# serial 20

# See if we need to emulate a missing ftruncate function using chsize.

# Copyright (C) 2000-2001, 2003-2007, 2009-2020 Free Software Foundation, Inc.

# This file is free software; the Free Software Foundation

# gives unlimited permission to copy and/or distribute it,

# with or without modifications, as long as this notice is preserved.

AC_DEFUN([gl_FUNC_FTRUNCATE],

[

  AC_REQUIRE([gl_UNISTD_H_DEFAULTS])

  AC_CHECK_FUNCS_ONCE([ftruncate])

  if test $ac_cv_func_ftruncate = yes; then

    m4_ifdef([gl_LARGEFILE], [

      AC_REQUIRE([AC_CANONICAL_HOST])

      case "$host_os" in

        mingw*)

          dnl Native Windows, and Large File Support is requested.

          dnl The MSVCRT _chsize() function only accepts a 32-bit file size,

          dnl and the mingw64 ftruncate64() function is unreliable (it may

          dnl delete the file, see

          dnl <https://web.archive.org/web/20160425005423/http://mingw-w64.sourcearchive.com/documentation/2.0-1/ftruncate64_8c_source.html>).

          dnl Use gnulib's ftruncate() implementation instead.

          REPLACE_FTRUNCATE=1

          ;;

      esac

    ], [

      :

    ])

  else

    HAVE_FTRUNCATE=0

  fi

])

# Prerequisites of lib/ftruncate.c.

AC_DEFUN([gl_PREREQ_FTRUNCATE],

[

  AC_CHECK_FUNCS([chsize])

])