diff options
Diffstat (limited to 'pack-write.c')
| -rw-r--r-- | pack-write.c | 379 |
1 files changed, 379 insertions, 0 deletions
diff --git a/pack-write.c b/pack-write.c new file mode 100644 index 0000000000..29d17a9bec --- /dev/null +++ b/pack-write.c @@ -0,0 +1,379 @@ +#include "cache.h" +#include "pack.h" +#include "csum-file.h" + +void reset_pack_idx_option(struct pack_idx_option *opts) +{ + memset(opts, 0, sizeof(*opts)); + opts->version = 2; + opts->off32_limit = 0x7fffffff; +} + +static int sha1_compare(const void *_a, const void *_b) +{ + struct pack_idx_entry *a = *(struct pack_idx_entry **)_a; + struct pack_idx_entry *b = *(struct pack_idx_entry **)_b; + return oidcmp(&a->oid, &b->oid); +} + +static int cmp_uint32(const void *a_, const void *b_) +{ + uint32_t a = *((uint32_t *)a_); + uint32_t b = *((uint32_t *)b_); + + return (a < b) ? -1 : (a != b); +} + +static int need_large_offset(off_t offset, const struct pack_idx_option *opts) +{ + uint32_t ofsval; + + if ((offset >> 31) || (opts->off32_limit < offset)) + return 1; + if (!opts->anomaly_nr) + return 0; + ofsval = offset; + return !!bsearch(&ofsval, opts->anomaly, opts->anomaly_nr, + sizeof(ofsval), cmp_uint32); +} + +/* + * On entry *sha1 contains the pack content SHA1 hash, on exit it is + * the SHA1 hash of sorted object names. The objects array passed in + * will be sorted by SHA1 on exit. + */ +const char *write_idx_file(const char *index_name, struct pack_idx_entry **objects, + int nr_objects, const struct pack_idx_option *opts, + const unsigned char *sha1) +{ + struct hashfile *f; + struct pack_idx_entry **sorted_by_sha, **list, **last; + off_t last_obj_offset = 0; + uint32_t array[256]; + int i, fd; + uint32_t index_version; + + if (nr_objects) { + sorted_by_sha = objects; + list = sorted_by_sha; + last = sorted_by_sha + nr_objects; + for (i = 0; i < nr_objects; ++i) { + if (objects[i]->offset > last_obj_offset) + last_obj_offset = objects[i]->offset; + } + QSORT(sorted_by_sha, nr_objects, sha1_compare); + } + else + sorted_by_sha = list = last = NULL; + + if (opts->flags & WRITE_IDX_VERIFY) { + assert(index_name); + f = hashfd_check(index_name); + } else { + if (!index_name) { + struct strbuf tmp_file = STRBUF_INIT; + fd = odb_mkstemp(&tmp_file, "pack/tmp_idx_XXXXXX"); + index_name = strbuf_detach(&tmp_file, NULL); + } else { + unlink(index_name); + fd = open(index_name, O_CREAT|O_EXCL|O_WRONLY, 0600); + if (fd < 0) + die_errno("unable to create '%s'", index_name); + } + f = hashfd(fd, index_name); + } + + /* if last object's offset is >= 2^31 we should use index V2 */ + index_version = need_large_offset(last_obj_offset, opts) ? 2 : opts->version; + + /* index versions 2 and above need a header */ + if (index_version >= 2) { + struct pack_idx_header hdr; + hdr.idx_signature = htonl(PACK_IDX_SIGNATURE); + hdr.idx_version = htonl(index_version); + hashwrite(f, &hdr, sizeof(hdr)); + } + + /* + * Write the first-level table (the list is sorted, + * but we use a 256-entry lookup to be able to avoid + * having to do eight extra binary search iterations). + */ + for (i = 0; i < 256; i++) { + struct pack_idx_entry **next = list; + while (next < last) { + struct pack_idx_entry *obj = *next; + if (obj->oid.hash[0] != i) + break; + next++; + } + array[i] = htonl(next - sorted_by_sha); + list = next; + } + hashwrite(f, array, 256 * 4); + + /* + * Write the actual SHA1 entries.. + */ + list = sorted_by_sha; + for (i = 0; i < nr_objects; i++) { + struct pack_idx_entry *obj = *list++; + if (index_version < 2) { + uint32_t offset = htonl(obj->offset); + hashwrite(f, &offset, 4); + } + hashwrite(f, obj->oid.hash, the_hash_algo->rawsz); + if ((opts->flags & WRITE_IDX_STRICT) && + (i && oideq(&list[-2]->oid, &obj->oid))) + die("The same object %s appears twice in the pack", + oid_to_hex(&obj->oid)); + } + + if (index_version >= 2) { + unsigned int nr_large_offset = 0; + + /* write the crc32 table */ + list = sorted_by_sha; + for (i = 0; i < nr_objects; i++) { + struct pack_idx_entry *obj = *list++; + uint32_t crc32_val = htonl(obj->crc32); + hashwrite(f, &crc32_val, 4); + } + + /* write the 32-bit offset table */ + list = sorted_by_sha; + for (i = 0; i < nr_objects; i++) { + struct pack_idx_entry *obj = *list++; + uint32_t offset; + + offset = (need_large_offset(obj->offset, opts) + ? (0x80000000 | nr_large_offset++) + : obj->offset); + offset = htonl(offset); + hashwrite(f, &offset, 4); + } + + /* write the large offset table */ + list = sorted_by_sha; + while (nr_large_offset) { + struct pack_idx_entry *obj = *list++; + uint64_t offset = obj->offset; + uint32_t split[2]; + + if (!need_large_offset(offset, opts)) + continue; + split[0] = htonl(offset >> 32); + split[1] = htonl(offset & 0xffffffff); + hashwrite(f, split, 8); + nr_large_offset--; + } + } + + hashwrite(f, sha1, the_hash_algo->rawsz); + finalize_hashfile(f, NULL, CSUM_HASH_IN_STREAM | CSUM_CLOSE | + ((opts->flags & WRITE_IDX_VERIFY) + ? 0 : CSUM_FSYNC)); + return index_name; +} + +off_t write_pack_header(struct hashfile *f, uint32_t nr_entries) +{ + struct pack_header hdr; + + hdr.hdr_signature = htonl(PACK_SIGNATURE); + hdr.hdr_version = htonl(PACK_VERSION); + hdr.hdr_entries = htonl(nr_entries); + hashwrite(f, &hdr, sizeof(hdr)); + return sizeof(hdr); +} + +/* + * Update pack header with object_count and compute new SHA1 for pack data + * associated to pack_fd, and write that SHA1 at the end. That new SHA1 + * is also returned in new_pack_sha1. + * + * If partial_pack_sha1 is non null, then the SHA1 of the existing pack + * (without the header update) is computed and validated against the + * one provided in partial_pack_sha1. The validation is performed at + * partial_pack_offset bytes in the pack file. The SHA1 of the remaining + * data (i.e. from partial_pack_offset to the end) is then computed and + * returned in partial_pack_sha1. + * + * Note that new_pack_sha1 is updated last, so both new_pack_sha1 and + * partial_pack_sha1 can refer to the same buffer if the caller is not + * interested in the resulting SHA1 of pack data above partial_pack_offset. + */ +void fixup_pack_header_footer(int pack_fd, + unsigned char *new_pack_hash, + const char *pack_name, + uint32_t object_count, + unsigned char *partial_pack_hash, + off_t partial_pack_offset) +{ + int aligned_sz, buf_sz = 8 * 1024; + git_hash_ctx old_hash_ctx, new_hash_ctx; + struct pack_header hdr; + char *buf; + ssize_t read_result; + + the_hash_algo->init_fn(&old_hash_ctx); + the_hash_algo->init_fn(&new_hash_ctx); + + if (lseek(pack_fd, 0, SEEK_SET) != 0) + die_errno("Failed seeking to start of '%s'", pack_name); + read_result = read_in_full(pack_fd, &hdr, sizeof(hdr)); + if (read_result < 0) + die_errno("Unable to reread header of '%s'", pack_name); + else if (read_result != sizeof(hdr)) + die_errno("Unexpected short read for header of '%s'", + pack_name); + if (lseek(pack_fd, 0, SEEK_SET) != 0) + die_errno("Failed seeking to start of '%s'", pack_name); + the_hash_algo->update_fn(&old_hash_ctx, &hdr, sizeof(hdr)); + hdr.hdr_entries = htonl(object_count); + the_hash_algo->update_fn(&new_hash_ctx, &hdr, sizeof(hdr)); + write_or_die(pack_fd, &hdr, sizeof(hdr)); + partial_pack_offset -= sizeof(hdr); + + buf = xmalloc(buf_sz); + aligned_sz = buf_sz - sizeof(hdr); + for (;;) { + ssize_t m, n; + m = (partial_pack_hash && partial_pack_offset < aligned_sz) ? + partial_pack_offset : aligned_sz; + n = xread(pack_fd, buf, m); + if (!n) + break; + if (n < 0) + die_errno("Failed to checksum '%s'", pack_name); + the_hash_algo->update_fn(&new_hash_ctx, buf, n); + + aligned_sz -= n; + if (!aligned_sz) + aligned_sz = buf_sz; + + if (!partial_pack_hash) + continue; + + the_hash_algo->update_fn(&old_hash_ctx, buf, n); + partial_pack_offset -= n; + if (partial_pack_offset == 0) { + unsigned char hash[GIT_MAX_RAWSZ]; + the_hash_algo->final_fn(hash, &old_hash_ctx); + if (!hasheq(hash, partial_pack_hash)) + die("Unexpected checksum for %s " + "(disk corruption?)", pack_name); + /* + * Now let's compute the SHA1 of the remainder of the + * pack, which also means making partial_pack_offset + * big enough not to matter anymore. + */ + the_hash_algo->init_fn(&old_hash_ctx); + partial_pack_offset = ~partial_pack_offset; + partial_pack_offset -= MSB(partial_pack_offset, 1); + } + } + free(buf); + + if (partial_pack_hash) + the_hash_algo->final_fn(partial_pack_hash, &old_hash_ctx); + the_hash_algo->final_fn(new_pack_hash, &new_hash_ctx); + write_or_die(pack_fd, new_pack_hash, the_hash_algo->rawsz); + fsync_or_die(pack_fd, pack_name); +} + +char *index_pack_lockfile(int ip_out) +{ + char packname[GIT_MAX_HEXSZ + 6]; + const int len = the_hash_algo->hexsz + 6; + + /* + * The first thing we expect from index-pack's output + * is "pack\t%40s\n" or "keep\t%40s\n" (46 bytes) where + * %40s is the newly created pack SHA1 name. In the "keep" + * case, we need it to remove the corresponding .keep file + * later on. If we don't get that then tough luck with it. + */ + if (read_in_full(ip_out, packname, len) == len && packname[len-1] == '\n') { + const char *name; + packname[len-1] = 0; + if (skip_prefix(packname, "keep\t", &name)) + return xstrfmt("%s/pack/pack-%s.keep", + get_object_directory(), name); + } + return NULL; +} + +/* + * The per-object header is a pretty dense thing, which is + * - first byte: low four bits are "size", then three bits of "type", + * and the high bit is "size continues". + * - each byte afterwards: low seven bits are size continuation, + * with the high bit being "size continues" + */ +int encode_in_pack_object_header(unsigned char *hdr, int hdr_len, + enum object_type type, uintmax_t size) +{ + int n = 1; + unsigned char c; + + if (type < OBJ_COMMIT || type > OBJ_REF_DELTA) + die("bad type %d", type); + + c = (type << 4) | (size & 15); + size >>= 4; + while (size) { + if (n == hdr_len) + die("object size is too enormous to format"); + *hdr++ = c | 0x80; + c = size & 0x7f; + size >>= 7; + n++; + } + *hdr = c; + return n; +} + +struct hashfile *create_tmp_packfile(char **pack_tmp_name) +{ + struct strbuf tmpname = STRBUF_INIT; + int fd; + + fd = odb_mkstemp(&tmpname, "pack/tmp_pack_XXXXXX"); + *pack_tmp_name = strbuf_detach(&tmpname, NULL); + return hashfd(fd, *pack_tmp_name); +} + +void finish_tmp_packfile(struct strbuf *name_buffer, + const char *pack_tmp_name, + struct pack_idx_entry **written_list, + uint32_t nr_written, + struct pack_idx_option *pack_idx_opts, + unsigned char sha1[]) +{ + const char *idx_tmp_name; + int basename_len = name_buffer->len; + + if (adjust_shared_perm(pack_tmp_name)) + die_errno("unable to make temporary pack file readable"); + + idx_tmp_name = write_idx_file(NULL, written_list, nr_written, + pack_idx_opts, sha1); + if (adjust_shared_perm(idx_tmp_name)) + die_errno("unable to make temporary index file readable"); + + strbuf_addf(name_buffer, "%s.pack", sha1_to_hex(sha1)); + + if (rename(pack_tmp_name, name_buffer->buf)) + die_errno("unable to rename temporary pack file"); + + strbuf_setlen(name_buffer, basename_len); + + strbuf_addf(name_buffer, "%s.idx", sha1_to_hex(sha1)); + if (rename(idx_tmp_name, name_buffer->buf)) + die_errno("unable to rename temporary index file"); + + strbuf_setlen(name_buffer, basename_len); + + free((void *)idx_tmp_name); +} |