1 files changed, 111 insertions, 0 deletions
diff --git a/src/libgit2/midx.h b/src/libgit2/midx.h
new file mode 100644
index 000000000..bcb0d9a0a
--- /dev/null
+++ b/src/libgit2/midx.h
@@ -0,0 +1,111 @@
+/*
+ * Copyright (C) the libgit2 contributors. All rights reserved.
+ *
+ * This file is part of libgit2, distributed under the GNU GPL v2 with
+ * a Linking Exception. For full terms see the included COPYING file.
+ */
+
+#ifndef INCLUDE_midx_h__
+#define INCLUDE_midx_h__
+
+#include "common.h"
+
+#include <ctype.h>
+
+#include "git2/sys/midx.h"
+
+#include "map.h"
+#include "mwindow.h"
+#include "odb.h"
+#include "oid.h"
+
+/*
+ * A multi-pack-index file.
+ *
+ * This file contains a merged index for multiple independent .pack files. This
+ * can help speed up locating objects without requiring a garbage collection
+ * cycle to create a single .pack file.
+ *
+ * Support for this feature was added in git 2.21, and requires the
+ * `core.multiPackIndex` config option to be set.
+ */
+typedef struct git_midx_file {
+	git_map index_map;
+
+	/* The table of Packfile Names. */
+	git_vector packfile_names;
+
+	/* The OID Fanout table. */
+	const uint32_t *oid_fanout;
+	/* The total number of objects in the index. */
+	uint32_t num_objects;
+
+	/* The OID Lookup table. */
+	unsigned char *oid_lookup;
+
+	/* The Object Offsets table. Each entry has two 4-byte fields with the pack index and the offset. */
+	const unsigned char *object_offsets;
+
+	/* The Object Large Offsets table. */
+	const unsigned char *object_large_offsets;
+	/* The number of entries in the Object Large Offsets table. Each entry has an 8-byte with an offset */
+	size_t num_object_large_offsets;
+
+	/* The trailer of the file. Contains the SHA1-checksum of the whole file. */
+	unsigned char checksum[GIT_HASH_SHA1_SIZE];
+
+	/* something like ".git/objects/pack/multi-pack-index". */
+	git_str filename;
+} git_midx_file;
+
+/*
+ * An entry in the multi-pack-index file. Similar in purpose to git_pack_entry.
+ */
+typedef struct git_midx_entry {
+	/* The index within idx->packfile_names where the packfile name can be found. */
+	size_t pack_index;
+	/* The offset within the .pack file where the requested object is found. */
+	off64_t offset;
+	/* The SHA-1 hash of the requested object. */
+	git_oid sha1;
+} git_midx_entry;
+
+/*
+ * A writer for `multi-pack-index` files.
+ */
+struct git_midx_writer {
+	/*
+	 * The path of the directory where the .pack/.idx files are stored. The
+	 * `multi-pack-index` file will be written to the same directory.
+	 */
+	git_str pack_dir;
+
+	/* The list of `git_pack_file`s. */
+	git_vector packs;
+};
+
+int git_midx_open(
+		git_midx_file **idx_out,
+		const char *path);
+bool git_midx_needs_refresh(
+		const git_midx_file *idx,
+		const char *path);
+int git_midx_entry_find(
+		git_midx_entry *e,
+		git_midx_file *idx,
+		const git_oid *short_oid,
+		size_t len);
+int git_midx_foreach_entry(
+		git_midx_file *idx,
+		git_odb_foreach_cb cb,
+		void *data);
+int git_midx_close(git_midx_file *idx);
+void git_midx_free(git_midx_file *idx);
+
+/* This is exposed for use in the fuzzers. */
+int git_midx_parse(
+		git_midx_file *idx,
+		const unsigned char *data,
+		size_t size);
+
+#endif