Add ssh_get_poll_flags()

For integration with an external mainloop, we need to know how to
replicate libssh's internal poll() calls.  We originally through
ssh_get_status() was that API, but it's not really - those flags only
get updated from the *result* of a poll(), where what we really need
is to know how libssh would *start* a poll().

Reviewed-by: Andreas Schneider <asn@cryptomilk.org>

include/libssh/libssh.h

@@ -429,6 +429,7 @@ SSH_DEPRECATED LIBSSH_API int ssh_get_pubkey_hash(ssh_session session, unsigned
 LIBSSH_API int ssh_get_random(void *where,int len,int strong);
 LIBSSH_API int ssh_get_version(ssh_session session);
 LIBSSH_API int ssh_get_status(ssh_session session);
+LIBSSH_API int ssh_get_poll_flags(ssh_session session);
 LIBSSH_API int ssh_init(void);
 LIBSSH_API int ssh_is_blocking(ssh_session session);
 LIBSSH_API int ssh_is_connected(ssh_session session);

include/libssh/socket.h

@@ -52,6 +52,7 @@ void ssh_socket_set_write_wontblock(ssh_socket s);
 void ssh_socket_set_read_wontblock(ssh_socket s);
 void ssh_socket_set_except(ssh_socket s);
 int ssh_socket_get_status(ssh_socket s);
+int ssh_socket_get_poll_flags(ssh_socket s);
 int ssh_socket_buffered_write_bytes(ssh_socket s);
 int ssh_socket_data_available(ssh_socket s);
 int ssh_socket_data_writable(ssh_socket s);

src/session.c

@@ -607,6 +607,25 @@ int ssh_get_status(ssh_session session) {
   return r;
 }
 
+/**
+ * @brief Get poll flags for an external mainloop
+ *
+ * @param session       The ssh session to use.
+ *
+ * @returns A bitmask including SSH_READ_PENDING or SSH_WRITE_PENDING.
+ *          For SSH_READ_PENDING, your invocation of poll() should include
+ *          POLLIN.  For SSH_WRITE_PENDING, your invocation of poll() should
+ *          include POLLOUT.
+ */
+int ssh_get_poll_flags(ssh_session session)
+{
+  if (session == NULL) {
+    return 0;
+  }
+
+  return ssh_socket_get_poll_flags (session->socket);
+}
+
 /**
  * @brief Get the disconnect message from the server.
  *

src/socket.c

@@ -710,6 +710,17 @@ int ssh_socket_get_status(ssh_socket s) {
   return r;
 }
 
+int ssh_socket_get_poll_flags(ssh_socket s) {
+  int r = 0;
+  if (s->poll_in != NULL && (ssh_poll_get_events (s->poll_in) & POLLIN) > 0) {
+    r |= SSH_READ_PENDING;
+  }
+  if (s->poll_out != NULL && (ssh_poll_get_events (s->poll_out) & POLLOUT) > 0) {
+    r |= SSH_WRITE_PENDING;
+  }
+  return r;
+}
+
 #ifdef _WIN32
 int ssh_socket_set_nonblocking(socket_t fd) {
   u_long nonblocking = 1;