Update github.com/pkg/xattr

Closes #843

vendor/manifest

@@ -52,7 +52,7 @@
 		{
 			"importpath": "github.com/pkg/xattr",
 			"repository": "https://github.com/pkg/xattr",
-			"revision": "1d40b70a947cd8e8457e4715e1123f8e99f5f241",
+			"revision": "b867675798fa7708a444945602b452ca493f2272",
 			"branch": "master"
 		},
 		{

vendor/src/github.com/pkg/xattr/README.md

@@ -1,3 +1,7 @@
+[![GoDoc](https://godoc.org/github.com/pkg/xattr?status.svg)](http://godoc.org/github.com/pkg/xattr)
+[![Go Report Card](https://goreportcard.com/badge/github.com/pkg/xattr)](https://goreportcard.com/report/github.com/pkg/xattr)
+[![Build Status](https://travis-ci.org/pkg/xattr.svg?branch=master)](https://travis-ci.org/pkg/xattr)
+
 xattr
 =====
 Extended attribute support for Go (linux + darwin + freebsd).
@@ -10,12 +14,12 @@ Extended attribute support for Go (linux + darwin + freebsd).
   const path = "/tmp/myfile"
   const prefix = "user."
 
-  if err = Setxattr(path, prefix+"test", []byte("test-attr-value")); err != nil {
-    t.Fatal(err)
+  if err := xattr.Setxattr(path, prefix+"test", []byte("test-attr-value")); err != nil {
+    log.Fatal(err)
   }
 
   var data []byte
-  data, err = Getxattr(path, prefix+"test"); err != nil {
-    t.Fatal(err)
+  data, err = xattr.Getxattr(path, prefix+"test"); err != nil {
+    log.Fatal(err)
   }
 ```

vendor/src/github.com/pkg/xattr/xattr.go

@@ -1,3 +1,10 @@
+/*
+Package xattr provides support for extended attributes on linux, darwin and freebsd.
+Extended attributes are name:value pairs associated permanently with files and directories, 
+similar to the environment strings associated with a process. 
+An attribute may be defined or undefined. If it is defined, its value may be empty or non-empty.
+More details you can find here: https://en.wikipedia.org/wiki/Extended_file_attributes
+*/
 package xattr
 
 // XAttrError records an error and the operation, file path and attribute that caused it.
@@ -12,8 +19,7 @@ func (e *XAttrError) Error() string {
 	return e.Op + " " + e.Path + " " + e.Name + ": " + e.Err.Error()
 }
 
-// Convert an array of NULL terminated UTF-8 strings
-// to a []string.
+// nullTermToStrings converts an array of NULL terminated UTF-8 strings to a []string.
 func nullTermToStrings(buf []byte) (result []string) {
 	offset := 0
 	for index, b := range buf {

vendor/src/github.com/pkg/xattr/xattr_darwin.go

@@ -2,44 +2,47 @@
 
 package xattr
 
-// Retrieve extended attribute data associated with path.
+// Getxattr retrieves extended attribute data associated with path.
 func Getxattr(path, name string) ([]byte, error) {
 	// find size.
 	size, err := getxattr(path, name, nil, 0, 0, 0)
 	if err != nil {
 		return nil, &XAttrError{"getxattr", path, name, err}
 	}
-	buf := make([]byte, size)
-	// Read into buffer of that size.
-	read, err := getxattr(path, name, &buf[0], size, 0, 0)
-	if err != nil {
-		return nil, &XAttrError{"getxattr", path, name, err}
+	if size > 0 {
+		buf := make([]byte, size)
+		// Read into buffer of that size.
+		read, err := getxattr(path, name, &buf[0], size, 0, 0)
+		if err != nil {
+			return nil, &XAttrError{"getxattr", path, name, err}
+		}
+		return buf[:read], nil
 	}
-	return buf[:read], nil
+	return []byte{}, nil
 }
 
-// Retrieves a list of names of extended attributes associated with the
-// given path in the file system.
+// Listxattr retrieves a list of names of extended attributes associated
+// with the given path in the file system.
 func Listxattr(path string) ([]string, error) {
 	// find size.
 	size, err := listxattr(path, nil, 0, 0)
 	if err != nil {
 		return nil, &XAttrError{"listxattr", path, "", err}
 	}
-	if size == 0 {
-		return []string{}, nil
-	}
+	if size > 0 {
 
-	buf := make([]byte, size)
-	// Read into buffer of that size.
-	read, err := listxattr(path, &buf[0], size, 0)
-	if err != nil {
-		return nil, &XAttrError{"listxattr", path, "", err}
+		buf := make([]byte, size)
+		// Read into buffer of that size.
+		read, err := listxattr(path, &buf[0], size, 0)
+		if err != nil {
+			return nil, &XAttrError{"listxattr", path, "", err}
+		}
+		return nullTermToStrings(buf[:read]), nil
 	}
-	return nullTermToStrings(buf[:read]), nil
+	return []string{}, nil
 }
 
-// Associates name and data together as an attribute of path.
+// Setxattr associates name and data together as an attribute of path.
 func Setxattr(path, name string, data []byte) error {
 	if err := setxattr(path, name, &data[0], len(data), 0, 0); err != nil {
 		return &XAttrError{"setxattr", path, name, err}
@@ -47,7 +50,7 @@ func Setxattr(path, name string, data []byte) error {
 	return nil
 }
 
-// Remove the attribute.
+// Removexattr removes the attribute associated with the given path.
 func Removexattr(path, name string) error {
 	if err := removexattr(path, name, 0); err != nil {
 		return &XAttrError{"removexattr", path, name, err}

vendor/src/github.com/pkg/xattr/xattr_freebsd.go

@@ -10,40 +10,46 @@ const (
 	EXTATTR_NAMESPACE_USER = 1
 )
 
-// Retrieve extended attribute data associated with path.
+// Getxattr retrieves extended attribute data associated with path.
 func Getxattr(path, name string) ([]byte, error) {
 	// find size.
 	size, err := extattr_get_file(path, EXTATTR_NAMESPACE_USER, name, nil, 0)
 	if err != nil {
 		return nil, &XAttrError{"extattr_get_file", path, name, err}
 	}
-	buf := make([]byte, size)
-	// Read into buffer of that size.
-	read, err := extattr_get_file(path, EXTATTR_NAMESPACE_USER, name, &buf[0], size)
-	if err != nil {
-		return nil, &XAttrError{"extattr_get_file", path, name, err}
+	if size > 0 {
+		buf := make([]byte, size)
+		// Read into buffer of that size.
+		read, err := extattr_get_file(path, EXTATTR_NAMESPACE_USER, name, &buf[0], size)
+		if err != nil {
+			return nil, &XAttrError{"extattr_get_file", path, name, err}
+		}
+		return buf[:read], nil
 	}
-	return buf[:read], nil
+	return []byte{}, nil
 }
 
-// Retrieves a list of names of extended attributes associated with the
-// given path in the file system.
+// Listxattr retrieves a list of names of extended attributes associated
+// with the given path in the file system.
 func Listxattr(path string) ([]string, error) {
 	// find size.
 	size, err := extattr_list_file(path, EXTATTR_NAMESPACE_USER, nil, 0)
 	if err != nil {
 		return nil, &XAttrError{"extattr_list_file", path, "", err}
 	}
-	buf := make([]byte, size)
-	// Read into buffer of that size.
-	read, err := extattr_list_file(path, EXTATTR_NAMESPACE_USER, &buf[0], size)
-	if err != nil {
-		return nil, &XAttrError{"extattr_list_file", path, "", err}
+	if size > 0 {
+		buf := make([]byte, size)
+		// Read into buffer of that size.
+		read, err := extattr_list_file(path, EXTATTR_NAMESPACE_USER, &buf[0], size)
+		if err != nil {
+			return nil, &XAttrError{"extattr_list_file", path, "", err}
+		}
+		return attrListToStrings(buf[:read]), nil
 	}
-	return attrListToStrings(buf[:read]), nil
+	return []string{}, nil
 }
 
-// Associates name and data together as an attribute of path.
+// Setxattr associates name and data together as an attribute of path.
 func Setxattr(path, name string, data []byte) error {
 	written, err := extattr_set_file(path, EXTATTR_NAMESPACE_USER, name, &data[0], len(data))
 	if err != nil {
@@ -55,7 +61,7 @@ func Setxattr(path, name string, data []byte) error {
 	return nil
 }
 
-// Remove the attribute.
+// Removexattr removes the attribute associated with the given path.
 func Removexattr(path, name string) error {
 	if err := extattr_delete_file(path, EXTATTR_NAMESPACE_USER, name); err != nil {
 		return &XAttrError{"extattr_delete_file", path, name, err}
@@ -63,7 +69,7 @@ func Removexattr(path, name string) error {
 	return nil
 }
 
-// Convert a sequnce of attribute name entries to a []string.
+// attrListToStrings converts a sequnce of attribute name entries to a []string.
 // Each entry consists of a single byte containing the length
 // of the attribute name, followed by the attribute name.
 // The name is _not_ terminated by NUL.

vendor/src/github.com/pkg/xattr/xattr_linux.go

@@ -4,40 +4,46 @@ package xattr
 
 import "syscall"
 
-// Retrieve extended attribute data associated with path.
+// Getxattr retrieves extended attribute data associated with path.
 func Getxattr(path, name string) ([]byte, error) {
 	// find size.
 	size, err := syscall.Getxattr(path, name, nil)
 	if err != nil {
 		return nil, &XAttrError{"getxattr", path, name, err}
 	}
-	data := make([]byte, size)
-	// Read into buffer of that size.
-	read, err := syscall.Getxattr(path, name, data)
-	if err != nil {
-		return nil, &XAttrError{"getxattr", path, name, err}
+	if size > 0 {
+		data := make([]byte, size)
+		// Read into buffer of that size.
+		read, err := syscall.Getxattr(path, name, data)
+		if err != nil {
+			return nil, &XAttrError{"getxattr", path, name, err}
+		}
+		return data[:read], nil
 	}
-	return data[:read], nil
+	return []byte{}, nil
 }
 
-// Retrieves a list of names of extended attributes associated with the
-// given path in the file system.
+// Listxattr retrieves a list of names of extended attributes associated
+// with the given path in the file system.
 func Listxattr(path string) ([]string, error) {
 	// find size.
 	size, err := syscall.Listxattr(path, nil)
 	if err != nil {
 		return nil, &XAttrError{"listxattr", path, "", err}
 	}
-	buf := make([]byte, size)
-	// Read into buffer of that size.
-	read, err := syscall.Listxattr(path, buf)
-	if err != nil {
-		return nil, &XAttrError{"listxattr", path, "", err}
+	if size > 0 {
+		buf := make([]byte, size)
+		// Read into buffer of that size.
+		read, err := syscall.Listxattr(path, buf)
+		if err != nil {
+			return nil, &XAttrError{"listxattr", path, "", err}
+		}
+		return nullTermToStrings(buf[:read]), nil
 	}
-	return nullTermToStrings(buf[:read]), nil
+	return []string{}, nil
 }
 
-// Associates name and data together as an attribute of path.
+// Setxattr associates name and data together as an attribute of path.
 func Setxattr(path, name string, data []byte) error {
 	if err := syscall.Setxattr(path, name, data, 0); err != nil {
 		return &XAttrError{"setxattr", path, name, err}
@@ -45,7 +51,8 @@ func Setxattr(path, name string, data []byte) error {
 	return nil
 }
 
-// Remove the attribute.
+// Removexattr removes the attribute associated
+// with the given path.
 func Removexattr(path, name string) error {
 	if err := syscall.Removexattr(path, name); err != nil {
 		return &XAttrError{"removexattr", path, name, err}