sysconf: Fix missing definition of UIO_MAXIOV on Linux [BZ #22321]

After commit 37f802f86400684c8d13403958b2c598721d6360 (Remove
__need_IOV_MAX and __need_FOPEN_MAX), UIO_MAXIOV is no longer supplied
(indirectly) through <bits/stdio_lim.h>, so sysdeps/posix/sysconf.c no
longer sees the definition.

3 files changed, 71 insertions, 1 deletions

diff --git a/sysdeps/unix/sysv/linux/Makefile b/sysdeps/unix/sysv/linux/Makefile
index 30bd167bae..0c8a009b5e 100644
--- a/sysdeps/unix/sysv/linux/Makefile
+++ b/sysdeps/unix/sysv/linux/Makefile
@@ -50,7 +50,7 @@ sysdep_headers += sys/mount.h sys/acct.h sys/sysctl.h \
 		  bits/siginfo-arch.h bits/siginfo-consts-arch.h
 
 tests += tst-clone tst-clone2 tst-clone3 tst-fanotify tst-personality \
-	 tst-quota tst-sync_file_range test-errno-linux
+	 tst-quota tst-sync_file_range test-errno-linux tst-sysconf-iov_max
 
 # Generate the list of SYS_* macros for the system calls (__NR_*
 # macros).  The file syscall-names.list contains all possible system
@@ -95,6 +95,9 @@ $(objpfx)tst-syscall-list.out: \
   $(objpfx)tst-syscall-list-sys.list
 	$(BASH) $^ $(AWK) > $@; $(evaluate-test)
 
+# Separate object file for access to the constant from the UAPI header.
+$(objpfx)tst-sysconf-iov_max: $(objpfx)tst-sysconf-iov_max-uapi.o
+
 endif # $(subdir) == misc
 
 ifeq ($(subdir),time)
diff --git a/sysdeps/unix/sysv/linux/tst-sysconf-iov_max-uapi.c b/sysdeps/unix/sysv/linux/tst-sysconf-iov_max-uapi.c
new file mode 100644
index 0000000000..1240b846e6
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/tst-sysconf-iov_max-uapi.c
@@ -0,0 +1,27 @@
+/* Check IOV_MAX definition: Helper function to capture UAPI header value.
+   Copyright (C) 2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+/* Use a separate function to avoid header compatibility issues.  */
+
+#include <linux/uio.h>
+
+long
+uio_maxiov_value (void)
+{
+  return UIO_MAXIOV;
+}
diff --git a/sysdeps/unix/sysv/linux/tst-sysconf-iov_max.c b/sysdeps/unix/sysv/linux/tst-sysconf-iov_max.c
new file mode 100644
index 0000000000..dfdf3da484
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/tst-sysconf-iov_max.c
@@ -0,0 +1,40 @@
+/* Check IOV_MAX definition for consistency (bug 22321).
+   Copyright (C) 2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+/* Defined in tst-sysconf-iov_max-uapi.c.  */
+long uio_maxiov_value (void);
+
+
+#include <limits.h>
+#include <support/check.h>
+#include <sys/uio.h>
+#include <unistd.h>
+
+static int
+do_test (void)
+{
+  TEST_VERIFY (_XOPEN_IOV_MAX == 16); /* Value required by POSIX.  */
+  TEST_VERIFY (uio_maxiov_value () >= _XOPEN_IOV_MAX);
+  TEST_VERIFY (IOV_MAX == uio_maxiov_value ());
+  TEST_VERIFY (UIO_MAXIOV == uio_maxiov_value ());
+  TEST_VERIFY (sysconf (_SC_UIO_MAXIOV) == uio_maxiov_value ());
+  TEST_VERIFY (sysconf (_SC_IOV_MAX) == uio_maxiov_value ());
+  return 0;
+}
+
+#include <support/test-driver.c>