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![Petr Baudis](/assets/img/avatar_default.png)
A comment on top of create_tmpfile() describes caveats ('can have problems on various systems (FAT, NFS, Coda)') that should apply in this situation as well. This in the end did not end up solving any of my personal problems, but it might be a useful cleanup patch nevertheless. Signed-off-by: Petr Baudis <pasky@suse.cz> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>
258 lines
7.4 KiB
C
258 lines
7.4 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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char *write_idx_file(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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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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snprintf(tmpfile, sizeof(tmpfile),
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"%s/pack/tmp_idx_XXXXXX", get_object_directory());
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fd = xmkstemp(tmpfile);
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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("unable to create %s: %s", index_name, strerror(errno));
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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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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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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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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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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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SHA1_Init(&old_sha1_ctx);
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SHA1_Init(&new_sha1_ctx);
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if (lseek(pack_fd, 0, SEEK_SET) != 0)
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die("Failed seeking to start of %s: %s", pack_name, strerror(errno));
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if (read_in_full(pack_fd, &hdr, sizeof(hdr)) != sizeof(hdr))
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die("Unable to reread header of %s: %s", pack_name, strerror(errno));
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if (lseek(pack_fd, 0, SEEK_SET) != 0)
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die("Failed seeking to start of %s: %s", pack_name, strerror(errno));
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SHA1_Update(&old_sha1_ctx, &hdr, sizeof(hdr));
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hdr.hdr_entries = htonl(object_count);
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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("Failed to checksum %s: %s", pack_name, strerror(errno));
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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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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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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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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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SHA1_Final(partial_pack_sha1, &old_sha1_ctx);
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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 expects 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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