From d13f7aa0ae1ad6ec86d66953cc84851977580c8c Mon Sep 17 00:00:00 2001
From: Ian Lance Taylor <iant@golang.org>
Date: Wed, 9 Aug 2023 17:46:00 -0700
Subject: [PATCH] archive/tar: correct value passed to Uname method

For #50102

Change-Id: I28b5579611b07952b6379bc4603daf29a86a3be0
Reviewed-on: https://go-review.googlesource.com/c/go/+/518056
Auto-Submit: Ian Lance Taylor <iant@google.com>
Run-TryBot: Joseph Tsai <joetsai@digital-static.net>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Tianon Gravi (Andrew) <admwiggin@gmail.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Run-TryBot: Ian Lance Taylor <iant@google.com>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Reviewed-by: qiulaidongfeng <2645477756@qq.com>
Reviewed-by: Joseph Tsai <joetsai@digital-static.net>
---
 src/archive/tar/common.go   |  2 +-
 src/archive/tar/tar_test.go | 24 ++++++++++++++++++++++--
 2 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/src/archive/tar/common.go b/src/archive/tar/common.go
index f141548db8..8af17efa51 100644
--- a/src/archive/tar/common.go
+++ b/src/archive/tar/common.go
@@ -726,7 +726,7 @@ func FileInfoHeader(fi fs.FileInfo, link string) (*Header, error) {
 		if err != nil {
 			return nil, err
 		}
-		h.Uname, err = iface.Uname(h.Gid)
+		h.Uname, err = iface.Uname(h.Uid)
 		if err != nil {
 			return nil, err
 		}
diff --git a/src/archive/tar/tar_test.go b/src/archive/tar/tar_test.go
index 6bb27ec3e8..49d31bb757 100644
--- a/src/archive/tar/tar_test.go
+++ b/src/archive/tar/tar_test.go
@@ -849,6 +849,11 @@ func Benchmark(b *testing.B) {
 
 }
 
+const (
+	testUid = 10
+	testGid = 20
+)
+
 type fileInfoNames struct{}
 
 func (f *fileInfoNames) Name() string {
@@ -876,14 +881,29 @@ func (f *fileInfoNames) Sys() any {
 }
 
 func (f *fileInfoNames) Uname(uid int) (string, error) {
-	return "Uname", nil
+	if uid == testUid {
+		return "Uname", nil
+	}
+	return "", nil
 }
 
 func (f *fileInfoNames) Gname(gid int) (string, error) {
-	return "Gname", nil
+	if gid == testGid {
+		return "Gname", nil
+	}
+	return "", nil
 }
 
 func TestFileInfoHeaderUseFileInfoNames(t *testing.T) {
+	origLoadUidAndGid := loadUidAndGid
+	defer func() {
+		loadUidAndGid = origLoadUidAndGid
+	}()
+	loadUidAndGid = func(fi fs.FileInfo, uid, gid *int) {
+		*uid = testUid
+		*gid = testGid
+	}
+
 	info := &fileInfoNames{}
 	header, err := FileInfoHeader(info, "")
 	if err != nil {