Line data    Source code

       1             : /* input_avail.c -- check whether or not data is available for reading on a
       2             :                     specified file descriptor. */
       3             : 
       4             : /* Copyright (C) 2008,2009 Free Software Foundation, Inc.
       5             : 
       6             :    This file is part of GNU Bash, the Bourne Again SHell.
       7             : 
       8             :    Bash is free software: you can redistribute it and/or modify
       9             :    it under the terms of the GNU General Public License as published by
      10             :    the Free Software Foundation, either version 3 of the License, or
      11             :    (at your option) any later version.
      12             : 
      13             :    Bash is distributed in the hope that it will be useful,
      14             :    but WITHOUT ANY WARRANTY; without even the implied warranty of
      15             :    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      16             :    GNU General Public License for more details.
      17             : 
      18             :    You should have received a copy of the GNU General Public License
      19             :    along with Bash.  If not, see <http://www.gnu.org/licenses/>.
      20             : */
      21             : 
      22             : #if defined (__TANDEM)
      23             : #  include <floss.h>
      24             : #endif
      25             : 
      26             : #if defined (HAVE_CONFIG_H)
      27             : #  include <config.h>
      28             : #endif
      29             : 
      30             : #include <sys/types.h>
      31             : #include <fcntl.h>
      32             : #if defined (HAVE_SYS_FILE_H)
      33             : #  include <sys/file.h>
      34             : #endif /* HAVE_SYS_FILE_H */
      35             : 
      36             : #if defined (HAVE_UNISTD_H)
      37             : #  include <unistd.h>
      38             : #endif /* HAVE_UNISTD_H */
      39             : 
      40             : #include "bashansi.h"
      41             : 
      42             : #include "posixselect.h"
      43             : 
      44             : #if defined (FIONREAD_IN_SYS_IOCTL)
      45             : #  include <sys/ioctl.h>
      46             : #endif
      47             : 
      48             : #include <stdio.h>
      49             : #include <errno.h>
      50             : 
      51             : #if !defined (errno)
      52             : extern int errno;
      53             : #endif /* !errno */
      54             : 
      55             : #if !defined (O_NDELAY) && defined (O_NONBLOCK)
      56             : #  define O_NDELAY O_NONBLOCK   /* Posix style */
      57             : #endif
      58             : 
      59             : /* Return >= 1 if select/FIONREAD indicates data available for reading on
      60             :    file descriptor FD; 0 if no data available.  Return -1 on error. */
      61             : int
      62           0 : input_avail (fd)
      63             :      int fd;
      64             : {
      65           0 :   int result, chars_avail;
      66             : #if defined(HAVE_SELECT)
      67           0 :   fd_set readfds, exceptfds;
      68           0 :   struct timeval timeout;
      69             : #endif
      70             : 
      71           0 :   if (fd < 0)
      72             :     return -1;
      73             : 
      74           0 :   chars_avail = 0;
      75             : 
      76             : #if defined (HAVE_SELECT)
      77           0 :   FD_ZERO (&readfds);
      78           0 :   FD_ZERO (&exceptfds);
      79           0 :   FD_SET (fd, &readfds);
      80           0 :   FD_SET (fd, &exceptfds);
      81           0 :   timeout.tv_sec = 0;
      82           0 :   timeout.tv_usec = 0;
      83           0 :   result = select (fd + 1, &readfds, (fd_set *)NULL, &exceptfds, &timeout);
      84           0 :   return ((result <= 0) ? 0 : 1);
      85             : 
      86             : #endif
      87             : 
      88             :   result = -1;
      89             : #if defined (FIONREAD)
      90             :   errno = 0;
      91             :   result = ioctl (fd, FIONREAD, &chars_avail);
      92             :   if (result == -1 && errno == EIO)
      93             :     return -1;
      94             :   return (chars_avail);
      95             : #endif
      96             : 
      97             :   return 0;
      98             : }