Re: [RFC][BZ #14627] Make linux close errno to EINPROGRESS when interrupted in signal.

[Adhemerval Zanella <azanella at linux dot vnet dot ibm dot com>]

I wonder if it would break applications that relies on the Linux behavior.

On 05-12-2013 15:10, OndÅej BÃlka wrote:
> Hi,
>
> As was recently said
> https://www.sourceware.org/ml/libc-alpha/2013-12/msg00086.html
>
> linux when close is interrupted by signal closes file descriptor but
> returns EINTR errno which lies application about restartability. As
> kernel does not restart close on SA_RESTART only thing needed is to
> return EINPROGRESS instead EINTR as specified by POSIX.
>
> I do not have actual implementation ready as close is automatically
> generated syscall wrapper.
>
> Second concern is cancelability, there is a close_nocancel macro and
> also in libc.so close is implemented as header before close_nocancel but
> i couldn't find definition.
>
> Could somebody clarify?
>
> As actual implementation one could use something like this. As in fclose
> we use noncancelable version should we also disable cancelability in
> close?
>
> diff --git a/sysdeps/unix/sysv/linux/close.c b/sysdeps/unix/sysv/linux/close.c
> new file mode 100644
> index 0000000..223d6ed
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/close.c
> @@ -0,0 +1,44 @@
> +/* Copyright (C) 2013 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/>.  */
> +
> +#include <errno.h>
> +#include <fcntl.h>
> +#include <stdio.h>
> +#include <sysdep-cancel.h>
> +
> +int
> +__libc_close (int fd)
> +{
> +  if (SINGLE_THREAD_P)
> +    return INLINE_SYSCALL (close, 1, fd);
> +
> +  int oldtype = LIBC_CANCEL_ASYNC ();
> +
> +  int result = INLINE_SYSCALL (close, 1, fd);
> +
> +  if (errno == EINTR)
> +    errno = EINPROGRESS;
> +
> +  LIBC_CANCEL_RESET (oldtype);
> +
> +  return result;
> +}
> +
> +weak_alias (__libc_close, __close)
> +libc_hidden_weak (__close)
> +weak_alias (__libc_close, close)
>