lib/memfs: add method Save and Encode

The Save method will write the new content to file system and update
the content of Node using Encode().

6 files changed, 120 insertions, 0 deletions

diff --git a/.gitignore b/.gitignore
index 01f500b9..69b1ab51 100644
--- a/.gitignore
+++ b/.gitignore
@@ -29,6 +29,7 @@
 /lib/git/testdata/repotest
 /lib/hunspell/testdata/out.dic
 /lib/io/testdata/output.txt
+/lib/memfs/testdata/node_save
 /lib/mining/cmd/cart/cart
 /lib/mining/cmd/crf/crf
 /lib/mining/cmd/lnsmote/lnsmote
diff --git a/lib/memfs/generate_test.go b/lib/memfs/generate_test.go
index 61dad660..8d1bb939 100644
--- a/lib/memfs/generate_test.go
+++ b/lib/memfs/generate_test.go
@@ -11,6 +11,7 @@ func TestGenerate(t *testing.T) {
 		Root: "testdata",
 		Excludes: []string{
 			`^\..*`,
+			".*/node_save$",
 		},
 	}
 	mfs, err := New(opts)
diff --git a/lib/memfs/generate_test/gen_test.go b/lib/memfs/generate_test/gen_test.go
index be1ddb44..d9d19a41 100644
--- a/lib/memfs/generate_test/gen_test.go
+++ b/lib/memfs/generate_test/gen_test.go
@@ -277,6 +277,7 @@ func init() {
 			},
 			Excludes: []string{
 				`^\..*`,
+				`.*/node_save$`,
 			},
 		},
 	}
diff --git a/lib/memfs/memfs_test.go b/lib/memfs/memfs_test.go
index 18dc1eab..4739df99 100644
--- a/lib/memfs/memfs_test.go
+++ b/lib/memfs/memfs_test.go
@@ -74,6 +74,7 @@ func TestNew(t *testing.T) {
 			Excludes: []string{
 				"memfs_generate.go$",
 				"direct$",
+				"node_save$",
 			},
 		},
 		expMapKeys: []string{
@@ -99,6 +100,7 @@ func TestNew(t *testing.T) {
 				`.*\.js$`,
 				"memfs_generate.go$",
 				"direct$",
+				"node_save$",
 			},
 		},
 		expMapKeys: []string{
@@ -123,6 +125,7 @@ func TestNew(t *testing.T) {
 			Excludes: []string{
 				"memfs_generate.go$",
 				"direct$",
+				"node_save$",
 			},
 		},
 		expMapKeys: []string{
diff --git a/lib/memfs/node.go b/lib/memfs/node.go
index c958ea90..849a3d33 100644
--- a/lib/memfs/node.go
+++ b/lib/memfs/node.go
@@ -176,6 +176,39 @@ func (leaf *Node) Decode() ([]byte, error) {
 	return leaf.plainv, nil
 }
 
+//
+// Encode compress and set the content of Node.
+//
+func (leaf *Node) Encode(content []byte) (err error) {
+	logp := "Node.Encode"
+
+	leaf.plainv = content
+	leaf.lowerv = bytes.ToLower(content)
+
+	switch leaf.ContentEncoding {
+	case EncodingGzip:
+		var buf bytes.Buffer
+		gz := gzip.NewWriter(&buf)
+
+		_, err = gz.Write(content)
+		if err != nil {
+			_ = gz.Close()
+			return fmt.Errorf("%s: %w", logp, err)
+		}
+
+		err = gz.Close()
+		if err != nil {
+			return fmt.Errorf("%s: %w", logp, err)
+		}
+
+		leaf.V = libbytes.Copy(buf.Bytes())
+
+	default:
+		leaf.V = content
+	}
+	return nil
+}
+
 func (leaf *Node) IsDir() bool {
 	return leaf.mode.IsDir()
 }
@@ -257,6 +290,36 @@ func (leaf *Node) Readdir(count int) (fis []os.FileInfo, err error) {
 }
 
 //
+// Save the content to file system and update the content of Node.
+//
+func (leaf *Node) Save(content []byte) (err error) {
+	var (
+		logp = "Node.Save"
+		f    *os.File
+	)
+	f, err = os.OpenFile(leaf.SysPath, os.O_WRONLY|os.O_TRUNC, leaf.mode.Perm())
+	if err != nil {
+		return fmt.Errorf("%s: %w", logp, err)
+	}
+	_, err = f.Write(content)
+	if err != nil {
+		return fmt.Errorf("%s: %w", logp, err)
+	}
+	err = f.Close()
+	if err != nil {
+		return fmt.Errorf("%s: %w", logp, err)
+	}
+	err = leaf.Encode(content)
+	if err != nil {
+		return fmt.Errorf("%s: %w", logp, err)
+	}
+
+	leaf.modTime = time.Now()
+	leaf.size = int64(len(content))
+	return nil
+}
+
+//
 // Seek sets the offset for the next Read offset, interpreted according to
 // whence: SeekStart means relative to the start of the file, SeekCurrent
 // means relative to the current offset, and SeekEnd means relative to the
diff --git a/lib/memfs/node_test.go b/lib/memfs/node_test.go
index 5b6375e7..29198055 100644
--- a/lib/memfs/node_test.go
+++ b/lib/memfs/node_test.go
@@ -84,6 +84,7 @@ func TestNode_Readdir(t *testing.T) {
 		"index.css",
 		"index.html",
 		"index.js",
+		"node_save",
 		"plain",
 	}
 
@@ -116,6 +117,56 @@ func gotFileNames(fis []os.FileInfo) (names []string) {
 	return
 }
 
+func TestNode_Save(t *testing.T) {
+	node := &Node{
+		SysPath: "testdata/node_save",
+		mode:    0600,
+	}
+
+	err := os.WriteFile(node.SysPath, []byte{}, node.mode.Perm())
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	cases := []struct {
+		desc            string
+		content         []byte
+		contentEncoding string
+		expContent      []byte
+	}{{
+		desc:       "Without content encoding",
+		content:    []byte("ABC"),
+		expContent: []byte("ABC"),
+	}, {
+		desc:            "With content encoding is gzip",
+		contentEncoding: EncodingGzip,
+		content:         []byte("ABC"),
+		expContent: []byte{
+			0x1f, 0x8b, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00,
+			0x00, 0xff, 0x72, 0x74, 0x72, 0x06, 0x04, 0x00,
+			0x00, 0xff, 0xff, 0x48, 0x03, 0x83, 0xa3, 0x03,
+			0x00, 0x00, 0x00,
+		},
+	}}
+
+	for _, c := range cases {
+		node.ContentEncoding = c.contentEncoding
+
+		err = node.Save(c.content)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		got, err := os.ReadFile(node.SysPath)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		test.Assert(t, c.desc+": file content", c.content, got)
+		test.Assert(t, c.desc+": node content", c.expContent, node.V)
+	}
+}
+
 func TestNode_Seek(t *testing.T) {
 	node := &Node{
 		size: 3,