stdlib/tst-secure-getenv: handle >64 groups

This test would fail unnecessarily if the user running it had more than
64 groups since getgroups returns EINVAL if the size provided is less
than the number of supplementary group IDs. Instead dynamically
determine the number of supplementary groups the user has.

1 files changed, 15 insertions, 4 deletions

diff --git a/stdlib/tst-secure-getenv.c b/stdlib/tst-secure-getenv.c
index 74580b8..94de199 100644
--- a/stdlib/tst-secure-getenv.c
+++ b/stdlib/tst-secure-getenv.c
@@ -41,8 +41,14 @@ static char MAGIC_ARGUMENT[] = "run-actual-test";
 static gid_t
 choose_gid (void)
 {
-  const int count = 64;
-  gid_t groups[count];
+  int count = getgroups (0, NULL);
+  if (count < 0)
+    {
+      printf ("getgroups: %m\n");
+      exit (1);
+    }
+  gid_t *groups;
+  groups = xcalloc (count, sizeof (*groups));
   int ret = getgroups (count, groups);
   if (ret < 0)
     {
@@ -50,12 +56,17 @@ choose_gid (void)
       exit (1);
     }
   gid_t current = getgid ();
+  gid_t not_current = 0;
   for (int i = 0; i < ret; ++i)
     {
       if (groups[i] != current)
-	return groups[i];
+        {
+          not_current = groups[i];
+          break;
+        }
     }
-  return 0;
+  free (groups);
+  return not_current;
 }