Built-in git-get-tar-commit-id

[git.git] / builtin-tar-tree.c

diff --git a/builtin-tar-tree.c b/builtin-tar-tree.c
index 7663b9b..58a8ccd 100644 (file)
--- a/builtin-tar-tree.c
+++ b/builtin-tar-tree.c
@@ -402,3 +402,28 @@ int cmd_tar_tree(int argc, const char **argv, char **envp)
                return remote_tar(argc, argv);
        return generate_tar(argc, argv, envp);
 }
+
+/* ustar header + extended global header content */
+#define HEADERSIZE (2 * RECORDSIZE)
+
+int cmd_get_tar_commit_id(int argc, const char **argv, char **envp)
+{
+       char buffer[HEADERSIZE];
+       struct ustar_header *header = (struct ustar_header *)buffer;
+       char *content = buffer + RECORDSIZE;
+       ssize_t n;
+
+       n = xread(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 = xwrite(1, content + 11, 41);
+       if (n < 41)
+               die("git-get-tar-commit-id: write error");
+
+       return 0;
+}