n

Change-Id: Iaab5d235f7f05d40ec3dee23256c5866d4a99aa4

Author: qiulaidongfeng

doc/next/6-stdlib/99-minor/archive/tar/50102.md

@@ -1 +1,3 @@
-If the argument to [`tar.FileInfoHeader`](/archive/tar#FileInfoHeader) implements the new [`tar.FileInfoNames`](/archive/tar#FileInfoNames) interface, then the interface methods will be used to set the Uname/Gname of the file header. This allows applications to override the default Uname/Gname resolution.
+If the argument to [`FileInfoHeader`](/archive/tar#FileInfoHeader) implements the new [`FileInfoNames`](/archive/tar#FileInfoNames) interface, 
+then the interface methods will be used to set the Uname/Gname of the file header. 
+This allows applications to override the system-dependent Uname/Gname lookup.

src/archive/tar/common.go

@@ -641,7 +641,7 @@ const (
 // to provide the full path name of the file.
 //
 // If fi implements [FileInfoNames]
-// the Gname and Uname of the header are
+// Header.Gname and Header.Uname
 // provided by the methods of the interface.
 func FileInfoHeader(fi fs.FileInfo, link string) (*Header, error) {
 	if fi == nil {
@@ -734,9 +734,9 @@ func FileInfoHeader(fi fs.FileInfo, link string) (*Header, error) {
 	return h, nil
 }
 
-// FileInfoNames extends [fs.FileInfo]
+// FileInfoNames extends [fs.FileInfo].
 // Passing an instance of this to [FileInfoHeader] permits the caller
-// to control Gname and Uname set.
+// to avoid asystem-dependent name lookup by specifying the Uname and Gname directly.
 type FileInfoNames interface {
 	fs.FileInfo
 	// Uname should give a user name.

src/archive/tar/stat_unix.go

@@ -28,6 +28,9 @@ func statUnix(fi fs.FileInfo, h *Header, doNameLookups bool) error {
 	if !ok {
 		return nil
 	}
+
+	h.Uid = int(sys.Uid)
+	h.Gid = int(sys.Gid)
 	if doNameLookups {
 		// Best effort at populating Uname and Gname.
 		// The os/user functions may fail for any number of reasons
@@ -45,9 +48,6 @@ func statUnix(fi fs.FileInfo, h *Header, doNameLookups bool) error {
 			groupMap.Store(h.Gid, h.Gname)
 		}
 	}
-
-	h.Uid = int(sys.Uid)
-	h.Gid = int(sys.Gid)
 	h.AccessTime = statAtime(sys)
 	h.ChangeTime = statCtime(sys)