Fixed all known issues with copying files via the Finder.

For #125.

docs/semantics.md

@@ -300,7 +300,7 @@ look up child inodes. Unlike file inodes:
 
 *   gcsfuse does not keep track of modification time for
     directories. There are no guarantees for the contents of `stat::st_mtime`
-    or equivalent.
+    or equivalent or the behavior of `utimes(2)` and similar.
 
 *   There are no guarantees about `stat::st_nlink`.
 
@@ -372,7 +372,8 @@ By default, all inodes in a gcsfuse file system show up as being owned by the
 UID and GID of the gcsfuse process itself, i.e. the user who mounted the file
 system. All files have permission bits `0644`, and all directories have
 permission bits `0755` (but see below for issues with use by other users).
-Changing permission bits is not supported.
+Changing inode mode (using `chmod(2)` or similar) is unsupported, and changes
+are silently ignored.
 
 These defaults can be overriden with the `--uid`, `--gid`, `--file-mode`, and
 `--dir-mode` flags.

internal/fs/fs.go

@@ -952,38 +952,27 @@ func (fs *fileSystem) SetInodeAttributes(
 
 	in.Lock()
 	defer in.Unlock()
+	file, isFile := in.(*inode.FileInode)
 
-	// We don't support changing non-files.
-	file, ok := in.(*inode.FileInode)
-	if !ok {
-		err = fuse.ENOSYS
-		return
-	}
-
-	// Set the mtime, if requested.
-	if op.Mtime != nil {
+	// Set file mtimes.
+	if isFile && op.Mtime != nil {
 		err = file.SetMtime(ctx, *op.Mtime)
 		if err != nil {
 			err = fmt.Errorf("SetMtime: %v", err)
 			return
 		}
 	}
 
-	// Set the size, if specified.
-	if op.Size != nil {
+	// Truncate files.
+	if isFile && op.Size != nil {
 		err = file.Truncate(ctx, int64(*op.Size))
 		if err != nil {
 			err = fmt.Errorf("Truncate: %v", err)
 			return
 		}
 	}
 
-	// We don't support setting mode. (We silently ignore atime updates, as per
-	// docs/semantics.md.)
-	if op.Mode != nil {
-		err = fuse.ENOSYS
-		return
-	}
+	// We silently ignore updates to mode and atime.
 
 	// Fill in the response.
 	op.Attributes, op.AttributesExpiration, err = fs.getAttributes(ctx, in)

internal/fs/local_modifications_test.go

@@ -1161,6 +1161,35 @@ func (t *DirectoryTest) CreateHardLink() {
 	ExpectThat(err, Error(HasSubstr("not implemented")))
 }
 
+func (t *DirectoryTest) Chmod() {
+	var err error
+
+	// Create a directory.
+	p := path.Join(t.mfs.Dir(), "foo")
+	err = os.Mkdir(p, 0700)
+	AssertEq(nil, err)
+
+	// Attempt to chmod it. Chmod should succeed even though we don't do anything
+	// useful. The OS X Finder otherwise complains to the user when copying in a
+	// file.
+	err = os.Chmod(p, 0777)
+	ExpectEq(nil, err)
+}
+
+func (t *DirectoryTest) Chtimes() {
+	var err error
+
+	// Create a directory.
+	p := path.Join(t.mfs.Dir(), "foo")
+	err = os.Mkdir(p, 0700)
+	AssertEq(nil, err)
+
+	// Chtimes should succeed even though we don't do anything useful. The OS X
+	// Finder otherwise complains to the user when copying in a directory.
+	err = os.Chtimes(p, time.Now(), time.Now())
+	ExpectEq(nil, err)
+}
+
 ////////////////////////////////////////////////////////////////////////
 // File interaction
 ////////////////////////////////////////////////////////////////////////
@@ -1680,15 +1709,15 @@ func (t *FileTest) Chmod() {
 	var err error
 
 	// Write a file.
-	fileName := path.Join(t.mfs.Dir(), "foo")
-	err = ioutil.WriteFile(fileName, []byte(""), 0700)
+	p := path.Join(t.mfs.Dir(), "foo")
+	err = ioutil.WriteFile(p, []byte(""), 0700)
 	AssertEq(nil, err)
 
-	// Attempt to chmod it. We don't support doing so.
-	err = os.Chmod(fileName, 0777)
-
-	AssertNe(nil, err)
-	ExpectThat(err, Error(HasSubstr("not implemented")))
+	// Attempt to chmod it. Chmod should succeed even though we don't do anything
+	// useful. The OS X Finder otherwise complains to the user when copying in a
+	// file.
+	err = os.Chmod(p, 0777)
+	ExpectEq(nil, err)
 }
 
 func (t *FileTest) Chtimes_InactiveFile() {
@@ -1784,19 +1813,6 @@ func (t *FileTest) Chtimes_OpenFile_Dirty() {
 	ExpectThat(fi.ModTime(), timeutil.TimeEq(newMtime))
 }
 
-func (t *FileTest) Chtimes_Directory() {
-	var err error
-
-	// Create a directory.
-	p := path.Join(t.mfs.Dir(), "foo")
-	err = os.Mkdir(p, 0700)
-	AssertEq(nil, err)
-
-	// Chtimes should fail; we don't support it for directories.
-	err = os.Chtimes(p, time.Now(), time.Now())
-	ExpectThat(err, Error(HasSubstr("not implemented")))
-}
-
 func (t *FileTest) Sync_Dirty() {
 	var err error
 	var n int