39b18196f
Denys Vlasenko
2019-01-06
Subject
telnetd: fix bad interaction with vhangup() from login
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networking/telnetd.c+16 -2
| @@ -865,11 +865,25 @@ int telnetd_main(int argc UNUSED_PARAM, char **argv) | |
| skip3: | |
| if (/*ts->size2 < BUFSIZE &&*/ FD_ISSET(ts->ptyfd, &rdfdset)) { | |
| /* Read from pty to buffer 2 */ | |
| + | int eio = 0; |
| + | read_pty: |
| count = MIN(BUFSIZE - ts->rdidx2, BUFSIZE - ts->size2); | |
| count = safe_read(ts->ptyfd, TS_BUF2(ts) + ts->rdidx2, count); | |
| if (count <= 0) { | |
| - | if (count < 0 && errno == EAGAIN) |
| - | goto skip4; |
| + | if (count < 0) { |
| + | if (errno == EAGAIN) |
| + | goto skip4; |
| + | /* login process might call vhangup(), |
| + | * which causes intermittent EIOs on read above |
| + | * (observed on kernel 4.12.0). Try up to 10 ms. |
| + | */ |
| + | if (errno == EIO && eio < 10) { |
| + | eio++; |
| + | //bb_error_msg("EIO pty %u", eio); |
| + | usleep(1000); |
| + | goto read_pty; |
| + | } |
| + | } |
| goto kill_session; | |
| } | |
| ts->size2 += count; | |