add RemoveAll

RemoveAll delegates to filesystem's RemoveAll if it is implemented.
Otherwise, it falls back to a generic implementation.

Semantics are the same as os.RemoveAll.

fs.go

@@ -65,3 +65,80 @@ func (f *BaseFile) Filename() string {
 func (f *BaseFile) IsClosed() bool {
 	return f.Closed
 }
+
+type removerAll interface {
+	RemoveAll(string) error
+}
+
+// RemoveAll removes path and any children it contains.
+// It removes everything it can but returns the first error
+// it encounters. If the path does not exist, RemoveAll
+// returns nil (no error).
+func RemoveAll(fs Filesystem, path string) error {
+	r, ok := fs.(removerAll)
+	if ok {
+		return r.RemoveAll(path)
+	}
+
+	return removeAll(fs, path)
+}
+
+func removeAll(fs Filesystem, path string) error {
+	// This implementation is adapted from os.RemoveAll.
+
+	// Simple case: if Remove works, we're done.
+	err := fs.Remove(path)
+	if err == nil || os.IsNotExist(err) {
+		return nil
+	}
+
+	// Otherwise, is this a directory we need to recurse into?
+	dir, serr := fs.Stat(path)
+	if serr != nil {
+		if os.IsNotExist(serr) {
+			return nil
+		}
+
+		return serr
+	}
+
+	if !dir.IsDir() {
+		// Not a directory; return the error from Remove.
+		return err
+	}
+
+	// Directory.
+	fis, err := fs.ReadDir(path)
+	if err != nil {
+		if os.IsNotExist(err) {
+			// Race. It was deleted between the Lstat and Open.
+			// Return nil per RemoveAll's docs.
+			return nil
+		}
+
+		return err
+	}
+
+	// Remove contents & return first error.
+	err = nil
+	for _, fi := range fis {
+		cpath := fs.Join(path, fi.Name())
+		err1 := removeAll(fs, cpath)
+		if err == nil {
+			err = err1
+		}
+	}
+
+	// Remove directory.
+	err1 := fs.Remove(path)
+	if err1 == nil || os.IsNotExist(err1) {
+		return nil
+	}
+
+	if err == nil {
+		err = err1
+	}
+
+	return err
+
+}

osfs/os.go

@@ -151,6 +151,13 @@ func (fs *OS) Base() string {
 	return fs.base
 }
 
+// RemoveAll removes a file or directory recursively. Removes everything it can,
+// but returns the first error.
+func (fs *OS) RemoveAll(path string) error {
+	fullpath := fs.Join(fs.base, path)
+	return os.RemoveAll(fullpath)
+}
+
 // osFile represents a file in the os filesystem
 type osFile struct {
 	billy.BaseFile

test/fs_suite.go

@@ -511,3 +511,34 @@ func (s *FilesystemSuite) TestReadWriteLargeFile(c *C) {
 	c.Assert(err, IsNil)
 	c.Assert(len(b), Equals, size)
 }
+
+func (s *FilesystemSuite) TestRemoveAllNonExistent(c *C) {
+	c.Assert(RemoveAll(s.Fs, "non-existent"), IsNil)
+}
+
+func (s *FilesystemSuite) TestRemoveAll(c *C) {
+	fnames := []string{
+		"foo/1",
+		"foo/2",
+		"foo/bar/1",
+		"foo/bar/2",
+		"foo/bar/baz/1",
+		"foo/bar/baz/qux/1",
+		"foo/bar/baz/qux/2",
+		"foo/bar/baz/qux/3",
+	}
+
+	for _, fname := range fnames {
+		f, err := s.Fs.Create(fname)
+		c.Assert(err, IsNil)
+		c.Assert(f.Close(), IsNil)
+	}
+
+	c.Assert(RemoveAll(s.Fs, "foo"), IsNil)
+
+	for _, fname := range fnames {
+		_, err := s.Fs.Stat(fname)
+		comment := Commentf("not removed: %s %s", fname, err)
+		c.Assert(os.IsNotExist(err), Equals, true, comment)
+	}
+}