gl/lseek.c

   1 /* An lseek() function that detects pipes.
   2    Copyright (C) 2007 Free Software Foundation, Inc.
   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, or (at your option)
   7    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 along
  15    with this program; if not, write to the Free Software Foundation,
  16    Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
  17
  18 #include <config.h>
  19
  20 /* Specification.  */
  21 #include <unistd.h>
  22
  23 #if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
  24 /* Windows platforms.  */
  25 /* Get GetFileType.  */
  26 # include <windows.h>
  27 #else
  28 # include <sys/stat.h>
  29 #endif
  30 #include <errno.h>
  31
  32 #undef lseek
  33
  34 off_t
  35 rpl_lseek (int fd, off_t offset, int whence)
  36 {
  37 #if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
  38   /* mingw lseek mistakenly succeeds on pipes, sockets, and terminals.  */
  39   HANDLE h = (HANDLE) _get_osfhandle (fd);
  40   if (h == INVALID_HANDLE_VALUE)
  41     {
  42       errno = EBADF;
  43       return -1;
  44     }
  45   if (GetFileType (h) != FILE_TYPE_DISK)
  46     {
  47       errno = ESPIPE;
  48       return -1;
  49     }
  50 #else
  51   /* BeOS lseek mistakenly succeeds on pipes...  */
  52   struct stat statbuf;
  53   if (fstat (fd, &statbuf) < 0)
  54     return -1;
  55   if (!S_ISREG (statbuf.st_mode))
  56     {
  57       errno = ESPIPE;
  58       return -1;
  59     }
  60 #endif
  61   return lseek (fd, offset, whence);
  62 }