1 files changed, 40 insertions, 0 deletions
diff --git a/builtin/get-tar-commit-id.c b/builtin/get-tar-commit-id.c
new file mode 100644
index 0000000000..aa72596083
--- /dev/null
+++ b/builtin/get-tar-commit-id.c
@@ -0,0 +1,40 @@
+/*
+ * Copyright (c) 2005, 2006 Rene Scharfe
+ */
+#include "cache.h"
+#include "commit.h"
+#include "tar.h"
+#include "builtin.h"
+#include "quote.h"
+
+static const char builtin_get_tar_commit_id_usage[] =
+"git get-tar-commit-id < <tarfile>";
+
+/* ustar header + extended global header content */
+#define RECORDSIZE	(512)
+#define HEADERSIZE (2 * RECORDSIZE)
+
+int cmd_get_tar_commit_id(int argc, const char **argv, const char *prefix)
+{
+	char buffer[HEADERSIZE];
+	struct ustar_header *header = (struct ustar_header *)buffer;
+	char *content = buffer + RECORDSIZE;
+	ssize_t n;
+
+	if (argc != 1)
+		usage(builtin_get_tar_commit_id_usage);
+
+	n = read_in_full(0, buffer, HEADERSIZE);
+	if (n < HEADERSIZE)
+		die("git get-tar-commit-id: read error");
+	if (header->typeflag[0] != 'g')
+		return 1;
+	if (memcmp(content, "52 comment=", 11))
+		return 1;
+
+	n = write_in_full(1, content + 11, 41);
+	if (n < 41)
+		die_errno("git get-tar-commit-id: write error");
+
+	return 0;
+}