glibc/sysdeps/unix/sysv/linux/recvmmsg.c
Joseph Myers 9a45f54310 Simplify recvmmsg code.
Now we can assume a kernel with recvmmsg support, this patch
simplifies the implementation to be similar to that for accept4:
either using socketcall or the syscall according to whether the
syscall is known to be available, without further fallback
implementations.

(In fact further simplification is possible, getting rid of the
__ASSUME_*_SYSCALL_WITH_SOCKETCALL macros now that the minimum kernel
is guaranteed support for all of accept4, recvmmsg, sendmmsg, whether
through syscalls or through socketcall.  I intend to do that for all
of accept4 / recvmmsg / sendmmsg together - so making their
implementations just like those for older socket functions - once the
basic cleanup for 3.2 minimum kernel is done for sendmmsg as well as
recvmmsg.)

Tested for x86_64 and x86.

	* sysdeps/unix/sysv/linux/kernel-features.h
	(__ASSUME_RECVMMSG_SYSCALL): Define unconditionally.
	(__ASSUME_RECVMMSG_SOCKETCALL): Remove macro.
	(__ASSUME_RECVMMSG): Likewise.
	* sysdeps/unix/sysv/linux/recvmmsg.c (recvmmsg): Define using
	recvmmsg syscall if it can be assumed to be present, socketcall
	otherwise, with no fallback for runtime failure.
2017-05-09 20:01:01 +00:00

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1.5 KiB
C

/* Copyright (C) 2010-2017 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Andreas Schwab <schwab@redhat.com>, 2010.
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 <sys/socket.h>
#include <sysdep-cancel.h>
#include <sys/syscall.h>
#include <socketcall.h>
#include <kernel-features.h>
int
recvmmsg (int fd, struct mmsghdr *vmessages, unsigned int vlen, int flags,
struct timespec *tmo)
{
/* Do not use the recvmmsg syscall on socketcall architectures unless
it was added at the same time as the socketcall support or can be
assumed to be present. */
#if defined __ASSUME_SOCKETCALL \
&& !defined __ASSUME_RECVMMSG_SYSCALL_WITH_SOCKETCALL \
&& !defined __ASSUME_RECVMMSG_SYSCALL
return SOCKETCALL_CANCEL (recvmmsg, fd, vmessages, vlen, flags, tmo);
#else
return SYSCALL_CANCEL (recvmmsg, fd, vmessages, vlen, flags, tmo);
#endif
}