- if test "$ftruncate_missing" = yes; then
- AC_CHECK_HEADERS([unistd.h])
- AC_CHECK_FUNCS([chsize])
- AC_LIBOBJ(ftruncate)
+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 <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