Cleanup request error handling; properly handle os.ErrNotExist errors (#150)

server/filesystem/errors.go

@@ -18,6 +18,7 @@ const (
 	ErrCodePathResolution ErrorCode = "E_BADPATH"
 	ErrCodeDenylistFile   ErrorCode = "E_DENYLIST"
 	ErrCodeUnknownError   ErrorCode = "E_UNKNOWN"
+	ErrNotExist           ErrorCode = "E_NOTEXIST"
 )
 
 type Error struct {
@@ -68,6 +69,8 @@ func (e *Error) Error() string {
 			r = "<empty>"
 		}
 		return fmt.Sprintf("filesystem: server path [%s] resolves to a location outside the server root: %s", e.path, r)
+	case ErrNotExist:
+		return "filesystem: does not exist"
 	case ErrCodeUnknownError:
 		fallthrough
 	default:

server/filesystem/filesystem.go

@@ -61,25 +61,28 @@ func (fs *Filesystem) Path() string {
 func (fs *Filesystem) File(p string) (*os.File, Stat, error) {
 	cleaned, err := fs.SafePath(p)
 	if err != nil {
-		return nil, Stat{}, err
+		return nil, Stat{}, errors.WithStackIf(err)
 	}
 	st, err := fs.Stat(cleaned)
 	if err != nil {
-		return nil, Stat{}, err
+		if errors.Is(err, os.ErrNotExist) {
+			return nil, Stat{}, newFilesystemError(ErrNotExist, err)
+		}
+		return nil, Stat{}, errors.WithStackIf(err)
 	}
 	if st.IsDir() {
 		return nil, Stat{}, newFilesystemError(ErrCodeIsDirectory, nil)
 	}
 	f, err := os.Open(cleaned)
 	if err != nil {
-		return nil, Stat{}, err
+		return nil, Stat{}, errors.WithStackIf(err)
 	}
 	return f, st, nil
 }
 
-// Acts by creating the given file and path on the disk if it is not present already. If
-// it is present, the file is opened using the defaults which will truncate the contents.
-// The opened file is then returned to the caller.
+// Touch acts by creating the given file and path on the disk if it is not present
+// already. If  it is present, the file is opened using the defaults which will truncate
+// the contents. The opened file is then returned to the caller.
 func (fs *Filesystem) Touch(p string, flag int) (*os.File, error) {
 	cleaned, err := fs.SafePath(p)
 	if err != nil {

server/filesystem/filesystem_test.go

@@ -84,6 +84,35 @@ func (rfs *rootFs) reset() {
 	}
 }
 
+func TestFilesystem_Openfile(t *testing.T) {
+	g := Goblin(t)
+	fs, rfs := NewFs()
+
+	g.Describe("File", func() {
+		g.It("returns custom error when file does not exist", func() {
+			_, _, err := fs.File("foo/bar.txt")
+
+			g.Assert(err).IsNotNil()
+			g.Assert(IsErrorCode(err, ErrNotExist)).IsTrue()
+		})
+
+		g.It("returns file stat information", func() {
+			_ = rfs.CreateServerFile("foo.txt", []byte("hello world"))
+
+			f, st, err := fs.File("foo.txt")
+			g.Assert(err).IsNil()
+
+			g.Assert(st.Name()).Equal("foo.txt")
+			g.Assert(f).IsNotNil()
+			_ = f.Close()
+		})
+
+		g.AfterEach(func() {
+			rfs.reset()
+		})
+	})
+}
+
 func TestFilesystem_Writefile(t *testing.T) {
 	g := Goblin(t)
 	fs, rfs := NewFs()