Merge pull request #766 from jgfrm/nissue25

Add support for extended attributes (e.g. ACL)

Closes #766

src/restic/archiver/archiver.go

@@ -385,7 +385,7 @@ func (arch *Archiver) dirWorker(wg *sync.WaitGroup, p *restic.Progress, done <-c
 			node := &restic.Node{}
 
 			if dir.Path() != "" && dir.Info() != nil {
-				n, err := restic.NodeFromFileInfo(dir.Path(), dir.Info())
+				n, err := restic.NodeFromFileInfo(dir.Fullpath(), dir.Info())
 				if err != nil {
 					n.Error = err.Error()
 					dir.Result() <- n

src/restic/fuse/dir.go

@@ -177,3 +177,21 @@ func (d *dir) Lookup(ctx context.Context, name string) (fs.Node, error) {
 		return nil, fuse.ENOENT
 	}
 }
+
+func (d *dir) Listxattr(ctx context.Context, req *fuse.ListxattrRequest, resp *fuse.ListxattrResponse) error {
+	debug.Log("Listxattr(%v, %v)", d.node.Name, req.Size)
+	for _, attr := range d.node.ExtendedAttributes {
+		resp.Append(attr.Name)
+	}
+	return nil
+}
+
+func (d *dir) Getxattr(ctx context.Context, req *fuse.GetxattrRequest, resp *fuse.GetxattrResponse) error {
+	debug.Log("Getxattr(%v, %v, %v)", d.node.Name, req.Name, req.Size)
+	attrval := d.node.GetExtendedAttribute(req.Name)
+	if attrval != nil {
+		resp.Xattr = attrval
+		return nil
+	}
+	return fuse.ErrNoXattr
+}

src/restic/fuse/file.go

@@ -164,3 +164,21 @@ func (f *file) Release(ctx context.Context, req *fuse.ReleaseRequest) error {
 	}
 	return nil
 }
+
+func (f *file) Listxattr(ctx context.Context, req *fuse.ListxattrRequest, resp *fuse.ListxattrResponse) error {
+	debug.Log("Listxattr(%v, %v)", f.node.Name, req.Size)
+	for _, attr := range f.node.ExtendedAttributes {
+		resp.Append(attr.Name)
+	}
+	return nil
+}
+
+func (f *file) Getxattr(ctx context.Context, req *fuse.GetxattrRequest, resp *fuse.GetxattrResponse) error {
+	debug.Log("Getxattr(%v, %v, %v)", f.node.Name, req.Name, req.Size)
+	attrval := f.node.GetExtendedAttribute(req.Name)
+	if attrval != nil {
+		resp.Xattr = attrval
+		return nil
+	}
+	return fuse.ErrNoXattr
+}

src/restic/node.go

@@ -12,12 +12,18 @@ import (
 
 	"restic/errors"
 
-	"runtime"
+	"bytes"
-
 	"restic/debug"
 	"restic/fs"
+	"runtime"
 )
 
+// ExtendedAttribute is a tuple storing the xattr name and value.
+type ExtendedAttribute struct {
+	Name  string `json:"name"`
+	Value []byte `json:"value"`
+}
+
 // Node is a file, directory or other item in a backup.
 type Node struct {
 	Name               string              `json:"name"`
@@ -34,6 +40,7 @@ type Node struct {
 	Size               uint64              `json:"size,omitempty"`
 	Links              uint64              `json:"links,omitempty"`
 	LinkTarget         string              `json:"linktarget,omitempty"`
+	ExtendedAttributes []ExtendedAttribute `json:"extended_attributes,omitempty"`
 	Device             uint64              `json:"device,omitempty"`
 	Content            IDs                 `json:"content"`
 	Subtree            *ID                 `json:"subtree,omitempty"`
@@ -96,6 +103,16 @@ func nodeTypeFromFileInfo(fi os.FileInfo) string {
 	return ""
 }
 
+// GetExtendedAttribute gets the extended attribute.
+func (node Node) GetExtendedAttribute(a string) []byte {
+	for _, attr := range node.ExtendedAttributes {
+		if attr.Name == a {
+			return attr.Value
+		}
+	}
+	return nil
+}
+
 // CreateAt creates the node at the given path and restores all the meta data.
 func (node *Node) CreateAt(path string, repo Repository, idx *HardlinkIndex) error {
 	debug.Log("create node %v at %v", node.Name, path)
@@ -162,6 +179,22 @@ func (node Node) restoreMetadata(path string) error {
 		}
 	}
 
+	err = node.restoreExtendedAttributes(path)
+	if err != nil {
+		debug.Log("error restoring extended attributes for %v: %v", path, err)
+		return err
+	}
+
+	return nil
+}
+
+func (node Node) restoreExtendedAttributes(path string) error {
+	for _, attr := range node.ExtendedAttributes {
+		err := Setxattr(path, attr.Name, attr.Value)
+		if err != nil {
+			return err
+		}
+	}
 	return nil
 }
 
@@ -350,6 +383,9 @@ func (node Node) Equals(other Node) bool {
 	if !node.sameContent(other) {
 		return false
 	}
+	if !node.sameExtendedAttributes(other) {
+		return false
+	}
 	if node.Subtree != nil {
 		if other.Subtree == nil {
 			return false
@@ -388,6 +424,51 @@ func (node Node) sameContent(other Node) bool {
 			return false
 		}
 	}
+	return true
+}
+
+func (node Node) sameExtendedAttributes(other Node) bool {
+	if len(node.ExtendedAttributes) != len(other.ExtendedAttributes) {
+		return false
+	}
+
+	// build a set of all attributes that node has
+	type mapvalue struct {
+		value   []byte
+		present bool
+	}
+	attributes := make(map[string]mapvalue)
+	for _, attr := range node.ExtendedAttributes {
+		attributes[attr.Name] = mapvalue{value: attr.Value}
+	}
+
+	for _, attr := range other.ExtendedAttributes {
+		v, ok := attributes[attr.Name]
+		if !ok {
+			// extended attribute is not set for node
+			debug.Log("other node has attribute %v, which is not present in node", attr.Name)
+			return false
+
+		}
+
+		if !bytes.Equal(v.value, attr.Value) {
+			// attribute has different value
+			debug.Log("attribute %v has different value", attr.Name)
+			return false
+		}
+
+		// remember that this attribute is present in other.
+		v.present = true
+		attributes[attr.Name] = v
+	}
+
+	// check for attributes that are not present in other
+	for name, v := range attributes {
+		if !v.present {
+			debug.Log("attribute %v not present in other node", name)
+			return false
+		}
+	}
 
 	return true
 }
@@ -497,6 +578,9 @@ func (node *Node) fillExtra(path string, fi os.FileInfo) error {
 		node.LinkTarget, err = fs.Readlink(path)
 		node.Links = uint64(stat.nlink())
 		err = errors.Wrap(err, "Readlink")
+		if err != nil {
+			return err
+		}
 	case "dev":
 		node.Device = uint64(stat.rdev())
 		node.Links = uint64(stat.nlink())
@@ -506,9 +590,32 @@ func (node *Node) fillExtra(path string, fi os.FileInfo) error {
 	case "fifo":
 	case "socket":
 	default:
-		err = errors.Errorf("invalid node type %q", node.Type)
+		return errors.Errorf("invalid node type %q", node.Type)
 	}
 
+	if err = node.fillExtendedAttributes(path); err != nil {
+		return err
+	}
+
+	return err
+}
+
+func (node *Node) fillExtendedAttributes(path string) error {
+	if node.Type == "symlink" {
+		return nil
+	}
+	xattrs, err := Listxattr(path)
+	if err == nil {
+		node.ExtendedAttributes = make([]ExtendedAttribute, len(xattrs))
+		for i, attr := range xattrs {
+			attrVal, err := Getxattr(path, attr)
+			if err != nil {
+				return errors.Errorf("can not obtain extended attribute %v for %v:\n", attr, path)
+			}
+			node.ExtendedAttributes[i].Name = attr
+			node.ExtendedAttributes[i].Value = attrVal
+		}
+	}
 	return err
 }
 

src/restic/node_freebsd.go

@@ -9,3 +9,19 @@ func (node Node) restoreSymlinkTimestamps(path string, utimes [2]syscall.Timespe
 func (s statUnix) atim() syscall.Timespec { return s.Atimespec }
 func (s statUnix) mtim() syscall.Timespec { return s.Mtimespec }
 func (s statUnix) ctim() syscall.Timespec { return s.Ctimespec }
+
+// Getxattr retrieves extended attribute data associated with path.
+func Getxattr(path, name string) ([]byte, error) {
+	return nil, nil
+}
+
+// Listxattr retrieves a list of names of extended attributes associated with the
+// given path in the file system.
+func Listxattr(path string) ([]string, error) {
+	return nil, nil
+}
+
+// Setxattr associates name and data together as an attribute of path.
+func Setxattr(path, name string, data []byte) error {
+	return nil
+}

src/restic/node_openbsd.go

@@ -9,3 +9,19 @@ func (node Node) restoreSymlinkTimestamps(path string, utimes [2]syscall.Timespe
 func (s statUnix) atim() syscall.Timespec { return s.Atim }
 func (s statUnix) mtim() syscall.Timespec { return s.Mtim }
 func (s statUnix) ctim() syscall.Timespec { return s.Ctim }
+
+// Getxattr retrieves extended attribute data associated with path.
+func Getxattr(path, name string) ([]byte, error) {
+	return nil, nil
+}
+
+// Listxattr retrieves a list of names of extended attributes associated with the
+// given path in the file system.
+func Listxattr(path string) ([]string, error) {
+	return nil, nil
+}
+
+// Setxattr associates name and data together as an attribute of path.
+func Setxattr(path, name string, data []byte) error {
+	return nil
+}

src/restic/node_windows.go

@@ -22,6 +22,22 @@ func (node Node) restoreSymlinkTimestamps(path string, utimes [2]syscall.Timespe
 	return nil
 }
 
+// Getxattr retrieves extended attribute data associated with path.
+func Getxattr(path, name string) ([]byte, error) {
+	return nil, nil
+}
+
+// Listxattr retrieves a list of names of extended attributes associated with the
+// given path in the file system.
+func Listxattr(path string) ([]string, error) {
+	return nil, nil
+}
+
+// Setxattr associates name and data together as an attribute of path.
+func Setxattr(path, name string, data []byte) error {
+	return nil
+}
+
 type statWin syscall.Win32FileAttributeData
 
 //ToStatT call the Windows system call Win32FileAttributeData.

src/restic/node_xattr.go

@@ -0,0 +1,38 @@
+// +build !openbsd
+// +build !windows
+// +build !freebsd
+
+package restic
+
+import (
+	"github.com/ivaxer/go-xattr"
+	"syscall"
+)
+
+// Getxattr retrieves extended attribute data associated with path.
+func Getxattr(path, name string) ([]byte, error) {
+	b, e := xattr.Get(path, name)
+	if e == syscall.ENOTSUP {
+		return nil, nil
+	}
+	return b, e
+}
+
+// Listxattr retrieves a list of names of extended attributes associated with the
+// given path in the file system.
+func Listxattr(path string) ([]string, error) {
+	s, e := xattr.List(path)
+	if e == syscall.ENOTSUP {
+		return nil, nil
+	}
+	return s, e
+}
+
+// Setxattr associates name and data together as an attribute of path.
+func Setxattr(path, name string, data []byte) error {
+	e := xattr.Set(path, name, data)
+	if e == syscall.ENOTSUP {
+		return nil
+	}
+	return e
+}

src/restic/tree_test.go

@@ -82,7 +82,7 @@ func TestNodeComparison(t *testing.T) {
 	fi, err := os.Lstat("tree_test.go")
 	OK(t, err)
 
-	node, err := restic.NodeFromFileInfo("foo", fi)
+	node, err := restic.NodeFromFileInfo("tree_test.go", fi)
 	OK(t, err)
 
 	n2 := *node

vendor/manifest

@@ -19,6 +19,12 @@
 			"revision": "76626ae9c91c4f2a10f34cad8ce83ea42c93bb75",
 			"branch": "master"
 		},
+		{
+			"importpath": "github.com/ivaxer/go-xattr",
+			"repository": "https://github.com/ivaxer/go-xattr",
+			"revision": "1a541654d8e447148cf23d472c948f9f0078ac50",
+			"branch": "master"
+		},
 		{
 			"importpath": "github.com/kr/fs",
 			"repository": "https://github.com/kr/fs",

vendor/src/github.com/ivaxer/go-xattr/LICENCE

@@ -0,0 +1,25 @@
+Copyright (c) 2012 Dave Cheney. All rights reserved.
+Copyright (c) 2013 Alexey Palazhchenko. All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+   * Redistributions of source code must retain the above copyright
+notice, this list of conditions and the following disclaimer.
+   * Redistributions in binary form must reproduce the above
+copyright notice, this list of conditions and the following disclaimer
+in the documentation and/or other materials provided with the
+distribution.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

vendor/src/github.com/ivaxer/go-xattr/README.md

@@ -0,0 +1,10 @@
+xattr
+=====
+
+Package xattr provides a simple interface to user extended attributes on Linux and OSX.
+
+Install it: `go get github.com/ivaxer/go-xattr`
+
+Documentation is available on [godoc.org](http://godoc.org/github.com/ivaxer/go-xattr).
+
+License: Simplified BSD License (see LICENSE).

vendor/src/github.com/ivaxer/go-xattr/syscall_darwin.go

@@ -0,0 +1,156 @@
+package xattr
+
+import (
+	"syscall"
+	"unsafe"
+)
+
+func get(path, attr string, buf []byte) (rs int, err error) {
+	return getxattr(path, attr, buf, 0, 0)
+}
+
+// getxattr retrieves value of the extended attribute identified by attr
+// associated with given path in filesystem into buffer buf.
+//
+// options specify options for retrieving extended attributes:
+// - syscall.XATTR_NOFOLLOW
+// - syscall.XATTR_SHOWCOMPRESSION
+//
+// position should be zero. For advanded usage see getxattr(2).
+//
+// On success, buf contains data associated with attr, retrieved value size sz
+// and nil error returned.
+//
+// On error, non-nil error returned. It returns error if buf was to small.
+//
+// A nil slice can be passed as buf to get current size of attribute value,
+// which can be used to estimate buf length for value associated with attr.
+//
+// See getxattr(2) for more details.
+//
+// ssize_t getxattr(const char *path, const char *name, void *value, size_t size, u_int32_t position, int options);
+func getxattr(path, name string, buf []byte, position, options int) (sz int, err error) {
+	p, err := syscall.BytePtrFromString(path)
+	if err != nil {
+		return
+	}
+
+	n, err := syscall.BytePtrFromString(name)
+	if err != nil {
+		return
+	}
+
+	var b *byte
+	if len(buf) > 0 {
+		b = &buf[0]
+	}
+
+	r0, _, e1 := syscall.Syscall6(syscall.SYS_GETXATTR,
+		uintptr(unsafe.Pointer(p)),
+		uintptr(unsafe.Pointer(n)),
+		uintptr(unsafe.Pointer(b)),
+		uintptr(len(buf)),
+		uintptr(position),
+		uintptr(options))
+
+	sz = int(r0)
+	if e1 != 0 {
+		err = e1
+	}
+
+	return
+}
+
+func list(path string, dest []byte) (sz int, err error) {
+	return listxattr(path, dest, 0)
+}
+
+// ssize_t listxattr(const char *path, char *namebuf, size_t size, int options);
+func listxattr(path string, buf []byte, options int) (sz int, err error) {
+	p, err := syscall.BytePtrFromString(path)
+	if err != nil {
+		return
+	}
+
+	var b *byte
+	if len(buf) > 0 {
+		b = &buf[0]
+	}
+
+	r0, _, e1 := syscall.Syscall6(syscall.SYS_LISTXATTR,
+		uintptr(unsafe.Pointer(p)),
+		uintptr(unsafe.Pointer(b)),
+		uintptr(len(buf)),
+		uintptr(options), 0, 0)
+
+	sz = int(r0)
+	if e1 != 0 {
+		err = e1
+	}
+
+	return
+}
+
+func set(path, attr string, data []byte, flags int) error {
+	return setxattr(path, attr, data, 0, flags)
+}
+
+// int setxattr(const char *path, const char *name, void *value, size_t size, u_int32_t position, int options);
+func setxattr(path string, name string, data []byte, position, options int) (err error) {
+	p, err := syscall.BytePtrFromString(path)
+	if err != nil {
+		return
+	}
+
+	n, err := syscall.BytePtrFromString(name)
+	if err != nil {
+		return
+	}
+
+	var b *byte
+	if len(data) > 0 {
+		b = &data[0]
+	}
+
+	_, _, e1 := syscall.Syscall6(syscall.SYS_SETXATTR,
+		uintptr(unsafe.Pointer(p)),
+		uintptr(unsafe.Pointer(n)),
+		uintptr(unsafe.Pointer(b)),
+		uintptr(len(data)),
+		uintptr(position),
+		uintptr(options))
+
+	if e1 != 0 {
+		err = e1
+	}
+
+	return
+}
+
+func remove(path, attr string) error {
+	return removexattr(path, attr, 0)
+}
+
+// int removexattr(const char *path, const char *name, int options);
+func removexattr(path string, name string, options int) (err error) {
+	p, err := syscall.BytePtrFromString(path)
+	if err != nil {
+		return
+	}
+
+	n, err := syscall.BytePtrFromString(name)
+	if err != nil {
+		return
+	}
+
+	_, _, e1 := syscall.Syscall(syscall.SYS_REMOVEXATTR,
+		uintptr(unsafe.Pointer(p)),
+		uintptr(unsafe.Pointer(n)),
+		uintptr(options))
+
+	if e1 != 0 {
+		err = e1
+	}
+
+	return
+}

vendor/src/github.com/ivaxer/go-xattr/syscall_linux.go

@@ -0,0 +1,21 @@
+package xattr
+
+import (
+	"syscall"
+)
+
+func get(path, attr string, dest []byte) (sz int, err error) {
+	return syscall.Getxattr(path, attr, dest)
+}
+
+func list(path string, dest []byte) (sz int, err error) {
+	return syscall.Listxattr(path, dest)
+}
+
+func set(path, attr string, data []byte, flags int) error {
+	return syscall.Setxattr(path, attr, data, flags)
+}
+
+func remove(path, attr string) error {
+	return syscall.Removexattr(path, attr)
+}

vendor/src/github.com/ivaxer/go-xattr/xattr.go

@@ -0,0 +1,171 @@
+// Package xattr provides a simple interface to user extended attributes on
+// Linux and OSX. Support for xattrs is filesystem dependant, so not a given
+// even if you are running one of those operating systems.
+//
+// On Linux you have to edit /etc/fstab to include "user_xattr". Also, on Linux
+// user's extended attributes have a manditory prefix of "user.".
+package xattr
+
+import (
+	"os"
+)
+
+// IsNotExist returns a boolean indicating whether the error is known to report
+// that an extended attribute does not exist.
+func IsNotExist(err error) bool {
+	if e, ok := err.(*os.PathError); ok {
+		err = e.Err
+	}
+
+	return isNotExist(err)
+}
+
+// Converts an array of NUL terminated UTF-8 strings
+// to a []string.
+func nullTermToStrings(buf []byte) (result []string) {
+	offset := 0
+	for index, b := range buf {
+		if b == 0 {
+			result = append(result, string(buf[offset:index]))
+			offset = index + 1
+		}
+	}
+	return
+}
+
+// Getxattr retrieves value of the extended attribute identified by attr
+// associated with given path in filesystem into buffer dest.
+//
+// On success, dest contains data associated with attr, retrieved value size sz
+// and nil error are returned.
+//
+// On error, non-nil error is returned. Getxattr returns error if dest was too
+// small for attribute value.
+//
+// A nil slice can be passed as dest to get current size of attribute value,
+// which can be used to estimate dest length for value associated with attr.
+//
+// See getxattr(2) for more information.
+//
+// Get is high-level function on top of Getxattr. Getxattr more efficient,
+// because it issues one syscall per call, doesn't allocate memory for
+// attribute data (caller can reuse buffer).
+func Getxattr(path, attr string, dest []byte) (sz int, err error) {
+	return get(path, attr, dest)
+}
+
+// Get retrieves extended attribute data associated with path. If there is an
+// error, it will be of type *os.PathError.
+//
+// See Getxattr for low-level usage.
+func Get(path, attr string) ([]byte, error) {
+	// find size
+	size, err := Getxattr(path, attr, nil)
+	if err != nil {
+		return nil, &os.PathError{"getxattr", path, err}
+	}
+	if size == 0 {
+		return []byte{}, nil
+	}
+
+	// read into buffer of that size
+	buf := make([]byte, size)
+	size, err = Getxattr(path, attr, buf)
+	if err != nil {
+		return nil, &os.PathError{"getxattr", path, err}
+	}
+	return buf[:size], nil
+}
+
+// Listxattr retrieves the list of extended attribute names associated with
+// path. The list is set of NULL-terminated names.
+//
+// On success, dest containes list of NULL-terminated names, the length of the
+// extended attribute list and nil error are returned.
+//
+// On error, non nil error is returned. Listxattr returns error if dest buffer
+// was too small for extended attribute list.
+//
+// The list of names is returned as an unordered array of NULL-terminated
+// character strings (attribute names are separated by NULL characters), like
+// this:
+//     user.name1\0system.name1\0user.name2\0
+//
+// A nil slice can be passed as dest to get the current size of the list of
+// extended attribute names, which can be used to estimate dest length for
+// the list of names.
+//
+// See listxattr(2) for more information.
+//
+// List is high-level function on top of Listxattr.
+func Listxattr(path string, dest []byte) (sz int, err error) {
+	return list(path, dest)
+}
+
+// List retrieves a list of names of extended attributes associated with path.
+// If there is an error, it will be of type *os.PathError.
+//
+// See Listxattr for low-level usage.
+func List(path string) ([]string, error) {
+	// find size
+	size, err := Listxattr(path, nil)
+	if err != nil {
+		return nil, &os.PathError{"listxattr", path, err}
+	}
+	if size == 0 {
+		return []string{}, nil
+	}
+
+	// read into buffer of that size
+	buf := make([]byte, size)
+	size, err = Listxattr(path, buf)
+	if err != nil {
+		return nil, &os.PathError{"listxattr", path, err}
+	}
+	return nullTermToStrings(buf[:size]), nil
+}
+
+// Setxattr sets value in data of extended attribute attr and accosiated with
+// path.
+//
+// The flags refine the semantic of the operation. XATTR_CREATE specifies pure
+// create, which fails if attr already exists. XATTR_REPLACE  specifies a pure
+// replace operation, which fails if the attr does not already exist. By
+// default (no flags), the attr will be created if need be, or will simply
+// replace the value if attr exists.
+//
+// On error, non nil error is returned.
+//
+// See setxattr(2) for more information.
+func Setxattr(path, attr string, data []byte, flags int) error {
+	return set(path, attr, data, flags)
+}
+
+// Set associates data as an extended attribute of path. If there is an error,
+// it will be of type *os.PathError.
+//
+// See Setxattr for low-level usage.
+func Set(path, attr string, data []byte) error {
+	if err := Setxattr(path, attr, data, 0); err != nil {
+		return &os.PathError{"setxattr", path, err}
+	}
+	return nil
+}
+
+// Removexattr removes the extended attribute attr accosiated with path.
+//
+// On error, non-nil error is returned.
+//
+// See removexattr(2) for more information.
+func Removexattr(path, attr string) error {
+	return remove(path, attr)
+}
+
+// Remove removes the extended attribute. If there is an error, it will be of
+// type *os.PathError.
+func Remove(path, attr string) error {
+	if err := Removexattr(path, attr); err != nil {
+		return &os.PathError{"removexattr", path, err}
+	}
+	return nil
+}

vendor/src/github.com/ivaxer/go-xattr/xattr_darwin.go

@@ -0,0 +1,9 @@
+package xattr
+
+import (
+	"syscall"
+)
+
+func isNotExist(err error) bool {
+	return err == syscall.ENOATTR
+}

vendor/src/github.com/ivaxer/go-xattr/xattr_linux.go

@@ -0,0 +1,9 @@
+package xattr
+
+import (
+	"syscall"
+)
+
+func isNotExist(err error) bool {
+	return err == syscall.ENODATA
+}

vendor/src/github.com/ivaxer/go-xattr/xattr_test.go

@@ -0,0 +1,153 @@
+package xattr
+
+import (
+	"bytes"
+	"io/ioutil"
+	"os"
+	"sort"
+	"testing"
+)
+
+var tmpdir = os.Getenv("TEST_XATTR_PATH")
+
+func mktemp(t *testing.T) *os.File {
+	file, err := ioutil.TempFile(tmpdir, "test_xattr_")
+	if err != nil {
+		t.Fatalf("TempFile() failed: %v", err)
+	}
+
+	return file
+}
+
+func stringsEqual(got, expected []string) bool {
+	if len(got) != len(expected) {
+		return false
+	}
+
+	for i := range got {
+		if got[i] != expected[i] {
+			return false
+		}
+	}
+
+	return true
+}
+
+// expected must be sorted slice of attribute names.
+func checkList(t *testing.T, path string, expected []string) {
+	got, err := List(path)
+	if err != nil {
+		t.Fatalf("List(%q) failed: %v", path, err)
+	}
+
+	sort.Strings(got)
+
+	if !stringsEqual(got, expected) {
+		t.Errorf("List(%q): expected %v, got %v", path, got, expected)
+	}
+}
+
+func checkListError(t *testing.T, path string, f func(error) bool) {
+	got, err := List(path)
+	if !f(err) {
+		t.Errorf("List(%q): unexpected error value: %v", path, err)
+	}
+
+	if got != nil {
+		t.Error("List(): expected nil slice on error")
+	}
+}
+
+func checkSet(t *testing.T, path, attr string, data []byte) {
+	if err := Set(path, attr, data); err != nil {
+		t.Fatalf("Set(%q, %q, %v) failed: %v", path, attr, data, err)
+	}
+}
+
+func checkSetError(t *testing.T, path, attr string, data []byte, f func(error) bool) {
+	if err := Set(path, attr, data); !f(err) {
+		t.Fatalf("Set(%q, %q, %v): unexpected error value: %v", path, attr, data, err)
+	}
+}
+
+func checkGet(t *testing.T, path, attr string, expected []byte) {
+	got, err := Get(path, attr)
+	if err != nil {
+		t.Fatalf("Get(%q, %q) failed: %v", path, attr, err)
+	}
+
+	if !bytes.Equal(got, expected) {
+		t.Errorf("Get(%q, %q): got %v, expected %v", path, attr, got, expected)
+	}
+}
+
+func checkGetError(t *testing.T, path, attr string, f func(error) bool) {
+	got, err := Get(path, attr)
+	if !f(err) {
+		t.Errorf("Get(%q, %q): unexpected error value: %v", path, attr, err)
+	}
+
+	if got != nil {
+		t.Error("Get(): expected nil slice on error")
+	}
+}
+
+func checkRemove(t *testing.T, path, attr string) {
+	if err := Remove(path, attr); err != nil {
+		t.Fatalf("Remove(%q, %q) failed: %v", path, attr, err)
+	}
+}
+
+func checkRemoveError(t *testing.T, path, attr string, f func(error) bool) {
+	if err := Remove(path, attr); !f(err) {
+		t.Errorf("Remove(%q, %q): unexpected error value: %v", path, attr, err)
+	}
+}
+
+func TestFlow(t *testing.T) {
+	f := mktemp(t)
+	defer func() { f.Close(); os.Remove(f.Name()) }()
+
+	path := f.Name()
+	data := []byte("test xattr data")
+	attr := "user.test xattr"
+	attr2 := "user.text xattr 2"
+
+	checkList(t, path, []string{})
+	checkSet(t, path, attr, data)
+	checkList(t, path, []string{attr})
+	checkSet(t, path, attr2, data)
+	checkList(t, path, []string{attr, attr2})
+	checkGet(t, path, attr, data)
+	checkGetError(t, path, "user.unknown attr", IsNotExist)
+	checkRemove(t, path, attr)
+	checkList(t, path, []string{attr2})
+	checkRemove(t, path, attr2)
+	checkList(t, path, []string{})
+}
+
+func TestEmptyAttr(t *testing.T) {
+	f := mktemp(t)
+	defer func() { f.Close(); os.Remove(f.Name()) }()
+
+	path := f.Name()
+	attr := "user.test xattr"
+	data := []byte{}
+
+	checkSet(t, path, attr, data)
+	checkList(t, path, []string{attr})
+	checkGet(t, path, attr, []byte{})
+	checkRemove(t, path, attr)
+	checkList(t, path, []string{})
+}
+
+func TestNoFile(t *testing.T) {
+	path := "no-such-file"
+	attr := "user.test xattr"
+	data := []byte("test_xattr data")
+
+	checkListError(t, path, os.IsNotExist)
+	checkSetError(t, path, attr, data, os.IsNotExist)
+	checkGetError(t, path, attr, os.IsNotExist)
+	checkRemoveError(t, path, attr, os.IsNotExist)
+}