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![Linus Torvalds](/assets/img/avatar_default.png)
This required some fairly trivial packfile function 'const' cleanup, since the builtin commands get a const char *argv[] array. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>
256 lines
7.3 KiB
C
256 lines
7.3 KiB
C
#include "cache.h"
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#include "pack.h"
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#include "csum-file.h"
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uint32_t pack_idx_default_version = 2;
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uint32_t pack_idx_off32_limit = 0x7fffffff;
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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 hashcmp(a->sha1, b->sha1);
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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, unsigned char *sha1)
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{
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struct sha1file *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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git_SHA_CTX ctx;
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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, sizeof(sorted_by_sha[0]),
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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 (!index_name) {
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static char tmpfile[PATH_MAX];
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fd = odb_mkstemp(tmpfile, sizeof(tmpfile), "pack/tmp_idx_XXXXXX");
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index_name = xstrdup(tmpfile);
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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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}
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if (fd < 0)
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die_errno("unable to create '%s'", index_name);
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f = sha1fd(fd, index_name);
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/* if last object's offset is >= 2^31 we should use index V2 */
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index_version = (last_obj_offset >> 31) ? 2 : pack_idx_default_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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sha1write(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->sha1[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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sha1write(f, array, 256 * 4);
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/* compute the SHA1 hash of sorted object names. */
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git_SHA1_Init(&ctx);
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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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sha1write(f, &offset, 4);
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}
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sha1write(f, obj->sha1, 20);
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git_SHA1_Update(&ctx, obj->sha1, 20);
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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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sha1write(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 = (obj->offset <= pack_idx_off32_limit) ?
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obj->offset : (0x80000000 | nr_large_offset++);
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offset = htonl(offset);
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sha1write(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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if (offset > pack_idx_off32_limit) {
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uint32_t split[2];
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split[0] = htonl(offset >> 32);
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split[1] = htonl(offset & 0xffffffff);
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sha1write(f, split, 8);
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nr_large_offset--;
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}
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}
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}
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sha1write(f, sha1, 20);
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sha1close(f, NULL, CSUM_FSYNC);
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git_SHA1_Final(sha1, &ctx);
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return index_name;
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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_sha1,
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const char *pack_name,
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uint32_t object_count,
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unsigned char *partial_pack_sha1,
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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_SHA_CTX old_sha1_ctx, new_sha1_ctx;
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struct pack_header hdr;
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char *buf;
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git_SHA1_Init(&old_sha1_ctx);
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git_SHA1_Init(&new_sha1_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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if (read_in_full(pack_fd, &hdr, sizeof(hdr)) != sizeof(hdr))
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die_errno("Unable to reread header of '%s'", 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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git_SHA1_Update(&old_sha1_ctx, &hdr, sizeof(hdr));
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hdr.hdr_entries = htonl(object_count);
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git_SHA1_Update(&new_sha1_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_sha1 && 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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git_SHA1_Update(&new_sha1_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_sha1)
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continue;
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git_SHA1_Update(&old_sha1_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 sha1[20];
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git_SHA1_Final(sha1, &old_sha1_ctx);
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if (hashcmp(sha1, partial_pack_sha1) != 0)
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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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git_SHA1_Init(&old_sha1_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_sha1)
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git_SHA1_Final(partial_pack_sha1, &old_sha1_ctx);
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git_SHA1_Final(new_pack_sha1, &new_sha1_ctx);
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write_or_die(pack_fd, new_pack_sha1, 20);
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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[46];
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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, 46) == 46 && packname[45] == '\n' &&
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memcmp(packname, "keep\t", 5) == 0) {
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char path[PATH_MAX];
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packname[45] = 0;
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snprintf(path, sizeof(path), "%s/pack/pack-%s.keep",
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get_object_directory(), packname + 5);
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return xstrdup(path);
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}
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return NULL;
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}
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