Adding support for libseccomp in configure and Makefile (v8)

Adding basic options to the configure script to use libseccomp or not.
The default is set to 'no'. If the flag --enable-libseccomp is used, the
script will check for its existence using pkg-config.

Signed-off-by: Eduardo Otubo <otubo@linux.vnet.ibm.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
---
v1 -> v2:
 - As I removed all the code related to seccomp from vl.c, I created
   qemu-seccomp.[ch].
 - Also making the configure script to add the specific line to
   Makefile.obj in order to compile with appropriate support to seccomp.

v2 -> v3:
 - Removing the line from Makefile.obj and adding it to Makefile.objs.
 - Marking libseccomp default option to 'yes' in the configure script.

v3 -> v8:
 - fix configure probe if libseccomp isn't available (aliguori)

Makefile.objs

@@ -96,6 +96,12 @@ common-obj-y += qemu-timer.o qemu-timer-common.o
 
 common-obj-$(CONFIG_SLIRP) += slirp/
 
+######################################################################
+# libseccomp
+ifeq ($(CONFIG_SECCOMP),y)
+common-obj-y += qemu-seccomp.o
+endif
+
 ######################################################################
 # libuser
 

configure

@@ -218,6 +218,7 @@ zlib="yes"
 guest_agent="yes"
 libiscsi=""
 coroutine=""
+seccomp=""
 
 # parse CC options first
 for opt do
@@ -864,6 +865,10 @@ for opt do
   ;;
   --disable-guest-agent) guest_agent="no"
   ;;
+  --enable-seccomp) seccomp="yes"
+  ;;
+  --disable-seccomp) seccomp="no"
+  ;;
   *) echo "ERROR: unknown option $opt"; show_help="yes"
   ;;
   esac
@@ -1152,6 +1157,8 @@ echo "  --disable-usb-redir      disable usb network redirection support"
 echo "  --enable-usb-redir       enable usb network redirection support"
 echo "  --disable-guest-agent    disable building of the QEMU Guest Agent"
 echo "  --enable-guest-agent     enable building of the QEMU Guest Agent"
+echo "  --disable-seccomp        disable seccomp support"
+echo "  --enable-seccomp         enables seccomp support"
 echo "  --with-coroutine=BACKEND coroutine backend. Supported options:"
 echo "                           gthread, ucontext, sigaltstack, windows"
 echo ""
@@ -1413,6 +1420,20 @@ EOF
     fi
 fi
 
+##########################################
+# libseccomp check
+
+if test "$seccomp" != "no" ; then
+    if $pkg_config libseccomp --modversion >/dev/null 2>&1; then
+        LIBS=`$pkg_config --libs libseccomp`
+	seccomp="yes"
+    else
+	seccomp="no"
+	if test "$seccomp" = "yes"; then
+            feature_not_found "libseccomp"
+	fi
+    fi
+fi
 ##########################################
 # xen probe
 
@@ -3143,6 +3164,7 @@ echo "usb net redir     $usb_redir"
 echo "OpenGL support    $opengl"
 echo "libiscsi support  $libiscsi"
 echo "build guest agent $guest_agent"
+echo "seccomp support   $seccomp"
 echo "coroutine backend $coroutine_backend"
 
 if test "$sdl_too_old" = "yes"; then
@@ -3438,6 +3460,10 @@ if test "$libiscsi" = "yes" ; then
   echo "CONFIG_LIBISCSI=y" >> $config_host_mak
 fi
 
+if test "$seccomp" = "yes"; then
+  echo "CONFIG_SECCOMP=y" >> $config_host_mak
+fi
+
 # XXX: suppress that
 if [ "$bsd" = "yes" ] ; then
   echo "CONFIG_BSD=y" >> $config_host_mak