libssh2_poll() no longer relies on C99 features but instead uses alloca()

on systems that have it - and uses a fixed-size array on those that don't.
session.c was also cleaned from a large amount of trailing whitespace.

configure.in

@@ -248,6 +248,8 @@ AC_CHECK_HEADERS([sys/select.h sys/socket.h sys/ioctl.h sys/time.h])
 AC_CHECK_HEADERS([arpa/inet.h netinet/in.h])
 AC_CHECK_FUNCS(poll gettimeofday select)
 
+AC_FUNC_ALLOCA
+
 # Checks for typedefs, structures, and compiler characteristics.
 AC_C_CONST
 AC_C_INLINE

src/session.c

@@ -46,6 +46,9 @@
 #ifdef HAVE_GETTIMEOFDAY
 #include <sys/time.h>
 #endif
+#ifdef HAVE_ALLOCA_H
+#include <alloca.h>
+#endif
 
 /* {{{ libssh2_default_alloc
  */
@@ -432,8 +435,12 @@ LIBSSH2_API LIBSSH2_SESSION *libssh2_session_init_ex(
 /* {{{ libssh2_session_callback_set
  * Set (or reset) a callback function
  * Returns the prior address
+ *
+ * FIXME: this function relies on that we can typecast function pointers
+ * to void pointers, which isn't allowed in ISO C!
  */
-LIBSSH2_API void* libssh2_session_callback_set(LIBSSH2_SESSION *session, int cbtype, void *callback)
+LIBSSH2_API void* libssh2_session_callback_set(LIBSSH2_SESSION *session,
+                                               int cbtype, void *callback)
 {
     void *oldcb;
 
@@ -1142,12 +1149,16 @@ LIBSSH2_API int libssh2_poll(LIBSSH2_POLLFD *fds, unsigned int nfds, long timeou
     unsigned int i, active_fds;
 #ifdef HAVE_POLL
     LIBSSH2_SESSION *session = NULL;
-    struct pollfd sockets[nfds];
+#ifdef HAVE_ALLOCA
-    /* FIXME: (dast) this is not C89 code! However, the prototype for this
+    struct pollfd *sockets = alloca(sizeof(struct pollfd) * nfds);
-       function doesn't provide a session struct so we can't easily use
+#else
-       the user-provided malloc replacement here... I suggest we modify
+    struct pollfd sockets[256];
-       the proto to make it possible. */
 
+    if(nfds > 256)
+      /* systems without alloca use a fixed-size array, this can be fixed
+         if we really want to, at least if the compiler is a C99 capable one */
+      return -1;
+#endif
     /* Setup sockets for polling */
     for(i = 0; i < nfds; i++) {
         fds[i].revents = 0;
@@ -1192,29 +1203,35 @@ LIBSSH2_API int libssh2_poll(LIBSSH2_POLLFD *fds, unsigned int nfds, long timeou
             case LIBSSH2_POLLFD_SOCKET:
                 if (fds[i].events & LIBSSH2_POLLFD_POLLIN) {
                     FD_SET(fds[i].fd.socket, &rfds);
-                    if (fds[i].fd.socket > maxfd) maxfd = fds[i].fd.socket;
+                    if (fds[i].fd.socket > maxfd)
+                      maxfd = fds[i].fd.socket;
                 }
                 if (fds[i].events & LIBSSH2_POLLFD_POLLOUT) {
                     FD_SET(fds[i].fd.socket, &wfds);
-                    if (fds[i].fd.socket > maxfd) maxfd = fds[i].fd.socket;
+                    if (fds[i].fd.socket > maxfd)
+                      maxfd = fds[i].fd.socket;
                 }
                 break;
 
             case LIBSSH2_POLLFD_CHANNEL:
                 FD_SET(fds[i].fd.channel->session->socket_fd, &rfds);
-                if (fds[i].fd.channel->session->socket_fd > maxfd) maxfd = fds[i].fd.channel->session->socket_fd;
+                if (fds[i].fd.channel->session->socket_fd > maxfd)
+                  maxfd = fds[i].fd.channel->session->socket_fd;
                 if (!session) session = fds[i].fd.channel->session;
                 break;
 
             case LIBSSH2_POLLFD_LISTENER:
                 FD_SET(fds[i].fd.listener->session->socket_fd, &rfds);
-                if (fds[i].fd.listener->session->socket_fd > maxfd) maxfd = fds[i].fd.listener->session->socket_fd;
+                if (fds[i].fd.listener->session->socket_fd > maxfd)
+                  maxfd = fds[i].fd.listener->session->socket_fd;
                 if (!session) session = fds[i].fd.listener->session;
                 break;
 
             default:
-                if (session) libssh2_error(session, LIBSSH2_ERROR_INVALID_POLL_TYPE,
+                if (session)
-                                           "Invalid descriptor passed to libssh2_poll()", 0);
+                  libssh2_error(session, LIBSSH2_ERROR_INVALID_POLL_TYPE,
+                                "Invalid descriptor passed to libssh2_poll()",
+                                0);
                 return -1;
         }
     }