Merge commit 'a39d4083cab589d7cd6a13e8a4b8db8875261d75'

[gnulib.git] / m4 / popen.m4

diff --git a/m4/popen.m4 b/m4/popen.m4
index 76fd6d9..7ff3597 100644 (file)
--- a/m4/popen.m4
+++ b/m4/popen.m4
@@ -1,5 +1,5 @@
-# popen.m4 serial 2
-dnl Copyright (C) 2009, 2010 Free Software Foundation, Inc.
+# popen.m4 serial 5
+dnl Copyright (C) 2009-2014 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.
@@ -7,23 +7,35 @@ dnl with or without modifications, as long as this notice is preserved.
 AC_DEFUN([gl_FUNC_POPEN],
 [
   AC_REQUIRE([gl_STDIO_H_DEFAULTS])
-  AC_CACHE_CHECK([whether popen works with closed stdin],
-    [gl_cv_func_popen_works],
-    [
-      AC_RUN_IFELSE([AC_LANG_PROGRAM([[#include <stdio.h>
-]], [FILE *child;
-     fclose (stdin);
-     fclose (stdout);
-     child = popen ("echo a", "r");
-     return !(fgetc (child) == 'a' && pclose (child) == 0);
-])], [gl_cv_func_popen_works=yes], [gl_cv_func_popen_works=no],
-     dnl For now, only cygwin 1.5 or older is known to be broken.
-     [gl_cv_func_popen_works='guessing yes'])
-  ])
-  if test "$gl_cv_func_popen_works" = no; then
-    REPLACE_POPEN=1
-    AC_LIBOBJ([popen])
-    gl_PREREQ_POPEN
+  AC_CHECK_FUNCS_ONCE([popen])
+  if test $ac_cv_func_popen = no; then
+    HAVE_POPEN=0
+  else
+    AC_CACHE_CHECK([whether popen works with closed stdin],
+      [gl_cv_func_popen_works],
+      [
+        AC_RUN_IFELSE(
+          [AC_LANG_PROGRAM(
+             [[#include <stdio.h>]],
+             [[int result = 0;
+               FILE *child;
+               fclose (stdin);
+               fclose (stdout);
+               child = popen ("echo a", "r");
+               if (fgetc (child) != 'a')
+                 result |= 1;
+               if (pclose (child) != 0)
+                 result |= 2;
+               return result;
+             ]])],
+          [gl_cv_func_popen_works=yes],
+          [gl_cv_func_popen_works=no],
+          dnl For now, only cygwin 1.5 or older is known to be broken.
+          [gl_cv_func_popen_works='guessing yes'])
+      ])
+    if test "$gl_cv_func_popen_works" = no; then
+      REPLACE_POPEN=1
+    fi
   fi
 ])