wait_socket: make c89 compliant and use two fd_sets for select()

src/session.c

@@ -528,6 +528,7 @@ int _libssh2_wait_socket(LIBSSH2_SESSION *session)
         /* figure out what to wait for */
         dir = libssh2_session_block_directions(session);
 
+        {
 #ifdef HAVE_POLL
             struct pollfd sockets[1];
 
@@ -543,7 +544,8 @@ int _libssh2_wait_socket(LIBSSH2_SESSION *session)
 
             rc = poll(sockets, 1, seconds_to_next ? seconds_to_next / 1000 : -1);
 #else
-        fd_set fd;
+            fd_set rfd;
+            fd_set wfd;
             fd_set *writefd = NULL;
             fd_set *readfd = NULL;
             struct timeval tv;
@@ -551,21 +553,25 @@ int _libssh2_wait_socket(LIBSSH2_SESSION *session)
             tv.tv_sec = seconds_to_next;
             tv.tv_usec = 0;
 
-        FD_ZERO(&fd);
+            if(dir & LIBSSH2_SESSION_BLOCK_INBOUND) {
-        FD_SET(session->socket_fd, &fd);
+                FD_ZERO(&rfd);
+                FD_SET(session->socket_fd, &rfd);
+                readfd = &rfd;
+            }
 
-        if(dir & LIBSSH2_SESSION_BLOCK_INBOUND)
+            if(dir & LIBSSH2_SESSION_BLOCK_OUTBOUND) {
-            readfd = &fd;
+                FD_ZERO(&wfd);
+                FD_SET(session->socket_fd, &wfd);
+                writefd = &wfd;
+            }
 
-        if(dir & LIBSSH2_SESSION_BLOCK_OUTBOUND)
+            /* Note that this COULD be made to use a timeout that perhaps
-            writefd = &fd;
+               could be customizable by the app or something... */
-
-        /* Note that this COULD be made to use a timeout that perhaps could be
-           customizable by the app or something... */
             rc = select(session->socket_fd + 1, readfd, writefd, NULL,
                         seconds_to_next ? &tv : NULL);
 #endif
         }
+    }
 
     if(rc <= 0) {
         /* timeout (or error), bail out with a timeout error */