8c39bd76e5c9044ca867c91898b208eb82028f17
   1#include "cache.h"
   2#include "refs.h"
   3#include "object.h"
   4#include "tag.h"
   5#include "dir.h"
   6
   7/*
   8 * Make sure "ref" is something reasonable to have under ".git/refs/";
   9 * We do not like it if:
  10 *
  11 * - any path component of it begins with ".", or
  12 * - it has double dots "..", or
  13 * - it has ASCII control character, "~", "^", ":" or SP, anywhere, or
  14 * - it ends with a "/".
  15 * - it ends with ".lock"
  16 * - it contains a "\" (backslash)
  17 */
  18
  19/* Return true iff ch is not allowed in reference names. */
  20static inline int bad_ref_char(int ch)
  21{
  22        if (((unsigned) ch) <= ' ' || ch == 0x7f ||
  23            ch == '~' || ch == '^' || ch == ':' || ch == '\\')
  24                return 1;
  25        /* 2.13 Pattern Matching Notation */
  26        if (ch == '*' || ch == '?' || ch == '[') /* Unsupported */
  27                return 1;
  28        return 0;
  29}
  30
  31/*
  32 * Try to read one refname component from the front of refname.  Return
  33 * the length of the component found, or -1 if the component is not
  34 * legal.
  35 */
  36static int check_refname_component(const char *refname, int flags)
  37{
  38        const char *cp;
  39        char last = '\0';
  40
  41        for (cp = refname; ; cp++) {
  42                char ch = *cp;
  43                if (ch == '\0' || ch == '/')
  44                        break;
  45                if (bad_ref_char(ch))
  46                        return -1; /* Illegal character in refname. */
  47                if (last == '.' && ch == '.')
  48                        return -1; /* Refname contains "..". */
  49                if (last == '@' && ch == '{')
  50                        return -1; /* Refname contains "@{". */
  51                last = ch;
  52        }
  53        if (cp == refname)
  54                return 0; /* Component has zero length. */
  55        if (refname[0] == '.') {
  56                if (!(flags & REFNAME_DOT_COMPONENT))
  57                        return -1; /* Component starts with '.'. */
  58                /*
  59                 * Even if leading dots are allowed, don't allow "."
  60                 * as a component (".." is prevented by a rule above).
  61                 */
  62                if (refname[1] == '\0')
  63                        return -1; /* Component equals ".". */
  64        }
  65        if (cp - refname >= 5 && !memcmp(cp - 5, ".lock", 5))
  66                return -1; /* Refname ends with ".lock". */
  67        return cp - refname;
  68}
  69
  70int check_refname_format(const char *refname, int flags)
  71{
  72        int component_len, component_count = 0;
  73
  74        while (1) {
  75                /* We are at the start of a path component. */
  76                component_len = check_refname_component(refname, flags);
  77                if (component_len <= 0) {
  78                        if ((flags & REFNAME_REFSPEC_PATTERN) &&
  79                                        refname[0] == '*' &&
  80                                        (refname[1] == '\0' || refname[1] == '/')) {
  81                                /* Accept one wildcard as a full refname component. */
  82                                flags &= ~REFNAME_REFSPEC_PATTERN;
  83                                component_len = 1;
  84                        } else {
  85                                return -1;
  86                        }
  87                }
  88                component_count++;
  89                if (refname[component_len] == '\0')
  90                        break;
  91                /* Skip to next component. */
  92                refname += component_len + 1;
  93        }
  94
  95        if (refname[component_len - 1] == '.')
  96                return -1; /* Refname ends with '.'. */
  97        if (!(flags & REFNAME_ALLOW_ONELEVEL) && component_count < 2)
  98                return -1; /* Refname has only one component. */
  99        return 0;
 100}
 101
 102struct ref_entry;
 103
 104struct ref_value {
 105        unsigned char sha1[20];
 106        unsigned char peeled[20];
 107};
 108
 109struct ref_dir {
 110        int nr, alloc;
 111
 112        /*
 113         * Entries with index 0 <= i < sorted are sorted by name.  New
 114         * entries are appended to the list unsorted, and are sorted
 115         * only when required; thus we avoid the need to sort the list
 116         * after the addition of every reference.
 117         */
 118        int sorted;
 119
 120        struct ref_entry **entries;
 121};
 122
 123/* ISSYMREF=0x01, ISPACKED=0x02, and ISBROKEN=0x04 are public interfaces */
 124#define REF_KNOWS_PEELED 0x08
 125#define REF_DIR 0x10
 126
 127/*
 128 * A ref_entry represents either a reference or a "subdirectory" of
 129 * references.  Each directory in the reference namespace is
 130 * represented by a ref_entry with (flags & REF_DIR) set and
 131 * containing a subdir member that holds the entries in that
 132 * directory.  References are represented by a ref_entry with (flags &
 133 * REF_DIR) unset and a value member that describes the reference's
 134 * value.  The flag member is at the ref_entry level, but it is also
 135 * needed to interpret the contents of the value field (in other
 136 * words, a ref_value object is not very much use without the
 137 * enclosing ref_entry).
 138 *
 139 * Reference names cannot end with slash and directories' names are
 140 * always stored with a trailing slash (except for the top-level
 141 * directory, which is always denoted by "").  This has two nice
 142 * consequences: (1) when the entries in each subdir are sorted
 143 * lexicographically by name (as they usually are), the references in
 144 * a whole tree can be generated in lexicographic order by traversing
 145 * the tree in left-to-right, depth-first order; (2) the names of
 146 * references and subdirectories cannot conflict, and therefore the
 147 * presence of an empty subdirectory does not block the creation of a
 148 * similarly-named reference.  (The fact that reference names with the
 149 * same leading components can conflict *with each other* is a
 150 * separate issue that is regulated by is_refname_available().)
 151 *
 152 * Please note that the name field contains the fully-qualified
 153 * reference (or subdirectory) name.  Space could be saved by only
 154 * storing the relative names.  But that would require the full names
 155 * to be generated on the fly when iterating in do_for_each_ref(), and
 156 * would break callback functions, who have always been able to assume
 157 * that the name strings that they are passed will not be freed during
 158 * the iteration.
 159 */
 160struct ref_entry {
 161        unsigned char flag; /* ISSYMREF? ISPACKED? */
 162        union {
 163                struct ref_value value; /* if not (flags&REF_DIR) */
 164                struct ref_dir subdir; /* if (flags&REF_DIR) */
 165        } u;
 166        /*
 167         * The full name of the reference (e.g., "refs/heads/master")
 168         * or the full name of the directory with a trailing slash
 169         * (e.g., "refs/heads/"):
 170         */
 171        char name[FLEX_ARRAY];
 172};
 173
 174static struct ref_entry *create_ref_entry(const char *refname,
 175                                          const unsigned char *sha1, int flag,
 176                                          int check_name)
 177{
 178        int len;
 179        struct ref_entry *ref;
 180
 181        if (check_name &&
 182            check_refname_format(refname, REFNAME_ALLOW_ONELEVEL|REFNAME_DOT_COMPONENT))
 183                die("Reference has invalid format: '%s'", refname);
 184        len = strlen(refname) + 1;
 185        ref = xmalloc(sizeof(struct ref_entry) + len);
 186        hashcpy(ref->u.value.sha1, sha1);
 187        hashclr(ref->u.value.peeled);
 188        memcpy(ref->name, refname, len);
 189        ref->flag = flag;
 190        return ref;
 191}
 192
 193static void clear_ref_dir(struct ref_dir *dir);
 194
 195static void free_ref_entry(struct ref_entry *entry)
 196{
 197        if (entry->flag & REF_DIR)
 198                clear_ref_dir(&entry->u.subdir);
 199        free(entry);
 200}
 201
 202/*
 203 * Add a ref_entry to the end of dir (unsorted).  Entry is always
 204 * stored directly in dir; no recursion into subdirectories is
 205 * done.
 206 */
 207static void add_entry_to_dir(struct ref_dir *dir, struct ref_entry *entry)
 208{
 209        ALLOC_GROW(dir->entries, dir->nr + 1, dir->alloc);
 210        dir->entries[dir->nr++] = entry;
 211}
 212
 213/*
 214 * Clear and free all entries in dir, recursively.
 215 */
 216static void clear_ref_dir(struct ref_dir *dir)
 217{
 218        int i;
 219        for (i = 0; i < dir->nr; i++)
 220                free_ref_entry(dir->entries[i]);
 221        free(dir->entries);
 222        dir->sorted = dir->nr = dir->alloc = 0;
 223        dir->entries = NULL;
 224}
 225
 226/*
 227 * Create a struct ref_entry object for the specified dirname.
 228 * dirname is the name of the directory with a trailing slash (e.g.,
 229 * "refs/heads/") or "" for the top-level directory.
 230 */
 231static struct ref_entry *create_dir_entry(const char *dirname)
 232{
 233        struct ref_entry *direntry;
 234        int len = strlen(dirname);
 235        direntry = xcalloc(1, sizeof(struct ref_entry) + len + 1);
 236        memcpy(direntry->name, dirname, len + 1);
 237        direntry->flag = REF_DIR;
 238        return direntry;
 239}
 240
 241static int ref_entry_cmp(const void *a, const void *b)
 242{
 243        struct ref_entry *one = *(struct ref_entry **)a;
 244        struct ref_entry *two = *(struct ref_entry **)b;
 245        return strcmp(one->name, two->name);
 246}
 247
 248static void sort_ref_dir(struct ref_dir *dir);
 249
 250/*
 251 * Return the entry with the given refname from the ref_dir
 252 * (non-recursively), sorting dir if necessary.  Return NULL if no
 253 * such entry is found.
 254 */
 255static struct ref_entry *search_ref_dir(struct ref_dir *dir, const char *refname)
 256{
 257        struct ref_entry *e, **r;
 258        int len;
 259
 260        if (refname == NULL || !dir->nr)
 261                return NULL;
 262
 263        sort_ref_dir(dir);
 264
 265        len = strlen(refname) + 1;
 266        e = xmalloc(sizeof(struct ref_entry) + len);
 267        memcpy(e->name, refname, len);
 268
 269        r = bsearch(&e, dir->entries, dir->nr, sizeof(*dir->entries), ref_entry_cmp);
 270
 271        free(e);
 272
 273        if (r == NULL)
 274                return NULL;
 275
 276        return *r;
 277}
 278
 279/*
 280 * Search for a directory entry directly within dir (without
 281 * recursing).  Sort dir if necessary.  subdirname must be a directory
 282 * name (i.e., end in '/').  If mkdir is set, then create the
 283 * directory if it is missing; otherwise, return NULL if the desired
 284 * directory cannot be found.
 285 */
 286static struct ref_entry *search_for_subdir(struct ref_dir *dir,
 287                                           const char *subdirname, int mkdir)
 288{
 289        struct ref_entry *entry = search_ref_dir(dir, subdirname);
 290        if (!entry) {
 291                if (!mkdir)
 292                        return NULL;
 293                entry = create_dir_entry(subdirname);
 294                add_entry_to_dir(dir, entry);
 295        }
 296        assert(entry->flag & REF_DIR);
 297        return entry;
 298}
 299
 300/*
 301 * If refname is a reference name, find the ref_dir within the dir
 302 * tree that should hold refname.  If refname is a directory name
 303 * (i.e., ends in '/'), then return that ref_dir itself.  dir must
 304 * represent the top-level directory.  Sort ref_dirs and recurse into
 305 * subdirectories as necessary.  If mkdir is set, then create any
 306 * missing directories; otherwise, return NULL if the desired
 307 * directory cannot be found.
 308 */
 309static struct ref_dir *find_containing_dir(struct ref_dir *dir,
 310                                           const char *refname, int mkdir)
 311{
 312        char *refname_copy = xstrdup(refname);
 313        char *slash;
 314        struct ref_entry *entry;
 315        for (slash = strchr(refname_copy, '/'); slash; slash = strchr(slash + 1, '/')) {
 316                char tmp = slash[1];
 317                slash[1] = '\0';
 318                entry = search_for_subdir(dir, refname_copy, mkdir);
 319                slash[1] = tmp;
 320                if (!entry)
 321                        break;
 322                dir = &entry->u.subdir;
 323        }
 324
 325        free(refname_copy);
 326        return dir;
 327}
 328
 329/*
 330 * Find the value entry with the given name in dir, sorting ref_dirs
 331 * and recursing into subdirectories as necessary.  If the name is not
 332 * found or it corresponds to a directory entry, return NULL.
 333 */
 334static struct ref_entry *find_ref(struct ref_dir *dir, const char *refname)
 335{
 336        struct ref_entry *entry;
 337        dir = find_containing_dir(dir, refname, 0);
 338        if (!dir)
 339                return NULL;
 340        entry = search_ref_dir(dir, refname);
 341        return (entry && !(entry->flag & REF_DIR)) ? entry : NULL;
 342}
 343
 344/*
 345 * Add a ref_entry to the ref_dir (unsorted), recursing into
 346 * subdirectories as necessary.  dir must represent the top-level
 347 * directory.  Return 0 on success.
 348 */
 349static int add_ref(struct ref_dir *dir, struct ref_entry *ref)
 350{
 351        dir = find_containing_dir(dir, ref->name, 1);
 352        if (!dir)
 353                return -1;
 354        add_entry_to_dir(dir, ref);
 355        return 0;
 356}
 357
 358/*
 359 * Emit a warning and return true iff ref1 and ref2 have the same name
 360 * and the same sha1.  Die if they have the same name but different
 361 * sha1s.
 362 */
 363static int is_dup_ref(const struct ref_entry *ref1, const struct ref_entry *ref2)
 364{
 365        if (strcmp(ref1->name, ref2->name))
 366                return 0;
 367
 368        /* Duplicate name; make sure that they don't conflict: */
 369
 370        if ((ref1->flag & REF_DIR) || (ref2->flag & REF_DIR))
 371                /* This is impossible by construction */
 372                die("Reference directory conflict: %s", ref1->name);
 373
 374        if (hashcmp(ref1->u.value.sha1, ref2->u.value.sha1))
 375                die("Duplicated ref, and SHA1s don't match: %s", ref1->name);
 376
 377        warning("Duplicated ref: %s", ref1->name);
 378        return 1;
 379}
 380
 381/*
 382 * Sort the entries in dir non-recursively (if they are not already
 383 * sorted) and remove any duplicate entries.
 384 */
 385static void sort_ref_dir(struct ref_dir *dir)
 386{
 387        int i, j;
 388        struct ref_entry *last = NULL;
 389
 390        /*
 391         * This check also prevents passing a zero-length array to qsort(),
 392         * which is a problem on some platforms.
 393         */
 394        if (dir->sorted == dir->nr)
 395                return;
 396
 397        qsort(dir->entries, dir->nr, sizeof(*dir->entries), ref_entry_cmp);
 398
 399        /* Remove any duplicates: */
 400        for (i = 0, j = 0; j < dir->nr; j++) {
 401                struct ref_entry *entry = dir->entries[j];
 402                if (last && is_dup_ref(last, entry))
 403                        free_ref_entry(entry);
 404                else
 405                        last = dir->entries[i++] = entry;
 406        }
 407        dir->sorted = dir->nr = i;
 408}
 409
 410#define DO_FOR_EACH_INCLUDE_BROKEN 01
 411
 412static struct ref_entry *current_ref;
 413
 414static int do_one_ref(const char *base, each_ref_fn fn, int trim,
 415                      int flags, void *cb_data, struct ref_entry *entry)
 416{
 417        int retval;
 418        if (prefixcmp(entry->name, base))
 419                return 0;
 420
 421        if (!(flags & DO_FOR_EACH_INCLUDE_BROKEN)) {
 422                if (entry->flag & REF_ISBROKEN)
 423                        return 0; /* ignore broken refs e.g. dangling symref */
 424                if (!has_sha1_file(entry->u.value.sha1)) {
 425                        error("%s does not point to a valid object!", entry->name);
 426                        return 0;
 427                }
 428        }
 429        current_ref = entry;
 430        retval = fn(entry->name + trim, entry->u.value.sha1, entry->flag, cb_data);
 431        current_ref = NULL;
 432        return retval;
 433}
 434
 435/*
 436 * Call fn for each reference in dir that has index in the range
 437 * offset <= index < dir->nr.  Recurse into subdirectories that are in
 438 * that index range, sorting them before iterating.  This function
 439 * does not sort dir itself; it should be sorted beforehand.
 440 */
 441static int do_for_each_ref_in_dir(struct ref_dir *dir, int offset,
 442                                  const char *base,
 443                                  each_ref_fn fn, int trim, int flags, void *cb_data)
 444{
 445        int i;
 446        assert(dir->sorted == dir->nr);
 447        for (i = offset; i < dir->nr; i++) {
 448                struct ref_entry *entry = dir->entries[i];
 449                int retval;
 450                if (entry->flag & REF_DIR) {
 451                        sort_ref_dir(&entry->u.subdir);
 452                        retval = do_for_each_ref_in_dir(&entry->u.subdir, 0,
 453                                                        base, fn, trim, flags, cb_data);
 454                } else {
 455                        retval = do_one_ref(base, fn, trim, flags, cb_data, entry);
 456                }
 457                if (retval)
 458                        return retval;
 459        }
 460        return 0;
 461}
 462
 463/*
 464 * Call fn for each reference in the union of dir1 and dir2, in order
 465 * by refname.  Recurse into subdirectories.  If a value entry appears
 466 * in both dir1 and dir2, then only process the version that is in
 467 * dir2.  The input dirs must already be sorted, but subdirs will be
 468 * sorted as needed.
 469 */
 470static int do_for_each_ref_in_dirs(struct ref_dir *dir1,
 471                                   struct ref_dir *dir2,
 472                                   const char *base, each_ref_fn fn, int trim,
 473                                   int flags, void *cb_data)
 474{
 475        int retval;
 476        int i1 = 0, i2 = 0;
 477
 478        assert(dir1->sorted == dir1->nr);
 479        assert(dir2->sorted == dir2->nr);
 480        while (1) {
 481                struct ref_entry *e1, *e2;
 482                int cmp;
 483                if (i1 == dir1->nr) {
 484                        return do_for_each_ref_in_dir(dir2, i2,
 485                                                      base, fn, trim, flags, cb_data);
 486                }
 487                if (i2 == dir2->nr) {
 488                        return do_for_each_ref_in_dir(dir1, i1,
 489                                                      base, fn, trim, flags, cb_data);
 490                }
 491                e1 = dir1->entries[i1];
 492                e2 = dir2->entries[i2];
 493                cmp = strcmp(e1->name, e2->name);
 494                if (cmp == 0) {
 495                        if ((e1->flag & REF_DIR) && (e2->flag & REF_DIR)) {
 496                                /* Both are directories; descend them in parallel. */
 497                                sort_ref_dir(&e1->u.subdir);
 498                                sort_ref_dir(&e2->u.subdir);
 499                                retval = do_for_each_ref_in_dirs(
 500                                                &e1->u.subdir, &e2->u.subdir,
 501                                                base, fn, trim, flags, cb_data);
 502                                i1++;
 503                                i2++;
 504                        } else if (!(e1->flag & REF_DIR) && !(e2->flag & REF_DIR)) {
 505                                /* Both are references; ignore the one from dir1. */
 506                                retval = do_one_ref(base, fn, trim, flags, cb_data, e2);
 507                                i1++;
 508                                i2++;
 509                        } else {
 510                                die("conflict between reference and directory: %s",
 511                                    e1->name);
 512                        }
 513                } else {
 514                        struct ref_entry *e;
 515                        if (cmp < 0) {
 516                                e = e1;
 517                                i1++;
 518                        } else {
 519                                e = e2;
 520                                i2++;
 521                        }
 522                        if (e->flag & REF_DIR) {
 523                                sort_ref_dir(&e->u.subdir);
 524                                retval = do_for_each_ref_in_dir(
 525                                                &e->u.subdir, 0,
 526                                                base, fn, trim, flags, cb_data);
 527                        } else {
 528                                retval = do_one_ref(base, fn, trim, flags, cb_data, e);
 529                        }
 530                }
 531                if (retval)
 532                        return retval;
 533        }
 534        if (i1 < dir1->nr)
 535                return do_for_each_ref_in_dir(dir1, i1,
 536                                              base, fn, trim, flags, cb_data);
 537        if (i2 < dir2->nr)
 538                return do_for_each_ref_in_dir(dir2, i2,
 539                                              base, fn, trim, flags, cb_data);
 540        return 0;
 541}
 542
 543/*
 544 * Return true iff refname1 and refname2 conflict with each other.
 545 * Two reference names conflict if one of them exactly matches the
 546 * leading components of the other; e.g., "foo/bar" conflicts with
 547 * both "foo" and with "foo/bar/baz" but not with "foo/bar" or
 548 * "foo/barbados".
 549 */
 550static int names_conflict(const char *refname1, const char *refname2)
 551{
 552        for (; *refname1 && *refname1 == *refname2; refname1++, refname2++)
 553                ;
 554        return (*refname1 == '\0' && *refname2 == '/')
 555                || (*refname1 == '/' && *refname2 == '\0');
 556}
 557
 558struct name_conflict_cb {
 559        const char *refname;
 560        const char *oldrefname;
 561        const char *conflicting_refname;
 562};
 563
 564static int name_conflict_fn(const char *existingrefname, const unsigned char *sha1,
 565                            int flags, void *cb_data)
 566{
 567        struct name_conflict_cb *data = (struct name_conflict_cb *)cb_data;
 568        if (data->oldrefname && !strcmp(data->oldrefname, existingrefname))
 569                return 0;
 570        if (names_conflict(data->refname, existingrefname)) {
 571                data->conflicting_refname = existingrefname;
 572                return 1;
 573        }
 574        return 0;
 575}
 576
 577/*
 578 * Return true iff a reference named refname could be created without
 579 * conflicting with the name of an existing reference in array.  If
 580 * oldrefname is non-NULL, ignore potential conflicts with oldrefname
 581 * (e.g., because oldrefname is scheduled for deletion in the same
 582 * operation).
 583 */
 584static int is_refname_available(const char *refname, const char *oldrefname,
 585                                struct ref_dir *dir)
 586{
 587        struct name_conflict_cb data;
 588        data.refname = refname;
 589        data.oldrefname = oldrefname;
 590        data.conflicting_refname = NULL;
 591
 592        sort_ref_dir(dir);
 593        if (do_for_each_ref_in_dir(dir, 0, "", name_conflict_fn,
 594                                   0, DO_FOR_EACH_INCLUDE_BROKEN,
 595                                   &data)) {
 596                error("'%s' exists; cannot create '%s'",
 597                      data.conflicting_refname, refname);
 598                return 0;
 599        }
 600        return 1;
 601}
 602
 603/*
 604 * Future: need to be in "struct repository"
 605 * when doing a full libification.
 606 */
 607static struct ref_cache {
 608        struct ref_cache *next;
 609        char did_loose;
 610        char did_packed;
 611        struct ref_dir loose;
 612        struct ref_dir packed;
 613        /* The submodule name, or "" for the main repo. */
 614        char name[FLEX_ARRAY];
 615} *ref_cache;
 616
 617static void clear_packed_ref_cache(struct ref_cache *refs)
 618{
 619        if (refs->did_packed)
 620                clear_ref_dir(&refs->packed);
 621        refs->did_packed = 0;
 622}
 623
 624static void clear_loose_ref_cache(struct ref_cache *refs)
 625{
 626        if (refs->did_loose)
 627                clear_ref_dir(&refs->loose);
 628        refs->did_loose = 0;
 629}
 630
 631static struct ref_cache *create_ref_cache(const char *submodule)
 632{
 633        int len;
 634        struct ref_cache *refs;
 635        if (!submodule)
 636                submodule = "";
 637        len = strlen(submodule) + 1;
 638        refs = xcalloc(1, sizeof(struct ref_cache) + len);
 639        memcpy(refs->name, submodule, len);
 640        return refs;
 641}
 642
 643/*
 644 * Return a pointer to a ref_cache for the specified submodule. For
 645 * the main repository, use submodule==NULL. The returned structure
 646 * will be allocated and initialized but not necessarily populated; it
 647 * should not be freed.
 648 */
 649static struct ref_cache *get_ref_cache(const char *submodule)
 650{
 651        struct ref_cache *refs = ref_cache;
 652        if (!submodule)
 653                submodule = "";
 654        while (refs) {
 655                if (!strcmp(submodule, refs->name))
 656                        return refs;
 657                refs = refs->next;
 658        }
 659
 660        refs = create_ref_cache(submodule);
 661        refs->next = ref_cache;
 662        ref_cache = refs;
 663        return refs;
 664}
 665
 666void invalidate_ref_cache(const char *submodule)
 667{
 668        struct ref_cache *refs = get_ref_cache(submodule);
 669        clear_packed_ref_cache(refs);
 670        clear_loose_ref_cache(refs);
 671}
 672
 673/*
 674 * Parse one line from a packed-refs file.  Write the SHA1 to sha1.
 675 * Return a pointer to the refname within the line (null-terminated),
 676 * or NULL if there was a problem.
 677 */
 678static const char *parse_ref_line(char *line, unsigned char *sha1)
 679{
 680        /*
 681         * 42: the answer to everything.
 682         *
 683         * In this case, it happens to be the answer to
 684         *  40 (length of sha1 hex representation)
 685         *  +1 (space in between hex and name)
 686         *  +1 (newline at the end of the line)
 687         */
 688        int len = strlen(line) - 42;
 689
 690        if (len <= 0)
 691                return NULL;
 692        if (get_sha1_hex(line, sha1) < 0)
 693                return NULL;
 694        if (!isspace(line[40]))
 695                return NULL;
 696        line += 41;
 697        if (isspace(*line))
 698                return NULL;
 699        if (line[len] != '\n')
 700                return NULL;
 701        line[len] = 0;
 702
 703        return line;
 704}
 705
 706static void read_packed_refs(FILE *f, struct ref_dir *dir)
 707{
 708        struct ref_entry *last = NULL;
 709        char refline[PATH_MAX];
 710        int flag = REF_ISPACKED;
 711
 712        while (fgets(refline, sizeof(refline), f)) {
 713                unsigned char sha1[20];
 714                const char *refname;
 715                static const char header[] = "# pack-refs with:";
 716
 717                if (!strncmp(refline, header, sizeof(header)-1)) {
 718                        const char *traits = refline + sizeof(header) - 1;
 719                        if (strstr(traits, " peeled "))
 720                                flag |= REF_KNOWS_PEELED;
 721                        /* perhaps other traits later as well */
 722                        continue;
 723                }
 724
 725                refname = parse_ref_line(refline, sha1);
 726                if (refname) {
 727                        last = create_ref_entry(refname, sha1, flag, 1);
 728                        add_ref(dir, last);
 729                        continue;
 730                }
 731                if (last &&
 732                    refline[0] == '^' &&
 733                    strlen(refline) == 42 &&
 734                    refline[41] == '\n' &&
 735                    !get_sha1_hex(refline + 1, sha1))
 736                        hashcpy(last->u.value.peeled, sha1);
 737        }
 738}
 739
 740static struct ref_dir *get_packed_refs(struct ref_cache *refs)
 741{
 742        if (!refs->did_packed) {
 743                const char *packed_refs_file;
 744                FILE *f;
 745
 746                if (*refs->name)
 747                        packed_refs_file = git_path_submodule(refs->name, "packed-refs");
 748                else
 749                        packed_refs_file = git_path("packed-refs");
 750                f = fopen(packed_refs_file, "r");
 751                if (f) {
 752                        read_packed_refs(f, &refs->packed);
 753                        fclose(f);
 754                }
 755                refs->did_packed = 1;
 756        }
 757        return &refs->packed;
 758}
 759
 760void add_packed_ref(const char *refname, const unsigned char *sha1)
 761{
 762        add_ref(get_packed_refs(get_ref_cache(NULL)),
 763                        create_ref_entry(refname, sha1, REF_ISPACKED, 1));
 764}
 765
 766/*
 767 * Read the loose references for refs from the namespace dirname.
 768 * dirname must end with '/'.  dir must be the directory entry
 769 * corresponding to dirname.
 770 */
 771static void get_ref_dir(struct ref_cache *refs, const char *dirname,
 772                        struct ref_dir *dir)
 773{
 774        DIR *d;
 775        const char *path;
 776        struct dirent *de;
 777        int dirnamelen = strlen(dirname);
 778        struct strbuf refname;
 779
 780        if (*refs->name)
 781                path = git_path_submodule(refs->name, "%s", dirname);
 782        else
 783                path = git_path("%s", dirname);
 784
 785        d = opendir(path);
 786        if (!d)
 787                return;
 788
 789        strbuf_init(&refname, dirnamelen + 257);
 790        strbuf_add(&refname, dirname, dirnamelen);
 791
 792        while ((de = readdir(d)) != NULL) {
 793                unsigned char sha1[20];
 794                struct stat st;
 795                int flag;
 796                const char *refdir;
 797
 798                if (de->d_name[0] == '.')
 799                        continue;
 800                if (has_extension(de->d_name, ".lock"))
 801                        continue;
 802                strbuf_addstr(&refname, de->d_name);
 803                refdir = *refs->name
 804                        ? git_path_submodule(refs->name, "%s", refname.buf)
 805                        : git_path("%s", refname.buf);
 806                if (stat(refdir, &st) < 0) {
 807                        ; /* silently ignore */
 808                } else if (S_ISDIR(st.st_mode)) {
 809                        strbuf_addch(&refname, '/');
 810                        get_ref_dir(refs, refname.buf,
 811                                    &search_for_subdir(dir, refname.buf, 1)->u.subdir);
 812                } else {
 813                        if (*refs->name) {
 814                                hashclr(sha1);
 815                                flag = 0;
 816                                if (resolve_gitlink_ref(refs->name, refname.buf, sha1) < 0) {
 817                                        hashclr(sha1);
 818                                        flag |= REF_ISBROKEN;
 819                                }
 820                        } else if (read_ref_full(refname.buf, sha1, 1, &flag)) {
 821                                hashclr(sha1);
 822                                flag |= REF_ISBROKEN;
 823                        }
 824                        add_entry_to_dir(dir,
 825                                         create_ref_entry(refname.buf, sha1, flag, 1));
 826                }
 827                strbuf_setlen(&refname, dirnamelen);
 828        }
 829        strbuf_release(&refname);
 830        closedir(d);
 831}
 832
 833static struct ref_dir *get_loose_refs(struct ref_cache *refs)
 834{
 835        if (!refs->did_loose) {
 836                get_ref_dir(refs, "refs/",
 837                            &search_for_subdir(&refs->loose, "refs/", 1)->u.subdir);
 838                refs->did_loose = 1;
 839        }
 840        return &refs->loose;
 841}
 842
 843/* We allow "recursive" symbolic refs. Only within reason, though */
 844#define MAXDEPTH 5
 845#define MAXREFLEN (1024)
 846
 847/*
 848 * Called by resolve_gitlink_ref_recursive() after it failed to read
 849 * from the loose refs in ref_cache refs. Find <refname> in the
 850 * packed-refs file for the submodule.
 851 */
 852static int resolve_gitlink_packed_ref(struct ref_cache *refs,
 853                                      const char *refname, unsigned char *sha1)
 854{
 855        struct ref_entry *ref;
 856        struct ref_dir *dir = get_packed_refs(refs);
 857
 858        ref = find_ref(dir, refname);
 859        if (ref == NULL)
 860                return -1;
 861
 862        memcpy(sha1, ref->u.value.sha1, 20);
 863        return 0;
 864}
 865
 866static int resolve_gitlink_ref_recursive(struct ref_cache *refs,
 867                                         const char *refname, unsigned char *sha1,
 868                                         int recursion)
 869{
 870        int fd, len;
 871        char buffer[128], *p;
 872        char *path;
 873
 874        if (recursion > MAXDEPTH || strlen(refname) > MAXREFLEN)
 875                return -1;
 876        path = *refs->name
 877                ? git_path_submodule(refs->name, "%s", refname)
 878                : git_path("%s", refname);
 879        fd = open(path, O_RDONLY);
 880        if (fd < 0)
 881                return resolve_gitlink_packed_ref(refs, refname, sha1);
 882
 883        len = read(fd, buffer, sizeof(buffer)-1);
 884        close(fd);
 885        if (len < 0)
 886                return -1;
 887        while (len && isspace(buffer[len-1]))
 888                len--;
 889        buffer[len] = 0;
 890
 891        /* Was it a detached head or an old-fashioned symlink? */
 892        if (!get_sha1_hex(buffer, sha1))
 893                return 0;
 894
 895        /* Symref? */
 896        if (strncmp(buffer, "ref:", 4))
 897                return -1;
 898        p = buffer + 4;
 899        while (isspace(*p))
 900                p++;
 901
 902        return resolve_gitlink_ref_recursive(refs, p, sha1, recursion+1);
 903}
 904
 905int resolve_gitlink_ref(const char *path, const char *refname, unsigned char *sha1)
 906{
 907        int len = strlen(path), retval;
 908        char *submodule;
 909        struct ref_cache *refs;
 910
 911        while (len && path[len-1] == '/')
 912                len--;
 913        if (!len)
 914                return -1;
 915        submodule = xstrndup(path, len);
 916        refs = get_ref_cache(submodule);
 917        free(submodule);
 918
 919        retval = resolve_gitlink_ref_recursive(refs, refname, sha1, 0);
 920        return retval;
 921}
 922
 923/*
 924 * Try to read ref from the packed references.  On success, set sha1
 925 * and return 0; otherwise, return -1.
 926 */
 927static int get_packed_ref(const char *refname, unsigned char *sha1)
 928{
 929        struct ref_dir *packed = get_packed_refs(get_ref_cache(NULL));
 930        struct ref_entry *entry = find_ref(packed, refname);
 931        if (entry) {
 932                hashcpy(sha1, entry->u.value.sha1);
 933                return 0;
 934        }
 935        return -1;
 936}
 937
 938const char *resolve_ref_unsafe(const char *refname, unsigned char *sha1, int reading, int *flag)
 939{
 940        int depth = MAXDEPTH;
 941        ssize_t len;
 942        char buffer[256];
 943        static char refname_buffer[256];
 944
 945        if (flag)
 946                *flag = 0;
 947
 948        if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL))
 949                return NULL;
 950
 951        for (;;) {
 952                char path[PATH_MAX];
 953                struct stat st;
 954                char *buf;
 955                int fd;
 956
 957                if (--depth < 0)
 958                        return NULL;
 959
 960                git_snpath(path, sizeof(path), "%s", refname);
 961
 962                if (lstat(path, &st) < 0) {
 963                        if (errno != ENOENT)
 964                                return NULL;
 965                        /*
 966                         * The loose reference file does not exist;
 967                         * check for a packed reference.
 968                         */
 969                        if (!get_packed_ref(refname, sha1)) {
 970                                if (flag)
 971                                        *flag |= REF_ISPACKED;
 972                                return refname;
 973                        }
 974                        /* The reference is not a packed reference, either. */
 975                        if (reading) {
 976                                return NULL;
 977                        } else {
 978                                hashclr(sha1);
 979                                return refname;
 980                        }
 981                }
 982
 983                /* Follow "normalized" - ie "refs/.." symlinks by hand */
 984                if (S_ISLNK(st.st_mode)) {
 985                        len = readlink(path, buffer, sizeof(buffer)-1);
 986                        if (len < 0)
 987                                return NULL;
 988                        buffer[len] = 0;
 989                        if (!prefixcmp(buffer, "refs/") &&
 990                                        !check_refname_format(buffer, 0)) {
 991                                strcpy(refname_buffer, buffer);
 992                                refname = refname_buffer;
 993                                if (flag)
 994                                        *flag |= REF_ISSYMREF;
 995                                continue;
 996                        }
 997                }
 998
 999                /* Is it a directory? */
1000                if (S_ISDIR(st.st_mode)) {
1001                        errno = EISDIR;
1002                        return NULL;
1003                }
1004
1005                /*
1006                 * Anything else, just open it and try to use it as
1007                 * a ref
1008                 */
1009                fd = open(path, O_RDONLY);
1010                if (fd < 0)
1011                        return NULL;
1012                len = read_in_full(fd, buffer, sizeof(buffer)-1);
1013                close(fd);
1014                if (len < 0)
1015                        return NULL;
1016                while (len && isspace(buffer[len-1]))
1017                        len--;
1018                buffer[len] = '\0';
1019
1020                /*
1021                 * Is it a symbolic ref?
1022                 */
1023                if (prefixcmp(buffer, "ref:"))
1024                        break;
1025                if (flag)
1026                        *flag |= REF_ISSYMREF;
1027                buf = buffer + 4;
1028                while (isspace(*buf))
1029                        buf++;
1030                if (check_refname_format(buf, REFNAME_ALLOW_ONELEVEL)) {
1031                        if (flag)
1032                                *flag |= REF_ISBROKEN;
1033                        return NULL;
1034                }
1035                refname = strcpy(refname_buffer, buf);
1036        }
1037        /* Please note that FETCH_HEAD has a second line containing other data. */
1038        if (get_sha1_hex(buffer, sha1) || (buffer[40] != '\0' && !isspace(buffer[40]))) {
1039                if (flag)
1040                        *flag |= REF_ISBROKEN;
1041                return NULL;
1042        }
1043        return refname;
1044}
1045
1046char *resolve_refdup(const char *ref, unsigned char *sha1, int reading, int *flag)
1047{
1048        const char *ret = resolve_ref_unsafe(ref, sha1, reading, flag);
1049        return ret ? xstrdup(ret) : NULL;
1050}
1051
1052/* The argument to filter_refs */
1053struct ref_filter {
1054        const char *pattern;
1055        each_ref_fn *fn;
1056        void *cb_data;
1057};
1058
1059int read_ref_full(const char *refname, unsigned char *sha1, int reading, int *flags)
1060{
1061        if (resolve_ref_unsafe(refname, sha1, reading, flags))
1062                return 0;
1063        return -1;
1064}
1065
1066int read_ref(const char *refname, unsigned char *sha1)
1067{
1068        return read_ref_full(refname, sha1, 1, NULL);
1069}
1070
1071int ref_exists(const char *refname)
1072{
1073        unsigned char sha1[20];
1074        return !!resolve_ref_unsafe(refname, sha1, 1, NULL);
1075}
1076
1077static int filter_refs(const char *refname, const unsigned char *sha1, int flags,
1078                       void *data)
1079{
1080        struct ref_filter *filter = (struct ref_filter *)data;
1081        if (fnmatch(filter->pattern, refname, 0))
1082                return 0;
1083        return filter->fn(refname, sha1, flags, filter->cb_data);
1084}
1085
1086int peel_ref(const char *refname, unsigned char *sha1)
1087{
1088        int flag;
1089        unsigned char base[20];
1090        struct object *o;
1091
1092        if (current_ref && (current_ref->name == refname
1093                || !strcmp(current_ref->name, refname))) {
1094                if (current_ref->flag & REF_KNOWS_PEELED) {
1095                        hashcpy(sha1, current_ref->u.value.peeled);
1096                        return 0;
1097                }
1098                hashcpy(base, current_ref->u.value.sha1);
1099                goto fallback;
1100        }
1101
1102        if (read_ref_full(refname, base, 1, &flag))
1103                return -1;
1104
1105        if ((flag & REF_ISPACKED)) {
1106                struct ref_dir *dir = get_packed_refs(get_ref_cache(NULL));
1107                struct ref_entry *r = find_ref(dir, refname);
1108
1109                if (r != NULL && r->flag & REF_KNOWS_PEELED) {
1110                        hashcpy(sha1, r->u.value.peeled);
1111                        return 0;
1112                }
1113        }
1114
1115fallback:
1116        o = parse_object(base);
1117        if (o && o->type == OBJ_TAG) {
1118                o = deref_tag(o, refname, 0);
1119                if (o) {
1120                        hashcpy(sha1, o->sha1);
1121                        return 0;
1122                }
1123        }
1124        return -1;
1125}
1126
1127struct warn_if_dangling_data {
1128        FILE *fp;
1129        const char *refname;
1130        const char *msg_fmt;
1131};
1132
1133static int warn_if_dangling_symref(const char *refname, const unsigned char *sha1,
1134                                   int flags, void *cb_data)
1135{
1136        struct warn_if_dangling_data *d = cb_data;
1137        const char *resolves_to;
1138        unsigned char junk[20];
1139
1140        if (!(flags & REF_ISSYMREF))
1141                return 0;
1142
1143        resolves_to = resolve_ref_unsafe(refname, junk, 0, NULL);
1144        if (!resolves_to || strcmp(resolves_to, d->refname))
1145                return 0;
1146
1147        fprintf(d->fp, d->msg_fmt, refname);
1148        return 0;
1149}
1150
1151void warn_dangling_symref(FILE *fp, const char *msg_fmt, const char *refname)
1152{
1153        struct warn_if_dangling_data data;
1154
1155        data.fp = fp;
1156        data.refname = refname;
1157        data.msg_fmt = msg_fmt;
1158        for_each_rawref(warn_if_dangling_symref, &data);
1159}
1160
1161static int do_for_each_ref(const char *submodule, const char *base, each_ref_fn fn,
1162                           int trim, int flags, void *cb_data)
1163{
1164        struct ref_cache *refs = get_ref_cache(submodule);
1165        struct ref_dir *packed_dir = get_packed_refs(refs);
1166        struct ref_dir *loose_dir = get_loose_refs(refs);
1167        int retval = 0;
1168
1169        if (base && *base) {
1170                packed_dir = find_containing_dir(packed_dir, base, 0);
1171                loose_dir = find_containing_dir(loose_dir, base, 0);
1172        }
1173
1174        if (packed_dir && loose_dir) {
1175                sort_ref_dir(packed_dir);
1176                sort_ref_dir(loose_dir);
1177                retval = do_for_each_ref_in_dirs(
1178                                packed_dir, loose_dir,
1179                                base, fn, trim, flags, cb_data);
1180        } else if (packed_dir) {
1181                sort_ref_dir(packed_dir);
1182                retval = do_for_each_ref_in_dir(
1183                                packed_dir, 0,
1184                                base, fn, trim, flags, cb_data);
1185        } else if (loose_dir) {
1186                sort_ref_dir(loose_dir);
1187                retval = do_for_each_ref_in_dir(
1188                                loose_dir, 0,
1189                                base, fn, trim, flags, cb_data);
1190        }
1191
1192        return retval;
1193}
1194
1195static int do_head_ref(const char *submodule, each_ref_fn fn, void *cb_data)
1196{
1197        unsigned char sha1[20];
1198        int flag;
1199
1200        if (submodule) {
1201                if (resolve_gitlink_ref(submodule, "HEAD", sha1) == 0)
1202                        return fn("HEAD", sha1, 0, cb_data);
1203
1204                return 0;
1205        }
1206
1207        if (!read_ref_full("HEAD", sha1, 1, &flag))
1208                return fn("HEAD", sha1, flag, cb_data);
1209
1210        return 0;
1211}
1212
1213int head_ref(each_ref_fn fn, void *cb_data)
1214{
1215        return do_head_ref(NULL, fn, cb_data);
1216}
1217
1218int head_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
1219{
1220        return do_head_ref(submodule, fn, cb_data);
1221}
1222
1223int for_each_ref(each_ref_fn fn, void *cb_data)
1224{
1225        return do_for_each_ref(NULL, "", fn, 0, 0, cb_data);
1226}
1227
1228int for_each_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
1229{
1230        return do_for_each_ref(submodule, "", fn, 0, 0, cb_data);
1231}
1232
1233int for_each_ref_in(const char *prefix, each_ref_fn fn, void *cb_data)
1234{
1235        return do_for_each_ref(NULL, prefix, fn, strlen(prefix), 0, cb_data);
1236}
1237
1238int for_each_ref_in_submodule(const char *submodule, const char *prefix,
1239                each_ref_fn fn, void *cb_data)
1240{
1241        return do_for_each_ref(submodule, prefix, fn, strlen(prefix), 0, cb_data);
1242}
1243
1244int for_each_tag_ref(each_ref_fn fn, void *cb_data)
1245{
1246        return for_each_ref_in("refs/tags/", fn, cb_data);
1247}
1248
1249int for_each_tag_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
1250{
1251        return for_each_ref_in_submodule(submodule, "refs/tags/", fn, cb_data);
1252}
1253
1254int for_each_branch_ref(each_ref_fn fn, void *cb_data)
1255{
1256        return for_each_ref_in("refs/heads/", fn, cb_data);
1257}
1258
1259int for_each_branch_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
1260{
1261        return for_each_ref_in_submodule(submodule, "refs/heads/", fn, cb_data);
1262}
1263
1264int for_each_remote_ref(each_ref_fn fn, void *cb_data)
1265{
1266        return for_each_ref_in("refs/remotes/", fn, cb_data);
1267}
1268
1269int for_each_remote_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
1270{
1271        return for_each_ref_in_submodule(submodule, "refs/remotes/", fn, cb_data);
1272}
1273
1274int for_each_replace_ref(each_ref_fn fn, void *cb_data)
1275{
1276        return do_for_each_ref(NULL, "refs/replace/", fn, 13, 0, cb_data);
1277}
1278
1279int head_ref_namespaced(each_ref_fn fn, void *cb_data)
1280{
1281        struct strbuf buf = STRBUF_INIT;
1282        int ret = 0;
1283        unsigned char sha1[20];
1284        int flag;
1285
1286        strbuf_addf(&buf, "%sHEAD", get_git_namespace());
1287        if (!read_ref_full(buf.buf, sha1, 1, &flag))
1288                ret = fn(buf.buf, sha1, flag, cb_data);
1289        strbuf_release(&buf);
1290
1291        return ret;
1292}
1293
1294int for_each_namespaced_ref(each_ref_fn fn, void *cb_data)
1295{
1296        struct strbuf buf = STRBUF_INIT;
1297        int ret;
1298        strbuf_addf(&buf, "%srefs/", get_git_namespace());
1299        ret = do_for_each_ref(NULL, buf.buf, fn, 0, 0, cb_data);
1300        strbuf_release(&buf);
1301        return ret;
1302}
1303
1304int for_each_glob_ref_in(each_ref_fn fn, const char *pattern,
1305        const char *prefix, void *cb_data)
1306{
1307        struct strbuf real_pattern = STRBUF_INIT;
1308        struct ref_filter filter;
1309        int ret;
1310
1311        if (!prefix && prefixcmp(pattern, "refs/"))
1312                strbuf_addstr(&real_pattern, "refs/");
1313        else if (prefix)
1314                strbuf_addstr(&real_pattern, prefix);
1315        strbuf_addstr(&real_pattern, pattern);
1316
1317        if (!has_glob_specials(pattern)) {
1318                /* Append implied '/' '*' if not present. */
1319                if (real_pattern.buf[real_pattern.len - 1] != '/')
1320                        strbuf_addch(&real_pattern, '/');
1321                /* No need to check for '*', there is none. */
1322                strbuf_addch(&real_pattern, '*');
1323        }
1324
1325        filter.pattern = real_pattern.buf;
1326        filter.fn = fn;
1327        filter.cb_data = cb_data;
1328        ret = for_each_ref(filter_refs, &filter);
1329
1330        strbuf_release(&real_pattern);
1331        return ret;
1332}
1333
1334int for_each_glob_ref(each_ref_fn fn, const char *pattern, void *cb_data)
1335{
1336        return for_each_glob_ref_in(fn, pattern, NULL, cb_data);
1337}
1338
1339int for_each_rawref(each_ref_fn fn, void *cb_data)
1340{
1341        return do_for_each_ref(NULL, "", fn, 0,
1342                               DO_FOR_EACH_INCLUDE_BROKEN, cb_data);
1343}
1344
1345const char *prettify_refname(const char *name)
1346{
1347        return name + (
1348                !prefixcmp(name, "refs/heads/") ? 11 :
1349                !prefixcmp(name, "refs/tags/") ? 10 :
1350                !prefixcmp(name, "refs/remotes/") ? 13 :
1351                0);
1352}
1353
1354const char *ref_rev_parse_rules[] = {
1355        "%.*s",
1356        "refs/%.*s",
1357        "refs/tags/%.*s",
1358        "refs/heads/%.*s",
1359        "refs/remotes/%.*s",
1360        "refs/remotes/%.*s/HEAD",
1361        NULL
1362};
1363
1364int refname_match(const char *abbrev_name, const char *full_name, const char **rules)
1365{
1366        const char **p;
1367        const int abbrev_name_len = strlen(abbrev_name);
1368
1369        for (p = rules; *p; p++) {
1370                if (!strcmp(full_name, mkpath(*p, abbrev_name_len, abbrev_name))) {
1371                        return 1;
1372                }
1373        }
1374
1375        return 0;
1376}
1377
1378static struct ref_lock *verify_lock(struct ref_lock *lock,
1379        const unsigned char *old_sha1, int mustexist)
1380{
1381        if (read_ref_full(lock->ref_name, lock->old_sha1, mustexist, NULL)) {
1382                error("Can't verify ref %s", lock->ref_name);
1383                unlock_ref(lock);
1384                return NULL;
1385        }
1386        if (hashcmp(lock->old_sha1, old_sha1)) {
1387                error("Ref %s is at %s but expected %s", lock->ref_name,
1388                        sha1_to_hex(lock->old_sha1), sha1_to_hex(old_sha1));
1389                unlock_ref(lock);
1390                return NULL;
1391        }
1392        return lock;
1393}
1394
1395static int remove_empty_directories(const char *file)
1396{
1397        /* we want to create a file but there is a directory there;
1398         * if that is an empty directory (or a directory that contains
1399         * only empty directories), remove them.
1400         */
1401        struct strbuf path;
1402        int result;
1403
1404        strbuf_init(&path, 20);
1405        strbuf_addstr(&path, file);
1406
1407        result = remove_dir_recursively(&path, REMOVE_DIR_EMPTY_ONLY);
1408
1409        strbuf_release(&path);
1410
1411        return result;
1412}
1413
1414/*
1415 * *string and *len will only be substituted, and *string returned (for
1416 * later free()ing) if the string passed in is a magic short-hand form
1417 * to name a branch.
1418 */
1419static char *substitute_branch_name(const char **string, int *len)
1420{
1421        struct strbuf buf = STRBUF_INIT;
1422        int ret = interpret_branch_name(*string, &buf);
1423
1424        if (ret == *len) {
1425                size_t size;
1426                *string = strbuf_detach(&buf, &size);
1427                *len = size;
1428                return (char *)*string;
1429        }
1430
1431        return NULL;
1432}
1433
1434int dwim_ref(const char *str, int len, unsigned char *sha1, char **ref)
1435{
1436        char *last_branch = substitute_branch_name(&str, &len);
1437        const char **p, *r;
1438        int refs_found = 0;
1439
1440        *ref = NULL;
1441        for (p = ref_rev_parse_rules; *p; p++) {
1442                char fullref[PATH_MAX];
1443                unsigned char sha1_from_ref[20];
1444                unsigned char *this_result;
1445                int flag;
1446
1447                this_result = refs_found ? sha1_from_ref : sha1;
1448                mksnpath(fullref, sizeof(fullref), *p, len, str);
1449                r = resolve_ref_unsafe(fullref, this_result, 1, &flag);
1450                if (r) {
1451                        if (!refs_found++)
1452                                *ref = xstrdup(r);
1453                        if (!warn_ambiguous_refs)
1454                                break;
1455                } else if ((flag & REF_ISSYMREF) && strcmp(fullref, "HEAD")) {
1456                        warning("ignoring dangling symref %s.", fullref);
1457                } else if ((flag & REF_ISBROKEN) && strchr(fullref, '/')) {
1458                        warning("ignoring broken ref %s.", fullref);
1459                }
1460        }
1461        free(last_branch);
1462        return refs_found;
1463}
1464
1465int dwim_log(const char *str, int len, unsigned char *sha1, char **log)
1466{
1467        char *last_branch = substitute_branch_name(&str, &len);
1468        const char **p;
1469        int logs_found = 0;
1470
1471        *log = NULL;
1472        for (p = ref_rev_parse_rules; *p; p++) {
1473                struct stat st;
1474                unsigned char hash[20];
1475                char path[PATH_MAX];
1476                const char *ref, *it;
1477
1478                mksnpath(path, sizeof(path), *p, len, str);
1479                ref = resolve_ref_unsafe(path, hash, 1, NULL);
1480                if (!ref)
1481                        continue;
1482                if (!stat(git_path("logs/%s", path), &st) &&
1483                    S_ISREG(st.st_mode))
1484                        it = path;
1485                else if (strcmp(ref, path) &&
1486                         !stat(git_path("logs/%s", ref), &st) &&
1487                         S_ISREG(st.st_mode))
1488                        it = ref;
1489                else
1490                        continue;
1491                if (!logs_found++) {
1492                        *log = xstrdup(it);
1493                        hashcpy(sha1, hash);
1494                }
1495                if (!warn_ambiguous_refs)
1496                        break;
1497        }
1498        free(last_branch);
1499        return logs_found;
1500}
1501
1502static struct ref_lock *lock_ref_sha1_basic(const char *refname,
1503                                            const unsigned char *old_sha1,
1504                                            int flags, int *type_p)
1505{
1506        char *ref_file;
1507        const char *orig_refname = refname;
1508        struct ref_lock *lock;
1509        int last_errno = 0;
1510        int type, lflags;
1511        int mustexist = (old_sha1 && !is_null_sha1(old_sha1));
1512        int missing = 0;
1513
1514        lock = xcalloc(1, sizeof(struct ref_lock));
1515        lock->lock_fd = -1;
1516
1517        refname = resolve_ref_unsafe(refname, lock->old_sha1, mustexist, &type);
1518        if (!refname && errno == EISDIR) {
1519                /* we are trying to lock foo but we used to
1520                 * have foo/bar which now does not exist;
1521                 * it is normal for the empty directory 'foo'
1522                 * to remain.
1523                 */
1524                ref_file = git_path("%s", orig_refname);
1525                if (remove_empty_directories(ref_file)) {
1526                        last_errno = errno;
1527                        error("there are still refs under '%s'", orig_refname);
1528                        goto error_return;
1529                }
1530                refname = resolve_ref_unsafe(orig_refname, lock->old_sha1, mustexist, &type);
1531        }
1532        if (type_p)
1533            *type_p = type;
1534        if (!refname) {
1535                last_errno = errno;
1536                error("unable to resolve reference %s: %s",
1537                        orig_refname, strerror(errno));
1538                goto error_return;
1539        }
1540        missing = is_null_sha1(lock->old_sha1);
1541        /* When the ref did not exist and we are creating it,
1542         * make sure there is no existing ref that is packed
1543         * whose name begins with our refname, nor a ref whose
1544         * name is a proper prefix of our refname.
1545         */
1546        if (missing &&
1547             !is_refname_available(refname, NULL, get_packed_refs(get_ref_cache(NULL)))) {
1548                last_errno = ENOTDIR;
1549                goto error_return;
1550        }
1551
1552        lock->lk = xcalloc(1, sizeof(struct lock_file));
1553
1554        lflags = LOCK_DIE_ON_ERROR;
1555        if (flags & REF_NODEREF) {
1556                refname = orig_refname;
1557                lflags |= LOCK_NODEREF;
1558        }
1559        lock->ref_name = xstrdup(refname);
1560        lock->orig_ref_name = xstrdup(orig_refname);
1561        ref_file = git_path("%s", refname);
1562        if (missing)
1563                lock->force_write = 1;
1564        if ((flags & REF_NODEREF) && (type & REF_ISSYMREF))
1565                lock->force_write = 1;
1566
1567        if (safe_create_leading_directories(ref_file)) {
1568                last_errno = errno;
1569                error("unable to create directory for %s", ref_file);
1570                goto error_return;
1571        }
1572
1573        lock->lock_fd = hold_lock_file_for_update(lock->lk, ref_file, lflags);
1574        return old_sha1 ? verify_lock(lock, old_sha1, mustexist) : lock;
1575
1576 error_return:
1577        unlock_ref(lock);
1578        errno = last_errno;
1579        return NULL;
1580}
1581
1582struct ref_lock *lock_ref_sha1(const char *refname, const unsigned char *old_sha1)
1583{
1584        char refpath[PATH_MAX];
1585        if (check_refname_format(refname, 0))
1586                return NULL;
1587        strcpy(refpath, mkpath("refs/%s", refname));
1588        return lock_ref_sha1_basic(refpath, old_sha1, 0, NULL);
1589}
1590
1591struct ref_lock *lock_any_ref_for_update(const char *refname,
1592                                         const unsigned char *old_sha1, int flags)
1593{
1594        if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL))
1595                return NULL;
1596        return lock_ref_sha1_basic(refname, old_sha1, flags, NULL);
1597}
1598
1599struct repack_without_ref_sb {
1600        const char *refname;
1601        int fd;
1602};
1603
1604static int repack_without_ref_fn(const char *refname, const unsigned char *sha1,
1605                                 int flags, void *cb_data)
1606{
1607        struct repack_without_ref_sb *data = cb_data;
1608        char line[PATH_MAX + 100];
1609        int len;
1610
1611        if (!strcmp(data->refname, refname))
1612                return 0;
1613        len = snprintf(line, sizeof(line), "%s %s\n",
1614                       sha1_to_hex(sha1), refname);
1615        /* this should not happen but just being defensive */
1616        if (len > sizeof(line))
1617                die("too long a refname '%s'", refname);
1618        write_or_die(data->fd, line, len);
1619        return 0;
1620}
1621
1622static struct lock_file packlock;
1623
1624static int repack_without_ref(const char *refname)
1625{
1626        struct repack_without_ref_sb data;
1627        struct ref_dir *packed = get_packed_refs(get_ref_cache(NULL));
1628        if (find_ref(packed, refname) == NULL)
1629                return 0;
1630        data.refname = refname;
1631        data.fd = hold_lock_file_for_update(&packlock, git_path("packed-refs"), 0);
1632        if (data.fd < 0) {
1633                unable_to_lock_error(git_path("packed-refs"), errno);
1634                return error("cannot delete '%s' from packed refs", refname);
1635        }
1636        do_for_each_ref_in_dir(packed, 0, "", repack_without_ref_fn, 0, 0, &data);
1637        return commit_lock_file(&packlock);
1638}
1639
1640int delete_ref(const char *refname, const unsigned char *sha1, int delopt)
1641{
1642        struct ref_lock *lock;
1643        int err, i = 0, ret = 0, flag = 0;
1644
1645        lock = lock_ref_sha1_basic(refname, sha1, 0, &flag);
1646        if (!lock)
1647                return 1;
1648        if (!(flag & REF_ISPACKED) || flag & REF_ISSYMREF) {
1649                /* loose */
1650                const char *path;
1651
1652                if (!(delopt & REF_NODEREF)) {
1653                        i = strlen(lock->lk->filename) - 5; /* .lock */
1654                        lock->lk->filename[i] = 0;
1655                        path = lock->lk->filename;
1656                } else {
1657                        path = git_path("%s", refname);
1658                }
1659                err = unlink_or_warn(path);
1660                if (err && errno != ENOENT)
1661                        ret = 1;
1662
1663                if (!(delopt & REF_NODEREF))
1664                        lock->lk->filename[i] = '.';
1665        }
1666        /* removing the loose one could have resurrected an earlier
1667         * packed one.  Also, if it was not loose we need to repack
1668         * without it.
1669         */
1670        ret |= repack_without_ref(refname);
1671
1672        unlink_or_warn(git_path("logs/%s", lock->ref_name));
1673        invalidate_ref_cache(NULL);
1674        unlock_ref(lock);
1675        return ret;
1676}
1677
1678/*
1679 * People using contrib's git-new-workdir have .git/logs/refs ->
1680 * /some/other/path/.git/logs/refs, and that may live on another device.
1681 *
1682 * IOW, to avoid cross device rename errors, the temporary renamed log must
1683 * live into logs/refs.
1684 */
1685#define TMP_RENAMED_LOG  "logs/refs/.tmp-renamed-log"
1686
1687int rename_ref(const char *oldrefname, const char *newrefname, const char *logmsg)
1688{
1689        unsigned char sha1[20], orig_sha1[20];
1690        int flag = 0, logmoved = 0;
1691        struct ref_lock *lock;
1692        struct stat loginfo;
1693        int log = !lstat(git_path("logs/%s", oldrefname), &loginfo);
1694        const char *symref = NULL;
1695        struct ref_cache *refs = get_ref_cache(NULL);
1696
1697        if (log && S_ISLNK(loginfo.st_mode))
1698                return error("reflog for %s is a symlink", oldrefname);
1699
1700        symref = resolve_ref_unsafe(oldrefname, orig_sha1, 1, &flag);
1701        if (flag & REF_ISSYMREF)
1702                return error("refname %s is a symbolic ref, renaming it is not supported",
1703                        oldrefname);
1704        if (!symref)
1705                return error("refname %s not found", oldrefname);
1706
1707        if (!is_refname_available(newrefname, oldrefname, get_packed_refs(refs)))
1708                return 1;
1709
1710        if (!is_refname_available(newrefname, oldrefname, get_loose_refs(refs)))
1711                return 1;
1712
1713        if (log && rename(git_path("logs/%s", oldrefname), git_path(TMP_RENAMED_LOG)))
1714                return error("unable to move logfile logs/%s to "TMP_RENAMED_LOG": %s",
1715                        oldrefname, strerror(errno));
1716
1717        if (delete_ref(oldrefname, orig_sha1, REF_NODEREF)) {
1718                error("unable to delete old %s", oldrefname);
1719                goto rollback;
1720        }
1721
1722        if (!read_ref_full(newrefname, sha1, 1, &flag) &&
1723            delete_ref(newrefname, sha1, REF_NODEREF)) {
1724                if (errno==EISDIR) {
1725                        if (remove_empty_directories(git_path("%s", newrefname))) {
1726                                error("Directory not empty: %s", newrefname);
1727                                goto rollback;
1728                        }
1729                } else {
1730                        error("unable to delete existing %s", newrefname);
1731                        goto rollback;
1732                }
1733        }
1734
1735        if (log && safe_create_leading_directories(git_path("logs/%s", newrefname))) {
1736                error("unable to create directory for %s", newrefname);
1737                goto rollback;
1738        }
1739
1740 retry:
1741        if (log && rename(git_path(TMP_RENAMED_LOG), git_path("logs/%s", newrefname))) {
1742                if (errno==EISDIR || errno==ENOTDIR) {
1743                        /*
1744                         * rename(a, b) when b is an existing
1745                         * directory ought to result in ISDIR, but
1746                         * Solaris 5.8 gives ENOTDIR.  Sheesh.
1747                         */
1748                        if (remove_empty_directories(git_path("logs/%s", newrefname))) {
1749                                error("Directory not empty: logs/%s", newrefname);
1750                                goto rollback;
1751                        }
1752                        goto retry;
1753                } else {
1754                        error("unable to move logfile "TMP_RENAMED_LOG" to logs/%s: %s",
1755                                newrefname, strerror(errno));
1756                        goto rollback;
1757                }
1758        }
1759        logmoved = log;
1760
1761        lock = lock_ref_sha1_basic(newrefname, NULL, 0, NULL);
1762        if (!lock) {
1763                error("unable to lock %s for update", newrefname);
1764                goto rollback;
1765        }
1766        lock->force_write = 1;
1767        hashcpy(lock->old_sha1, orig_sha1);
1768        if (write_ref_sha1(lock, orig_sha1, logmsg)) {
1769                error("unable to write current sha1 into %s", newrefname);
1770                goto rollback;
1771        }
1772
1773        return 0;
1774
1775 rollback:
1776        lock = lock_ref_sha1_basic(oldrefname, NULL, 0, NULL);
1777        if (!lock) {
1778                error("unable to lock %s for rollback", oldrefname);
1779                goto rollbacklog;
1780        }
1781
1782        lock->force_write = 1;
1783        flag = log_all_ref_updates;
1784        log_all_ref_updates = 0;
1785        if (write_ref_sha1(lock, orig_sha1, NULL))
1786                error("unable to write current sha1 into %s", oldrefname);
1787        log_all_ref_updates = flag;
1788
1789 rollbacklog:
1790        if (logmoved && rename(git_path("logs/%s", newrefname), git_path("logs/%s", oldrefname)))
1791                error("unable to restore logfile %s from %s: %s",
1792                        oldrefname, newrefname, strerror(errno));
1793        if (!logmoved && log &&
1794            rename(git_path(TMP_RENAMED_LOG), git_path("logs/%s", oldrefname)))
1795                error("unable to restore logfile %s from "TMP_RENAMED_LOG": %s",
1796                        oldrefname, strerror(errno));
1797
1798        return 1;
1799}
1800
1801int close_ref(struct ref_lock *lock)
1802{
1803        if (close_lock_file(lock->lk))
1804                return -1;
1805        lock->lock_fd = -1;
1806        return 0;
1807}
1808
1809int commit_ref(struct ref_lock *lock)
1810{
1811        if (commit_lock_file(lock->lk))
1812                return -1;
1813        lock->lock_fd = -1;
1814        return 0;
1815}
1816
1817void unlock_ref(struct ref_lock *lock)
1818{
1819        /* Do not free lock->lk -- atexit() still looks at them */
1820        if (lock->lk)
1821                rollback_lock_file(lock->lk);
1822        free(lock->ref_name);
1823        free(lock->orig_ref_name);
1824        free(lock);
1825}
1826
1827/*
1828 * copy the reflog message msg to buf, which has been allocated sufficiently
1829 * large, while cleaning up the whitespaces.  Especially, convert LF to space,
1830 * because reflog file is one line per entry.
1831 */
1832static int copy_msg(char *buf, const char *msg)
1833{
1834        char *cp = buf;
1835        char c;
1836        int wasspace = 1;
1837
1838        *cp++ = '\t';
1839        while ((c = *msg++)) {
1840                if (wasspace && isspace(c))
1841                        continue;
1842                wasspace = isspace(c);
1843                if (wasspace)
1844                        c = ' ';
1845                *cp++ = c;
1846        }
1847        while (buf < cp && isspace(cp[-1]))
1848                cp--;
1849        *cp++ = '\n';
1850        return cp - buf;
1851}
1852
1853int log_ref_setup(const char *refname, char *logfile, int bufsize)
1854{
1855        int logfd, oflags = O_APPEND | O_WRONLY;
1856
1857        git_snpath(logfile, bufsize, "logs/%s", refname);
1858        if (log_all_ref_updates &&
1859            (!prefixcmp(refname, "refs/heads/") ||
1860             !prefixcmp(refname, "refs/remotes/") ||
1861             !prefixcmp(refname, "refs/notes/") ||
1862             !strcmp(refname, "HEAD"))) {
1863                if (safe_create_leading_directories(logfile) < 0)
1864                        return error("unable to create directory for %s",
1865                                     logfile);
1866                oflags |= O_CREAT;
1867        }
1868
1869        logfd = open(logfile, oflags, 0666);
1870        if (logfd < 0) {
1871                if (!(oflags & O_CREAT) && errno == ENOENT)
1872                        return 0;
1873
1874                if ((oflags & O_CREAT) && errno == EISDIR) {
1875                        if (remove_empty_directories(logfile)) {
1876                                return error("There are still logs under '%s'",
1877                                             logfile);
1878                        }
1879                        logfd = open(logfile, oflags, 0666);
1880                }
1881
1882                if (logfd < 0)
1883                        return error("Unable to append to %s: %s",
1884                                     logfile, strerror(errno));
1885        }
1886
1887        adjust_shared_perm(logfile);
1888        close(logfd);
1889        return 0;
1890}
1891
1892static int log_ref_write(const char *refname, const unsigned char *old_sha1,
1893                         const unsigned char *new_sha1, const char *msg)
1894{
1895        int logfd, result, written, oflags = O_APPEND | O_WRONLY;
1896        unsigned maxlen, len;
1897        int msglen;
1898        char log_file[PATH_MAX];
1899        char *logrec;
1900        const char *committer;
1901
1902        if (log_all_ref_updates < 0)
1903                log_all_ref_updates = !is_bare_repository();
1904
1905        result = log_ref_setup(refname, log_file, sizeof(log_file));
1906        if (result)
1907                return result;
1908
1909        logfd = open(log_file, oflags);
1910        if (logfd < 0)
1911                return 0;
1912        msglen = msg ? strlen(msg) : 0;
1913        committer = git_committer_info(0);
1914        maxlen = strlen(committer) + msglen + 100;
1915        logrec = xmalloc(maxlen);
1916        len = sprintf(logrec, "%s %s %s\n",
1917                      sha1_to_hex(old_sha1),
1918                      sha1_to_hex(new_sha1),
1919                      committer);
1920        if (msglen)
1921                len += copy_msg(logrec + len - 1, msg) - 1;
1922        written = len <= maxlen ? write_in_full(logfd, logrec, len) : -1;
1923        free(logrec);
1924        if (close(logfd) != 0 || written != len)
1925                return error("Unable to append to %s", log_file);
1926        return 0;
1927}
1928
1929static int is_branch(const char *refname)
1930{
1931        return !strcmp(refname, "HEAD") || !prefixcmp(refname, "refs/heads/");
1932}
1933
1934int write_ref_sha1(struct ref_lock *lock,
1935        const unsigned char *sha1, const char *logmsg)
1936{
1937        static char term = '\n';
1938        struct object *o;
1939
1940        if (!lock)
1941                return -1;
1942        if (!lock->force_write && !hashcmp(lock->old_sha1, sha1)) {
1943                unlock_ref(lock);
1944                return 0;
1945        }
1946        o = parse_object(sha1);
1947        if (!o) {
1948                error("Trying to write ref %s with nonexistent object %s",
1949                        lock->ref_name, sha1_to_hex(sha1));
1950                unlock_ref(lock);
1951                return -1;
1952        }
1953        if (o->type != OBJ_COMMIT && is_branch(lock->ref_name)) {
1954                error("Trying to write non-commit object %s to branch %s",
1955                        sha1_to_hex(sha1), lock->ref_name);
1956                unlock_ref(lock);
1957                return -1;
1958        }
1959        if (write_in_full(lock->lock_fd, sha1_to_hex(sha1), 40) != 40 ||
1960            write_in_full(lock->lock_fd, &term, 1) != 1
1961                || close_ref(lock) < 0) {
1962                error("Couldn't write %s", lock->lk->filename);
1963                unlock_ref(lock);
1964                return -1;
1965        }
1966        clear_loose_ref_cache(get_ref_cache(NULL));
1967        if (log_ref_write(lock->ref_name, lock->old_sha1, sha1, logmsg) < 0 ||
1968            (strcmp(lock->ref_name, lock->orig_ref_name) &&
1969             log_ref_write(lock->orig_ref_name, lock->old_sha1, sha1, logmsg) < 0)) {
1970                unlock_ref(lock);
1971                return -1;
1972        }
1973        if (strcmp(lock->orig_ref_name, "HEAD") != 0) {
1974                /*
1975                 * Special hack: If a branch is updated directly and HEAD
1976                 * points to it (may happen on the remote side of a push
1977                 * for example) then logically the HEAD reflog should be
1978                 * updated too.
1979                 * A generic solution implies reverse symref information,
1980                 * but finding all symrefs pointing to the given branch
1981                 * would be rather costly for this rare event (the direct
1982                 * update of a branch) to be worth it.  So let's cheat and
1983                 * check with HEAD only which should cover 99% of all usage
1984                 * scenarios (even 100% of the default ones).
1985                 */
1986                unsigned char head_sha1[20];
1987                int head_flag;
1988                const char *head_ref;
1989                head_ref = resolve_ref_unsafe("HEAD", head_sha1, 1, &head_flag);
1990                if (head_ref && (head_flag & REF_ISSYMREF) &&
1991                    !strcmp(head_ref, lock->ref_name))
1992                        log_ref_write("HEAD", lock->old_sha1, sha1, logmsg);
1993        }
1994        if (commit_ref(lock)) {
1995                error("Couldn't set %s", lock->ref_name);
1996                unlock_ref(lock);
1997                return -1;
1998        }
1999        unlock_ref(lock);
2000        return 0;
2001}
2002
2003int create_symref(const char *ref_target, const char *refs_heads_master,
2004                  const char *logmsg)
2005{
2006        const char *lockpath;
2007        char ref[1000];
2008        int fd, len, written;
2009        char *git_HEAD = git_pathdup("%s", ref_target);
2010        unsigned char old_sha1[20], new_sha1[20];
2011
2012        if (logmsg && read_ref(ref_target, old_sha1))
2013                hashclr(old_sha1);
2014
2015        if (safe_create_leading_directories(git_HEAD) < 0)
2016                return error("unable to create directory for %s", git_HEAD);
2017
2018#ifndef NO_SYMLINK_HEAD
2019        if (prefer_symlink_refs) {
2020                unlink(git_HEAD);
2021                if (!symlink(refs_heads_master, git_HEAD))
2022                        goto done;
2023                fprintf(stderr, "no symlink - falling back to symbolic ref\n");
2024        }
2025#endif
2026
2027        len = snprintf(ref, sizeof(ref), "ref: %s\n", refs_heads_master);
2028        if (sizeof(ref) <= len) {
2029                error("refname too long: %s", refs_heads_master);
2030                goto error_free_return;
2031        }
2032        lockpath = mkpath("%s.lock", git_HEAD);
2033        fd = open(lockpath, O_CREAT | O_EXCL | O_WRONLY, 0666);
2034        if (fd < 0) {
2035                error("Unable to open %s for writing", lockpath);
2036                goto error_free_return;
2037        }
2038        written = write_in_full(fd, ref, len);
2039        if (close(fd) != 0 || written != len) {
2040                error("Unable to write to %s", lockpath);
2041                goto error_unlink_return;
2042        }
2043        if (rename(lockpath, git_HEAD) < 0) {
2044                error("Unable to create %s", git_HEAD);
2045                goto error_unlink_return;
2046        }
2047        if (adjust_shared_perm(git_HEAD)) {
2048                error("Unable to fix permissions on %s", lockpath);
2049        error_unlink_return:
2050                unlink_or_warn(lockpath);
2051        error_free_return:
2052                free(git_HEAD);
2053                return -1;
2054        }
2055
2056#ifndef NO_SYMLINK_HEAD
2057        done:
2058#endif
2059        if (logmsg && !read_ref(refs_heads_master, new_sha1))
2060                log_ref_write(ref_target, old_sha1, new_sha1, logmsg);
2061
2062        free(git_HEAD);
2063        return 0;
2064}
2065
2066static char *ref_msg(const char *line, const char *endp)
2067{
2068        const char *ep;
2069        line += 82;
2070        ep = memchr(line, '\n', endp - line);
2071        if (!ep)
2072                ep = endp;
2073        return xmemdupz(line, ep - line);
2074}
2075
2076int read_ref_at(const char *refname, unsigned long at_time, int cnt,
2077                unsigned char *sha1, char **msg,
2078                unsigned long *cutoff_time, int *cutoff_tz, int *cutoff_cnt)
2079{
2080        const char *logfile, *logdata, *logend, *rec, *lastgt, *lastrec;
2081        char *tz_c;
2082        int logfd, tz, reccnt = 0;
2083        struct stat st;
2084        unsigned long date;
2085        unsigned char logged_sha1[20];
2086        void *log_mapped;
2087        size_t mapsz;
2088
2089        logfile = git_path("logs/%s", refname);
2090        logfd = open(logfile, O_RDONLY, 0);
2091        if (logfd < 0)
2092                die_errno("Unable to read log '%s'", logfile);
2093        fstat(logfd, &st);
2094        if (!st.st_size)
2095                die("Log %s is empty.", logfile);
2096        mapsz = xsize_t(st.st_size);
2097        log_mapped = xmmap(NULL, mapsz, PROT_READ, MAP_PRIVATE, logfd, 0);
2098        logdata = log_mapped;
2099        close(logfd);
2100
2101        lastrec = NULL;
2102        rec = logend = logdata + st.st_size;
2103        while (logdata < rec) {
2104                reccnt++;
2105                if (logdata < rec && *(rec-1) == '\n')
2106                        rec--;
2107                lastgt = NULL;
2108                while (logdata < rec && *(rec-1) != '\n') {
2109                        rec--;
2110                        if (*rec == '>')
2111                                lastgt = rec;
2112                }
2113                if (!lastgt)
2114                        die("Log %s is corrupt.", logfile);
2115                date = strtoul(lastgt + 1, &tz_c, 10);
2116                if (date <= at_time || cnt == 0) {
2117                        tz = strtoul(tz_c, NULL, 10);
2118                        if (msg)
2119                                *msg = ref_msg(rec, logend);
2120                        if (cutoff_time)
2121                                *cutoff_time = date;
2122                        if (cutoff_tz)
2123                                *cutoff_tz = tz;
2124                        if (cutoff_cnt)
2125                                *cutoff_cnt = reccnt - 1;
2126                        if (lastrec) {
2127                                if (get_sha1_hex(lastrec, logged_sha1))
2128                                        die("Log %s is corrupt.", logfile);
2129                                if (get_sha1_hex(rec + 41, sha1))
2130                                        die("Log %s is corrupt.", logfile);
2131                                if (hashcmp(logged_sha1, sha1)) {
2132                                        warning("Log %s has gap after %s.",
2133                                                logfile, show_date(date, tz, DATE_RFC2822));
2134                                }
2135                        }
2136                        else if (date == at_time) {
2137                                if (get_sha1_hex(rec + 41, sha1))
2138                                        die("Log %s is corrupt.", logfile);
2139                        }
2140                        else {
2141                                if (get_sha1_hex(rec + 41, logged_sha1))
2142                                        die("Log %s is corrupt.", logfile);
2143                                if (hashcmp(logged_sha1, sha1)) {
2144                                        warning("Log %s unexpectedly ended on %s.",
2145                                                logfile, show_date(date, tz, DATE_RFC2822));
2146                                }
2147                        }
2148                        munmap(log_mapped, mapsz);
2149                        return 0;
2150                }
2151                lastrec = rec;
2152                if (cnt > 0)
2153                        cnt--;
2154        }
2155
2156        rec = logdata;
2157        while (rec < logend && *rec != '>' && *rec != '\n')
2158                rec++;
2159        if (rec == logend || *rec == '\n')
2160                die("Log %s is corrupt.", logfile);
2161        date = strtoul(rec + 1, &tz_c, 10);
2162        tz = strtoul(tz_c, NULL, 10);
2163        if (get_sha1_hex(logdata, sha1))
2164                die("Log %s is corrupt.", logfile);
2165        if (is_null_sha1(sha1)) {
2166                if (get_sha1_hex(logdata + 41, sha1))
2167                        die("Log %s is corrupt.", logfile);
2168        }
2169        if (msg)
2170                *msg = ref_msg(logdata, logend);
2171        munmap(log_mapped, mapsz);
2172
2173        if (cutoff_time)
2174                *cutoff_time = date;
2175        if (cutoff_tz)
2176                *cutoff_tz = tz;
2177        if (cutoff_cnt)
2178                *cutoff_cnt = reccnt;
2179        return 1;
2180}
2181
2182int for_each_recent_reflog_ent(const char *refname, each_reflog_ent_fn fn, long ofs, void *cb_data)
2183{
2184        const char *logfile;
2185        FILE *logfp;
2186        struct strbuf sb = STRBUF_INIT;
2187        int ret = 0;
2188
2189        logfile = git_path("logs/%s", refname);
2190        logfp = fopen(logfile, "r");
2191        if (!logfp)
2192                return -1;
2193
2194        if (ofs) {
2195                struct stat statbuf;
2196                if (fstat(fileno(logfp), &statbuf) ||
2197                    statbuf.st_size < ofs ||
2198                    fseek(logfp, -ofs, SEEK_END) ||
2199                    strbuf_getwholeline(&sb, logfp, '\n')) {
2200                        fclose(logfp);
2201                        strbuf_release(&sb);
2202                        return -1;
2203                }
2204        }
2205
2206        while (!strbuf_getwholeline(&sb, logfp, '\n')) {
2207                unsigned char osha1[20], nsha1[20];
2208                char *email_end, *message;
2209                unsigned long timestamp;
2210                int tz;
2211
2212                /* old SP new SP name <email> SP time TAB msg LF */
2213                if (sb.len < 83 || sb.buf[sb.len - 1] != '\n' ||
2214                    get_sha1_hex(sb.buf, osha1) || sb.buf[40] != ' ' ||
2215                    get_sha1_hex(sb.buf + 41, nsha1) || sb.buf[81] != ' ' ||
2216                    !(email_end = strchr(sb.buf + 82, '>')) ||
2217                    email_end[1] != ' ' ||
2218                    !(timestamp = strtoul(email_end + 2, &message, 10)) ||
2219                    !message || message[0] != ' ' ||
2220                    (message[1] != '+' && message[1] != '-') ||
2221                    !isdigit(message[2]) || !isdigit(message[3]) ||
2222                    !isdigit(message[4]) || !isdigit(message[5]))
2223                        continue; /* corrupt? */
2224                email_end[1] = '\0';
2225                tz = strtol(message + 1, NULL, 10);
2226                if (message[6] != '\t')
2227                        message += 6;
2228                else
2229                        message += 7;
2230                ret = fn(osha1, nsha1, sb.buf + 82, timestamp, tz, message,
2231                         cb_data);
2232                if (ret)
2233                        break;
2234        }
2235        fclose(logfp);
2236        strbuf_release(&sb);
2237        return ret;
2238}
2239
2240int for_each_reflog_ent(const char *refname, each_reflog_ent_fn fn, void *cb_data)
2241{
2242        return for_each_recent_reflog_ent(refname, fn, 0, cb_data);
2243}
2244
2245static int do_for_each_reflog(const char *base, each_ref_fn fn, void *cb_data)
2246{
2247        DIR *d = opendir(git_path("logs/%s", base));
2248        int retval = 0;
2249        struct dirent *de;
2250        int baselen;
2251        char *log;
2252
2253        if (!d)
2254                return *base ? errno : 0;
2255
2256        baselen = strlen(base);
2257        log = xmalloc(baselen + 257);
2258        memcpy(log, base, baselen);
2259        if (baselen && base[baselen-1] != '/')
2260                log[baselen++] = '/';
2261
2262        while ((de = readdir(d)) != NULL) {
2263                struct stat st;
2264                int namelen;
2265
2266                if (de->d_name[0] == '.')
2267                        continue;
2268                namelen = strlen(de->d_name);
2269                if (namelen > 255)
2270                        continue;
2271                if (has_extension(de->d_name, ".lock"))
2272                        continue;
2273                memcpy(log + baselen, de->d_name, namelen+1);
2274                if (stat(git_path("logs/%s", log), &st) < 0)
2275                        continue;
2276                if (S_ISDIR(st.st_mode)) {
2277                        retval = do_for_each_reflog(log, fn, cb_data);
2278                } else {
2279                        unsigned char sha1[20];
2280                        if (read_ref_full(log, sha1, 0, NULL))
2281                                retval = error("bad ref for %s", log);
2282                        else
2283                                retval = fn(log, sha1, 0, cb_data);
2284                }
2285                if (retval)
2286                        break;
2287        }
2288        free(log);
2289        closedir(d);
2290        return retval;
2291}
2292
2293int for_each_reflog(each_ref_fn fn, void *cb_data)
2294{
2295        return do_for_each_reflog("", fn, cb_data);
2296}
2297
2298int update_ref(const char *action, const char *refname,
2299                const unsigned char *sha1, const unsigned char *oldval,
2300                int flags, enum action_on_err onerr)
2301{
2302        static struct ref_lock *lock;
2303        lock = lock_any_ref_for_update(refname, oldval, flags);
2304        if (!lock) {
2305                const char *str = "Cannot lock the ref '%s'.";
2306                switch (onerr) {
2307                case MSG_ON_ERR: error(str, refname); break;
2308                case DIE_ON_ERR: die(str, refname); break;
2309                case QUIET_ON_ERR: break;
2310                }
2311                return 1;
2312        }
2313        if (write_ref_sha1(lock, sha1, action) < 0) {
2314                const char *str = "Cannot update the ref '%s'.";
2315                switch (onerr) {
2316                case MSG_ON_ERR: error(str, refname); break;
2317                case DIE_ON_ERR: die(str, refname); break;
2318                case QUIET_ON_ERR: break;
2319                }
2320                return 1;
2321        }
2322        return 0;
2323}
2324
2325struct ref *find_ref_by_name(const struct ref *list, const char *name)
2326{
2327        for ( ; list; list = list->next)
2328                if (!strcmp(list->name, name))
2329                        return (struct ref *)list;
2330        return NULL;
2331}
2332
2333/*
2334 * generate a format suitable for scanf from a ref_rev_parse_rules
2335 * rule, that is replace the "%.*s" spec with a "%s" spec
2336 */
2337static void gen_scanf_fmt(char *scanf_fmt, const char *rule)
2338{
2339        char *spec;
2340
2341        spec = strstr(rule, "%.*s");
2342        if (!spec || strstr(spec + 4, "%.*s"))
2343                die("invalid rule in ref_rev_parse_rules: %s", rule);
2344
2345        /* copy all until spec */
2346        strncpy(scanf_fmt, rule, spec - rule);
2347        scanf_fmt[spec - rule] = '\0';
2348        /* copy new spec */
2349        strcat(scanf_fmt, "%s");
2350        /* copy remaining rule */
2351        strcat(scanf_fmt, spec + 4);
2352
2353        return;
2354}
2355
2356char *shorten_unambiguous_ref(const char *refname, int strict)
2357{
2358        int i;
2359        static char **scanf_fmts;
2360        static int nr_rules;
2361        char *short_name;
2362
2363        /* pre generate scanf formats from ref_rev_parse_rules[] */
2364        if (!nr_rules) {
2365                size_t total_len = 0;
2366
2367                /* the rule list is NULL terminated, count them first */
2368                for (; ref_rev_parse_rules[nr_rules]; nr_rules++)
2369                        /* no +1 because strlen("%s") < strlen("%.*s") */
2370                        total_len += strlen(ref_rev_parse_rules[nr_rules]);
2371
2372                scanf_fmts = xmalloc(nr_rules * sizeof(char *) + total_len);
2373
2374                total_len = 0;
2375                for (i = 0; i < nr_rules; i++) {
2376                        scanf_fmts[i] = (char *)&scanf_fmts[nr_rules]
2377                                        + total_len;
2378                        gen_scanf_fmt(scanf_fmts[i], ref_rev_parse_rules[i]);
2379                        total_len += strlen(ref_rev_parse_rules[i]);
2380                }
2381        }
2382
2383        /* bail out if there are no rules */
2384        if (!nr_rules)
2385                return xstrdup(refname);
2386
2387        /* buffer for scanf result, at most refname must fit */
2388        short_name = xstrdup(refname);
2389
2390        /* skip first rule, it will always match */
2391        for (i = nr_rules - 1; i > 0 ; --i) {
2392                int j;
2393                int rules_to_fail = i;
2394                int short_name_len;
2395
2396                if (1 != sscanf(refname, scanf_fmts[i], short_name))
2397                        continue;
2398
2399                short_name_len = strlen(short_name);
2400
2401                /*
2402                 * in strict mode, all (except the matched one) rules
2403                 * must fail to resolve to a valid non-ambiguous ref
2404                 */
2405                if (strict)
2406                        rules_to_fail = nr_rules;
2407
2408                /*
2409                 * check if the short name resolves to a valid ref,
2410                 * but use only rules prior to the matched one
2411                 */
2412                for (j = 0; j < rules_to_fail; j++) {
2413                        const char *rule = ref_rev_parse_rules[j];
2414                        char refname[PATH_MAX];
2415
2416                        /* skip matched rule */
2417                        if (i == j)
2418                                continue;
2419
2420                        /*
2421                         * the short name is ambiguous, if it resolves
2422                         * (with this previous rule) to a valid ref
2423                         * read_ref() returns 0 on success
2424                         */
2425                        mksnpath(refname, sizeof(refname),
2426                                 rule, short_name_len, short_name);
2427                        if (ref_exists(refname))
2428                                break;
2429                }
2430
2431                /*
2432                 * short name is non-ambiguous if all previous rules
2433                 * haven't resolved to a valid ref
2434                 */
2435                if (j == rules_to_fail)
2436                        return short_name;
2437        }
2438
2439        free(short_name);
2440        return xstrdup(refname);
2441}