Simplify and document.

[gnulib.git] / m4 / ftruncate.m4

diff --git a/m4/ftruncate.m4 b/m4/ftruncate.m4
index d25c17e..e71e99b 100644 (file)
--- a/m4/ftruncate.m4
+++ b/m4/ftruncate.m4
@@ -1,23 +1,34 @@
-#serial 7
+#serial 10
 
 # See if we need to emulate a missing ftruncate function using fcntl or chsize.
 
-# Copyright (C) 2000, 2001, 2003, 2004 Free Software Foundation, Inc.
+# Copyright (C) 2000, 2001, 2003-2006 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.
 
+# FIXME: remove this macro, along with all uses of HAVE_FTRUNCATE in 2007,
+# if the check below provokes no reports.
+
 AC_DEFUN([gl_FUNC_FTRUNCATE],
 [
   AC_REPLACE_FUNCS(ftruncate)
   if test $ac_cv_func_ftruncate = no; then
     gl_PREREQ_FTRUNCATE
+    # If someone lacks ftruncate, make configure fail, and request
+    # a bug report to inform us about it.
+    if test x"$SKIP_FTRUNCATE_CHECK" != xyes; then
+      AC_MSG_FAILURE([Your system lacks the ftruncate function.
+         Please report this, along with the output of "uname -a", to the
+         bug-coreutils@gnu.org mailing list.  To continue past this point,
+         rerun configure with SKIP_FTRUNCATE_CHECK=yes.
+         E.g., ./configure SKIP_FTRUNCATE_CHECK=yes])
+    fi
   fi
 ])
 
 # Prerequisites of lib/ftruncate.c.
 AC_DEFUN([gl_PREREQ_FTRUNCATE],
 [
-  AC_CHECK_HEADERS_ONCE(unistd.h)
   AC_CHECK_FUNCS(chsize)
 ])