Squashed 'third_party/git/' content from commit cb71568594
git-subtree-dir: third_party/git git-subtree-split: cb715685942260375e1eb8153b0768a376e4ece7
This commit is contained in:
Vincent Ambo
commit
1b593e1ea4
3629 changed files with 1139935 additions and 0 deletions
379
pack-write.c
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379
pack-write.c
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#include "cache.h"
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#include "pack.h"
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#include "csum-file.h"
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void reset_pack_idx_option(struct pack_idx_option *opts)
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{
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memset(opts, 0, sizeof(*opts));
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opts->version = 2;
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opts->off32_limit = 0x7fffffff;
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}
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static int sha1_compare(const void *_a, const void *_b)
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{
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struct pack_idx_entry *a = *(struct pack_idx_entry **)_a;
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struct pack_idx_entry *b = *(struct pack_idx_entry **)_b;
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return oidcmp(&a->oid, &b->oid);
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}
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static int cmp_uint32(const void *a_, const void *b_)
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{
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uint32_t a = *((uint32_t *)a_);
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uint32_t b = *((uint32_t *)b_);
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return (a < b) ? -1 : (a != b);
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}
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static int need_large_offset(off_t offset, const struct pack_idx_option *opts)
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{
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uint32_t ofsval;
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if ((offset >> 31) || (opts->off32_limit < offset))
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return 1;
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if (!opts->anomaly_nr)
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return 0;
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ofsval = offset;
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return !!bsearch(&ofsval, opts->anomaly, opts->anomaly_nr,
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sizeof(ofsval), cmp_uint32);
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}
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/*
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* On entry *sha1 contains the pack content SHA1 hash, on exit it is
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* the SHA1 hash of sorted object names. The objects array passed in
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* will be sorted by SHA1 on exit.
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*/
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const char *write_idx_file(const char *index_name, struct pack_idx_entry **objects,
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int nr_objects, const struct pack_idx_option *opts,
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const unsigned char *sha1)
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{
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struct hashfile *f;
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struct pack_idx_entry **sorted_by_sha, **list, **last;
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off_t last_obj_offset = 0;
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uint32_t array[256];
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int i, fd;
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uint32_t index_version;
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if (nr_objects) {
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sorted_by_sha = objects;
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list = sorted_by_sha;
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last = sorted_by_sha + nr_objects;
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for (i = 0; i < nr_objects; ++i) {
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if (objects[i]->offset > last_obj_offset)
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last_obj_offset = objects[i]->offset;
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}
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QSORT(sorted_by_sha, nr_objects, sha1_compare);
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}
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else
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sorted_by_sha = list = last = NULL;
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if (opts->flags & WRITE_IDX_VERIFY) {
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assert(index_name);
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f = hashfd_check(index_name);
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} else {
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if (!index_name) {
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struct strbuf tmp_file = STRBUF_INIT;
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fd = odb_mkstemp(&tmp_file, "pack/tmp_idx_XXXXXX");
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index_name = strbuf_detach(&tmp_file, NULL);
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} else {
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unlink(index_name);
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fd = open(index_name, O_CREAT|O_EXCL|O_WRONLY, 0600);
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if (fd < 0)
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die_errno("unable to create '%s'", index_name);
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}
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f = hashfd(fd, index_name);
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}
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/* if last object's offset is >= 2^31 we should use index V2 */
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index_version = need_large_offset(last_obj_offset, opts) ? 2 : opts->version;
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/* index versions 2 and above need a header */
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if (index_version >= 2) {
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struct pack_idx_header hdr;
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hdr.idx_signature = htonl(PACK_IDX_SIGNATURE);
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hdr.idx_version = htonl(index_version);
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hashwrite(f, &hdr, sizeof(hdr));
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}
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/*
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* Write the first-level table (the list is sorted,
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* but we use a 256-entry lookup to be able to avoid
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* having to do eight extra binary search iterations).
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*/
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for (i = 0; i < 256; i++) {
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struct pack_idx_entry **next = list;
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while (next < last) {
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struct pack_idx_entry *obj = *next;
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if (obj->oid.hash[0] != i)
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break;
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next++;
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}
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array[i] = htonl(next - sorted_by_sha);
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list = next;
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}
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hashwrite(f, array, 256 * 4);
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/*
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* Write the actual SHA1 entries..
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*/
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list = sorted_by_sha;
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for (i = 0; i < nr_objects; i++) {
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struct pack_idx_entry *obj = *list++;
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if (index_version < 2) {
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uint32_t offset = htonl(obj->offset);
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hashwrite(f, &offset, 4);
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}
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hashwrite(f, obj->oid.hash, the_hash_algo->rawsz);
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if ((opts->flags & WRITE_IDX_STRICT) &&
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(i && oideq(&list[-2]->oid, &obj->oid)))
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die("The same object %s appears twice in the pack",
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oid_to_hex(&obj->oid));
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}
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if (index_version >= 2) {
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unsigned int nr_large_offset = 0;
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/* write the crc32 table */
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list = sorted_by_sha;
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for (i = 0; i < nr_objects; i++) {
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struct pack_idx_entry *obj = *list++;
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uint32_t crc32_val = htonl(obj->crc32);
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hashwrite(f, &crc32_val, 4);
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}
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/* write the 32-bit offset table */
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list = sorted_by_sha;
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for (i = 0; i < nr_objects; i++) {
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struct pack_idx_entry *obj = *list++;
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uint32_t offset;
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offset = (need_large_offset(obj->offset, opts)
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? (0x80000000 | nr_large_offset++)
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: obj->offset);
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offset = htonl(offset);
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hashwrite(f, &offset, 4);
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}
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/* write the large offset table */
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list = sorted_by_sha;
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while (nr_large_offset) {
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struct pack_idx_entry *obj = *list++;
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uint64_t offset = obj->offset;
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uint32_t split[2];
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if (!need_large_offset(offset, opts))
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continue;
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split[0] = htonl(offset >> 32);
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split[1] = htonl(offset & 0xffffffff);
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hashwrite(f, split, 8);
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nr_large_offset--;
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}
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}
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hashwrite(f, sha1, the_hash_algo->rawsz);
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finalize_hashfile(f, NULL, CSUM_HASH_IN_STREAM | CSUM_CLOSE |
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((opts->flags & WRITE_IDX_VERIFY)
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? 0 : CSUM_FSYNC));
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return index_name;
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}
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off_t write_pack_header(struct hashfile *f, uint32_t nr_entries)
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{
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struct pack_header hdr;
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hdr.hdr_signature = htonl(PACK_SIGNATURE);
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hdr.hdr_version = htonl(PACK_VERSION);
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hdr.hdr_entries = htonl(nr_entries);
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hashwrite(f, &hdr, sizeof(hdr));
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return sizeof(hdr);
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}
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/*
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* Update pack header with object_count and compute new SHA1 for pack data
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* associated to pack_fd, and write that SHA1 at the end. That new SHA1
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* is also returned in new_pack_sha1.
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*
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* If partial_pack_sha1 is non null, then the SHA1 of the existing pack
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* (without the header update) is computed and validated against the
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* one provided in partial_pack_sha1. The validation is performed at
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* partial_pack_offset bytes in the pack file. The SHA1 of the remaining
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* data (i.e. from partial_pack_offset to the end) is then computed and
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* returned in partial_pack_sha1.
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*
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* Note that new_pack_sha1 is updated last, so both new_pack_sha1 and
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* partial_pack_sha1 can refer to the same buffer if the caller is not
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* interested in the resulting SHA1 of pack data above partial_pack_offset.
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*/
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void fixup_pack_header_footer(int pack_fd,
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unsigned char *new_pack_hash,
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const char *pack_name,
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uint32_t object_count,
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unsigned char *partial_pack_hash,
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off_t partial_pack_offset)
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{
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int aligned_sz, buf_sz = 8 * 1024;
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git_hash_ctx old_hash_ctx, new_hash_ctx;
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struct pack_header hdr;
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char *buf;
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ssize_t read_result;
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the_hash_algo->init_fn(&old_hash_ctx);
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the_hash_algo->init_fn(&new_hash_ctx);
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if (lseek(pack_fd, 0, SEEK_SET) != 0)
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die_errno("Failed seeking to start of '%s'", pack_name);
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read_result = read_in_full(pack_fd, &hdr, sizeof(hdr));
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if (read_result < 0)
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die_errno("Unable to reread header of '%s'", pack_name);
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else if (read_result != sizeof(hdr))
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die_errno("Unexpected short read for header of '%s'",
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pack_name);
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if (lseek(pack_fd, 0, SEEK_SET) != 0)
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die_errno("Failed seeking to start of '%s'", pack_name);
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the_hash_algo->update_fn(&old_hash_ctx, &hdr, sizeof(hdr));
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hdr.hdr_entries = htonl(object_count);
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the_hash_algo->update_fn(&new_hash_ctx, &hdr, sizeof(hdr));
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write_or_die(pack_fd, &hdr, sizeof(hdr));
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partial_pack_offset -= sizeof(hdr);
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buf = xmalloc(buf_sz);
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aligned_sz = buf_sz - sizeof(hdr);
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for (;;) {
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ssize_t m, n;
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m = (partial_pack_hash && partial_pack_offset < aligned_sz) ?
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partial_pack_offset : aligned_sz;
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n = xread(pack_fd, buf, m);
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if (!n)
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break;
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if (n < 0)
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die_errno("Failed to checksum '%s'", pack_name);
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the_hash_algo->update_fn(&new_hash_ctx, buf, n);
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aligned_sz -= n;
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if (!aligned_sz)
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aligned_sz = buf_sz;
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if (!partial_pack_hash)
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continue;
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the_hash_algo->update_fn(&old_hash_ctx, buf, n);
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partial_pack_offset -= n;
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if (partial_pack_offset == 0) {
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unsigned char hash[GIT_MAX_RAWSZ];
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the_hash_algo->final_fn(hash, &old_hash_ctx);
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if (!hasheq(hash, partial_pack_hash))
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die("Unexpected checksum for %s "
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"(disk corruption?)", pack_name);
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/*
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* Now let's compute the SHA1 of the remainder of the
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* pack, which also means making partial_pack_offset
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* big enough not to matter anymore.
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*/
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the_hash_algo->init_fn(&old_hash_ctx);
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partial_pack_offset = ~partial_pack_offset;
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partial_pack_offset -= MSB(partial_pack_offset, 1);
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}
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}
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free(buf);
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if (partial_pack_hash)
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the_hash_algo->final_fn(partial_pack_hash, &old_hash_ctx);
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the_hash_algo->final_fn(new_pack_hash, &new_hash_ctx);
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write_or_die(pack_fd, new_pack_hash, the_hash_algo->rawsz);
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fsync_or_die(pack_fd, pack_name);
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}
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char *index_pack_lockfile(int ip_out)
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{
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char packname[GIT_MAX_HEXSZ + 6];
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const int len = the_hash_algo->hexsz + 6;
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/*
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* The first thing we expect from index-pack's output
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* is "pack\t%40s\n" or "keep\t%40s\n" (46 bytes) where
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* %40s is the newly created pack SHA1 name. In the "keep"
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* case, we need it to remove the corresponding .keep file
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* later on. If we don't get that then tough luck with it.
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*/
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if (read_in_full(ip_out, packname, len) == len && packname[len-1] == '\n') {
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const char *name;
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packname[len-1] = 0;
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if (skip_prefix(packname, "keep\t", &name))
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return xstrfmt("%s/pack/pack-%s.keep",
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get_object_directory(), name);
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}
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return NULL;
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}
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/*
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* The per-object header is a pretty dense thing, which is
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* - first byte: low four bits are "size", then three bits of "type",
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* and the high bit is "size continues".
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* - each byte afterwards: low seven bits are size continuation,
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* with the high bit being "size continues"
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*/
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int encode_in_pack_object_header(unsigned char *hdr, int hdr_len,
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enum object_type type, uintmax_t size)
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{
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int n = 1;
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unsigned char c;
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if (type < OBJ_COMMIT || type > OBJ_REF_DELTA)
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die("bad type %d", type);
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c = (type << 4) | (size & 15);
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size >>= 4;
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while (size) {
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if (n == hdr_len)
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die("object size is too enormous to format");
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*hdr++ = c | 0x80;
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c = size & 0x7f;
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size >>= 7;
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n++;
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}
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*hdr = c;
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return n;
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}
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struct hashfile *create_tmp_packfile(char **pack_tmp_name)
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{
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struct strbuf tmpname = STRBUF_INIT;
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int fd;
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fd = odb_mkstemp(&tmpname, "pack/tmp_pack_XXXXXX");
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*pack_tmp_name = strbuf_detach(&tmpname, NULL);
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return hashfd(fd, *pack_tmp_name);
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}
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void finish_tmp_packfile(struct strbuf *name_buffer,
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const char *pack_tmp_name,
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struct pack_idx_entry **written_list,
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uint32_t nr_written,
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struct pack_idx_option *pack_idx_opts,
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unsigned char sha1[])
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{
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const char *idx_tmp_name;
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int basename_len = name_buffer->len;
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if (adjust_shared_perm(pack_tmp_name))
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die_errno("unable to make temporary pack file readable");
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idx_tmp_name = write_idx_file(NULL, written_list, nr_written,
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pack_idx_opts, sha1);
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if (adjust_shared_perm(idx_tmp_name))
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die_errno("unable to make temporary index file readable");
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strbuf_addf(name_buffer, "%s.pack", sha1_to_hex(sha1));
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if (rename(pack_tmp_name, name_buffer->buf))
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die_errno("unable to rename temporary pack file");
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strbuf_setlen(name_buffer, basename_len);
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strbuf_addf(name_buffer, "%s.idx", sha1_to_hex(sha1));
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if (rename(idx_tmp_name, name_buffer->buf))
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die_errno("unable to rename temporary index file");
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strbuf_setlen(name_buffer, basename_len);
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free((void *)idx_tmp_name);
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}
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