Teach git apply to respect core.fileMode settings

CC: Johannes Schindelin <johannes.schindelin@gmail.com>
Signed-off-by: Chandra Pratap <chandrapratap3519@gmail.com>

apply.c

@@ -3778,8 +3778,11 @@ static int check_preimage(struct apply_state *state,
 		return error_errno("%s", old_name);
 	}
 
-	if (!state->cached && !previous)
-		st_mode = ce_mode_from_stat(*ce, st->st_mode);
+	if (!state->cached && !previous) {
+		if (!trust_executable_bit && patch->old_mode)
+			st_mode = patch->old_mode;
+		else st_mode = ce_mode_from_stat(*ce, st->st_mode);
+	}
 
 	if (patch->is_new < 0)
 		patch->is_new = 0;

t/t4129-apply-samemode.sh

@@ -101,4 +101,19 @@ test_expect_success POSIXPERM 'do not use core.sharedRepository for working tree
 	)
 '
 
+test_expect_success FILEMODE 'ensure git apply respects core.fileMode' '
+	test_config core.fileMode false &&
+	echo true >script.sh &&
+	git add --chmod=+x script.sh &&
+	test_tick && git commit -m "Add script" &&
+
+	echo true >>script.sh &&
+	test_tick && git commit -m "Modify script" script.sh &&
+	git format-patch -1 --stdout >patch &&
+
+	git switch -c branch HEAD^ &&
+	git apply patch 2>err &&
+	! test_grep "has type 100644, expected 100755" err
+'
+
 test_done