Merge commit from fork

Before this change, if writing to a local backend with --metadata and
--links, if the incoming metadata contained mode or ownership
information then rclone would apply the mode/ownership to the
destination of the link not the link itself.

This fixes the problem by using the link safe sycall variants
lchown/fchmodat when --links and --metadata is in use. Note that Linux
does not support setting permissions on symlinks, so rclone emits a
debug message in this case.

This also fixes setting times on symlinks on Windows which wasn't
implemented for atime, mtime and was incorrectly setting the target of
the symlink for btime.

See: https://github.com/rclone/rclone/security/advisories/GHSA-hrxh-9w67-g4cv

backend/local/local_internal_test.go

@@ -268,22 +268,66 @@ func TestMetadata(t *testing.T) {
 	r := fstest.NewRun(t)
 	const filePath = "metafile.txt"
 	when := time.Now()
-	const dayLength = len("2001-01-01")
-	whenRFC := when.Format(time.RFC3339Nano)
 	r.WriteFile(filePath, "metadata file contents", when)
 	f := r.Flocal.(*Fs)
 
+	// Set fs into "-l" / "--links" mode
+	f.opt.TranslateSymlinks = true
+
+	// Write a symlink to the file
+	symlinkPath := "metafile-link.txt"
+	osSymlinkPath := filepath.Join(f.root, symlinkPath)
+	symlinkPath += linkSuffix
+	require.NoError(t, os.Symlink(filePath, osSymlinkPath))
+	symlinkModTime := fstest.Time("2002-02-03T04:05:10.123123123Z")
+	require.NoError(t, lChtimes(osSymlinkPath, symlinkModTime, symlinkModTime))
+
 	// Get the object
 	obj, err := f.NewObject(ctx, filePath)
 	require.NoError(t, err)
 	o := obj.(*Object)
 
+	// Get the symlink object
+	symlinkObj, err := f.NewObject(ctx, symlinkPath)
+	require.NoError(t, err)
+	symlinkO := symlinkObj.(*Object)
+
+	// Record metadata for o
+	oMeta, err := o.Metadata(ctx)
+	require.NoError(t, err)
+
+	// Test symlink first to check it doesn't mess up file
+	t.Run("Symlink", func(t *testing.T) {
+		testMetadata(t, r, symlinkO, symlinkModTime)
+	})
+
+	// Read it again
+	oMetaNew, err := o.Metadata(ctx)
+	require.NoError(t, err)
+
+	// Check that operating on the symlink didn't change the file it was pointing to
+	// See: https://github.com/rclone/rclone/security/advisories/GHSA-hrxh-9w67-g4cv
+	assert.Equal(t, oMeta, oMetaNew, "metadata setting on symlink messed up file")
+
+	// Now run the same tests on the file
+	t.Run("File", func(t *testing.T) {
+		testMetadata(t, r, o, when)
+	})
+}
+
+func testMetadata(t *testing.T, r *fstest.Run, o *Object, when time.Time) {
+	ctx := context.Background()
+	whenRFC := when.Format(time.RFC3339Nano)
+	const dayLength = len("2001-01-01")
+
+	f := r.Flocal.(*Fs)
 	features := f.Features()
 
-	var hasXID, hasAtime, hasBtime bool
+	var hasXID, hasAtime, hasBtime, canSetXattrOnLinks bool
 	switch runtime.GOOS {
 	case "darwin", "freebsd", "netbsd", "linux":
 		hasXID, hasAtime, hasBtime = true, true, true
+		canSetXattrOnLinks = runtime.GOOS != "linux"
 	case "openbsd", "solaris":
 		hasXID, hasAtime = true, true
 	case "windows":
@@ -306,6 +350,10 @@ func TestMetadata(t *testing.T) {
 		require.NoError(t, err)
 		assert.Nil(t, m)
 
+		if !canSetXattrOnLinks && o.translatedLink {
+			t.Skip("Skip remainder of test as can't set xattr on symlinks on this OS")
+		}
+
 		inM := fs.Metadata{
 			"potato":  "chips",
 			"cabbage": "soup",
@@ -320,18 +368,21 @@ func TestMetadata(t *testing.T) {
 	})
 
 	checkTime := func(m fs.Metadata, key string, when time.Time) {
+		t.Helper()
 		mt, ok := o.parseMetadataTime(m, key)
 		assert.True(t, ok)
 		dt := mt.Sub(when)
 		precision := time.Second
-		assert.True(t, dt >= -precision && dt <= precision, fmt.Sprintf("%s: dt %v outside +/- precision %v", key, dt, precision))
+		assert.True(t, dt >= -precision && dt <= precision, fmt.Sprintf("%s: dt %v outside +/- precision %v want %v got %v", key, dt, precision, mt, when))
 	}
 
 	checkInt := func(m fs.Metadata, key string, base int) int {
+		t.Helper()
 		value, ok := o.parseMetadataInt(m, key, base)
 		assert.True(t, ok)
 		return value
 	}
+
 	t.Run("Read", func(t *testing.T) {
 		m, err := o.Metadata(ctx)
 		require.NoError(t, err)
@@ -341,13 +392,12 @@ func TestMetadata(t *testing.T) {
 		checkInt(m, "mode", 8)
 		checkTime(m, "mtime", when)
 
-		assert.Equal(t, len(whenRFC), len(m["mtime"]))
 		assert.Equal(t, whenRFC[:dayLength], m["mtime"][:dayLength])
 
-		if hasAtime {
+		if hasAtime && !o.translatedLink { // symlinks generally don't record atime
 			checkTime(m, "atime", when)
 		}
-		if hasBtime {
+		if hasBtime && !o.translatedLink { // symlinks generally don't record btime
 			checkTime(m, "btime", when)
 		}
 		if hasXID {
@@ -371,6 +421,10 @@ func TestMetadata(t *testing.T) {
 			"mode":   "0767",
 			"potato": "wedges",
 		}
+		if !canSetXattrOnLinks && o.translatedLink {
+			// Don't change xattr if not supported on symlinks
+			delete(newM, "potato")
+		}
 		err := o.writeMetadata(newM)
 		require.NoError(t, err)
 
@@ -380,7 +434,11 @@ func TestMetadata(t *testing.T) {
 
 		mode := checkInt(m, "mode", 8)
 		if runtime.GOOS != "windows" {
-			assert.Equal(t, 0767, mode&0777, fmt.Sprintf("mode wrong - expecting 0767 got 0%o", mode&0777))
+			expectedMode := 0767
+			if o.translatedLink && runtime.GOOS == "linux" {
+				expectedMode = 0777 // perms of symlinks always read as 0777 on linux
+			}
+			assert.Equal(t, expectedMode, mode&0777, fmt.Sprintf("mode wrong - expecting 0%o got 0%o", expectedMode, mode&0777))
 		}
 
 		checkTime(m, "mtime", newMtime)
@@ -390,7 +448,7 @@ func TestMetadata(t *testing.T) {
 		if haveSetBTime {
 			checkTime(m, "btime", newBtime)
 		}
-		if xattrSupported {
+		if xattrSupported && (canSetXattrOnLinks || !o.translatedLink) {
 			assert.Equal(t, "wedges", m["potato"])
 		}
 	})