/* An lseek() function that detects pipes.

   Copyright (C) 2007, 2009-2018 Free Software Foundation, Inc.

   This program is free software; you can redistribute it and/or modify

   it under the terms of the GNU General Public License as published by

   the Free Software Foundation; either version 3, or (at your option)

   any later version.

   This program is distributed in the hope that it will be useful,

   but WITHOUT ANY WARRANTY; without even the implied warranty of

   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License along

   with this program; if not, see <https://www.gnu.org/licenses/>.  */

#include <config.h>

/* Specification.  */

#include <unistd.h>

#if defined _WIN32 && ! defined __CYGWIN__

/* Windows platforms.  */

/* Get GetFileType.  */

# include <windows.h>

/* Get _get_osfhandle.  */

# if GNULIB_MSVC_NOTHROW

#  include "msvc-nothrow.h"

# else

#  include <io.h>

# endif

#else

# include <sys/stat.h>

#endif

#include <errno.h>

#undef lseek

off_t

rpl_lseek (int fd, off_t offset, int whence)

{

#if defined _WIN32 && ! defined __CYGWIN__

  /* mingw lseek mistakenly succeeds on pipes, sockets, and terminals.  */

  HANDLE h = (HANDLE) _get_osfhandle (fd);

  if (h == INVALID_HANDLE_VALUE)

    {

      errno = EBADF;

      return -1;

    }

  if (GetFileType (h) != FILE_TYPE_DISK)

    {

      errno = ESPIPE;

      return -1;

    }

#else

  /* BeOS lseek mistakenly succeeds on pipes...  */

  struct stat statbuf;

  if (fstat (fd, &statbuf) < 0)

    return -1;

  if (!S_ISREG (statbuf.st_mode))

    {

      errno = ESPIPE;

      return -1;

    }

#endif

#if _GL_WINDOWS_64_BIT_OFF_T

  return _lseeki64 (fd, offset, whence);

#else

  return lseek (fd, offset, whence);

#endif

}