tests: improve diagnostics when write(2) fails

MinGW programs can't redirect file descriptor 9, they can only redirect
stdin, stdout and stderr.  So, improve the information in the test log.

See automake bug#10466.

* tests/parallel-tests-fd-redirect.test (baz.c, zardoz.c): Check the
return value from the write(2) call, and report detected errors.

diff --git a/tests/parallel-tests-fd-redirect.test b/tests/parallel-tests-fd-redirect.test
index 73a134e..8b16378 100755 (executable)
--- a/tests/parallel-tests-fd-redirect.test
+++ b/tests/parallel-tests-fd-redirect.test
@@ -1,5 +1,5 @@
 #! /bin/sh
-# Copyright (C) 2011 Free Software Foundation, Inc.
+# Copyright (C) 2011, 2012 Free Software Foundation, Inc.
 #
 # This program is free software; you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -65,20 +65,26 @@ END
 chmod a+x foo.sh bar
 
 cat > baz.c <<'END'
+#include <stdio.h>
 #include <unistd.h>
 int main (void)
 {
-  write (9, " bazbazbaz\n", 11);
-  return 0;
+  ssize_t res = write (9, " bazbazbaz\n", 11);
+  if (res < 0)
+    perror("write failed");
+  return res != 11;
 }
 END
 
 cat > zardoz.c <<'END'
+#include <stdio.h>
 #include <unistd.h>
 int main (void)
 {
-  write (9, " quxquxqux\n", 11);
-  return 0;
+  ssize_t res = write (9, " quxquxqux\n", 11);
+  if (res < 0)
+    perror("write failed");
+  return res != 11;
 }
 END