vmstate: only enable when building under GNU C

To be able to use typeof.

Fixes #60

4 files changed, 29 insertions, 3 deletions

diff --git a/src/libslirp.h b/src/libslirp.h
index 4f156b6..63a9600 100644
--- a/src/libslirp.h
+++ b/src/libslirp.h
@@ -279,7 +279,7 @@ char *slirp_neighbor_info(Slirp *slirp);
 /* Save the slirp state through the write_cb. The opaque pointer is passed as
  * such to the write_cb. */
 SLIRP_EXPORT
-void slirp_state_save(Slirp *s, SlirpWriteCb write_cb, void *opaque);
+int slirp_state_save(Slirp *s, SlirpWriteCb write_cb, void *opaque);
 
 /* Returns the version of the slirp state, to be saved along the state */
 SLIRP_EXPORT
diff --git a/src/state.c b/src/state.c
index 8708547..d5689ba 100644
--- a/src/state.c
+++ b/src/state.c
@@ -26,6 +26,8 @@
 #include "vmstate.h"
 #include "stream.h"
 
+#ifdef HAVE_VMSTATE
+
 static int slirp_tcp_post_load(void *opaque, int version)
 {
     tcp_template((struct tcpcb *)opaque);
@@ -307,7 +309,7 @@ static const VMStateDescription vmstate_slirp = {
                                 VMSTATE_END_OF_LIST() }
 };
 
-void slirp_state_save(Slirp *slirp, SlirpWriteCb write_cb, void *opaque)
+int slirp_state_save(Slirp *slirp, SlirpWriteCb write_cb, void *opaque)
 {
     struct gfwd_list *ex_ptr;
     SlirpOStream f = {
@@ -330,6 +332,8 @@ void slirp_state_save(Slirp *slirp, SlirpWriteCb write_cb, void *opaque)
     slirp_ostream_write_u8(&f, 0);
 
     slirp_vmstate_save_state(&f, &vmstate_slirp, slirp);
+
+    return 0;
 }
 
 
@@ -373,6 +377,19 @@ int slirp_state_load(Slirp *slirp, int version_id, SlirpReadCb read_cb,
     return slirp_vmstate_load_state(&f, &vmstate_slirp, slirp, version_id);
 }
 
+#else /* HAVE_VMSTATE */
+int slirp_state_save(Slirp *slirp, SlirpWriteCb write_cb, void *opaque)
+{
+    return -ENOSYS;
+}
+
+int slirp_state_load(Slirp *slirp, int version_id, SlirpReadCb read_cb,
+                     void *opaque)
+{
+    return -ENOSYS;
+}
+#endif /* HAVE_VMSTATE */
+
 int slirp_state_version(void)
 {
     return 4;
diff --git a/src/vmstate.c b/src/vmstate.c
index 68cc172..c7fc5a3 100644
--- a/src/vmstate.c
+++ b/src/vmstate.c
@@ -45,6 +45,8 @@
 #include "stream.h"
 #include "vmstate.h"
 
+#ifdef HAVE_VMSTATE
+
 static int get_nullptr(SlirpIStream *f, void *pv, size_t size,
                        const VMStateField *field)
 {
@@ -442,3 +444,5 @@ int slirp_vmstate_load_state(SlirpIStream *f, const VMStateDescription *vmsd,
     }
     return ret;
 }
+
+#endif /* HAVE_VMSTATE */
diff --git a/src/vmstate.h b/src/vmstate.h
index e3e2459..64dd256 100644
--- a/src/vmstate.h
+++ b/src/vmstate.h
@@ -39,6 +39,9 @@
 #ifndef VMSTATE_H_
 #define VMSTATE_H_
 
+#ifdef __GNUC__
+#define HAVE_VMSTATE 1
+
 #include <unistd.h>
 #include <stdint.h>
 #include <stdbool.h>
@@ -392,4 +395,6 @@ extern const VMStateInfo slirp_vmstate_info_tmp;
         .flags = VMS_END,     \
     }
 
-#endif
+#endif /* __GNUC__ */
+
+#endif /* VMSTATE_H_ */