Use sigwait instead of sigwaitinfo.

Fix compilation failure on Darwin.
Signed-off-by: NTristan Gingold <gingold@adacore.com>
Signed-off-by: NBlue Swirl <blauwirbel@gmail.com>

compatfd.c

@@ -26,45 +26,45 @@ struct sigfd_compat_info
 static void *sigwait_compat(void *opaque)
 {
     struct sigfd_compat_info *info = opaque;
-    int err;
     sigset_t all;
 
     sigfillset(&all);
     sigprocmask(SIG_BLOCK, &all, NULL);
 
-    do {
-        siginfo_t siginfo;
+    while (1) {
+        int sig;
+        int err;
 
-        err = sigwaitinfo(&info->mask, &siginfo);
-        if (err == -1 && errno == EINTR) {
-            err = 0;
-            continue;
-        }
-
-        if (err > 0) {
-            char buffer[128];
+        err = sigwait(&info->mask, &sig);
+        if (err != 0) {
+            if (errno == EINTR) {
+                continue;
+            } else {
+                return NULL;
+            }
+        } else {
+            struct qemu_signalfd_siginfo buffer;
             size_t offset = 0;
 
-            memcpy(buffer, &err, sizeof(err));
+            memset(&buffer, 0, sizeof(buffer));
+            buffer.ssi_signo = sig;
+
             while (offset < sizeof(buffer)) {
                 ssize_t len;
 
-                len = write(info->fd, buffer + offset,
+                len = write(info->fd, (char *)&buffer + offset,
                             sizeof(buffer) - offset);
                 if (len == -1 && errno == EINTR)
                     continue;
 
                 if (len <= 0) {
-                    err = -1;
-                    break;
+                    return NULL;
                 }
 
                 offset += len;
             }
         }
-    } while (err >= 0);
-
-    return NULL;
+    }
 }
 
 static int qemu_signalfd_compat(const sigset_t *mask)