posix: Use posix_spawn on system

This patch uses posix_spawn on system implementation.  On Linux this has
the advantage of much lower memory consumption (usually 32 Kb minimum for
the mmap stack area).

Although POSIX does not require, glibc system implementation aims to be
thread and cancellation safe.  The cancellation code is moved to generic
implementation and enabled iff SIGCANCEL is defined (similar on how the
cancellation handler is enabled on nptl-init.c).

Checked on x86_64-linux-gnu, i686-linux-gnu, aarch64-linux-gnu,
arm-linux-gnueabihf, and powerpc64le-linux-gnu.

	* sysdeps/unix/sysv/linux/spawni.c (__spawni_child): Use
	__sigismember instead of sigismember.
	* sysdeps/posix/system.c [SIGCANCEL] (cancel_handler_args,
	cancel_handler): New definitions.
	(CLEANUP_HANDLER, CLEANUP_RESET): Likewise.
	(DO_LOCK, DO_UNLOCK, INIT_LOCK, ADD_REF, SUB_REF): Remove.
	(do_system): Use posix_spawn instead of fork and execl and remove
	reentracy code.
	* sysdeps/generic/not-errno.h (__kill_noerrno): New prototype.
	* sysdeps/unix/sysv/linux/not-errno.h (__kill_noerrno): Likewise.
	* sysdeps/unix/sysv/linux/ia64/system.c: Remove file.
	* sysdeps/unix/sysv/linux/s390/system.c: Likewise.
	* sysdeps/unix/sysv/linux/sparc/system.c: Likewise.
	* sysdeps/unix/sysv/linux/system.c: Likewise.

1 files changed, 0 insertions, 29 deletions

diff --git a/sysdeps/unix/sysv/linux/s390/system.c b/sysdeps/unix/sysv/linux/s390/system.c
deleted file mode 100644
index d8ef461334..0000000000
--- a/sysdeps/unix/sysv/linux/s390/system.c
+++ /dev/null
@@ -1,29 +0,0 @@
-/* Copyright (C) 2003-2018 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/>.  */
-
-/* We have to and actually can handle cancelable system().  The big
-   problem: we have to kill the child process if necessary.  To do
-   this a cleanup handler has to be registered and is has to be able
-   to find the PID of the child.  The main problem is to reliable have
-   the PID when needed.  It is not necessary for the parent thread to
-   return.  It might still be in the kernel when the cancellation
-   request comes.  Therefore we have to use the clone() calls ability
-   to have the kernel write the PID into the user-level variable.  */
-#define FORK() \
-  INLINE_SYSCALL (clone, 3, 0, CLONE_PARENT_SETTID | SIGCHLD, &pid)
-
-#include "../system.c"