multi-pack-index: load into memory

Create a new multi_pack_index struct for loading multi-pack-indexes into
memory. Create a test-tool builtin for reading basic information about
that multi-pack-index to verify the correct data is written.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

3 files changed, 33 insertions, 0 deletions

diff --git a/t/helper/test-read-midx.c b/t/helper/test-read-midx.c
new file mode 100644
index 0000000000..988a487169
--- /dev/null
+++ b/t/helper/test-read-midx.c
@@ -0,0 +1,31 @@
+#include "test-tool.h"
+#include "cache.h"
+#include "midx.h"
+#include "repository.h"
+#include "object-store.h"
+
+static int read_midx_file(const char *object_dir)
+{
+	struct multi_pack_index *m = load_multi_pack_index(object_dir);
+
+	if (!m)
+		return 1;
+
+	printf("header: %08x %d %d %d\n",
+	       m->signature,
+	       m->version,
+	       m->num_chunks,
+	       m->num_packs);
+
+	printf("object-dir: %s\n", m->object_dir);
+
+	return 0;
+}
+
+int cmd__read_midx(int argc, const char **argv)
+{
+	if (argc != 2)
+		usage("read-midx <object-dir>");
+
+	return read_midx_file(argv[1]);
+}
diff --git a/t/helper/test-tool.c b/t/helper/test-tool.c
index 805a45de9c..1c3ab36e6c 100644
--- a/t/helper/test-tool.c
+++ b/t/helper/test-tool.c
@@ -27,6 +27,7 @@ static struct test_cmd cmds[] = {
 	{ "path-utils", cmd__path_utils },
 	{ "prio-queue", cmd__prio_queue },
 	{ "read-cache", cmd__read_cache },
+	{ "read-midx", cmd__read_midx },
 	{ "ref-store", cmd__ref_store },
 	{ "regex", cmd__regex },
 	{ "revision-walking", cmd__revision_walking },
diff --git a/t/helper/test-tool.h b/t/helper/test-tool.h
index 7116ddfb94..6af8c08a66 100644
--- a/t/helper/test-tool.h
+++ b/t/helper/test-tool.h
@@ -21,6 +21,7 @@ int cmd__online_cpus(int argc, const char **argv);
 int cmd__path_utils(int argc, const char **argv);
 int cmd__prio_queue(int argc, const char **argv);
 int cmd__read_cache(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);
 int cmd__revision_walking(int argc, const char **argv);