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commit-graph: add base graphs chunk

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To quickly verify a commit-graph chain is valid on load, we will
read from the new "Base Graphs Chunk" of each file in the chain.
This will prevent accidentally loading incorrect data from manually
editing the commit-graph-chain file or renaming graph-{hash}.graph
files.

The commit_graph struct already had an object_id struct "oid", but
it was never initialized or used. Add a line to read the hash from
the end of the commit-graph file and into the oid member.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Derrick Stolee
2019-06-18 11:14:26 -07:00
committed by Junio C Hamano
parent 5c84b3396c
commit 118bd57002
3 changed files with 32 additions and 2 deletions
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22
commit-graph.c
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@ -22,6 +22,7 @@
#define GRAPH_CHUNKID_OIDLOOKUP 0x4f49444c /* "OIDL" */
#define GRAPH_CHUNKID_DATA 0x43444154 /* "CDAT" */
#define GRAPH_CHUNKID_EXTRAEDGES 0x45444745 /* "EDGE" */
#define GRAPH_CHUNKID_BASE 0x42415345 /* "BASE" */
#define GRAPH_DATA_WIDTH (the_hash_algo->rawsz + 16)
@ -262,6 +263,12 @@ struct commit_graph *parse_commit_graph(void *graph_map, int fd,
else
graph->chunk_extra_edges = data + chunk_offset;
break;
case GRAPH_CHUNKID_BASE:
if (graph->chunk_base_graphs)
chunk_repeated = 1;
else
graph->chunk_base_graphs = data + chunk_offset;
}
if (chunk_repeated) {
@ -280,6 +287,8 @@ struct commit_graph *parse_commit_graph(void *graph_map, int fd,
last_chunk_offset = chunk_offset;
}
hashcpy(graph->oid.hash, graph->data + graph->data_len - graph->hash_len);
if (verify_commit_graph_lite(graph))
return NULL;
@ -315,8 +324,21 @@ static int add_graph_to_chain(struct commit_graph *g,
{
struct commit_graph *cur_g = chain;
if (n && !g->chunk_base_graphs) {
warning(_("commit-graph has no base graphs chunk"));
return 0;
}
while (n) {
n--;
if (!cur_g ||
!oideq(&oids[n], &cur_g->oid) ||
!hasheq(oids[n].hash, g->chunk_base_graphs + g->hash_len * n)) {
warning(_("commit-graph chain does not match"));
return 0;
}
cur_g = cur_g->base_graph;
}