[v7,4/5] linux: Add tst-mount to check for Linux new mount API

  The new mount API was added on Linux 5.2 with six new syscalls:
fsopen, fsconfig, fsmount, move_mount, fspick, and open_tree.

The new test verifies minimal functionality along with error paths
for specific arguments and their corner cases.

Checked on x86_64-linux-gnu.
---
 sysdeps/unix/sysv/linux/Makefile    |  1 +
 sysdeps/unix/sysv/linux/tst-mount.c | 95 +++++++++++++++++++++++++++++
 2 files changed, 96 insertions(+)
 create mode 100644 sysdeps/unix/sysv/linux/tst-mount.c
  

On 6/24/22 15:59, Adhemerval Zanella wrote:
> The new mount API was added on Linux 5.2 with six new syscalls:
> fsopen, fsconfig, fsmount, move_mount, fspick, and open_tree.
> 
> The new test verifies minimal functionality along with error paths
> for specific arguments and their corner cases.
> 
> Checked on x86_64-linux-gnu.

LGTM. Exercises error paths.

Reviewed-by: Carlos O'Donell <carlos@redhat.com>

> ---
>  sysdeps/unix/sysv/linux/Makefile    |  1 +
>  sysdeps/unix/sysv/linux/tst-mount.c | 95 +++++++++++++++++++++++++++++
>  2 files changed, 96 insertions(+)
>  create mode 100644 sysdeps/unix/sysv/linux/tst-mount.c
> 
> diff --git a/sysdeps/unix/sysv/linux/Makefile b/sysdeps/unix/sysv/linux/Makefile
> index 7ffcf7ed83..2ccc92b6b8 100644
> --- a/sysdeps/unix/sysv/linux/Makefile
> +++ b/sysdeps/unix/sysv/linux/Makefile
> @@ -130,6 +130,7 @@ tests += tst-clone tst-clone2 tst-clone3 tst-fanotify tst-personality \
>    tst-getauxval \
>    tst-pidfd \
>    tst-process_mrelease \
> +  tst-mount \

OK.

>    # tests
>  
>  # process_madvise requires CAP_SYS_ADMIN.
> diff --git a/sysdeps/unix/sysv/linux/tst-mount.c b/sysdeps/unix/sysv/linux/tst-mount.c
> new file mode 100644
> index 0000000000..12a665f950
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/tst-mount.c
> @@ -0,0 +1,95 @@
> +/* Basic tests for the new Linux API added on Linux 5.2.
> +   Copyright (C) 2022 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; see the file COPYING.LIB.  If
> +   not, see <https://www.gnu.org/licenses/>.  */
> +
> +#include <errno.h>
> +#include <support/check.h>
> +#include <support/xunistd.h>
> +#include <support/namespace.h>
> +#include <sys/wait.h>
> +#include <sys/mount.h>
> +
> +static void
> +subprocess (void)
> +{
> +  int r = fsopen ("it_should_be_not_a_valid_mount", 0);
> +  TEST_VERIFY_EXIT (r == -1);
> +  if (errno == ENOSYS)
> +    FAIL_UNSUPPORTED ("kernel does not support new mount API, skipping test");
> +  TEST_COMPARE (errno, ENODEV);

OK. Invalid mount path.

> +
> +  int fd = fsopen ("tmpfs", FSOPEN_CLOEXEC);
> +  TEST_VERIFY (fd != -1);
> +
> +  TEST_COMPARE (fsconfig (-1, FSCONFIG_SET_STRING, "size", "2048", 0), -1);
> +  TEST_COMPARE (errno, EINVAL);
> +
> +  {
> +    int r = fsconfig (fd, FSCONFIG_SET_STRING, "size", "2048", 0);
> +    TEST_VERIFY (r != -1);
> +    r = fsconfig (fd, FSCONFIG_CMD_CREATE, NULL, NULL, 0);
> +    TEST_VERIFY (r != -1);
> +  }
> +
> +  TEST_COMPARE (fsmount (-1, FSMOUNT_CLOEXEC, MOUNT_ATTR_NODEV), -1);
> +  TEST_COMPARE (errno, EBADF);

OK. -1 is an invalid fd.

> +
> +  int mfd = fsmount (fd, FSMOUNT_CLOEXEC, MOUNT_ATTR_NODEV);
> +  TEST_VERIFY (mfd != -1);
> +
> +  TEST_COMPARE (move_mount (-1, "", AT_FDCWD, "/tmp", 0), -1);
> +  TEST_COMPARE (errno, ENOENT);
> +  {
> +    int r = move_mount (mfd, "", AT_FDCWD, "/tmp", MOVE_MOUNT_F_EMPTY_PATH);
> +    TEST_VERIFY (r != -1);
> +  }
> +
> +  TEST_COMPARE (fspick (AT_FDCWD, "", 0), -1);
> +  TEST_COMPARE (errno, ENOENT);
> +  {
> +    int pfd = fspick (AT_FDCWD, "/tmp", FSPICK_CLOEXEC);
> +    TEST_VERIFY (pfd != -1);
> +  }

OK.

> +
> +  TEST_COMPARE (open_tree (AT_FDCWD, "", 0), -1);
> +  TEST_COMPARE (errno, ENOENT);
> +  {
> +    int fd_tree = open_tree (AT_FDCWD, "/tmp",
> +			     OPEN_TREE_CLONE | OPEN_TREE_CLOEXEC);
> +    TEST_VERIFY (fd_tree != -1);

OK.

> +  }
> +
> +  _exit (0);
> +}
> +
> +static int
> +do_test (void)
> +{
> +  support_become_root ();
> +
> +  pid_t pid = xfork ();
> +  if (pid == 0)
> +    subprocess ();
> +
> +  int status;
> +  xwaitpid (pid, &status, 0);
> +  TEST_VERIFY (WIFEXITED (status));
> +
> +  return 0;
> +}
> +
> +#include <support/test-driver.c>