gl/lseek.c

   1 /* An lseek() function that detects pipes.
   2    Copyright (C) 2007, 2009-2012 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 3, 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, see <http://www.gnu.org/licenses/>.  */
  16
  17 #include <config.h>
  18
  19 /* Specification.  */
  20 #include <unistd.h>
  21
  22 #if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
  23 /* Windows platforms.  */
  24 /* Get GetFileType.  */
  25 # include <windows.h>
  26 /* Get _get_osfhandle.  */
  27 # include "msvc-nothrow.h"
  28 #else
  29 # include <sys/stat.h>
  30 #endif
  31 #include <errno.h>
  32
  33 #undef lseek
  34
  35 off_t
  36 rpl_lseek (int fd, off_t offset, int whence)
  37 {
  38 #if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
  39   /* mingw lseek mistakenly succeeds on pipes, sockets, and terminals.  */
  40   HANDLE h = (HANDLE) _get_osfhandle (fd);
  41   if (h == INVALID_HANDLE_VALUE)
  42     {
  43       errno = EBADF;
  44       return -1;
  45     }
  46   if (GetFileType (h) != FILE_TYPE_DISK)
  47     {
  48       errno = ESPIPE;
  49       return -1;
  50     }
  51 #else
  52   /* BeOS lseek mistakenly succeeds on pipes...  */
  53   struct stat statbuf;
  54   if (fstat (fd, &statbuf) < 0)
  55     return -1;
  56   if (!S_ISREG (statbuf.st_mode))
  57     {
  58       errno = ESPIPE;
  59       return -1;
  60     }
  61 #endif
  62 #if _GL_WINDOWS_64_BIT_OFF_T
  63   return _lseeki64 (fd, offset, whence);
  64 #else
  65   return lseek (fd, offset, whence);
  66 #endif
  67 }