[glibc] support: Don't fail on fchown when spawning sgid processes

[Siddhesh Poyarekar <siddhesh@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=6286cca2cb8389dcffec39238a8bf15ffea96396

commit 6286cca2cb8389dcffec39238a8bf15ffea96396
Author: Siddhesh Poyarekar <siddhesh@sourceware.org>
Date:   Thu Jun 1 07:23:15 2023 -0400

    support: Don't fail on fchown when spawning sgid processes
    
    In some cases (e.g. when podman creates user containers), the only other
    group assigned to the executing user is nobody and fchown fails with it
    because the group is not mapped.  Do not fail the test in this case,
    instead exit as unsupported.
    
    Reported-by: Frédéric Bérat <fberat@redhat.com>
    Tested-by: Frédéric Bérat <fberat@redhat.com>
    Signed-off-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
    Reviewed-by: Carlos O'Donell <carlos@redhat.com>

Diff:
---
 support/support_capture_subprocess.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/support/support_capture_subprocess.c b/support/support_capture_subprocess.c
index bae7d5fb20..2a8d37b284 100644
--- a/support/support_capture_subprocess.c
+++ b/support/support_capture_subprocess.c
@@ -153,9 +153,18 @@ copy_and_spawn_sgid (char *child_id, gid_t gid)
 	  p += wrcount;
 	}
     }
-  TEST_VERIFY (fchown (outfd, getuid (), gid) == 0);
+
+  bool chowned = false;
+  TEST_VERIFY ((chowned = fchown (outfd, getuid (), gid) == 0)
+	       || errno == EPERM);
   if (support_record_failure_is_failed ())
     goto err;
+  else if (!chowned)
+    {
+      ret = 77;
+      goto err;
+    }
+
   TEST_VERIFY (fchmod (outfd, 02750) == 0);
   if (support_record_failure_is_failed ())
     goto err;
@@ -192,8 +201,10 @@ err:
       free (dirname);
     }
 
+  if (ret == 77)
+    FAIL_UNSUPPORTED ("Failed to make sgid executable for test\n");
   if (ret != 0)
-    FAIL_EXIT1("Failed to make sgid executable for test\n");
+    FAIL_EXIT1 ("Failed to make sgid executable for test\n");
 
   return status;
 }