Line data    Source code

       1             : /*
       2             :     Authors:
       3             :         Jan Cholasta <jcholast@redhat.com>
       4             : 
       5             :     Copyright (C) 2012 Red Hat
       6             : 
       7             :     This program is free software; you can redistribute it and/or modify
       8             :     it under the terms of the GNU General Public License as published by
       9             :     the Free Software Foundation; either version 3 of the License, or
      10             :     (at your option) any later version.
      11             : 
      12             :     This program is distributed in the hope that it will be useful,
      13             :     but WITHOUT ANY WARRANTY; without even the implied warranty of
      14             :     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      15             :     GNU General Public License for more details.
      16             : 
      17             :     You should have received a copy of the GNU General Public License
      18             :     along with this program.  If not, see <http://www.gnu.org/licenses/>.
      19             : */
      20             : 
      21             : #include "util/atomic_io.h"
      22             : 
      23             : /* based on code from libssh <http://www.libssh.org> */
      24         960 : ssize_t sss_atomic_io_s(int fd, void *buf, size_t n, bool do_read)
      25             : {
      26         960 :     char *b = buf;
      27         960 :     size_t pos = 0;
      28             :     ssize_t res;
      29             :     struct pollfd pfd;
      30             : 
      31         960 :     pfd.fd = fd;
      32         960 :     pfd.events = do_read ? POLLIN : POLLOUT;
      33             : 
      34        2871 :     while (n > pos) {
      35        1858 :         if (do_read) {
      36        1845 :             res = read(fd, b + pos, n - pos);
      37             :         } else {
      38          13 :             res = write(fd, b + pos, n - pos);
      39             :         }
      40        1858 :         switch (res) {
      41             :         case -1:
      42           8 :             if (errno == EINTR) {
      43           0 :                 continue;
      44             :             }
      45           8 :             if (errno == EAGAIN || errno == EWOULDBLOCK) {
      46           8 :                 (void) poll(&pfd, 1, -1);
      47           8 :                 continue;
      48             :             }
      49           0 :             return -1;
      50             :         case 0:
      51             :             /* read returns 0 on end-of-file */
      52         907 :             errno = do_read ? 0 : EPIPE;
      53         907 :             return pos;
      54             :         default:
      55         943 :             pos += (size_t) res;
      56             :         }
      57             :     }
      58             : 
      59          53 :     return pos;
      60             : }