flux-config: add new command

flux-config provides an interface to the flux config file.

This uses libflux/fconfig.[ch], which leverages ZPL format as
used by the zconfig class in czmq.  ZPL is documented in
rfc.zeromq.org/spec:4/ZPL.

src/cmd/Makefile.am

@@ -49,7 +49,8 @@ fluxcmd_PROGRAMS = \
 	flux-comms \
 	flux-comms-stats \
 	flux-kvs \
-	flux-start
+	flux-start \
+	flux-config
 
 flux_zio_LDADD = \
 	$(top_builddir)/src/common/libzio/libzio.la \

src/cmd/flux-config.c

@@ -0,0 +1,183 @@
+/*****************************************************************************\
+ *  Copyright (c) 2014 Lawrence Livermore National Security, LLC.  Produced at
+ *  the Lawrence Livermore National Laboratory (cf, AUTHORS, DISCLAIMER.LLNS).
+ *  LLNL-CODE-658032 All rights reserved.
+ *
+ *  This file is part of the Flux resource manager framework.
+ *  For details, see https://github.com/flux-framework.
+ *
+ *  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 2 of the license, or (at your option)
+ *  any later version.
+ *
+ *  Flux 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 terms and conditions of 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, write to the Free Software Foundation, Inc.,
+ *  59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
+ *  See also:  http://www.gnu.org/licenses/
+\*****************************************************************************/
+
+#if HAVE_CONFIG_H
+#include "config.h"
+#endif
+#include <stdio.h>
+#include <sys/types.h>
+#include <getopt.h>
+#include <pwd.h>
+#include <flux/core.h>
+
+#include "src/common/libutil/xzmalloc.h"
+#include "src/common/libutil/argv.h"
+#include "src/common/libutil/log.h"
+
+void config_dump (const char *config_file, int ac, char **av);
+void config_get (const char *config_file, int ac, char **av);
+void config_put (const char *config_file, int ac, char **av);
+
+#define OPTIONS "hc:"
+static const struct option longopts[] = {
+    {"help",       no_argument,        0, 'h'},
+    {"config",     required_argument,  0, 'c'},
+    { 0, 0, 0, 0 },
+};
+
+void usage (void)
+{
+    fprintf (stderr,
+"Usage: flux-config [-c FILE] dump [key]\n"
+"       flux-config [-c FILE] get [key]\n"
+"       flux-config [-c FILE] put key=val\n"
+);
+    exit (1);
+}
+
+int main (int argc, char *argv[])
+{
+    int ch;
+    char *config_file = NULL;
+    char *cmd;
+
+    log_init ("flux-config");
+
+    while ((ch = getopt_long (argc, argv, OPTIONS, longopts, NULL)) != -1) {
+        switch (ch) {
+            case 'h': /* --help */
+                usage ();
+                break;
+            case 'c': /* --config FILE */
+                config_file = optarg;
+                break;
+            default:
+                usage ();
+                break;
+        }
+    }
+    if (optind == argc)
+        usage ();
+    cmd = argv[optind++];
+    if (!strcmp (cmd, "get"))
+        config_get (config_file, argc - optind, argv + optind);
+    else if (!strcmp (cmd, "dump"))
+        config_dump (config_file, argc - optind, argv + optind);
+    else if (!strcmp (cmd, "put"))
+        config_put (config_file, argc - optind, argv + optind);
+    else
+        usage ();
+
+    exit (0);
+}
+
+static char *mktab (int level)
+{
+    const int tabspace = 4;
+    char *tab = xzmalloc (level*tabspace + 1);
+    memset (tab, ' ', level*tabspace);
+    return tab;
+}
+
+void zdump (zconfig_t *z, int level)
+{
+    char *tab = mktab (level);
+    char *key = zconfig_name (z);
+    char *val = zconfig_value (z);
+    zconfig_t *child = zconfig_child (z);
+
+    if (child) {
+        printf ("%s%s:\n", tab, key);
+        do {
+            zdump (child, level + 1);
+            child = zconfig_next (child);
+        } while (child);
+    } else if (val)
+        printf ("%s%s = \"%s\"\n", tab, key, val);
+    else
+        printf ("%s%s = nil\n", tab, key);
+
+    free (tab);
+}
+
+void config_dump (const char *config_file, int ac, char **av)
+{
+    zconfig_t *root, *z;
+    char *key = "/";
+
+    if (ac > 1)
+        msg_exit ("dump accepts zero or one argument");
+    if (ac == 1)
+        key = av[0];
+    root = flux_config_load (config_file, true);
+    if (!strcmp (key, "/") || !strcmp (key, "root")) {
+        z = zconfig_child (root);
+        while (z) {
+            zdump (z, 0);
+            z = zconfig_next (z);
+        }
+    } else {
+        if (!(z = zconfig_locate (root, key)))
+            errn_exit (ENOENT, "%s", key);
+        zdump (z, 0);
+    }
+    zconfig_destroy (&root);
+}
+
+void config_get (const char *config_file, int ac, char **av)
+{
+    zconfig_t *root, *z;
+    char *key, *val;
+
+    if (ac != 1)
+        msg_exit ("get accepts one argument");
+    key = av[0];
+    root = flux_config_load (config_file, true);
+    if (!(z = zconfig_locate (root, key)) || !(val = zconfig_value (z))
+                                          || strlen (val) == 0)
+        errn_exit (ENOENT, "%s", key);
+    printf ("%s\n", val);
+    zconfig_destroy (&root);
+}
+
+void config_put (const char *config_file, int ac, char **av)
+{
+    zconfig_t *root;
+    char *key, *val;
+
+    if (ac != 1)
+        msg_exit ("put accepts one key[=val] argument");
+    key = xstrdup (av[0]);
+    if ((val = strchr (key, '=')))
+        *val++ = '\0';
+    root = flux_config_load (config_file, false);
+    zconfig_put (root, key, val);
+    flux_config_save (config_file, root);
+    zconfig_destroy (&root);
+    free (key);
+}
+
+/*
+ * vi:tabstop=4 shiftwidth=4 expandtab
+ */