X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~mdw/git/secnet/blobdiff_plain/cf5f1149caccf65c700e73fc0e9212c916df3610..ee697dd98d0f9aca6b9df7ffb32d3a15b4e33d6d:/secnet.h

diff --git a/secnet.h b/secnet.h
index 629851b..0e2e1f7 100644
--- a/secnet.h
+++ b/secnet.h
@@ -13,6 +13,7 @@
 #include <assert.h>
 #include <fcntl.h>
 #include <unistd.h>
+#include <errno.h>
 #include <sys/poll.h>
 #include <sys/types.h>
 #include <sys/time.h>
@@ -200,6 +201,16 @@ typedef int beforepoll_fn(void *st, struct pollfd *fds, int *nfds_io,
 			  int *timeout_io);
 typedef void afterpoll_fn(void *st, struct pollfd *fds, int nfds);
 
+/* void BEFOREPOLL_WANT_FDS(int want);
+ *   Expects: int *nfds_io;
+ *   Can perform non-local exit.
+ * Checks whether there is space for want fds.  If so, sets *nfds_io.
+ * If not, sets *nfds_io and returns. */
+#define BEFOREPOLL_WANT_FDS(want) do{				\
+    if (*nfds_io<(want)) { *nfds_io=(want); return ERANGE; }	\
+    *nfds_io=(want);						\
+  }while(0)
+
 /* Register interest in the main loop of the program. Before a call
    to poll() your supplied beforepoll function will be called. After
    the call to poll() the supplied afterpoll function will be called.