[PATCH v3 03/16] files-backend: add files_path()

This will be the replacement for both git_path() and git_path_submodule()
in this file. The idea is backend takes a git path and use that,
oblivious of submodule, linked worktrees and such.

This is the middle step towards that. Eventually the "submodule" field
in 'struct files_ref_store' should be replace by "gitdir". And a
compound ref_store is created to combine two files backends together,
one represents the shared refs in $GIT_COMMON_DIR, one per-worktree. At
that point, files_path() becomes a wrapper of strbuf_vaddf().

Signed-off-by: Nguyễn Thái Ngọc Duy <redacted>
---
 refs/files-backend.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/refs/files-backend.c b/refs/files-backend.c
index f0c878b92..abb8a95e0 100644
--- a/refs/files-backend.c
+++ b/refs/files-backend.c

@@ -930,6 +930,24 @@ struct files_ref_store {
 /* Lock used for the main packed-refs file: */
 static struct lock_file packlock;
 
+__attribute__((format (printf, 3, 4)))
+static void files_path(struct files_ref_store *refs, struct strbuf *sb,
+		       const char *fmt, ...)
+{
+	struct strbuf tmp = STRBUF_INIT;
+	va_list vap;
+
+	va_start(vap, fmt);
+	strbuf_vaddf(&tmp, fmt, vap);
+	va_end(vap);
+	if (refs->submodule)
+		strbuf_git_path_submodule(sb, refs->submodule,
+					  "%s", tmp.buf);
+	else
+		strbuf_git_path(sb, "%s", tmp.buf);
+	strbuf_release(&tmp);
+}
+
 /*
  * Increment the reference count of *packed_refs.
  */

-- 
2.11.0.157.gd943d85