optionally build with vsock support

If we cannot find /usr/include/linux/vm_sockets.h locally, do not build
with vsock support.

Signed-off-by: Peng Tao <bergwolf@gmail.com>

Author: bergwolf

configure.ac

@@ -74,7 +74,11 @@ AC_SUBST(SYSTEMD_SYSTEMUNIT)
 AM_CONDITIONAL(SYSTEMD, test "x${SYSTEMD_SYSTEMUNIT}" != "xno" )
 
 AC_CHECK_FILE([/usr/include/linux/vm_sockets.h],
-	      [], [AC_MSG_ERROR(Cannot find linux/vm_sockets.h)])
+	      [have_vsock=yes], [have_vsock=no])
+if test "x$have_vsock" == "xyes"; then
+    AC_DEFINE_UNQUOTED([HAVE_VSOCK], 1, [enable vm socket support])
+fi
+AM_CONDITIONAL([HAVE_VSOCK], [test "x$have_vsock" == "xyes"])
 
 AC_CONFIG_FILES([
   Makefile
@@ -91,6 +95,8 @@ AC_MSG_RESULT([
 	with-vbox:	${with_vbox}
 	with-aarch64:	${with_aarch64}
 
+	vsock-support:  ${have_vsock}
+
 	compiler:          ${CC}
 	cflags:            ${CFLAGS}
 	suid cflags:       ${SUID_CFLAGS}

src/Makefile.am

@@ -1,3 +1,6 @@
 AM_CFLAGS = -Wall -Werror
 bin_PROGRAMS=hyperstart
-hyperstart_SOURCES=init.c jsmn.c net.c util.c parse.c parson.c container.c exec.c event.c portmapping.c vsock.c
+hyperstart_SOURCES=init.c jsmn.c net.c util.c parse.c parson.c container.c exec.c event.c portmapping.c
+if HAVE_VSOCK
+hyperstart_SOURCES+=vsock.c
+endif

src/vsock.h

@@ -2,10 +2,28 @@
 #define _VSOCK_H_
 
 #include "event.h"
+#include "../config.h"
 
+#ifdef HAVE_VSOCK
 int probe_vsock_device(void);
 int hyper_create_vsock_listener(unsigned short port);
 int hyper_vsock_accept(struct hyper_event *he, int efd,
 		       struct hyper_event *ne, struct hyper_event_ops *ops);
+#else /*HAVE_VSOCK*/
+static int probe_vsock_device(void)
+{
+	return -1;
+}
+static int hyper_create_vsock_listener(unsigned short port)
+{
+	return -1;
+}
+static int hyper_vsock_accept(struct hyper_event *he, int efd,
+		       struct hyper_event *ne, struct hyper_event_ops *ops)
+{
+	return -1;
+}
+
+#endif /*HAVE_VSOCK*/
 
 #endif