Add option to panic gofer if writes are attempted over RO mounts

This is used when '--overlay=true' to guarantee writes are not sent to gofer.

PiperOrigin-RevId: 210116288
Change-Id: I7616008c4c0e8d3668e07a205207f46e2144bf30

1 files changed, 25 insertions, 0 deletions

diff --git a/runsc/fsgofer/fsgofer_test.go b/runsc/fsgofer/fsgofer_test.go
index 8d038eaf6..fcece4e83 100644
--- a/runsc/fsgofer/fsgofer_test.go
+++ b/runsc/fsgofer/fsgofer_test.go
@@ -34,6 +34,15 @@ func init() {
 	allConfs = append(allConfs, roConfs...)
 }
 
+func assertPanic(t *testing.T, f func()) {
+	defer func() {
+		if r := recover(); r == nil {
+			t.Errorf("function did not panic")
+		}
+	}()
+	f()
+}
+
 var (
 	allTypes = []fileType{regular, directory, symlink}
 
@@ -434,6 +443,22 @@ func TestROMountChecks(t *testing.T) {
 	})
 }
 
+func TestROMountPanics(t *testing.T) {
+	conf := Config{ROMount: true, PanicOnWrite: true}
+	runCustom(t, allTypes, []Config{conf}, func(t *testing.T, s state) {
+		assertPanic(t, func() { s.file.Create("..", p9.ReadWrite, 0777, p9.UID(os.Getuid()), p9.GID(os.Getgid())) })
+		assertPanic(t, func() { s.file.Mkdir("..", 0777, p9.UID(os.Getuid()), p9.GID(os.Getgid())) })
+		assertPanic(t, func() { s.file.Rename(s.file, "..") })
+		assertPanic(t, func() { s.file.Symlink("some_place", "..", p9.UID(os.Getuid()), p9.GID(os.Getgid())) })
+		assertPanic(t, func() { s.file.UnlinkAt("..", 0) })
+		assertPanic(t, func() { s.file.Link(s.file, "..") })
+
+		valid := p9.SetAttrMask{Size: true}
+		attr := p9.SetAttr{Size: 0}
+		assertPanic(t, func() { s.file.SetAttr(valid, attr) })
+	})
+}
+
 func TestInvalidName(t *testing.T) {
 	runCustom(t, []fileType{regular}, rwConfs, func(t *testing.T, s state) {
 		if _, _, _, _, err := s.file.Create("..", p9.ReadWrite, 0777, p9.UID(os.Getuid()), p9.GID(os.Getgid())); err != syscall.EINVAL {