Hash :
3fd57a75
Author :
Date :
2021-01-04T18:22:43
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/*
* Copyright (C) the libgit2 contributors. All rights reserved.
*
* This file is part of libgit2, distributed under the GNU GPL v2 with
* a Linking Exception. For full terms see the included COPYING file.
*/
#include "commit_graph.h"
#include "futils.h"
#include "hash.h"
#define GIT_COMMIT_GRAPH_MISSING_PARENT 0x70000000
#define COMMIT_GRAPH_SIGNATURE 0x43475048 /* "CGPH" */
#define COMMIT_GRAPH_VERSION 1
#define COMMIT_GRAPH_OBJECT_ID_VERSION 1
struct git_commit_graph_header {
uint32_t signature;
uint8_t version;
uint8_t object_id_version;
uint8_t chunks;
uint8_t base_graph_files;
};
#define COMMIT_GRAPH_OID_FANOUT_ID 0x4f494446 /* "OIDF" */
#define COMMIT_GRAPH_OID_LOOKUP_ID 0x4f49444c /* "OIDL" */
#define COMMIT_GRAPH_COMMIT_DATA_ID 0x43444154 /* "CDAT" */
#define COMMIT_GRAPH_EXTRA_EDGE_LIST_ID 0x45444745 /* "EDGE" */
#define COMMIT_GRAPH_BLOOM_FILTER_INDEX_ID 0x42494458 /* "BIDX" */
#define COMMIT_GRAPH_BLOOM_FILTER_DATA_ID 0x42444154 /* "BDAT" */
struct git_commit_graph_chunk {
off64_t offset;
size_t length;
};
static int commit_graph_error(const char *message)
{
git_error_set(GIT_ERROR_ODB, "invalid commit-graph file - %s", message);
return -1;
}
static int commit_graph_parse_oid_fanout(
git_commit_graph_file *cgraph,
const unsigned char *data,
struct git_commit_graph_chunk *chunk_oid_fanout)
{
uint32_t i, nr;
if (chunk_oid_fanout->offset == 0)
return commit_graph_error("missing OID Fanout chunk");
if (chunk_oid_fanout->length == 0)
return commit_graph_error("empty OID Fanout chunk");
if (chunk_oid_fanout->length != 256 * 4)
return commit_graph_error("OID Fanout chunk has wrong length");
cgraph->oid_fanout = (const uint32_t *)(data + chunk_oid_fanout->offset);
nr = 0;
for (i = 0; i < 256; ++i) {
uint32_t n = ntohl(cgraph->oid_fanout[i]);
if (n < nr)
return commit_graph_error("index is non-monotonic");
nr = n;
}
cgraph->num_commits = nr;
return 0;
}
static int commit_graph_parse_oid_lookup(
git_commit_graph_file *cgraph,
const unsigned char *data,
struct git_commit_graph_chunk *chunk_oid_lookup)
{
uint32_t i;
git_oid *oid, *prev_oid, zero_oid = {{0}};
if (chunk_oid_lookup->offset == 0)
return commit_graph_error("missing OID Lookup chunk");
if (chunk_oid_lookup->length == 0)
return commit_graph_error("empty OID Lookup chunk");
if (chunk_oid_lookup->length != cgraph->num_commits * GIT_OID_RAWSZ)
return commit_graph_error("OID Lookup chunk has wrong length");
cgraph->oid_lookup = oid = (git_oid *)(data + chunk_oid_lookup->offset);
prev_oid = &zero_oid;
for (i = 0; i < cgraph->num_commits; ++i, ++oid) {
if (git_oid_cmp(prev_oid, oid) >= 0)
return commit_graph_error("OID Lookup index is non-monotonic");
prev_oid = oid;
}
return 0;
}
static int commit_graph_parse_commit_data(
git_commit_graph_file *cgraph,
const unsigned char *data,
struct git_commit_graph_chunk *chunk_commit_data)
{
if (chunk_commit_data->offset == 0)
return commit_graph_error("missing Commit Data chunk");
if (chunk_commit_data->length == 0)
return commit_graph_error("empty Commit Data chunk");
if (chunk_commit_data->length != cgraph->num_commits * (GIT_OID_RAWSZ + 16))
return commit_graph_error("Commit Data chunk has wrong length");
cgraph->commit_data = data + chunk_commit_data->offset;
return 0;
}
static int commit_graph_parse_extra_edge_list(
git_commit_graph_file *cgraph,
const unsigned char *data,
struct git_commit_graph_chunk *chunk_extra_edge_list)
{
if (chunk_extra_edge_list->length == 0)
return 0;
if (chunk_extra_edge_list->length % 4 != 0)
return commit_graph_error("malformed Extra Edge List chunk");
cgraph->extra_edge_list = data + chunk_extra_edge_list->offset;
cgraph->num_extra_edge_list = chunk_extra_edge_list->length / 4;
return 0;
}
int git_commit_graph_parse(git_commit_graph_file *cgraph, const unsigned char *data, size_t size)
{
struct git_commit_graph_header *hdr;
const unsigned char *chunk_hdr;
struct git_commit_graph_chunk *last_chunk;
uint32_t i;
off64_t last_chunk_offset, chunk_offset, trailer_offset;
git_oid cgraph_checksum = {{0}};
int error;
struct git_commit_graph_chunk chunk_oid_fanout = {0}, chunk_oid_lookup = {0},
chunk_commit_data = {0}, chunk_extra_edge_list = {0},
chunk_unsupported = {0};
GIT_ASSERT_ARG(cgraph);
if (size < sizeof(struct git_commit_graph_header) + GIT_OID_RAWSZ)
return commit_graph_error("commit-graph is too short");
hdr = ((struct git_commit_graph_header *)data);
if (hdr->signature != htonl(COMMIT_GRAPH_SIGNATURE) || hdr->version != COMMIT_GRAPH_VERSION
|| hdr->object_id_version != COMMIT_GRAPH_OBJECT_ID_VERSION) {
return commit_graph_error("unsupported commit-graph version");
}
if (hdr->chunks == 0)
return commit_graph_error("no chunks in commit-graph");
/*
* The very first chunk's offset should be after the header, all the chunk
* headers, and a special zero chunk.
*/
last_chunk_offset = sizeof(struct git_commit_graph_header) + (1 + hdr->chunks) * 12;
trailer_offset = size - GIT_OID_RAWSZ;
if (trailer_offset < last_chunk_offset)
return commit_graph_error("wrong commit-graph size");
git_oid_cpy(&cgraph->checksum, (git_oid *)(data + trailer_offset));
if (git_hash_buf(&cgraph_checksum, data, (size_t)trailer_offset) < 0)
return commit_graph_error("could not calculate signature");
if (!git_oid_equal(&cgraph_checksum, &cgraph->checksum))
return commit_graph_error("index signature mismatch");
chunk_hdr = data + sizeof(struct git_commit_graph_header);
last_chunk = NULL;
for (i = 0; i < hdr->chunks; ++i, chunk_hdr += 12) {
chunk_offset = ((off64_t)ntohl(*((uint32_t *)(chunk_hdr + 4)))) << 32
| ((off64_t)ntohl(*((uint32_t *)(chunk_hdr + 8))));
if (chunk_offset < last_chunk_offset)
return commit_graph_error("chunks are non-monotonic");
if (chunk_offset >= trailer_offset)
return commit_graph_error("chunks extend beyond the trailer");
if (last_chunk != NULL)
last_chunk->length = (size_t)(chunk_offset - last_chunk_offset);
last_chunk_offset = chunk_offset;
switch (ntohl(*((uint32_t *)(chunk_hdr + 0)))) {
case COMMIT_GRAPH_OID_FANOUT_ID:
chunk_oid_fanout.offset = last_chunk_offset;
last_chunk = &chunk_oid_fanout;
break;
case COMMIT_GRAPH_OID_LOOKUP_ID:
chunk_oid_lookup.offset = last_chunk_offset;
last_chunk = &chunk_oid_lookup;
break;
case COMMIT_GRAPH_COMMIT_DATA_ID:
chunk_commit_data.offset = last_chunk_offset;
last_chunk = &chunk_commit_data;
break;
case COMMIT_GRAPH_EXTRA_EDGE_LIST_ID:
chunk_extra_edge_list.offset = last_chunk_offset;
last_chunk = &chunk_extra_edge_list;
break;
case COMMIT_GRAPH_BLOOM_FILTER_INDEX_ID:
case COMMIT_GRAPH_BLOOM_FILTER_DATA_ID:
chunk_unsupported.offset = last_chunk_offset;
last_chunk = &chunk_unsupported;
break;
default:
return commit_graph_error("unrecognized chunk ID");
}
}
last_chunk->length = (size_t)(trailer_offset - last_chunk_offset);
error = commit_graph_parse_oid_fanout(cgraph, data, &chunk_oid_fanout);
if (error < 0)
return error;
error = commit_graph_parse_oid_lookup(cgraph, data, &chunk_oid_lookup);
if (error < 0)
return error;
error = commit_graph_parse_commit_data(cgraph, data, &chunk_commit_data);
if (error < 0)
return error;
error = commit_graph_parse_extra_edge_list(cgraph, data, &chunk_extra_edge_list);
if (error < 0)
return error;
return 0;
}
int git_commit_graph_open(git_commit_graph_file **cgraph_out, const char *path)
{
git_commit_graph_file *cgraph;
git_file fd = -1;
size_t cgraph_size;
struct stat st;
int error;
/* TODO: properly open the file without access time using O_NOATIME */
fd = git_futils_open_ro(path);
if (fd < 0)
return fd;
if (p_fstat(fd, &st) < 0) {
p_close(fd);
git_error_set(GIT_ERROR_ODB, "multi-pack-index file not found - '%s'", path);
return -1;
}
if (!S_ISREG(st.st_mode) || !git__is_sizet(st.st_size)) {
p_close(fd);
git_error_set(GIT_ERROR_ODB, "invalid pack index '%s'", path);
return -1;
}
cgraph_size = (size_t)st.st_size;
cgraph = git__calloc(1, sizeof(git_commit_graph_file));
GIT_ERROR_CHECK_ALLOC(cgraph);
error = git_buf_sets(&cgraph->filename, path);
if (error < 0)
return error;
error = git_futils_mmap_ro(&cgraph->graph_map, fd, 0, cgraph_size);
p_close(fd);
if (error < 0) {
git_commit_graph_free(cgraph);
return error;
}
if ((error = git_commit_graph_parse(cgraph, cgraph->graph_map.data, cgraph_size)) < 0) {
git_commit_graph_free(cgraph);
return error;
}
*cgraph_out = cgraph;
return 0;
}
int git_commit_graph_close(git_commit_graph_file *cgraph)
{
GIT_ASSERT_ARG(cgraph);
if (cgraph->graph_map.data)
git_futils_mmap_free(&cgraph->graph_map);
return 0;
}
void git_commit_graph_free(git_commit_graph_file *cgraph)
{
if (!cgraph)
return;
git_buf_dispose(&cgraph->filename);
git_commit_graph_close(cgraph);
git__free(cgraph);
}