On Mon, Oct 28, 2019 at 01:01:49PM +0100, Johannes Schindelin wrote:

quoted

quoted

@@ -349,10 +349,16 @@ static int check_common(const char *unmatched, void *value, void *baton)
 static void update_common_dir(struct strbuf *buf, int git_dir_len,
 			      const char *common_dir)
 {
-	char *base = buf->buf + git_dir_len;
+	char *base = buf->buf + git_dir_len, *base2 = NULL;
+
+	if (ends_with(base, ".lock"))
+		base = base2 = xstrndup(base, strlen(base) - 5);

Hm, this adds the magic number 5 and calls strlen(base) twice, because
ends_with() calls strip_suffix(), which calls strlen().  Calling
strip_suffix() directly would allow us to avoid the magic number and
the second strlen():

  size_t len;
  if (strip_suffix(base, ".lock", &len))
          base = base2 = xstrndup(base, len);

Actually, we should probably avoid the extra allocation. Earlier, I was
concerned about multi-threading issues when attempting to modify the
`strbuf`. But then, we modify that `strbuf` a couple of lines later
anyway,

Do we?  You're right, we do indeed, because in replace_dir(buf, ...)
we call strbuf_splice(buf, ...).
OK, then your suggestion below is even better.

so my fears were totally unfounded. Therefore, my current
version reads like this:

-- snip --
	int has_lock_suffix = strbuf_strip_suffix(buf, LOCK_SUFFIX);

	init_common_trie();
	if (trie_find(&common_trie, base, check_common, NULL) > 0)
		replace_dir(buf, git_dir_len, common_dir);

	if (has_lock_suffix)
		strbuf_addstr(buf, LOCK_SUFFIX);
-- snap --