Cygwin: newgrp: fix invalid usage of argv

Fix an error message accessing argv[1] even after it has been
potentially moved.  Print group name from group DB instead.

Fixes: 8bd56ec873453 ("Cygwin: newgrp: first full version")
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>

diff --git a/winsup/utils/newgrp.c b/winsup/utils/newgrp.c
index 88586352e108f41bbc991e522be352ab13c98d98..e312a3c51d38d8db3bc71e307add0f07a46c4075 100644 (file)
--- a/winsup/utils/newgrp.c
+++ b/winsup/utils/newgrp.c
@@ -160,6 +160,7 @@ main (int argc, const char **argv)
   if (argv[1] == NULL)
     {
       gid = pw->pw_gid;
+      gr = getgrgid (gid);
     }
   else
     {
@@ -179,7 +180,7 @@ main (int argc, const char **argv)
   if (setgid (gid) != 0)
     {
       fprintf (stderr, "%s: can't switch primary group to '%s'\n",
-              program_invocation_short_name, argv[1]);
+              program_invocation_short_name, gr->gr_name);
       return 2;
     }