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-rw-r--r--read-cache.c1021
1 files changed, 1021 insertions, 0 deletions
diff --git a/read-cache.c b/read-cache.c
new file mode 100644
index 0000000000..605b352396
--- /dev/null
+++ b/read-cache.c
@@ -0,0 +1,1021 @@
+/*
+ * GIT - The information manager from hell
+ *
+ * Copyright (C) Linus Torvalds, 2005
+ */
+#include "cache.h"
+#include "cache-tree.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 cache_entry **active_cache;
+static time_t index_file_timestamp;
+unsigned int active_nr, active_alloc, active_cache_changed;
+
+struct cache_tree *active_cache_tree;
+
+int cache_errno;
+
+static void *cache_mmap;
+static size_t cache_mmap_size;
+
+/*
+ * 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, NULL))
+ match = hashcmp(sha1, ce->sha1);
+ /* index_fd() closed the file descriptor already */
+ }
+ return match;
+}
+
+static int ce_compare_link(struct cache_entry *ce, unsigned long expected_size)
+{
+ int match = -1;
+ char *target;
+ void *buffer;
+ unsigned long size;
+ char type[10];
+ 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_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, st->st_size))
+ return DATA_CHANGED;
+ break;
+ 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:
+ changed |= !S_ISLNK(st->st_mode) ? TYPE_CHANGED : 0;
+ break;
+ 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 ce_match_stat(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 &&
+ index_file_timestamp &&
+ index_file_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 ce_modified(struct cache_entry *ce, struct stat *st, int really)
+{
+ int changed, changed_fs;
+ changed = ce_match_stat(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 cache_name_pos(const char *name, int namelen)
+{
+ int first, last;
+
+ first = 0;
+ last = active_nr;
+ while (last > first) {
+ int next = (last + first) >> 1;
+ struct cache_entry *ce = active_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_cache_entry_at(int pos)
+{
+ active_cache_changed = 1;
+ active_nr--;
+ if (pos >= active_nr)
+ return 0;
+ memmove(active_cache + pos, active_cache + pos + 1, (active_nr - pos) * sizeof(struct cache_entry *));
+ return 1;
+}
+
+int remove_file_from_cache(const char *path)
+{
+ int pos = cache_name_pos(path, strlen(path));
+ if (pos < 0)
+ pos = -pos-1;
+ while (pos < active_nr && !strcmp(active_cache[pos]->name, path))
+ remove_cache_entry_at(pos);
+ return 0;
+}
+
+int add_file_to_index(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))
+ die("%s: can only add regular files or symbolic links", path);
+
+ namelen = strlen(path);
+ 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)
+ ce->ce_mode = create_ce_mode(st.st_mode);
+ else {
+ /* If there is an existing entry, pick the mode bits
+ * from it, otherwise assume unexecutable.
+ */
+ struct cache_entry *ent;
+ int pos = cache_name_pos(path, namelen);
+
+ ent = (0 <= pos) ? active_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_cache_entry(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(active_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(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 < active_nr) {
+ struct cache_entry *p = active_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;
+ retval = -1;
+ if (!ok_to_replace)
+ break;
+ remove_cache_entry_at(--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(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 = cache_name_pos(name, ntohs(create_ce_flags(len, stage)));
+ if (pos >= 0) {
+ retval = -1;
+ if (!ok_to_replace)
+ break;
+ remove_cache_entry_at(pos);
+ continue;
+ }
+
+ /*
+ * Trivial optimization: if we find an entry that
+ * already matches the sub-directory, then we know
+ * we're ok, and we can exit.
+ */
+ pos = -pos-1;
+ while (pos < active_nr) {
+ struct cache_entry *p = active_cache[pos];
+ if ((ce_namelen(p) <= len) ||
+ (p->name[len] != '/') ||
+ memcmp(p->name, name, len))
+ break; /* not our subdirectory */
+ if (ce_stage(p) == stage)
+ /* 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(const struct cache_entry *ce, int pos, int ok_to_replace)
+{
+ /*
+ * 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
+ */
+ int retval = has_file_name(ce, pos, ok_to_replace);
+ /*
+ * Then check if the path might have a clashing sub-directory
+ * before it.
+ */
+ return retval + has_dir_name(ce, pos, ok_to_replace);
+}
+
+int add_cache_entry(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 = cache_name_pos(ce->name, ntohs(ce->ce_flags));
+
+ /* existing match? Just replace it. */
+ if (pos >= 0) {
+ active_cache_changed = 1;
+ active_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 < active_nr && ce_stage(ce) == 0) {
+ while (ce_same_name(active_cache[pos], ce)) {
+ ok_to_add = 1;
+ if (!remove_cache_entry_at(pos))
+ break;
+ }
+ }
+
+ if (!ok_to_add)
+ return -1;
+ if (!verify_path(ce->name))
+ return -1;
+
+ if (!skip_df_check &&
+ check_file_directory_conflict(ce, pos, ok_to_replace)) {
+ if (!ok_to_replace)
+ return error("'%s' appears as both a file and as a directory", ce->name);
+ pos = cache_name_pos(ce->name, ntohs(ce->ce_flags));
+ pos = -pos-1;
+ }
+
+ /* Make sure the array is big enough .. */
+ if (active_nr == active_alloc) {
+ active_alloc = alloc_nr(active_alloc);
+ active_cache = xrealloc(active_cache, active_alloc * sizeof(struct cache_entry *));
+ }
+
+ /* Add it in.. */
+ active_nr++;
+ if (active_nr > pos)
+ memmove(active_cache + pos + 1, active_cache + pos, (active_nr - pos - 1) * sizeof(ce));
+ active_cache[pos] = ce;
+ active_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.
+ */
+struct cache_entry *refresh_cache_entry(struct cache_entry *ce, int really)
+{
+ struct stat st;
+ struct cache_entry *updated;
+ int changed, size;
+
+ if (lstat(ce->name, &st) < 0) {
+ cache_errno = errno;
+ return NULL;
+ }
+
+ changed = ce_match_stat(ce, &st, really);
+ if (!changed) {
+ if (really && assume_unchanged &&
+ !(ce->ce_flags & htons(CE_VALID)))
+ ; /* mark this one VALID again */
+ else
+ return ce;
+ }
+
+ if (ce_modified(ce, &st, really)) {
+ cache_errno = 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_cache(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 < active_nr; i++) {
+ struct cache_entry *ce, *new;
+ ce = active_cache[i];
+ if (ce_stage(ce)) {
+ while ((i < active_nr) &&
+ ! strcmp(active_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_entry(ce, really);
+ 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);
+ active_cache_changed = 1;
+ }
+ if (quiet)
+ continue;
+ printf("%s: needs update\n", ce->name);
+ has_errors = 1;
+ continue;
+ }
+ active_cache_changed = 1;
+ /* You can NOT just free active_cache[i] here, since it
+ * might not be necessarily malloc()ed but can also come
+ * from mmap(). */
+ active_cache[i] = new;
+ }
+ return has_errors;
+}
+
+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(const char *ext, void *data, unsigned long sz)
+{
+ switch (CACHE_EXT(ext)) {
+ case CACHE_EXT_TREE:
+ active_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_cache(void)
+{
+ return read_cache_from(get_index_file());
+}
+
+/* remember to discard_cache() before reading a different cache! */
+int read_cache_from(const char *path)
+{
+ int fd, i;
+ struct stat st;
+ unsigned long offset;
+ struct cache_header *hdr;
+
+ errno = EBUSY;
+ if (cache_mmap)
+ return active_nr;
+
+ errno = ENOENT;
+ index_file_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)) {
+ cache_mmap_size = st.st_size;
+ errno = EINVAL;
+ if (cache_mmap_size >= sizeof(struct cache_header) + 20)
+ cache_mmap = xmmap(NULL, cache_mmap_size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
+ else
+ die("index file smaller than expected");
+ } else
+ die("cannot stat the open index (%s)", strerror(errno));
+ close(fd);
+
+ hdr = cache_mmap;
+ if (verify_hdr(hdr, cache_mmap_size) < 0)
+ goto unmap;
+
+ active_nr = ntohl(hdr->hdr_entries);
+ active_alloc = alloc_nr(active_nr);
+ active_cache = xcalloc(active_alloc, sizeof(struct cache_entry *));
+
+ offset = sizeof(*hdr);
+ for (i = 0; i < active_nr; i++) {
+ struct cache_entry *ce = (struct cache_entry *) ((char *) cache_mmap + offset);
+ offset = offset + ce_size(ce);
+ active_cache[i] = ce;
+ }
+ index_file_timestamp = st.st_mtime;
+ while (offset <= cache_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 *) cache_mmap + offset + 4, 4);
+ extsize = ntohl(extsize);
+ if (read_index_extension(((const char *) cache_mmap) + offset,
+ (char *) cache_mmap + offset + 8,
+ extsize) < 0)
+ goto unmap;
+ offset += 8;
+ offset += extsize;
+ }
+ return active_nr;
+
+unmap:
+ munmap(cache_mmap, cache_mmap_size);
+ errno = EINVAL;
+ die("index file corrupt");
+}
+
+int discard_cache(void)
+{
+ int ret;
+
+ active_nr = active_cache_changed = 0;
+ index_file_timestamp = 0;
+ cache_tree_free(&active_cache_tree);
+ if (cache_mmap == NULL)
+ return 0;
+ ret = munmap(cache_mmap, cache_mmap_size);
+ cache_mmap = NULL;
+ cache_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_cache(int newfd, struct cache_entry **cache, int entries)
+{
+ SHA_CTX c;
+ struct cache_header hdr;
+ int i, removed;
+
+ 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 (index_file_timestamp &&
+ index_file_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 (active_cache_tree) {
+ unsigned long sz;
+ void *data = cache_tree_write(active_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);
+}
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-22 11:20:04 +0000