git apply --directory broken for new files

We carefully verify that the input to git-apply is sane,
including cross-checking that the filenames we see in "+++"
headers match what was provided on the command line of "diff
--git". When --directory is used, however, we ended up
comparing the unadorned name to one with the prepended root,
causing us to complain about a mismatch.

We simply need to prepend the root directory, if any, when
pulling the name out of the git header.

Signed-off-by: Jeff King <peff@peff.net>
Acked-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

builtin-apply.c

@@ -810,6 +810,13 @@ static int parse_git_header(char *line, int len, unsigned int size, struct patch
 	 * the default name from the header.
 	 */
 	patch->def_name = git_header_name(line, len);
+	if (patch->def_name && root) {
+		char *s = xmalloc(root_len + strlen(patch->def_name) + 1);
+		strcpy(s, root);
+		strcpy(s + root_len, patch->def_name);
+		free(patch->def_name);
+		patch->def_name = s;
+	}
 
 	line += len;
 	size -= len;

t/t4128-apply-root.sh

@@ -40,4 +40,56 @@ test_expect_success 'apply --directory -p (2) ' '
 
 '
 
+cat > patch << EOF
+diff --git a/newfile b/newfile
+new file mode 100644
+index 0000000..d95f3ad
+--- /dev/null
++++ b/newfile
+@@ -0,0 +1 @@
++content
+EOF
+
+test_expect_success 'apply --directory (new file)' '
+	git reset --hard initial &&
+	git apply --directory=some/sub/dir/ --index patch &&
+	test content = $(git show :some/sub/dir/newfile) &&
+	test content = $(cat some/sub/dir/newfile)
+'
+
+cat > patch << EOF
+diff --git a/delfile b/delfile
+deleted file mode 100644
+index d95f3ad..0000000
+--- a/delfile
++++ /dev/null
+@@ -1 +0,0 @@
+-content
+EOF
+
+test_expect_success 'apply --directory (delete file)' '
+	git reset --hard initial &&
+	echo content >some/sub/dir/delfile &&
+	git add some/sub/dir/delfile &&
+	git apply --directory=some/sub/dir/ --index patch &&
+	! git ls-files | grep delfile
+'
+
+cat > patch << 'EOF'
+diff --git "a/qu\157tefile" "b/qu\157tefile"
+new file mode 100644
+index 0000000..d95f3ad
+--- /dev/null
++++ "b/qu\157tefile"
+@@ -0,0 +1 @@
++content
+EOF
+
+test_expect_success 'apply --directory (quoted filename)' '
+	git reset --hard initial &&
+	git apply --directory=some/sub/dir/ --index patch &&
+	test content = $(git show :some/sub/dir/quotefile) &&
+	test content = $(cat some/sub/dir/quotefile)
+'
+
 test_done