nc_bloaty: use poll() instead of select()

function                                             old     new   delta
readwrite                                            829     715    -114

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 24 insertions, 31 deletions

diff --git a/networking/nc_bloaty.c b/networking/nc_bloaty.c
index 192e42fe5..f8c375362 100644
--- a/networking/nc_bloaty.c
+++ b/networking/nc_bloaty.c
@@ -582,11 +582,10 @@ void oprint(int direction, unsigned char *p, unsigned bc);
 #endif
 
 /* readwrite:
- handle stdin/stdout/network I/O.  Bwahaha!! -- the select loop from hell.
+ handle stdin/stdout/network I/O.  Bwahaha!! -- the i/o loop from hell.
  In this instance, return what might become our exit status. */
 static int readwrite(void)
 {
-        int rr;
         char *zp = zp; /* gcc */  /* stdin buf ptr */
         char *np = np;            /* net-in buf ptr */
         unsigned rzleft;
@@ -594,45 +593,41 @@ static int readwrite(void)
         unsigned netretry;              /* net-read retry counter */
         unsigned fds_open;
 
-        /* if you don't have all this FD_* macro hair in sys/types.h, you'll have to
-         either find it or do your own bit-bashing: *ding1 |= (1 << fd), etc... */
-        fd_set ding1;                   /* for select loop */
-        fd_set ding2;
-        FD_ZERO(&ding1);
-        FD_SET(netfd, &ding1);
-        FD_SET(STDIN_FILENO, &ding1);
-        fds_open = 2;
+        struct pollfd pfds[2];
+        pfds[0].fd = STDIN_FILENO;
+        pfds[0].events = POLLIN;
+        pfds[1].fd = netfd;
+        pfds[1].events = POLLIN;
 
+        fds_open = 2;
         netretry = 2;
         rzleft = rnleft = 0;
         if (o_interval)
                 sleep(o_interval);                /* pause *before* sending stuff, too */
 
-        /* and now the big ol' select shoveling loop ... */
+        /* and now the big ol' shoveling loop ... */
         /* nc 1.10 has "while (FD_ISSET(netfd)" here */
         while (fds_open) {
+                int rr;
+                int poll_tmout_ms;
                 unsigned wretry = 8200;               /* net-write sanity counter */
 
-                ding2 = ding1;                        /* FD_COPY ain't portable... */
-        /* some systems, notably linux, crap into their select timers on return, so
-         we create a expendable copy and give *that* to select.  */
+                poll_tmout_ms = -1;
                 if (o_wait) {
-                        struct timeval tmp_timer;
-                        tmp_timer.tv_sec = o_wait;
-                        tmp_timer.tv_usec = 0;
-                /* highest possible fd is netfd (3) */
-                        rr = select(netfd+1, &ding2, NULL, NULL, &tmp_timer);
-                } else
-                        rr = select(netfd+1, &ding2, NULL, NULL, NULL);
+                        poll_tmout_ms = INT_MAX;
+                        if (o_wait < INT_MAX / 1000)
+                                poll_tmout_ms = o_wait * 1000;
+                }
+                rr = poll(pfds, 2, poll_tmout_ms);
                 if (rr < 0 && errno != EINTR) {                /* might have gotten ^Zed, etc */
-                        holler_perror("select");
+                        holler_perror("poll");
                         close(netfd);
                         return 1;
                 }
         /* if we have a timeout AND stdin is closed AND we haven't heard anything
          from the net during that time, assume it's dead and close it too. */
                 if (rr == 0) {
-                        if (!FD_ISSET(STDIN_FILENO, &ding1)) {
+                        if (!pfds[0].revents) {
                                 netretry--;                        /* we actually try a coupla times. */
                                 if (!netretry) {
                                         if (o_verbose > 1)         /* normally we don't care */
@@ -641,19 +636,17 @@ static int readwrite(void)
                                         return 0;                  /* not an error! */
                                 }
                         }
-                } /* select timeout */
-        /* xxx: should we check the exception fds too?  The read fds seem to give
-         us the right info, and none of the examples I found bothered. */
+                } /* timeout */
 
         /* Ding!!  Something arrived, go check all the incoming hoppers, net first */
-                if (FD_ISSET(netfd, &ding2)) {                /* net: ding! */
+                if (pfds[1].revents) {                /* net: ding! */
                         rr = read(netfd, bigbuf_net, BIGSIZ);
                         if (rr <= 0) {
                                 if (rr < 0 && o_verbose > 1) {
                                         /* nc 1.10 doesn't do this */
                                         bb_perror_msg("net read");
                                 }
-                                FD_CLR(netfd, &ding1);                /* net closed */
+                                pfds[1].fd = -1;                   /* don't poll for netfd anymore */
                                 fds_open--;
                                 rzleft = 0;                        /* can't write anymore: broken pipe */
                         } else {
@@ -669,12 +662,12 @@ Debug("got %d from the net, errno %d", rr, errno);
                         goto shovel;
 
         /* okay, suck more stdin */
-                if (FD_ISSET(STDIN_FILENO, &ding2)) {                /* stdin: ding! */
+                if (pfds[0].revents) {                /* stdin: ding! */
                         rr = read(STDIN_FILENO, bigbuf_in, BIGSIZ);
         /* Considered making reads here smaller for UDP mode, but 8192-byte
          mobygrams are kinda fun and exercise the reassembler. */
                         if (rr <= 0) {                        /* at end, or fukt, or ... */
-                                FD_CLR(STDIN_FILENO, &ding1); /* disable stdin */
+                                pfds[0].fd = -1;              /* disable stdin */
                                 /*close(STDIN_FILENO); - not really necessary */
                                 /* Let peer know we have no more data */
                                 /* nc 1.10 doesn't do this: */
@@ -718,7 +711,7 @@ Debug("wrote %d to net, errno %d", rr, errno);
                 } /* rzleft */
                 if (o_interval) {                        /* cycle between slow lines, or ... */
                         sleep(o_interval);
-                        continue;                        /* ...with hairy select loop... */
+                        continue;                        /* ...with hairy loop... */
                 }
                 if (rzleft || rnleft) {                  /* shovel that shit till they ain't */
                         wretry--;                        /* none left, and get another load */