diff options
Diffstat (limited to 'pack-write.c')
| -rw-r--r-- | pack-write.c | 181 |
1 files changed, 181 insertions, 0 deletions
diff --git a/pack-write.c b/pack-write.c new file mode 100644 index 0000000..1cf5f7c --- /dev/null +++ b/pack-write.c @@ -0,0 +1,181 @@ +#include "cache.h" +#include "pack.h" +#include "csum-file.h" + +uint32_t pack_idx_default_version = 1; +uint32_t pack_idx_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 hashcmp(a->sha1, b->sha1); +} + +/* + * 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, unsigned char *sha1) +{ + struct sha1file *f; + struct pack_idx_entry **sorted_by_sha, **list, **last; + off_t last_obj_offset = 0; + uint32_t array[256]; + int i, fd; + SHA_CTX ctx; + 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, sizeof(sorted_by_sha[0]), + sha1_compare); + } + else + sorted_by_sha = list = last = NULL; + + if (!index_name) { + static char tmpfile[PATH_MAX]; + snprintf(tmpfile, sizeof(tmpfile), + "%s/tmp_idx_XXXXXX", get_object_directory()); + fd = mkstemp(tmpfile); + index_name = xstrdup(tmpfile); + } else { + unlink(index_name); + fd = open(index_name, O_CREAT|O_EXCL|O_WRONLY, 0600); + } + if (fd < 0) + die("unable to create %s: %s", index_name, strerror(errno)); + f = sha1fd(fd, index_name); + + /* if last object's offset is >= 2^31 we should use index V2 */ + index_version = (last_obj_offset >> 31) ? 2 : pack_idx_default_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); + sha1write(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->sha1[0] != i) + break; + next++; + } + array[i] = htonl(next - sorted_by_sha); + list = next; + } + sha1write(f, array, 256 * 4); + + /* compute the SHA1 hash of sorted object names. */ + SHA1_Init(&ctx); + + /* + * 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); + sha1write(f, &offset, 4); + } + sha1write(f, obj->sha1, 20); + SHA1_Update(&ctx, obj->sha1, 20); + } + + 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); + sha1write(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 = (obj->offset <= pack_idx_off32_limit) ? + obj->offset : (0x80000000 | nr_large_offset++); + offset = htonl(offset); + sha1write(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; + if (offset > pack_idx_off32_limit) { + uint32_t split[2]; + split[0] = htonl(offset >> 32); + split[1] = htonl(offset & 0xffffffff); + sha1write(f, split, 8); + nr_large_offset--; + } + } + } + + sha1write(f, sha1, 20); + sha1close(f, NULL, 1); + SHA1_Final(sha1, &ctx); + return index_name; +} + +void fixup_pack_header_footer(int pack_fd, + unsigned char *pack_file_sha1, + const char *pack_name, + uint32_t object_count) +{ + static const int buf_sz = 128 * 1024; + SHA_CTX c; + struct pack_header hdr; + char *buf; + + if (lseek(pack_fd, 0, SEEK_SET) != 0) + die("Failed seeking to start: %s", strerror(errno)); + if (read_in_full(pack_fd, &hdr, sizeof(hdr)) != sizeof(hdr)) + die("Unable to reread header of %s: %s", pack_name, strerror(errno)); + if (lseek(pack_fd, 0, SEEK_SET) != 0) + die("Failed seeking to start: %s", strerror(errno)); + hdr.hdr_entries = htonl(object_count); + write_or_die(pack_fd, &hdr, sizeof(hdr)); + + SHA1_Init(&c); + SHA1_Update(&c, &hdr, sizeof(hdr)); + + buf = xmalloc(buf_sz); + for (;;) { + ssize_t n = xread(pack_fd, buf, buf_sz); + if (!n) + break; + if (n < 0) + die("Failed to checksum %s: %s", pack_name, strerror(errno)); + SHA1_Update(&c, buf, n); + } + free(buf); + + SHA1_Final(pack_file_sha1, &c); + write_or_die(pack_fd, pack_file_sha1, 20); +} |