From 74e34e1fca2ed9998581cc94073bc2dd28bbb8f3 Mon Sep 17 00:00:00 2001 From: Nicolas Pitre Date: Mon, 9 Apr 2007 01:06:35 -0400 Subject: [PATCH] sha1_file.c: learn about index version 2 With this patch, packs larger than 4GB are usable, even on a 32-bit machine (at least on Linux). If off_t is not large enough to deal with a large pack then die() is called instead of attempting to use the pack and producing garbage. This was tested with a 8GB pack specially created for the occasion on a 32-bit machine. Signed-off-by: Nicolas Pitre Signed-off-by: Junio C Hamano --- sha1_file.c | 118 +++++++++++++++++++++++++++++++++++++++------------- 1 file changed, 89 insertions(+), 29 deletions(-) diff --git a/sha1_file.c b/sha1_file.c index ebdd497ba..0be9737bd 100644 --- a/sha1_file.c +++ b/sha1_file.c @@ -437,7 +437,7 @@ 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 nr, i, *index; + uint32_t version, nr, i, *index; int fd = open(path, O_RDONLY); struct stat st; @@ -455,21 +455,23 @@ static int check_packed_git_idx(const char *path, struct packed_git *p) idx_map = xmmap(NULL, idx_size, PROT_READ, MAP_PRIVATE, fd, 0); close(fd); - /* a future index format would start with this, as older git - * binaries would fail the non-monotonic index check below. - * give a nicer warning to the user if we can. - */ hdr = idx_map; if (hdr->idx_signature == htonl(PACK_IDX_SIGNATURE)) { - munmap(idx_map, idx_size); - return error("index file %s is a newer version" - " and is not supported by this binary" - " (try upgrading GIT to a newer version)", - path); - } + version = ntohl(hdr->idx_version); + if (version < 2 || version > 2) { + munmap(idx_map, idx_size); + return error("index file %s is version %d" + " 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) { @@ -479,19 +481,48 @@ static int check_packed_git_idx(const char *path, struct packed_git *p) nr = n; } - /* - * 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 file size in %s", path); + 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 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; + if (idx_size < min_size || idx_size > min_size + (nr - 1)*8) { + munmap(idx_map, idx_size); + return error("wrong index file size in %s", path); + } + if (idx_size != min_size) { + /* make sure we can deal with large pack offsets */ + off_t x = 0x7fffffffUL, y = 0xffffffffUL; + if (x > (x + 1) || y > (y + 1)) { + munmap(idx_map, idx_size); + return error("pack too large for current definition of off_t in %s", path); + } + } } - p->index_version = 1; + p->index_version = version; p->index_data = idx_map; p->index_size = idx_size; p->num_objects = nr; @@ -1531,27 +1562,56 @@ const unsigned char *nth_packed_object_sha1(const struct packed_git *p, uint32_t n) { const unsigned char *index = p->index_data; - index += 4 * 256; if (n >= p->num_objects) return NULL; - return index + 24 * n + 4; + index += 4 * 256; + if (p->index_version == 1) { + return index + 24 * n + 4; + } else { + index += 8; + return index + 20 * n; + } +} + +static off_t nth_packed_object_offset(const struct packed_git *p, uint32_t n) +{ + const unsigned char *index = p->index_data; + index += 4 * 256; + if (p->index_version == 1) { + return ntohl(*((uint32_t *)(index + 24 * n))); + } else { + uint32_t off; + index += 8 + p->num_objects * (20 + 4); + off = ntohl(*((uint32_t *)(index + 4 * n))); + if (!(off & 0x80000000)) + return off; + index += p->num_objects * 4 + (off & 0x7fffffff) * 8; + return (((uint64_t)ntohl(*((uint32_t *)(index + 0)))) << 32) | + ntohl(*((uint32_t *)(index + 4))); + } } off_t find_pack_entry_one(const unsigned char *sha1, struct packed_git *p) { const uint32_t *level1_ofs = p->index_data; - int hi = ntohl(level1_ofs[*sha1]); - int lo = ((*sha1 == 0x0) ? 0 : ntohl(level1_ofs[*sha1 - 1])); const unsigned char *index = p->index_data; + unsigned hi, lo; + if (p->index_version > 1) { + level1_ofs += 2; + index += 8; + } index += 4 * 256; + hi = ntohl(level1_ofs[*sha1]); + lo = ((*sha1 == 0x0) ? 0 : ntohl(level1_ofs[*sha1 - 1])); do { - int mi = (lo + hi) / 2; - int cmp = hashcmp(index + 24 * mi + 4, sha1); + unsigned mi = (lo + hi) / 2; + unsigned x = (p->index_version > 1) ? (mi * 20) : (mi * 24 + 4); + int cmp = hashcmp(index + x, sha1); if (!cmp) - return ntohl(*((uint32_t *)((char *)index + (24 * mi)))); + return nth_packed_object_offset(p, mi); if (cmp > 0) hi = mi; else -- 2.26.2