Re: Bug in test-fcntl.c

[Bruno Haible <bruno@clisp.org>]

Nicholas Gaya wrote:
> The process hierarchy starts with tclsh (MacPorts), then a bunch of layers of make and sh (from oath-toolkit's recursive `make check`), and finally the test-fcntl executable. I was using MacPorts' "trace mode", which seems to be responsible for the particularly high number of inherited open files, but without trace mode I still run into the issue; the returned fd is 11 in this case.

Thanks; that gives a hint also who is eating up the file descriptors 3 to 10.

> But I don't really want to focus on my specific use-case (for which I already have a workaround).  I think the patch is warranted just on the basis that it makes the test a bit more robust, with minimal drawbacks.

Yes. But I wanted to have a description of the cause, that I can include in
comments.

Done. Thanks for the report!


2021-05-14  Bruno Haible  <bruno@clisp.org>

	fcntl tests: Avoid failure in MacPorts.
	Reported by Nicholas Gaya <nicholasgaya@gmail.com> in
	<https://lists.gnu.org/archive/html/bug-gnulib/2021-05/msg00014.html>.
	* tests/test-fcntl.c (main): Close fd 10 before assuming that it is
	closed.
	* tests/test-execute-main.c: Update comment.

diff --git a/tests/test-execute-main.c b/tests/test-execute-main.c
index a6a9fe4..372ff1d 100644
--- a/tests/test-execute-main.c
+++ b/tests/test-execute-main.c
@@ -69,7 +69,8 @@ main (int argc, char *argv[])
          Such file descriptors have been seen:
            - with GNU make, when invoked as 'make -j N' with j > 1,
            - in some versions of the KDE desktop environment,
-           - on NetBSD.
+           - on NetBSD,
+           - in MacPorts with the "trace mode" enabled.
        */
       #if HAVE_CLOSE_RANGE
       if (close_range (3, 20 - 1, 0) < 0)
diff --git a/tests/test-fcntl.c b/tests/test-fcntl.c
index caf629d..cb834b4 100644
--- a/tests/test-fcntl.c
+++ b/tests/test-fcntl.c
@@ -415,6 +415,16 @@ main (int argc, char *argv[])
   ASSERT (close (fd) == 0);
   ASSERT (unlink (file) == 0);
 
+  /* Close file descriptors that may have been inherited from the parent
+     process and that would cause failures below.
+     Such file descriptors have been seen:
+       - with GNU make, when invoked as 'make -j N' with j > 1,
+       - in some versions of the KDE desktop environment,
+       - on NetBSD,
+       - in MacPorts with the "trace mode" enabled.
+   */
+  (void) close (10);
+
   /* Test whether F_DUPFD_CLOEXEC is effective.  */
   ASSERT (fcntl (1, F_DUPFD_CLOEXEC, 10) >= 0);
 #if defined _WIN32 && !defined __CYGWIN__