref() first
 614 * checks whether the reference to be peeled is the current reference
 615 * (it usually is) and if so, returns that reference's peeled version
 616 * if it is available.  This avoids a refname lookup in a common case.
 617 */
 618static struct ref_entry *current_ref;
 619
 620typedef int each_ref_entry_fn(struct ref_entry *entry, void *cb_data);
 621
 622struct ref_entry_cb {
 623        const char *base;
 624        int trim;
 625        int flags;
 626        each_ref_fn *fn;
 627        void *cb_data;
 628};
 629
 630/*
 631 * Handle one reference in a do_for_each_ref*()-style iteration,
 632 * calling an each_ref_fn for each entry.
 633 */
 634static int do_one_ref(struct ref_entry *entry, void *cb_data)
 635{
 636        struct ref_entry_cb *data = cb_data;
 637        struct ref_entry *old_current_ref;
 638        int retval;
 639
 640        if (!starts_with(entry->name, data->base))
 641                return 0;
 642
 643        if (!(data->flags & DO_FOR_EACH_INCLUDE_BROKEN) &&
 644              !ref_resolves_to_object(entry))
 645                return 0;
 646
 647        /* Store the old value, in case this is a recursive call: */
 648        old_current_ref = current_ref;
 649        current_ref = entry;
 650        retval = data->fn(entry->name + data->trim, entry->u.value.sha1,
 651                          entry->flag, data->cb_data);
 652        current_ref = old_current_ref;
 653        return retval;
 654}
 655
 656/*
 657 * Call fn for each reference in dir that has index in the range
 658 * offset <= index < dir->nr.  Recurse into subdirectories that are in
 659 * that index range, sorting them before iterating.  This function
 660 * does not sort dir itself; it should be sorted beforehand.  fn is
 661 * called for all references, including broken ones.
 662 */
 663static int do_for_each_entry_in_dir(struct ref_dir *dir, int offset,
 664                                    each_ref_entry_fn fn, void *cb_data)
 665{
 666        int i;
 667        assert(dir->sorted == dir->nr);
 668        for (i = offset; i < dir->nr; i++) {
 669                struct ref_entry *entry = dir->entries[i];
 670                int retval;
 671                if (entry->flag & REF_DIR) {
 672                        struct ref_dir *subdir = get_ref_dir(entry);
 673                        sort_ref_dir(subdir);
 674                        retval = do_for_each_entry_in_dir(subdir, 0, fn, cb_data);
 675                } else {
 676                        retval = fn(entry, cb_data);
 677                }
 678                if (retval)
 679                        return retval;
 680        }
 681        return 0;
 682}
 683
 684/*
 685 * Call fn for each reference in the union of dir1 and dir2, in order
 686 * by refname.  Recurse into subdirectories.  If a value entry appears
 687 * in both dir1 and dir2, then only process the version that is in
 688 * dir2.  The input dirs must already be sorted, but subdirs will be
 689 * sorted as needed.  fn is called for all references, including
 690 * broken ones.
 691 */
 692static int do_for_each_entry_in_dirs(struct ref_dir *dir1,
 693                                     struct ref_dir *dir2,
 694                                     each_ref_entry_fn fn, void *cb_data)
 695{
 696        int retval;
 697        int i1 = 0, i2 = 0;
 698
 699        assert(dir1->sorted == dir1->nr);
 700        assert(dir2->sorted == dir2->nr);
 701        while (1) {
 702                struct ref_entry *e1, *e2;
 703                int cmp;
 704                if (i1 == dir1->nr) {
 705                        return do_for_each_entry_in_dir(dir2, i2, fn, cb_data);
 706                }
 707                if (i2 == dir2->nr) {
 708                        return do_for_each_entry_in_dir(dir1, i1, fn, cb_data);
 709                }
 710                e1 = dir1->entries[i1];
 711                e2 = dir2->entries[i2];
 712                cmp = strcmp(e1->name, e2->name);
 713                if (cmp == 0) {
 714                        if ((e1->flag & REF_DIR) && (e2->flag & REF_DIR)) {
 715                                /* Both are directories; descend them in parallel. */
 716                                struct ref_dir *subdir1 = get_ref_dir(e1);
 717                                struct ref_dir *subdir2 = get_ref_dir(e2);
 718                                sort_ref_dir(subdir1);
 719                                sort_ref_dir(subdir2);
 720                                retval = do_for_each_entry_in_dirs(
 721                                                subdir1, subdir2, fn, cb_data);
 722                                i1++;
 723                                i2++;
 724                        } else if (!(e1->flag & REF_DIR) && !(e2->flag & REF_DIR)) {
 725                                /* Both are references; ignore the one from dir1. */
 726                                retval = fn(e2, cb_data);
 727                                i1++;
 728                                i2++;
 729                        } else {
 730                                die("conflict between reference and directory: %s",
 731                                    e1->name);
 732                        }
 733                } else {
 734                        struct ref_entry *e;
 735                        if (cmp < 0) {
 736                                e = e1;
 737                                i1++;
 738                        } else {
 739                                e = e2;
 740                                i2++;
 741                        }
 742                        if (e->flag & REF_DIR) {
 743                                struct ref_dir *subdir = get_ref_dir(e);
 744                                sort_ref_dir(subdir);
 745                                retval = do_for_each_entry_in_dir(
 746                                                subdir, 0, fn, cb_data);
 747                        } else {
 748                                retval = fn(e, cb_data);
 749                        }
 750                }
 751                if (retval)
 752                        return retval;
 753        }
 754}
 755
 756/*
 757 * Load all of the refs from the dir into our in-memory cache. The hard work
 758 * of loading loose refs is done by get_ref_dir(), so we just need to recurse
 759 * through all of the sub-directories. We do not even need to care about
 760 * sorting, as traversal order does not matter to us.
 761 */
 762static void prime_ref_dir(struct ref_dir *dir)
 763{
 764        int i;
 765        for (i = 0; i < dir->nr; i++) {
 766                struct ref_entry *entry = dir->entries[i];
 767                if (entry->flag & REF_DIR)
 768                        prime_ref_dir(get_ref_dir(entry));
 769        }
 770}
 771/*
 772 * Return true iff refname1 and refname2 conflict with each other.
 773 * Two reference names conflict if one of them exactly matches the
 774 * leading components of the other; e.g., "foo/bar" conflicts with
 775 * both "foo" and with "foo/bar/baz" but not with "foo/bar" or
 776 * "foo/barbados".
 777 */
 778static int names_conflict(const char *refname1, const char *refname2)
 779{
 780        for (; *refname1 && *refname1 == *refname2; refname1++, refname2++)
 781                ;
 782        return (*refname1 == '\0' && *refname2 == '/')
 783                || (*refname1 == '/' && *refname2 == '\0');
 784}
 785
 786struct name_conflict_cb {
 787        const char *refname;
 788        const char *oldrefname;
 789        const char *conflicting_refname;
 790};
 791
 792static int name_conflict_fn(struct ref_entry *entry, void *cb_data)
 793{
 794        struct name_conflict_cb *data = (struct name_conflict_cb *)cb_data;
 795        if (data->oldrefname && !strcmp(data->oldrefname, entry->name))
 796                return 0;
 797        if (names_conflict(data->refname, entry->name)) {
 798                data->conflicting_refname = entry->name;
 799                return 1;
 800        }
 801        return 0;
 802}
 803
 804/*
 805 * Return true iff a reference named refname could be created without
 806 * conflicting with the name of an existing reference in dir.  If
 807 * oldrefname is non-NULL, ignore potential conflicts with oldrefname
 808 * (e.g., because oldrefname is scheduled for deletion in the same
 809 * operation).
 810 */
 811static int is_refname_available(const char *refname, const char *oldrefname,
 812                                struct ref_dir *dir)
 813{
 814        struct name_conflict_cb data;
 815        data.refname = refname;
 816        data.oldrefname = oldrefname;
 817        data.conflicting_refname = NULL;
 818
 819        sort_ref_dir(dir);
 820        if (do_for_each_entry_in_dir(dir, 0, name_conflict_fn, &data)) {
 821                error("'%s' exists; cannot create '%s'",
 822                      data.conflicting_refname, refname);
 823                return 0;
 824        }
 825        return 1;
 826}
 827
 828struct packed_ref_cache {
 829        struct ref_entry *root;
 830
 831        /*
 832         * Count of references to the data structure in this instance,
 833         * including the pointer from ref_cache::packed if any.  The
 834         * data will not be freed as long as the reference count is
 835         * nonzero.
 836         */
 837        unsigned int referrers;
 838
 839        /*
 840         * Iff the packed-refs file associated with this instance is
 841         * currently locked for writing, this points at the associated
 842         * lock (which is owned by somebody else).  The referrer count
 843         * is also incremented when the file is locked and decremented
 844         * when it is unlocked.
 845         */
 846        struct lock_file *lock;
 847
 848        /* The metadata from when this packed-refs cache was read */
 849        struct stat_validity validity;
 850};
 851
 852/*
 853 * Future: need to be in "struct repository"
 854 * when doing a full libification.
 855 */
 856static struct ref_cache {
 857        struct ref_cache *next;
 858        struct ref_entry *loose;
 859        struct packed_ref_cache *packed;
 860        /*
 861         * The submodule name, or "" for the main repo.  We allocate
 862         * length 1 rather than FLEX_ARRAY so that the main ref_cache
 863         * is initialized correctly.
 864         */
 865        char name[1];
 866} ref_cache, *submodule_ref_caches;
 867
 868/* Lock used for the main packed-refs file: */
 869static struct lock_file packlock;
 870
 871/*
 872 * Increment the reference count of *packed_refs.
 873 */
 874static void acquire_packed_ref_cache(struct packed_ref_cache *packed_refs)
 875{
 876        packed_refs->referrers++;
 877}
 878
 879/*
 880 * Decrease the reference count of *packed_refs.  If it goes to zero,
 881 * free *packed_refs and return true; otherwise return false.
 882 */
 883static int release_packed_ref_cache(struct packed_ref_cache *packed_refs)
 884{
 885        if (!--packed_refs->referrers) {
 886                free_ref_entry(packed_refs->root);
 887                stat_validity_clear(&packed_refs->validity);
 888                free(packed_refs);
 889                return 1;
 890        } else {
 891                return 0;
 892        }
 893}
 894
 895static void clear_packed_ref_cache(struct ref_cache *refs)
 896{
 897        if (refs->packed) {
 898                struct packed_ref_cache *packed_refs = refs->packed;
 899
 900                if (packed_refs->lock)
 901                        die("internal error: packed-ref cache cleared while locked");
 902                refs->packed = NULL;
 903                release_packed_ref_cache(packed_refs);
 904        }
 905}
 906
 907static void clear_loose_ref_cache(struct ref_cache *refs)
 908{
 909        if (refs->loose) {
 910                free_ref_entry(refs->loose);
 911                refs->loose = NULL;
 912        }
 913}
 914
 915static struct ref_cache *create_ref_cache(const char *submodule)
 916{
 917        int len;
 918        struct ref_cache *refs;
 919        if (!submodule)
 920                submodule = "";
 921        len = strlen(submodule) + 1;
 922        refs = xcalloc(1, sizeof(struct ref_cache) + len);
 923        memcpy(refs->name, submodule, len);
 924        return refs;
 925}
 926
 927/*
 928 * Return a pointer to a ref_cache for the specified submodule. For
 929 * the main repository, use submodule==NULL. The returned structure
 930 * will be allocated and initialized but not necessarily populated; it
 931 * should not be freed.
 932 */
 933static struct ref_cache *get_ref_cache(const char *submodule)
 934{
 935        struct ref_cache *refs;
 936
 937        if (!submodule || !*submodule)
 938                return &ref_cache;
 939
 940        for (refs = submodule_ref_caches; refs; refs = refs->next)
 941                if (!strcmp(submodule, refs->name))
 942                        return refs;
 943
 944        refs = create_ref_cache(submodule);
 945        refs->next = submodule_ref_caches;
 946        submodule_ref_caches = refs;
 947        return refs;
 948}
 949
 950/* The length of a peeled reference line in packed-refs, including EOL: */
 951#define PEELED_LINE_LENGTH 42
 952
 953/*
 954 * The packed-refs header line that we write out.  Perhaps other
 955 * traits will be added later.  The trailing space is required.
 956 */
 957static const char PACKED_REFS_HEADER[] =
 958        "# pack-refs with: peeled fully-peeled \n";
 959
 960/*
 961 * Parse one line from a packed-refs file.  Write the SHA1 to sha1.
 962 * Return a pointer to the refname within the line (null-terminated),
 963 * or NULL if there was a problem.
 964 */
 965static const char *parse_ref_line(char *line, unsigned char *sha1)
 966{
 967        /*
 968         * 42: the answer to everything.
 969         *
 970         * In this case, it happens to be the answer to
 971         *  40 (length of sha1 hex representation)
 972         *  +1 (space in between hex and name)
 973         *  +1 (newline at the end of the line)
 974         */
 975        int len = strlen(line) - 42;
 976
 977        if (len <= 0)
 978                return NULL;
 979        if (get_sha1_hex(line, sha1) < 0)
 980                return NULL;
 981        if (!isspace(line[40]))
 982                return NULL;
 983        line += 41;
 984        if (isspace(*line))
 985                return NULL;
 986        if (line[len] != '\n')
 987                return NULL;
 988        line[len] = 0;
 989
 990        return line;
 991}
 992
 993/*
 994 * Read f, which is a packed-refs file, into dir.
 995 *
 996 * A comment line of the form "# pack-refs with: " may contain zero or
 997 * more traits. We interpret the traits as follows:
 998 *
 999 *   No traits:
1000 *
1001 *      Probably no references are peeled. But if the file contains a
1002 *      peeled value for a reference, we will use it.
1003 *
1004 *   peeled:
1005 *
1006 *      References under "refs/tags/", if they *can* be peeled, *are*
1007 *      peeled in this file. References outside of "refs/tags/" are
1008 *      probably not peeled even if they could have been, but if we find
1009 *      a peeled value for such a reference we will use it.
1010 *
1011 *   fully-peeled:
1012 *
1013 *      All references in the file that can be peeled are peeled.
1014 *      Inversely (and this is more important), any references in the
1015 *      file for which no peeled value is recorded is not peelable. This
1016 *      trait should typically be written alongside "peeled" for
1017 *      compatibility with older clients, but we do not require it
1018 *      (i.e., "peeled" is a no-op if "fully-peeled" is set).
1019 */
1020static void read_packed_refs(FILE *f, struct ref_dir *dir)
1021{
1022        struct ref_entry *last = NULL;
1023        char refline[PATH_MAX];
1024        enum { PEELED_NONE, PEELED_TAGS, PEELED_FULLY } peeled = PEELED_NONE;
1025
1026        while (fgets(refline, sizeof(refline), f)) {
1027                unsigned char sha1[20];
1028                const char *refname;
1029                static const char header[] = "# pack-refs with:";
1030
1031                if (!strncmp(refline, header, sizeof(header)-1)) {
1032                        const char *traits = refline + sizeof(header) - 1;
1033                        if (strstr(traits, " fully-peeled "))
1034                                peeled = PEELED_FULLY;
1035                        else if (strstr(traits, " peeled "))
1036                                peeled = PEELED_TAGS;
1037                        /* perhaps other traits later as well */
1038                        continue;
1039                }
1040
1041                refname = parse_ref_line(refline, sha1);
1042                if (refname) {
1043                        last = create_ref_entry(refname, sha1, REF_ISPACKED, 1);
1044                        if (peeled == PEELED_FULLY ||
1045                            (peeled == PEELED_TAGS && starts_with(refname, "refs/tags/")))
1046                                last->flag |= REF_KNOWS_PEELED;
1047                        add_ref(dir, last);
1048                        continue;
1049                }
1050                if (last &&
1051                    refline[0] == '^' &&
1052                    strlen(refline) == PEELED_LINE_LENGTH &&
1053                    refline[PEELED_LINE_LENGTH - 1] == '\n' &&
1054                    !get_sha1_hex(refline + 1, sha1)) {
1055                        hashcpy(last->u.value.peeled, sha1);
1056                        /*
1057                         * Regardless of what the file header said,
1058                         * we definitely know the value of *this*
1059                         * reference:
1060                         */
1061                        last->flag |= REF_KNOWS_PEELED;
1062                }
1063        }
1064}
1065
1066/*
1067 * Get the packed_ref_cache for the specified ref_cache, creating it
1068 * if necessary.
1069 */
1070static struct packed_ref_cache *get_packed_ref_cache(struct ref_cache *refs)
1071{
1072        const char *packed_refs_file;
1073
1074        if (*refs->name)
1075                packed_refs_file = git_path_submodule(refs->name, "packed-refs");
1076        else
1077                packed_refs_file = git_path("packed-refs");
1078
1079        if (refs->packed &&
1080            !stat_validity_check(&refs->packed->validity, packed_refs_file))
1081                clear_packed_ref_cache(refs);
1082
1083        if (!refs->packed) {
1084                FILE *f;
1085
1086                refs->packed = xcalloc(1, sizeof(*refs->packed));
1087                acquire_packed_ref_cache(refs->packed);
1088                refs->packed->root = create_dir_entry(refs, "", 0, 0);
1089                f = fopen(packed_refs_file, "r");
1090                if (f) {
1091                        stat_validity_update(&refs->packed->validity, fileno(f));
1092                        read_packed_refs(f, get_ref_dir(refs->packed->root));
1093                        fclose(f);
1094                }
1095        }
1096        return refs->packed;
1097}
1098
1099static struct ref_dir *get_packed_ref_dir(struct packed_ref_cache *packed_ref_cache)
1100{
1101        return get_ref_dir(packed_ref_cache->root);
1102}
1103
1104static struct ref_dir *get_packed_refs(struct ref_cache *refs)
1105{
1106        return get_packed_ref_dir(get_packed_ref_cache(refs));
1107}
1108
1109void add_packed_ref(const char *refname, const unsigned char *sha1)
1110{
1111        struct packed_ref_cache *packed_ref_cache =
1112                get_packed_ref_cache(&ref_cache);
1113
1114        if (!packed_ref_cache->lock)
1115                die("internal error: packed refs not locked");
1116        add_ref(get_packed_ref_dir(packed_ref_cache),
1117                create_ref_entry(refname, sha1, REF_ISPACKED, 1));
1118}
1119
1120/*
1121 * Read the loose references from the namespace dirname into dir
1122 * (without recursing).  dirname must end with '/'.  dir must be the
1123 * directory entry corresponding to dirname.
1124 */
1125static void read_loose_refs(const char *dirname, struct ref_dir *dir)
1126{
1127        struct ref_cache *refs = dir->ref_cache;
1128        DIR *d;
1129        const char *path;
1130        struct dirent *de;
1131        int dirnamelen = strlen(dirname);
1132        struct strbuf refname;
1133
1134        if (*refs->name)
1135                path = git_path_submodule(refs->name, "%s", dirname);
1136        else
1137                path = git_path("%s", dirname);
1138
1139        d = opendir(path);
1140        if (!d)
1141                return;
1142
1143        strbuf_init(&refname, dirnamelen + 257);
1144        strbuf_add(&refname, dirname, dirnamelen);
1145
1146        while ((de = readdir(d)) != NULL) {
1147                unsigned char sha1[20];
1148                struct stat st;
1149                int flag;
1150                const char *refdir;
1151
1152                if (de->d_name[0] == '.')
1153                        continue;
1154                if (has_extension(de->d_name, ".lock"))
1155                        continue;
1156                strbuf_addstr(&refname, de->d_name);
1157                refdir = *refs->name
1158                        ? git_path_submodule(refs->name, "%s", refname.buf)
1159                        : git_path("%s", refname.buf);
1160                if (stat(refdir, &st) < 0) {
1161                        ; /* silently ignore */
1162                } else if (S_ISDIR(st.st_mode)) {
1163                        strbuf_addch(&refname, '/');
1164                        add_entry_to_dir(dir,
1165                                         create_dir_entry(refs, refname.buf,
1166                                                          refname.len, 1));
1167                } else {
1168                        if (*refs->name) {
1169                                hashclr(sha1);
1170                                flag = 0;
1171                                if (resolve_gitlink_ref(refs->name, refname.buf, sha1) < 0) {
1172                                        hashclr(sha1);
1173                                        flag |= REF_ISBROKEN;
1174                                }
1175                        } else if (read_ref_full(refname.buf, sha1, 1, &flag)) {
1176                                hashclr(sha1);
1177                                flag |= REF_ISBROKEN;
1178                        }
1179                        add_entry_to_dir(dir,
1180                                         create_ref_entry(refname.buf, sha1, flag, 1));
1181                }
1182                strbuf_setlen(&refname, dirnamelen);
1183        }
1184        strbuf_release(&refname);
1185        closedir(d);
1186}
1187
1188static struct ref_dir *get_loose_refs(struct ref_cache *refs)
1189{
1190        if (!refs->loose) {
1191                /*
1192                 * Mark the top-level directory complete because we
1193                 * are about to read the only subdirectory that can
1194                 * hold references:
1195                 */
1196                refs->loose = create_dir_entry(refs, "", 0, 0);
1197                /*
1198                 * Create an incomplete entry for "refs/":
1199                 */
1200                add_entry_to_dir(get_ref_dir(refs->loose),
1201                                 create_dir_entry(refs, "refs/", 5, 1));
1202        }
1203        return get_ref_dir(refs->loose);
1204}
1205
1206/* We allow "recursive" symbolic refs. Only within reason, though */
1207#define MAXDEPTH 5
1208#define MAXREFLEN (1024)
1209
1210/*
1211 * Called by resolve_gitlink_ref_recursive() after it failed to read
1212 * from the loose refs in ref_cache refs. Find <refname> in the
1213 * packed-refs file for the submodule.
1214 */
1215static int resolve_gitlink_packed_ref(struct ref_cache *refs,
1216                                      const char *refname, unsigned char *sha1)
1217{
1218        struct ref_entry *ref;
1219        struct ref_dir *dir = get_packed_refs(refs);
1220
1221        ref = find_ref(dir, refname);
1222        if (ref == NULL)
1223                return -1;
1224
1225        memcpy(sha1, ref->u.value.sha1, 20);
1226        return 0;
1227}
1228
1229static int resolve_gitlink_ref_recursive(struct ref_cache *refs,
1230                                         const char *refname, unsigned char *sha1,
1231                                         int recursion)
1232{
1233        int fd, len;
1234        char buffer[128], *p;
1235        char *path;
1236
1237        if (recursion > MAXDEPTH || strlen(refname) > MAXREFLEN)
1238                return -1;
1239        path = *refs->name
1240                ? git_path_submodule(refs->name, "%s", refname)
1241                : git_path("%s", refname);
1242        fd = open(path, O_RDONLY);
1243        if (fd < 0)
1244                return resolve_gitlink_packed_ref(refs, refname, sha1);
1245
1246        len = read(fd, buffer, sizeof(buffer)-1);
1247        close(fd);
1248        if (len < 0)
1249                return -1;
1250        while (len && isspace(buffer[len-1]))
1251                len--;
1252        buffer[len] = 0;
1253
1254        /* Was it a detached head or an old-fashioned symlink? */
1255        if (!get_sha1_hex(buffer, sha1))
1256                return 0;
1257
1258        /* Symref? */
1259        if (strncmp(buffer, "ref:", 4))
1260                return -1;
1261        p = buffer + 4;
1262        while (isspace(*p))
1263                p++;
1264
1265        return resolve_gitlink_ref_recursive(refs, p, sha1, recursion+1);
1266}
1267
1268int resolve_gitlink_ref(const char *path, const char *refname, unsigned char *sha1)
1269{
1270        int len = strlen(path), retval;
1271        char *submodule;
1272        struct ref_cache *refs;
1273
1274        while (len && path[len-1] == '/')
1275                len--;
1276        if (!len)
1277                return -1;
1278        submodule = xstrndup(path, len);
1279        refs = get_ref_cache(submodule);
1280        free(submodule);
1281
1282        retval = resolve_gitlink_ref_recursive(refs, refname, sha1, 0);
1283        return retval;
1284}
1285
1286/*
1287 * Return the ref_entry for the given refname from the packed
1288 * references.  If it does not exist, return NULL.
1289 */
1290static struct ref_entry *get_packed_ref(const char *refname)
1291{
1292        return find_ref(get_packed_refs(&ref_cache), refname);
1293}
1294
1295/*
1296 * A loose ref file doesn't exist; check for a packed ref.  The
1297 * options are forwarded from resolve_safe_unsafe().
1298 */
1299static const char *handle_missing_loose_ref(const char *refname,
1300                                            unsigned char *sha1,
1301                                            int reading,
1302                                            int *flag)
1303{
1304        struct ref_entry *entry;
1305
1306        /*
1307         * The loose reference file does not exist; check for a packed
1308         * reference.
1309         */
1310        entry = get_packed_ref(refname);
1311        if (entry) {
1312                hashcpy(sha1, entry->u.value.sha1);
1313                if (flag)
1314                        *flag |= REF_ISPACKED;
1315                return refname;
1316        }
1317        /* The reference is not a packed reference, either. */
1318        if (reading) {
1319                return NULL;
1320        } else {
1321                hashclr(sha1);
1322                return refname;
1323        }
1324}
1325
1326const char *resolve_ref_unsafe(const char *refname, unsigned char *sha1, int reading, int *flag)
1327{
1328        int depth = MAXDEPTH;
1329        ssize_t len;
1330        char buffer[256];
1331        static char refname_buffer[256];
1332
1333        if (flag)
1334                *flag = 0;
1335
1336        if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL))
1337                return NULL;
1338
1339        for (;;) {
1340                char path[PATH_MAX];
1341                struct stat st;
1342                char *buf;
1343                int fd;
1344
1345                if (--depth < 0)
1346                        return NULL;
1347
1348                git_snpath(path, sizeof(path), "%s", refname);
1349
1350                /*
1351                 * We might have to loop back here to avoid a race
1352                 * condition: first we lstat() the file, then we try
1353                 * to read it as a link or as a file.  But if somebody
1354                 * changes the type of the file (file <-> directory
1355                 * <-> symlink) between the lstat() and reading, then
1356                 * we don't want to report that as an error but rather
1357                 * try again starting with the lstat().
1358                 */
1359        stat_ref:
1360                if (lstat(path, &st) < 0) {
1361                        if (errno == ENOENT)
1362                                return handle_missing_loose_ref(refname, sha1,
1363                                                                reading, flag);
1364                        else
1365                                return NULL;
1366                }
1367
1368                /* Follow "normalized" - ie "refs/.." symlinks by hand */
1369                if (S_ISLNK(st.st_mode)) {
1370                        len = readlink(path, buffer, sizeof(buffer)-1);
1371                        if (len < 0) {
1372                                if (errno == ENOENT || errno == EINVAL)
1373                                        /* inconsistent with lstat; retry */
1374                                        goto stat_ref;
1375                                else
1376                                        return NULL;
1377                        }
1378                        buffer[len] = 0;
1379                        if (starts_with(buffer, "refs/") &&
1380                                        !check_refname_format(buffer, 0)) {
1381                                strcpy(refname_buffer, buffer);
1382                                refname = refname_buffer;
1383                                if (flag)
1384                                        *flag |= REF_ISSYMREF;
1385                                continue;
1386                        }
1387                }
1388
1389                /* Is it a directory? */
1390                if (S_ISDIR(st.st_mode)) {
1391                        errno = EISDIR;
1392                        return NULL;
1393                }
1394
1395                /*
1396                 * Anything else, just open it and try to use it as
1397                 * a ref
1398                 */
1399                fd = open(path, O_RDONLY);
1400                if (fd < 0) {
1401                        if (errno == ENOENT)
1402                                /* inconsistent with lstat; retry */
1403                                goto stat_ref;
1404                        else
1405                                return NULL;
1406                }
1407                len = read_in_full(fd, buffer, sizeof(buffer)-1);
1408                close(fd);
1409                if (len < 0)
1410                        return NULL;
1411                while (len && isspace(buffer[len-1]))
1412                        len--;
1413                buffer[len] = '\0';
1414
1415                /*
1416                 * Is it a symbolic ref?
1417                 */
1418                if (!starts_with(buffer, "ref:")) {
1419                        /*
1420                         * Please note that FETCH_HEAD has a second
1421                         * line containing other data.
1422                         */
1423                        if (get_sha1_hex(buffer, sha1) ||
1424                            (buffer[40] != '\0' && !isspace(buffer[40]))) {
1425                                if (flag)
1426                                        *flag |= REF_ISBROKEN;
1427                                return NULL;
1428                        }
1429                        return refname;
1430                }
1431                if (flag)
1432                        *flag |= REF_ISSYMREF;
1433                buf = buffer + 4;
1434                while (isspace(*buf))
1435                        buf++;
1436                if (check_refname_format(buf, REFNAME_ALLOW_ONELEVEL)) {
1437                        if (flag)
1438                                *flag |= REF_ISBROKEN;
1439                        return NULL;
1440                }
1441                refname = strcpy(refname_buffer, buf);
1442        }
1443}
1444
1445char *resolve_refdup(const char *ref, unsigned char *sha1, int reading, int *flag)
1446{
1447        const char *ret = resolve_ref_unsafe(ref, sha1, reading, flag);
1448        return ret ? xstrdup(ret) : NULL;
1449}
1450
1451/* The argument to filter_refs */
1452struct ref_filter {
1453        const char *pattern;
1454        each_ref_fn *fn;
1455        void *cb_data;
1456};
1457
1458int read_ref_full(const char *refname, unsigned char *sha1, int reading, int *flags)
1459{
1460        if (resolve_ref_unsafe(refname, sha1, reading, flags))
1461                return 0;
1462        return -1;
1463}
1464
1465int read_ref(const char *refname, unsigned char *sha1)
1466{
1467        return read_ref_full(refname, sha1, 1, NULL);
1468}
1469
1470int ref_exists(const char *refname)
1471{
1472        unsigned char sha1[20];
1473        return !!resolve_ref_unsafe(refname, sha1, 1, NULL);
1474}
1475
1476static int filter_refs(const char *refname, const unsigned char *sha1, int flags,
1477                       void *data)
1478{
1479        struct ref_filter *filter = (struct ref_filter *)data;
1480        if (fnmatch(filter->pattern, refname, 0))
1481                return 0;
1482        return filter->fn(refname, sha1, flags, filter->cb_data);
1483}
1484
1485enum peel_status {
1486        /* object was peeled successfully: */
1487        PEEL_PEELED = 0,
1488
1489        /*
1490         * object cannot be peeled because the named object (or an
1491         * object referred to by a tag in the peel chain), does not
1492         * exist.
1493         */
1494        PEEL_INVALID = -1,
1495
1496        /* object cannot be peeled because it is not a tag: */
1497        PEEL_NON_TAG = -2,
1498
1499        /* ref_entry contains no peeled value because it is a symref: */
1500        PEEL_IS_SYMREF = -3,
1501
1502        /*
1503         * ref_entry cannot be peeled because it is broken (i.e., the
1504         * symbolic reference cannot even be resolved to an object
1505         * name):
1506         */
1507        PEEL_BROKEN = -4
1508};
1509
1510/*
1511 * Peel the named object; i.e., if the object is a tag, resolve the
1512 * tag recursively until a non-tag is found.  If successful, store the
1513 * result to sha1 and return PEEL_PEELED.  If the object is not a tag
1514 * or is not valid, return PEEL_NON_TAG or PEEL_INVALID, respectively,
1515 * and leave sha1 unchanged.
1516 */
1517static enum peel_status peel_object(const unsigned char *name, unsigned char *sha1)
1518{
1519        struct object *o = lookup_unknown_object(name);
1520
1521        if (o->type == OBJ_NONE) {
1522                int type = sha1_object_info(name, NULL);
1523                if (type < 0)
1524                        return PEEL_INVALID;
1525                o->type = type;
1526        }
1527
1528        if (o->type != OBJ_TAG)
1529                return PEEL_NON_TAG;
1530
1531        o = deref_tag_noverify(o);
1532        if (!o)
1533                return PEEL_INVALID;
1534
1535        hashcpy(sha1, o->sha1);
1536        return PEEL_PEELED;
1537}
1538
1539/*
1540 * Peel the entry (if possible) and return its new peel_status.  If
1541 * repeel is true, re-peel the entry even if there is an old peeled
1542 * value that is already stored in it.
1543 *
1544 * It is OK to call this function with a packed reference entry that
1545 * might be stale and might even refer to an object that has since
1546 * been garbage-collected.  In such a case, if the entry has
1547 * REF_KNOWS_PEELED then leave the status unchanged and return
1548 * PEEL_PEELED or PEEL_NON_TAG; otherwise, return PEEL_INVALID.
1549 */
1550static enum peel_status peel_entry(struct ref_entry *entry, int repeel)
1551{
1552        enum peel_status status;
1553
1554        if (entry->flag & REF_KNOWS_PEELED) {
1555                if (repeel) {
1556                        entry->flag &= ~REF_KNOWS_PEELED;
1557                        hashclr(entry->u.value.peeled);
1558                } else {
1559                        return is_null_sha1(entry->u.value.peeled) ?
1560                                PEEL_NON_TAG : PEEL_PEELED;
1561                }
1562        }
1563        if (entry->flag & REF_ISBROKEN)
1564                return PEEL_BROKEN;
1565        if (entry->flag & REF_ISSYMREF)
1566                return PEEL_IS_SYMREF;
1567
1568        status = peel_object(entry->u.value.sha1, entry->u.value.peeled);
1569        if (status == PEEL_PEELED || status == PEEL_NON_TAG)
1570                entry->flag |= REF_KNOWS_PEELED;
1571        return status;
1572}
1573
1574int peel_ref(const char *refname, unsigned char *sha1)
1575{
1576        int flag;
1577        unsigned char base[20];
1578
1579        if (current_ref && (current_ref->name == refname
1580                            || !strcmp(current_ref->name, refname))) {
1581                if (peel_entry(current_ref, 0))
1582                        return -1;
1583                hashcpy(sha1, current_ref->u.value.peeled);
1584                return 0;
1585        }
1586
1587        if (read_ref_full(refname, base, 1, &flag))
1588                return -1;
1589
1590        /*
1591         * If the reference is packed, read its ref_entry from the
1592         * cache in the hope that we already know its peeled value.
1593         * We only try this optimization on packed references because
1594         * (a) forcing the filling of the loose reference cache could
1595         * be expensive and (b) loose references anyway usually do not
1596         * have REF_KNOWS_PEELED.
1597         */
1598        if (flag & REF_ISPACKED) {
1599                struct ref_entry *r = get_packed_ref(refname);
1600                if (r) {
1601                        if (peel_entry(r, 0))
1602                                return -1;
1603                        hashcpy(sha1, r->u.value.peeled);
1604                        return 0;
1605                }
1606        }
1607
1608        return peel_object(base, sha1);
1609}
1610
1611struct warn_if_dangling_data {
1612        FILE *fp;
1613        const char *refname;
1614        const char *msg_fmt;
1615};
1616
1617static int warn_if_dangling_symref(const char *refname, const unsigned char *sha1,
1618                                   int flags, void *cb_data)
1619{
1620        struct warn_if_dangling_data *d = cb_data;
1621        const char *resolves_to;
1622        unsigned char junk[20];
1623
1624        if (!(flags & REF_ISSYMREF))
1625                return 0;
1626
1627        resolves_to = resolve_ref_unsafe(refname, junk, 0, NULL);
1628        if (!resolves_to || strcmp(resolves_to, d->refname))
1629                return 0;
1630
1631        fprintf(d->fp, d->msg_fmt, refname);
1632        fputc('\n', d->fp);
1633        return 0;
1634}
1635
1636void warn_dangling_symref(FILE *fp, const char *msg_fmt, const char *refname)
1637{
1638        struct warn_if_dangling_data data;
1639
1640        data.fp = fp;
1641        data.refname = refname;
1642        data.msg_fmt = msg_fmt;
1643        for_each_rawref(warn_if_dangling_symref, &data);
1644}
1645
1646/*
1647 * Call fn for each reference in the specified ref_cache, omitting
1648 * references not in the containing_dir of base.  fn is called for all
1649 * references, including broken ones.  If fn ever returns a non-zero
1650 * value, stop the iteration and return that value; otherwise, return
1651 * 0.
1652 */
1653static int do_for_each_entry(struct ref_cache *refs, const char *base,
1654                             each_ref_entry_fn fn, void *cb_data)
1655{
1656        struct packed_ref_cache *packed_ref_cache;
1657        struct ref_dir *loose_dir;
1658        struct ref_dir *packed_dir;
1659        int retval = 0;
1660
1661        /*
1662         * We must make sure that all loose refs are read before accessing the
1663         * packed-refs file; this avoids a race condition in which loose refs
1664         * are migrated to the packed-refs file by a simultaneous process, but
1665         * our in-memory view is from before the migration. get_packed_ref_cache()
1666         * takes care of making sure our view is up to date with what is on
1667         * disk.
1668         */
1669        loose_dir = get_loose_refs(refs);
1670        if (base && *base) {
1671                loose_dir = find_containing_dir(loose_dir, base, 0);
1672        }
1673        if (loose_dir)
1674                prime_ref_dir(loose_dir);
1675
1676        packed_ref_cache = get_packed_ref_cache(refs);
1677        acquire_packed_ref_cache(packed_ref_cache);
1678        packed_dir = get_packed_ref_dir(packed_ref_cache);
1679        if (base && *base) {
1680                packed_dir = find_containing_dir(packed_dir, base, 0);
1681        }
1682
1683        if (packed_dir && loose_dir) {
1684                sort_ref_dir(packed_dir);
1685                sort_ref_dir(loose_dir);
1686                retval = do_for_each_entry_in_dirs(
1687                                packed_dir, loose_dir, fn, cb_data);
1688        } else if (packed_dir) {
1689                sort_ref_dir(packed_dir);
1690                retval = do_for_each_entry_in_dir(
1691                                packed_dir, 0, fn, cb_data);
1692        } else if (loose_dir) {
1693                sort_ref_dir(loose_dir);
1694                retval = do_for_each_entry_in_dir(
1695                                loose_dir, 0, fn, cb_data);
1696        }
1697
1698        release_packed_ref_cache(packed_ref_cache);
1699        return retval;
1700}
1701
1702/*
1703 * Call fn for each reference in the specified ref_cache for which the
1704 * refname begins with base.  If trim is non-zero, then trim that many
1705 * characters off the beginning of each refname before passing the
1706 * refname to fn.  flags can be DO_FOR_EACH_INCLUDE_BROKEN to include
1707 * broken references in the iteration.  If fn ever returns a non-zero
1708 * value, stop the iteration and return that value; otherwise, return
1709 * 0.
1710 */
1711static int do_for_each_ref(struct ref_cache *refs, const char *base,
1712                           each_ref_fn fn, int trim, int flags, void *cb_data)
1713{
1714        struct ref_entry_cb data;
1715        data.base = base;
1716        data.trim = trim;
1717        data.flags = flags;
1718        data.fn = fn;
1719        data.cb_data = cb_data;
1720
1721        return do_for_each_entry(refs, base, do_one_ref, &data);
1722}
1723
1724static int do_head_ref(const char *submodule, each_ref_fn fn, void *cb_data)
1725{
1726        unsigned char sha1[20];
1727        int flag;
1728
1729        if (submodule) {
1730                if (resolve_gitlink_ref(submodule, "HEAD", sha1) == 0)
1731                        return fn("HEAD", sha1, 0, cb_data);
1732
1733                return 0;
1734        }
1735
1736        if (!read_ref_full("HEAD", sha1, 1, &flag))
1737                return fn("HEAD", sha1, flag, cb_data);
1738
1739        return 0;
1740}
1741
1742int head_ref(each_ref_fn fn, void *cb_data)
1743{
1744        return do_head_ref(NULL, fn, cb_data);
1745}
1746
1747int head_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
1748{
1749        return do_head_ref(submodule, fn, cb_data);
1750}
1751
1752int for_each_ref(each_ref_fn fn, void *cb_data)
1753{
1754        return do_for_each_ref(&ref_cache, "", fn, 0, 0, cb_data);
1755}
1756
1757int for_each_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
1758{
1759        return do_for_each_ref(get_ref_cache(submodule), "", fn, 0, 0, cb_data);
1760}
1761
1762int for_each_ref_in(const char *prefix, each_ref_fn fn, void *cb_data)
1763{
1764        return do_for_each_ref(&ref_cache, prefix, fn, strlen(prefix), 0, cb_data);
1765}
1766
1767int for_each_ref_in_submodule(const char *submodule, const char *prefix,
1768                each_ref_fn fn, void *cb_data)
1769{
1770        return do_for_each_ref(get_ref_cache(submodule), prefix, fn, strlen(prefix), 0, cb_data);
1771}
1772
1773int for_each_tag_ref(each_ref_fn fn, void *cb_data)
1774{
1775        return for_each_ref_in("refs/tags/", fn, cb_data);
1776}
1777
1778int for_each_tag_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
1779{
1780        return for_each_ref_in_submodule(submodule, "refs/tags/", fn, cb_data);
1781}
1782
1783int for_each_branch_ref(each_ref_fn fn, void *cb_data)
1784{
1785        return for_each_ref_in("refs/heads/", fn, cb_data);
1786}
1787
1788int for_each_branch_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
1789{
1790        return for_each_ref_in_submodule(submodule, "refs/heads/", fn, cb_data);
1791}
1792
1793int for_each_remote_ref(each_ref_fn fn, void *cb_data)
1794{
1795        return for_each_ref_in("refs/remotes/", fn, cb_data);
1796}
1797
1798int for_each_remote_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
1799{
1800        return for_each_ref_in_submodule(submodule, "refs/remotes/", fn, cb_data);
1801}
1802
1803int for_each_replace_ref(each_ref_fn fn, void *cb_data)
1804{
1805        return do_for_each_ref(&ref_cache, "refs/replace/", fn, 13, 0, cb_data);
1806}
1807
1808int head_ref_namespaced(each_ref_fn fn, void *cb_data)
1809{
1810        struct strbuf buf = STRBUF_INIT;
1811        int ret = 0;
1812        unsigned char sha1[20];
1813        int flag;
1814
1815        strbuf_addf(&buf, "%sHEAD", get_git_namespace());
1816        if (!read_ref_full(buf.buf, sha1, 1, &flag))
1817                ret = fn(buf.buf, sha1, flag, cb_data);
1818        strbuf_release(&buf);
1819
1820        return ret;
1821}
1822
1823int for_each_namespaced_ref(each_ref_fn fn, void *cb_data)
1824{
1825        struct strbuf buf = STRBUF_INIT;
1826        int ret;
1827        strbuf_addf(&buf, "%srefs/", get_git_namespace());
1828        ret = do_for_each_ref(&ref_cache, buf.buf, fn, 0, 0, cb_data);
1829        strbuf_release(&buf);
1830        return ret;
1831}
1832
1833int for_each_glob_ref_in(each_ref_fn fn, const char *pattern,
1834        const char *prefix, void *cb_data)
1835{
1836        struct strbuf real_pattern = STRBUF_INIT;
1837        struct ref_filter filter;
1838        int ret;
1839
1840        if (!prefix && !starts_with(pattern, "refs/"))
1841                strbuf_addstr(&real_pattern, "refs/");
1842        else if (prefix)
1843                strbuf_addstr(&real_pattern, prefix);
1844        strbuf_addstr(&real_pattern, pattern);
1845
1846        if (!has_glob_specials(pattern)) {
1847                /* Append implied '/' '*' if not present. */
1848                if (real_pattern.buf[real_pattern.len - 1] != '/')
1849                        strbuf_addch(&real_pattern, '/');
1850                /* No need to check for '*', there is none. */
1851                strbuf_addch(&real_pattern, '*');
1852        }
1853
1854        filter.pattern = real_pattern.buf;
1855        filter.fn = fn;
1856        filter.cb_data = cb_data;
1857        ret = for_each_ref(filter_refs, &filter);
1858
1859        strbuf_release(&real_pattern);
1860        return ret;
1861}
1862
1863int for_each_glob_ref(each_ref_fn fn, const char *pattern, void *cb_data)
1864{
1865        return for_each_glob_ref_in(fn, pattern, NULL, cb_data);
1866}
1867
1868int for_each_rawref(each_ref_fn fn, void *cb_data)
1869{
1870        return do_for_each_ref(&ref_cache, "", fn, 0,
1871                               DO_FOR_EACH_INCLUDE_BROKEN, cb_data);
1872}
1873
1874const char *prettify_refname(const char *name)
1875{
1876        return name + (
1877                starts_with(name, "refs/heads/") ? 11 :
1878                starts_with(name, "refs/tags/") ? 10 :
1879                starts_with(name, "refs/remotes/") ? 13 :
1880                0);
1881}
1882
1883const char *ref_rev_parse_rules[] = {
1884        "%.*s",
1885        "refs/%.*s",
1886        "refs/tags/%.*s",
1887        "refs/heads/%.*s",
1888        "refs/remotes/%.*s",
1889        "refs/remotes/%.*s/HEAD",
1890        NULL
1891};
1892
1893int refname_match(const char *abbrev_name, const char *full_name, const char **rules)
1894{
1895        const char **p;
1896        const int abbrev_name_len = strlen(abbrev_name);
1897
1898        for (p = rules; *p; p++) {
1899                if (!strcmp(full_name, mkpath(*p, abbrev_name_len, abbrev_name))) {
1900                        return 1;
1901                }
1902        }
1903
1904        return 0;
1905}
1906
1907static struct ref_lock *verify_lock(struct ref_lock *lock,
1908        const unsigned char *old_sha1, int mustexist)
1909{
1910        if (read_ref_full(lock->ref_name, lock->old_sha1, mustexist, NULL)) {
1911                error("Can't verify ref %s", lock->ref_name);
1912                unlock_ref(lock);
1913                return NULL;
1914        }
1915        if (hashcmp(lock->old_sha1, old_sha1)) {
1916                error("Ref %s is at %s but expected %s", lock->ref_name,
1917                        sha1_to_hex(lock->old_sha1), sha1_to_hex(old_sha1));
1918                unlock_ref(lock);
1919                return NULL;
1920        }
1921        return lock;
1922}
1923
1924static int remove_empty_directories(const char *file)
1925{
1926        /* we want to create a file but there is a directory there;
1927         * if that is an empty directory (or a directory that contains
1928         * only empty directories), remove them.
1929         */
1930        struct strbuf path;
1931        int result;
1932
1933        strbuf_init(&path, 20);
1934        strbuf_addstr(&path, file);
1935
1936        result = remove_dir_recursively(&path, REMOVE_DIR_EMPTY_ONLY);
1937
1938        strbuf_release(&path);
1939
1940        return result;
1941}
1942
1943/*
1944 * *string and *len will only be substituted, and *string returned (for
1945 * later free()ing) if the string passed in is a magic short-hand form
1946 * to name a branch.
1947 */
1948static char *substitute_branch_name(const char **string, int *len)
1949{
1950        struct strbuf buf = STRBUF_INIT;
1951        int ret = interpret_branch_name(*string, *len, &buf);
1952
1953        if (ret == *len) {
1954                size_t size;
1955                *string = strbuf_detach(&buf, &size);
1956                *len = size;
1957                return (char *)*string;
1958        }
1959
1960        return NULL;
1961}
1962
1963int dwim_ref(const char *str, int len, unsigned char *sha1, char **ref)
1964{
1965        char *last_branch = substitute_branch_name(&str, &len);
1966        const char **p, *r;
1967        int refs_found = 0;
1968
1969        *ref = NULL;
1970        for (p = ref_rev_parse_rules; *p; p++) {
1971                char fullref[PATH_MAX];
1972                unsigned char sha1_from_ref[20];
1973                unsigned char *this_result;
1974                int flag;
1975
1976                this_result = refs_found ? sha1_from_ref : sha1;
1977                mksnpath(fullref, sizeof(fullref), *p, len, str);
1978                r = resolve_ref_unsafe(fullref, this_result, 1, &flag);
1979                if (r) {
1980                        if (!refs_found++)
1981                                *ref = xstrdup(r);
1982                        if (!warn_ambiguous_refs)
1983                                break;
1984                } else if ((flag & REF_ISSYMREF) && strcmp(fullref, "HEAD")) {
1985                        warning("ignoring dangling symref %s.", fullref);
1986                } else if ((flag & REF_ISBROKEN) && strchr(fullref, '/')) {
1987                        warning("ignoring broken ref %s.", fullref);
1988                }
1989        }
1990        free(last_branch);
1991        return refs_found;
1992}
1993
1994int dwim_log(const char *str, int len, unsigned char *sha1, char **log)
1995{
1996        char *last_branch = substitute_branch_name(&str, &len);
1997        const char **p;
1998        int logs_found = 0;
1999
2000        *log = NULL;
2001        for (p = ref_rev_parse_rules; *p; p++) {
2002                struct stat st;
2003                unsigned char hash[20];
2004                char path[PATH_MAX];
2005                const char *ref, *it;
2006
2007                mksnpath(path, sizeof(path), *p, len, str);
2008                ref = resolve_ref_unsafe(path, hash, 1, NULL);
2009                if (!ref)
2010                        continue;
2011                if (!stat(git_path("logs/%s", path), &st) &&
2012                    S_ISREG(st.st_mode))
2013                        it = path;
2014                else if (strcmp(ref, path) &&
2015                         !stat(git_path("logs/%s", ref), &st) &&
2016                         S_ISREG(st.st_mode))
2017                        it = ref;
2018                else
2019                        continue;
2020                if (!logs_found++) {
2021                        *log = xstrdup(it);
2022                        hashcpy(sha1, hash);
2023                }
2024                if (!warn_ambiguous_refs)
2025                        break;
2026        }
2027        free(last_branch);
2028        return logs_found;
2029}
2030
2031static struct ref_lock *lock_ref_sha1_basic(const char *refname,
2032                                            const unsigned char *old_sha1,
2033                                            int flags, int *type_p)
2034{
2035        char *ref_file;
2036        const char *orig_refname = refname;
2037        struct ref_lock *lock;
2038        int last_errno = 0;
2039        int type, lflags;
2040        int mustexist = (old_sha1 && !is_null_sha1(old_sha1));
2041        int missing = 0;
2042
2043        lock = xcalloc(1, sizeof(struct ref_lock));
2044        lock->lock_fd = -1;
2045
2046        refname = resolve_ref_unsafe(refname, lock->old_sha1, mustexist, &type);
2047        if (!refname && errno == EISDIR) {
2048                /* we are trying to lock foo but we used to
2049                 * have foo/bar which now does not exist;
2050                 * it is normal for the empty directory 'foo'
2051                 * to remain.
2052                 */
2053                ref_file = git_path("%s", orig_refname);
2054                if (remove_empty_directories(ref_file)) {
2055                        last_errno = errno;
2056                        error("there are still refs under '%s'", orig_refname);
2057                        goto error_return;
2058                }
2059                refname = resolve_ref_unsafe(orig_refname, lock->old_sha1, mustexist, &type);
2060        }
2061        if (type_p)
2062            *type_p = type;
2063        if (!refname) {
2064                last_errno = errno;
2065                error("unable to resolve reference %s: %s",
2066                        orig_refname, strerror(errno));
2067                goto error_return;
2068        }
2069        missing = is_null_sha1(lock->old_sha1);
2070        /* When the ref did not exist and we are creating it,
2071         * make sure there is no existing ref that is packed
2072         * whose name begins with our refname, nor a ref whose
2073         * name is a proper prefix of our refname.
2074         */
2075        if (missing &&
2076             !is_refname_available(refname, NULL, get_packed_refs(&ref_cache))) {
2077                last_errno = ENOTDIR;
2078                goto error_return;
2079        }
2080
2081        lock->lk = xcalloc(1, sizeof(struct lock_file));
2082
2083        lflags = LOCK_DIE_ON_ERROR;
2084        if (flags & REF_NODEREF) {
2085                refname = orig_refname;
2086                lflags |= LOCK_NODEREF;
2087        }
2088        lock->ref_name = xstrdup(refname);
2089        lock->orig_ref_name = xstrdup(orig_refname);
2090        ref_file = git_path("%s", refname);
2091        if (missing)
2092                lock->force_write = 1;
2093        if ((flags & REF_NODEREF) && (type & REF_ISSYMREF))
2094                lock->force_write = 1;
2095
2096        if (safe_create_leading_directories(ref_file)) {
2097                last_errno = errno;
2098                error("unable to create directory for %s", ref_file);
2099                goto error_return;
2100        }
2101
2102        lock->lock_fd = hold_lock_file_for_update(lock->lk, ref_file, lflags);
2103        return old_sha1 ? verify_lock(lock, old_sha1, mustexist) : lock;
2104
2105 error_return:
2106        unlock_ref(lock);
2107        errno = last_errno;
2108        return NULL;
2109}
2110
2111struct ref_lock *lock_ref_sha1(const char *refname, const unsigned char *old_sha1)
2112{
2113        char refpath[PATH_MAX];
2114        if (check_refname_format(refname, 0))
2115                return NULL;
2116        strcpy(refpath, mkpath("refs/%s", refname));
2117        return lock_ref_sha1_basic(refpath, old_sha1, 0, NULL);
2118}
2119
2120struct ref_lock *lock_any_ref_for_update(const char *refname,
2121                                         const unsigned char *old_sha1,
2122                                         int flags, int *type_p)
2123{
2124        if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL))
2125                return NULL;
2126        return lock_ref_sha1_basic(refname, old_sha1, flags, type_p);
2127}
2128
2129/*
2130 * Write an entry to the packed-refs file for the specified refname.
2131 * If peeled is non-NULL, write it as the entry's peeled value.
2132 */
2133static void write_packed_entry(int fd, char *refname, unsigned char *sha1,
2134                               unsigned char *peeled)
2135{
2136        char line[PATH_MAX + 100];
2137        int len;
2138
2139        len = snprintf(line, sizeof(line), "%s %s\n",
2140                       sha1_to_hex(sha1), refname);
2141        /* this should not happen but just being defensive */
2142        if (len > sizeof(line))
2143                die("too long a refname '%s'", refname);
2144        write_or_die(fd, line, len);
2145
2146        if (peeled) {
2147                if (snprintf(line, sizeof(line), "^%s\n",
2148                             sha1_to_hex(peeled)) != PEELED_LINE_LENGTH)
2149                        die("internal error");
2150                write_or_die(fd, line, PEELED_LINE_LENGTH);
2151        }
2152}
2153
2154/*
2155 * An each_ref_entry_fn that writes the entry to a packed-refs file.
2156 */
2157static int write_packed_entry_fn(struct ref_entry *entry, void *cb_data)
2158{
2159        int *fd = cb_data;
2160        enum peel_status peel_status = peel_entry(entry, 0);
2161
2162        if (peel_status != PEEL_PEELED && peel_status != PEEL_NON_TAG)
2163                error("internal error: %s is not a valid packed reference!",
2164                      entry->name);
2165        write_packed_entry(*fd, entry->name, entry->u.value.sha1,
2166                           peel_status == PEEL_PEELED ?
2167                           entry->u.value.peeled : NULL);
2168        return 0;
2169}
2170
2171int lock_packed_refs(int flags)
2172{
2173        struct packed_ref_cache *packed_ref_cache;
2174
2175        if (hold_lock_file_for_update(&packlock, git_path("packed-refs"), flags) < 0)
2176                return -1;
2177        /*
2178         * Get the current packed-refs while holding the lock.  If the
2179         * packed-refs file has been modified since we last read it,
2180         * this will automatically invalidate the cache and re-read
2181         * the packed-refs file.
2182         */
2183        packed_ref_cache = get_packed_ref_cache(&ref_cache);
2184        packed_ref_cache->lock = &packlock;
2185        /* Increment the reference count to prevent it from being freed: */
2186        acquire_packed_ref_cache(packed_ref_cache);
2187        return 0;
2188}
2189
2190int commit_packed_refs(void)
2191{
2192        struct packed_ref_cache *packed_ref_cache =
2193                get_packed_ref_cache(&ref_cache);
2194        int error = 0;
2195
2196        if (!packed_ref_cache->lock)
2197                die("internal error: packed-refs not locked");
2198        write_or_die(packed_ref_cache->lock->fd,
2199                     PACKED_REFS_HEADER, strlen(PACKED_REFS_HEADER));
2200
2201        do_for_each_entry_in_dir(get_packed_ref_dir(packed_ref_cache),
2202                                 0, write_packed_entry_fn,
2203                                 &packed_ref_cache->lock->fd);
2204        if (commit_lock_file(packed_ref_cache->lock))
2205                error = -1;
2206        packed_ref_cache->lock = NULL;
2207        release_packed_ref_cache(packed_ref_cache);
2208        return error;
2209}
2210
2211void rollback_packed_refs(void)
2212{
2213        struct packed_ref_cache *packed_ref_cache =
2214                get_packed_ref_cache(&ref_cache);
2215
2216        if (!packed_ref_cache->lock)
2217                die("internal error: packed-refs not locked");
2218        rollback_lock_file(packed_ref_cache->lock);
2219        packed_ref_cache->lock = NULL;
2220        release_packed_ref_cache(packed_ref_cache);
2221        clear_packed_ref_cache(&ref_cache);
2222}
2223
2224struct ref_to_prune {
2225        struct ref_to_prune *next;
2226        unsigned char sha1[20];
2227        char name[FLEX_ARRAY];
2228};
2229
2230struct pack_refs_cb_data {
2231        unsigned int flags;
2232        struct ref_dir *packed_refs;
2233        struct ref_to_prune *ref_to_prune;
2234};
2235
2236/*
2237 * An each_ref_entry_fn that is run over loose references only.  If
2238 * the loose reference can be packed, add an entry in the packed ref
2239 * cache.  If the reference should be pruned, also add it to
2240 * ref_to_prune in the pack_refs_cb_data.
2241 */
2242static int pack_if_possible_fn(struct ref_entry *entry, void *cb_data)
2243{
2244        struct pack_refs_cb_data *cb = cb_data;
2245        enum peel_status peel_status;
2246        struct ref_entry *packed_entry;
2247        int is_tag_ref = starts_with(entry->name, "refs/tags/");
2248
2249        /* ALWAYS pack tags */
2250        if (!(cb->flags & PACK_REFS_ALL) && !is_tag_ref)
2251                return 0;
2252
2253        /* Do not pack symbolic or broken refs: */
2254        if ((entry->flag & REF_ISSYMREF) || !ref_resolves_to_object(entry))
2255                return 0;
2256
2257        /* Add a packed ref cache entry equivalent to the loose entry. */
2258        peel_status = peel_entry(entry, 1);
2259        if (peel_status != PEEL_PEELED && peel_status != PEEL_NON_TAG)
2260                die("internal error peeling reference %s (%s)",
2261                    entry->name, sha1_to_hex(entry->u.value.sha1));
2262        packed_entry = find_ref(cb->packed_refs, entry->name);
2263        if (packed_entry) {
2264                /* Overwrite existing packed entry with info from loose entry */
2265                packed_entry->flag = REF_ISPACKED | REF_KNOWS_PEELED;
2266                hashcpy(packed_entry->u.value.sha1, entry->u.value.sha1);
2267        } else {
2268                packed_entry = create_ref_entry(entry->name, entry->u.value.sha1,
2269                                                REF_ISPACKED | REF_KNOWS_PEELED, 0);
2270                add_ref(cb->packed_refs, packed_entry);
2271        }
2272        hashcpy(packed_entry->u.value.peeled, entry->u.value.peeled);
2273
2274        /* Schedule the loose reference for pruning if requested. */
2275        if ((cb->flags & PACK_REFS_PRUNE)) {
2276                int namelen = strlen(entry->name) + 1;
2277                struct ref_to_prune *n = xcalloc(1, sizeof(*n) + namelen);
2278                hashcpy(n->sha1, entry->u.value.sha1);
2279                strcpy(n->name, entry->name);
2280                n->next = cb->ref_to_prune;
2281                cb->ref_to_prune = n;
2282        }
2283        return 0;
2284}
2285
2286/*
2287 * Remove empty parents, but spare refs/ and immediate subdirs.
2288 * Note: munges *name.
2289 */
2290static void try_remove_empty_parents(char *name)
2291{
2292        char *p, *q;
2293        int i;
2294        p = name;
2295        for (i = 0; i < 2; i++) { /* refs/{heads,tags,...}/ */
2296                while (*p && *p != '/')
2297                        p++;
2298                /* tolerate duplicate slashes; see check_refname_format() */
2299                while (*p == '/')
2300                        p++;
2301        }
2302        for (q = p; *q; q++)
2303                ;
2304        while (1) {
2305                while (q > p && *q != '/')
2306                        q--;
2307                while (q > p && *(q-1) == '/')
2308                        q--;
2309                if (q == p)
2310                        break;
2311                *q = '\0';
2312                if (rmdir(git_path("%s", name)))
2313                        break;
2314        }
2315}
2316
2317/* make sure nobody touched the ref, and unlink */
2318static void prune_ref(struct ref_to_prune *r)
2319{
2320        struct ref_lock *lock = lock_ref_sha1(r->name + 5, r->sha1);
2321
2322        if (lock) {
2323                unlink_or_warn(git_path("%s", r->name));
2324                unlock_ref(lock);
2325                try_remove_empty_parents(r->name);
2326        }
2327}
2328
2329static void prune_refs(struct ref_to_prune *r)
2330{
2331        while (r) {
2332                prune_ref(r);
2333                r = r->next;
2334        }
2335}
2336
2337int pack_refs(unsigned int flags)
2338{
2339        struct pack_refs_cb_data cbdata;
2340
2341        memset(&cbdata, 0, sizeof(cbdata));
2342        cbdata.flags = flags;
2343
2344        lock_packed_refs(LOCK_DIE_ON_ERROR);
2345        cbdata.packed_refs = get_packed_refs(&ref_cache);
2346
2347        do_for_each_entry_in_dir(get_loose_refs(&ref_cache), 0,
2348                                 pack_if_possible_fn, &cbdata);
2349
2350        if (commit_packed_refs())
2351                die_errno("unable to overwrite old ref-pack file");
2352
2353        prune_refs(cbdata.ref_to_prune);
2354        return 0;
2355}
2356
2357/*
2358 * If entry is no longer needed in packed-refs, add it to the string
2359 * list pointed to by cb_data.  Reasons for deleting entries:
2360 *
2361 * - Entry is broken.
2362 * - Entry is overridden by a loose ref.
2363 * - Entry does not point at a valid object.
2364 *
2365 * In the first and third cases, also emit an error message because these
2366 * are indications of repository corruption.
2367 */
2368static int curate_packed_ref_fn(struct ref_entry *entry, void *cb_data)
2369{
2370        struct string_list *refs_to_delete = cb_data;
2371
2372        if (entry->flag & REF_ISBROKEN) {
2373                /* This shouldn't happen to packed refs. */
2374                error("%s is broken!", entry->name);
2375                string_list_append(refs_to_delete, entry->name);
2376                return 0;
2377        }
2378        if (!has_sha1_file(entry->u.value.sha1)) {
2379                unsigned char sha1[20];
2380                int flags;
2381
2382                if (read_ref_full(entry->name, sha1, 0, &flags))
2383                        /* We should at least have found the packed ref. */
2384                        die("Internal error");
2385                if ((flags & REF_ISSYMREF) || !(flags & REF_ISPACKED)) {
2386                        /*
2387                         * This packed reference is overridden by a
2388                         * loose reference, so it is OK that its value
2389                         * is no longer valid; for example, it might
2390                         * refer to an object that has been garbage
2391                         * collected.  For this purpose we don't even
2392                         * care whether the loose reference itself is
2393                         * invalid, broken, symbolic, etc.  Silently
2394                         * remove the packed reference.
2395                         */
2396                        string_list_append(refs_to_delete, entry->name);
2397                        return 0;
2398                }
2399                /*
2400                 * There is no overriding loose reference, so the fact
2401                 * that this reference doesn't refer to a valid object
2402                 * indicates some kind of repository corruption.
2403                 * Report the problem, then omit the reference from
2404                 * the output.
2405                 */
2406                error("%s does not point to a valid object!", entry->name);
2407                string_list_append(refs_to_delete, entry->name);
2408                return 0;
2409        }
2410
2411        return 0;
2412}
2413
2414static int repack_without_refs(const char **refnames, int n)
2415{
2416        struct ref_dir *packed;
2417        struct string_list refs_to_delete = STRING_LIST_INIT_DUP;
2418        struct string_list_item *ref_to_delete;
2419        int i, removed = 0;
2420
2421        /* Look for a packed ref */
2422        for (i = 0; i < n; i++)
2423                if (get_packed_ref(refnames[i]))
2424                        break;
2425
2426        /* Avoid locking if we have nothing to do */
2427        if (i == n)
2428                return 0; /* no refname exists in packed refs */
2429
2430        if (lock_packed_refs(0)) {
2431                unable_to_lock_error(git_path("packed-refs"), errno);
2432                return error("cannot delete '%s' from packed refs", refnames[i]);
2433        }
2434        packed = get_packed_refs(&ref_cache);
2435
2436        /* Remove refnames from the cache */
2437        for (i = 0; i < n; i++)
2438                if (remove_entry(packed, refnames[i]) != -1)
2439                        removed = 1;
2440        if (!removed) {
2441                /*
2442                 * All packed entries disappeared while we were
2443                 * acquiring the lock.
2444                 */
2445                rollback_packed_refs();
2446                return 0;
2447        }
2448
2449        /* Remove any other accumulated cruft */
2450        do_for_each_entry_in_dir(packed, 0, curate_packed_ref_fn, &refs_to_delete);
2451        for_each_string_list_item(ref_to_delete, &refs_to_delete) {
2452                if (remove_entry(packed, ref_to_delete->string) == -1)
2453                        die("internal error");
2454        }
2455
2456        /* Write what remains */
2457        return commit_packed_refs();
2458}
2459
2460static int repack_without_ref(const char *refname)
2461{
2462        return repack_without_refs(&refname, 1);
2463}
2464
2465static int delete_ref_loose(struct ref_lock *lock, int flag)
2466{
2467        if (!(flag & REF_ISPACKED) || flag & REF_ISSYMREF) {
2468                /* loose */
2469                int err, i = strlen(lock->lk->filename) - 5; /* .lock */
2470
2471                lock->lk->filename[i] = 0;
2472                err = unlink_or_warn(lock->lk->filename);
2473                lock->lk->filename[i] = '.';
2474                if (err && errno != ENOENT)
2475                        return 1;
2476        }
2477        return 0;
2478}
2479
2480int delete_ref(const char *refname, const unsigned char *sha1, int delopt)
2481{
2482        struct ref_lock *lock;
2483        int ret = 0, flag = 0;
2484
2485        lock = lock_ref_sha1_basic(refname, sha1, delopt, &flag);
2486        if (!lock)
2487                return 1;
2488        ret |= delete_ref_loose(lock, flag);
2489
2490        /* removing the loose one could have resurrected an earlier
2491         * packed one.  Also, if it was not loose we need to repack
2492         * without it.
2493         */
2494        ret |= repack_without_ref(lock->ref_name);
2495
2496        unlink_or_warn(git_path("logs/%s", lock->ref_name));
2497        clear_loose_ref_cache(&ref_cache);
2498        unlock_ref(lock);
2499        return ret;
2500}
2501
2502/*
2503 * People using contrib's git-new-workdir have .git/logs/refs ->
2504 * /some/other/path/.git/logs/refs, and that may live on another device.
2505 *
2506 * IOW, to avoid cross device rename errors, the temporary renamed log must
2507 * live into logs/refs.
2508 */
2509#define TMP_RENAMED_LOG  "logs/refs/.tmp-renamed-log"
2510
2511int rename_ref(const char *oldrefname, const char *newrefname, const char *logmsg)
2512{
2513        unsigned char sha1[20], orig_sha1[20];
2514        int flag = 0, logmoved = 0;
2515        struct ref_lock *lock;
2516        struct stat loginfo;
2517        int log = !lstat(git_path("logs/%s", oldrefname), &loginfo);
2518        const char *symref = NULL;
2519
2520        if (log && S_ISLNK(loginfo.st_mode))
2521                return error("reflog for %s is a symlink", oldrefname);
2522
2523        symref = resolve_ref_unsafe(oldrefname, orig_sha1, 1, &flag);
2524        if (flag & REF_ISSYMREF)
2525                return error("refname %s is a symbolic ref, renaming it is not supported",
2526                        oldrefname);
2527        if (!symref)
2528                return error("refname %s not found", oldrefname);
2529
2530        if (!is_refname_available(newrefname, oldrefname, get_packed_refs(&ref_cache)))
2531                return 1;
2532
2533        if (!is_refname_available(newrefname, oldrefname, get_loose_refs(&ref_cache)))
2534                return 1;
2535
2536        if (log && rename(git_path("logs/%s", oldrefname), git_path(TMP_RENAMED_LOG)))
2537                return error("unable to move logfile logs/%s to "TMP_RENAMED_LOG": %s",
2538                        oldrefname, strerror(errno));
2539
2540        if (delete_ref(oldrefname, orig_sha1, REF_NODEREF)) {
2541                error("unable to delete old %s", oldrefname);
2542                goto rollback;
2543        }
2544
2545        if (!read_ref_full(newrefname, sha1, 1, &flag) &&
2546            delete_ref(newrefname, sha1, REF_NODEREF)) {
2547                if (errno==EISDIR) {
2548                        if (remove_empty_directories(git_path("%s", newrefname))) {
2549                                error("Directory not empty: %s", newrefname);
2550                                goto rollback;
2551                        }
2552                } else {
2553                        error("unable to delete existing %s", newrefname);
2554                        goto rollback;
2555                }
2556        }
2557
2558        if (log && safe_create_leading_directories(git_path("logs/%s", newrefname))) {
2559                error("unable to create directory for %s", newrefname);
2560                goto rollback;
2561        }
2562
2563 retry:
2564        if (log && rename(git_path(TMP_RENAMED_LOG), git_path("logs/%s", newrefname))) {
2565                if (errno==EISDIR || errno==ENOTDIR) {
2566                        /*
2567                         * rename(a, b) when b is an existing
2568                         * directory ought to result in ISDIR, but
2569                         * Solaris 5.8 gives ENOTDIR.  Sheesh.
2570                         */
2571                        if (remove_empty_directories(git_path("logs/%s", newrefname))) {
2572                                error("Directory not empty: logs/%s", newrefname);
2573                                goto rollback;
2574                        }
2575                        goto retry;
2576                } else {
2577                        error("unable to move logfile "TMP_RENAMED_LOG" to logs/%s: %s",
2578                                newrefname, strerror(errno));
2579                        goto rollback;
2580                }
2581        }
2582        logmoved = log;
2583
2584        lock = lock_ref_sha1_basic(newrefname, NULL, 0, NULL);
2585        if (!lock) {
2586                error("unable to lock %s for update", newrefname);
2587                goto rollback;
2588        }
2589        lock->force_write = 1;
2590        hashcpy(lock->old_sha1, orig_sha1);
2591        if (write_ref_sha1(lock, orig_sha1, logmsg)) {
2592                error("unable to write current sha1 into %s", newrefname);
2593                goto rollback;
2594        }
2595
2596        return 0;
2597
2598 rollback:
2599        lock = lock_ref_sha1_basic(oldrefname, NULL, 0, NULL);
2600        if (!lock) {
2601                error("unable to lock %s for rollback", oldrefname);
2602                goto rollbacklog;
2603        }
2604
2605        lock->force_write = 1;
2606        flag = log_all_ref_updates;
2607        log_all_ref_updates = 0;
2608        if (write_ref_sha1(lock, orig_sha1, NULL))
2609                error("unable to write current sha1 into %s", oldrefname);
2610        log_all_ref_updates = flag;
2611
2612 rollbacklog:
2613        if (logmoved && rename(git_path("logs/%s", newrefname), git_path("logs/%s", oldrefname)))
2614                error("unable to restore logfile %s from %s: %s",
2615                        oldrefname, newrefname, strerror(errno));
2616        if (!logmoved && log &&
2617            rename(git_path(TMP_RENAMED_LOG), git_path("logs/%s", oldrefname)))
2618                error("unable to restore logfile %s from "TMP_RENAMED_LOG": %s",
2619                        oldrefname, strerror(errno));
2620
2621        return 1;
2622}
2623
2624int close_ref(struct ref_lock *lock)
2625{
2626        if (close_lock_file(lock->lk))
2627                return -1;
2628        lock->lock_fd = -1;
2629        return 0;
2630}
2631
2632int commit_ref(struct ref_lock *lock)
2633{
2634        if (commit_lock_file(lock->lk))
2635                return -1;
2636        lock->lock_fd = -1;
2637        return 0;
2638}
2639
2640void unlock_ref(struct ref_lock *lock)
2641{
2642        /* Do not free lock->lk -- atexit() still looks at them */
2643        if (lock->lk)
2644                rollback_lock_file(lock->lk);
2645        free(lock->ref_name);
2646        free(lock->orig_ref_name);
2647        free(lock);
2648}
2649
2650/*
2651 * copy the reflog message msg to buf, which has been allocated sufficiently
2652 * large, while cleaning up the whitespaces.  Especially, convert LF to space,
2653 * because reflog file is one line per entry.
2654 */
2655static int copy_msg(char *buf, const char *msg)
2656{
2657        char *cp = buf;
2658        char c;
2659        int wasspace = 1;
2660
2661        *cp++ = '\t';
2662        while ((c = *msg++)) {
2663                if (wasspace && isspace(c))
2664                        continue;
2665                wasspace = isspace(c);
2666                if (wasspace)
2667                        c = ' ';
2668                *cp++ = c;
2669        }
2670        while (buf < cp && isspace(cp[-1]))
2671                cp--;
2672        *cp++ = '\n';
2673        return cp - buf;
2674}
2675
2676int log_ref_setup(const char *refname, char *logfile, int bufsize)
2677{
2678        int logfd, oflags = O_APPEND | O_WRONLY;
2679
2680        git_snpath(logfile, bufsize, "logs/%s", refname);
2681        if (log_all_ref_updates &&
2682            (starts_with(refname, "refs/heads/") ||
2683             starts_with(refname, "refs/remotes/") ||
2684             starts_with(refname, "refs/notes/") ||
2685             !strcmp(refname, "HEAD"))) {
2686                if (safe_create_leading_directories(logfile) < 0)
2687                        return error("unable to create directory for %s",
2688                                     logfile);
2689                oflags |= O_CREAT;
2690        }
2691
2692        logfd = open(logfile, oflags, 0666);
2693        if (logfd < 0) {
2694                if (!(oflags & O_CREAT) && errno == ENOENT)
2695                        return 0;
2696
2697                if ((oflags & O_CREAT) && errno == EISDIR) {
2698                        if (remove_empty_directories(logfile)) {
2699                                return error("There are still logs under '%s'",
2700                                             logfile);
2701                        }
2702                        logfd = open(logfile, oflags, 0666);
2703                }
2704
2705                if (logfd < 0)
2706                        return error("Unable to append to %s: %s",
2707                                     logfile, strerror(errno));
2708        }
2709
2710        adjust_shared_perm(logfile);
2711        close(logfd);
2712        return 0;
2713}
2714
2715static int log_ref_write(const char *refname, const unsigned char *old_sha1,
2716                         const unsigned char *new_sha1, const char *msg)
2717{
2718        int logfd, result, written, oflags = O_APPEND | O_WRONLY;
2719        unsigned maxlen, len;
2720        int msglen;
2721        char log_file[PATH_MAX];
2722        char *logrec;
2723        const char *committer;
2724
2725        if (log_all_ref_updates < 0)
2726                log_all_ref_updates = !is_bare_repository();
2727
2728        result = log_ref_setup(refname, log_file, sizeof(log_file));
2729        if (result)
2730                return result;
2731
2732        logfd = open(log_file, oflags);
2733        if (logfd < 0)
2734                return 0;
2735        msglen = msg ? strlen(msg) : 0;
2736        committer = git_committer_info(0);
2737        maxlen = strlen(committer) + msglen + 100;
2738        logrec = xmalloc(maxlen);
2739        len = sprintf(logrec, "%s %s %s\n",
2740                      sha1_to_hex(old_sha1),
2741                      sha1_to_hex(new_sha1),
2742                      committer);
2743        if (msglen)
2744                len += copy_msg(logrec + len - 1, msg) - 1;
2745        written = len <= maxlen ? write_in_full(logfd, logrec, len) : -1;
2746        free(logrec);
2747        if (close(logfd) != 0 || written != len)
2748                return error("Unable to append to %s", log_file);
2749        return 0;
2750}
2751
2752static int is_branch(const char *refname)
2753{
2754        return !strcmp(refname, "HEAD") || starts_with(refname, "refs/heads/");
2755}
2756
2757int write_ref_sha1(struct ref_lock *lock,
2758        const unsigned char *sha1, const char *logmsg)
2759{
2760        static char term = '\n';
2761        struct object *o;
2762
2763        if (!lock)
2764                return -1;
2765        if (!lock->force_write && !hashcmp(lock->old_sha1, sha1)) {
2766                unlock_ref(lock);
2767                return 0;
2768        }
2769        o = parse_object(sha1);
2770        if (!o) {
2771                error("Trying to write ref %s with nonexistent object %s",
2772                        lock->ref_name, sha1_to_hex(sha1));
2773                unlock_ref(lock);
2774                return -1;
2775        }
2776        if (o->type != OBJ_COMMIT && is_branch(lock->ref_name)) {
2777                error("Trying to write non-commit object %s to branch %s",
2778                        sha1_to_hex(sha1), lock->ref_name);
2779                unlock_ref(lock);
2780                return -1;
2781        }
2782        if (write_in_full(lock->lock_fd, sha1_to_hex(sha1), 40) != 40 ||
2783            write_in_full(lock->lock_fd, &term, 1) != 1
2784                || close_ref(lock) < 0) {
2785                error("Couldn't write %s", lock->lk->filename);
2786                unlock_ref(lock);
2787                return -1;
2788        }
2789        clear_loose_ref_cache(&ref_cache);
2790        if (log_ref_write(lock->ref_name, lock->old_sha1, sha1, logmsg) < 0 ||
2791            (strcmp(lock->ref_name, lock->orig_ref_name) &&
2792             log_ref_write(lock->orig_ref_name, lock->old_sha1, sha1, logmsg) < 0)) {
2793                unlock_ref(lock);
2794                return -1;
2795        }
2796        if (strcmp(lock->orig_ref_name, "HEAD") != 0) {
2797                /*
2798                 * Special hack: If a branch is updated directly and HEAD
2799                 * points to it (may happen on the remote side of a push
2800                 * for example) then logically the HEAD reflog should be
2801                 * updated too.
2802                 * A generic solution implies reverse symref information,
2803                 * but finding all symrefs pointing to the given branch
2804                 * would be rather costly for this rare event (the direct
2805                 * update of a branch) to be worth it.  So let's cheat and
2806                 * check with HEAD only which should cover 99% of all usage
2807                 * scenarios (even 100% of the default ones).
2808                 */
2809                unsigned char head_sha1[20];
2810                int head_flag;
2811                const char *head_ref;
2812                head_ref = resolve_ref_unsafe("HEAD", head_sha1, 1, &head_flag);
2813                if (head_ref && (head_flag & REF_ISSYMREF) &&
2814                    !strcmp(head_ref, lock->ref_name))
2815                        log_ref_write("HEAD", lock->old_sha1, sha1, logmsg);
2816        }
2817        if (commit_ref(lock)) {
2818                error("Couldn't set %s", lock->ref_name);
2819                unlock_ref(lock);
2820                return -1;
2821        }
2822        unlock_ref(lock);
2823        return 0;
2824}
2825
2826int create_symref(const char *ref_target, const char *refs_heads_master,
2827                  const char *logmsg)
2828{
2829        const char *lockpath;
2830        char ref[1000];
2831        int fd, len, written;
2832        char *git_HEAD = git_pathdup("%s", ref_target);
2833        unsigned char old_sha1[20], new_sha1[20];
2834
2835        if (logmsg && read_ref(ref_target, old_sha1))
2836                hashclr(old_sha1);
2837
2838        if (safe_create_leading_directories(git_HEAD) < 0)
2839                return error("unable to create directory for %s", git_HEAD);
2840
2841#ifndef NO_SYMLINK_HEAD
2842        if (prefer_symlink_refs) {
2843                unlink(git_HEAD);
2844                if (!symlink(refs_heads_master, git_HEAD))
2845                        goto done;
2846                fprintf(stderr, "no symlink - falling back to symbolic ref\n");
2847        }
2848#endif
2849
2850        len = snprintf(ref, sizeof(ref), "ref: %s\n", refs_heads_master);
2851        if (sizeof(ref) <= len) {
2852                error("refname too long: %s", refs_heads_master);
2853                goto error_free_return;
2854        }
2855        lockpath = mkpath("%s.lock", git_HEAD);
2856        fd = open(lockpath, O_CREAT | O_EXCL | O_WRONLY, 0666);
2857        if (fd < 0) {
2858                error("Unable to open %s for writing", lockpath);
2859                goto error_free_return;
2860        }
2861        written = write_in_full(fd, ref, len);
2862        if (close(fd) != 0 || written != len) {
2863                error("Unable to write to %s", lockpath);
2864                goto error_unlink_return;
2865        }
2866        if (rename(lockpath, git_HEAD) < 0) {
2867                error("Unable to create %s", git_HEAD);
2868                goto error_unlink_return;
2869        }
2870        if (adjust_shared_perm(git_HEAD)) {
2871                error("Unable to fix permissions on %s", lockpath);
2872        error_unlink_return:
2873                unlink_or_warn(lockpath);
2874        error_free_return:
2875                free(git_HEAD);
2876                return -1;
2877        }
2878
2879#ifndef NO_SYMLINK_HEAD
2880        done:
2881#endif
2882        if (logmsg && !read_ref(refs_heads_master, new_sha1))
2883                log_ref_write(ref_target, old_sha1, new_sha1, logmsg);
2884
2885        free(git_HEAD);
2886        return 0;
2887}
2888
2889static char *ref_msg(const char *line, const char *endp)
2890{
2891        const char *ep;
2892        line += 82;
2893        ep = memchr(line, '\n', endp - line);
2894        if (!ep)
2895                ep = endp;
2896        return xmemdupz(line, ep - line);
2897}
2898
2899int read_ref_at(const char *refname, unsigned long at_time, int cnt,
2900                unsigned char *sha1, char **msg,
2901                unsigned long *cutoff_time, int *cutoff_tz, int *cutoff_cnt)
2902{
2903        const char *logfile, *logdata, *logend, *rec, *lastgt, *lastrec;
2904        char *tz_c;
2905        int logfd, tz, reccnt = 0;
2906        struct stat st;
2907        unsigned long date;
2908        unsigned char logged_sha1[20];
2909        void *log_mapped;
2910        size_t mapsz;
2911
2912        logfile = git_path("logs/%s", refname);
2913        logfd = open(logfile, O_RDONLY, 0);
2914        if (logfd < 0)
2915                die_errno("Unable to read log '%s'", logfile);
2916        fstat(logfd, &st);
2917        if (!st.st_size)
2918                die("Log %s is empty.", logfile);
2919        mapsz = xsize_t(st.st_size);
2920        log_mapped = xmmap(NULL, mapsz, PROT_READ, MAP_PRIVATE, logfd, 0);
2921        logdata = log_mapped;
2922        close(logfd);
2923
2924        lastrec = NULL;
2925        rec = logend = logdata + st.st_size;
2926        while (logdata < rec) {
2927                reccnt++;
2928                if (logdata < rec && *(rec-1) == '\n')
2929                        rec--;
2930                lastgt = NULL;
2931                while (logdata < rec && *(rec-1) != '\n') {
2932                        rec--;
2933                        if (*rec == '>')
2934                                lastgt = rec;
2935                }
2936                if (!lastgt)
2937                        die("Log %s is corrupt.", logfile);
2938                date = strtoul(lastgt + 1, &tz_c, 10);
2939                if (date <= at_time || cnt == 0) {
2940                        tz = strtoul(tz_c, NULL, 10);
2941                        if (msg)
2942                                *msg = ref_msg(rec, logend);
2943                        if (cutoff_time)
2944                                *cutoff_time = date;
2945                        if (cutoff_tz)
2946                                *cutoff_tz = tz;
2947                        if (cutoff_cnt)
2948                                *cutoff_cnt = reccnt - 1;
2949                        if (lastrec) {
2950                                if (get_sha1_hex(lastrec, logged_sha1))
2951                                        die("Log %s is corrupt.", logfile);
2952                                if (get_sha1_hex(rec + 41, sha1))
2953                                        die("Log %s is corrupt.", logfile);
2954                                if (hashcmp(logged_sha1, sha1)) {
2955                                        warning("Log %s has gap after %s.",
2956                                                logfile, show_date(date, tz, DATE_RFC2822));
2957                                }
2958                        }
2959                        else if (date == at_time) {
2960                                if (get_sha1_hex(rec + 41, sha1))
2961                                        die("Log %s is corrupt.", logfile);
2962                        }
2963                        else {
2964                                if (get_sha1_hex(rec + 41, logged_sha1))
2965                                        die("Log %s is corrupt.", logfile);
2966                                if (hashcmp(logged_sha1, sha1)) {
2967                                        warning("Log %s unexpectedly ended on %s.",
2968                                                logfile, show_date(date, tz, DATE_RFC2822));
2969                                }
2970                        }
2971                        munmap(log_mapped, mapsz);
2972                        return 0;
2973                }
2974                lastrec = rec;
2975                if (cnt > 0)
2976                        cnt--;
2977        }
2978
2979        rec = logdata;
2980        while (rec < logend && *rec != '>' && *rec != '\n')
2981                rec++;
2982        if (rec == logend || *rec == '\n')
2983                die("Log %s is corrupt.", logfile);
2984        date = strtoul(rec + 1, &tz_c, 10);
2985        tz = strtoul(tz_c, NULL, 10);
2986        if (get_sha1_hex(logdata, sha1))
2987                die("Log %s is corrupt.", logfile);
2988        if (is_null_sha1(sha1)) {
2989                if (get_sha1_hex(logdata + 41, sha1))
2990                        die("Log %s is corrupt.", logfile);
2991        }
2992        if (msg)
2993                *msg = ref_msg(logdata, logend);
2994        munmap(log_mapped, mapsz);
2995
2996        if (cutoff_time)
2997                *cutoff_time = date;
2998        if (cutoff_tz)
2999                *cutoff_tz = tz;
3000        if (cutoff_cnt)
3001                *cutoff_cnt = reccnt;
3002        return 1;
3003}
3004
3005static int show_one_reflog_ent(struct strbuf *sb, each_reflog_ent_fn fn, void *cb_data)
3006{
3007        unsigned char osha1[20], nsha1[20];
3008        char *email_end, *message;
3009        unsigned long timestamp;
3010        int tz;
3011
3012        /* old SP new SP name <email> SP time TAB msg LF */
3013        if (sb->len < 83 || sb->buf[sb->len - 1] != '\n' ||
3014            get_sha1_hex(sb->buf, osha1) || sb->buf[40] != ' ' ||
3015            get_sha1_hex(sb->buf + 41, nsha1) || sb->buf[81] != ' ' ||
3016            !(email_end = strchr(sb->buf + 82, '>')) ||
3017            email_end[1] != ' ' ||
3018            !(timestamp = strtoul(email_end + 2, &message, 10)) ||
3019            !message || message[0] != ' ' ||
3020            (message[1] != '+' && message[1] != '-') ||
3021            !isdigit(message[2]) || !isdigit(message[3]) ||
3022            !isdigit(message[4]) || !isdigit(message[5]))
3023                return 0; /* corrupt? */
3024        email_end[1] = '\0';
3025        tz = strtol(message + 1, NULL, 10);
3026        if (message[6] != '\t')
3027                message += 6;
3028        else
3029                message += 7;
3030        return fn(osha1, nsha1, sb->buf + 82, timestamp, tz, message, cb_data);
3031}
3032
3033static char *find_beginning_of_line(char *bob, char *scan)
3034{
3035        while (bob < scan && *(--scan) != '\n')
3036                ; /* keep scanning backwards */
3037        /*
3038         * Return either beginning of the buffer, or LF at the end of
3039         * the previous line.
3040         */
3041        return scan;
3042}
3043
3044int for_each_reflog_ent_reverse(const char *refname, each_reflog_ent_fn fn, void *cb_data)
3045{
3046        struct strbuf sb = STRBUF_INIT;
3047        FILE *logfp;
3048        long pos;
3049        int ret = 0, at_tail = 1;
3050
3051        logfp = fopen(git_path("logs/%s", refname), "r");
3052        if (!logfp)
3053                return -1;
3054
3055        /* Jump to the end */
3056        if (fseek(logfp, 0, SEEK_END) < 0)
3057                return error("cannot seek back reflog for %s: %s",
3058                             refname, strerror(errno));
3059        pos = ftell(logfp);
3060        while (!ret && 0 < pos) {
3061                int cnt;
3062                size_t nread;
3063                char buf[BUFSIZ];
3064                char *endp, *scanp;
3065
3066                /* Fill next block from the end */
3067                cnt = (sizeof(buf) < pos) ? sizeof(buf) : pos;
3068                if (fseek(logfp, pos - cnt, SEEK_SET))
3069                        return error("cannot seek back reflog for %s: %s",
3070                                     refname, strerror(errno));
3071                nread = fread(buf, cnt, 1, logfp);
3072                if (nread != 1)
3073                        return error("cannot read %d bytes from reflog for %s: %s",
3074                                     cnt, refname, strerror(errno));
3075                pos -= cnt;
3076
3077                scanp = endp = buf + cnt;
3078                if (at_tail && scanp[-1] == '\n')
3079                        /* Looking at the final LF at the end of the file */
3080                        scanp--;
3081                at_tail = 0;
3082
3083                while (buf < scanp) {
3084                        /*
3085                         * terminating LF of the previous line, or the beginning
3086                         * of the buffer.
3087                         */
3088                        char *bp;
3089
3090                        bp = find_beginning_of_line(buf, scanp);
3091
3092                        if (*bp != '\n') {
3093                                strbuf_splice(&sb, 0, 0, buf, endp - buf);
3094                                if (pos)
3095                                        break; /* need to fill another block */
3096                                scanp = buf - 1; /* leave loop */
3097                        } else {
3098                                /*
3099                                 * (bp + 1) thru endp is the beginning of the
3100                                 * current line we have in sb
3101                                 */
3102                                strbuf_splice(&sb, 0, 0, bp + 1, endp - (bp + 1));
3103                                scanp = bp;
3104                                endp = bp + 1;
3105                        }
3106                        ret = show_one_reflog_ent(&sb, fn, cb_data);
3107                        strbuf_reset(&sb);
3108                        if (ret)
3109                                break;
3110                }
3111
3112        }
3113        if (!ret && sb.len)
3114                ret = show_one_reflog_ent(&sb, fn, cb_data);
3115
3116        fclose(logfp);
3117        strbuf_release(&sb);
3118        return ret;
3119}
3120
3121int for_each_reflog_ent(const char *refname, each_reflog_ent_fn fn, void *cb_data)
3122{
3123        FILE *logfp;
3124        struct strbuf sb = STRBUF_INIT;
3125        int ret = 0;
3126
3127        logfp = fopen(git_path("logs/%s", refname), "r");
3128        if (!logfp)
3129                return -1;
3130
3131        while (!ret && !strbuf_getwholeline(&sb, logfp, '\n'))
3132                ret = show_one_reflog_ent(&sb, fn, cb_data);
3133        fclose(logfp);
3134        strbuf_release(&sb);
3135        return ret;
3136}
3137/*
3138 * Call fn for each reflog in the namespace indicated by name.  name
3139 * must be empty or end with '/'.  Name will be used as a scratch
3140 * space, but its contents will be restored before return.
3141 */
3142static int do_for_each_reflog(struct strbuf *name, each_ref_fn fn, void *cb_data)
3143{
3144        DIR *d = opendir(git_path("logs/%s", name->buf));
3145        int retval = 0;
3146        struct dirent *de;
3147        int oldlen = name->len;
3148
3149        if (!d)
3150                return name->len ? errno : 0;
3151
3152        while ((de = readdir(d)) != NULL) {
3153                struct stat st;
3154
3155                if (de->d_name[0] == '.')
3156                        continue;
3157                if (has_extension(de->d_name, ".lock"))
3158                        continue;
3159                strbuf_addstr(name, de->d_name);
3160                if (stat(git_path("logs/%s", name->buf), &st) < 0) {
3161                        ; /* silently ignore */
3162                } else {
3163                        if (S_ISDIR(st.st_mode)) {
3164                                strbuf_addch(name, '/');
3165                                retval = do_for_each_reflog(name, fn, cb_data);
3166                        } else {
3167                                unsigned char sha1[20];
3168                                if (read_ref_full(name->buf, sha1, 0, NULL))
3169                                        retval = error("bad ref for %s", name->buf);
3170                                else
3171                                        retval = fn(name->buf, sha1, 0, cb_data);
3172                        }
3173                        if (retval)
3174                                break;
3175                }
3176                strbuf_setlen(name, oldlen);
3177        }
3178        closedir(d);
3179        return retval;
3180}
3181
3182int for_each_reflog(each_ref_fn fn, void *cb_data)
3183{
3184        int retval;
3185        struct strbuf name;
3186        strbuf_init(&name, PATH_MAX);
3187        retval = do_for_each_reflog(&name, fn, cb_data);
3188        strbuf_release(&name);
3189        return retval;
3190}
3191
3192static struct ref_lock *update_ref_lock(const char *refname,
3193                                        const unsigned char *oldval,
3194                                        int flags, int *type_p,
3195                                        enum action_on_err onerr)
3196{
3197        struct ref_lock *lock;
3198        lock = lock_any_ref_for_update(refname, oldval, flags, type_p);
3199        if (!lock) {
3200                const char *str = "Cannot lock the ref '%s'.";
3201                switch (onerr) {
3202                case MSG_ON_ERR: error(str, refname); break;
3203                case DIE_ON_ERR: die(str, refname); break;
3204                case QUIET_ON_ERR: break;
3205                }
3206        }
3207        return lock;
3208}
3209
3210static int update_ref_write(const char *action, const char *refname,
3211                            const unsigned char *sha1, struct ref_lock *lock,
3212                            enum action_on_err onerr)
3213{
3214        if (write_ref_sha1(lock, sha1, action) < 0) {
3215                const char *str = "Cannot update the ref '%s'.";
3216                switch (onerr) {
3217                case MSG_ON_ERR: error(str, refname); break;
3218                case DIE_ON_ERR: die(str, refname); break;
3219                case QUIET_ON_ERR: break;
3220                }
3221                return 1;
3222        }
3223        return 0;
3224}
3225
3226int update_ref(const char *action, const char *refname,
3227               const unsigned char *sha1, const unsigned char *oldval,
3228               int flags, enum action_on_err onerr)
3229{
3230        struct ref_lock *lock;
3231        lock = update_ref_lock(refname, oldval, flags, NULL, onerr);
3232        if (!lock)
3233                return 1;
3234        return update_ref_write(action, refname, sha1, lock, onerr);
3235}
3236
3237static int ref_update_compare(const void *r1, const void *r2)
3238{
3239        const struct ref_update * const *u1 = r1;
3240        const struct ref_update * const *u2 = r2;
3241        return strcmp((*u1)->ref_name, (*u2)->ref_name);
3242}
3243
3244static int ref_update_reject_duplicates(struct ref_update **updates, int n,
3245                                        enum action_on_err onerr)
3246{
3247        int i;
3248        for (i = 1; i < n; i++)
3249                if (!strcmp(updates[i - 1]->ref_name, updates[i]->ref_name)) {
3250                        const char *str =
3251                                "Multiple updates for ref '%s' not allowed.";
3252                        switch (onerr) {
3253                        case MSG_ON_ERR:
3254                                error(str, updates[i]->ref_name); break;
3255                        case DIE_ON_ERR:
3256                                die(str, updates[i]->ref_name); break;
3257                        case QUIET_ON_ERR:
3258                                break;
3259                        }
3260                        return 1;
3261                }
3262        return 0;
3263}
3264
3265int update_refs(const char *action, const struct ref_update **updates_orig,
3266                int n, enum action_on_err onerr)
3267{
3268        int ret = 0, delnum = 0, i;
3269        struct ref_update **updates;
3270        int *types;
3271        struct ref_lock **locks;
3272        const char **delnames;
3273
3274        if (!updates_orig || !n)
3275                return 0;
3276
3277        /* Allocate work space */
3278        updates = xmalloc(sizeof(*updates) * n);
3279        types = xmalloc(sizeof(*types) * n);
3280        locks = xcalloc(n, sizeof(*locks));
3281        delnames = xmalloc(sizeof(*delnames) * n);
3282
3283        /* Copy, sort, and reject duplicate refs */
3284        memcpy(updates, updates_orig, sizeof(*updates) * n);
3285        qsort(updates, n, sizeof(*updates), ref_update_compare);
3286        ret = ref_update_reject_duplicates(updates, n, onerr);
3287        if (ret)
3288                goto cleanup;
3289
3290        /* Acquire all locks while verifying old values */
3291        for (i = 0; i < n; i++) {
3292                locks[i] = update_ref_lock(updates[i]->ref_name,
3293                                           (updates[i]->have_old ?
3294                                            updates[i]->old_sha1 : NULL),
3295                                           updates[i]->flags,
3296                                           &types[i], onerr);
3297                if (!locks[i]) {
3298                        ret = 1;
3299                        goto cleanup;
3300                }
3301        }
3302
3303        /* Perform updates first so live commits remain referenced */
3304        for (i = 0; i < n; i++)
3305                if (!is_null_sha1(updates[i]->new_sha1)) {
3306                        ret = update_ref_write(action,
3307                                               updates[i]->ref_name,
3308                                               updates[i]->new_sha1,
3309                                               locks[i], onerr);
3310                        locks[i] = NULL; /* freed by update_ref_write */
3311                        if (ret)
3312                                goto cleanup;
3313                }
3314
3315        /* Perform deletes now that updates are safely completed */
3316        for (i = 0; i < n; i++)
3317                if (locks[i]) {
3318                        delnames[delnum++] = locks[i]->ref_name;
3319                        ret |= delete_ref_loose(locks[i], types[i]);
3320                }
3321        ret |= repack_without_refs(delnames, delnum);
3322        for (i = 0; i < delnum; i++)
3323                unlink_or_warn(git_path("logs/%s", delnames[i]));
3324        clear_loose_ref_cache(&ref_cache);
3325
3326cleanup:
3327        for (i = 0; i < n; i++)
3328                if (locks[i])
3329                        unlock_ref(locks[i]);
3330        free(updates);
3331        free(types);
3332        free(locks);
3333        free(delnames);
3334        return ret;
3335}
3336
3337char *shorten_unambiguous_ref(const char *refname, int strict)
3338{
3339        int i;
3340        static char **scanf_fmts;
3341        static int nr_rules;
3342        char *short_name;
3343
3344        if (!nr_rules) {
3345                /*
3346                 * Pre-generate scanf formats from ref_rev_parse_rules[].
3347                 * Generate a format suitable for scanf from a
3348                 * ref_rev_parse_rules rule by interpolating "%s" at the
3349                 * location of the "%.*s".
3350                 */
3351                size_t total_len = 0;
3352                size_t offset = 0;
3353
3354                /* the rule list is NULL terminated, count them first */
3355                for (nr_rules = 0; ref_rev_parse_rules[nr_rules]; nr_rules++)
3356                        /* -2 for strlen("%.*s") - strlen("%s"); +1 for NUL */
3357                        total_len += strlen(ref_rev_parse_rules[nr_rules]) - 2 + 1;
3358
3359                scanf_fmts = xmalloc(nr_rules * sizeof(char *) + total_len);
3360
3361                offset = 0;
3362                for (i = 0; i < nr_rules; i++) {
3363                        assert(offset < total_len);
3364                        scanf_fmts[i] = (char *)&scanf_fmts[nr_rules] + offset;
3365                        offset += snprintf(scanf_fmts[i], total_len - offset,
3366                                           ref_rev_parse_rules[i], 2, "%s") + 1;
3367                }
3368        }
3369
3370        /* bail out if there are no rules */
3371        if (!nr_rules)
3372                return xstrdup(refname);
3373
3374        /* buffer for scanf result, at most refname must fit */
3375        short_name = xstrdup(refname);
3376
3377        /* skip first rule, it will always match */
3378        for (i = nr_rules - 1; i > 0 ; --i) {
3379                int j;
3380                int rules_to_fail = i;
3381                int short_name_len;
3382
3383                if (1 != sscanf(refname, scanf_fmts[i], short_name))
3384                        continue;
3385
3386                short_name_len = strlen(short_name);
3387
3388                /*
3389                 * in strict mode, all (except the matched one) rules
3390                 * must fail to resolve to a valid non-ambiguous ref
3391                 */
3392                if (strict)
3393                        rules_to_fail = nr_rules;
3394
3395                /*
3396                 * check if the short name resolves to a valid ref,
3397                 * but use only rules prior to the matched one
3398                 */
3399                for (j = 0; j < rules_to_fail; j++) {
3400                        const char *rule = ref_rev_parse_rules[j];
3401                        char refname[PATH_MAX];
3402
3403                        /* skip matched rule */
3404                        if (i == j)
3405                                continue;
3406
3407                        /*
3408                         * the short name is ambiguous, if it resolves
3409                         * (with this previous rule) to a valid ref
3410                         * read_ref() returns 0 on success
3411                         */
3412                        mksnpath(refname, sizeof(refname),
3413                                 rule, short_name_len, short_name);
3414                        if (ref_exists(refname))
3415                                break;
3416                }
3417
3418                /*
3419                 * short name is non-ambiguous if all previous rules
3420                 * haven't resolved to a valid ref
3421                 */
3422                if (j == rules_to_fail)
3423                        return short_name;
3424        }
3425
3426        free(short_name);
3427        return xstrdup(refname);
3428}
3429
3430static struct string_list *hide_refs;
3431
3432int parse_hide_refs_config(const char *var, const char *value, const char *section)
3433{
3434        if (!strcmp("transfer.hiderefs", var) ||
3435            /* NEEDSWORK: use parse_config_key() once both are merged */
3436            (starts_with(var, section) && var[strlen(section)] == '.' &&
3437             !strcmp(var + strlen(section), ".hiderefs"))) {
3438                char *ref;
3439                int len;
3440
3441                if (!value)
3442                        return config_error_nonbool(var);
3443                ref = xstrdup(value);
3444                len = strlen(ref);
3445                while (len && ref[len - 1] == '/')
3446                        ref[--len] = '\0';
3447                if (!hide_refs) {
3448                        hide_refs = xcalloc(1, sizeof(*hide_refs));
3449                        hide_refs->strdup_strings = 1;
3450                }
3451                string_list_append(hide_refs, ref);
3452        }
3453        return 0;
3454}
3455
3456int ref_is_hidden(const char *refname)
3457{
3458        struct string_list_item *item;
3459
3460        if (!hide_refs)
3461                return 0;
3462        for_each_string_list_item(item, hide_refs) {
3463                int len;
3464                if (!starts_with(refname, item->string))
3465                        continue;
3466                len = strlen(item->string);
3467                if (!refname[len] || refname[len] == '/')
3468                        return 1;
3469        }
3470        return 0;
3471}