From 0004386f29d1165d5dbd54b26170560a7a98e125 Mon Sep 17 00:00:00 2001
From: Edward Thomson <ethomson@edwardthomson.com>
Date: Wed, 17 Jun 2015 06:03:01 -0700
Subject: [PATCH] apply: handle empty patches

When a patch is empty, simply copy the source into the destination.
---
 src/apply.c            | 5 ++++-
 tests/apply/fromdiff.c | 8 ++++++++
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/src/apply.c b/src/apply.c
index e75fa5b4d..f1bd9f4b5 100644
--- a/src/apply.c
+++ b/src/apply.c
@@ -262,7 +262,10 @@ int git_apply__patch(
 			patch->nfile.file->mode : GIT_FILEMODE_BLOB;
 	}
 
-	if ((error = apply_hunks(contents_out, source, source_len, patch)) < 0)
+	/* If the patch is empty, simply keep the source unchanged */
+	if (patch->hunks.size == 0)
+		git_buf_put(contents_out, source, source_len);
+	else if ((error = apply_hunks(contents_out, source, source_len, patch)) < 0)
 		goto done;
 
 	if (patch->delta->status == GIT_DELTA_DELETED &&
diff --git a/tests/apply/fromdiff.c b/tests/apply/fromdiff.c
index 64ed9de79..af0541de8 100644
--- a/tests/apply/fromdiff.c
+++ b/tests/apply/fromdiff.c
@@ -174,3 +174,11 @@ void test_apply_fromdiff__delete(void)
 		NULL, NULL,
 		PATCH_DELETE_ORIGINAL, NULL));
 }
+
+void test_apply_fromdiff__no_change(void)
+{
+	cl_git_pass(apply_buf(
+		FILE_ORIGINAL, "file.txt",
+		FILE_ORIGINAL, "file.txt",
+		"", NULL));
+}