3 files changed, 55 insertions, 0 deletions
diff --git a/t/helper/test-read-graph.c b/t/helper/test-read-graph.c
new file mode 100644
index 0000000000..d2884efe0a
--- /dev/null
+++ b/t/helper/test-read-graph.c
@@ -0,0 +1,53 @@
+#include "test-tool.h"
+#include "cache.h"
+#include "commit-graph.h"
+#include "repository.h"
+#include "object-store.h"
+
+int cmd__read_graph(int argc, const char **argv)
+{
+	struct commit_graph *graph = NULL;
+	char *graph_name;
+	int open_ok;
+	int fd;
+	struct stat st;
+	const char *object_dir;
+
+	setup_git_directory();
+	object_dir = get_object_directory();
+
+	graph_name = get_commit_graph_filename(object_dir);
+
+	open_ok = open_commit_graph(graph_name, &fd, &st);
+	if (!open_ok)
+		die_errno(_("Could not open commit-graph '%s'"), graph_name);
+
+	graph = load_commit_graph_one_fd_st(fd, &st);
+	if (!graph)
+		return 1;
+
+	FREE_AND_NULL(graph_name);
+
+	printf("header: %08x %d %d %d %d\n",
+		ntohl(*(uint32_t*)graph->data),
+		*(unsigned char*)(graph->data + 4),
+		*(unsigned char*)(graph->data + 5),
+		*(unsigned char*)(graph->data + 6),
+		*(unsigned char*)(graph->data + 7));
+	printf("num_commits: %u\n", graph->num_commits);
+	printf("chunks:");
+
+	if (graph->chunk_oid_fanout)
+		printf(" oid_fanout");
+	if (graph->chunk_oid_lookup)
+		printf(" oid_lookup");
+	if (graph->chunk_commit_data)
+		printf(" commit_metadata");
+	if (graph->chunk_extra_edges)
+		printf(" extra_edges");
+	printf("\n");
+
+	UNLEAK(graph);
+
+	return 0;
+}
diff --git a/t/helper/test-tool.c b/t/helper/test-tool.c
index 19ee26d931..f20989d449 100644
--- a/t/helper/test-tool.c
+++ b/t/helper/test-tool.c
@@ -45,6 +45,7 @@ static struct test_cmd cmds[] = {
 	{ "progress", cmd__progress },
 	{ "reach", cmd__reach },
 	{ "read-cache", cmd__read_cache },
+	{ "read-graph", cmd__read_graph },
 	{ "read-midx", cmd__read_midx },
 	{ "ref-store", cmd__ref_store },
 	{ "regex", cmd__regex },
diff --git a/t/helper/test-tool.h b/t/helper/test-tool.h
index c2aa56ef50..8ed2af71d1 100644
--- a/t/helper/test-tool.h
+++ b/t/helper/test-tool.h
@@ -35,6 +35,7 @@ int cmd__prio_queue(int argc, const char **argv);
 int cmd__progress(int argc, const char **argv);
 int cmd__reach(int argc, const char **argv);
 int cmd__read_cache(int argc, const char **argv);
+int cmd__read_graph(int argc, const char **argv);
 int cmd__read_midx(int argc, const char **argv);
 int cmd__ref_store(int argc, const char **argv);
 int cmd__regex(int argc, const char **argv);