vfs: use os package errors where possible

cmd/cmount/fs.go

@@ -632,24 +632,21 @@ func translateError(err error) (errc int) {
 	if err == nil {
 		return 0
 	}
-	cause := errors.Cause(err)
-	if mErr, ok := cause.(vfs.Error); ok {
-		switch mErr {
-		case vfs.OK:
-			return 0
-		case vfs.ENOENT:
-			return -fuse.ENOENT
-		case vfs.ENOTEMPTY:
-			return -fuse.ENOTEMPTY
-		case vfs.EEXIST:
-			return -fuse.EEXIST
-		case vfs.ESPIPE:
-			return -fuse.ESPIPE
-		case vfs.EBADF:
-			return -fuse.EBADF
-		case vfs.EROFS:
-			return -fuse.EROFS
-		}
+	switch errors.Cause(err) {
+	case vfs.OK:
+		return 0
+	case vfs.ENOENT:
+		return -fuse.ENOENT
+	case vfs.ENOTEMPTY:
+		return -fuse.ENOTEMPTY
+	case vfs.EEXIST:
+		return -fuse.EEXIST
+	case vfs.ESPIPE:
+		return -fuse.ESPIPE
+	case vfs.EBADF:
+		return -fuse.EBADF
+	case vfs.EROFS:
+		return -fuse.EROFS
 	}
 	fs.Errorf(nil, "IO error: %v", err)
 	return -fuse.EIO

cmd/mount/fs.go

@@ -68,24 +68,21 @@ func translateError(err error) error {
 	if err == nil {
 		return nil
 	}
-	cause := errors.Cause(err)
-	if mErr, ok := cause.(vfs.Error); ok {
-		switch mErr {
-		case vfs.OK:
-			return nil
-		case vfs.ENOENT:
-			return fuse.ENOENT
-		case vfs.ENOTEMPTY:
-			return fuse.Errno(syscall.ENOTEMPTY)
-		case vfs.EEXIST:
-			return fuse.EEXIST
-		case vfs.ESPIPE:
-			return fuse.Errno(syscall.ESPIPE)
-		case vfs.EBADF:
-			return fuse.Errno(syscall.EBADF)
-		case vfs.EROFS:
-			return fuse.Errno(syscall.EROFS)
-		}
+	switch errors.Cause(err) {
+	case vfs.OK:
+		return nil
+	case vfs.ENOENT:
+		return fuse.ENOENT
+	case vfs.ENOTEMPTY:
+		return fuse.Errno(syscall.ENOTEMPTY)
+	case vfs.EEXIST:
+		return fuse.EEXIST
+	case vfs.ESPIPE:
+		return fuse.Errno(syscall.ESPIPE)
+	case vfs.EBADF:
+		return fuse.Errno(syscall.EBADF)
+	case vfs.EROFS:
+		return fuse.Errno(syscall.EROFS)
 	}
 	return err
 }

vfs/errors.go

@@ -2,29 +2,34 @@
 
 package vfs
 
-import "fmt"
+import (
+	"fmt"
+	"os"
+)
 
 // Error describes low level errors in a cross platform way
 type Error byte
 
-// NB if changing errors translateError in cmd/mount/fs.go, cmd/cmount/fs.go, cmd/serve/webdav/webdav.go
+// NB if changing errors translateError in cmd/mount/fs.go, cmd/cmount/fs.go
 
 // Low level errors
 const (
 	OK Error = iota
-	ENOENT
 	ENOTEMPTY
-	EEXIST
 	ESPIPE
 	EBADF
 	EROFS
 )
 
+// Errors which have exact counterparts in os
+var (
+	ENOENT = os.ErrNotExist
+	EEXIST = os.ErrExist
+)
+
 var errorNames = []string{
 	OK:        "Success",
-	ENOENT:    "No such file or directory",
 	ENOTEMPTY: "Directory not empty",
-	EEXIST:    "File exists",
 	ESPIPE:    "Illegal seek",
 	EBADF:     "Bad file descriptor",
 	EROFS:     "Read only file system",