getloadavg: set errno

* lib/getloadavg.c: Set errno when returning -1.  If no other
error number looks appropriate, set it to ENOSYS if the getloadavg
looks like it can't possibly ever work, ENOTSUP otherwise.
Suggested by Bruno Haible in
<http://lists.gnu.org/archive/html/bug-gnulib/2011-02/msg00187.html>.

getloadavg: trim unused parts and speed up 'configure'
* NEWS: Document this.
* lib/getloadavg.c: Ignore HAVE_GETLOADAVG; this file is now
always compiled if getloadavg is absent.
Move test code to ...
* tests/test-getloadavg.c: New file, containing previous
contents of test from lib/getloadavg.c.  It also contains
suggestions by Bruno Haible in
<http://lists.gnu.org/archive/html/bug-gnulib/2011-02/msg00186.html>.
* modules/getloadavg-tests: New file.
* m4/getloadavg.m4 (gl_GETLOADAVG): Do not check for getloadavg twice.
Do tests in the same order as they're needed for getloadavg.c.
Omit setgid-related tests that generate symbols KMEM_GROUP,
NEET_SETGID, GETLOADAVG_PRIVILEGED; nobody seems to use those any more.
Do only the tests that are needed to see whether the system has
getloadavg, moving the other tests into ...
(gl_PREREQ_GETLOADAVG): ... here.  Do not define obsolete symbol
NLIST_NAME_UNION; nobody should be using it.  Do not define
symbols C_GETLOADAVG and HAVE_GETLOADAVG; they're no longer
relevant, as the user of this module shouldn't care how getloadavg
is implemented.

1 files changed, 75 insertions, 0 deletions

diff --git a/tests/test-getloadavg.c b/tests/test-getloadavg.c
new file mode 100644
index 0000000000..f9b4a79b57
--- /dev/null
+++ b/tests/test-getloadavg.c
@@ -0,0 +1,75 @@
+/* Test of getting load average.
+   Copyright (C) 2011 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
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#include <config.h>
+
+#include <stdlib.h>
+
+#include "signature.h"
+SIGNATURE_CHECK (getloadavg, int, (double [], int));
+
+#include <errno.h>
+#include <stdio.h>
+#include <unistd.h>
+
+static void
+check_avg (int minutes, double avg, int printit)
+{
+  if (printit)
+    printf ("%d-minute: %f  ", minutes, avg);
+  if (avg < 0 || avg != avg)
+    exit (minutes);
+}
+
+/* This program can also be used as a manual test, by invoking it with
+   an argument; it then prints the load average.  If the argument is
+   nonzero, the manual test repeats forever, sleeping for the stated
+   interval between each iteration.  */
+int
+main (int argc, char **argv)
+{
+  int naptime = 0;
+
+  if (argc > 1)
+    naptime = atoi (argv[1]);
+
+  while (1)
+    {
+      double avg[3];
+      int loads = getloadavg (avg, 3);
+      if (loads == -1)
+        {
+          if (! (errno == ENOSYS || errno == ENOTSUP))
+            return 1;
+          perror ("Skipping test; load average not supported");
+          return 77;
+        }
+      if (loads > 0)
+        check_avg (1, avg[0], argc > 1);
+      if (loads > 1)
+        check_avg (5, avg[1], argc > 1);
+      if (loads > 2)
+        check_avg (15, avg[1], argc > 1);
+      if (loads > 0 && argc > 1)
+        putchar ('\n');
+
+      if (naptime == 0)
+        break;
+      sleep (naptime);
+    }
+
+  return 0;
+}