Fix symlink behaviour (#1020)

* Fix symlink behaviour

Make sure to evaluate symlinks when the path is not absolute and not
local. Otherwise just fall back to regular absolute paths.

Signed-off-by: Zoltán Reegn <zoltan.reegn@gmail.com>

pkg/filesystem/fs.go

@@ -34,17 +34,18 @@ type FileSystem struct {
 	Getwd             func() (string, error)
 	Chdir             func(string) error
 	Abs               func(string) (string, error)
+	EvalSymlinks      func(string) (string, error)
 }
 
 func DefaultFileSystem() *FileSystem {
 	dfs := FileSystem{
-		ReadDir:    os.ReadDir,
-		DeleteFile: os.Remove,
-		Stat:       os.Stat,
-		Glob:       filepath.Glob,
-		Getwd:      os.Getwd,
-		Chdir:      os.Chdir,
-		Abs:        filepath.Abs,
+		ReadDir:      os.ReadDir,
+		DeleteFile:   os.Remove,
+		Stat:         os.Stat,
+		Glob:         filepath.Glob,
+		Getwd:        os.Getwd,
+		Chdir:        os.Chdir,
+		EvalSymlinks: filepath.EvalSymlinks,
 	}
 
 	dfs.Stat = dfs.stat
@@ -52,6 +53,7 @@ func DefaultFileSystem() *FileSystem {
 	dfs.FileExistsAt = dfs.fileExistsAtDefault
 	dfs.DirectoryExistsAt = dfs.directoryExistsDefault
 	dfs.FileExists = dfs.fileExistsDefault
+	dfs.Abs = dfs.absDefault
 	return &dfs
 }
 
@@ -91,7 +93,9 @@ func FromFileSystem(params FileSystem) *FileSystem {
 	if params.Abs != nil {
 		dfs.Abs = params.Abs
 	}
-
+	if params.EvalSymlinks != nil {
+		dfs.EvalSymlinks = params.EvalSymlinks
+	}
 	return dfs
 }
 
@@ -110,13 +114,20 @@ func (filesystem *FileSystem) readFile(name string) ([]byte, error) {
 }
 
 func (filesystem *FileSystem) fileExistsAtDefault(path string) bool {
+	path, err := filesystem.resolveSymlinks(path)
+	if err != nil {
+		return false
+	}
 	fileInfo, err := filesystem.Stat(path)
 	return err == nil && fileInfo.Mode().IsRegular()
 }
 
 func (filesystem *FileSystem) fileExistsDefault(path string) (bool, error) {
-	_, err := filesystem.Stat(path)
-
+	path, err := filesystem.resolveSymlinks(path)
+	if err != nil {
+		return false, err
+	}
+	_, err = filesystem.Stat(path)
 	if err != nil {
 		if os.IsNotExist(err) {
 			return false, nil
@@ -127,6 +138,38 @@ func (filesystem *FileSystem) fileExistsDefault(path string) (bool, error) {
 }
 
 func (filesystem *FileSystem) directoryExistsDefault(path string) bool {
+	path, err := filesystem.resolveSymlinks(path)
+	if err != nil {
+		return false
+	}
 	fileInfo, err := filesystem.Stat(path)
 	return err == nil && fileInfo.Mode().IsDir()
 }
+
+func (filesystem *FileSystem) resolveSymlinks(path string) (string, error) {
+	if !filepath.IsAbs(path) && !filepath.IsLocal(path) {
+		basePath, err := filesystem.Getwd()
+		if err != nil {
+			return "", err
+		}
+
+		basePath, err = filesystem.EvalSymlinks(basePath)
+		if err != nil {
+			return "", err
+		}
+		path, err := filesystem.EvalSymlinks(filepath.Join(basePath, path))
+		if err != nil {
+			return "", err
+		}
+		return path, nil
+	}
+	return path, nil
+}
+
+func (filesystem *FileSystem) absDefault(path string) (string, error) {
+	path, err := filesystem.resolveSymlinks(path)
+	if err != nil {
+		return "", err
+	}
+	return filepath.Abs(path)
+}

pkg/filesystem/fs_test.go

@@ -12,28 +12,58 @@ import (
 func NewTestFileSystem() FileSystem {
 	replaceffs := FileSystem{
 		Stat: func(s string) (os.FileInfo, error) {
-			if strings.HasPrefix(s, "existing_file") {
+			if strings.HasSuffix(s, "existing_file.txt") {
 				return fileStat{mode: 0}, nil
 			}
-			if strings.HasPrefix(s, "existing_dir") {
+			if strings.HasSuffix(s, "existing_dir") {
 				return fileStat{mode: fs.ModeDir}, nil
 			}
 			return nil, errors.New("Error")
 		},
+		Getwd: func() (string, error) {
+			return "/test/dir", nil
+		},
+		EvalSymlinks: func(s string) (string, error) {
+			if s == "/test/dir" {
+				return "/real/dir", nil
+			} else {
+				return s, nil
+			}
+		},
 	}
 	return *FromFileSystem(replaceffs)
 }
 
+func TestFs_resolveSymlinks(t *testing.T) {
+	ffs := NewTestFileSystem()
+	path, _ := ffs.resolveSymlinks("../existing_file.txt")
+	if path != "/real/existing_file.txt" {
+		t.Errorf("Expected absolute path %s but got %s", "/real/existing_file.txt", path)
+	}
+	path, _ = ffs.resolveSymlinks("./existing_file.txt")
+	if path != "./existing_file.txt" {
+		t.Errorf("Expected local path %s but got %s", "./existing_file.txt", path)
+	}
+	path, _ = ffs.resolveSymlinks("existing_file.txt")
+	if path != "existing_file.txt" {
+		t.Errorf("Expected local path %s but got %s", "existing_file.txt", path)
+	}
+	path, _ = ffs.resolveSymlinks("/a/b/c/existing_file.txt")
+	if path != "/a/b/c/existing_file.txt" {
+		t.Errorf("Expected absolute path %s but got %s", "/a/b/c/existing_file.txt", path)
+	}
+}
+
 func TestFs_fileExistsDefault(t *testing.T) {
 	ffs := NewTestFileSystem()
-	var exists, _ = ffs.FileExists("existing_file.txt")
+	exists, _ := ffs.FileExists("existing_file.txt")
 	if !exists {
 		t.Errorf("Expected file %s, not found", "existing_file.txt")
 	}
 
-	exists, _ = ffs.FileExists("non_existing_file.txt")
+	exists, _ = ffs.FileExists("missing_file.txt")
 	if exists {
-		t.Errorf("Not expected file %s, found", "non_existing_file.txt")
+		t.Errorf("Not expected file %s, found", "missing_file.txt")
 	}
 
 	dfs := DefaultFileSystem()
@@ -46,14 +76,14 @@ func TestFs_fileExistsDefault(t *testing.T) {
 func TestFs_fileExistsAtDefault(t *testing.T) {
 	ffs := NewTestFileSystem()
 
-	var exists = ffs.FileExistsAt("existing_file.txt")
+	exists := ffs.FileExistsAt("existing_file.txt")
 	if !exists {
 		t.Errorf("Expected file %s, not found", "existing_file.txt")
 	}
 
-	exists = ffs.FileExistsAt("non_existing_file.txt")
+	exists = ffs.FileExistsAt("missing_file.txt")
 	if exists {
-		t.Errorf("Not expected file %s, found", "non_existing_file.txt")
+		t.Errorf("Not expected file %s, found", "missing_file.txt")
 	}
 
 	exists = ffs.FileExistsAt("existing_dir")
@@ -70,12 +100,12 @@ func TestFs_fileExistsAtDefault(t *testing.T) {
 
 func TestFs_directoryExistsDefault(t *testing.T) {
 	ffs := NewTestFileSystem()
-	var exists = ffs.DirectoryExistsAt("existing_dir")
+	exists := ffs.DirectoryExistsAt("existing_dir")
 	if !exists {
 		t.Errorf("Expected file %s, not found", "existing_dir")
 	}
 
-	exists = ffs.DirectoryExistsAt("not_existing_dir")
+	exists = ffs.DirectoryExistsAt("missing_dir")
 	if exists {
 		t.Errorf("Not expected file %s, found", "existing_dir")
 	}
@@ -148,7 +178,8 @@ func TestFs_DefaultBuilder(t *testing.T) {
 		ffs.Stat == nil ||
 		ffs.Getwd == nil ||
 		ffs.Chdir == nil ||
-		ffs.Abs == nil {
+		ffs.Abs == nil ||
+		ffs.EvalSymlinks == nil {
 		t.Errorf("Missing functions in DefaultFileSystem")
 	}
 }