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 /* Get GetFileType.  The replacement lseek is only used on mingw, so
  24    this include can be unconditional.  */
  25 #include <windows.h>
  26 #include <errno.h>
  27
  28 #undef lseek
  29
  30 off_t
  31 rpl_lseek (int fd, off_t offset, int whence)
  32 {
  33   /* mingw lseek mistakenly succeeds on pipes, sockets, and terminals.  */
  34   HANDLE h = (HANDLE) _get_osfhandle (fd);
  35   if (h == INVALID_HANDLE_VALUE)
  36     {
  37       errno = EBADF;
  38       return -1;
  39     }
  40   if (GetFileType (h) != FILE_TYPE_DISK)
  41     {
  42       errno = ESPIPE;
  43       return -1;
  44     }
  45   return lseek (fd, offset, whence);
  46 }