Issue #12841: Fix tarfile extraction of non-existent uids/gids.

tarfile unnecessarily checked the existence of numerical user and group ids on
extraction. If one of them did not exist the respective id of the current user
(i.e. root) was used for the file and ownership information was lost. (Patch
by Sebastien Luttringer)

1 files changed, 2 insertions, 8 deletions

diff --git a/Lib/tarfile.py b/Lib/tarfile.py
index 3d52a81b9e..1ece716197 100644
--- a/Lib/tarfile.py
+++ b/Lib/tarfile.py
@@ -2368,17 +2368,11 @@ class TarFile(object):
             try:
                 g = grp.getgrnam(tarinfo.gname)[2]
             except KeyError:
-                try:
-                    g = grp.getgrgid(tarinfo.gid)[2]
-                except KeyError:
-                    g = os.getgid()
+                g = tarinfo.gid
             try:
                 u = pwd.getpwnam(tarinfo.uname)[2]
             except KeyError:
-                try:
-                    u = pwd.getpwuid(tarinfo.uid)[2]
-                except KeyError:
-                    u = os.getuid()
+                u = tarinfo.uid
             try:
                 if tarinfo.issym() and hasattr(os, "lchown"):
                     os.lchown(targetpath, u, g)