[PATCH v3 08/20] commit-graph: verify required chunks are present

[Derrick Stolee <dstolee@microsoft.com>]

The commit-graph file requires the following three chunks:

* OID Fanout
* OID Lookup
* Commit Data

If any of these are missing, then the 'verify' subcommand should
report a failure. This includes the chunk IDs malformed or the
chunk count is truncated.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
---
 commit-graph.c          |  9 +++++++++
 t/t5318-commit-graph.sh | 29 +++++++++++++++++++++++++++++
 2 files changed, 38 insertions(+)

diff --git a/commit-graph.c b/commit-graph.c
index 55b41664ee..06e3e4f9ba 100644
--- a/commit-graph.c
+++ b/commit-graph.c
@@ -860,5 +860,14 @@ int verify_commit_graph(struct commit_graph *g)
 		return 1;
 	}
 
+	verify_commit_graph_error = 0;
+
+	if (!g->chunk_oid_fanout)
+		graph_report("commit-graph is missing the OID Fanout chunk");
+	if (!g->chunk_oid_lookup)
+		graph_report("commit-graph is missing the OID Lookup chunk");
+	if (!g->chunk_commit_data)
+		graph_report("commit-graph is missing the Commit Data chunk");
+
 	return verify_commit_graph_error;
 }
diff --git a/t/t5318-commit-graph.sh b/t/t5318-commit-graph.sh
index bd64481c7a..4ef3fe3dc2 100755
--- a/t/t5318-commit-graph.sh
+++ b/t/t5318-commit-graph.sh
@@ -249,6 +249,15 @@ test_expect_success 'git commit-graph verify' '
 
 GRAPH_BYTE_VERSION=4
 GRAPH_BYTE_HASH=5
+GRAPH_BYTE_CHUNK_COUNT=6
+GRAPH_CHUNK_LOOKUP_OFFSET=8
+GRAPH_CHUNK_LOOKUP_WIDTH=12
+GRAPH_CHUNK_LOOKUP_ROWS=5
+GRAPH_BYTE_OID_FANOUT_ID=$GRAPH_CHUNK_LOOKUP_OFFSET
+GRAPH_BYTE_OID_LOOKUP_ID=`expr $GRAPH_CHUNK_LOOKUP_OFFSET + \
+			      1 \* $GRAPH_CHUNK_LOOKUP_WIDTH`
+GRAPH_BYTE_COMMIT_DATA_ID=`expr $GRAPH_CHUNK_LOOKUP_OFFSET + \
+				2 \* $GRAPH_CHUNK_LOOKUP_WIDTH`
 
 # usage: corrupt_graph_and_verify <position> <data> <string>
 # Manipulates the commit-graph file at the position
@@ -283,4 +292,24 @@ test_expect_success 'detect bad hash version' '
 		"hash version"
 '
 
+test_expect_success 'detect bad chunk count' '
+	corrupt_graph_and_verify $GRAPH_BYTE_CHUNK_COUNT "\02" \
+		"missing the Commit Data chunk"
+'
+
+test_expect_success 'detect missing OID fanout chunk' '
+	corrupt_graph_and_verify $GRAPH_BYTE_OID_FANOUT_ID "\0" \
+		"missing the OID Fanout chunk"
+'
+
+test_expect_success 'detect missing OID lookup chunk' '
+	corrupt_graph_and_verify $GRAPH_BYTE_OID_LOOKUP_ID "\0" \
+		"missing the OID Lookup chunk"
+'
+
+test_expect_success 'detect missing commit data chunk' '
+	corrupt_graph_and_verify $GRAPH_BYTE_COMMIT_DATA_ID "\0" \
+		"missing the Commit Data chunk"
+'
+
 test_done
-- 
2.16.2.329.gfb62395de6