When running the gnulib unit tests in sed-4.5.48-58eb on Cygwin, I see
a failure of the select tests:
failed (invalid fd among rfds)
failed (invalid fd among wfds)
failed (invalid fd among xfds)
The sed-4.5.48-58eb snapshot is built with an Autoconf snapshot that
contains a bug: it reports
checking whether we are cross compiling... yes
(instead of 'no'), and as a consequence
checking whether select detects invalid fds... guessing no
(instead of 'yes'), leading to REPLACE_SELECT=1, and the gnulib
override in select.c sets errno to EINVAL, not EBADF, when
invoked with fd = 99 and nfds = 100 (apparently unlike the
original Cygwin select() function - cf. the comment in test-select.h
function test_bad_nfd).
This patch fixes the test in gnulib. The bug in Autoconf is separate.
2018-12-13 Bruno Haible <br...@clisp.org>
select tests: Avoid test failure on Cygwin.
* tests/test-select.h (test_bad_fd): Use an fd < FD_SETSIZE.
diff --git a/tests/test-select.h b/tests/test-select.h
index eae26b0..b0f17f3 100644
--- a/tests/test-select.h
+++ b/tests/test-select.h
@@ -242,9 +242,11 @@ test_bad_nfd (select_fn my_select)
/* Can't test FD_SETSIZE + 1 for EINVAL, since some systems allow
dynamically larger set size by redefining FD_SETSIZE anywhere up
to the actual maximum fd. */
- /* if (do_select_bad_nfd_nowait (FD_SETSIZE + 1, my_select) != -1 */
- /* || errno != EINVAL) */
- /* failed ("invalid errno after bogus nfds"); */
+#if 0
+ if (do_select_bad_nfd_nowait (FD_SETSIZE + 1, my_select) != -1
+ || errno != EINVAL)
+ failed ("invalid errno after bogus nfds");
+#endif
}
/* Test select(2) on invalid file descriptors. */
@@ -294,6 +296,11 @@ test_bad_fd (select_fn my_select)
# else
fd = 99;
# endif
+ /* Even on the best POSIX compliant platforms, values of fd >= FD_SETSIZE
+ require an nfds argument that is > FD_SETSIZE and thus may lead to EINVAL,
+ not EBADF. */
+ if (fd >= FD_SETSIZE)
+ fd = FD_SETSIZE - 1;
close (fd);
if (do_select_bad_fd_nowait (fd, SEL_IN, my_select) == 0 || errno != EBADF)
