add symlink support

README.md

@@ -0,0 +1,14 @@
+# vfscopy
+
+Copy a Virtual FileSystem, such as
+[http.FileSystem](https://golang.org/pkg/net/http/#FileSystem),
+recursively to a native file system destination.
+
+```go
+httpfs := http.Dir("/tmp/public/")
+vfs := vfscopy.NewVFS(httpfs)
+
+if err := Copy(vfs, ".", "/tmp/dst/"); nil != err {
+    fmt.Fprintf(os.Stderr, "couldn't copy vfs: %v\n", err)
+}
+```

copy.go

@@ -2,6 +2,7 @@ package vfscopy
 
 import (
 	"io"
+	"fmt"
 	"os"
 	"path/filepath"
 )
@@ -33,9 +34,9 @@ func switchboard(
 	vfs FileSystem, src, dest string, f File, info os.FileInfo, opt Options,
 ) error {
 	switch {
-	//case info.Mode()&os.ModeSymlink != 0:
+	case info.Mode()&os.ModeSymlink != 0:
 		// TODO
-		//return onsymlink(vfs, src, dest, opt)
+		return onsymlink(vfs, src, dest, opt)
 	case info.IsDir():
 		return dcopy(vfs, src, dest, f, info, opt)
 	default:
@@ -130,39 +131,40 @@ func dcopy(vfs FileSystem, srcdir, destdir string, d File, info os.FileInfo, opt
 	return
 }
 
-/*
 func onsymlink(vfs FileSystem, src, dest string, opt Options) error {
+	fmt.Println("lstat happy")
 	switch opt.OnSymlink(src) {
 	case Shallow:
 		return lcopy(vfs, src, dest)
 	case Deep:
-		orig, err := filepath.EvalSymlinks(src)
+		orig, err := vfs.EvalSymlinks(src)
 		if err != nil {
 			return err
 		}
-		info, err := os.Lstat(orig)
+		f, err := vfs.Open(orig)
 		if err != nil {
 			return err
 		}
-		return copy(vfs, orig, dest, info, opt)
+		//info, err := os.Lstat(orig)
+		info, err := f.Stat()
+		if err != nil {
+			return err
+		}
+		return copy(vfs, orig, dest, f, info, opt)
 	case Skip:
 		fallthrough
 	default:
 		return nil // do nothing
 	}
 }
-*/
 
 // lcopy is for a symlink,
 // with just creating a new symlink by replicating src symlink.
 func lcopy(vfs FileSystem, src, dest string) error {
-	/*
-	// TODO
-	src, err := os.Readlink(src)
+	src, err := vfs.Readlink(src)
 	if err != nil {
 		return err
 	}
-	*/
 
 	// Create the directories on the path to the dest symlink.
 	if err := os.MkdirAll(filepath.Dir(dest), os.ModePerm); err != nil {

vfs.go

@@ -9,9 +9,16 @@ import (
 	"errors"
 )
 
-// FileSystem is copied from http.FileSystem
+// HTTPFileSystem is copied from http.FileSystem
+type HTTPFileSystem interface {
+    Open(name string) (File, error)
+}
+
+// FileSystem is a Virtual FileSystem with Symlink support
 type FileSystem interface {
     Open(name string) (File, error)
+	Readlink(name string) (string, error)
+	EvalSymlinks(name string) (string, error)
 }
 
 // File is copied from http.File
@@ -23,6 +30,33 @@ type File interface {
     Stat() (os.FileInfo, error)
 }
 
+// VFS is a virtual FileSystem with possible Symlink support
+type VFS struct {
+	FileSystem HTTPFileSystem
+}
+
+// Open opens a file relative to a virtual filesystem
+func (v *VFS) Open(name string) (File, error) {
+	return v.Open(name)
+}
+
+// Readlink returns a "not implemented" error,
+// which is okay because it is never called for http.FileSystem.
+func (v *VFS) Readlink(name string) (string, error) {
+	return "", errors.New("not implemented")
+}
+
+// EvalSymlinks returns the original name,
+// which is okay because it is never called for http.FileSystem.
+func (v *VFS) EvalSymlinks(name string) (string, error) {
+	return name, nil
+}
+
+// NewVFS gives an http.FileSystem faux symlink support
+func NewVFS(httpfs HTTPFileSystem) FileSystem {
+	return &VFS{ FileSystem: httpfs }
+}
+
 // Dir is an implementation of a Virtual FileSystem
 type Dir string
 
@@ -50,19 +84,53 @@ func mapDirOpenError(originalErr error, name string) error {
 	return originalErr
 }
 
-// Open opens a file relative to a virtual filesystem
-func (d Dir) Open(name string) (File, error) {
+func (d Dir) fullName(name string) (string, error) {
 	if filepath.Separator != '/' && strings.ContainsRune(name, filepath.Separator) {
-		return nil, errors.New("http: invalid character in file path")
+		return "", errors.New("http: invalid character in file path")
 	}
 	dir := string(d)
 	if dir == "" {
 		dir = "."
 	}
 	fullName := filepath.Join(dir, filepath.FromSlash(path.Clean("/"+name)))
+	return fullName, nil
+}
+
+// Open opens a file relative to a virtual filesystem
+func (d Dir) Open(name string) (File, error) {
+	fullName, err := d.fullName(name)
+	if nil != err {
+		return nil, err
+	}
 	f, err := os.Open(fullName)
 	if err != nil {
 		return nil, mapDirOpenError(err, fullName)
 	}
 	return f, nil
 }
+
+// Readlink returns the destination of the named symbolic link.
+func (d Dir) Readlink(name string) (string, error) {
+	name, err := d.fullName(name)
+	if nil != err {
+		return "", err
+	}
+	name, err = os.Readlink(name)
+	if err != nil {
+		return "", mapDirOpenError(err, name)
+	}
+	return name, nil
+}
+
+// EvalSymlinks returns the destination of the named symbolic link.
+func (d Dir) EvalSymlinks(name string) (string, error) {
+	name, err := d.fullName(name)
+	if nil != err {
+		return "", err
+	}
+	name, err = filepath.EvalSymlinks(name)
+	if err != nil {
+		return "", mapDirOpenError(err, name)
+	}
+	return name, nil
+}