Merge tag 'snapshot-start' into stable

[gnulib.git] / m4 / getdtablesize.m4

diff --git a/m4/getdtablesize.m4 b/m4/getdtablesize.m4
index 8f04b3b..aa523b6 100644 (file)
--- a/m4/getdtablesize.m4
+++ b/m4/getdtablesize.m4
@@ -1,5 +1,5 @@
-# getdtablesize.m4 serial 4
-dnl Copyright (C) 2008-2013 Free Software Foundation, Inc.
+# getdtablesize.m4 serial 5
+dnl Copyright (C) 2008-2014 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
@@ -7,8 +7,35 @@ dnl with or without modifications, as long as this notice is preserved.
 AC_DEFUN([gl_FUNC_GETDTABLESIZE],
 [
   AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
+  AC_REQUIRE([AC_CANONICAL_HOST])
   AC_CHECK_FUNCS_ONCE([getdtablesize])
-  if test $ac_cv_func_getdtablesize != yes; then
+  if test $ac_cv_func_getdtablesize = yes; then
+    # Cygwin 1.7.25 automatically increases the RLIMIT_NOFILE soft limit
+    # up to an unchangeable hard limit; all other platforms correctly
+    # require setrlimit before getdtablesize() can report a larger value.
+    AC_CACHE_CHECK([whether getdtablesize works],
+      [gl_cv_func_getdtablesize_works],
+      [AC_RUN_IFELSE([
+        AC_LANG_PROGRAM([[#include <unistd.h>]],
+          [int size = getdtablesize();
+           if (dup2 (0, getdtablesize()) != -1)
+             return 1;
+           if (size != getdtablesize())
+             return 2;
+          ])],
+        [gl_cv_func_getdtablesize_works=yes],
+        [gl_cv_func_getdtablesize_works=no],
+        [case "$host_os" in
+          cygwin*) # on cygwin 1.5.25, getdtablesize() automatically grows
+            gl_cv_func_getdtablesize_works="guessing no" ;;
+          *) gl_cv_func_getdtablesize_works="guessing yes" ;;
+         esac])
+      ])
+    case "$gl_cv_func_getdtablesize_works" in
+      *yes) ;;
+      *) REPLACE_GETDTABLESIZE=1 ;;
+    esac
+  else
     HAVE_GETDTABLESIZE=0
   fi
 ])