[PATCH v2] support: Don't fail on fchown when spawning sgid processes

[Siddhesh Poyarekar <siddhesh@sourceware.org>]

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: Frederic Berat <fberat@redhat.com>
Signed-off-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
---
 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..3881e3610a 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);
+
+  int chowned = 0;
+  TEST_VERIFY ((chowned = fchown (outfd, getuid (), gid)) == 0
+	       || errno == EPERM);
   if (support_record_failure_is_failed ())
     goto err;
+  else if (chowned != 0)
+    {
+      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;
 }
-- 
2.40.1