Update embedfs implementation

- Add chroot functionality to embedfs using billy's chroot helper, enabling compatibility with filesystem operations that require path isolation
- Fix path normalization to support billy's absolute path convention
- Implement Lstat method
- Additional tests to cover embedfs implementation

Author: krrrke

embedfs/chroot_test.go

@@ -0,0 +1,294 @@
+package embedfs
+
+import (
+	"io"
+	"testing"
+
+	"github.com/go-git/go-billy/v6"
+	"github.com/go-git/go-billy/v6/embedfs/internal/testdata"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestChroot_Basic(t *testing.T) {
+	t.Parallel()
+
+	fs := New(testdata.GetTestData())
+
+	// Test chroot to existing directory
+	chrootFS, err := fs.Chroot("testdata")
+	require.NoError(t, err)
+	require.NotNil(t, chrootFS)
+
+	// Test that we can access files in the chrooted filesystem
+	f, err := chrootFS.Open("file1.txt")
+	require.NoError(t, err)
+	defer f.Close()
+
+	content, err := io.ReadAll(f)
+	require.NoError(t, err)
+	assert.Equal(t, "Hello from embedfs!", string(content))
+}
+
+func TestChroot_NestedDirectory(t *testing.T) {
+	t.Parallel()
+
+	fs := New(testdata.GetTestData())
+
+	// Test chroot to nested directory
+	chrootFS, err := fs.Chroot("testdata/subdir")
+	require.NoError(t, err)
+	require.NotNil(t, chrootFS)
+
+	// Test that we can access nested files from the chrooted root
+	f, err := chrootFS.Open("nested.txt")
+	require.NoError(t, err)
+	defer f.Close()
+
+	content, err := io.ReadAll(f)
+	require.NoError(t, err)
+	assert.Equal(t, "Nested file content", string(content))
+}
+
+func TestChroot_StatInChroot(t *testing.T) {
+	t.Parallel()
+
+	fs := New(testdata.GetTestData())
+
+	chrootFS, err := fs.Chroot("testdata")
+	require.NoError(t, err)
+
+	// Test stat on files that exist in chrooted directory
+	fi, err := chrootFS.Stat("file1.txt")
+	require.NoError(t, err)
+	assert.Equal(t, "file1.txt", fi.Name())
+	assert.False(t, fi.IsDir())
+
+	// Test stat on directories that exist in chrooted directory
+	fi, err = chrootFS.Stat("subdir")
+	require.NoError(t, err)
+	assert.Equal(t, "subdir", fi.Name())
+	assert.True(t, fi.IsDir())
+
+	// Test stat with absolute path in chrooted filesystem
+	fi, err = chrootFS.Stat("/file2.txt")
+	require.NoError(t, err)
+	assert.Equal(t, "file2.txt", fi.Name())
+	assert.False(t, fi.IsDir())
+}
+
+func TestChroot_ReadDirInChroot(t *testing.T) {
+	t.Parallel()
+
+	fs := New(testdata.GetTestData())
+
+	chrootFS, err := fs.Chroot("testdata")
+	require.NoError(t, err)
+
+	// Test reading directory contents from chrooted root
+	entries, err := chrootFS.ReadDir("/")
+	require.NoError(t, err)
+
+	expectedFiles := []string{"empty.txt", "file1.txt", "file2.txt", "subdir"}
+	assert.Len(t, entries, len(expectedFiles))
+
+	foundFiles := make(map[string]bool)
+	for _, entry := range entries {
+		foundFiles[entry.Name()] = true
+	}
+
+	for _, expected := range expectedFiles {
+		assert.True(t, foundFiles[expected], "Expected file %s not found", expected)
+	}
+
+	// Test reading subdirectory from chrooted filesystem
+	entries, err = chrootFS.ReadDir("subdir")
+	require.NoError(t, err)
+	assert.Len(t, entries, 1)
+	assert.Equal(t, "nested.txt", entries[0].Name())
+}
+
+func TestChroot_PathNormalization(t *testing.T) {
+	t.Parallel()
+
+	fs := New(testdata.GetTestData())
+
+	// Test chroot with different path formats
+	tests := []struct {
+		name       string
+		chrootPath string
+		openPath   string
+		expectFile string
+	}{
+		{
+			name:       "absolute chroot path",
+			chrootPath: "/testdata",
+			openPath:   "file1.txt",
+			expectFile: "file1.txt",
+		},
+		{
+			name:       "relative chroot path",
+			chrootPath: "testdata",
+			openPath:   "file1.txt",
+			expectFile: "file1.txt",
+		},
+		{
+			name:       "absolute open path in chroot",
+			chrootPath: "testdata",
+			openPath:   "/file1.txt",
+			expectFile: "file1.txt",
+		},
+		{
+			name:       "nested chroot",
+			chrootPath: "testdata/subdir",
+			openPath:   "nested.txt",
+			expectFile: "nested.txt",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			chrootFS, err := fs.Chroot(tt.chrootPath)
+			require.NoError(t, err)
+
+			f, err := chrootFS.Open(tt.openPath)
+			require.NoError(t, err)
+			defer f.Close()
+
+			assert.Equal(t, tt.expectFile, f.Name())
+		})
+	}
+}
+
+func TestChroot_NonExistentPath(t *testing.T) {
+	t.Parallel()
+
+	fs := New(testdata.GetTestData())
+
+	// Test chroot to non-existent directory - billy's chroot helper allows this
+	chrootFS, err := fs.Chroot("nonexistent")
+	require.NoError(t, err)
+	require.NotNil(t, chrootFS)
+
+	// But accessing files within the non-existent chroot should fail
+	_, err = chrootFS.Open("anyfile.txt")
+	assert.Error(t, err)
+}
+
+func TestChroot_Join(t *testing.T) {
+	t.Parallel()
+
+	fs := New(testdata.GetTestData())
+	chrootFS, err := fs.Chroot("testdata")
+	require.NoError(t, err)
+
+	// Test Join operation in chrooted filesystem
+	joined := chrootFS.Join("subdir", "nested.txt")
+	assert.Equal(t, "subdir/nested.txt", joined)
+
+	// Test that joined path can be used to open file
+	f, err := chrootFS.Open(joined)
+	require.NoError(t, err)
+	defer f.Close()
+
+	content, err := io.ReadAll(f)
+	require.NoError(t, err)
+	assert.Equal(t, "Nested file content", string(content))
+}
+
+func TestChroot_UnsupportedOperations(t *testing.T) {
+	t.Parallel()
+
+	fs := New(testdata.GetTestData())
+	chrootFS, err := fs.Chroot("testdata")
+	require.NoError(t, err)
+
+	// Test that write operations still fail in chrooted embedfs
+	_, err = chrootFS.Create("newfile.txt")
+	require.ErrorIs(t, err, billy.ErrReadOnly)
+
+	err = chrootFS.Remove("file1.txt")
+	require.ErrorIs(t, err, billy.ErrReadOnly)
+
+	err = chrootFS.Rename("file1.txt", "renamed.txt")
+	require.ErrorIs(t, err, billy.ErrReadOnly)
+
+	err = chrootFS.MkdirAll("newdir", 0755)
+	require.ErrorIs(t, err, billy.ErrReadOnly)
+}
+
+func TestChroot_NestedChroot(t *testing.T) {
+	t.Parallel()
+
+	fs := New(testdata.GetTestData())
+
+	// Test creating nested chrootfs
+	firstChroot, err := fs.Chroot("testdata")
+	require.NoError(t, err)
+
+	secondChroot, err := firstChroot.Chroot("subdir")
+	require.NoError(t, err)
+
+	// Test that nested chroot works correctly
+	f, err := secondChroot.Open("nested.txt")
+	require.NoError(t, err)
+	defer f.Close()
+
+	content, err := io.ReadAll(f)
+	require.NoError(t, err)
+	assert.Equal(t, "Nested file content", string(content))
+
+	// Test that we can't access parent directory from nested chroot
+	entries, err := secondChroot.ReadDir("/")
+	require.NoError(t, err)
+	assert.Len(t, entries, 1)
+	assert.Equal(t, "nested.txt", entries[0].Name())
+}
+
+func TestChroot_FileOperations(t *testing.T) {
+	t.Parallel()
+
+	fs := New(testdata.GetTestData())
+	chrootFS, err := fs.Chroot("testdata")
+	require.NoError(t, err)
+
+	// Test file operations in chrooted filesystem
+	f, err := chrootFS.Open("file2.txt")
+	require.NoError(t, err)
+	defer f.Close()
+
+	// Test Read
+	buf := make([]byte, 10)
+	n, err := f.Read(buf)
+	require.NoError(t, err)
+	assert.Equal(t, "Another te", string(buf[:n]))
+
+	// Test Seek
+	_, err = f.Seek(0, io.SeekStart)
+	require.NoError(t, err)
+
+	// Test ReadAt
+	buf2 := make([]byte, 7)
+	n, err = f.ReadAt(buf2, 8)
+	require.NoError(t, err)
+	assert.Equal(t, "test fi", string(buf2[:n]))
+
+	// Test that file position wasn't affected by ReadAt
+	n, err = f.Read(buf)
+	require.NoError(t, err)
+	assert.Equal(t, "Another te", string(buf[:n]))
+}
+
+func TestChroot_Lstat(t *testing.T) {
+	t.Parallel()
+
+	fs := New(testdata.GetTestData())
+	chrootFS, err := fs.Chroot("testdata")
+	require.NoError(t, err)
+
+	// Test Lstat in chrooted filesystem (should behave same as Stat for embedfs)
+	fi, err := chrootFS.Lstat("file1.txt")
+	require.NoError(t, err)
+	assert.Equal(t, "file1.txt", fi.Name())
+	assert.False(t, fi.IsDir())
+}

embedfs/embed.go

@@ -13,7 +13,7 @@ import (
 	"sync"
 
 	"github.com/go-git/go-billy/v6"
-	"github.com/go-git/go-billy/v6/memfs"
+	"github.com/go-git/go-billy/v6/helper/chroot"
 )
 
 type Embed struct {
@@ -29,14 +29,29 @@ func New(efs *embed.FS) billy.Filesystem {
 		fs.underlying = &embed.FS{}
 	}
 
-	return fs
+	return chroot.New(fs, "/")
+}
+
+// normalizePath converts billy's absolute paths to embed.FS relative paths
+func (fs *Embed) normalizePath(path string) string {
+	// embed.FS uses "." for root directory, but billy uses "/"
+	if path == "/" {
+		return "."
+	}
+	// Remove leading slash for embed.FS
+	if strings.HasPrefix(path, "/") {
+		return path[1:]
+	}
+	return path
 }
 
 func (fs *Embed) Root() string {
 	return ""
 }
 
 func (fs *Embed) Stat(filename string) (os.FileInfo, error) {
+	filename = fs.normalizePath(filename)
+
 	f, err := fs.underlying.Open(filename)
 	if err != nil {
 		return nil, err
@@ -53,6 +68,7 @@ func (fs *Embed) OpenFile(filename string, flag int, _ os.FileMode) (billy.File,
 		return nil, billy.ErrReadOnly
 	}
 
+	filename = fs.normalizePath(filename)
 	f, err := fs.underlying.Open(filename)
 	if err != nil {
 		return nil, err
@@ -90,7 +106,15 @@ func (fs *Embed) Join(elem ...string) string {
 	return ""
 }
 
+type ByName []os.FileInfo
+
+func (a ByName) Len() int           { return len(a) }
+func (a ByName) Less(i, j int) bool { return a[i].Name() < a[j].Name() }
+func (a ByName) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }
+
 func (fs *Embed) ReadDir(path string) ([]os.FileInfo, error) {
+	path = fs.normalizePath(path)
+
 	e, err := fs.underlying.ReadDir(path)
 	if err != nil {
 		return nil, err
@@ -102,23 +126,14 @@ func (fs *Embed) ReadDir(path string) ([]os.FileInfo, error) {
 		entries = append(entries, fi)
 	}
 
-	sort.Sort(memfs.ByName(entries))
+	sort.Sort(ByName(entries))
 
 	return entries, nil
 }
 
-// Chroot is not supported.
-//
-// Calls will always return billy.ErrNotSupported.
-func (fs *Embed) Chroot(_ string) (billy.Filesystem, error) {
-	return nil, billy.ErrNotSupported
-}
-
-// Lstat is not supported.
-//
-// Calls will always return billy.ErrNotSupported.
-func (fs *Embed) Lstat(_ string) (os.FileInfo, error) {
-	return nil, billy.ErrNotSupported
+// Lstat behaves the same as Stat for embedded filesystems since embed.FS does not support symlinks.
+func (fs *Embed) Lstat(filename string) (os.FileInfo, error) {
+	return fs.Stat(filename)
 }
 
 // Readlink is not supported.