diff options
Diffstat (limited to 'read-cache.c')
| -rw-r--r-- | read-cache.c | 1125 |
1 files changed, 1125 insertions, 0 deletions
diff --git a/read-cache.c b/read-cache.c new file mode 100644 index 0000000000..a363f312c7 --- /dev/null +++ b/read-cache.c @@ -0,0 +1,1125 @@ +/* + * GIT - The information manager from hell + * + * Copyright (C) Linus Torvalds, 2005 + */ +#define NO_THE_INDEX_COMPATIBILITY_MACROS +#include "cache.h" +#include "cache-tree.h" +#include "refs.h" + +/* Index extensions. + * + * The first letter should be 'A'..'Z' for extensions that are not + * necessary for a correct operation (i.e. optimization data). + * When new extensions are added that _needs_ to be understood in + * order to correctly interpret the index file, pick character that + * is outside the range, to cause the reader to abort. + */ + +#define CACHE_EXT(s) ( (s[0]<<24)|(s[1]<<16)|(s[2]<<8)|(s[3]) ) +#define CACHE_EXT_TREE 0x54524545 /* "TREE" */ + +struct index_state the_index; + +/* + * This only updates the "non-critical" parts of the directory + * cache, ie the parts that aren't tracked by GIT, and only used + * to validate the cache. + */ +void fill_stat_cache_info(struct cache_entry *ce, struct stat *st) +{ + ce->ce_ctime.sec = htonl(st->st_ctime); + ce->ce_mtime.sec = htonl(st->st_mtime); +#ifdef USE_NSEC + ce->ce_ctime.nsec = htonl(st->st_ctim.tv_nsec); + ce->ce_mtime.nsec = htonl(st->st_mtim.tv_nsec); +#endif + ce->ce_dev = htonl(st->st_dev); + ce->ce_ino = htonl(st->st_ino); + ce->ce_uid = htonl(st->st_uid); + ce->ce_gid = htonl(st->st_gid); + ce->ce_size = htonl(st->st_size); + + if (assume_unchanged) + ce->ce_flags |= htons(CE_VALID); +} + +static int ce_compare_data(struct cache_entry *ce, struct stat *st) +{ + int match = -1; + int fd = open(ce->name, O_RDONLY); + + if (fd >= 0) { + unsigned char sha1[20]; + if (!index_fd(sha1, fd, st, 0, OBJ_BLOB, ce->name)) + match = hashcmp(sha1, ce->sha1); + /* index_fd() closed the file descriptor already */ + } + return match; +} + +static int ce_compare_link(struct cache_entry *ce, size_t expected_size) +{ + int match = -1; + char *target; + void *buffer; + unsigned long size; + enum object_type type; + int len; + + target = xmalloc(expected_size); + len = readlink(ce->name, target, expected_size); + if (len != expected_size) { + free(target); + return -1; + } + buffer = read_sha1_file(ce->sha1, &type, &size); + if (!buffer) { + free(target); + return -1; + } + if (size == expected_size) + match = memcmp(buffer, target, size); + free(buffer); + free(target); + return match; +} + +static int ce_compare_gitlink(struct cache_entry *ce) +{ + unsigned char sha1[20]; + + /* + * We don't actually require that the .git directory + * under GITLINK directory be a valid git directory. It + * might even be missing (in case nobody populated that + * sub-project). + * + * If so, we consider it always to match. + */ + if (resolve_gitlink_ref(ce->name, "HEAD", sha1) < 0) + return 0; + return hashcmp(sha1, ce->sha1); +} + +static int ce_modified_check_fs(struct cache_entry *ce, struct stat *st) +{ + switch (st->st_mode & S_IFMT) { + case S_IFREG: + if (ce_compare_data(ce, st)) + return DATA_CHANGED; + break; + case S_IFLNK: + if (ce_compare_link(ce, xsize_t(st->st_size))) + return DATA_CHANGED; + break; + case S_IFDIR: + if (S_ISGITLINK(ntohl(ce->ce_mode))) + return 0; + default: + return TYPE_CHANGED; + } + return 0; +} + +static int ce_match_stat_basic(struct cache_entry *ce, struct stat *st) +{ + unsigned int changed = 0; + + switch (ntohl(ce->ce_mode) & S_IFMT) { + case S_IFREG: + changed |= !S_ISREG(st->st_mode) ? TYPE_CHANGED : 0; + /* We consider only the owner x bit to be relevant for + * "mode changes" + */ + if (trust_executable_bit && + (0100 & (ntohl(ce->ce_mode) ^ st->st_mode))) + changed |= MODE_CHANGED; + break; + case S_IFLNK: + if (!S_ISLNK(st->st_mode) && + (has_symlinks || !S_ISREG(st->st_mode))) + changed |= TYPE_CHANGED; + break; + case S_IFGITLINK: + if (!S_ISDIR(st->st_mode)) + changed |= TYPE_CHANGED; + else if (ce_compare_gitlink(ce)) + changed |= DATA_CHANGED; + return changed; + default: + die("internal error: ce_mode is %o", ntohl(ce->ce_mode)); + } + if (ce->ce_mtime.sec != htonl(st->st_mtime)) + changed |= MTIME_CHANGED; + if (ce->ce_ctime.sec != htonl(st->st_ctime)) + changed |= CTIME_CHANGED; + +#ifdef USE_NSEC + /* + * nsec seems unreliable - not all filesystems support it, so + * as long as it is in the inode cache you get right nsec + * but after it gets flushed, you get zero nsec. + */ + if (ce->ce_mtime.nsec != htonl(st->st_mtim.tv_nsec)) + changed |= MTIME_CHANGED; + if (ce->ce_ctime.nsec != htonl(st->st_ctim.tv_nsec)) + changed |= CTIME_CHANGED; +#endif + + if (ce->ce_uid != htonl(st->st_uid) || + ce->ce_gid != htonl(st->st_gid)) + changed |= OWNER_CHANGED; + if (ce->ce_ino != htonl(st->st_ino)) + changed |= INODE_CHANGED; + +#ifdef USE_STDEV + /* + * st_dev breaks on network filesystems where different + * clients will have different views of what "device" + * the filesystem is on + */ + if (ce->ce_dev != htonl(st->st_dev)) + changed |= INODE_CHANGED; +#endif + + if (ce->ce_size != htonl(st->st_size)) + changed |= DATA_CHANGED; + + return changed; +} + +int ie_match_stat(struct index_state *istate, + struct cache_entry *ce, struct stat *st, int options) +{ + unsigned int changed; + int ignore_valid = options & 01; + int assume_racy_is_modified = options & 02; + + /* + * If it's marked as always valid in the index, it's + * valid whatever the checked-out copy says. + */ + if (!ignore_valid && (ce->ce_flags & htons(CE_VALID))) + return 0; + + changed = ce_match_stat_basic(ce, st); + + /* + * Within 1 second of this sequence: + * echo xyzzy >file && git-update-index --add file + * running this command: + * echo frotz >file + * would give a falsely clean cache entry. The mtime and + * length match the cache, and other stat fields do not change. + * + * We could detect this at update-index time (the cache entry + * being registered/updated records the same time as "now") + * and delay the return from git-update-index, but that would + * effectively mean we can make at most one commit per second, + * which is not acceptable. Instead, we check cache entries + * whose mtime are the same as the index file timestamp more + * carefully than others. + */ + if (!changed && + istate->timestamp && + istate->timestamp <= ntohl(ce->ce_mtime.sec)) { + if (assume_racy_is_modified) + changed |= DATA_CHANGED; + else + changed |= ce_modified_check_fs(ce, st); + } + + return changed; +} + +int ie_modified(struct index_state *istate, + struct cache_entry *ce, struct stat *st, int really) +{ + int changed, changed_fs; + changed = ie_match_stat(istate, ce, st, really); + if (!changed) + return 0; + /* + * If the mode or type has changed, there's no point in trying + * to refresh the entry - it's not going to match + */ + if (changed & (MODE_CHANGED | TYPE_CHANGED)) + return changed; + + /* Immediately after read-tree or update-index --cacheinfo, + * the length field is zero. For other cases the ce_size + * should match the SHA1 recorded in the index entry. + */ + if ((changed & DATA_CHANGED) && ce->ce_size != htonl(0)) + return changed; + + changed_fs = ce_modified_check_fs(ce, st); + if (changed_fs) + return changed | changed_fs; + return 0; +} + +int base_name_compare(const char *name1, int len1, int mode1, + const char *name2, int len2, int mode2) +{ + unsigned char c1, c2; + int len = len1 < len2 ? len1 : len2; + int cmp; + + cmp = memcmp(name1, name2, len); + if (cmp) + return cmp; + c1 = name1[len]; + c2 = name2[len]; + if (!c1 && S_ISDIR(mode1)) + c1 = '/'; + if (!c2 && S_ISDIR(mode2)) + c2 = '/'; + return (c1 < c2) ? -1 : (c1 > c2) ? 1 : 0; +} + +int cache_name_compare(const char *name1, int flags1, const char *name2, int flags2) +{ + int len1 = flags1 & CE_NAMEMASK; + int len2 = flags2 & CE_NAMEMASK; + int len = len1 < len2 ? len1 : len2; + int cmp; + + cmp = memcmp(name1, name2, len); + if (cmp) + return cmp; + if (len1 < len2) + return -1; + if (len1 > len2) + return 1; + + /* Compare stages */ + flags1 &= CE_STAGEMASK; + flags2 &= CE_STAGEMASK; + + if (flags1 < flags2) + return -1; + if (flags1 > flags2) + return 1; + return 0; +} + +int index_name_pos(struct index_state *istate, const char *name, int namelen) +{ + int first, last; + + first = 0; + last = istate->cache_nr; + while (last > first) { + int next = (last + first) >> 1; + struct cache_entry *ce = istate->cache[next]; + int cmp = cache_name_compare(name, namelen, ce->name, ntohs(ce->ce_flags)); + if (!cmp) + return next; + if (cmp < 0) { + last = next; + continue; + } + first = next+1; + } + return -first-1; +} + +/* Remove entry, return true if there are more entries to go.. */ +int remove_index_entry_at(struct index_state *istate, int pos) +{ + istate->cache_changed = 1; + istate->cache_nr--; + if (pos >= istate->cache_nr) + return 0; + memmove(istate->cache + pos, + istate->cache + pos + 1, + (istate->cache_nr - pos) * sizeof(struct cache_entry *)); + return 1; +} + +int remove_file_from_index(struct index_state *istate, const char *path) +{ + int pos = index_name_pos(istate, path, strlen(path)); + if (pos < 0) + pos = -pos-1; + while (pos < istate->cache_nr && !strcmp(istate->cache[pos]->name, path)) + remove_index_entry_at(istate, pos); + return 0; +} + +static int compare_name(struct cache_entry *ce, const char *path, int namelen) +{ + return namelen != ce_namelen(ce) || memcmp(path, ce->name, namelen); +} + +static int index_name_pos_also_unmerged(struct index_state *istate, + const char *path, int namelen) +{ + int pos = index_name_pos(istate, path, namelen); + struct cache_entry *ce; + + if (pos >= 0) + return pos; + + /* maybe unmerged? */ + pos = -1 - pos; + if (pos >= istate->cache_nr || + compare_name((ce = istate->cache[pos]), path, namelen)) + return -1; + + /* order of preference: stage 2, 1, 3 */ + if (ce_stage(ce) == 1 && pos + 1 < istate->cache_nr && + ce_stage((ce = istate->cache[pos + 1])) == 2 && + !compare_name(ce, path, namelen)) + pos++; + return pos; +} + +int add_file_to_index(struct index_state *istate, const char *path, int verbose) +{ + int size, namelen; + struct stat st; + struct cache_entry *ce; + + if (lstat(path, &st)) + die("%s: unable to stat (%s)", path, strerror(errno)); + + if (!S_ISREG(st.st_mode) && !S_ISLNK(st.st_mode) && !S_ISDIR(st.st_mode)) + die("%s: can only add regular files, symbolic links or git-directories", path); + + namelen = strlen(path); + if (S_ISDIR(st.st_mode)) { + while (namelen && path[namelen-1] == '/') + namelen--; + } + size = cache_entry_size(namelen); + ce = xcalloc(1, size); + memcpy(ce->name, path, namelen); + ce->ce_flags = htons(namelen); + fill_stat_cache_info(ce, &st); + + if (trust_executable_bit && has_symlinks) + ce->ce_mode = create_ce_mode(st.st_mode); + else { + /* If there is an existing entry, pick the mode bits and type + * from it, otherwise assume unexecutable regular file. + */ + struct cache_entry *ent; + int pos = index_name_pos_also_unmerged(istate, path, namelen); + + ent = (0 <= pos) ? istate->cache[pos] : NULL; + ce->ce_mode = ce_mode_from_stat(ent, st.st_mode); + } + + if (index_path(ce->sha1, path, &st, 1)) + die("unable to index file %s", path); + if (add_index_entry(istate, ce, ADD_CACHE_OK_TO_ADD|ADD_CACHE_OK_TO_REPLACE)) + die("unable to add %s to index",path); + if (verbose) + printf("add '%s'\n", path); + cache_tree_invalidate_path(istate->cache_tree, path); + return 0; +} + +int ce_same_name(struct cache_entry *a, struct cache_entry *b) +{ + int len = ce_namelen(a); + return ce_namelen(b) == len && !memcmp(a->name, b->name, len); +} + +int ce_path_match(const struct cache_entry *ce, const char **pathspec) +{ + const char *match, *name; + int len; + + if (!pathspec) + return 1; + + len = ce_namelen(ce); + name = ce->name; + while ((match = *pathspec++) != NULL) { + int matchlen = strlen(match); + if (matchlen > len) + continue; + if (memcmp(name, match, matchlen)) + continue; + if (matchlen && name[matchlen-1] == '/') + return 1; + if (name[matchlen] == '/' || !name[matchlen]) + return 1; + if (!matchlen) + return 1; + } + return 0; +} + +/* + * We fundamentally don't like some paths: we don't want + * dot or dot-dot anywhere, and for obvious reasons don't + * want to recurse into ".git" either. + * + * Also, we don't want double slashes or slashes at the + * end that can make pathnames ambiguous. + */ +static int verify_dotfile(const char *rest) +{ + /* + * The first character was '.', but that + * has already been discarded, we now test + * the rest. + */ + switch (*rest) { + /* "." is not allowed */ + case '\0': case '/': + return 0; + + /* + * ".git" followed by NUL or slash is bad. This + * shares the path end test with the ".." case. + */ + case 'g': + if (rest[1] != 'i') + break; + if (rest[2] != 't') + break; + rest += 2; + /* fallthrough */ + case '.': + if (rest[1] == '\0' || rest[1] == '/') + return 0; + } + return 1; +} + +int verify_path(const char *path) +{ + char c; + + goto inside; + for (;;) { + if (!c) + return 1; + if (c == '/') { +inside: + c = *path++; + switch (c) { + default: + continue; + case '/': case '\0': + break; + case '.': + if (verify_dotfile(path)) + continue; + } + return 0; + } + c = *path++; + } +} + +/* + * Do we have another file that has the beginning components being a + * proper superset of the name we're trying to add? + */ +static int has_file_name(struct index_state *istate, + const struct cache_entry *ce, int pos, int ok_to_replace) +{ + int retval = 0; + int len = ce_namelen(ce); + int stage = ce_stage(ce); + const char *name = ce->name; + + while (pos < istate->cache_nr) { + struct cache_entry *p = istate->cache[pos++]; + + if (len >= ce_namelen(p)) + break; + if (memcmp(name, p->name, len)) + break; + if (ce_stage(p) != stage) + continue; + if (p->name[len] != '/') + continue; + if (!ce_stage(p) && !p->ce_mode) + continue; + retval = -1; + if (!ok_to_replace) + break; + remove_index_entry_at(istate, --pos); + } + return retval; +} + +/* + * Do we have another file with a pathname that is a proper + * subset of the name we're trying to add? + */ +static int has_dir_name(struct index_state *istate, + const struct cache_entry *ce, int pos, int ok_to_replace) +{ + int retval = 0; + int stage = ce_stage(ce); + const char *name = ce->name; + const char *slash = name + ce_namelen(ce); + + for (;;) { + int len; + + for (;;) { + if (*--slash == '/') + break; + if (slash <= ce->name) + return retval; + } + len = slash - name; + + pos = index_name_pos(istate, name, ntohs(create_ce_flags(len, stage))); + if (pos >= 0) { + /* + * Found one, but not so fast. This could + * be a marker that says "I was here, but + * I am being removed". Such an entry is + * not a part of the resulting tree, and + * it is Ok to have a directory at the same + * path. + */ + if (stage || istate->cache[pos]->ce_mode) { + retval = -1; + if (!ok_to_replace) + break; + remove_index_entry_at(istate, pos); + continue; + } + } + else + pos = -pos-1; + + /* + * Trivial optimization: if we find an entry that + * already matches the sub-directory, then we know + * we're ok, and we can exit. + */ + while (pos < istate->cache_nr) { + struct cache_entry *p = istate->cache[pos]; + if ((ce_namelen(p) <= len) || + (p->name[len] != '/') || + memcmp(p->name, name, len)) + break; /* not our subdirectory */ + if (ce_stage(p) == stage && (stage || p->ce_mode)) + /* p is at the same stage as our entry, and + * is a subdirectory of what we are looking + * at, so we cannot have conflicts at our + * level or anything shorter. + */ + return retval; + pos++; + } + } + return retval; +} + +/* We may be in a situation where we already have path/file and path + * is being added, or we already have path and path/file is being + * added. Either one would result in a nonsense tree that has path + * twice when git-write-tree tries to write it out. Prevent it. + * + * If ok-to-replace is specified, we remove the conflicting entries + * from the cache so the caller should recompute the insert position. + * When this happens, we return non-zero. + */ +static int check_file_directory_conflict(struct index_state *istate, + const struct cache_entry *ce, + int pos, int ok_to_replace) +{ + int retval; + + /* + * When ce is an "I am going away" entry, we allow it to be added + */ + if (!ce_stage(ce) && !ce->ce_mode) + return 0; + + /* + * We check if the path is a sub-path of a subsequent pathname + * first, since removing those will not change the position + * in the array. + */ + retval = has_file_name(istate, ce, pos, ok_to_replace); + + /* + * Then check if the path might have a clashing sub-directory + * before it. + */ + return retval + has_dir_name(istate, ce, pos, ok_to_replace); +} + +int add_index_entry(struct index_state *istate, struct cache_entry *ce, int option) +{ + int pos; + int ok_to_add = option & ADD_CACHE_OK_TO_ADD; + int ok_to_replace = option & ADD_CACHE_OK_TO_REPLACE; + int skip_df_check = option & ADD_CACHE_SKIP_DFCHECK; + + pos = index_name_pos(istate, ce->name, ntohs(ce->ce_flags)); + + /* existing match? Just replace it. */ + if (pos >= 0) { + istate->cache_changed = 1; + istate->cache[pos] = ce; + return 0; + } + pos = -pos-1; + + /* + * Inserting a merged entry ("stage 0") into the index + * will always replace all non-merged entries.. + */ + if (pos < istate->cache_nr && ce_stage(ce) == 0) { + while (ce_same_name(istate->cache[pos], ce)) { + ok_to_add = 1; + if (!remove_index_entry_at(istate, pos)) + break; + } + } + + if (!ok_to_add) + return -1; + if (!verify_path(ce->name)) + return -1; + + if (!skip_df_check && + check_file_directory_conflict(istate, ce, pos, ok_to_replace)) { + if (!ok_to_replace) + return error("'%s' appears as both a file and as a directory", + ce->name); + pos = index_name_pos(istate, ce->name, ntohs(ce->ce_flags)); + pos = -pos-1; + } + + /* Make sure the array is big enough .. */ + if (istate->cache_nr == istate->cache_alloc) { + istate->cache_alloc = alloc_nr(istate->cache_alloc); + istate->cache = xrealloc(istate->cache, + istate->cache_alloc * sizeof(struct cache_entry *)); + } + + /* Add it in.. */ + istate->cache_nr++; + if (istate->cache_nr > pos) + memmove(istate->cache + pos + 1, + istate->cache + pos, + (istate->cache_nr - pos - 1) * sizeof(ce)); + istate->cache[pos] = ce; + istate->cache_changed = 1; + return 0; +} + +/* + * "refresh" does not calculate a new sha1 file or bring the + * cache up-to-date for mode/content changes. But what it + * _does_ do is to "re-match" the stat information of a file + * with the cache, so that you can refresh the cache for a + * file that hasn't been changed but where the stat entry is + * out of date. + * + * For example, you'd want to do this after doing a "git-read-tree", + * to link up the stat cache details with the proper files. + */ +static struct cache_entry *refresh_cache_ent(struct index_state *istate, + struct cache_entry *ce, int really, int *err) +{ + struct stat st; + struct cache_entry *updated; + int changed, size; + + if (lstat(ce->name, &st) < 0) { + if (err) + *err = errno; + return NULL; + } + + changed = ie_match_stat(istate, ce, &st, really); + if (!changed) { + if (really && assume_unchanged && + !(ce->ce_flags & htons(CE_VALID))) + ; /* mark this one VALID again */ + else + return ce; + } + + if (ie_modified(istate, ce, &st, really)) { + if (err) + *err = EINVAL; + return NULL; + } + + size = ce_size(ce); + updated = xmalloc(size); + memcpy(updated, ce, size); + fill_stat_cache_info(updated, &st); + + /* In this case, if really is not set, we should leave + * CE_VALID bit alone. Otherwise, paths marked with + * --no-assume-unchanged (i.e. things to be edited) will + * reacquire CE_VALID bit automatically, which is not + * really what we want. + */ + if (!really && assume_unchanged && !(ce->ce_flags & htons(CE_VALID))) + updated->ce_flags &= ~htons(CE_VALID); + + return updated; +} + +int refresh_index(struct index_state *istate, unsigned int flags) +{ + int i; + int has_errors = 0; + int really = (flags & REFRESH_REALLY) != 0; + int allow_unmerged = (flags & REFRESH_UNMERGED) != 0; + int quiet = (flags & REFRESH_QUIET) != 0; + int not_new = (flags & REFRESH_IGNORE_MISSING) != 0; + + for (i = 0; i < istate->cache_nr; i++) { + struct cache_entry *ce, *new; + int cache_errno = 0; + + ce = istate->cache[i]; + if (ce_stage(ce)) { + while ((i < istate->cache_nr) && + ! strcmp(istate->cache[i]->name, ce->name)) + i++; + i--; + if (allow_unmerged) + continue; + printf("%s: needs merge\n", ce->name); + has_errors = 1; + continue; + } + + new = refresh_cache_ent(istate, ce, really, &cache_errno); + if (new == ce) + continue; + if (!new) { + if (not_new && cache_errno == ENOENT) + continue; + if (really && cache_errno == EINVAL) { + /* If we are doing --really-refresh that + * means the index is not valid anymore. + */ + ce->ce_flags &= ~htons(CE_VALID); + istate->cache_changed = 1; + } + if (quiet) + continue; + printf("%s: needs update\n", ce->name); + has_errors = 1; + continue; + } + istate->cache_changed = 1; + /* You can NOT just free istate->cache[i] here, since it + * might not be necessarily malloc()ed but can also come + * from mmap(). */ + istate->cache[i] = new; + } + return has_errors; +} + +struct cache_entry *refresh_cache_entry(struct cache_entry *ce, int really) +{ + return refresh_cache_ent(&the_index, ce, really, NULL); +} + +static int verify_hdr(struct cache_header *hdr, unsigned long size) +{ + SHA_CTX c; + unsigned char sha1[20]; + + if (hdr->hdr_signature != htonl(CACHE_SIGNATURE)) + return error("bad signature"); + if (hdr->hdr_version != htonl(2)) + return error("bad index version"); + SHA1_Init(&c); + SHA1_Update(&c, hdr, size - 20); + SHA1_Final(sha1, &c); + if (hashcmp(sha1, (unsigned char *)hdr + size - 20)) + return error("bad index file sha1 signature"); + return 0; +} + +static int read_index_extension(struct index_state *istate, + const char *ext, void *data, unsigned long sz) +{ + switch (CACHE_EXT(ext)) { + case CACHE_EXT_TREE: + istate->cache_tree = cache_tree_read(data, sz); + break; + default: + if (*ext < 'A' || 'Z' < *ext) + return error("index uses %.4s extension, which we do not understand", + ext); + fprintf(stderr, "ignoring %.4s extension\n", ext); + break; + } + return 0; +} + +int read_index(struct index_state *istate) +{ + return read_index_from(istate, get_index_file()); +} + +/* remember to discard_cache() before reading a different cache! */ +int read_index_from(struct index_state *istate, const char *path) +{ + int fd, i; + struct stat st; + unsigned long offset; + struct cache_header *hdr; + + errno = EBUSY; + if (istate->mmap) + return istate->cache_nr; + + errno = ENOENT; + istate->timestamp = 0; + fd = open(path, O_RDONLY); + if (fd < 0) { + if (errno == ENOENT) + return 0; + die("index file open failed (%s)", strerror(errno)); + } + + if (fstat(fd, &st)) + die("cannot stat the open index (%s)", strerror(errno)); + + errno = EINVAL; + istate->mmap_size = xsize_t(st.st_size); + if (istate->mmap_size < sizeof(struct cache_header) + 20) + die("index file smaller than expected"); + + istate->mmap = xmmap(NULL, istate->mmap_size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0); + close(fd); + + hdr = istate->mmap; + if (verify_hdr(hdr, istate->mmap_size) < 0) + goto unmap; + + istate->cache_nr = ntohl(hdr->hdr_entries); + istate->cache_alloc = alloc_nr(istate->cache_nr); + istate->cache = xcalloc(istate->cache_alloc, sizeof(struct cache_entry *)); + + offset = sizeof(*hdr); + for (i = 0; i < istate->cache_nr; i++) { + struct cache_entry *ce; + + ce = (struct cache_entry *)((char *)(istate->mmap) + offset); + offset = offset + ce_size(ce); + istate->cache[i] = ce; + } + istate->timestamp = st.st_mtime; + while (offset <= istate->mmap_size - 20 - 8) { + /* After an array of active_nr index entries, + * there can be arbitrary number of extended + * sections, each of which is prefixed with + * extension name (4-byte) and section length + * in 4-byte network byte order. + */ + unsigned long extsize; + memcpy(&extsize, (char *)(istate->mmap) + offset + 4, 4); + extsize = ntohl(extsize); + if (read_index_extension(istate, + ((const char *) (istate->mmap)) + offset, + (char *) (istate->mmap) + offset + 8, + extsize) < 0) + goto unmap; + offset += 8; + offset += extsize; + } + return istate->cache_nr; + +unmap: + munmap(istate->mmap, istate->mmap_size); + errno = EINVAL; + die("index file corrupt"); +} + +int discard_index(struct index_state *istate) +{ + int ret; + + istate->cache_nr = 0; + istate->cache_changed = 0; + istate->timestamp = 0; + cache_tree_free(&(istate->cache_tree)); + if (istate->mmap == NULL) + return 0; + ret = munmap(istate->mmap, istate->mmap_size); + istate->mmap = NULL; + istate->mmap_size = 0; + + /* no need to throw away allocated active_cache */ + return ret; +} + +#define WRITE_BUFFER_SIZE 8192 +static unsigned char write_buffer[WRITE_BUFFER_SIZE]; +static unsigned long write_buffer_len; + +static int ce_write_flush(SHA_CTX *context, int fd) +{ + unsigned int buffered = write_buffer_len; + if (buffered) { + SHA1_Update(context, write_buffer, buffered); + if (write_in_full(fd, write_buffer, buffered) != buffered) + return -1; + write_buffer_len = 0; + } + return 0; +} + +static int ce_write(SHA_CTX *context, int fd, void *data, unsigned int len) +{ + while (len) { + unsigned int buffered = write_buffer_len; + unsigned int partial = WRITE_BUFFER_SIZE - buffered; + if (partial > len) + partial = len; + memcpy(write_buffer + buffered, data, partial); + buffered += partial; + if (buffered == WRITE_BUFFER_SIZE) { + write_buffer_len = buffered; + if (ce_write_flush(context, fd)) + return -1; + buffered = 0; + } + write_buffer_len = buffered; + len -= partial; + data = (char *) data + partial; + } + return 0; +} + +static int write_index_ext_header(SHA_CTX *context, int fd, + unsigned int ext, unsigned int sz) +{ + ext = htonl(ext); + sz = htonl(sz); + return ((ce_write(context, fd, &ext, 4) < 0) || + (ce_write(context, fd, &sz, 4) < 0)) ? -1 : 0; +} + +static int ce_flush(SHA_CTX *context, int fd) +{ + unsigned int left = write_buffer_len; + + if (left) { + write_buffer_len = 0; + SHA1_Update(context, write_buffer, left); + } + + /* Flush first if not enough space for SHA1 signature */ + if (left + 20 > WRITE_BUFFER_SIZE) { + if (write_in_full(fd, write_buffer, left) != left) + return -1; + left = 0; + } + + /* Append the SHA1 signature at the end */ + SHA1_Final(write_buffer + left, context); + left += 20; + return (write_in_full(fd, write_buffer, left) != left) ? -1 : 0; +} + +static void ce_smudge_racily_clean_entry(struct cache_entry *ce) +{ + /* + * The only thing we care about in this function is to smudge the + * falsely clean entry due to touch-update-touch race, so we leave + * everything else as they are. We are called for entries whose + * ce_mtime match the index file mtime. + */ + struct stat st; + + if (lstat(ce->name, &st) < 0) + return; + if (ce_match_stat_basic(ce, &st)) + return; + if (ce_modified_check_fs(ce, &st)) { + /* This is "racily clean"; smudge it. Note that this + * is a tricky code. At first glance, it may appear + * that it can break with this sequence: + * + * $ echo xyzzy >frotz + * $ git-update-index --add frotz + * $ : >frotz + * $ sleep 3 + * $ echo filfre >nitfol + * $ git-update-index --add nitfol + * + * but it does not. When the second update-index runs, + * it notices that the entry "frotz" has the same timestamp + * as index, and if we were to smudge it by resetting its + * size to zero here, then the object name recorded + * in index is the 6-byte file but the cached stat information + * becomes zero --- which would then match what we would + * obtain from the filesystem next time we stat("frotz"). + * + * However, the second update-index, before calling + * this function, notices that the cached size is 6 + * bytes and what is on the filesystem is an empty + * file, and never calls us, so the cached size information + * for "frotz" stays 6 which does not match the filesystem. + */ + ce->ce_size = htonl(0); + } +} + +int write_index(struct index_state *istate, int newfd) +{ + SHA_CTX c; + struct cache_header hdr; + int i, removed; + struct cache_entry **cache = istate->cache; + int entries = istate->cache_nr; + + for (i = removed = 0; i < entries; i++) + if (!cache[i]->ce_mode) + removed++; + + hdr.hdr_signature = htonl(CACHE_SIGNATURE); + hdr.hdr_version = htonl(2); + hdr.hdr_entries = htonl(entries - removed); + + SHA1_Init(&c); + if (ce_write(&c, newfd, &hdr, sizeof(hdr)) < 0) + return -1; + + for (i = 0; i < entries; i++) { + struct cache_entry *ce = cache[i]; + if (!ce->ce_mode) + continue; + if (istate->timestamp && + istate->timestamp <= ntohl(ce->ce_mtime.sec)) + ce_smudge_racily_clean_entry(ce); + if (ce_write(&c, newfd, ce, ce_size(ce)) < 0) + return -1; + } + + /* Write extension data here */ + if (istate->cache_tree) { + unsigned long sz; + void *data = cache_tree_write(istate->cache_tree, &sz); + if (data && + !write_index_ext_header(&c, newfd, CACHE_EXT_TREE, sz) && + !ce_write(&c, newfd, data, sz)) + free(data); + else { + free(data); + return -1; + } + } + return ce_flush(&c, newfd); +} |