1 files changed, 97 insertions, 0 deletions
diff --git a/sysdeps/unix/sysv/linux/tst-ofdlocks-compat.c b/sysdeps/unix/sysv/linux/tst-ofdlocks-compat.c
new file mode 100644
index 0000000000..aaf65af0db
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/tst-ofdlocks-compat.c
@@ -0,0 +1,97 @@
+/* Check non representable OFD locks regions in non-LFS mode for compat
+   mode (BZ #20251)
+   Copyright (C) 2018 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or
+   modify it under the terms of the GNU General Public License
+   as published by the Free Software Foundation; either version 2
+   of the License, or (at your option) any later version.
+
+   This program 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 General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include <unistd.h>
+#include <fcntl.h>
+#include <stdint.h>
+#include <errno.h>
+
+#include <support/temp_file.h>
+#include <support/check.h>
+
+#include <shlib-compat.h>
+#if TEST_COMPAT (libc, GLIBC_2_0, GLIBC_2_28)
+compat_symbol_reference (libc, fcntl, fcntl, GLIBC_2_0);
+
+static char *temp_filename;
+static int temp_fd;
+
+static void
+do_prepare (int argc, char **argv)
+{
+  temp_fd = create_temp_file ("tst-ofdlocks-compat.", &temp_filename);
+  TEST_VERIFY_EXIT (temp_fd != -1);
+}
+
+#define PREPARE do_prepare
+
+/* Linux between 4.13 and 4.15 return EOVERFLOW for LFS OFD locks usage
+   in compat mode (non-LFS ABI running on a LFS default kernel, such as
+   i386 on a x86_64 kernel or s390-32 on a s390-64 kernel) [1].  This is
+   a kernel issue because __NR_fcntl64 is the expected way to use OFD locks
+   (used on GLIBC for both fcntl and fcntl64).
+
+   [1] https://sourceware.org/ml/libc-alpha/2018-07/msg00243.html  */
+
+static int
+do_test (void)
+{
+  /* The compat fcntl version for architectures which support non-LFS
+     operations does not wrap the flock OFD argument, so the struct is passed
+     unmodified to kernel.  It means no EOVERFLOW is returned, so operations
+     with LFS should not incur in failure.  */
+
+  struct flock64 lck64 = {
+    .l_type   = F_WRLCK,
+    .l_whence = SEEK_SET,
+    .l_start  = (off64_t)INT32_MAX + 1024,
+    .l_len    = 1024,
+  };
+  int ret = fcntl (temp_fd, F_OFD_SETLKW, &lck64);
+  if (ret == -1 && errno == EINVAL)
+    /* OFD locks are only available on Linux 3.15.  */
+    FAIL_UNSUPPORTED ("fcntl (F_OFD_SETLKW) not supported");
+
+  TEST_VERIFY_EXIT (ret == 0);
+
+  /* Open file description locks placed through the same open file description
+     (either by same file descriptor or a duplicated one created by fork,
+     dup, fcntl F_DUPFD, etc.) overwrites then old lock.  To force a
+     conflicting lock combination, it creates a new file descriptor.  */
+  int fd = open64 (temp_filename, O_RDWR, 0666);
+  TEST_VERIFY_EXIT (fd != -1);
+
+  struct flock64 lck = {
+    .l_type   = F_WRLCK,
+    .l_whence = SEEK_SET,
+    .l_start  = INT32_MAX - 1024,
+    .l_len    = 4 * 1024,
+  };
+  TEST_VERIFY (fcntl (fd, F_OFD_GETLK, &lck) == 0);
+
+  return 0;
+}
+#else
+static int
+do_test (void)
+{
+  return 77;
+}
+#endif
+
+#include <support/test-driver.c>