When not cross-compiling, perform a real runtime test.

diff --git a/ChangeLog b/ChangeLog
index 253ae37..807c572 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2007-05-28  Bruno Haible  <bruno@clisp.org>
+
+       * m4/lseek.m4 (gl_FUNC_LSEEK): When not cross-compiling, perform a real
+       runtime test.
+
 2007-05-28  Eric Blake  <ebb9@byu.net>
 
        Improve lseek module.

diff --git a/m4/lseek.m4 b/m4/lseek.m4
index 075c2f4..4877bfd 100644 (file)
--- a/m4/lseek.m4
+++ b/m4/lseek.m4
@@ -1,4 +1,4 @@
-# lseek.m4 serial 1
+# lseek.m4 serial 2
 dnl Copyright (C) 2007 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -9,12 +9,32 @@ AC_DEFUN([gl_FUNC_LSEEK],
   AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
   AC_REQUIRE([AC_PROG_CC])
   AC_CACHE_CHECK([whether lseek detects pipes], [gl_cv_func_lseek_pipe],
-    [AC_COMPILE_IFELSE([AC_LANG_PROGRAM([#include <unistd.h>],
-[#if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
+    [if test $cross_compiling = no; then
+       AC_LINK_IFELSE([
+#include <sys/types.h> /* for off_t */
+#include <stdio.h> /* for SEEK_CUR */
+#include <unistd.h>
+int main ()
+{
+  /* Exit with success only if stdin is seekable.  */
+  return lseek (0, (off_t)0, SEEK_CUR) < 0;
+}],
+         [if test -s conftest$ac_exeext \
+             && ./conftest$ac_exeext < conftest.$ac_ext \
+             && { echo hi | ./conftest$ac_exeext; test $? = 1; }; then
+            gl_cv_func_lseek_pipe=yes
+          else
+            gl_cv_func_lseek_pipe=no
+          fi],
+         [gl_cv_func_lseek_pipe=no])
+     else
+       AC_LINK_IFELSE([
+#if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
 /* mingw mistakenly returns 0 when trying to seek on pipes.  */
   Choke me.
-#endif])],
-      [gl_cv_func_lseek_pipe=yes], [gl_cv_func_lseek_pipe=no])])
+#endif],
+         [gl_cv_func_lseek_pipe=yes], [gl_cv_func_lseek_pipe=no])
+     fi])
   if test $gl_cv_func_lseek_pipe = no; then
     gl_REPLACE_LSEEK
   fi