1 files changed, 79 insertions, 0 deletions
diff --git a/builtin/diff-index.c b/builtin/diff-index.c
new file mode 100644
index 0000000..220f341
--- /dev/null
+++ b/builtin/diff-index.c
@@ -0,0 +1,79 @@
+#include "builtin.h"
+#include "config.h"
+#include "diff.h"
+#include "diff-merges.h"
+#include "commit.h"
+#include "preload-index.h"
+#include "repository.h"
+#include "revision.h"
+#include "setup.h"
+#include "sparse-index.h"
+#include "submodule.h"
+
+static const char diff_cache_usage[] =
+"git diff-index [-m] [--cached] [--merge-base] "
+"[<common-diff-options>] <tree-ish> [<path>...]"
+"\n"
+COMMON_DIFF_OPTIONS_HELP;
+
+int cmd_diff_index(int argc, const char **argv, const char *prefix)
+{
+	struct rev_info rev;
+	unsigned int option = 0;
+	int i;
+	int result;
+
+	if (argc == 2 && !strcmp(argv[1], "-h"))
+		usage(diff_cache_usage);
+
+	git_config(git_diff_basic_config, NULL); /* no "diff" UI options */
+	repo_init_revisions(the_repository, &rev, prefix);
+	rev.abbrev = 0;
+	prefix = precompose_argv_prefix(argc, argv, prefix);
+
+	/*
+	 * We need (some of) diff for merges options (e.g., --cc), and we need
+	 * to avoid conflict with our own meaning of "-m".
+	 */
+	diff_merges_suppress_m_parsing();
+
+	argc = setup_revisions(argc, argv, &rev, NULL);
+	for (i = 1; i < argc; i++) {
+		const char *arg = argv[i];
+
+		if (!strcmp(arg, "--cached"))
+			option |= DIFF_INDEX_CACHED;
+		else if (!strcmp(arg, "--merge-base"))
+			option |= DIFF_INDEX_MERGE_BASE;
+		else if (!strcmp(arg, "-m"))
+			rev.match_missing = 1;
+		else
+			usage(diff_cache_usage);
+	}
+	if (!rev.diffopt.output_format)
+		rev.diffopt.output_format = DIFF_FORMAT_RAW;
+
+	rev.diffopt.rotate_to_strict = 1;
+
+	/*
+	 * Make sure there is one revision (i.e. pending object),
+	 * and there is no revision filtering parameters.
+	 */
+	if (rev.pending.nr != 1 ||
+	    rev.max_count != -1 || rev.min_age != -1 || rev.max_age != -1)
+		usage(diff_cache_usage);
+	if (!(option & DIFF_INDEX_CACHED)) {
+		setup_work_tree();
+		if (repo_read_index_preload(the_repository, &rev.diffopt.pathspec, 0) < 0) {
+			perror("repo_read_index_preload");
+			return -1;
+		}
+	} else if (repo_read_index(the_repository) < 0) {
+		perror("repo_read_index");
+		return -1;
+	}
+	run_diff_index(&rev, option);
+	result = diff_result_code(&rev.diffopt);
+	release_revisions(&rev);
+	return result;
+}