replace select() with poll() (#270)

usage of select (3) in modern programs is typically discouraged.
this simply replaces the select call with poll (3) instead.

and since poll conveniently ignores negative fds, this also reduces
needs for some special casing.

this also handles error if they occur, while old implementation didn't.
other than the error handling, no change in functionality should occur.

main.c

@@ -29,7 +29,7 @@
 #include <errno.h>
 #include <locale.h>
 #include <signal.h>
-#include <sys/select.h>
+#include <poll.h>
 #include <sys/stat.h>
 #include <sys/wait.h>
 #include <time.h>
@@ -701,9 +701,9 @@ static void on_buttonpress(const XButtonEvent *bev)
 
 static void run(void)
 {
-	int xfd;
-	fd_set fds;
-	struct timeval timeout;
+	enum { FD_X, FD_INFO, FD_ARL, FD_CNT };
+	struct pollfd pfd[FD_CNT];
+	struct timeval timeout = {0};
 	const struct timespec ten_ms = {0, 10000000};
 	bool discard, init_thumb, load_thumb, to_set;
 	XEvent ev, nextev;
@@ -730,21 +730,16 @@ static void run(void)
 				if (!tns_load(&tns, tns.initnext, false, true))
 					remove_file(tns.initnext, false);
 			} else {
-				xfd = ConnectionNumber(win.env.dpy);
-				FD_ZERO(&fds);
-				FD_SET(xfd, &fds);
-				if (info.fd != -1) {
-					FD_SET(info.fd, &fds);
-					xfd = MAX(xfd, info.fd);
-				}
-				if (arl.fd != -1) {
-					FD_SET(arl.fd, &fds);
-					xfd = MAX(xfd, arl.fd);
-				}
-				select(xfd + 1, &fds, 0, 0, to_set ? &timeout : NULL);
-				if (info.fd != -1 && FD_ISSET(info.fd, &fds))
+				pfd[FD_X].fd = ConnectionNumber(win.env.dpy);
+				pfd[FD_INFO].fd = info.fd;
+				pfd[FD_ARL].fd = arl.fd;
+				pfd[FD_X].events = pfd[FD_INFO].events = pfd[FD_ARL].events = POLLIN;
+
+				if (poll(pfd, ARRLEN(pfd), to_set ? TV_TO_MS(&timeout) : -1) < 0)
+					continue;
+				if (pfd[FD_INFO].revents & POLLIN)
 					read_info();
-				if (arl.fd != -1 && FD_ISSET(arl.fd, &fds)) {
+				if (pfd[FD_ARL].revents & POLLIN) {
 					if (arl_handle(&arl)) {
 						/* when too fast, imlib2 can't load the image */
 						nanosleep(&ten_ms, NULL);

nsxiv.h

@@ -44,6 +44,7 @@
 
 #define TV_DIFF(t1,t2) (((t1)->tv_sec  - (t2)->tv_sec ) * 1000 + \
                         ((t1)->tv_usec - (t2)->tv_usec) / 1000)
+#define TV_TO_MS(tv)   (((tv)->tv_sec * 1000) + ((tv)->tv_usec / 1000))
 
 #define TV_SET_MSEC(tv,t) {             \
   (tv)->tv_sec  = (t) / 1000;           \