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.

6 files changed, 16 insertions, 166 deletions

diff --git a/sysdeps/unix/sysv/linux/ia64/system.c b/sysdeps/unix/sysv/linux/ia64/system.c
deleted file mode 100644
index d09fefefe6..0000000000
--- a/sysdeps/unix/sysv/linux/ia64/system.c
+++ /dev/null
@@ -1,30 +0,0 @@
-/* Copyright (C) 2002-2018 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 (clone2, 6, CLONE_PARENT_SETTID | SIGCHLD, NULL, 0, \
-		  &pid, NULL, NULL)
-
-#include <sysdeps/unix/sysv/linux/system.c>
diff --git a/sysdeps/unix/sysv/linux/not-errno.h b/sysdeps/unix/sysv/linux/not-errno.h
index 106ba5c72e..b2f72cfb3d 100644
--- a/sysdeps/unix/sysv/linux/not-errno.h
+++ b/sysdeps/unix/sysv/linux/not-errno.h
@@ -16,6 +16,9 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
+#include <sysdep.h>
+#include <fcntl.h>
+
 /* This function is used on maybe_enable_malloc_check (elf/dl-tunables.c)
    and to avoid having to build/use multiple versions if stack protection
    in enabled it is defined as inline.  */
@@ -33,3 +36,14 @@ __access_noerrno (const char *pathname, int mode)
     return INTERNAL_SYSCALL_ERRNO (res, err);
   return 0;
 }
+
+static inline int
+__kill_noerrno (pid_t pid, int sig)
+{
+  int res;
+  INTERNAL_SYSCALL_DECL (err);
+  res = INTERNAL_SYSCALL_CALL (kill, err, pid, sig);
+  if (INTERNAL_SYSCALL_ERROR_P (res, err))
+    return INTERNAL_SYSCALL_ERRNO (res, err);
+  return 0;
+}
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"
diff --git a/sysdeps/unix/sysv/linux/sparc/system.c b/sysdeps/unix/sysv/linux/sparc/system.c
deleted file mode 100644
index 1f65c83399..0000000000
--- a/sysdeps/unix/sysv/linux/sparc/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_CLONE_SYSCALL (CLONE_PARENT_SETTID | SIGCHLD, 0, &pid, NULL, NULL)
-
-#include "../system.c"
diff --git a/sysdeps/unix/sysv/linux/spawni.c b/sysdeps/unix/sysv/linux/spawni.c
index 9f3a137b5c..dbb6cdd5f0 100644
--- a/sysdeps/unix/sysv/linux/spawni.c
+++ b/sysdeps/unix/sysv/linux/spawni.c
@@ -138,11 +138,11 @@ __spawni_child (void *arguments)
   for (int sig = 1; sig < _NSIG; ++sig)
     {
       if ((attr->__flags & POSIX_SPAWN_SETSIGDEF)
-	  && sigismember (&attr->__sd, sig))
+	  && __sigismember (&attr->__sd, sig))
 	{
 	  sa.sa_handler = SIG_DFL;
 	}
-      else if (sigismember (&hset, sig))
+      else if (__sigismember (&hset, sig))
 	{
 	  if (__is_internal_signal (sig))
 	    sa.sa_handler = SIG_IGN;
diff --git a/sysdeps/unix/sysv/linux/system.c b/sysdeps/unix/sysv/linux/system.c
deleted file mode 100644
index 7cc68a1528..0000000000
--- a/sysdeps/unix/sysv/linux/system.c
+++ /dev/null
@@ -1,76 +0,0 @@
-/* Copyright (C) 2002-2018 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/>.  */
-
-#include <sched.h>
-#include <signal.h>
-#include <string.h>	/* For the real memset prototype.  */
-#include <sysdep.h>
-#include <unistd.h>
-#include <sys/wait.h>
-#include <libc-lock.h>
-
-/* 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.  */
-#ifndef FORK
-# define FORK() \
-  INLINE_SYSCALL (clone, 3, CLONE_PARENT_SETTID | SIGCHLD, 0, &pid)
-#endif
-
-#ifdef _LIBC_REENTRANT
-static void cancel_handler (void *arg);
-
-# define CLEANUP_HANDLER \
-  __libc_cleanup_region_start (1, cancel_handler, &pid)
-
-# define CLEANUP_RESET \
-  __libc_cleanup_region_end (0)
-#endif
-
-
-/* Linux has waitpid(), so override the generic unix version.  */
-#include <sysdeps/posix/system.c>
-
-
-#ifdef _LIBC_REENTRANT
-/* The cancellation handler.  */
-static void
-cancel_handler (void *arg)
-{
-  pid_t child = *(pid_t *) arg;
-
-  INTERNAL_SYSCALL_DECL (err);
-  INTERNAL_SYSCALL (kill, err, 2, child, SIGKILL);
-
-  TEMP_FAILURE_RETRY (__waitpid (child, NULL, 0));
-
-  DO_LOCK ();
-
-  if (SUB_REF () == 0)
-    {
-      (void) __sigaction (SIGQUIT, &quit, (struct sigaction *) NULL);
-      (void) __sigaction (SIGINT, &intr, (struct sigaction *) NULL);
-    }
-
-  DO_UNLOCK ();
-}
-#endif