[PATCH v2 02/12] commit-graph: verify file header information

[Derrick Stolee]

During a run of 'git commit-graph verify', list the issues with the
header information in the commit-graph file. Some of this information
is inferred from the loaded 'struct commit_graph'. Some header
information is checked as part of load_commit_graph_one().

Signed-off-by: Derrick Stolee <dsto...@microsoft.com>
---
 commit-graph.c | 32 +++++++++++++++++++++++++++++++-
 1 file changed, 31 insertions(+), 1 deletion(-)

diff --git a/commit-graph.c b/commit-graph.c
index b25aaed128..d2db20e49a 100644
--- a/commit-graph.c
+++ b/commit-graph.c
@@ -818,7 +818,37 @@ void write_commit_graph(const char *obj_dir,
        oids.nr = 0;
 }
 
+static int verify_commit_graph_error;
+
+static void graph_report(const char *fmt, ...)
+{
+       va_list ap;
+       struct strbuf sb = STRBUF_INIT;
+       verify_commit_graph_error = 1;
+
+       va_start(ap, fmt);
+       strbuf_vaddf(&sb, fmt, ap);
+
+       fprintf(stderr, "%s\n", sb.buf);
+       strbuf_release(&sb);
+       va_end(ap);
+}
+
 int verify_commit_graph(struct commit_graph *g)
 {
-       return !g;
+       if (!g) {
+               graph_report("no commit-graph file loaded");
+               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;
 }
-- 
2.16.2.329.gfb62395de6