implement symlinks in unixfs, first draft

License: MIT
Signed-off-by: Jeromy <jeromyj@gmail.com>

files/linkfile.go

+package files
+
+import (
+	"io"
+	"os"
+	"strings"
+)
+
+type Symlink struct {
+	name   string
+	path   string
+	Target string
+	stat   os.FileInfo
+
+	reader io.Reader
+}
+
+func NewLinkFile(name, path, target string, stat os.FileInfo) File {
+	return &Symlink{
+		name:   name,
+		path:   path,
+		Target: target,
+		stat:   stat,
+		reader: strings.NewReader(target),
+	}
+}
+
+func (lf *Symlink) IsDirectory() bool {
+	return false
+}
+
+func (lf *Symlink) NextFile() (File, error) {
+	return nil, io.EOF
+}
+
+func (f *Symlink) FileName() string {
+	return f.name
+}
+
+func (f *Symlink) Close() error {
+	return nil
+}
+
+func (f *Symlink) FullPath() string {
+	return f.path
+}
+
+func (f *Symlink) Read(b []byte) (int, error) {
+	return f.reader.Read(b)
+}

files/multipartfile.go

 package files
 
 import (
+	"io/ioutil"
 	"mime"
 	"mime/multipart"
 	"net/http"
@@ -30,6 +31,17 @@ func NewFileFromPart(part *multipart.Part) (File, error) {
 	}
 
 	contentType := part.Header.Get(contentTypeHeader)
+	if contentType == "symlink" {
+		out, err := ioutil.ReadAll(part)
+		if err != nil {
+			return nil, err
+		}
+
+		return &Symlink{
+			Target: string(out),
+			name:   f.FileName(),
+		}, nil
+	}
 
 	var params map[string]string
 	var err error

files/serialfile.go

@@ -84,10 +84,25 @@ func (f *serialFile) NextFile() (File, error) {
 	// open the next file
 	fileName := fp.Join(f.name, stat.Name())
 	filePath := fp.Join(f.path, stat.Name())
+	st, err := os.Lstat(filePath)
+	if err != nil {
+		return nil, err
+	}
+
+	if st.Mode()&os.ModeSymlink != 0 {
+		f.current = nil
+		target, err := os.Readlink(filePath)
+		if err != nil {
+			return nil, err
+		}
+		return NewLinkFile(fileName, filePath, target, st), nil
+	}
+
 	file, err := os.Open(filePath)
 	if err != nil {
 		return nil, err
 	}
+
 	f.current = file
 
 	// recursively call the constructor on the next file

http/multifilereader.go

@@ -64,13 +64,23 @@ func (mfr *MultiFileReader) Read(buf []byte) (written int, err error) {
 
 		// handle starting a new file part
 		if !mfr.closed {
-			if file.IsDirectory() {
+
+			var contentType string
+			if s, ok := file.(*files.Symlink); ok {
+				mfr.currentFile = s
+
+				// TODO(why): this is a hack. pick a real contentType
+				contentType = "symlink"
+			} else if file.IsDirectory() {
 				// if file is a directory, create a multifilereader from it
 				// (using 'multipart/mixed')
-				mfr.currentFile = NewMultiFileReader(file, false)
+				nmfr := NewMultiFileReader(file, false)
+				mfr.currentFile = nmfr
+				contentType = fmt.Sprintf("multipart/mixed; boundary=%s", nmfr.Boundary())
 			} else {
 				// otherwise, use the file as a reader to read its contents
 				mfr.currentFile = file
+				contentType = "application/octet-stream"
 			}
 
 			// write the boundary and headers
@@ -83,12 +93,7 @@ func (mfr *MultiFileReader) Read(buf []byte) (written int, err error) {
 				header.Set("Content-Disposition", fmt.Sprintf("file; filename=\"%s\"", filename))
 			}
 
-			if file.IsDirectory() {
-				boundary := mfr.currentFile.(*MultiFileReader).Boundary()
-				header.Set("Content-Type", fmt.Sprintf("multipart/mixed; boundary=%s", boundary))
-			} else {
-				header.Set("Content-Type", "application/octet-stream")
-			}
+			header.Set("Content-Type", contentType)
 
 			_, err := mfr.mpWriter.CreatePart(header)
 			if err != nil {