fd.c

   1 /*
   2  * Copyright (C) 2006 Andre Noll <maan@systemlinux.org>
   3  *
   4  *     This program is free software; you can redistribute it and/or modify
   5  *     it under the terms of the GNU General Public License as published by
   6  *     the Free Software Foundation; either version 2 of the License, or
   7  *     (at your option) any later version.
   8  *
   9  *     This program is distributed in the hope that it will be useful,
  10  *     but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  *     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  *     GNU General Public License for more details.
  13  *
  14  *     You should have received a copy of the GNU General Public License
  15  *     along with this program; if not, write to the Free Software
  16  *     Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111, USA.
  17  */
  18
  19 /** \file fd.c helper functions for file descriptor handling */
  20
  21 #include "para.h"
  22
  23 #include <sys/select.h>
  24
  25 #include "error.h"
  26 /**
  27  * check whether a file exists
  28  *
  29  * \param fn the file name
  30  *
  31  * \return Non-zero iff file exists.
  32  */
  33 int file_exists(const char *fn)
  34 {
  35         struct stat statbuf;
  36
  37         return !stat(fn, &statbuf);
  38 }
  39
  40 /**
  41  * paraslash's wrapper for select(2)
  42  *
  43  * It calls select(2) (with no exceptfds) and starts over if select() was
  44  * interrupted by a signal.
  45  *
  46  * \param n the highest-numbered descriptor in any of the two sets, plus 1
  47  * \param readfds fds that should be checked for readability
  48  * \param writefds fds that should be checked for writablility
  49  * \param timeout upper bound on the amount of time elapsed before select()
  50  *  returns
  51  *
  52  * \return The return value of the underlying select() call.
  53  *
  54  * All arguments are passed verbatim to select(2).
  55  * \sa select(2) select_tut(2)
  56  */
  57 int para_select(int n, fd_set *readfds, fd_set *writefds,
  58                 struct timeval *timeout)
  59 {
  60         int ret, err;
  61         do {
  62                 ret = select(n, readfds, writefds, NULL, timeout);
  63                 err = errno;
  64         } while (ret < 0 && err == EINTR);
  65         if (ret < 0)
  66                 PARA_CRIT_LOG("select error (%s)\n", strerror(err));
  67         return ret;
  68 }
  69
  70 /**
  71  * set a file descriptor to non-blocking mode
  72  *
  73  * \param fd The file descriptor
  74  *
  75  * \returns 1 on success, -E_F_GETFL, -E_F_SETFL, on errors.
  76  */
  77 int mark_fd_nonblock(int fd)
  78 {
  79         int flags = fcntl(fd, F_GETFL);
  80         if (flags < 0)
  81                 return -E_F_GETFL;
  82         if (fcntl(fd, F_SETFL, ((long)flags) | O_NONBLOCK) < 0)
  83                 return -E_F_SETFL;
  84         return 1;
  85 }
  86