libbb/safe_poll.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * Utility routines.
   4  *
   5  * Copyright (C) 2007 by Denys Vlasenko <vda.linux@googlemail.com>
   6  *
   7  * Licensed under GPLv2, see file LICENSE in this source tree.
   8  */
   9 #include "libbb.h"
  10
  11 /* Wrapper which restarts poll on EINTR or ENOMEM.
  12  * On other errors does perror("poll") and returns.
  13  * Warning! May take longer than timeout_ms to return! */
  14 int FAST_FUNC safe_poll(struct pollfd *ufds, nfds_t nfds, int timeout)
  15 {
  16         while (1) {
  17                 int n = poll(ufds, nfds, timeout);
  18                 if (n >= 0)
  19                         return n;
  20                 /* Make sure we inch towards completion */
  21                 if (timeout > 0)
  22                         timeout--;
  23                 /* E.g. strace causes poll to return this */
  24                 if (errno == EINTR)
  25                         continue;
  26                 /* Kernel is very low on memory. Retry. */
  27                 /* I doubt many callers would handle this correctly! */
  28                 if (errno == ENOMEM)
  29                         continue;
  30                 bb_simple_perror_msg("poll");
  31                 return n;
  32         }
  33 }