allow lxc-info to get running container configuration

doc/lxc-info.sgml.in

@@ -48,9 +48,10 @@ Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
     <cmdsynopsis>
       <command>lxc-info</command>
       <arg choice="req">-n <replaceable>name</replaceable></arg>
-      <arg choice="req">-s</arg>
-      <arg choice="req">-p</arg>
-      <arg choice="req">-t <replaceable>state</replaceable></arg>
+      <arg choice="opt">-c <replaceable>KEY</replaceable></arg>
+      <arg choice="opt">-s</arg>
+      <arg choice="opt">-p</arg>
+      <arg choice="opt">-t <replaceable>state</replaceable></arg>
     </cmdsynopsis>
   </refsynopsisdiv>
 
@@ -79,6 +80,18 @@ Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 
       <varlistentry>
         <term>
+          <option><optional>-c <replaceable>KEY</replaceable></optional></option>
+        </term>
+        <listitem>
+          <para>
+            Print a configuration key from the running container. This option
+            may be given mulitple times to print out multiple key = value pairs.
+          </para>
+        </listitem>
+      </varlistentry>
+
+      <varlistentry>
+        <term>
           <option><optional>-s</optional></option>
         </term>
         <listitem>
@@ -135,6 +148,15 @@ Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
         </listitem>
       </varlistentry>
 
+      <varlistentry>
+        <term>lxc-info -n foo -c lxc.network.0.veth.pair</term>
+        <listitem>
+          <para>
+            prints the veth pair name of foo.
+          </para>
+        </listitem>
+      </varlistentry>
+
     </variablelist>
   </refsect1>
 

src/lxc/lxc_info.c

@@ -36,10 +36,17 @@
 static bool state;
 static bool pid;
 static char *test_state = NULL;
+static char **key = NULL;
+static int keys = 0;
 
 static int my_parser(struct lxc_arguments* args, int c, char* arg)
 {
 	switch (c) {
+	case 'c':
+		key = realloc(key, keys+1 * sizeof(key[0]));
+		key[keys] = arg;
+		keys++;
+		break;
 	case 's': state = true; break;
 	case 'p': pid = true; break;
 	case 't': test_state = arg; break;
@@ -48,6 +55,7 @@ static int my_parser(struct lxc_arguments* args, int c, char* arg)
 }
 
 static const struct option my_longopts[] = {
+	{"config", required_argument, 0, 'c'},
 	{"state", no_argument, 0, 's'},
 	{"pid", no_argument, 0, 'p'},
 	{"state-is", required_argument, 0, 't'},
@@ -63,8 +71,9 @@ lxc-info display some information about a container with the identifier NAME\n\
 \n\
 Options :\n\
   -n, --name=NAME       NAME for name of the container\n\
-  -s, --state           shows the state of the container\n\
+  -c, --config=KEY      show configuration variable KEY from running container\n\
   -p, --pid             shows the process id of the init container\n\
+  -s, --state           shows the state of the container\n\
   -t, --state-is=STATE  test if current state is STATE\n\
                         returns success if it matches, false otherwise\n",
 	.options  = my_longopts,
@@ -74,7 +83,7 @@ Options :\n\
 
 int main(int argc, char *argv[])
 {
-	int ret;
+	int ret,i;
 
 	ret = lxc_arguments_parse(&my_args, argc, argv);
 	if (ret)
@@ -84,7 +93,7 @@ int main(int argc, char *argv[])
 			 my_args.progname, my_args.quiet, my_args.lxcpath[0]))
 		return 1;
 
-	if (!state && !pid)
+	if (!state && !pid && keys <= 0)
 		state = pid = true;
 
 	if (state || test_state) {
@@ -105,5 +114,17 @@ int main(int argc, char *argv[])
 			printf("pid:%10d\n", initpid);
 	}
 
+	for(i = 0; i < keys; i++) {
+		char *val;
+
+		val = lxc_cmd_get_config_item(my_args.name, key[i], my_args.lxcpath[0]);
+		if (val) {
+			printf("%s = %s\n", key[i], val);
+			free(val);
+		} else {
+			fprintf(stderr, "%s unset or invalid\n", key[i]);
+		}
+	}
+
 	return 0;
 }