diff options
Diffstat (limited to 'pack-check.c')
| -rw-r--r-- | pack-check.c | 161 |
1 files changed, 161 insertions, 0 deletions
diff --git a/pack-check.c b/pack-check.c new file mode 100644 index 000000000..f596bf2db --- /dev/null +++ b/pack-check.c @@ -0,0 +1,161 @@ +#include "cache.h" +#include "pack.h" +#include "pack-revindex.h" + +struct idx_entry +{ + off_t offset; + const unsigned char *sha1; + unsigned int nr; +}; + +static int compare_entries(const void *e1, const void *e2) +{ + const struct idx_entry *entry1 = e1; + const struct idx_entry *entry2 = e2; + if (entry1->offset < entry2->offset) + return -1; + if (entry1->offset > entry2->offset) + return 1; + return 0; +} + +int check_pack_crc(struct packed_git *p, struct pack_window **w_curs, + off_t offset, off_t len, unsigned int nr) +{ + const uint32_t *index_crc; + uint32_t data_crc = crc32(0, Z_NULL, 0); + + do { + unsigned int avail; + void *data = use_pack(p, w_curs, offset, &avail); + if (avail > len) + avail = len; + data_crc = crc32(data_crc, data, avail); + offset += avail; + len -= avail; + } while (len); + + index_crc = p->index_data; + index_crc += 2 + 256 + p->num_objects * (20/4) + nr; + + return data_crc != ntohl(*index_crc); +} + +static int verify_packfile(struct packed_git *p, + struct pack_window **w_curs) +{ + off_t index_size = p->index_size; + const unsigned char *index_base = p->index_data; + SHA_CTX ctx; + unsigned char sha1[20], *pack_sig; + off_t offset = 0, pack_sig_ofs = p->pack_size - 20; + uint32_t nr_objects, i; + int err = 0; + struct idx_entry *entries; + + /* Note that the pack header checks are actually performed by + * use_pack when it first opens the pack file. If anything + * goes wrong during those checks then the call will die out + * immediately. + */ + + SHA1_Init(&ctx); + while (offset < pack_sig_ofs) { + unsigned int remaining; + unsigned char *in = use_pack(p, w_curs, offset, &remaining); + offset += remaining; + if (offset > pack_sig_ofs) + remaining -= (unsigned int)(offset - pack_sig_ofs); + SHA1_Update(&ctx, in, remaining); + } + SHA1_Final(sha1, &ctx); + pack_sig = use_pack(p, w_curs, pack_sig_ofs, NULL); + if (hashcmp(sha1, pack_sig)) + err = error("%s SHA1 checksum mismatch", + p->pack_name); + if (hashcmp(index_base + index_size - 40, pack_sig)) + err = error("%s SHA1 does not match its inddex", + p->pack_name); + unuse_pack(w_curs); + + /* Make sure everything reachable from idx is valid. Since we + * have verified that nr_objects matches between idx and pack, + * we do not do scan-streaming check on the pack file. + */ + nr_objects = p->num_objects; + entries = xmalloc((nr_objects + 1) * sizeof(*entries)); + entries[nr_objects].offset = pack_sig_ofs; + /* first sort entries by pack offset, since unpacking them is more efficient that way */ + for (i = 0; i < nr_objects; i++) { + entries[i].sha1 = nth_packed_object_sha1(p, i); + if (!entries[i].sha1) + die("internal error pack-check nth-packed-object"); + entries[i].offset = nth_packed_object_offset(p, i); + entries[i].nr = i; + } + qsort(entries, nr_objects, sizeof(*entries), compare_entries); + + for (i = 0; i < nr_objects; i++) { + void *data; + enum object_type type; + unsigned long size; + + if (p->index_version > 1) { + off_t offset = entries[i].offset; + off_t len = entries[i+1].offset - offset; + unsigned int nr = entries[i].nr; + if (check_pack_crc(p, w_curs, offset, len, nr)) + err = error("index CRC mismatch for object %s " + "from %s at offset %"PRIuMAX"", + sha1_to_hex(entries[i].sha1), + p->pack_name, (uintmax_t)offset); + } + data = unpack_entry(p, entries[i].offset, &type, &size); + if (!data) { + err = error("cannot unpack %s from %s at offset %"PRIuMAX"", + sha1_to_hex(entries[i].sha1), p->pack_name, + (uintmax_t)entries[i].offset); + break; + } + if (check_sha1_signature(entries[i].sha1, data, size, typename(type))) { + err = error("packed %s from %s is corrupt", + sha1_to_hex(entries[i].sha1), p->pack_name); + free(data); + break; + } + free(data); + } + free(entries); + + return err; +} + +int verify_pack(struct packed_git *p) +{ + off_t index_size; + const unsigned char *index_base; + SHA_CTX ctx; + unsigned char sha1[20]; + int err = 0; + struct pack_window *w_curs = NULL; + + if (open_pack_index(p)) + return error("packfile %s index not opened", p->pack_name); + index_size = p->index_size; + index_base = p->index_data; + + /* Verify SHA1 sum of the index file */ + SHA1_Init(&ctx); + SHA1_Update(&ctx, index_base, (unsigned int)(index_size - 20)); + SHA1_Final(sha1, &ctx); + if (hashcmp(sha1, index_base + index_size - 20)) + err = error("Packfile index for %s SHA1 mismatch", + p->pack_name); + + /* Verify pack file */ + err |= verify_packfile(p, &w_curs); + unuse_pack(&w_curs); + + return err; +} |