diff options
| -rw-r--r-- | cache.h | 3 | ||||
| -rw-r--r-- | read-cache.c | 47 | ||||
| -rw-r--r-- | wrapper.c | 20 |
3 files changed, 69 insertions, 1 deletions
@@ -279,6 +279,7 @@ struct index_state { initialized : 1; struct hash_table name_hash; struct hash_table dir_hash; + unsigned char sha1[20]; }; extern struct index_state the_index; @@ -1199,6 +1200,8 @@ extern void fsync_or_die(int fd, const char *); extern ssize_t read_in_full(int fd, void *buf, size_t count); extern ssize_t write_in_full(int fd, const void *buf, size_t count); +extern ssize_t pread_in_full(int fd, void *buf, size_t count, off_t offset); + static inline ssize_t write_str_in_full(int fd, const char *str) { return write_in_full(fd, str, strlen(str)); diff --git a/read-cache.c b/read-cache.c index 33dd676ccb..f4a0d6168b 100644 --- a/read-cache.c +++ b/read-cache.c @@ -1464,6 +1464,7 @@ int read_index_from(struct index_state *istate, const char *path) if (verify_hdr(hdr, mmap_size) < 0) goto unmap; + hashcpy(istate->sha1, (unsigned char *)hdr + mmap_size - 20); istate->version = ntohl(hdr->hdr_version); istate->cache_nr = ntohl(hdr->hdr_entries); istate->cache_alloc = alloc_nr(istate->cache_nr); @@ -1747,6 +1748,50 @@ static int ce_write_entry(git_SHA_CTX *c, int fd, struct cache_entry *ce, return result; } +/* + * This function verifies if index_state has the correct sha1 of the + * index file. Don't die if we have any other failure, just return 0. + */ +static int verify_index_from(const struct index_state *istate, const char *path) +{ + int fd; + ssize_t n; + struct stat st; + unsigned char sha1[20]; + + if (!istate->initialized) + return 0; + + fd = open(path, O_RDONLY); + if (fd < 0) + return 0; + + if (fstat(fd, &st)) + goto out; + + if (st.st_size < sizeof(struct cache_header) + 20) + goto out; + + n = pread_in_full(fd, sha1, 20, st.st_size - 20); + if (n != 20) + goto out; + + if (hashcmp(istate->sha1, sha1)) + goto out; + + close(fd); + return 1; + +out: + close(fd); + return 0; +} + +static int verify_index(const struct index_state *istate) +{ + return verify_index_from(istate, get_index_file()); +} + static int has_racy_timestamp(struct index_state *istate) { int entries = istate->cache_nr; @@ -1766,7 +1811,7 @@ static int has_racy_timestamp(struct index_state *istate) void update_index_if_able(struct index_state *istate, struct lock_file *lockfile) { if ((istate->cache_changed || has_racy_timestamp(istate)) && - !write_index(istate, lockfile->fd)) + verify_index(istate) && !write_index(istate, lockfile->fd)) commit_locked_index(lockfile); else rollback_lock_file(lockfile); @@ -232,6 +232,26 @@ ssize_t write_in_full(int fd, const void *buf, size_t count) return total; } +ssize_t pread_in_full(int fd, void *buf, size_t count, off_t offset) +{ + char *p = buf; + ssize_t total = 0; + + while (count > 0) { + ssize_t loaded = xpread(fd, p, count, offset); + if (loaded < 0) + return -1; + if (loaded == 0) + return total; + count -= loaded; + p += loaded; + total += loaded; + offset += loaded; + } + + return total; +} + int xdup(int fd) { int ret = dup(fd); |