use syscall numbers from Linux kernel headers

__NR_setns is defined in the Linux kernel headers in linux/unistd.h.
The full Linux kernel sources are not necessary for compilation.

Signed-off-by: David Ward <david.ward@ll.mit.edu>
Signed-off-by: Daniel Lezcano <dlezcano@fr.ibm.com>

config/linux.m4

@@ -1,76 +0,0 @@
-AC_DEFUN([AC_LINUX],
-[
-	AC_LINUX_DIR()
-	AC_LINUX_SRCARCH()
-])
-
-AC_DEFUN([AS_TRY_LINUX_DIR],
-	[AC_MSG_CHECKING(for Linux in $1)
-
-	if test -f "$1/Makefile" ; then
-		result=yes
-		$2
-	else
-		result="not found"
-		$3
-	fi
-
-	AC_MSG_RESULT($result)
-])
-
-AC_DEFUN([AC_LINUX_DIR],
-[
-	AC_ARG_WITH([linuxdir],
-		[AC_HELP_STRING([--with-linuxdir=DIR],
-			[specify path to Linux source directory])],
-		[LINUX_DIR="${withval}"],
-		[LINUX_DIR=default])
-
-	dnl if specified, use the specified one
-	if test "${LINUX_DIR}" != "default" ; then
-		AS_TRY_LINUX_DIR([${LINUX_DIR}], , AC_MSG_ERROR([Linux dir not found]) )
-	fi
-
-	dnl if not specified, first try with previously set LINUX_KERNEL_RELEASE
-	if test "${LINUX_DIR}" = "default" ; then
-		dir="/lib/modules/$LINUX_KERNEL_RELEASE/build";
-		AS_TRY_LINUX_DIR([${dir}], [LINUX_DIR=${dir}], )
-	fi
-
-	dnl next try using the kernel source dir
-	if test "${LINUX_DIR}" = "default" ; then
-		dir="/usr/src/linux-$LINUX_KERNEL_RELEASE";
-		AS_TRY_LINUX_DIR([${dir}], [LINUX_DIR=${dir}], )
-	fi
-
-	dnl then try a common default of /usr/src/linux
-	if test "${LINUX_DIR}" = "default" ; then
-		dir="/usr/src/linux";
-		AS_TRY_LINUX_DIR([${dir}], [LINUX_DIR=${dir}], )
-	fi
-
-	dnl if still nothing found, fail
-	if test "${LINUX_DIR}" = "default" ; then
-		AC_MSG_WARN([Linux source directory not found])
-	fi
-
-	AC_SUBST(LINUX_DIR)
-])
-
-AC_DEFUN([AC_LINUX_SRCARCH],[
-	AC_MSG_CHECKING(for linux SRCARCH)
-
-	case "${host}" in
-	i[[3456]]86-*) LINUX_SRCARCH=x86;;
-	x86_64-*) LINUX_SRCARCH=x86;;
-	powerpc*-*) LINUX_SRCARCH=powerpc;;
-	s390*-*) LINUX_SRCARCH=s390;;
-	arm*-*) LINUX_SRCARCH=arm;;
-	mips*-*) LINUX_SRCARCH=mips;;
-	sparc*-*) LINUX_SRCARCH=sparc;;
-	*) AC_MSG_ERROR([architecture ${host} not supported]);;
-	esac
-
-	AC_MSG_RESULT(${LINUX_SRCARCH})
-	AC_SUBST(LINUX_SRCARCH)
-])

configure.ac

@@ -65,13 +65,13 @@ AC_SUBST(LXCROOTFSMOUNT, "${with_rootfs_path}")
 AC_SUBST(LXCINITDIR, ['${libexecdir}/lxc'])
 AC_SUBST(LXCTEMPLATEDIR, ['${libdir}/lxc/templates'])
 
-AC_CHECK_HEADERS([linux/netlink.h linux/genetlink.h],
+AC_CHECK_HEADERS([linux/unistd.h linux/netlink.h linux/genetlink.h],
 				  [],
-				  AC_MSG_ERROR([netlink headers not found. Please install the linux kernel headers.]),
+				  AC_MSG_ERROR([Please install the Linux kernel headers.]),
 				  [#include <sys/socket.h>
 		 ])
 
-AC_CHECK_HEADERS([sys/capability.h], [], AC_MSG_ERROR([please install libcap-devel.]),
+AC_CHECK_HEADERS([sys/capability.h], [], AC_MSG_ERROR([Please install the libcap development files.]),
 [#include <sys/types.h>
 #include <sys/capability.h>])
 AC_CHECK_LIB(cap,cap_set_proc,caplib=yes,caplib=no)
@@ -91,8 +91,6 @@ AC_CHECK_HEADERS([sys/signalfd.h])
 
 AC_PROG_GCC_TRADITIONAL
 
-AC_LINUX
-
 if test "x$GCC" = "xyes"; then
   CFLAGS="$CFLAGS -Wall"
 fi

src/lxc/Makefile.am

@@ -131,14 +131,3 @@ install-exec-local: install-soPROGRAMS
 
 uninstall-local:
 	$(RM) $(DESTDIR)$(libdir)/liblxc.so*
-
-namespace.c: setns.h
-
-setns.h:
-	-$(CC) $(CPPFLAGS) -M -MT$@ $(LINUX_DIR)/arch/$(LINUX_SRCARCH)/include/asm/unistd.h >setns.P
-	-$(CPP) $(CPPFLAGS) -dM $(LINUX_DIR)/arch/$(LINUX_SRCARCH)/include/asm/unistd.h |grep setns > $@
-
-clean-local:
-	$(RM) setns.h setns.P
-
--include setns.P

src/lxc/attach.c

@@ -30,6 +30,7 @@
 #include <fcntl.h>
 #include <sys/param.h>
 #include <sys/prctl.h>
+#include <linux/unistd.h>
 
 #if !HAVE_DECL_PR_CAPBSET_DROP
 #define PR_CAPBSET_DROP 24
@@ -42,8 +43,6 @@
 #include "cgroup.h"
 #include "config.h"
 
-#include "setns.h"
-
 lxc_log_define(lxc_attach, lxc);
 
 int setns(int fd, int nstype)