X-Git-Url: http://erislabs.net/gitweb/?a=blobdiff_plain;f=m4%2Fftruncate.m4;h=4f2dafbab4c6939ba4cbd905a3d0aa1a2ed3c415;hb=533101a268dc5015a140ff4695d8eeb04fbe57b6;hp=473fde210f602b95d9e0cb36ca4862bcf531f827;hpb=a965c0038c4b72af2497d3ec44aeb4587c2478d5;p=gnulib.git

diff --git a/m4/ftruncate.m4 b/m4/ftruncate.m4
index 473fde210..4f2dafbab 100644
--- a/m4/ftruncate.m4
+++ b/m4/ftruncate.m4
@@ -1,27 +1,40 @@
-#serial 2
+# serial 20
 
-# See if we need to emulate a missing ftruncate function using fcntl.
+# See if we need to emulate a missing ftruncate function using chsize.
 
-AC_DEFUN(jm_FUNC_FTRUNCATE,
-[
-  AC_CHECK_FUNCS(ftruncate, , [ftruncate_missing=yes])
+# Copyright (C) 2000-2001, 2003-2007, 2009-2013 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.
 
-  if test "$ftruncate_missing" = yes; then
-    AC_CHECK_HEADERS(unistd.h)
-    AC_MSG_CHECKING([fcntl emulation of ftruncate])
-    AC_CACHE_VAL(fu_cv_sys_ftruncate_emulation,
-    [AC_TRY_LINK([
-#include <sys/types.h>
-#include <fcntl.h>], [
-#if !defined(F_CHSIZE) && !defined(F_FREESP)
-  chsize();
-#endif
-  ],
-      fu_cv_sys_ftruncate_emulation=yes,
-      fu_cv_sys_ftruncate_emulation=no)])
-    AC_MSG_RESULT($fu_cv_sys_ftruncate_emulation)
-    if test $fu_cv_sys_ftruncate_emulation = yes; then
-      AC_LIBOBJ([ftruncate])
-    fi
+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
   fi
 ])
+
+# Prerequisites of lib/ftruncate.c.
+AC_DEFUN([gl_PREREQ_FTRUNCATE],
+[
+  AC_CHECK_FUNCS([chsize])
+])