git_snpath(): retire and replace with strbuf_git_path()

In the previous patch, git_snpath() is modified to allocate a new
strbuf buffer because vsnpath() needs that. But that makes it
awkward because git_snpath() receives a pre-allocated buffer from
outside and has to copy data back. Rename it to strbuf_git_path()
and make it receive strbuf directly.

Using git_path() in update_refs_for_switch() which used to call
git_snpath() is safe because that function and all of its callers do
not keep any pointer to the round-robin buffer pool allocated by
get_pathname().

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

path.c

@@ -70,19 +70,12 @@ static void vsnpath(struct strbuf *buf, const char *fmt, va_list args)
 	strbuf_cleanup_path(buf);
 }
 
-char *git_snpath(char *buf, size_t n, const char *fmt, ...)
+void strbuf_git_path(struct strbuf *sb, const char *fmt, ...)
 {
-	struct strbuf sb = STRBUF_INIT;
 	va_list args;
 	va_start(args, fmt);
-	vsnpath(&sb, fmt, args);
+	vsnpath(sb, fmt, args);
 	va_end(args);
-	if (sb.len >= n)
-		strlcpy(buf, bad_path, n);
-	else
-		memcpy(buf, sb.buf, sb.len + 1);
-	strbuf_release(&sb);
-	return buf;
 }
 
 char *git_pathdup(const char *fmt, ...)