94dcfd8cc
Denys Vlasenko
2017-02-17
Subject
nc_bloaty: use poll() instead of select()
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networking/nc_bloaty.c+24 -31
| @@ -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 */ | |