introduce timer_new_opaque callback

Add a new callback that supports CFI better by avoiding having function pointers
in the external libslirp API.  Instead, the new API passes an opaque integer
and requests the application to call a new libslirp function when the timer
expires.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 15 insertions, 1 deletions

diff --git a/src/libslirp.h b/src/libslirp.h
index 546f2f9..8eb47a0 100644
--- a/src/libslirp.h
+++ b/src/libslirp.h
@@ -63,7 +63,8 @@ typedef struct SlirpCb {
     void (*guest_error)(const char *msg, void *opaque);
     /* Return the virtual clock value in nanoseconds */
     int64_t (*clock_get_ns)(void *opaque);
-    /* Create a new timer with the given callback and opaque data */
+    /* Create a new timer with the given callback and opaque data. Not
+     * needed if timer_new_opaque is provided. */
     void *(*timer_new)(SlirpTimerCb cb, void *cb_opaque, void *opaque);
     /* Remove and free a timer */
     void (*timer_free)(void *timer, void *opaque);
@@ -76,6 +77,14 @@ typedef struct SlirpCb {
     /* Kick the io-thread, to signal that new events may be processed because some TCP buffer
      * can now receive more data, i.e. slirp_socket_can_recv will return 1. */
     void (*notify)(void *opaque);
+
+    /*
+     * Fields introduced in SlirpConfig version 4 begin
+     */
+
+    /* Create a new timer.  When the timer fires, the application passes
+     * the SlirpTimerId and cb_opaque to slirp_handle_timer.  */
+    void *(*timer_new_opaque)(SlirpTimerId id, void *cb_opaque, void *opaque);
 } SlirpCb;
 
 #define SLIRP_CONFIG_VERSION_MIN 1
@@ -171,6 +180,11 @@ void slirp_pollfds_poll(Slirp *slirp, int select_error,
  * guest network, to be interpreted by slirp. */
 void slirp_input(Slirp *slirp, const uint8_t *pkt, int pkt_len);
 
+/* This is called by the application when a timer expires, if it provides
+ * the timer_new_opaque callback.  It is not needed if the application only
+ * uses timer_new. */
+void slirp_handle_timer(Slirp *slirp, SlirpTimerId id, void *cb_opaque);
+
 /* These set up / remove port forwarding between a host port in the real world
  * and the guest network. */
 int slirp_add_hostfwd(Slirp *slirp, int is_udp, struct in_addr host_addr,