Add Stat to finder/fs

Add a Stat method to finder/fs that will be used by finder to read
the mode of the target of a symlink.

Bug: 157656545
Test: fs_test.go
Change-Id: Ie2b4509b7d11857d9a1685de4477088b91d43c63

3 files changed, 101 insertions, 9 deletions

diff --git a/finder/fs/Android.bp b/finder/fs/Android.bp
index 835eb0b31..b71934fbd 100644
--- a/finder/fs/Android.bp
+++ b/finder/fs/Android.bp
@@ -25,6 +25,7 @@ bootstrap_go_package {
         "test.go",
     ],
     testSrcs: [
+        "fs_test.go",
         "readdir_test.go",
     ],
     darwin: {
diff --git a/finder/fs/fs.go b/finder/fs/fs.go
index 071f7640f..d2e3e4ab0 100644
--- a/finder/fs/fs.go
+++ b/finder/fs/fs.go
@@ -51,6 +51,7 @@ type FileSystem interface {
 	// getting information about files
 	Open(name string) (file io.ReadCloser, err error)
 	Lstat(path string) (stats os.FileInfo, err error)
+	Stat(path string) (stats os.FileInfo, err error)
 	ReadDir(path string) (contents []DirEntryInfo, err error)
 
 	InodeNumber(info os.FileInfo) (number uint64, err error)
@@ -99,6 +100,10 @@ func (osFs) Lstat(path string) (stats os.FileInfo, err error) {
 	return os.Lstat(path)
 }
 
+func (osFs) Stat(path string) (stats os.FileInfo, err error) {
+	return os.Stat(path)
+}
+
 func (osFs) ReadDir(path string) (contents []DirEntryInfo, err error) {
 	entries, err := readdir(path)
 	if err != nil {
@@ -376,7 +381,7 @@ type mockFileInfo struct {
 	size         int64
 	modTime      time.Time // time at which the inode's contents were modified
 	permTime     time.Time // time at which the inode's permissions were modified
-	isDir        bool
+	mode         os.FileMode
 	inodeNumber  uint64
 	deviceNumber uint64
 }
@@ -390,7 +395,7 @@ func (m *mockFileInfo) Size() int64 {
 }
 
 func (m *mockFileInfo) Mode() os.FileMode {
-	return 0
+	return m.mode
 }
 
 func (m *mockFileInfo) ModTime() time.Time {
@@ -398,7 +403,7 @@ func (m *mockFileInfo) ModTime() time.Time {
 }
 
 func (m *mockFileInfo) IsDir() bool {
-	return m.isDir
+	return m.mode&os.ModeDir != 0
 }
 
 func (m *mockFileInfo) Sys() interface{} {
@@ -407,11 +412,11 @@ func (m *mockFileInfo) Sys() interface{} {
 
 func (m *MockFs) dirToFileInfo(d *mockDir, path string) (info *mockFileInfo) {
 	return &mockFileInfo{
-		path:         path,
+		path:         filepath.Base(path),
 		size:         1,
 		modTime:      d.modTime,
 		permTime:     d.permTime,
-		isDir:        true,
+		mode:         os.ModeDir,
 		inodeNumber:  d.inodeNumber,
 		deviceNumber: m.deviceNumber,
 	}
@@ -420,11 +425,11 @@ func (m *MockFs) dirToFileInfo(d *mockDir, path string) (info *mockFileInfo) {
 
 func (m *MockFs) fileToFileInfo(f *mockFile, path string) (info *mockFileInfo) {
 	return &mockFileInfo{
-		path:         path,
+		path:         filepath.Base(path),
 		size:         1,
 		modTime:      f.modTime,
 		permTime:     f.permTime,
-		isDir:        false,
+		mode:         0,
 		inodeNumber:  f.inodeNumber,
 		deviceNumber: m.deviceNumber,
 	}
@@ -432,11 +437,11 @@ func (m *MockFs) fileToFileInfo(f *mockFile, path string) (info *mockFileInfo) {
 
 func (m *MockFs) linkToFileInfo(l *mockLink, path string) (info *mockFileInfo) {
 	return &mockFileInfo{
-		path:         path,
+		path:         filepath.Base(path),
 		size:         1,
 		modTime:      l.modTime,
 		permTime:     l.permTime,
-		isDir:        false,
+		mode:         os.ModeSymlink,
 		inodeNumber:  l.inodeNumber,
 		deviceNumber: m.deviceNumber,
 	}
@@ -485,6 +490,16 @@ func (m *MockFs) Lstat(path string) (stats os.FileInfo, err error) {
 	}
 }
 
+func (m *MockFs) Stat(path string) (stats os.FileInfo, err error) {
+	// resolve symlinks
+	path, err = m.resolve(path, true)
+	if err != nil {
+		return nil, err
+	}
+
+	return m.Lstat(path)
+}
+
 func (m *MockFs) InodeNumber(info os.FileInfo) (number uint64, err error) {
 	mockInfo, ok := info.(*mockFileInfo)
 	if ok {
diff --git a/finder/fs/fs_test.go b/finder/fs/fs_test.go
new file mode 100644
index 000000000..22a4d7aca
--- /dev/null
+++ b/finder/fs/fs_test.go
@@ -0,0 +1,76 @@
+// Copyright 2020 Google Inc. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package fs
+
+import (
+	"os"
+	"testing"
+)
+
+func TestMockFs_LstatStatSymlinks(t *testing.T) {
+	// setup filesystem
+	filesystem := NewMockFs(nil)
+	Create(t, "/tmp/realdir/hi.txt", filesystem)
+	Create(t, "/tmp/realdir/ignoreme.txt", filesystem)
+
+	Link(t, "/tmp/links/dir", "../realdir", filesystem)
+	Link(t, "/tmp/links/file", "../realdir/hi.txt", filesystem)
+	Link(t, "/tmp/links/broken", "nothingHere", filesystem)
+	Link(t, "/tmp/links/recursive", "recursive", filesystem)
+
+	assertStat := func(t *testing.T, stat os.FileInfo, err error, wantName string, wantMode os.FileMode) {
+		t.Helper()
+		if err != nil {
+			t.Error(err)
+			return
+		}
+		if g, w := stat.Name(), wantName; g != w {
+			t.Errorf("want name %q, got %q", w, g)
+		}
+		if g, w := stat.Mode(), wantMode; g != w {
+			t.Errorf("%s: want mode %q, got %q", wantName, w, g)
+		}
+	}
+
+	assertErr := func(t *testing.T, err error, wantErr string) {
+		if err == nil || err.Error() != wantErr {
+			t.Errorf("want error %q, got %q", wantErr, err)
+		}
+	}
+
+	stat, err := filesystem.Lstat("/tmp/links/dir")
+	assertStat(t, stat, err, "dir", os.ModeSymlink)
+
+	stat, err = filesystem.Stat("/tmp/links/dir")
+	assertStat(t, stat, err, "realdir", os.ModeDir)
+
+	stat, err = filesystem.Lstat("/tmp/links/file")
+	assertStat(t, stat, err, "file", os.ModeSymlink)
+
+	stat, err = filesystem.Stat("/tmp/links/file")
+	assertStat(t, stat, err, "hi.txt", 0)
+
+	stat, err = filesystem.Lstat("/tmp/links/broken")
+	assertStat(t, stat, err, "broken", os.ModeSymlink)
+
+	stat, err = filesystem.Stat("/tmp/links/broken")
+	assertErr(t, err, "stat /tmp/links/nothingHere: file does not exist")
+
+	stat, err = filesystem.Lstat("/tmp/links/recursive")
+	assertStat(t, stat, err, "recursive", os.ModeSymlink)
+
+	stat, err = filesystem.Stat("/tmp/links/recursive")
+	assertErr(t, err, "read /tmp/links/recursive: too many levels of symbolic links")
+}