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4d80560c54
Create a new multi_pack_index struct for loading multi-pack-indexes into memory. Create a test-tool builtin for reading basic information about that multi-pack-index to verify the correct data is written. Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
137 lines
3.2 KiB
C
137 lines
3.2 KiB
C
#include "cache.h"
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#include "csum-file.h"
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#include "lockfile.h"
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#include "object-store.h"
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#include "midx.h"
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#define MIDX_SIGNATURE 0x4d494458 /* "MIDX" */
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#define MIDX_VERSION 1
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#define MIDX_BYTE_FILE_VERSION 4
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#define MIDX_BYTE_HASH_VERSION 5
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#define MIDX_BYTE_NUM_CHUNKS 6
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#define MIDX_BYTE_NUM_PACKS 8
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#define MIDX_HASH_VERSION 1
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#define MIDX_HEADER_SIZE 12
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#define MIDX_HASH_LEN 20
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#define MIDX_MIN_SIZE (MIDX_HEADER_SIZE + MIDX_HASH_LEN)
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static char *get_midx_filename(const char *object_dir)
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{
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return xstrfmt("%s/pack/multi-pack-index", object_dir);
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}
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struct multi_pack_index *load_multi_pack_index(const char *object_dir)
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{
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struct multi_pack_index *m = NULL;
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int fd;
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struct stat st;
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size_t midx_size;
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void *midx_map = NULL;
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uint32_t hash_version;
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char *midx_name = get_midx_filename(object_dir);
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fd = git_open(midx_name);
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if (fd < 0)
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goto cleanup_fail;
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if (fstat(fd, &st)) {
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error_errno(_("failed to read %s"), midx_name);
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goto cleanup_fail;
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}
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midx_size = xsize_t(st.st_size);
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if (midx_size < MIDX_MIN_SIZE) {
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error(_("multi-pack-index file %s is too small"), midx_name);
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goto cleanup_fail;
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}
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FREE_AND_NULL(midx_name);
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midx_map = xmmap(NULL, midx_size, PROT_READ, MAP_PRIVATE, fd, 0);
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FLEX_ALLOC_MEM(m, object_dir, object_dir, strlen(object_dir));
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m->fd = fd;
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m->data = midx_map;
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m->data_len = midx_size;
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m->signature = get_be32(m->data);
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if (m->signature != MIDX_SIGNATURE) {
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error(_("multi-pack-index signature 0x%08x does not match signature 0x%08x"),
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m->signature, MIDX_SIGNATURE);
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goto cleanup_fail;
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}
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m->version = m->data[MIDX_BYTE_FILE_VERSION];
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if (m->version != MIDX_VERSION) {
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error(_("multi-pack-index version %d not recognized"),
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m->version);
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goto cleanup_fail;
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}
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hash_version = m->data[MIDX_BYTE_HASH_VERSION];
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if (hash_version != MIDX_HASH_VERSION) {
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error(_("hash version %u does not match"), hash_version);
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goto cleanup_fail;
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}
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m->hash_len = MIDX_HASH_LEN;
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m->num_chunks = m->data[MIDX_BYTE_NUM_CHUNKS];
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m->num_packs = get_be32(m->data + MIDX_BYTE_NUM_PACKS);
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return m;
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cleanup_fail:
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free(m);
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free(midx_name);
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if (midx_map)
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munmap(midx_map, midx_size);
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if (0 <= fd)
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close(fd);
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return NULL;
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}
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static size_t write_midx_header(struct hashfile *f,
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unsigned char num_chunks,
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uint32_t num_packs)
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{
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unsigned char byte_values[4];
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hashwrite_be32(f, MIDX_SIGNATURE);
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byte_values[0] = MIDX_VERSION;
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byte_values[1] = MIDX_HASH_VERSION;
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byte_values[2] = num_chunks;
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byte_values[3] = 0; /* unused */
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hashwrite(f, byte_values, sizeof(byte_values));
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hashwrite_be32(f, num_packs);
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return MIDX_HEADER_SIZE;
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}
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int write_midx_file(const char *object_dir)
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{
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unsigned char num_chunks = 0;
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char *midx_name;
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struct hashfile *f = NULL;
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struct lock_file lk;
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midx_name = get_midx_filename(object_dir);
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if (safe_create_leading_directories(midx_name)) {
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UNLEAK(midx_name);
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die_errno(_("unable to create leading directories of %s"),
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midx_name);
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}
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hold_lock_file_for_update(&lk, midx_name, LOCK_DIE_ON_ERROR);
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f = hashfd(lk.tempfile->fd, lk.tempfile->filename.buf);
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FREE_AND_NULL(midx_name);
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write_midx_header(f, num_chunks, 0);
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finalize_hashfile(f, NULL, CSUM_FSYNC | CSUM_HASH_IN_STREAM);
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commit_lock_file(&lk);
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return 0;
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}
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