Fix futimesat for older MicroBlaze kernels (bug 16648)

Continuing the fixes for __ASSUME_* issues in preparation for moving
to a 2.6.32 minimum kernel version, this *untested* patch fixes bug
16648, the definition of __ASSUME_ATFCTS meaning that the futimesat
syscall is assumed for all MicroBlaze kernels despite not being
present until 2.6.33.

__ASSUME_ATFCTS controls conditionals relating to a lot of different
syscalls in Linux-specific code (fstatat64 faccessat fchmodat fchownat
futimesat newfstatat linkat mkdirat openat readlinkat renameat
symlinkat unlinkat mknodat), where whether newfstatat fstatat64
futimesat are used depends on the architecture, as well as controlling
whether openat64_not_cancel_3 is expected to work in
sysdeps/posix/getcwd.c.  The assumptions are all OK as of 2.6.32
except for this MicroBlaze case, and it's generally desirable to get
rid of as many of the __ASSUME_ATFCTS conditionals as possible, to
simplify the code (the fallbacks include potential unbounded dynamic
stack allocations).  Thus, rather than the simplest approach of
undefining __ASSUME_ATFCTS for older kernels on MicroBlaze, this patch
takes the approach of using the linux-generic implementation of
futimesat for MicroBlaze kernels before 2.6.33 (all such kernels have
the utimensat syscall).

2014-03-19  Joseph Myers  <joseph@codesourcery.com>

	[BZ #16648]
	* sysdeps/unix/sysv/linux/microblaze/kernel-features.h
	[__LINUX_KERNEL_VERSION >= 0x020621] (__ASSUME_FUTIMESAT): Define.
	* sysdeps/unix/sysv/linux/microblaze/futimesat.c: New file.

(CC:ing MicroBlaze maintainer for this patch.)

> Continuing the fixes for __ASSUME_* issues in preparation for moving
> to a 2.6.32 minimum kernel version, this *untested* patch fixes bug
> 16648, the definition of __ASSUME_ATFCTS meaning that the futimesat
> syscall is assumed for all MicroBlaze kernels despite not being
> present until 2.6.33.
> 
> __ASSUME_ATFCTS controls conditionals relating to a lot of different
> syscalls in Linux-specific code (fstatat64 faccessat fchmodat fchownat
> futimesat newfstatat linkat mkdirat openat readlinkat renameat
> symlinkat unlinkat mknodat), where whether newfstatat fstatat64
> futimesat are used depends on the architecture, as well as controlling
> whether openat64_not_cancel_3 is expected to work in
> sysdeps/posix/getcwd.c.  The assumptions are all OK as of 2.6.32
> except for this MicroBlaze case, and it's generally desirable to get
> rid of as many of the __ASSUME_ATFCTS conditionals as possible, to
> simplify the code (the fallbacks include potential unbounded dynamic
> stack allocations).  Thus, rather than the simplest approach of
> undefining __ASSUME_ATFCTS for older kernels on MicroBlaze, this patch
> takes the approach of using the linux-generic implementation of
> futimesat for MicroBlaze kernels before 2.6.33 (all such kernels have
> the utimensat syscall).
> 
> 2014-03-19  Joseph Myers  <joseph@codesourcery.com>
> 
> 	[BZ #16648]
> 	* sysdeps/unix/sysv/linux/microblaze/kernel-features.h
> 	[__LINUX_KERNEL_VERSION >= 0x020621] (__ASSUME_FUTIMESAT): Define.
> 	* sysdeps/unix/sysv/linux/microblaze/futimesat.c: New file.
> 
> diff --git a/sysdeps/unix/sysv/linux/microblaze/futimesat.c b/sysdeps/unix/sysv/linux/microblaze/futimesat.c
> new file mode 100644
> index 0000000..7037c04
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/microblaze/futimesat.c
> @@ -0,0 +1,30 @@
> +/* Implement futimesat for MicroBlaze.
> +   Copyright (C) 2014 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/>.  */
> +
> +/* MicroBlaze always had the utimensat syscall but gained the
> +   futimesat syscall later, so use the linux-generic implementation of
> +   futimesat in terms of the utimensat syscall unless the futimesat
> +   syscall is known to be available.  */
> +
> +#include <kernel-features.h>
> +
> +#ifdef __ASSUME_FUTIMESAT
> +# include <sysdeps/unix/sysv/linux/futimesat.c>
> +#else
> +# include <sysdeps/unix/sysv/linux/generic/futimesat.c>
> +#endif
> diff --git a/sysdeps/unix/sysv/linux/microblaze/kernel-features.h b/sysdeps/unix/sysv/linux/microblaze/kernel-features.h
> index f9a61a9..e7f6db2 100644
> --- a/sysdeps/unix/sysv/linux/microblaze/kernel-features.h
> +++ b/sysdeps/unix/sysv/linux/microblaze/kernel-features.h
> @@ -41,6 +41,11 @@
>  # define __ASSUME_SENDMMSG_SYSCALL       1
>  #endif
>  
> +/* Support for the futimesat syscall was added in 2.6.33.  */
> +#if __LINUX_KERNEL_VERSION >= 0x020621
> +# define __ASSUME_FUTIMESAT              1
> +#endif
> +
>  #include_next <kernel-features.h>
>  
>  /* The MicroBlaze kernel does not support the pselect6, preadv and
> 
> -- 
> Joseph S. Myers
> joseph@codesourcery.com

Ping.  This patch 
<https://sourceware.org/ml/libc-alpha/2014-03/msg00585.html> is pending 
review.  Together with the MicroBlaze parts of 
<https://sourceware.org/ml/libc-alpha/2014-03/msg00835.html> that 
completes the fixes needed in preparation to increase the minimum kernel 
version to 2.6.32.

> -----Original Message-----

> From: Joseph Myers [mailto:joseph@codesourcery.com]

> Sent: Wednesday, 26 March 2014 10:41 am

> To: libc-alpha@sourceware.org

> Cc: David Holsgrove

> Subject: Ping Re: Fix futimesat for older MicroBlaze kernels (bug 16648)

> 

> Ping.  This patch

> <https://sourceware.org/ml/libc-alpha/2014-03/msg00585.html> is pending

> review.  Together with the MicroBlaze parts of

> <https://sourceware.org/ml/libc-alpha/2014-03/msg00835.html> that

> completes the fixes needed in preparation to increase the minimum kernel

> version to 2.6.32.

> 


Apologies for the delay, I've tested and the patch looks good for Microblaze - please apply.

thanks Joseph,

David


> --

> Joseph S. Myers

> joseph@codesourcery.com