Add tb_poll_fds() to obtain file descriptors for polling

src/python/termboxmodule.pyx

@@ -3,6 +3,8 @@
 This is a binding module for termbox library.
 """
 
+from libc.stdlib cimport malloc, free
+
 include "termboxconfig.pyx"
 
 ## No unichr in python3, use chr instead.
@@ -36,6 +38,7 @@ cdef extern from "../termbox.h":
 	int tb_select_output_mode(int mode)
 	int tb_peek_event(tb_event *event, int timeout) nogil
 	int tb_poll_event(tb_event *event) nogil
+	int tb_poll_fds(int *fds, int fds_size)
 
 class TermboxException(Exception):
 	def __init__(self, msg):
@@ -284,3 +287,16 @@ cdef class Termbox:
 		else:
 			uch = None
 		return (e.type, uch, e.key, e.mod, e.w, e.h, e.x, e.y)
+
+	def poll_fds(self):
+		"""Returns a list of file descriptors that can be polled to see when an event has arrived
+		"""
+		cdef size_t fds_count;
+		cdef int *fds;
+		try:
+			fds_count = tb_poll_fds(NULL, 0)
+			fds = <int *> malloc(fds_count * sizeof(int))
+			tb_poll_fds(fds, fds_count)
+			return [fd for fd in fds[:fds_count]]
+		finally:
+			free(fds)

src/termbox.c

@@ -296,6 +296,19 @@ int tb_peek_event(struct tb_event *event, int timeout)
 	return wait_fill_event(event, &tv);
 }
 
+size_t tb_poll_fds(int *fds, size_t fds_size)
+{
+	if (fds != NULL) {
+		if (fds_size >= 1) {
+			fds[0] = inout;
+		}
+		if (fds_size >= 2) {
+			fds[1] = winch_fds[0];
+		}
+	}
+	return 2;
+}
+
 int tb_width(void)
 {
 	return termw;

src/termbox.h

@@ -1,6 +1,7 @@
 #pragma once
 
 #include <stdint.h>
+#include <stddef.h>
 
 /* for shared objects */
 #if __GNUC__ >= 4
@@ -309,6 +310,15 @@ SO_IMPORT int tb_peek_event(struct tb_event *event, int timeout);
  */
 SO_IMPORT int tb_poll_event(struct tb_event *event);
 
+
+/* Obtains a list of internal file descriptors which can be watched for events.
+ * This can be used to integrate termbox into fd-based event loops.
+ * If fds is not NULL, up to fds_size file descriptors are stored there.
+ * Returns the number of available file descriptors, which
+ * may be more or less than fds_size.
+*/
+SO_IMPORT size_t tb_poll_fds(int *fds, size_t fds_size);
+
 /* Utility utf8 functions. */
 #define TB_EOF -1
 SO_IMPORT int tb_utf8_char_length(char c);