read-cache.con commit Merge branch 'jk/stream-pack-non-delta-clarification' (c657aa0)
   1/*
   2 * GIT - The information manager from hell
   3 *
   4 * Copyright (C) Linus Torvalds, 2005
   5 */
   6#define NO_THE_INDEX_COMPATIBILITY_MACROS
   7#include "cache.h"
   8#include "config.h"
   9#include "diff.h"
  10#include "diffcore.h"
  11#include "tempfile.h"
  12#include "lockfile.h"
  13#include "cache-tree.h"
  14#include "refs.h"
  15#include "dir.h"
  16#include "object-store.h"
  17#include "tree.h"
  18#include "commit.h"
  19#include "blob.h"
  20#include "resolve-undo.h"
  21#include "strbuf.h"
  22#include "varint.h"
  23#include "split-index.h"
  24#include "utf8.h"
  25#include "fsmonitor.h"
  26#include "thread-utils.h"
  27#include "progress.h"
  28
  29/* Mask for the name length in ce_flags in the on-disk index */
  30
  31#define CE_NAMEMASK  (0x0fff)
  32
  33/* Index extensions.
  34 *
  35 * The first letter should be 'A'..'Z' for extensions that are not
  36 * necessary for a correct operation (i.e. optimization data).
  37 * When new extensions are added that _needs_ to be understood in
  38 * order to correctly interpret the index file, pick character that
  39 * is outside the range, to cause the reader to abort.
  40 */
  41
  42#define CACHE_EXT(s) ( (s[0]<<24)|(s[1]<<16)|(s[2]<<8)|(s[3]) )
  43#define CACHE_EXT_TREE 0x54524545       /* "TREE" */
  44#define CACHE_EXT_RESOLVE_UNDO 0x52455543 /* "REUC" */
  45#define CACHE_EXT_LINK 0x6c696e6b         /* "link" */
  46#define CACHE_EXT_UNTRACKED 0x554E5452    /* "UNTR" */
  47#define CACHE_EXT_FSMONITOR 0x46534D4E    /* "FSMN" */
  48#define CACHE_EXT_ENDOFINDEXENTRIES 0x454F4945  /* "EOIE" */
  49#define CACHE_EXT_INDEXENTRYOFFSETTABLE 0x49454F54 /* "IEOT" */
  50
  51/* changes that can be kept in $GIT_DIR/index (basically all extensions) */
  52#define EXTMASK (RESOLVE_UNDO_CHANGED | CACHE_TREE_CHANGED | \
  53                 CE_ENTRY_ADDED | CE_ENTRY_REMOVED | CE_ENTRY_CHANGED | \
  54                 SPLIT_INDEX_ORDERED | UNTRACKED_CHANGED | FSMONITOR_CHANGED)
  55
  56
  57/*
  58 * This is an estimate of the pathname length in the index.  We use
  59 * this for V4 index files to guess the un-deltafied size of the index
  60 * in memory because of pathname deltafication.  This is not required
  61 * for V2/V3 index formats because their pathnames are not compressed.
  62 * If the initial amount of memory set aside is not sufficient, the
  63 * mem pool will allocate extra memory.
  64 */
  65#define CACHE_ENTRY_PATH_LENGTH 80
  66
  67static inline struct cache_entry *mem_pool__ce_alloc(struct mem_pool *mem_pool, size_t len)
  68{
  69        struct cache_entry *ce;
  70        ce = mem_pool_alloc(mem_pool, cache_entry_size(len));
  71        ce->mem_pool_allocated = 1;
  72        return ce;
  73}
  74
  75static inline struct cache_entry *mem_pool__ce_calloc(struct mem_pool *mem_pool, size_t len)
  76{
  77        struct cache_entry * ce;
  78        ce = mem_pool_calloc(mem_pool, 1, cache_entry_size(len));
  79        ce->mem_pool_allocated = 1;
  80        return ce;
  81}
  82
  83static struct mem_pool *find_mem_pool(struct index_state *istate)
  84{
  85        struct mem_pool **pool_ptr;
  86
  87        if (istate->split_index && istate->split_index->base)
  88                pool_ptr = &istate->split_index->base->ce_mem_pool;
  89        else
  90                pool_ptr = &istate->ce_mem_pool;
  91
  92        if (!*pool_ptr)
  93                mem_pool_init(pool_ptr, 0);
  94
  95        return *pool_ptr;
  96}
  97
  98struct index_state the_index;
  99static const char *alternate_index_output;
 100
 101static void set_index_entry(struct index_state *istate, int nr, struct cache_entry *ce)
 102{
 103        istate->cache[nr] = ce;
 104        add_name_hash(istate, ce);
 105}
 106
 107static void replace_index_entry(struct index_state *istate, int nr, struct cache_entry *ce)
 108{
 109        struct cache_entry *old = istate->cache[nr];
 110
 111        replace_index_entry_in_base(istate, old, ce);
 112        remove_name_hash(istate, old);
 113        discard_cache_entry(old);
 114        ce->ce_flags &= ~CE_HASHED;
 115        set_index_entry(istate, nr, ce);
 116        ce->ce_flags |= CE_UPDATE_IN_BASE;
 117        mark_fsmonitor_invalid(istate, ce);
 118        istate->cache_changed |= CE_ENTRY_CHANGED;
 119}
 120
 121void rename_index_entry_at(struct index_state *istate, int nr, const char *new_name)
 122{
 123        struct cache_entry *old_entry = istate->cache[nr], *new_entry;
 124        int namelen = strlen(new_name);
 125
 126        new_entry = make_empty_cache_entry(istate, namelen);
 127        copy_cache_entry(new_entry, old_entry);
 128        new_entry->ce_flags &= ~CE_HASHED;
 129        new_entry->ce_namelen = namelen;
 130        new_entry->index = 0;
 131        memcpy(new_entry->name, new_name, namelen + 1);
 132
 133        cache_tree_invalidate_path(istate, old_entry->name);
 134        untracked_cache_remove_from_index(istate, old_entry->name);
 135        remove_index_entry_at(istate, nr);
 136        add_index_entry(istate, new_entry, ADD_CACHE_OK_TO_ADD|ADD_CACHE_OK_TO_REPLACE);
 137}
 138
 139void fill_stat_data(struct stat_data *sd, struct stat *st)
 140{
 141        sd->sd_ctime.sec = (unsigned int)st->st_ctime;
 142        sd->sd_mtime.sec = (unsigned int)st->st_mtime;
 143        sd->sd_ctime.nsec = ST_CTIME_NSEC(*st);
 144        sd->sd_mtime.nsec = ST_MTIME_NSEC(*st);
 145        sd->sd_dev = st->st_dev;
 146        sd->sd_ino = st->st_ino;
 147        sd->sd_uid = st->st_uid;
 148        sd->sd_gid = st->st_gid;
 149        sd->sd_size = st->st_size;
 150}
 151
 152int match_stat_data(const struct stat_data *sd, struct stat *st)
 153{
 154        int changed = 0;
 155
 156        if (sd->sd_mtime.sec != (unsigned int)st->st_mtime)
 157                changed |= MTIME_CHANGED;
 158        if (trust_ctime && check_stat &&
 159            sd->sd_ctime.sec != (unsigned int)st->st_ctime)
 160                changed |= CTIME_CHANGED;
 161
 162#ifdef USE_NSEC
 163        if (check_stat && sd->sd_mtime.nsec != ST_MTIME_NSEC(*st))
 164                changed |= MTIME_CHANGED;
 165        if (trust_ctime && check_stat &&
 166            sd->sd_ctime.nsec != ST_CTIME_NSEC(*st))
 167                changed |= CTIME_CHANGED;
 168#endif
 169
 170        if (check_stat) {
 171                if (sd->sd_uid != (unsigned int) st->st_uid ||
 172                        sd->sd_gid != (unsigned int) st->st_gid)
 173                        changed |= OWNER_CHANGED;
 174                if (sd->sd_ino != (unsigned int) st->st_ino)
 175                        changed |= INODE_CHANGED;
 176        }
 177
 178#ifdef USE_STDEV
 179        /*
 180         * st_dev breaks on network filesystems where different
 181         * clients will have different views of what "device"
 182         * the filesystem is on
 183         */
 184        if (check_stat && sd->sd_dev != (unsigned int) st->st_dev)
 185                        changed |= INODE_CHANGED;
 186#endif
 187
 188        if (sd->sd_size != (unsigned int) st->st_size)
 189                changed |= DATA_CHANGED;
 190
 191        return changed;
 192}
 193
 194/*
 195 * This only updates the "non-critical" parts of the directory
 196 * cache, ie the parts that aren't tracked by GIT, and only used
 197 * to validate the cache.
 198 */
 199void fill_stat_cache_info(struct cache_entry *ce, struct stat *st)
 200{
 201        fill_stat_data(&ce->ce_stat_data, st);
 202
 203        if (assume_unchanged)
 204                ce->ce_flags |= CE_VALID;
 205
 206        if (S_ISREG(st->st_mode)) {
 207                ce_mark_uptodate(ce);
 208                mark_fsmonitor_valid(ce);
 209        }
 210}
 211
 212static int ce_compare_data(struct index_state *istate,
 213                           const struct cache_entry *ce,
 214                           struct stat *st)
 215{
 216        int match = -1;
 217        int fd = git_open_cloexec(ce->name, O_RDONLY);
 218
 219        if (fd >= 0) {
 220                struct object_id oid;
 221                if (!index_fd(istate, &oid, fd, st, OBJ_BLOB, ce->name, 0))
 222                        match = !oideq(&oid, &ce->oid);
 223                /* index_fd() closed the file descriptor already */
 224        }
 225        return match;
 226}
 227
 228static int ce_compare_link(const struct cache_entry *ce, size_t expected_size)
 229{
 230        int match = -1;
 231        void *buffer;
 232        unsigned long size;
 233        enum object_type type;
 234        struct strbuf sb = STRBUF_INIT;
 235
 236        if (strbuf_readlink(&sb, ce->name, expected_size))
 237                return -1;
 238
 239        buffer = read_object_file(&ce->oid, &type, &size);
 240        if (buffer) {
 241                if (size == sb.len)
 242                        match = memcmp(buffer, sb.buf, size);
 243                free(buffer);
 244        }
 245        strbuf_release(&sb);
 246        return match;
 247}
 248
 249static int ce_compare_gitlink(const struct cache_entry *ce)
 250{
 251        struct object_id oid;
 252
 253        /*
 254         * We don't actually require that the .git directory
 255         * under GITLINK directory be a valid git directory. It
 256         * might even be missing (in case nobody populated that
 257         * sub-project).
 258         *
 259         * If so, we consider it always to match.
 260         */
 261        if (resolve_gitlink_ref(ce->name, "HEAD", &oid) < 0)
 262                return 0;
 263        return !oideq(&oid, &ce->oid);
 264}
 265
 266static int ce_modified_check_fs(struct index_state *istate,
 267                                const struct cache_entry *ce,
 268                                struct stat *st)
 269{
 270        switch (st->st_mode & S_IFMT) {
 271        case S_IFREG:
 272                if (ce_compare_data(istate, ce, st))
 273                        return DATA_CHANGED;
 274                break;
 275        case S_IFLNK:
 276                if (ce_compare_link(ce, xsize_t(st->st_size)))
 277                        return DATA_CHANGED;
 278                break;
 279        case S_IFDIR:
 280                if (S_ISGITLINK(ce->ce_mode))
 281                        return ce_compare_gitlink(ce) ? DATA_CHANGED : 0;
 282                /* else fallthrough */
 283        default:
 284                return TYPE_CHANGED;
 285        }
 286        return 0;
 287}
 288
 289static int ce_match_stat_basic(const struct cache_entry *ce, struct stat *st)
 290{
 291        unsigned int changed = 0;
 292
 293        if (ce->ce_flags & CE_REMOVE)
 294                return MODE_CHANGED | DATA_CHANGED | TYPE_CHANGED;
 295
 296        switch (ce->ce_mode & S_IFMT) {
 297        case S_IFREG:
 298                changed |= !S_ISREG(st->st_mode) ? TYPE_CHANGED : 0;
 299                /* We consider only the owner x bit to be relevant for
 300                 * "mode changes"
 301                 */
 302                if (trust_executable_bit &&
 303                    (0100 & (ce->ce_mode ^ st->st_mode)))
 304                        changed |= MODE_CHANGED;
 305                break;
 306        case S_IFLNK:
 307                if (!S_ISLNK(st->st_mode) &&
 308                    (has_symlinks || !S_ISREG(st->st_mode)))
 309                        changed |= TYPE_CHANGED;
 310                break;
 311        case S_IFGITLINK:
 312                /* We ignore most of the st_xxx fields for gitlinks */
 313                if (!S_ISDIR(st->st_mode))
 314                        changed |= TYPE_CHANGED;
 315                else if (ce_compare_gitlink(ce))
 316                        changed |= DATA_CHANGED;
 317                return changed;
 318        default:
 319                die("internal error: ce_mode is %o", ce->ce_mode);
 320        }
 321
 322        changed |= match_stat_data(&ce->ce_stat_data, st);
 323
 324        /* Racily smudged entry? */
 325        if (!ce->ce_stat_data.sd_size) {
 326                if (!is_empty_blob_sha1(ce->oid.hash))
 327                        changed |= DATA_CHANGED;
 328        }
 329
 330        return changed;
 331}
 332
 333static int is_racy_stat(const struct index_state *istate,
 334                        const struct stat_data *sd)
 335{
 336        return (istate->timestamp.sec &&
 337#ifdef USE_NSEC
 338                 /* nanosecond timestamped files can also be racy! */
 339                (istate->timestamp.sec < sd->sd_mtime.sec ||
 340                 (istate->timestamp.sec == sd->sd_mtime.sec &&
 341                  istate->timestamp.nsec <= sd->sd_mtime.nsec))
 342#else
 343                istate->timestamp.sec <= sd->sd_mtime.sec
 344#endif
 345                );
 346}
 347
 348int is_racy_timestamp(const struct index_state *istate,
 349                             const struct cache_entry *ce)
 350{
 351        return (!S_ISGITLINK(ce->ce_mode) &&
 352                is_racy_stat(istate, &ce->ce_stat_data));
 353}
 354
 355int match_stat_data_racy(const struct index_state *istate,
 356                         const struct stat_data *sd, struct stat *st)
 357{
 358        if (is_racy_stat(istate, sd))
 359                return MTIME_CHANGED;
 360        return match_stat_data(sd, st);
 361}
 362
 363int ie_match_stat(struct index_state *istate,
 364                  const struct cache_entry *ce, struct stat *st,
 365                  unsigned int options)
 366{
 367        unsigned int changed;
 368        int ignore_valid = options & CE_MATCH_IGNORE_VALID;
 369        int ignore_skip_worktree = options & CE_MATCH_IGNORE_SKIP_WORKTREE;
 370        int assume_racy_is_modified = options & CE_MATCH_RACY_IS_DIRTY;
 371        int ignore_fsmonitor = options & CE_MATCH_IGNORE_FSMONITOR;
 372
 373        if (!ignore_fsmonitor)
 374                refresh_fsmonitor(istate);
 375        /*
 376         * If it's marked as always valid in the index, it's
 377         * valid whatever the checked-out copy says.
 378         *
 379         * skip-worktree has the same effect with higher precedence
 380         */
 381        if (!ignore_skip_worktree && ce_skip_worktree(ce))
 382                return 0;
 383        if (!ignore_valid && (ce->ce_flags & CE_VALID))
 384                return 0;
 385        if (!ignore_fsmonitor && (ce->ce_flags & CE_FSMONITOR_VALID))
 386                return 0;
 387
 388        /*
 389         * Intent-to-add entries have not been added, so the index entry
 390         * by definition never matches what is in the work tree until it
 391         * actually gets added.
 392         */
 393        if (ce_intent_to_add(ce))
 394                return DATA_CHANGED | TYPE_CHANGED | MODE_CHANGED;
 395
 396        changed = ce_match_stat_basic(ce, st);
 397
 398        /*
 399         * Within 1 second of this sequence:
 400         *      echo xyzzy >file && git-update-index --add file
 401         * running this command:
 402         *      echo frotz >file
 403         * would give a falsely clean cache entry.  The mtime and
 404         * length match the cache, and other stat fields do not change.
 405         *
 406         * We could detect this at update-index time (the cache entry
 407         * being registered/updated records the same time as "now")
 408         * and delay the return from git-update-index, but that would
 409         * effectively mean we can make at most one commit per second,
 410         * which is not acceptable.  Instead, we check cache entries
 411         * whose mtime are the same as the index file timestamp more
 412         * carefully than others.
 413         */
 414        if (!changed && is_racy_timestamp(istate, ce)) {
 415                if (assume_racy_is_modified)
 416                        changed |= DATA_CHANGED;
 417                else
 418                        changed |= ce_modified_check_fs(istate, ce, st);
 419        }
 420
 421        return changed;
 422}
 423
 424int ie_modified(struct index_state *istate,
 425                const struct cache_entry *ce,
 426                struct stat *st, unsigned int options)
 427{
 428        int changed, changed_fs;
 429
 430        changed = ie_match_stat(istate, ce, st, options);
 431        if (!changed)
 432                return 0;
 433        /*
 434         * If the mode or type has changed, there's no point in trying
 435         * to refresh the entry - it's not going to match
 436         */
 437        if (changed & (MODE_CHANGED | TYPE_CHANGED))
 438                return changed;
 439
 440        /*
 441         * Immediately after read-tree or update-index --cacheinfo,
 442         * the length field is zero, as we have never even read the
 443         * lstat(2) information once, and we cannot trust DATA_CHANGED
 444         * returned by ie_match_stat() which in turn was returned by
 445         * ce_match_stat_basic() to signal that the filesize of the
 446         * blob changed.  We have to actually go to the filesystem to
 447         * see if the contents match, and if so, should answer "unchanged".
 448         *
 449         * The logic does not apply to gitlinks, as ce_match_stat_basic()
 450         * already has checked the actual HEAD from the filesystem in the
 451         * subproject.  If ie_match_stat() already said it is different,
 452         * then we know it is.
 453         */
 454        if ((changed & DATA_CHANGED) &&
 455            (S_ISGITLINK(ce->ce_mode) || ce->ce_stat_data.sd_size != 0))
 456                return changed;
 457
 458        changed_fs = ce_modified_check_fs(istate, ce, st);
 459        if (changed_fs)
 460                return changed | changed_fs;
 461        return 0;
 462}
 463
 464int base_name_compare(const char *name1, int len1, int mode1,
 465                      const char *name2, int len2, int mode2)
 466{
 467        unsigned char c1, c2;
 468        int len = len1 < len2 ? len1 : len2;
 469        int cmp;
 470
 471        cmp = memcmp(name1, name2, len);
 472        if (cmp)
 473                return cmp;
 474        c1 = name1[len];
 475        c2 = name2[len];
 476        if (!c1 && S_ISDIR(mode1))
 477                c1 = '/';
 478        if (!c2 && S_ISDIR(mode2))
 479                c2 = '/';
 480        return (c1 < c2) ? -1 : (c1 > c2) ? 1 : 0;
 481}
 482
 483/*
 484 * df_name_compare() is identical to base_name_compare(), except it
 485 * compares conflicting directory/file entries as equal. Note that
 486 * while a directory name compares as equal to a regular file, they
 487 * then individually compare _differently_ to a filename that has
 488 * a dot after the basename (because '\0' < '.' < '/').
 489 *
 490 * This is used by routines that want to traverse the git namespace
 491 * but then handle conflicting entries together when possible.
 492 */
 493int df_name_compare(const char *name1, int len1, int mode1,
 494                    const char *name2, int len2, int mode2)
 495{
 496        int len = len1 < len2 ? len1 : len2, cmp;
 497        unsigned char c1, c2;
 498
 499        cmp = memcmp(name1, name2, len);
 500        if (cmp)
 501                return cmp;
 502        /* Directories and files compare equal (same length, same name) */
 503        if (len1 == len2)
 504                return 0;
 505        c1 = name1[len];
 506        if (!c1 && S_ISDIR(mode1))
 507                c1 = '/';
 508        c2 = name2[len];
 509        if (!c2 && S_ISDIR(mode2))
 510                c2 = '/';
 511        if (c1 == '/' && !c2)
 512                return 0;
 513        if (c2 == '/' && !c1)
 514                return 0;
 515        return c1 - c2;
 516}
 517
 518int name_compare(const char *name1, size_t len1, const char *name2, size_t len2)
 519{
 520        size_t min_len = (len1 < len2) ? len1 : len2;
 521        int cmp = memcmp(name1, name2, min_len);
 522        if (cmp)
 523                return cmp;
 524        if (len1 < len2)
 525                return -1;
 526        if (len1 > len2)
 527                return 1;
 528        return 0;
 529}
 530
 531int cache_name_stage_compare(const char *name1, int len1, int stage1, const char *name2, int len2, int stage2)
 532{
 533        int cmp;
 534
 535        cmp = name_compare(name1, len1, name2, len2);
 536        if (cmp)
 537                return cmp;
 538
 539        if (stage1 < stage2)
 540                return -1;
 541        if (stage1 > stage2)
 542                return 1;
 543        return 0;
 544}
 545
 546static int index_name_stage_pos(const struct index_state *istate, const char *name, int namelen, int stage)
 547{
 548        int first, last;
 549
 550        first = 0;
 551        last = istate->cache_nr;
 552        while (last > first) {
 553                int next = (last + first) >> 1;
 554                struct cache_entry *ce = istate->cache[next];
 555                int cmp = cache_name_stage_compare(name, namelen, stage, ce->name, ce_namelen(ce), ce_stage(ce));
 556                if (!cmp)
 557                        return next;
 558                if (cmp < 0) {
 559                        last = next;
 560                        continue;
 561                }
 562                first = next+1;
 563        }
 564        return -first-1;
 565}
 566
 567int index_name_pos(const struct index_state *istate, const char *name, int namelen)
 568{
 569        return index_name_stage_pos(istate, name, namelen, 0);
 570}
 571
 572int remove_index_entry_at(struct index_state *istate, int pos)
 573{
 574        struct cache_entry *ce = istate->cache[pos];
 575
 576        record_resolve_undo(istate, ce);
 577        remove_name_hash(istate, ce);
 578        save_or_free_index_entry(istate, ce);
 579        istate->cache_changed |= CE_ENTRY_REMOVED;
 580        istate->cache_nr--;
 581        if (pos >= istate->cache_nr)
 582                return 0;
 583        MOVE_ARRAY(istate->cache + pos, istate->cache + pos + 1,
 584                   istate->cache_nr - pos);
 585        return 1;
 586}
 587
 588/*
 589 * Remove all cache entries marked for removal, that is where
 590 * CE_REMOVE is set in ce_flags.  This is much more effective than
 591 * calling remove_index_entry_at() for each entry to be removed.
 592 */
 593void remove_marked_cache_entries(struct index_state *istate)
 594{
 595        struct cache_entry **ce_array = istate->cache;
 596        unsigned int i, j;
 597
 598        for (i = j = 0; i < istate->cache_nr; i++) {
 599                if (ce_array[i]->ce_flags & CE_REMOVE) {
 600                        remove_name_hash(istate, ce_array[i]);
 601                        save_or_free_index_entry(istate, ce_array[i]);
 602                }
 603                else
 604                        ce_array[j++] = ce_array[i];
 605        }
 606        if (j == istate->cache_nr)
 607                return;
 608        istate->cache_changed |= CE_ENTRY_REMOVED;
 609        istate->cache_nr = j;
 610}
 611
 612int remove_file_from_index(struct index_state *istate, const char *path)
 613{
 614        int pos = index_name_pos(istate, path, strlen(path));
 615        if (pos < 0)
 616                pos = -pos-1;
 617        cache_tree_invalidate_path(istate, path);
 618        untracked_cache_remove_from_index(istate, path);
 619        while (pos < istate->cache_nr && !strcmp(istate->cache[pos]->name, path))
 620                remove_index_entry_at(istate, pos);
 621        return 0;
 622}
 623
 624static int compare_name(struct cache_entry *ce, const char *path, int namelen)
 625{
 626        return namelen != ce_namelen(ce) || memcmp(path, ce->name, namelen);
 627}
 628
 629static int index_name_pos_also_unmerged(struct index_state *istate,
 630        const char *path, int namelen)
 631{
 632        int pos = index_name_pos(istate, path, namelen);
 633        struct cache_entry *ce;
 634
 635        if (pos >= 0)
 636                return pos;
 637
 638        /* maybe unmerged? */
 639        pos = -1 - pos;
 640        if (pos >= istate->cache_nr ||
 641                        compare_name((ce = istate->cache[pos]), path, namelen))
 642                return -1;
 643
 644        /* order of preference: stage 2, 1, 3 */
 645        if (ce_stage(ce) == 1 && pos + 1 < istate->cache_nr &&
 646                        ce_stage((ce = istate->cache[pos + 1])) == 2 &&
 647                        !compare_name(ce, path, namelen))
 648                pos++;
 649        return pos;
 650}
 651
 652static int different_name(struct cache_entry *ce, struct cache_entry *alias)
 653{
 654        int len = ce_namelen(ce);
 655        return ce_namelen(alias) != len || memcmp(ce->name, alias->name, len);
 656}
 657
 658/*
 659 * If we add a filename that aliases in the cache, we will use the
 660 * name that we already have - but we don't want to update the same
 661 * alias twice, because that implies that there were actually two
 662 * different files with aliasing names!
 663 *
 664 * So we use the CE_ADDED flag to verify that the alias was an old
 665 * one before we accept it as
 666 */
 667static struct cache_entry *create_alias_ce(struct index_state *istate,
 668                                           struct cache_entry *ce,
 669                                           struct cache_entry *alias)
 670{
 671        int len;
 672        struct cache_entry *new_entry;
 673
 674        if (alias->ce_flags & CE_ADDED)
 675                die("Will not add file alias '%s' ('%s' already exists in index)", ce->name, alias->name);
 676
 677        /* Ok, create the new entry using the name of the existing alias */
 678        len = ce_namelen(alias);
 679        new_entry = make_empty_cache_entry(istate, len);
 680        memcpy(new_entry->name, alias->name, len);
 681        copy_cache_entry(new_entry, ce);
 682        save_or_free_index_entry(istate, ce);
 683        return new_entry;
 684}
 685
 686void set_object_name_for_intent_to_add_entry(struct cache_entry *ce)
 687{
 688        struct object_id oid;
 689        if (write_object_file("", 0, blob_type, &oid))
 690                die("cannot create an empty blob in the object database");
 691        oidcpy(&ce->oid, &oid);
 692}
 693
 694int add_to_index(struct index_state *istate, const char *path, struct stat *st, int flags)
 695{
 696        int namelen, was_same;
 697        mode_t st_mode = st->st_mode;
 698        struct cache_entry *ce, *alias = NULL;
 699        unsigned ce_option = CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE|CE_MATCH_RACY_IS_DIRTY;
 700        int verbose = flags & (ADD_CACHE_VERBOSE | ADD_CACHE_PRETEND);
 701        int pretend = flags & ADD_CACHE_PRETEND;
 702        int intent_only = flags & ADD_CACHE_INTENT;
 703        int add_option = (ADD_CACHE_OK_TO_ADD|ADD_CACHE_OK_TO_REPLACE|
 704                          (intent_only ? ADD_CACHE_NEW_ONLY : 0));
 705        int newflags = HASH_WRITE_OBJECT;
 706
 707        if (flags & HASH_RENORMALIZE)
 708                newflags |= HASH_RENORMALIZE;
 709
 710        if (!S_ISREG(st_mode) && !S_ISLNK(st_mode) && !S_ISDIR(st_mode))
 711                return error("%s: can only add regular files, symbolic links or git-directories", path);
 712
 713        namelen = strlen(path);
 714        if (S_ISDIR(st_mode)) {
 715                while (namelen && path[namelen-1] == '/')
 716                        namelen--;
 717        }
 718        ce = make_empty_cache_entry(istate, namelen);
 719        memcpy(ce->name, path, namelen);
 720        ce->ce_namelen = namelen;
 721        if (!intent_only)
 722                fill_stat_cache_info(ce, st);
 723        else
 724                ce->ce_flags |= CE_INTENT_TO_ADD;
 725
 726
 727        if (trust_executable_bit && has_symlinks) {
 728                ce->ce_mode = create_ce_mode(st_mode);
 729        } else {
 730                /* If there is an existing entry, pick the mode bits and type
 731                 * from it, otherwise assume unexecutable regular file.
 732                 */
 733                struct cache_entry *ent;
 734                int pos = index_name_pos_also_unmerged(istate, path, namelen);
 735
 736                ent = (0 <= pos) ? istate->cache[pos] : NULL;
 737                ce->ce_mode = ce_mode_from_stat(ent, st_mode);
 738        }
 739
 740        /* When core.ignorecase=true, determine if a directory of the same name but differing
 741         * case already exists within the Git repository.  If it does, ensure the directory
 742         * case of the file being added to the repository matches (is folded into) the existing
 743         * entry's directory case.
 744         */
 745        if (ignore_case) {
 746                adjust_dirname_case(istate, ce->name);
 747        }
 748        if (!(flags & HASH_RENORMALIZE)) {
 749                alias = index_file_exists(istate, ce->name,
 750                                          ce_namelen(ce), ignore_case);
 751                if (alias &&
 752                    !ce_stage(alias) &&
 753                    !ie_match_stat(istate, alias, st, ce_option)) {
 754                        /* Nothing changed, really */
 755                        if (!S_ISGITLINK(alias->ce_mode))
 756                                ce_mark_uptodate(alias);
 757                        alias->ce_flags |= CE_ADDED;
 758
 759                        discard_cache_entry(ce);
 760                        return 0;
 761                }
 762        }
 763        if (!intent_only) {
 764                if (index_path(istate, &ce->oid, path, st, newflags)) {
 765                        discard_cache_entry(ce);
 766                        return error("unable to index file %s", path);
 767                }
 768        } else
 769                set_object_name_for_intent_to_add_entry(ce);
 770
 771        if (ignore_case && alias && different_name(ce, alias))
 772                ce = create_alias_ce(istate, ce, alias);
 773        ce->ce_flags |= CE_ADDED;
 774
 775        /* It was suspected to be racily clean, but it turns out to be Ok */
 776        was_same = (alias &&
 777                    !ce_stage(alias) &&
 778                    oideq(&alias->oid, &ce->oid) &&
 779                    ce->ce_mode == alias->ce_mode);
 780
 781        if (pretend)
 782                discard_cache_entry(ce);
 783        else if (add_index_entry(istate, ce, add_option)) {
 784                discard_cache_entry(ce);
 785                return error("unable to add %s to index", path);
 786        }
 787        if (verbose && !was_same)
 788                printf("add '%s'\n", path);
 789        return 0;
 790}
 791
 792int add_file_to_index(struct index_state *istate, const char *path, int flags)
 793{
 794        struct stat st;
 795        if (lstat(path, &st))
 796                die_errno("unable to stat '%s'", path);
 797        return add_to_index(istate, path, &st, flags);
 798}
 799
 800struct cache_entry *make_empty_cache_entry(struct index_state *istate, size_t len)
 801{
 802        return mem_pool__ce_calloc(find_mem_pool(istate), len);
 803}
 804
 805struct cache_entry *make_empty_transient_cache_entry(size_t len)
 806{
 807        return xcalloc(1, cache_entry_size(len));
 808}
 809
 810struct cache_entry *make_cache_entry(struct index_state *istate,
 811                                     unsigned int mode,
 812                                     const struct object_id *oid,
 813                                     const char *path,
 814                                     int stage,
 815                                     unsigned int refresh_options)
 816{
 817        struct cache_entry *ce, *ret;
 818        int len;
 819
 820        if (!verify_path(path, mode)) {
 821                error("Invalid path '%s'", path);
 822                return NULL;
 823        }
 824
 825        len = strlen(path);
 826        ce = make_empty_cache_entry(istate, len);
 827
 828        oidcpy(&ce->oid, oid);
 829        memcpy(ce->name, path, len);
 830        ce->ce_flags = create_ce_flags(stage);
 831        ce->ce_namelen = len;
 832        ce->ce_mode = create_ce_mode(mode);
 833
 834        ret = refresh_cache_entry(istate, ce, refresh_options);
 835        if (ret != ce)
 836                discard_cache_entry(ce);
 837        return ret;
 838}
 839
 840struct cache_entry *make_transient_cache_entry(unsigned int mode, const struct object_id *oid,
 841                                               const char *path, int stage)
 842{
 843        struct cache_entry *ce;
 844        int len;
 845
 846        if (!verify_path(path, mode)) {
 847                error("Invalid path '%s'", path);
 848                return NULL;
 849        }
 850
 851        len = strlen(path);
 852        ce = make_empty_transient_cache_entry(len);
 853
 854        oidcpy(&ce->oid, oid);
 855        memcpy(ce->name, path, len);
 856        ce->ce_flags = create_ce_flags(stage);
 857        ce->ce_namelen = len;
 858        ce->ce_mode = create_ce_mode(mode);
 859
 860        return ce;
 861}
 862
 863/*
 864 * Chmod an index entry with either +x or -x.
 865 *
 866 * Returns -1 if the chmod for the particular cache entry failed (if it's
 867 * not a regular file), -2 if an invalid flip argument is passed in, 0
 868 * otherwise.
 869 */
 870int chmod_index_entry(struct index_state *istate, struct cache_entry *ce,
 871                      char flip)
 872{
 873        if (!S_ISREG(ce->ce_mode))
 874                return -1;
 875        switch (flip) {
 876        case '+':
 877                ce->ce_mode |= 0111;
 878                break;
 879        case '-':
 880                ce->ce_mode &= ~0111;
 881                break;
 882        default:
 883                return -2;
 884        }
 885        cache_tree_invalidate_path(istate, ce->name);
 886        ce->ce_flags |= CE_UPDATE_IN_BASE;
 887        mark_fsmonitor_invalid(istate, ce);
 888        istate->cache_changed |= CE_ENTRY_CHANGED;
 889
 890        return 0;
 891}
 892
 893int ce_same_name(const struct cache_entry *a, const struct cache_entry *b)
 894{
 895        int len = ce_namelen(a);
 896        return ce_namelen(b) == len && !memcmp(a->name, b->name, len);
 897}
 898
 899/*
 900 * We fundamentally don't like some paths: we don't want
 901 * dot or dot-dot anywhere, and for obvious reasons don't
 902 * want to recurse into ".git" either.
 903 *
 904 * Also, we don't want double slashes or slashes at the
 905 * end that can make pathnames ambiguous.
 906 */
 907static int verify_dotfile(const char *rest, unsigned mode)
 908{
 909        /*
 910         * The first character was '.', but that
 911         * has already been discarded, we now test
 912         * the rest.
 913         */
 914
 915        /* "." is not allowed */
 916        if (*rest == '\0' || is_dir_sep(*rest))
 917                return 0;
 918
 919        switch (*rest) {
 920        /*
 921         * ".git" followed by NUL or slash is bad. Note that we match
 922         * case-insensitively here, even if ignore_case is not set.
 923         * This outlaws ".GIT" everywhere out of an abundance of caution,
 924         * since there's really no good reason to allow it.
 925         *
 926         * Once we've seen ".git", we can also find ".gitmodules", etc (also
 927         * case-insensitively).
 928         */
 929        case 'g':
 930        case 'G':
 931                if (rest[1] != 'i' && rest[1] != 'I')
 932                        break;
 933                if (rest[2] != 't' && rest[2] != 'T')
 934                        break;
 935                if (rest[3] == '\0' || is_dir_sep(rest[3]))
 936                        return 0;
 937                if (S_ISLNK(mode)) {
 938                        rest += 3;
 939                        if (skip_iprefix(rest, "modules", &rest) &&
 940                            (*rest == '\0' || is_dir_sep(*rest)))
 941                                return 0;
 942                }
 943                break;
 944        case '.':
 945                if (rest[1] == '\0' || is_dir_sep(rest[1]))
 946                        return 0;
 947        }
 948        return 1;
 949}
 950
 951int verify_path(const char *path, unsigned mode)
 952{
 953        char c;
 954
 955        if (has_dos_drive_prefix(path))
 956                return 0;
 957
 958        goto inside;
 959        for (;;) {
 960                if (!c)
 961                        return 1;
 962                if (is_dir_sep(c)) {
 963inside:
 964                        if (protect_hfs) {
 965                                if (is_hfs_dotgit(path))
 966                                        return 0;
 967                                if (S_ISLNK(mode)) {
 968                                        if (is_hfs_dotgitmodules(path))
 969                                                return 0;
 970                                }
 971                        }
 972                        if (protect_ntfs) {
 973                                if (is_ntfs_dotgit(path))
 974                                        return 0;
 975                                if (S_ISLNK(mode)) {
 976                                        if (is_ntfs_dotgitmodules(path))
 977                                                return 0;
 978                                }
 979                        }
 980
 981                        c = *path++;
 982                        if ((c == '.' && !verify_dotfile(path, mode)) ||
 983                            is_dir_sep(c) || c == '\0')
 984                                return 0;
 985                }
 986                c = *path++;
 987        }
 988}
 989
 990/*
 991 * Do we have another file that has the beginning components being a
 992 * proper superset of the name we're trying to add?
 993 */
 994static int has_file_name(struct index_state *istate,
 995                         const struct cache_entry *ce, int pos, int ok_to_replace)
 996{
 997        int retval = 0;
 998        int len = ce_namelen(ce);
 999        int stage = ce_stage(ce);
1000        const char *name = ce->name;
1001
1002        while (pos < istate->cache_nr) {
1003                struct cache_entry *p = istate->cache[pos++];
1004
1005                if (len >= ce_namelen(p))
1006                        break;
1007                if (memcmp(name, p->name, len))
1008                        break;
1009                if (ce_stage(p) != stage)
1010                        continue;
1011                if (p->name[len] != '/')
1012                        continue;
1013                if (p->ce_flags & CE_REMOVE)
1014                        continue;
1015                retval = -1;
1016                if (!ok_to_replace)
1017                        break;
1018                remove_index_entry_at(istate, --pos);
1019        }
1020        return retval;
1021}
1022
1023
1024/*
1025 * Like strcmp(), but also return the offset of the first change.
1026 * If strings are equal, return the length.
1027 */
1028int strcmp_offset(const char *s1, const char *s2, size_t *first_change)
1029{
1030        size_t k;
1031
1032        if (!first_change)
1033                return strcmp(s1, s2);
1034
1035        for (k = 0; s1[k] == s2[k]; k++)
1036                if (s1[k] == '\0')
1037                        break;
1038
1039        *first_change = k;
1040        return (unsigned char)s1[k] - (unsigned char)s2[k];
1041}
1042
1043/*
1044 * Do we have another file with a pathname that is a proper
1045 * subset of the name we're trying to add?
1046 *
1047 * That is, is there another file in the index with a path
1048 * that matches a sub-directory in the given entry?
1049 */
1050static int has_dir_name(struct index_state *istate,
1051                        const struct cache_entry *ce, int pos, int ok_to_replace)
1052{
1053        int retval = 0;
1054        int stage = ce_stage(ce);
1055        const char *name = ce->name;
1056        const char *slash = name + ce_namelen(ce);
1057        size_t len_eq_last;
1058        int cmp_last = 0;
1059
1060        /*
1061         * We are frequently called during an iteration on a sorted
1062         * list of pathnames and while building a new index.  Therefore,
1063         * there is a high probability that this entry will eventually
1064         * be appended to the index, rather than inserted in the middle.
1065         * If we can confirm that, we can avoid binary searches on the
1066         * components of the pathname.
1067         *
1068         * Compare the entry's full path with the last path in the index.
1069         */
1070        if (istate->cache_nr > 0) {
1071                cmp_last = strcmp_offset(name,
1072                        istate->cache[istate->cache_nr - 1]->name,
1073                        &len_eq_last);
1074                if (cmp_last > 0) {
1075                        if (len_eq_last == 0) {
1076                                /*
1077                                 * The entry sorts AFTER the last one in the
1078                                 * index and their paths have no common prefix,
1079                                 * so there cannot be a F/D conflict.
1080                                 */
1081                                return retval;
1082                        } else {
1083                                /*
1084                                 * The entry sorts AFTER the last one in the
1085                                 * index, but has a common prefix.  Fall through
1086                                 * to the loop below to disect the entry's path
1087                                 * and see where the difference is.
1088                                 */
1089                        }
1090                } else if (cmp_last == 0) {
1091                        /*
1092                         * The entry exactly matches the last one in the
1093                         * index, but because of multiple stage and CE_REMOVE
1094                         * items, we fall through and let the regular search
1095                         * code handle it.
1096                         */
1097                }
1098        }
1099
1100        for (;;) {
1101                size_t len;
1102
1103                for (;;) {
1104                        if (*--slash == '/')
1105                                break;
1106                        if (slash <= ce->name)
1107                                return retval;
1108                }
1109                len = slash - name;
1110
1111                if (cmp_last > 0) {
1112                        /*
1113                         * (len + 1) is a directory boundary (including
1114                         * the trailing slash).  And since the loop is
1115                         * decrementing "slash", the first iteration is
1116                         * the longest directory prefix; subsequent
1117                         * iterations consider parent directories.
1118                         */
1119
1120                        if (len + 1 <= len_eq_last) {
1121                                /*
1122                                 * The directory prefix (including the trailing
1123                                 * slash) also appears as a prefix in the last
1124                                 * entry, so the remainder cannot collide (because
1125                                 * strcmp said the whole path was greater).
1126                                 *
1127                                 * EQ: last: xxx/A
1128                                 *     this: xxx/B
1129                                 *
1130                                 * LT: last: xxx/file_A
1131                                 *     this: xxx/file_B
1132                                 */
1133                                return retval;
1134                        }
1135
1136                        if (len > len_eq_last) {
1137                                /*
1138                                 * This part of the directory prefix (excluding
1139                                 * the trailing slash) is longer than the known
1140                                 * equal portions, so this sub-directory cannot
1141                                 * collide with a file.
1142                                 *
1143                                 * GT: last: xxxA
1144                                 *     this: xxxB/file
1145                                 */
1146                                return retval;
1147                        }
1148
1149                        if (istate->cache_nr > 0 &&
1150                                ce_namelen(istate->cache[istate->cache_nr - 1]) > len) {
1151                                /*
1152                                 * The directory prefix lines up with part of
1153                                 * a longer file or directory name, but sorts
1154                                 * after it, so this sub-directory cannot
1155                                 * collide with a file.
1156                                 *
1157                                 * last: xxx/yy-file (because '-' sorts before '/')
1158                                 * this: xxx/yy/abc
1159                                 */
1160                                return retval;
1161                        }
1162
1163                        /*
1164                         * This is a possible collision. Fall through and
1165                         * let the regular search code handle it.
1166                         *
1167                         * last: xxx
1168                         * this: xxx/file
1169                         */
1170                }
1171
1172                pos = index_name_stage_pos(istate, name, len, stage);
1173                if (pos >= 0) {
1174                        /*
1175                         * Found one, but not so fast.  This could
1176                         * be a marker that says "I was here, but
1177                         * I am being removed".  Such an entry is
1178                         * not a part of the resulting tree, and
1179                         * it is Ok to have a directory at the same
1180                         * path.
1181                         */
1182                        if (!(istate->cache[pos]->ce_flags & CE_REMOVE)) {
1183                                retval = -1;
1184                                if (!ok_to_replace)
1185                                        break;
1186                                remove_index_entry_at(istate, pos);
1187                                continue;
1188                        }
1189                }
1190                else
1191                        pos = -pos-1;
1192
1193                /*
1194                 * Trivial optimization: if we find an entry that
1195                 * already matches the sub-directory, then we know
1196                 * we're ok, and we can exit.
1197                 */
1198                while (pos < istate->cache_nr) {
1199                        struct cache_entry *p = istate->cache[pos];
1200                        if ((ce_namelen(p) <= len) ||
1201                            (p->name[len] != '/') ||
1202                            memcmp(p->name, name, len))
1203                                break; /* not our subdirectory */
1204                        if (ce_stage(p) == stage && !(p->ce_flags & CE_REMOVE))
1205                                /*
1206                                 * p is at the same stage as our entry, and
1207                                 * is a subdirectory of what we are looking
1208                                 * at, so we cannot have conflicts at our
1209                                 * level or anything shorter.
1210                                 */
1211                                return retval;
1212                        pos++;
1213                }
1214        }
1215        return retval;
1216}
1217
1218/* We may be in a situation where we already have path/file and path
1219 * is being added, or we already have path and path/file is being
1220 * added.  Either one would result in a nonsense tree that has path
1221 * twice when git-write-tree tries to write it out.  Prevent it.
1222 *
1223 * If ok-to-replace is specified, we remove the conflicting entries
1224 * from the cache so the caller should recompute the insert position.
1225 * When this happens, we return non-zero.
1226 */
1227static int check_file_directory_conflict(struct index_state *istate,
1228                                         const struct cache_entry *ce,
1229                                         int pos, int ok_to_replace)
1230{
1231        int retval;
1232
1233        /*
1234         * When ce is an "I am going away" entry, we allow it to be added
1235         */
1236        if (ce->ce_flags & CE_REMOVE)
1237                return 0;
1238
1239        /*
1240         * We check if the path is a sub-path of a subsequent pathname
1241         * first, since removing those will not change the position
1242         * in the array.
1243         */
1244        retval = has_file_name(istate, ce, pos, ok_to_replace);
1245
1246        /*
1247         * Then check if the path might have a clashing sub-directory
1248         * before it.
1249         */
1250        return retval + has_dir_name(istate, ce, pos, ok_to_replace);
1251}
1252
1253static int add_index_entry_with_check(struct index_state *istate, struct cache_entry *ce, int option)
1254{
1255        int pos;
1256        int ok_to_add = option & ADD_CACHE_OK_TO_ADD;
1257        int ok_to_replace = option & ADD_CACHE_OK_TO_REPLACE;
1258        int skip_df_check = option & ADD_CACHE_SKIP_DFCHECK;
1259        int new_only = option & ADD_CACHE_NEW_ONLY;
1260
1261        if (!(option & ADD_CACHE_KEEP_CACHE_TREE))
1262                cache_tree_invalidate_path(istate, ce->name);
1263
1264        /*
1265         * If this entry's path sorts after the last entry in the index,
1266         * we can avoid searching for it.
1267         */
1268        if (istate->cache_nr > 0 &&
1269                strcmp(ce->name, istate->cache[istate->cache_nr - 1]->name) > 0)
1270                pos = -istate->cache_nr - 1;
1271        else
1272                pos = index_name_stage_pos(istate, ce->name, ce_namelen(ce), ce_stage(ce));
1273
1274        /* existing match? Just replace it. */
1275        if (pos >= 0) {
1276                if (!new_only)
1277                        replace_index_entry(istate, pos, ce);
1278                return 0;
1279        }
1280        pos = -pos-1;
1281
1282        if (!(option & ADD_CACHE_KEEP_CACHE_TREE))
1283                untracked_cache_add_to_index(istate, ce->name);
1284
1285        /*
1286         * Inserting a merged entry ("stage 0") into the index
1287         * will always replace all non-merged entries..
1288         */
1289        if (pos < istate->cache_nr && ce_stage(ce) == 0) {
1290                while (ce_same_name(istate->cache[pos], ce)) {
1291                        ok_to_add = 1;
1292                        if (!remove_index_entry_at(istate, pos))
1293                                break;
1294                }
1295        }
1296
1297        if (!ok_to_add)
1298                return -1;
1299        if (!verify_path(ce->name, ce->ce_mode))
1300                return error("Invalid path '%s'", ce->name);
1301
1302        if (!skip_df_check &&
1303            check_file_directory_conflict(istate, ce, pos, ok_to_replace)) {
1304                if (!ok_to_replace)
1305                        return error("'%s' appears as both a file and as a directory",
1306                                     ce->name);
1307                pos = index_name_stage_pos(istate, ce->name, ce_namelen(ce), ce_stage(ce));
1308                pos = -pos-1;
1309        }
1310        return pos + 1;
1311}
1312
1313int add_index_entry(struct index_state *istate, struct cache_entry *ce, int option)
1314{
1315        int pos;
1316
1317        if (option & ADD_CACHE_JUST_APPEND)
1318                pos = istate->cache_nr;
1319        else {
1320                int ret;
1321                ret = add_index_entry_with_check(istate, ce, option);
1322                if (ret <= 0)
1323                        return ret;
1324                pos = ret - 1;
1325        }
1326
1327        /* Make sure the array is big enough .. */
1328        ALLOC_GROW(istate->cache, istate->cache_nr + 1, istate->cache_alloc);
1329
1330        /* Add it in.. */
1331        istate->cache_nr++;
1332        if (istate->cache_nr > pos + 1)
1333                MOVE_ARRAY(istate->cache + pos + 1, istate->cache + pos,
1334                           istate->cache_nr - pos - 1);
1335        set_index_entry(istate, pos, ce);
1336        istate->cache_changed |= CE_ENTRY_ADDED;
1337        return 0;
1338}
1339
1340/*
1341 * "refresh" does not calculate a new sha1 file or bring the
1342 * cache up-to-date for mode/content changes. But what it
1343 * _does_ do is to "re-match" the stat information of a file
1344 * with the cache, so that you can refresh the cache for a
1345 * file that hasn't been changed but where the stat entry is
1346 * out of date.
1347 *
1348 * For example, you'd want to do this after doing a "git-read-tree",
1349 * to link up the stat cache details with the proper files.
1350 */
1351static struct cache_entry *refresh_cache_ent(struct index_state *istate,
1352                                             struct cache_entry *ce,
1353                                             unsigned int options, int *err,
1354                                             int *changed_ret)
1355{
1356        struct stat st;
1357        struct cache_entry *updated;
1358        int changed;
1359        int refresh = options & CE_MATCH_REFRESH;
1360        int ignore_valid = options & CE_MATCH_IGNORE_VALID;
1361        int ignore_skip_worktree = options & CE_MATCH_IGNORE_SKIP_WORKTREE;
1362        int ignore_missing = options & CE_MATCH_IGNORE_MISSING;
1363        int ignore_fsmonitor = options & CE_MATCH_IGNORE_FSMONITOR;
1364
1365        if (!refresh || ce_uptodate(ce))
1366                return ce;
1367
1368        if (!ignore_fsmonitor)
1369                refresh_fsmonitor(istate);
1370        /*
1371         * CE_VALID or CE_SKIP_WORKTREE means the user promised us
1372         * that the change to the work tree does not matter and told
1373         * us not to worry.
1374         */
1375        if (!ignore_skip_worktree && ce_skip_worktree(ce)) {
1376                ce_mark_uptodate(ce);
1377                return ce;
1378        }
1379        if (!ignore_valid && (ce->ce_flags & CE_VALID)) {
1380                ce_mark_uptodate(ce);
1381                return ce;
1382        }
1383        if (!ignore_fsmonitor && (ce->ce_flags & CE_FSMONITOR_VALID)) {
1384                ce_mark_uptodate(ce);
1385                return ce;
1386        }
1387
1388        if (has_symlink_leading_path(ce->name, ce_namelen(ce))) {
1389                if (ignore_missing)
1390                        return ce;
1391                if (err)
1392                        *err = ENOENT;
1393                return NULL;
1394        }
1395
1396        if (lstat(ce->name, &st) < 0) {
1397                if (ignore_missing && errno == ENOENT)
1398                        return ce;
1399                if (err)
1400                        *err = errno;
1401                return NULL;
1402        }
1403
1404        changed = ie_match_stat(istate, ce, &st, options);
1405        if (changed_ret)
1406                *changed_ret = changed;
1407        if (!changed) {
1408                /*
1409                 * The path is unchanged.  If we were told to ignore
1410                 * valid bit, then we did the actual stat check and
1411                 * found that the entry is unmodified.  If the entry
1412                 * is not marked VALID, this is the place to mark it
1413                 * valid again, under "assume unchanged" mode.
1414                 */
1415                if (ignore_valid && assume_unchanged &&
1416                    !(ce->ce_flags & CE_VALID))
1417                        ; /* mark this one VALID again */
1418                else {
1419                        /*
1420                         * We do not mark the index itself "modified"
1421                         * because CE_UPTODATE flag is in-core only;
1422                         * we are not going to write this change out.
1423                         */
1424                        if (!S_ISGITLINK(ce->ce_mode)) {
1425                                ce_mark_uptodate(ce);
1426                                mark_fsmonitor_valid(ce);
1427                        }
1428                        return ce;
1429                }
1430        }
1431
1432        if (ie_modified(istate, ce, &st, options)) {
1433                if (err)
1434                        *err = EINVAL;
1435                return NULL;
1436        }
1437
1438        updated = make_empty_cache_entry(istate, ce_namelen(ce));
1439        copy_cache_entry(updated, ce);
1440        memcpy(updated->name, ce->name, ce->ce_namelen + 1);
1441        fill_stat_cache_info(updated, &st);
1442        /*
1443         * If ignore_valid is not set, we should leave CE_VALID bit
1444         * alone.  Otherwise, paths marked with --no-assume-unchanged
1445         * (i.e. things to be edited) will reacquire CE_VALID bit
1446         * automatically, which is not really what we want.
1447         */
1448        if (!ignore_valid && assume_unchanged &&
1449            !(ce->ce_flags & CE_VALID))
1450                updated->ce_flags &= ~CE_VALID;
1451
1452        /* istate->cache_changed is updated in the caller */
1453        return updated;
1454}
1455
1456static void show_file(const char * fmt, const char * name, int in_porcelain,
1457                      int * first, const char *header_msg)
1458{
1459        if (in_porcelain && *first && header_msg) {
1460                printf("%s\n", header_msg);
1461                *first = 0;
1462        }
1463        printf(fmt, name);
1464}
1465
1466int refresh_index(struct index_state *istate, unsigned int flags,
1467                  const struct pathspec *pathspec,
1468                  char *seen, const char *header_msg)
1469{
1470        int i;
1471        int has_errors = 0;
1472        int really = (flags & REFRESH_REALLY) != 0;
1473        int allow_unmerged = (flags & REFRESH_UNMERGED) != 0;
1474        int quiet = (flags & REFRESH_QUIET) != 0;
1475        int not_new = (flags & REFRESH_IGNORE_MISSING) != 0;
1476        int ignore_submodules = (flags & REFRESH_IGNORE_SUBMODULES) != 0;
1477        int first = 1;
1478        int in_porcelain = (flags & REFRESH_IN_PORCELAIN);
1479        unsigned int options = (CE_MATCH_REFRESH |
1480                                (really ? CE_MATCH_IGNORE_VALID : 0) |
1481                                (not_new ? CE_MATCH_IGNORE_MISSING : 0));
1482        const char *modified_fmt;
1483        const char *deleted_fmt;
1484        const char *typechange_fmt;
1485        const char *added_fmt;
1486        const char *unmerged_fmt;
1487        struct progress *progress = NULL;
1488
1489        if (flags & REFRESH_PROGRESS && isatty(2))
1490                progress = start_delayed_progress(_("Refresh index"),
1491                                                  istate->cache_nr);
1492
1493        trace_performance_enter();
1494        modified_fmt = (in_porcelain ? "M\t%s\n" : "%s: needs update\n");
1495        deleted_fmt = (in_porcelain ? "D\t%s\n" : "%s: needs update\n");
1496        typechange_fmt = (in_porcelain ? "T\t%s\n" : "%s needs update\n");
1497        added_fmt = (in_porcelain ? "A\t%s\n" : "%s needs update\n");
1498        unmerged_fmt = (in_porcelain ? "U\t%s\n" : "%s: needs merge\n");
1499        for (i = 0; i < istate->cache_nr; i++) {
1500                struct cache_entry *ce, *new_entry;
1501                int cache_errno = 0;
1502                int changed = 0;
1503                int filtered = 0;
1504
1505                ce = istate->cache[i];
1506                if (ignore_submodules && S_ISGITLINK(ce->ce_mode))
1507                        continue;
1508
1509                if (pathspec && !ce_path_match(istate, ce, pathspec, seen))
1510                        filtered = 1;
1511
1512                if (ce_stage(ce)) {
1513                        while ((i < istate->cache_nr) &&
1514                               ! strcmp(istate->cache[i]->name, ce->name))
1515                                i++;
1516                        i--;
1517                        if (allow_unmerged)
1518                                continue;
1519                        if (!filtered)
1520                                show_file(unmerged_fmt, ce->name, in_porcelain,
1521                                          &first, header_msg);
1522                        has_errors = 1;
1523                        continue;
1524                }
1525
1526                if (filtered)
1527                        continue;
1528
1529                new_entry = refresh_cache_ent(istate, ce, options, &cache_errno, &changed);
1530                if (new_entry == ce)
1531                        continue;
1532                if (progress)
1533                        display_progress(progress, i);
1534                if (!new_entry) {
1535                        const char *fmt;
1536
1537                        if (really && cache_errno == EINVAL) {
1538                                /* If we are doing --really-refresh that
1539                                 * means the index is not valid anymore.
1540                                 */
1541                                ce->ce_flags &= ~CE_VALID;
1542                                ce->ce_flags |= CE_UPDATE_IN_BASE;
1543                                mark_fsmonitor_invalid(istate, ce);
1544                                istate->cache_changed |= CE_ENTRY_CHANGED;
1545                        }
1546                        if (quiet)
1547                                continue;
1548
1549                        if (cache_errno == ENOENT)
1550                                fmt = deleted_fmt;
1551                        else if (ce_intent_to_add(ce))
1552                                fmt = added_fmt; /* must be before other checks */
1553                        else if (changed & TYPE_CHANGED)
1554                                fmt = typechange_fmt;
1555                        else
1556                                fmt = modified_fmt;
1557                        show_file(fmt,
1558                                  ce->name, in_porcelain, &first, header_msg);
1559                        has_errors = 1;
1560                        continue;
1561                }
1562
1563                replace_index_entry(istate, i, new_entry);
1564        }
1565        if (progress) {
1566                display_progress(progress, istate->cache_nr);
1567                stop_progress(&progress);
1568        }
1569        trace_performance_leave("refresh index");
1570        return has_errors;
1571}
1572
1573struct cache_entry *refresh_cache_entry(struct index_state *istate,
1574                                        struct cache_entry *ce,
1575                                        unsigned int options)
1576{
1577        return refresh_cache_ent(istate, ce, options, NULL, NULL);
1578}
1579
1580
1581/*****************************************************************
1582 * Index File I/O
1583 *****************************************************************/
1584
1585#define INDEX_FORMAT_DEFAULT 3
1586
1587static unsigned int get_index_format_default(void)
1588{
1589        char *envversion = getenv("GIT_INDEX_VERSION");
1590        char *endp;
1591        int value;
1592        unsigned int version = INDEX_FORMAT_DEFAULT;
1593
1594        if (!envversion) {
1595                if (!git_config_get_int("index.version", &value))
1596                        version = value;
1597                if (version < INDEX_FORMAT_LB || INDEX_FORMAT_UB < version) {
1598                        warning(_("index.version set, but the value is invalid.\n"
1599                                  "Using version %i"), INDEX_FORMAT_DEFAULT);
1600                        return INDEX_FORMAT_DEFAULT;
1601                }
1602                return version;
1603        }
1604
1605        version = strtoul(envversion, &endp, 10);
1606        if (*endp ||
1607            version < INDEX_FORMAT_LB || INDEX_FORMAT_UB < version) {
1608                warning(_("GIT_INDEX_VERSION set, but the value is invalid.\n"
1609                          "Using version %i"), INDEX_FORMAT_DEFAULT);
1610                version = INDEX_FORMAT_DEFAULT;
1611        }
1612        return version;
1613}
1614
1615/*
1616 * dev/ino/uid/gid/size are also just tracked to the low 32 bits
1617 * Again - this is just a (very strong in practice) heuristic that
1618 * the inode hasn't changed.
1619 *
1620 * We save the fields in big-endian order to allow using the
1621 * index file over NFS transparently.
1622 */
1623struct ondisk_cache_entry {
1624        struct cache_time ctime;
1625        struct cache_time mtime;
1626        uint32_t dev;
1627        uint32_t ino;
1628        uint32_t mode;
1629        uint32_t uid;
1630        uint32_t gid;
1631        uint32_t size;
1632        unsigned char sha1[20];
1633        uint16_t flags;
1634        char name[FLEX_ARRAY]; /* more */
1635};
1636
1637/*
1638 * This struct is used when CE_EXTENDED bit is 1
1639 * The struct must match ondisk_cache_entry exactly from
1640 * ctime till flags
1641 */
1642struct ondisk_cache_entry_extended {
1643        struct cache_time ctime;
1644        struct cache_time mtime;
1645        uint32_t dev;
1646        uint32_t ino;
1647        uint32_t mode;
1648        uint32_t uid;
1649        uint32_t gid;
1650        uint32_t size;
1651        unsigned char sha1[20];
1652        uint16_t flags;
1653        uint16_t flags2;
1654        char name[FLEX_ARRAY]; /* more */
1655};
1656
1657/* These are only used for v3 or lower */
1658#define align_padding_size(size, len) ((size + (len) + 8) & ~7) - (size + len)
1659#define align_flex_name(STRUCT,len) ((offsetof(struct STRUCT,name) + (len) + 8) & ~7)
1660#define ondisk_cache_entry_size(len) align_flex_name(ondisk_cache_entry,len)
1661#define ondisk_cache_entry_extended_size(len) align_flex_name(ondisk_cache_entry_extended,len)
1662#define ondisk_ce_size(ce) (((ce)->ce_flags & CE_EXTENDED) ? \
1663                            ondisk_cache_entry_extended_size(ce_namelen(ce)) : \
1664                            ondisk_cache_entry_size(ce_namelen(ce)))
1665
1666/* Allow fsck to force verification of the index checksum. */
1667int verify_index_checksum;
1668
1669/* Allow fsck to force verification of the cache entry order. */
1670int verify_ce_order;
1671
1672static int verify_hdr(const struct cache_header *hdr, unsigned long size)
1673{
1674        git_hash_ctx c;
1675        unsigned char hash[GIT_MAX_RAWSZ];
1676        int hdr_version;
1677
1678        if (hdr->hdr_signature != htonl(CACHE_SIGNATURE))
1679                return error("bad signature");
1680        hdr_version = ntohl(hdr->hdr_version);
1681        if (hdr_version < INDEX_FORMAT_LB || INDEX_FORMAT_UB < hdr_version)
1682                return error("bad index version %d", hdr_version);
1683
1684        if (!verify_index_checksum)
1685                return 0;
1686
1687        the_hash_algo->init_fn(&c);
1688        the_hash_algo->update_fn(&c, hdr, size - the_hash_algo->rawsz);
1689        the_hash_algo->final_fn(hash, &c);
1690        if (!hasheq(hash, (unsigned char *)hdr + size - the_hash_algo->rawsz))
1691                return error("bad index file sha1 signature");
1692        return 0;
1693}
1694
1695static int read_index_extension(struct index_state *istate,
1696                                const char *ext, const char *data, unsigned long sz)
1697{
1698        switch (CACHE_EXT(ext)) {
1699        case CACHE_EXT_TREE:
1700                istate->cache_tree = cache_tree_read(data, sz);
1701                break;
1702        case CACHE_EXT_RESOLVE_UNDO:
1703                istate->resolve_undo = resolve_undo_read(data, sz);
1704                break;
1705        case CACHE_EXT_LINK:
1706                if (read_link_extension(istate, data, sz))
1707                        return -1;
1708                break;
1709        case CACHE_EXT_UNTRACKED:
1710                istate->untracked = read_untracked_extension(data, sz);
1711                break;
1712        case CACHE_EXT_FSMONITOR:
1713                read_fsmonitor_extension(istate, data, sz);
1714                break;
1715        case CACHE_EXT_ENDOFINDEXENTRIES:
1716        case CACHE_EXT_INDEXENTRYOFFSETTABLE:
1717                /* already handled in do_read_index() */
1718                break;
1719        default:
1720                if (*ext < 'A' || 'Z' < *ext)
1721                        return error("index uses %.4s extension, which we do not understand",
1722                                     ext);
1723                fprintf(stderr, "ignoring %.4s extension\n", ext);
1724                break;
1725        }
1726        return 0;
1727}
1728
1729int hold_locked_index(struct lock_file *lk, int lock_flags)
1730{
1731        return hold_lock_file_for_update(lk, get_index_file(), lock_flags);
1732}
1733
1734int read_index(struct index_state *istate)
1735{
1736        return read_index_from(istate, get_index_file(), get_git_dir());
1737}
1738
1739static struct cache_entry *create_from_disk(struct mem_pool *ce_mem_pool,
1740                                            unsigned int version,
1741                                            struct ondisk_cache_entry *ondisk,
1742                                            unsigned long *ent_size,
1743                                            const struct cache_entry *previous_ce)
1744{
1745        struct cache_entry *ce;
1746        size_t len;
1747        const char *name;
1748        unsigned int flags;
1749        size_t copy_len;
1750        /*
1751         * Adjacent cache entries tend to share the leading paths, so it makes
1752         * sense to only store the differences in later entries.  In the v4
1753         * on-disk format of the index, each on-disk cache entry stores the
1754         * number of bytes to be stripped from the end of the previous name,
1755         * and the bytes to append to the result, to come up with its name.
1756         */
1757        int expand_name_field = version == 4;
1758
1759        /* On-disk flags are just 16 bits */
1760        flags = get_be16(&ondisk->flags);
1761        len = flags & CE_NAMEMASK;
1762
1763        if (flags & CE_EXTENDED) {
1764                struct ondisk_cache_entry_extended *ondisk2;
1765                int extended_flags;
1766                ondisk2 = (struct ondisk_cache_entry_extended *)ondisk;
1767                extended_flags = get_be16(&ondisk2->flags2) << 16;
1768                /* We do not yet understand any bit out of CE_EXTENDED_FLAGS */
1769                if (extended_flags & ~CE_EXTENDED_FLAGS)
1770                        die("Unknown index entry format %08x", extended_flags);
1771                flags |= extended_flags;
1772                name = ondisk2->name;
1773        }
1774        else
1775                name = ondisk->name;
1776
1777        if (expand_name_field) {
1778                const unsigned char *cp = (const unsigned char *)name;
1779                size_t strip_len, previous_len;
1780
1781                /* If we're at the begining of a block, ignore the previous name */
1782                strip_len = decode_varint(&cp);
1783                if (previous_ce) {
1784                        previous_len = previous_ce->ce_namelen;
1785                        if (previous_len < strip_len)
1786                                die(_("malformed name field in the index, near path '%s'"),
1787                                        previous_ce->name);
1788                        copy_len = previous_len - strip_len;
1789                } else {
1790                        copy_len = 0;
1791                }
1792                name = (const char *)cp;
1793        }
1794
1795        if (len == CE_NAMEMASK) {
1796                len = strlen(name);
1797                if (expand_name_field)
1798                        len += copy_len;
1799        }
1800
1801        ce = mem_pool__ce_alloc(ce_mem_pool, len);
1802
1803        ce->ce_stat_data.sd_ctime.sec = get_be32(&ondisk->ctime.sec);
1804        ce->ce_stat_data.sd_mtime.sec = get_be32(&ondisk->mtime.sec);
1805        ce->ce_stat_data.sd_ctime.nsec = get_be32(&ondisk->ctime.nsec);
1806        ce->ce_stat_data.sd_mtime.nsec = get_be32(&ondisk->mtime.nsec);
1807        ce->ce_stat_data.sd_dev   = get_be32(&ondisk->dev);
1808        ce->ce_stat_data.sd_ino   = get_be32(&ondisk->ino);
1809        ce->ce_mode  = get_be32(&ondisk->mode);
1810        ce->ce_stat_data.sd_uid   = get_be32(&ondisk->uid);
1811        ce->ce_stat_data.sd_gid   = get_be32(&ondisk->gid);
1812        ce->ce_stat_data.sd_size  = get_be32(&ondisk->size);
1813        ce->ce_flags = flags & ~CE_NAMEMASK;
1814        ce->ce_namelen = len;
1815        ce->index = 0;
1816        hashcpy(ce->oid.hash, ondisk->sha1);
1817
1818        if (expand_name_field) {
1819                if (copy_len)
1820                        memcpy(ce->name, previous_ce->name, copy_len);
1821                memcpy(ce->name + copy_len, name, len + 1 - copy_len);
1822                *ent_size = (name - ((char *)ondisk)) + len + 1 - copy_len;
1823        } else {
1824                memcpy(ce->name, name, len + 1);
1825                *ent_size = ondisk_ce_size(ce);
1826        }
1827        return ce;
1828}
1829
1830static void check_ce_order(struct index_state *istate)
1831{
1832        unsigned int i;
1833
1834        if (!verify_ce_order)
1835                return;
1836
1837        for (i = 1; i < istate->cache_nr; i++) {
1838                struct cache_entry *ce = istate->cache[i - 1];
1839                struct cache_entry *next_ce = istate->cache[i];
1840                int name_compare = strcmp(ce->name, next_ce->name);
1841
1842                if (0 < name_compare)
1843                        die("unordered stage entries in index");
1844                if (!name_compare) {
1845                        if (!ce_stage(ce))
1846                                die("multiple stage entries for merged file '%s'",
1847                                    ce->name);
1848                        if (ce_stage(ce) > ce_stage(next_ce))
1849                                die("unordered stage entries for '%s'",
1850                                    ce->name);
1851                }
1852        }
1853}
1854
1855static void tweak_untracked_cache(struct index_state *istate)
1856{
1857        switch (git_config_get_untracked_cache()) {
1858        case -1: /* keep: do nothing */
1859                break;
1860        case 0: /* false */
1861                remove_untracked_cache(istate);
1862                break;
1863        case 1: /* true */
1864                add_untracked_cache(istate);
1865                break;
1866        default: /* unknown value: do nothing */
1867                break;
1868        }
1869}
1870
1871static void tweak_split_index(struct index_state *istate)
1872{
1873        switch (git_config_get_split_index()) {
1874        case -1: /* unset: do nothing */
1875                break;
1876        case 0: /* false */
1877                remove_split_index(istate);
1878                break;
1879        case 1: /* true */
1880                add_split_index(istate);
1881                break;
1882        default: /* unknown value: do nothing */
1883                break;
1884        }
1885}
1886
1887static void post_read_index_from(struct index_state *istate)
1888{
1889        check_ce_order(istate);
1890        tweak_untracked_cache(istate);
1891        tweak_split_index(istate);
1892        tweak_fsmonitor(istate);
1893}
1894
1895static size_t estimate_cache_size_from_compressed(unsigned int entries)
1896{
1897        return entries * (sizeof(struct cache_entry) + CACHE_ENTRY_PATH_LENGTH);
1898}
1899
1900static size_t estimate_cache_size(size_t ondisk_size, unsigned int entries)
1901{
1902        long per_entry = sizeof(struct cache_entry) - sizeof(struct ondisk_cache_entry);
1903
1904        /*
1905         * Account for potential alignment differences.
1906         */
1907        per_entry += align_padding_size(sizeof(struct cache_entry), -sizeof(struct ondisk_cache_entry));
1908        return ondisk_size + entries * per_entry;
1909}
1910
1911struct index_entry_offset
1912{
1913        /* starting byte offset into index file, count of index entries in this block */
1914        int offset, nr;
1915};
1916
1917struct index_entry_offset_table
1918{
1919        int nr;
1920        struct index_entry_offset entries[FLEX_ARRAY];
1921};
1922
1923#ifndef NO_PTHREADS
1924static struct index_entry_offset_table *read_ieot_extension(const char *mmap, size_t mmap_size, size_t offset);
1925static void write_ieot_extension(struct strbuf *sb, struct index_entry_offset_table *ieot);
1926#endif
1927
1928static size_t read_eoie_extension(const char *mmap, size_t mmap_size);
1929static void write_eoie_extension(struct strbuf *sb, git_hash_ctx *eoie_context, size_t offset);
1930
1931struct load_index_extensions
1932{
1933#ifndef NO_PTHREADS
1934        pthread_t pthread;
1935#endif
1936        struct index_state *istate;
1937        const char *mmap;
1938        size_t mmap_size;
1939        unsigned long src_offset;
1940};
1941
1942static void *load_index_extensions(void *_data)
1943{
1944        struct load_index_extensions *p = _data;
1945        unsigned long src_offset = p->src_offset;
1946
1947        while (src_offset <= p->mmap_size - the_hash_algo->rawsz - 8) {
1948                /* After an array of active_nr index entries,
1949                 * there can be arbitrary number of extended
1950                 * sections, each of which is prefixed with
1951                 * extension name (4-byte) and section length
1952                 * in 4-byte network byte order.
1953                 */
1954                uint32_t extsize = get_be32(p->mmap + src_offset + 4);
1955                if (read_index_extension(p->istate,
1956                                         p->mmap + src_offset,
1957                                         p->mmap + src_offset + 8,
1958                                         extsize) < 0) {
1959                        munmap((void *)p->mmap, p->mmap_size);
1960                        die(_("index file corrupt"));
1961                }
1962                src_offset += 8;
1963                src_offset += extsize;
1964        }
1965
1966        return NULL;
1967}
1968
1969/*
1970 * A helper function that will load the specified range of cache entries
1971 * from the memory mapped file and add them to the given index.
1972 */
1973static unsigned long load_cache_entry_block(struct index_state *istate,
1974                        struct mem_pool *ce_mem_pool, int offset, int nr, const char *mmap,
1975                        unsigned long start_offset, const struct cache_entry *previous_ce)
1976{
1977        int i;
1978        unsigned long src_offset = start_offset;
1979
1980        for (i = offset; i < offset + nr; i++) {
1981                struct ondisk_cache_entry *disk_ce;
1982                struct cache_entry *ce;
1983                unsigned long consumed;
1984
1985                disk_ce = (struct ondisk_cache_entry *)(mmap + src_offset);
1986                ce = create_from_disk(ce_mem_pool, istate->version, disk_ce, &consumed, previous_ce);
1987                set_index_entry(istate, i, ce);
1988
1989                src_offset += consumed;
1990                previous_ce = ce;
1991        }
1992        return src_offset - start_offset;
1993}
1994
1995static unsigned long load_all_cache_entries(struct index_state *istate,
1996                        const char *mmap, size_t mmap_size, unsigned long src_offset)
1997{
1998        unsigned long consumed;
1999
2000        if (istate->version == 4) {
2001                mem_pool_init(&istate->ce_mem_pool,
2002                                estimate_cache_size_from_compressed(istate->cache_nr));
2003        } else {
2004                mem_pool_init(&istate->ce_mem_pool,
2005                                estimate_cache_size(mmap_size, istate->cache_nr));
2006        }
2007
2008        consumed = load_cache_entry_block(istate, istate->ce_mem_pool,
2009                                        0, istate->cache_nr, mmap, src_offset, NULL);
2010        return consumed;
2011}
2012
2013#ifndef NO_PTHREADS
2014
2015/*
2016 * Mostly randomly chosen maximum thread counts: we
2017 * cap the parallelism to online_cpus() threads, and we want
2018 * to have at least 10000 cache entries per thread for it to
2019 * be worth starting a thread.
2020 */
2021
2022#define THREAD_COST             (10000)
2023
2024struct load_cache_entries_thread_data
2025{
2026        pthread_t pthread;
2027        struct index_state *istate;
2028        struct mem_pool *ce_mem_pool;
2029        int offset;
2030        const char *mmap;
2031        struct index_entry_offset_table *ieot;
2032        int ieot_start;         /* starting index into the ieot array */
2033        int ieot_blocks;        /* count of ieot entries to process */
2034        unsigned long consumed; /* return # of bytes in index file processed */
2035};
2036
2037/*
2038 * A thread proc to run the load_cache_entries() computation
2039 * across multiple background threads.
2040 */
2041static void *load_cache_entries_thread(void *_data)
2042{
2043        struct load_cache_entries_thread_data *p = _data;
2044        int i;
2045
2046        /* iterate across all ieot blocks assigned to this thread */
2047        for (i = p->ieot_start; i < p->ieot_start + p->ieot_blocks; i++) {
2048                p->consumed += load_cache_entry_block(p->istate, p->ce_mem_pool,
2049                        p->offset, p->ieot->entries[i].nr, p->mmap, p->ieot->entries[i].offset, NULL);
2050                p->offset += p->ieot->entries[i].nr;
2051        }
2052        return NULL;
2053}
2054
2055static unsigned long load_cache_entries_threaded(struct index_state *istate, const char *mmap, size_t mmap_size,
2056                        unsigned long src_offset, int nr_threads, struct index_entry_offset_table *ieot)
2057{
2058        int i, offset, ieot_blocks, ieot_start, err;
2059        struct load_cache_entries_thread_data *data;
2060        unsigned long consumed = 0;
2061
2062        /* a little sanity checking */
2063        if (istate->name_hash_initialized)
2064                BUG("the name hash isn't thread safe");
2065
2066        mem_pool_init(&istate->ce_mem_pool, 0);
2067
2068        /* ensure we have no more threads than we have blocks to process */
2069        if (nr_threads > ieot->nr)
2070                nr_threads = ieot->nr;
2071        data = xcalloc(nr_threads, sizeof(*data));
2072
2073        offset = ieot_start = 0;
2074        ieot_blocks = DIV_ROUND_UP(ieot->nr, nr_threads);
2075        for (i = 0; i < nr_threads; i++) {
2076                struct load_cache_entries_thread_data *p = &data[i];
2077                int nr, j;
2078
2079                if (ieot_start + ieot_blocks > ieot->nr)
2080                        ieot_blocks = ieot->nr - ieot_start;
2081
2082                p->istate = istate;
2083                p->offset = offset;
2084                p->mmap = mmap;
2085                p->ieot = ieot;
2086                p->ieot_start = ieot_start;
2087                p->ieot_blocks = ieot_blocks;
2088
2089                /* create a mem_pool for each thread */
2090                nr = 0;
2091                for (j = p->ieot_start; j < p->ieot_start + p->ieot_blocks; j++)
2092                        nr += p->ieot->entries[j].nr;
2093                if (istate->version == 4) {
2094                        mem_pool_init(&p->ce_mem_pool,
2095                                estimate_cache_size_from_compressed(nr));
2096                } else {
2097                        mem_pool_init(&p->ce_mem_pool,
2098                                estimate_cache_size(mmap_size, nr));
2099                }
2100
2101                err = pthread_create(&p->pthread, NULL, load_cache_entries_thread, p);
2102                if (err)
2103                        die(_("unable to create load_cache_entries thread: %s"), strerror(err));
2104
2105                /* increment by the number of cache entries in the ieot block being processed */
2106                for (j = 0; j < ieot_blocks; j++)
2107                        offset += ieot->entries[ieot_start + j].nr;
2108                ieot_start += ieot_blocks;
2109        }
2110
2111        for (i = 0; i < nr_threads; i++) {
2112                struct load_cache_entries_thread_data *p = &data[i];
2113
2114                err = pthread_join(p->pthread, NULL);
2115                if (err)
2116                        die(_("unable to join load_cache_entries thread: %s"), strerror(err));
2117                mem_pool_combine(istate->ce_mem_pool, p->ce_mem_pool);
2118                consumed += p->consumed;
2119        }
2120
2121        free(data);
2122
2123        return consumed;
2124}
2125#endif
2126
2127/* remember to discard_cache() before reading a different cache! */
2128int do_read_index(struct index_state *istate, const char *path, int must_exist)
2129{
2130        int fd;
2131        struct stat st;
2132        unsigned long src_offset;
2133        const struct cache_header *hdr;
2134        const char *mmap;
2135        size_t mmap_size;
2136        struct load_index_extensions p;
2137        size_t extension_offset = 0;
2138#ifndef NO_PTHREADS
2139        int nr_threads, cpus;
2140        struct index_entry_offset_table *ieot = NULL;
2141#endif
2142
2143        if (istate->initialized)
2144                return istate->cache_nr;
2145
2146        istate->timestamp.sec = 0;
2147        istate->timestamp.nsec = 0;
2148        fd = open(path, O_RDONLY);
2149        if (fd < 0) {
2150                if (!must_exist && errno == ENOENT)
2151                        return 0;
2152                die_errno("%s: index file open failed", path);
2153        }
2154
2155        if (fstat(fd, &st))
2156                die_errno("cannot stat the open index");
2157
2158        mmap_size = xsize_t(st.st_size);
2159        if (mmap_size < sizeof(struct cache_header) + the_hash_algo->rawsz)
2160                die("index file smaller than expected");
2161
2162        mmap = xmmap(NULL, mmap_size, PROT_READ, MAP_PRIVATE, fd, 0);
2163        if (mmap == MAP_FAILED)
2164                die_errno("unable to map index file");
2165        close(fd);
2166
2167        hdr = (const struct cache_header *)mmap;
2168        if (verify_hdr(hdr, mmap_size) < 0)
2169                goto unmap;
2170
2171        hashcpy(istate->oid.hash, (const unsigned char *)hdr + mmap_size - the_hash_algo->rawsz);
2172        istate->version = ntohl(hdr->hdr_version);
2173        istate->cache_nr = ntohl(hdr->hdr_entries);
2174        istate->cache_alloc = alloc_nr(istate->cache_nr);
2175        istate->cache = xcalloc(istate->cache_alloc, sizeof(*istate->cache));
2176        istate->initialized = 1;
2177
2178        p.istate = istate;
2179        p.mmap = mmap;
2180        p.mmap_size = mmap_size;
2181
2182        src_offset = sizeof(*hdr);
2183
2184#ifndef NO_PTHREADS
2185        nr_threads = git_config_get_index_threads();
2186
2187        /* TODO: does creating more threads than cores help? */
2188        if (!nr_threads) {
2189                nr_threads = istate->cache_nr / THREAD_COST;
2190                cpus = online_cpus();
2191                if (nr_threads > cpus)
2192                        nr_threads = cpus;
2193        }
2194
2195        if (nr_threads > 1) {
2196                extension_offset = read_eoie_extension(mmap, mmap_size);
2197                if (extension_offset) {
2198                        int err;
2199
2200                        p.src_offset = extension_offset;
2201                        err = pthread_create(&p.pthread, NULL, load_index_extensions, &p);
2202                        if (err)
2203                                die(_("unable to create load_index_extensions thread: %s"), strerror(err));
2204
2205                        nr_threads--;
2206                }
2207        }
2208
2209        /*
2210         * Locate and read the index entry offset table so that we can use it
2211         * to multi-thread the reading of the cache entries.
2212         */
2213        if (extension_offset && nr_threads > 1)
2214                ieot = read_ieot_extension(mmap, mmap_size, extension_offset);
2215
2216        if (ieot) {
2217                src_offset += load_cache_entries_threaded(istate, mmap, mmap_size, src_offset, nr_threads, ieot);
2218                free(ieot);
2219        } else {
2220                src_offset += load_all_cache_entries(istate, mmap, mmap_size, src_offset);
2221        }
2222#else
2223        src_offset += load_all_cache_entries(istate, mmap, mmap_size, src_offset);
2224#endif
2225
2226        istate->timestamp.sec = st.st_mtime;
2227        istate->timestamp.nsec = ST_MTIME_NSEC(st);
2228
2229        /* if we created a thread, join it otherwise load the extensions on the primary thread */
2230#ifndef NO_PTHREADS
2231        if (extension_offset) {
2232                int ret = pthread_join(p.pthread, NULL);
2233                if (ret)
2234                        die(_("unable to join load_index_extensions thread: %s"), strerror(ret));
2235        }
2236#endif
2237        if (!extension_offset) {
2238                p.src_offset = src_offset;
2239                load_index_extensions(&p);
2240        }
2241        munmap((void *)mmap, mmap_size);
2242        return istate->cache_nr;
2243
2244unmap:
2245        munmap((void *)mmap, mmap_size);
2246        die("index file corrupt");
2247}
2248
2249/*
2250 * Signal that the shared index is used by updating its mtime.
2251 *
2252 * This way, shared index can be removed if they have not been used
2253 * for some time.
2254 */
2255static void freshen_shared_index(const char *shared_index, int warn)
2256{
2257        if (!check_and_freshen_file(shared_index, 1) && warn)
2258                warning("could not freshen shared index '%s'", shared_index);
2259}
2260
2261int read_index_from(struct index_state *istate, const char *path,
2262                    const char *gitdir)
2263{
2264        struct split_index *split_index;
2265        int ret;
2266        char *base_oid_hex;
2267        char *base_path;
2268
2269        /* istate->initialized covers both .git/index and .git/sharedindex.xxx */
2270        if (istate->initialized)
2271                return istate->cache_nr;
2272
2273        trace_performance_enter();
2274        ret = do_read_index(istate, path, 0);
2275        trace_performance_leave("read cache %s", path);
2276
2277        split_index = istate->split_index;
2278        if (!split_index || is_null_oid(&split_index->base_oid)) {
2279                post_read_index_from(istate);
2280                return ret;
2281        }
2282
2283        trace_performance_enter();
2284        if (split_index->base)
2285                discard_index(split_index->base);
2286        else
2287                split_index->base = xcalloc(1, sizeof(*split_index->base));
2288
2289        base_oid_hex = oid_to_hex(&split_index->base_oid);
2290        base_path = xstrfmt("%s/sharedindex.%s", gitdir, base_oid_hex);
2291        ret = do_read_index(split_index->base, base_path, 1);
2292        if (!oideq(&split_index->base_oid, &split_index->base->oid))
2293                die("broken index, expect %s in %s, got %s",
2294                    base_oid_hex, base_path,
2295                    oid_to_hex(&split_index->base->oid));
2296
2297        freshen_shared_index(base_path, 0);
2298        merge_base_index(istate);
2299        post_read_index_from(istate);
2300        trace_performance_leave("read cache %s", base_path);
2301        free(base_path);
2302        return ret;
2303}
2304
2305int is_index_unborn(struct index_state *istate)
2306{
2307        return (!istate->cache_nr && !istate->timestamp.sec);
2308}
2309
2310int discard_index(struct index_state *istate)
2311{
2312        /*
2313         * Cache entries in istate->cache[] should have been allocated
2314         * from the memory pool associated with this index, or from an
2315         * associated split_index. There is no need to free individual
2316         * cache entries. validate_cache_entries can detect when this
2317         * assertion does not hold.
2318         */
2319        validate_cache_entries(istate);
2320
2321        resolve_undo_clear_index(istate);
2322        istate->cache_nr = 0;
2323        istate->cache_changed = 0;
2324        istate->timestamp.sec = 0;
2325        istate->timestamp.nsec = 0;
2326        free_name_hash(istate);
2327        cache_tree_free(&(istate->cache_tree));
2328        istate->initialized = 0;
2329        FREE_AND_NULL(istate->cache);
2330        istate->cache_alloc = 0;
2331        discard_split_index(istate);
2332        free_untracked_cache(istate->untracked);
2333        istate->untracked = NULL;
2334
2335        if (istate->ce_mem_pool) {
2336                mem_pool_discard(istate->ce_mem_pool, should_validate_cache_entries());
2337                istate->ce_mem_pool = NULL;
2338        }
2339
2340        return 0;
2341}
2342
2343/*
2344 * Validate the cache entries of this index.
2345 * All cache entries associated with this index
2346 * should have been allocated by the memory pool
2347 * associated with this index, or by a referenced
2348 * split index.
2349 */
2350void validate_cache_entries(const struct index_state *istate)
2351{
2352        int i;
2353
2354        if (!should_validate_cache_entries() ||!istate || !istate->initialized)
2355                return;
2356
2357        for (i = 0; i < istate->cache_nr; i++) {
2358                if (!istate) {
2359                        die("internal error: cache entry is not allocated from expected memory pool");
2360                } else if (!istate->ce_mem_pool ||
2361                        !mem_pool_contains(istate->ce_mem_pool, istate->cache[i])) {
2362                        if (!istate->split_index ||
2363                                !istate->split_index->base ||
2364                                !istate->split_index->base->ce_mem_pool ||
2365                                !mem_pool_contains(istate->split_index->base->ce_mem_pool, istate->cache[i])) {
2366                                die("internal error: cache entry is not allocated from expected memory pool");
2367                        }
2368                }
2369        }
2370
2371        if (istate->split_index)
2372                validate_cache_entries(istate->split_index->base);
2373}
2374
2375int unmerged_index(const struct index_state *istate)
2376{
2377        int i;
2378        for (i = 0; i < istate->cache_nr; i++) {
2379                if (ce_stage(istate->cache[i]))
2380                        return 1;
2381        }
2382        return 0;
2383}
2384
2385int index_has_changes(struct index_state *istate,
2386                      struct tree *tree,
2387                      struct strbuf *sb)
2388{
2389        struct object_id cmp;
2390        int i;
2391
2392        if (istate != &the_index) {
2393                BUG("index_has_changes cannot yet accept istate != &the_index; do_diff_cache needs updating first.");
2394        }
2395        if (tree)
2396                cmp = tree->object.oid;
2397        if (tree || !get_oid_tree("HEAD", &cmp)) {
2398                struct diff_options opt;
2399
2400                repo_diff_setup(the_repository, &opt);
2401                opt.flags.exit_with_status = 1;
2402                if (!sb)
2403                        opt.flags.quick = 1;
2404                do_diff_cache(&cmp, &opt);
2405                diffcore_std(&opt);
2406                for (i = 0; sb && i < diff_queued_diff.nr; i++) {
2407                        if (i)
2408                                strbuf_addch(sb, ' ');
2409                        strbuf_addstr(sb, diff_queued_diff.queue[i]->two->path);
2410                }
2411                diff_flush(&opt);
2412                return opt.flags.has_changes != 0;
2413        } else {
2414                for (i = 0; sb && i < istate->cache_nr; i++) {
2415                        if (i)
2416                                strbuf_addch(sb, ' ');
2417                        strbuf_addstr(sb, istate->cache[i]->name);
2418                }
2419                return !!istate->cache_nr;
2420        }
2421}
2422
2423#define WRITE_BUFFER_SIZE 8192
2424static unsigned char write_buffer[WRITE_BUFFER_SIZE];
2425static unsigned long write_buffer_len;
2426
2427static int ce_write_flush(git_hash_ctx *context, int fd)
2428{
2429        unsigned int buffered = write_buffer_len;
2430        if (buffered) {
2431                the_hash_algo->update_fn(context, write_buffer, buffered);
2432                if (write_in_full(fd, write_buffer, buffered) < 0)
2433                        return -1;
2434                write_buffer_len = 0;
2435        }
2436        return 0;
2437}
2438
2439static int ce_write(git_hash_ctx *context, int fd, void *data, unsigned int len)
2440{
2441        while (len) {
2442                unsigned int buffered = write_buffer_len;
2443                unsigned int partial = WRITE_BUFFER_SIZE - buffered;
2444                if (partial > len)
2445                        partial = len;
2446                memcpy(write_buffer + buffered, data, partial);
2447                buffered += partial;
2448                if (buffered == WRITE_BUFFER_SIZE) {
2449                        write_buffer_len = buffered;
2450                        if (ce_write_flush(context, fd))
2451                                return -1;
2452                        buffered = 0;
2453                }
2454                write_buffer_len = buffered;
2455                len -= partial;
2456                data = (char *) data + partial;
2457        }
2458        return 0;
2459}
2460
2461static int write_index_ext_header(git_hash_ctx *context, git_hash_ctx *eoie_context,
2462                                  int fd, unsigned int ext, unsigned int sz)
2463{
2464        ext = htonl(ext);
2465        sz = htonl(sz);
2466        if (eoie_context) {
2467                the_hash_algo->update_fn(eoie_context, &ext, 4);
2468                the_hash_algo->update_fn(eoie_context, &sz, 4);
2469        }
2470        return ((ce_write(context, fd, &ext, 4) < 0) ||
2471                (ce_write(context, fd, &sz, 4) < 0)) ? -1 : 0;
2472}
2473
2474static int ce_flush(git_hash_ctx *context, int fd, unsigned char *hash)
2475{
2476        unsigned int left = write_buffer_len;
2477
2478        if (left) {
2479                write_buffer_len = 0;
2480                the_hash_algo->update_fn(context, write_buffer, left);
2481        }
2482
2483        /* Flush first if not enough space for hash signature */
2484        if (left + the_hash_algo->rawsz > WRITE_BUFFER_SIZE) {
2485                if (write_in_full(fd, write_buffer, left) < 0)
2486                        return -1;
2487                left = 0;
2488        }
2489
2490        /* Append the hash signature at the end */
2491        the_hash_algo->final_fn(write_buffer + left, context);
2492        hashcpy(hash, write_buffer + left);
2493        left += the_hash_algo->rawsz;
2494        return (write_in_full(fd, write_buffer, left) < 0) ? -1 : 0;
2495}
2496
2497static void ce_smudge_racily_clean_entry(struct index_state *istate,
2498                                         struct cache_entry *ce)
2499{
2500        /*
2501         * The only thing we care about in this function is to smudge the
2502         * falsely clean entry due to touch-update-touch race, so we leave
2503         * everything else as they are.  We are called for entries whose
2504         * ce_stat_data.sd_mtime match the index file mtime.
2505         *
2506         * Note that this actually does not do much for gitlinks, for
2507         * which ce_match_stat_basic() always goes to the actual
2508         * contents.  The caller checks with is_racy_timestamp() which
2509         * always says "no" for gitlinks, so we are not called for them ;-)
2510         */
2511        struct stat st;
2512
2513        if (lstat(ce->name, &st) < 0)
2514                return;
2515        if (ce_match_stat_basic(ce, &st))
2516                return;
2517        if (ce_modified_check_fs(istate, ce, &st)) {
2518                /* This is "racily clean"; smudge it.  Note that this
2519                 * is a tricky code.  At first glance, it may appear
2520                 * that it can break with this sequence:
2521                 *
2522                 * $ echo xyzzy >frotz
2523                 * $ git-update-index --add frotz
2524                 * $ : >frotz
2525                 * $ sleep 3
2526                 * $ echo filfre >nitfol
2527                 * $ git-update-index --add nitfol
2528                 *
2529                 * but it does not.  When the second update-index runs,
2530                 * it notices that the entry "frotz" has the same timestamp
2531                 * as index, and if we were to smudge it by resetting its
2532                 * size to zero here, then the object name recorded
2533                 * in index is the 6-byte file but the cached stat information
2534                 * becomes zero --- which would then match what we would
2535                 * obtain from the filesystem next time we stat("frotz").
2536                 *
2537                 * However, the second update-index, before calling
2538                 * this function, notices that the cached size is 6
2539                 * bytes and what is on the filesystem is an empty
2540                 * file, and never calls us, so the cached size information
2541                 * for "frotz" stays 6 which does not match the filesystem.
2542                 */
2543                ce->ce_stat_data.sd_size = 0;
2544        }
2545}
2546
2547/* Copy miscellaneous fields but not the name */
2548static void copy_cache_entry_to_ondisk(struct ondisk_cache_entry *ondisk,
2549                                       struct cache_entry *ce)
2550{
2551        short flags;
2552
2553        ondisk->ctime.sec = htonl(ce->ce_stat_data.sd_ctime.sec);
2554        ondisk->mtime.sec = htonl(ce->ce_stat_data.sd_mtime.sec);
2555        ondisk->ctime.nsec = htonl(ce->ce_stat_data.sd_ctime.nsec);
2556        ondisk->mtime.nsec = htonl(ce->ce_stat_data.sd_mtime.nsec);
2557        ondisk->dev  = htonl(ce->ce_stat_data.sd_dev);
2558        ondisk->ino  = htonl(ce->ce_stat_data.sd_ino);
2559        ondisk->mode = htonl(ce->ce_mode);
2560        ondisk->uid  = htonl(ce->ce_stat_data.sd_uid);
2561        ondisk->gid  = htonl(ce->ce_stat_data.sd_gid);
2562        ondisk->size = htonl(ce->ce_stat_data.sd_size);
2563        hashcpy(ondisk->sha1, ce->oid.hash);
2564
2565        flags = ce->ce_flags & ~CE_NAMEMASK;
2566        flags |= (ce_namelen(ce) >= CE_NAMEMASK ? CE_NAMEMASK : ce_namelen(ce));
2567        ondisk->flags = htons(flags);
2568        if (ce->ce_flags & CE_EXTENDED) {
2569                struct ondisk_cache_entry_extended *ondisk2;
2570                ondisk2 = (struct ondisk_cache_entry_extended *)ondisk;
2571                ondisk2->flags2 = htons((ce->ce_flags & CE_EXTENDED_FLAGS) >> 16);
2572        }
2573}
2574
2575static int ce_write_entry(git_hash_ctx *c, int fd, struct cache_entry *ce,
2576                          struct strbuf *previous_name, struct ondisk_cache_entry *ondisk)
2577{
2578        int size;
2579        int result;
2580        unsigned int saved_namelen;
2581        int stripped_name = 0;
2582        static unsigned char padding[8] = { 0x00 };
2583
2584        if (ce->ce_flags & CE_STRIP_NAME) {
2585                saved_namelen = ce_namelen(ce);
2586                ce->ce_namelen = 0;
2587                stripped_name = 1;
2588        }
2589
2590        if (ce->ce_flags & CE_EXTENDED)
2591                size = offsetof(struct ondisk_cache_entry_extended, name);
2592        else
2593                size = offsetof(struct ondisk_cache_entry, name);
2594
2595        if (!previous_name) {
2596                int len = ce_namelen(ce);
2597                copy_cache_entry_to_ondisk(ondisk, ce);
2598                result = ce_write(c, fd, ondisk, size);
2599                if (!result)
2600                        result = ce_write(c, fd, ce->name, len);
2601                if (!result)
2602                        result = ce_write(c, fd, padding, align_padding_size(size, len));
2603        } else {
2604                int common, to_remove, prefix_size;
2605                unsigned char to_remove_vi[16];
2606                for (common = 0;
2607                     (ce->name[common] &&
2608                      common < previous_name->len &&
2609                      ce->name[common] == previous_name->buf[common]);
2610                     common++)
2611                        ; /* still matching */
2612                to_remove = previous_name->len - common;
2613                prefix_size = encode_varint(to_remove, to_remove_vi);
2614
2615                copy_cache_entry_to_ondisk(ondisk, ce);
2616                result = ce_write(c, fd, ondisk, size);
2617                if (!result)
2618                        result = ce_write(c, fd, to_remove_vi, prefix_size);
2619                if (!result)
2620                        result = ce_write(c, fd, ce->name + common, ce_namelen(ce) - common);
2621                if (!result)
2622                        result = ce_write(c, fd, padding, 1);
2623
2624                strbuf_splice(previous_name, common, to_remove,
2625                              ce->name + common, ce_namelen(ce) - common);
2626        }
2627        if (stripped_name) {
2628                ce->ce_namelen = saved_namelen;
2629                ce->ce_flags &= ~CE_STRIP_NAME;
2630        }
2631
2632        return result;
2633}
2634
2635/*
2636 * This function verifies if index_state has the correct sha1 of the
2637 * index file.  Don't die if we have any other failure, just return 0.
2638 */
2639static int verify_index_from(const struct index_state *istate, const char *path)
2640{
2641        int fd;
2642        ssize_t n;
2643        struct stat st;
2644        unsigned char hash[GIT_MAX_RAWSZ];
2645
2646        if (!istate->initialized)
2647                return 0;
2648
2649        fd = open(path, O_RDONLY);
2650        if (fd < 0)
2651                return 0;
2652
2653        if (fstat(fd, &st))
2654                goto out;
2655
2656        if (st.st_size < sizeof(struct cache_header) + the_hash_algo->rawsz)
2657                goto out;
2658
2659        n = pread_in_full(fd, hash, the_hash_algo->rawsz, st.st_size - the_hash_algo->rawsz);
2660        if (n != the_hash_algo->rawsz)
2661                goto out;
2662
2663        if (!hasheq(istate->oid.hash, hash))
2664                goto out;
2665
2666        close(fd);
2667        return 1;
2668
2669out:
2670        close(fd);
2671        return 0;
2672}
2673
2674static int verify_index(const struct index_state *istate)
2675{
2676        return verify_index_from(istate, get_index_file());
2677}
2678
2679static int has_racy_timestamp(struct index_state *istate)
2680{
2681        int entries = istate->cache_nr;
2682        int i;
2683
2684        for (i = 0; i < entries; i++) {
2685                struct cache_entry *ce = istate->cache[i];
2686                if (is_racy_timestamp(istate, ce))
2687                        return 1;
2688        }
2689        return 0;
2690}
2691
2692void update_index_if_able(struct index_state *istate, struct lock_file *lockfile)
2693{
2694        if ((istate->cache_changed || has_racy_timestamp(istate)) &&
2695            verify_index(istate))
2696                write_locked_index(istate, lockfile, COMMIT_LOCK);
2697        else
2698                rollback_lock_file(lockfile);
2699}
2700
2701/*
2702 * On success, `tempfile` is closed. If it is the temporary file
2703 * of a `struct lock_file`, we will therefore effectively perform
2704 * a 'close_lock_file_gently()`. Since that is an implementation
2705 * detail of lockfiles, callers of `do_write_index()` should not
2706 * rely on it.
2707 */
2708static int do_write_index(struct index_state *istate, struct tempfile *tempfile,
2709                          int strip_extensions)
2710{
2711        uint64_t start = getnanotime();
2712        int newfd = tempfile->fd;
2713        git_hash_ctx c, eoie_c;
2714        struct cache_header hdr;
2715        int i, err = 0, removed, extended, hdr_version;
2716        struct cache_entry **cache = istate->cache;
2717        int entries = istate->cache_nr;
2718        struct stat st;
2719        struct ondisk_cache_entry_extended ondisk;
2720        struct strbuf previous_name_buf = STRBUF_INIT, *previous_name;
2721        int drop_cache_tree = istate->drop_cache_tree;
2722        off_t offset;
2723        int ieot_entries = 1;
2724        struct index_entry_offset_table *ieot = NULL;
2725        int nr, nr_threads;
2726
2727        for (i = removed = extended = 0; i < entries; i++) {
2728                if (cache[i]->ce_flags & CE_REMOVE)
2729                        removed++;
2730
2731                /* reduce extended entries if possible */
2732                cache[i]->ce_flags &= ~CE_EXTENDED;
2733                if (cache[i]->ce_flags & CE_EXTENDED_FLAGS) {
2734                        extended++;
2735                        cache[i]->ce_flags |= CE_EXTENDED;
2736                }
2737        }
2738
2739        if (!istate->version) {
2740                istate->version = get_index_format_default();
2741                if (git_env_bool("GIT_TEST_SPLIT_INDEX", 0))
2742                        init_split_index(istate);
2743        }
2744
2745        /* demote version 3 to version 2 when the latter suffices */
2746        if (istate->version == 3 || istate->version == 2)
2747                istate->version = extended ? 3 : 2;
2748
2749        hdr_version = istate->version;
2750
2751        hdr.hdr_signature = htonl(CACHE_SIGNATURE);
2752        hdr.hdr_version = htonl(hdr_version);
2753        hdr.hdr_entries = htonl(entries - removed);
2754
2755        the_hash_algo->init_fn(&c);
2756        if (ce_write(&c, newfd, &hdr, sizeof(hdr)) < 0)
2757                return -1;
2758
2759#ifndef NO_PTHREADS
2760        nr_threads = git_config_get_index_threads();
2761        if (nr_threads != 1) {
2762                int ieot_blocks, cpus;
2763
2764                /*
2765                 * ensure default number of ieot blocks maps evenly to the
2766                 * default number of threads that will process them leaving
2767                 * room for the thread to load the index extensions.
2768                 */
2769                if (!nr_threads) {
2770                        ieot_blocks = istate->cache_nr / THREAD_COST;
2771                        cpus = online_cpus();
2772                        if (ieot_blocks > cpus - 1)
2773                                ieot_blocks = cpus - 1;
2774                } else {
2775                        ieot_blocks = nr_threads;
2776                        if (ieot_blocks > istate->cache_nr)
2777                                ieot_blocks = istate->cache_nr;
2778                }
2779
2780                /*
2781                 * no reason to write out the IEOT extension if we don't
2782                 * have enough blocks to utilize multi-threading
2783                 */
2784                if (ieot_blocks > 1) {
2785                        ieot = xcalloc(1, sizeof(struct index_entry_offset_table)
2786                                + (ieot_blocks * sizeof(struct index_entry_offset)));
2787                        ieot_entries = DIV_ROUND_UP(entries, ieot_blocks);
2788                }
2789        }
2790#endif
2791
2792        offset = lseek(newfd, 0, SEEK_CUR);
2793        if (offset < 0) {
2794                free(ieot);
2795                return -1;
2796        }
2797        offset += write_buffer_len;
2798        nr = 0;
2799        previous_name = (hdr_version == 4) ? &previous_name_buf : NULL;
2800
2801        for (i = 0; i < entries; i++) {
2802                struct cache_entry *ce = cache[i];
2803                if (ce->ce_flags & CE_REMOVE)
2804                        continue;
2805                if (!ce_uptodate(ce) && is_racy_timestamp(istate, ce))
2806                        ce_smudge_racily_clean_entry(istate, ce);
2807                if (is_null_oid(&ce->oid)) {
2808                        static const char msg[] = "cache entry has null sha1: %s";
2809                        static int allow = -1;
2810
2811                        if (allow < 0)
2812                                allow = git_env_bool("GIT_ALLOW_NULL_SHA1", 0);
2813                        if (allow)
2814                                warning(msg, ce->name);
2815                        else
2816                                err = error(msg, ce->name);
2817
2818                        drop_cache_tree = 1;
2819                }
2820                if (ieot && i && (i % ieot_entries == 0)) {
2821                        ieot->entries[ieot->nr].nr = nr;
2822                        ieot->entries[ieot->nr].offset = offset;
2823                        ieot->nr++;
2824                        /*
2825                         * If we have a V4 index, set the first byte to an invalid
2826                         * character to ensure there is nothing common with the previous
2827                         * entry
2828                         */
2829                        if (previous_name)
2830                                previous_name->buf[0] = 0;
2831                        nr = 0;
2832                        offset = lseek(newfd, 0, SEEK_CUR);
2833                        if (offset < 0) {
2834                                free(ieot);
2835                                return -1;
2836                        }
2837                        offset += write_buffer_len;
2838                }
2839                if (ce_write_entry(&c, newfd, ce, previous_name, (struct ondisk_cache_entry *)&ondisk) < 0)
2840                        err = -1;
2841
2842                if (err)
2843                        break;
2844                nr++;
2845        }
2846        if (ieot && nr) {
2847                ieot->entries[ieot->nr].nr = nr;
2848                ieot->entries[ieot->nr].offset = offset;
2849                ieot->nr++;
2850        }
2851        strbuf_release(&previous_name_buf);
2852
2853        if (err) {
2854                free(ieot);
2855                return err;
2856        }
2857
2858        /* Write extension data here */
2859        offset = lseek(newfd, 0, SEEK_CUR);
2860        if (offset < 0) {
2861                free(ieot);
2862                return -1;
2863        }
2864        offset += write_buffer_len;
2865        the_hash_algo->init_fn(&eoie_c);
2866
2867        /*
2868         * Lets write out CACHE_EXT_INDEXENTRYOFFSETTABLE first so that we
2869         * can minimize the number of extensions we have to scan through to
2870         * find it during load.  Write it out regardless of the
2871         * strip_extensions parameter as we need it when loading the shared
2872         * index.
2873         */
2874#ifndef NO_PTHREADS
2875        if (ieot) {
2876                struct strbuf sb = STRBUF_INIT;
2877
2878                write_ieot_extension(&sb, ieot);
2879                err = write_index_ext_header(&c, &eoie_c, newfd, CACHE_EXT_INDEXENTRYOFFSETTABLE, sb.len) < 0
2880                        || ce_write(&c, newfd, sb.buf, sb.len) < 0;
2881                strbuf_release(&sb);
2882                free(ieot);
2883                if (err)
2884                        return -1;
2885        }
2886#endif
2887
2888        if (!strip_extensions && istate->split_index) {
2889                struct strbuf sb = STRBUF_INIT;
2890
2891                err = write_link_extension(&sb, istate) < 0 ||
2892                        write_index_ext_header(&c, &eoie_c, newfd, CACHE_EXT_LINK,
2893                                               sb.len) < 0 ||
2894                        ce_write(&c, newfd, sb.buf, sb.len) < 0;
2895                strbuf_release(&sb);
2896                if (err)
2897                        return -1;
2898        }
2899        if (!strip_extensions && !drop_cache_tree && istate->cache_tree) {
2900                struct strbuf sb = STRBUF_INIT;
2901
2902                cache_tree_write(&sb, istate->cache_tree);
2903                err = write_index_ext_header(&c, &eoie_c, newfd, CACHE_EXT_TREE, sb.len) < 0
2904                        || ce_write(&c, newfd, sb.buf, sb.len) < 0;
2905                strbuf_release(&sb);
2906                if (err)
2907                        return -1;
2908        }
2909        if (!strip_extensions && istate->resolve_undo) {
2910                struct strbuf sb = STRBUF_INIT;
2911
2912                resolve_undo_write(&sb, istate->resolve_undo);
2913                err = write_index_ext_header(&c, &eoie_c, newfd, CACHE_EXT_RESOLVE_UNDO,
2914                                             sb.len) < 0
2915                        || ce_write(&c, newfd, sb.buf, sb.len) < 0;
2916                strbuf_release(&sb);
2917                if (err)
2918                        return -1;
2919        }
2920        if (!strip_extensions && istate->untracked) {
2921                struct strbuf sb = STRBUF_INIT;
2922
2923                write_untracked_extension(&sb, istate->untracked);
2924                err = write_index_ext_header(&c, &eoie_c, newfd, CACHE_EXT_UNTRACKED,
2925                                             sb.len) < 0 ||
2926                        ce_write(&c, newfd, sb.buf, sb.len) < 0;
2927                strbuf_release(&sb);
2928                if (err)
2929                        return -1;
2930        }
2931        if (!strip_extensions && istate->fsmonitor_last_update) {
2932                struct strbuf sb = STRBUF_INIT;
2933
2934                write_fsmonitor_extension(&sb, istate);
2935                err = write_index_ext_header(&c, &eoie_c, newfd, CACHE_EXT_FSMONITOR, sb.len) < 0
2936                        || ce_write(&c, newfd, sb.buf, sb.len) < 0;
2937                strbuf_release(&sb);
2938                if (err)
2939                        return -1;
2940        }
2941
2942        /*
2943         * CACHE_EXT_ENDOFINDEXENTRIES must be written as the last entry before the SHA1
2944         * so that it can be found and processed before all the index entries are
2945         * read.  Write it out regardless of the strip_extensions parameter as we need it
2946         * when loading the shared index.
2947         */
2948        if (offset) {
2949                struct strbuf sb = STRBUF_INIT;
2950
2951                write_eoie_extension(&sb, &eoie_c, offset);
2952                err = write_index_ext_header(&c, NULL, newfd, CACHE_EXT_ENDOFINDEXENTRIES, sb.len) < 0
2953                        || ce_write(&c, newfd, sb.buf, sb.len) < 0;
2954                strbuf_release(&sb);
2955                if (err)
2956                        return -1;
2957        }
2958
2959        if (ce_flush(&c, newfd, istate->oid.hash))
2960                return -1;
2961        if (close_tempfile_gently(tempfile)) {
2962                error(_("could not close '%s'"), tempfile->filename.buf);
2963                return -1;
2964        }
2965        if (stat(tempfile->filename.buf, &st))
2966                return -1;
2967        istate->timestamp.sec = (unsigned int)st.st_mtime;
2968        istate->timestamp.nsec = ST_MTIME_NSEC(st);
2969        trace_performance_since(start, "write index, changed mask = %x", istate->cache_changed);
2970        return 0;
2971}
2972
2973void set_alternate_index_output(const char *name)
2974{
2975        alternate_index_output = name;
2976}
2977
2978static int commit_locked_index(struct lock_file *lk)
2979{
2980        if (alternate_index_output)
2981                return commit_lock_file_to(lk, alternate_index_output);
2982        else
2983                return commit_lock_file(lk);
2984}
2985
2986static int do_write_locked_index(struct index_state *istate, struct lock_file *lock,
2987                                 unsigned flags)
2988{
2989        int ret = do_write_index(istate, lock->tempfile, 0);
2990        if (ret)
2991                return ret;
2992        if (flags & COMMIT_LOCK)
2993                return commit_locked_index(lock);
2994        return close_lock_file_gently(lock);
2995}
2996
2997static int write_split_index(struct index_state *istate,
2998                             struct lock_file *lock,
2999                             unsigned flags)
3000{
3001        int ret;
3002        prepare_to_write_split_index(istate);
3003        ret = do_write_locked_index(istate, lock, flags);
3004        finish_writing_split_index(istate);
3005        return ret;
3006}
3007
3008static const char *shared_index_expire = "2.weeks.ago";
3009
3010static unsigned long get_shared_index_expire_date(void)
3011{
3012        static unsigned long shared_index_expire_date;
3013        static int shared_index_expire_date_prepared;
3014
3015        if (!shared_index_expire_date_prepared) {
3016                git_config_get_expiry("splitindex.sharedindexexpire",
3017                                      &shared_index_expire);
3018                shared_index_expire_date = approxidate(shared_index_expire);
3019                shared_index_expire_date_prepared = 1;
3020        }
3021
3022        return shared_index_expire_date;
3023}
3024
3025static int should_delete_shared_index(const char *shared_index_path)
3026{
3027        struct stat st;
3028        unsigned long expiration;
3029
3030        /* Check timestamp */
3031        expiration = get_shared_index_expire_date();
3032        if (!expiration)
3033                return 0;
3034        if (stat(shared_index_path, &st))
3035                return error_errno(_("could not stat '%s'"), shared_index_path);
3036        if (st.st_mtime > expiration)
3037                return 0;
3038
3039        return 1;
3040}
3041
3042static int clean_shared_index_files(const char *current_hex)
3043{
3044        struct dirent *de;
3045        DIR *dir = opendir(get_git_dir());
3046
3047        if (!dir)
3048                return error_errno(_("unable to open git dir: %s"), get_git_dir());
3049
3050        while ((de = readdir(dir)) != NULL) {
3051                const char *sha1_hex;
3052                const char *shared_index_path;
3053                if (!skip_prefix(de->d_name, "sharedindex.", &sha1_hex))
3054                        continue;
3055                if (!strcmp(sha1_hex, current_hex))
3056                        continue;
3057                shared_index_path = git_path("%s", de->d_name);
3058                if (should_delete_shared_index(shared_index_path) > 0 &&
3059                    unlink(shared_index_path))
3060                        warning_errno(_("unable to unlink: %s"), shared_index_path);
3061        }
3062        closedir(dir);
3063
3064        return 0;
3065}
3066
3067static int write_shared_index(struct index_state *istate,
3068                              struct tempfile **temp)
3069{
3070        struct split_index *si = istate->split_index;
3071        int ret;
3072
3073        move_cache_to_base_index(istate);
3074        ret = do_write_index(si->base, *temp, 1);
3075        if (ret)
3076                return ret;
3077        ret = adjust_shared_perm(get_tempfile_path(*temp));
3078        if (ret) {
3079                error("cannot fix permission bits on %s", get_tempfile_path(*temp));
3080                return ret;
3081        }
3082        ret = rename_tempfile(temp,
3083                              git_path("sharedindex.%s", oid_to_hex(&si->base->oid)));
3084        if (!ret) {
3085                oidcpy(&si->base_oid, &si->base->oid);
3086                clean_shared_index_files(oid_to_hex(&si->base->oid));
3087        }
3088
3089        return ret;
3090}
3091
3092static const int default_max_percent_split_change = 20;
3093
3094static int too_many_not_shared_entries(struct index_state *istate)
3095{
3096        int i, not_shared = 0;
3097        int max_split = git_config_get_max_percent_split_change();
3098
3099        switch (max_split) {
3100        case -1:
3101                /* not or badly configured: use the default value */
3102                max_split = default_max_percent_split_change;
3103                break;
3104        case 0:
3105                return 1; /* 0% means always write a new shared index */
3106        case 100:
3107                return 0; /* 100% means never write a new shared index */
3108        default:
3109                break; /* just use the configured value */
3110        }
3111
3112        /* Count not shared entries */
3113        for (i = 0; i < istate->cache_nr; i++) {
3114                struct cache_entry *ce = istate->cache[i];
3115                if (!ce->index)
3116                        not_shared++;
3117        }
3118
3119        return (int64_t)istate->cache_nr * max_split < (int64_t)not_shared * 100;
3120}
3121
3122int write_locked_index(struct index_state *istate, struct lock_file *lock,
3123                       unsigned flags)
3124{
3125        int new_shared_index, ret;
3126        struct split_index *si = istate->split_index;
3127
3128        if (git_env_bool("GIT_TEST_CHECK_CACHE_TREE", 0))
3129                cache_tree_verify(istate);
3130
3131        if ((flags & SKIP_IF_UNCHANGED) && !istate->cache_changed) {
3132                if (flags & COMMIT_LOCK)
3133                        rollback_lock_file(lock);
3134                return 0;
3135        }
3136
3137        if (istate->fsmonitor_last_update)
3138                fill_fsmonitor_bitmap(istate);
3139
3140        if (!si || alternate_index_output ||
3141            (istate->cache_changed & ~EXTMASK)) {
3142                if (si)
3143                        oidclr(&si->base_oid);
3144                ret = do_write_locked_index(istate, lock, flags);
3145                goto out;
3146        }
3147
3148        if (git_env_bool("GIT_TEST_SPLIT_INDEX", 0)) {
3149                int v = si->base_oid.hash[0];
3150                if ((v & 15) < 6)
3151                        istate->cache_changed |= SPLIT_INDEX_ORDERED;
3152        }
3153        if (too_many_not_shared_entries(istate))
3154                istate->cache_changed |= SPLIT_INDEX_ORDERED;
3155
3156        new_shared_index = istate->cache_changed & SPLIT_INDEX_ORDERED;
3157
3158        if (new_shared_index) {
3159                struct tempfile *temp;
3160                int saved_errno;
3161
3162                temp = mks_tempfile(git_path("sharedindex_XXXXXX"));
3163                if (!temp) {
3164                        oidclr(&si->base_oid);
3165                        ret = do_write_locked_index(istate, lock, flags);
3166                        goto out;
3167                }
3168                ret = write_shared_index(istate, &temp);
3169
3170                saved_errno = errno;
3171                if (is_tempfile_active(temp))
3172                        delete_tempfile(&temp);
3173                errno = saved_errno;
3174
3175                if (ret)
3176                        goto out;
3177        }
3178
3179        ret = write_split_index(istate, lock, flags);
3180
3181        /* Freshen the shared index only if the split-index was written */
3182        if (!ret && !new_shared_index) {
3183                const char *shared_index = git_path("sharedindex.%s",
3184                                                    oid_to_hex(&si->base_oid));
3185                freshen_shared_index(shared_index, 1);
3186        }
3187
3188out:
3189        if (flags & COMMIT_LOCK)
3190                rollback_lock_file(lock);
3191        return ret;
3192}
3193
3194/*
3195 * Read the index file that is potentially unmerged into given
3196 * index_state, dropping any unmerged entries to stage #0 (potentially
3197 * resulting in a path appearing as both a file and a directory in the
3198 * index; the caller is responsible to clear out the extra entries
3199 * before writing the index to a tree).  Returns true if the index is
3200 * unmerged.  Callers who want to refuse to work from an unmerged
3201 * state can call this and check its return value, instead of calling
3202 * read_cache().
3203 */
3204int read_index_unmerged(struct index_state *istate)
3205{
3206        int i;
3207        int unmerged = 0;
3208
3209        read_index(istate);
3210        for (i = 0; i < istate->cache_nr; i++) {
3211                struct cache_entry *ce = istate->cache[i];
3212                struct cache_entry *new_ce;
3213                int len;
3214
3215                if (!ce_stage(ce))
3216                        continue;
3217                unmerged = 1;
3218                len = ce_namelen(ce);
3219                new_ce = make_empty_cache_entry(istate, len);
3220                memcpy(new_ce->name, ce->name, len);
3221                new_ce->ce_flags = create_ce_flags(0) | CE_CONFLICTED;
3222                new_ce->ce_namelen = len;
3223                new_ce->ce_mode = ce->ce_mode;
3224                if (add_index_entry(istate, new_ce, ADD_CACHE_SKIP_DFCHECK))
3225                        return error("%s: cannot drop to stage #0",
3226                                     new_ce->name);
3227        }
3228        return unmerged;
3229}
3230
3231/*
3232 * Returns 1 if the path is an "other" path with respect to
3233 * the index; that is, the path is not mentioned in the index at all,
3234 * either as a file, a directory with some files in the index,
3235 * or as an unmerged entry.
3236 *
3237 * We helpfully remove a trailing "/" from directories so that
3238 * the output of read_directory can be used as-is.
3239 */
3240int index_name_is_other(const struct index_state *istate, const char *name,
3241                int namelen)
3242{
3243        int pos;
3244        if (namelen && name[namelen - 1] == '/')
3245                namelen--;
3246        pos = index_name_pos(istate, name, namelen);
3247        if (0 <= pos)
3248                return 0;       /* exact match */
3249        pos = -pos - 1;
3250        if (pos < istate->cache_nr) {
3251                struct cache_entry *ce = istate->cache[pos];
3252                if (ce_namelen(ce) == namelen &&
3253                    !memcmp(ce->name, name, namelen))
3254                        return 0; /* Yup, this one exists unmerged */
3255        }
3256        return 1;
3257}
3258
3259void *read_blob_data_from_index(const struct index_state *istate,
3260                                const char *path, unsigned long *size)
3261{
3262        int pos, len;
3263        unsigned long sz;
3264        enum object_type type;
3265        void *data;
3266
3267        len = strlen(path);
3268        pos = index_name_pos(istate, path, len);
3269        if (pos < 0) {
3270                /*
3271                 * We might be in the middle of a merge, in which
3272                 * case we would read stage #2 (ours).
3273                 */
3274                int i;
3275                for (i = -pos - 1;
3276                     (pos < 0 && i < istate->cache_nr &&
3277                      !strcmp(istate->cache[i]->name, path));
3278                     i++)
3279                        if (ce_stage(istate->cache[i]) == 2)
3280                                pos = i;
3281        }
3282        if (pos < 0)
3283                return NULL;
3284        data = read_object_file(&istate->cache[pos]->oid, &type, &sz);
3285        if (!data || type != OBJ_BLOB) {
3286                free(data);
3287                return NULL;
3288        }
3289        if (size)
3290                *size = sz;
3291        return data;
3292}
3293
3294void stat_validity_clear(struct stat_validity *sv)
3295{
3296        FREE_AND_NULL(sv->sd);
3297}
3298
3299int stat_validity_check(struct stat_validity *sv, const char *path)
3300{
3301        struct stat st;
3302
3303        if (stat(path, &st) < 0)
3304                return sv->sd == NULL;
3305        if (!sv->sd)
3306                return 0;
3307        return S_ISREG(st.st_mode) && !match_stat_data(sv->sd, &st);
3308}
3309
3310void stat_validity_update(struct stat_validity *sv, int fd)
3311{
3312        struct stat st;
3313
3314        if (fstat(fd, &st) < 0 || !S_ISREG(st.st_mode))
3315                stat_validity_clear(sv);
3316        else {
3317                if (!sv->sd)
3318                        sv->sd = xcalloc(1, sizeof(struct stat_data));
3319                fill_stat_data(sv->sd, &st);
3320        }
3321}
3322
3323void move_index_extensions(struct index_state *dst, struct index_state *src)
3324{
3325        dst->untracked = src->untracked;
3326        src->untracked = NULL;
3327        dst->cache_tree = src->cache_tree;
3328        src->cache_tree = NULL;
3329}
3330
3331struct cache_entry *dup_cache_entry(const struct cache_entry *ce,
3332                                    struct index_state *istate)
3333{
3334        unsigned int size = ce_size(ce);
3335        int mem_pool_allocated;
3336        struct cache_entry *new_entry = make_empty_cache_entry(istate, ce_namelen(ce));
3337        mem_pool_allocated = new_entry->mem_pool_allocated;
3338
3339        memcpy(new_entry, ce, size);
3340        new_entry->mem_pool_allocated = mem_pool_allocated;
3341        return new_entry;
3342}
3343
3344void discard_cache_entry(struct cache_entry *ce)
3345{
3346        if (ce && should_validate_cache_entries())
3347                memset(ce, 0xCD, cache_entry_size(ce->ce_namelen));
3348
3349        if (ce && ce->mem_pool_allocated)
3350                return;
3351
3352        free(ce);
3353}
3354
3355int should_validate_cache_entries(void)
3356{
3357        static int validate_index_cache_entries = -1;
3358
3359        if (validate_index_cache_entries < 0) {
3360                if (getenv("GIT_TEST_VALIDATE_INDEX_CACHE_ENTRIES"))
3361                        validate_index_cache_entries = 1;
3362                else
3363                        validate_index_cache_entries = 0;
3364        }
3365
3366        return validate_index_cache_entries;
3367}
3368
3369#define EOIE_SIZE (4 + GIT_SHA1_RAWSZ) /* <4-byte offset> + <20-byte hash> */
3370#define EOIE_SIZE_WITH_HEADER (4 + 4 + EOIE_SIZE) /* <4-byte signature> + <4-byte length> + EOIE_SIZE */
3371
3372static size_t read_eoie_extension(const char *mmap, size_t mmap_size)
3373{
3374        /*
3375         * The end of index entries (EOIE) extension is guaranteed to be last
3376         * so that it can be found by scanning backwards from the EOF.
3377         *
3378         * "EOIE"
3379         * <4-byte length>
3380         * <4-byte offset>
3381         * <20-byte hash>
3382         */
3383        const char *index, *eoie;
3384        uint32_t extsize;
3385        size_t offset, src_offset;
3386        unsigned char hash[GIT_MAX_RAWSZ];
3387        git_hash_ctx c;
3388
3389        /* ensure we have an index big enough to contain an EOIE extension */
3390        if (mmap_size < sizeof(struct cache_header) + EOIE_SIZE_WITH_HEADER + the_hash_algo->rawsz)
3391                return 0;
3392
3393        /* validate the extension signature */
3394        index = eoie = mmap + mmap_size - EOIE_SIZE_WITH_HEADER - the_hash_algo->rawsz;
3395        if (CACHE_EXT(index) != CACHE_EXT_ENDOFINDEXENTRIES)
3396                return 0;
3397        index += sizeof(uint32_t);
3398
3399        /* validate the extension size */
3400        extsize = get_be32(index);
3401        if (extsize != EOIE_SIZE)
3402                return 0;
3403        index += sizeof(uint32_t);
3404
3405        /*
3406         * Validate the offset we're going to look for the first extension
3407         * signature is after the index header and before the eoie extension.
3408         */
3409        offset = get_be32(index);
3410        if (mmap + offset < mmap + sizeof(struct cache_header))
3411                return 0;
3412        if (mmap + offset >= eoie)
3413                return 0;
3414        index += sizeof(uint32_t);
3415
3416        /*
3417         * The hash is computed over extension types and their sizes (but not
3418         * their contents).  E.g. if we have "TREE" extension that is N-bytes
3419         * long, "REUC" extension that is M-bytes long, followed by "EOIE",
3420         * then the hash would be:
3421         *
3422         * SHA-1("TREE" + <binary representation of N> +
3423         *       "REUC" + <binary representation of M>)
3424         */
3425        src_offset = offset;
3426        the_hash_algo->init_fn(&c);
3427        while (src_offset < mmap_size - the_hash_algo->rawsz - EOIE_SIZE_WITH_HEADER) {
3428                /* After an array of active_nr index entries,
3429                 * there can be arbitrary number of extended
3430                 * sections, each of which is prefixed with
3431                 * extension name (4-byte) and section length
3432                 * in 4-byte network byte order.
3433                 */
3434                uint32_t extsize;
3435                memcpy(&extsize, mmap + src_offset + 4, 4);
3436                extsize = ntohl(extsize);
3437
3438                /* verify the extension size isn't so large it will wrap around */
3439                if (src_offset + 8 + extsize < src_offset)
3440                        return 0;
3441
3442                the_hash_algo->update_fn(&c, mmap + src_offset, 8);
3443
3444                src_offset += 8;
3445                src_offset += extsize;
3446        }
3447        the_hash_algo->final_fn(hash, &c);
3448        if (!hasheq(hash, (const unsigned char *)index))
3449                return 0;
3450
3451        /* Validate that the extension offsets returned us back to the eoie extension. */
3452        if (src_offset != mmap_size - the_hash_algo->rawsz - EOIE_SIZE_WITH_HEADER)
3453                return 0;
3454
3455        return offset;
3456}
3457
3458static void write_eoie_extension(struct strbuf *sb, git_hash_ctx *eoie_context, size_t offset)
3459{
3460        uint32_t buffer;
3461        unsigned char hash[GIT_MAX_RAWSZ];
3462
3463        /* offset */
3464        put_be32(&buffer, offset);
3465        strbuf_add(sb, &buffer, sizeof(uint32_t));
3466
3467        /* hash */
3468        the_hash_algo->final_fn(hash, eoie_context);
3469        strbuf_add(sb, hash, the_hash_algo->rawsz);
3470}
3471
3472#ifndef NO_PTHREADS
3473#define IEOT_VERSION    (1)
3474
3475static struct index_entry_offset_table *read_ieot_extension(const char *mmap, size_t mmap_size, size_t offset)
3476{
3477       const char *index = NULL;
3478       uint32_t extsize, ext_version;
3479       struct index_entry_offset_table *ieot;
3480       int i, nr;
3481
3482       /* find the IEOT extension */
3483       if (!offset)
3484               return NULL;
3485       while (offset <= mmap_size - the_hash_algo->rawsz - 8) {
3486               extsize = get_be32(mmap + offset + 4);
3487               if (CACHE_EXT((mmap + offset)) == CACHE_EXT_INDEXENTRYOFFSETTABLE) {
3488                       index = mmap + offset + 4 + 4;
3489                       break;
3490               }
3491               offset += 8;
3492               offset += extsize;
3493       }
3494       if (!index)
3495               return NULL;
3496
3497       /* validate the version is IEOT_VERSION */
3498       ext_version = get_be32(index);
3499       if (ext_version != IEOT_VERSION) {
3500               error("invalid IEOT version %d", ext_version);
3501               return NULL;
3502       }
3503       index += sizeof(uint32_t);
3504
3505       /* extension size - version bytes / bytes per entry */
3506       nr = (extsize - sizeof(uint32_t)) / (sizeof(uint32_t) + sizeof(uint32_t));
3507       if (!nr) {
3508               error("invalid number of IEOT entries %d", nr);
3509               return NULL;
3510       }
3511       ieot = xmalloc(sizeof(struct index_entry_offset_table)
3512               + (nr * sizeof(struct index_entry_offset)));
3513       ieot->nr = nr;
3514       for (i = 0; i < nr; i++) {
3515               ieot->entries[i].offset = get_be32(index);
3516               index += sizeof(uint32_t);
3517               ieot->entries[i].nr = get_be32(index);
3518               index += sizeof(uint32_t);
3519       }
3520
3521       return ieot;
3522}
3523
3524static void write_ieot_extension(struct strbuf *sb, struct index_entry_offset_table *ieot)
3525{
3526       uint32_t buffer;
3527       int i;
3528
3529       /* version */
3530       put_be32(&buffer, IEOT_VERSION);
3531       strbuf_add(sb, &buffer, sizeof(uint32_t));
3532
3533       /* ieot */
3534       for (i = 0; i < ieot->nr; i++) {
3535
3536               /* offset */
3537               put_be32(&buffer, ieot->entries[i].offset);
3538               strbuf_add(sb, &buffer, sizeof(uint32_t));
3539
3540               /* count */
3541               put_be32(&buffer, ieot->entries[i].nr);
3542               strbuf_add(sb, &buffer, sizeof(uint32_t));
3543       }
3544}
3545#endif