diff options
Diffstat (limited to 'packfile.c')
-rw-r--r-- | packfile.c | 149 |
1 files changed, 149 insertions, 0 deletions
diff --git a/packfile.c b/packfile.c index 60d9fc3b03..6edc432288 100644 --- a/packfile.c +++ b/packfile.c @@ -1,5 +1,6 @@ #include "cache.h" #include "mru.h" +#include "pack.h" char *odb_pack_name(struct strbuf *buf, const unsigned char *sha1, @@ -59,3 +60,151 @@ void pack_report(void) pack_open_windows, peak_pack_open_windows, sz_fmt(pack_mapped), sz_fmt(peak_pack_mapped)); } + +/* + * Open and mmap the index file at path, perform a couple of + * consistency checks, then record its information to p. Return 0 on + * success. + */ +static int check_packed_git_idx(const char *path, struct packed_git *p) +{ + void *idx_map; + struct pack_idx_header *hdr; + size_t idx_size; + uint32_t version, nr, i, *index; + int fd = git_open(path); + struct stat st; + + if (fd < 0) + return -1; + if (fstat(fd, &st)) { + close(fd); + return -1; + } + idx_size = xsize_t(st.st_size); + if (idx_size < 4 * 256 + 20 + 20) { + close(fd); + return error("index file %s is too small", path); + } + idx_map = xmmap(NULL, idx_size, PROT_READ, MAP_PRIVATE, fd, 0); + close(fd); + + hdr = idx_map; + if (hdr->idx_signature == htonl(PACK_IDX_SIGNATURE)) { + version = ntohl(hdr->idx_version); + if (version < 2 || version > 2) { + munmap(idx_map, idx_size); + return error("index file %s is version %"PRIu32 + " and is not supported by this binary" + " (try upgrading GIT to a newer version)", + path, version); + } + } else + version = 1; + + nr = 0; + index = idx_map; + if (version > 1) + index += 2; /* skip index header */ + for (i = 0; i < 256; i++) { + uint32_t n = ntohl(index[i]); + if (n < nr) { + munmap(idx_map, idx_size); + return error("non-monotonic index %s", path); + } + nr = n; + } + + if (version == 1) { + /* + * Total size: + * - 256 index entries 4 bytes each + * - 24-byte entries * nr (20-byte sha1 + 4-byte offset) + * - 20-byte SHA1 of the packfile + * - 20-byte SHA1 file checksum + */ + if (idx_size != 4*256 + nr * 24 + 20 + 20) { + munmap(idx_map, idx_size); + return error("wrong index v1 file size in %s", path); + } + } else if (version == 2) { + /* + * Minimum size: + * - 8 bytes of header + * - 256 index entries 4 bytes each + * - 20-byte sha1 entry * nr + * - 4-byte crc entry * nr + * - 4-byte offset entry * nr + * - 20-byte SHA1 of the packfile + * - 20-byte SHA1 file checksum + * And after the 4-byte offset table might be a + * variable sized table containing 8-byte entries + * for offsets larger than 2^31. + */ + unsigned long min_size = 8 + 4*256 + nr*(20 + 4 + 4) + 20 + 20; + unsigned long max_size = min_size; + if (nr) + max_size += (nr - 1)*8; + if (idx_size < min_size || idx_size > max_size) { + munmap(idx_map, idx_size); + return error("wrong index v2 file size in %s", path); + } + if (idx_size != min_size && + /* + * make sure we can deal with large pack offsets. + * 31-bit signed offset won't be enough, neither + * 32-bit unsigned one will be. + */ + (sizeof(off_t) <= 4)) { + munmap(idx_map, idx_size); + return error("pack too large for current definition of off_t in %s", path); + } + } + + p->index_version = version; + p->index_data = idx_map; + p->index_size = idx_size; + p->num_objects = nr; + return 0; +} + +int open_pack_index(struct packed_git *p) +{ + char *idx_name; + size_t len; + int ret; + + if (p->index_data) + return 0; + + if (!strip_suffix(p->pack_name, ".pack", &len)) + die("BUG: pack_name does not end in .pack"); + idx_name = xstrfmt("%.*s.idx", (int)len, p->pack_name); + ret = check_packed_git_idx(idx_name, p); + free(idx_name); + return ret; +} + +static struct packed_git *alloc_packed_git(int extra) +{ + struct packed_git *p = xmalloc(st_add(sizeof(*p), extra)); + memset(p, 0, sizeof(*p)); + p->pack_fd = -1; + return p; +} + +struct packed_git *parse_pack_index(unsigned char *sha1, const char *idx_path) +{ + const char *path = sha1_pack_name(sha1); + size_t alloc = st_add(strlen(path), 1); + struct packed_git *p = alloc_packed_git(alloc); + + memcpy(p->pack_name, path, alloc); /* includes NUL */ + hashcpy(p->sha1, sha1); + if (check_packed_git_idx(idx_path, p)) { + free(p); + return NULL; + } + + return p; +} |