Re: [PATCH 2/3] Linux: unlockpt needs to fail with EINVAL, not ENOTTY (bug 26053)

[Adhemerval Zanella via Libc-alpha <libc-alpha@sourceware.org>]

On 05/08/2020 04:14, Florian Weimer via Libc-alpha wrote:
> The EINVAL error code is mandated by POSIX and documented in the
> manual.  Also clean up the unlockpt implementation a bit, assuming
> that TIOCSPTLCK is always defined.
> 
> Enhance login/tst-grantpt to cover unlockpt corner cases.

LGTM, thanks.

Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>

> ---
>  login/tst-grantpt.c                | 20 ++++++++++++++++----
>  sysdeps/unix/sysv/linux/unlockpt.c | 21 +++++----------------
>  2 files changed, 21 insertions(+), 20 deletions(-)
> 
> diff --git a/login/tst-grantpt.c b/login/tst-grantpt.c
> index 1d7a220fcf..8ca901ef94 100644
> --- a/login/tst-grantpt.c
> +++ b/login/tst-grantpt.c
> @@ -1,4 +1,4 @@
> -/* Test for grantpt error corner cases.
> +/* Test for grantpt, unlockpt error corner cases.
>     Copyright (C) 2001-2020 Free Software Foundation, Inc.
>     This file is part of the GNU C Library.
>  
> @@ -28,7 +28,7 @@
>  #include <support/temp_file.h>
>  #include <support/xunistd.h>
>  
> -/* Test grantpt with a closed descriptor.  */
> +/* Test grantpt, unlockpt with a closed descriptor.  */
>  static void
>  test_ebadf (void)
>  {
> @@ -48,9 +48,12 @@ test_ebadf (void)
>        printf ("grantpt(): expected: return = %d, errno = %d\n", -1, EBADF);
>        printf ("           got: return = %d, errno = %d\n", ret, err);
>      }
> +
> +  TEST_COMPARE (unlockpt (fd), -1);
> +  TEST_COMPARE (errno, EBADF);
>  }

Ok.

>  
> -/* Test grantpt on a regular file.  */
> +/* Test grantpt, unlockpt on a regular file.  */
>  static void
>  test_einval (void)
>  {
> @@ -68,10 +71,13 @@ test_einval (void)
>        printf ("           got: return = %d, errno = %d\n", ret, err);
>      }
>  
> +  TEST_COMPARE (unlockpt (fd), -1);
> +  TEST_COMPARE (errno, EINVAL);
> +
>    xclose (fd);
>  }
>  

Ok.

> -/* Test grantpt on a non-ptmx pseudo-terminal.  */
> +/* Test grantpt, unlockpt on a non-ptmx pseudo-terminal.  */
>  static void
>  test_not_ptmx (void)
>  {
> @@ -80,6 +86,9 @@ test_not_ptmx (void)
>    TEST_COMPARE (grantpt (ptmx), 0);
>    TEST_COMPARE (unlockpt (ptmx), 0);
>  
> +  /* A second unlock succeeds as well.  */
> +  TEST_COMPARE (unlockpt (ptmx), 0);
> +
>    const char *name = ptsname (ptmx);
>    TEST_VERIFY_EXIT (name != NULL);
>    int pts = open (name, O_RDWR | O_NOCTTY);

Ok.

> @@ -88,6 +97,9 @@ test_not_ptmx (void)
>    TEST_COMPARE (grantpt (pts), -1);
>    TEST_COMPARE (errno, EINVAL);
>  
> +  TEST_COMPARE (unlockpt (pts), -1);
> +  TEST_COMPARE (errno, EINVAL);
> +
>    xclose (pts);
>    xclose (ptmx);
>  }

Ok.

> diff --git a/sysdeps/unix/sysv/linux/unlockpt.c b/sysdeps/unix/sysv/linux/unlockpt.c
> index 3a0ac7a96c..4d98abece0 100644
> --- a/sysdeps/unix/sysv/linux/unlockpt.c
> +++ b/sysdeps/unix/sysv/linux/unlockpt.c
> @@ -27,22 +27,11 @@
>  int
>  unlockpt (int fd)
>  {
> -#ifdef TIOCSPTLCK
> -  int save_errno = errno;
>    int unlock = 0;
>  
> -  if (__ioctl (fd, TIOCSPTLCK, &unlock))
> -    {
> -      if (errno == EINVAL)
> -	{
> -	  __set_errno (save_errno);
> -	  return 0;
> -	}
> -      else
> -	return -1;
> -    }
> -#endif
> -  /* If we have no TIOCSPTLCK ioctl, all slave pseudo terminals are
> -     unlocked by default.  */
> -  return 0;
> +  int ret = __ioctl (fd, TIOCSPTLCK, &unlock);
> +  if (ret != 0 && errno == ENOTTY)
> +    /* POSIX mandates EINVAL for non-ptmx descriptors.  */
> +    __set_errno (EINVAL);
> +  return ret;
>  }
> 

Ok.