Add simple 'null' skeleton backend plugin

Signed-off-by: Lon Hohberger <lhh@redhat.com>

server/Makefile

@@ -15,14 +15,12 @@ include ../Makefile.top
 
 TARGETS=fence_virtd
 
-MODULES=libvirt.so checkpoint.so multicast.so
+MODULES=libvirt.so checkpoint.so multicast.so null.so
 
 fence_virtd_SOURCES = main.c plugin.c
-
 libvirt_so_SOURCES = libvirt.c
-
+null_so_SOURCES = null.c
 multicast_so_SOURCES = mcast.c
-
 checkpoint_so_SOURCES = virt.c vm_states.c
 
 INCLUDES=-I../include\
@@ -49,6 +47,9 @@ multicast.so: ${multicast_so_SOURCES:.c=.o}
 libvirt.so: ${libvirt_so_SOURCES:.c=.o}
 	gcc -o $@ $^ $(LIBS) -shared
 
+null.so: ${null_so_SOURCES:.c=.o}
+	gcc -o $@ $^ $(LIBS) -shared
+
 checkpoint.so: ${checkpoint_so_SOURCES:.c=.o}
 	gcc -o $@ $^ $(LIBS) -shared
 

server/null.c

@@ -0,0 +1,197 @@
+/*
+  Copyright Red Hat, Inc. 2009
+
+  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, 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; see the file COPYING.  If not, write to the
+  Free Software Foundation, Inc.,  675 Mass Ave, Cambridge, 
+  MA 02139, USA.
+*/
+/*
+ * Author: Lon Hohberger <lhh at redhat.com>
+ */
+#include <stdio.h>
+#include <simpleconfig.h>
+#include <server_plugin.h>
+#include <string.h>
+#include <malloc.h>
+#include <errno.h>
+
+/* Local includes */
+#include "debug.h"
+
+
+#define NAME "null"
+#define VERSION "0.8"
+
+#define MAGIC 0x1e00017a
+
+struct null_info {
+	int magic;
+	int pad;
+	char *message;
+};
+
+#define VALIDATE(arg) \
+do {\
+	if (!arg || ((struct null_info *)arg)->magic != MAGIC) { \
+		errno = EINVAL;\
+		return -1; \
+	} \
+} while(0)
+
+
+static int
+null_null(const char *vm_name, void *priv)
+{
+	VALIDATE(priv);
+	printf("[Null] Null operation on %s\n", vm_name);
+
+	return 1;
+}
+
+
+static int
+null_off(const char *vm_name, void *priv)
+{
+	VALIDATE(priv);
+	printf("[Null] OFF operation on %s\n", vm_name);
+
+	return 1;
+}
+
+
+static int
+null_on(const char *vm_name, void *priv)
+{
+	VALIDATE(priv);
+	printf("[Null] ON operation on %s\n", vm_name);
+
+	return 1;
+}
+
+
+static int
+null_devstatus(void *priv)
+{
+	printf("[Null] Device status\n");
+	VALIDATE(priv);
+	printf("[Null] Message for you: %s\n",
+	       ((struct null_info *)priv)->message);
+
+	return 0;
+}
+
+
+static int
+null_status(const char *vm_name, void *priv)
+{
+	VALIDATE(priv);
+	printf("[Null] STATUS operation on %s\n", vm_name);
+
+	return 1;
+}
+
+
+static int
+null_reboot(const char *vm_name, void *priv)
+{
+	VALIDATE(priv);
+	printf("[Null] REBOOT operation on %s\n", vm_name);
+
+	return 1;
+}
+
+
+static int
+null_init(backend_context_t *c, config_object_t *config)
+{
+	char value[256];
+	struct null_info *info = NULL;
+	char *null_message = NULL;
+
+	info = malloc(sizeof(*info));
+	if (!info)
+		return -1;
+
+	memset(info, 0, sizeof(*info));
+
+	if (sc_get(config, "backends/null/@message",
+		   value, sizeof(value)) != 0) {
+		snprintf(value, sizeof(value), "Hi!");
+	}
+
+	null_message = strdup(value);
+	if (!null_message) {
+		free(info);
+		return -1;
+	}
+
+	info->magic = MAGIC;
+	info->message = null_message;
+
+	*c = (void *)info;
+	return 0;
+}
+
+
+static int
+null_shutdown(backend_context_t c)
+{
+	struct null_info *info = (struct null_info *)c;
+
+	VALIDATE(info);
+	info->magic = 0;
+	free(info->message);
+	free(info);
+
+	return 0;
+}
+
+
+static fence_callbacks_t null_callbacks = {
+	.null = null_null,
+	.off = null_off,
+	.on = null_on,
+	.reboot = null_reboot,
+	.status = null_status,
+	.devstatus = null_devstatus
+};
+
+static backend_plugin_t null_plugin = {
+	.name = NAME,
+	.version = VERSION,
+	.callbacks = &null_callbacks,
+	.init = null_init,
+	.cleanup = null_shutdown,
+};
+
+
+#ifdef _MODULE
+double
+BACKEND_VER_SYM(void)
+{
+	return PLUGIN_VERSION_BACKEND;
+}
+
+const backend_plugin_t *
+BACKEND_INFO_SYM(void)
+{
+	return &null_plugin;
+}
+#else
+static void __attribute__((constructor))
+null_register_plugin(void)
+{
+	plugin_register(&null_plugin);
+}
+#endif