Make libvirt a built-in plugin

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

include/list.h

@@ -0,0 +1,94 @@
+#ifndef _LIST_H
+#define _LIST_H
+
+/**
+  Simple list handlig macros.
+  Needs rewrite or inclusion of /usr/include/linux/list.h as a replacement.
+ */
+
+/* Must be first if structure is going to use it. */
+struct list_entry {
+	struct list_entry *le_next, *le_prev;
+};
+
+#define list_head() struct list_entry _list_head
+
+#define le(p) (&((*p)._list_head))
+
+#define list_insert(list, newnode) \
+do { \
+	if (!(*list)) { \
+		le(newnode)->le_next = \
+		le(newnode)->le_prev = le(newnode); \
+		*list = (void *)le(newnode); \
+	} else { \
+		le(*list)->le_prev->le_next = le(newnode); \
+		le(newnode)->le_next = le(*list); \
+		le(newnode)->le_prev = le(*list)->le_prev; \
+		le(*list)->le_prev = le(newnode); \
+	} \
+} while (0)
+
+	
+#define list_prepend(list, newnode) \
+do { \
+	list_insert(list, newnode); \
+	*list = newnode; \
+} while (0)
+
+
+#define list_remove(list, oldnode) \
+do { \
+	if (le(oldnode) == le(*list)) { \
+		*list = (void *)le(*list)->le_next; \
+	} \
+	if (le(oldnode) == le(*list)) { \
+		le(oldnode)->le_next = NULL; \
+		le(oldnode)->le_prev = NULL; \
+		*list = NULL; \
+	} else { \
+		le(oldnode)->le_next->le_prev = le(oldnode)->le_prev; \
+		le(oldnode)->le_prev->le_next = le(oldnode)->le_next; \
+		le(oldnode)->le_prev = NULL; \
+	       	le(oldnode)->le_next = NULL; \
+	} \
+} while (0)
+
+/*
+   list_do(list, node) {
+   	stuff;
+   } while (!list_done(list, node));
+ */
+#define list_do(list, curr) \
+	if (*list && (curr = *list)) do
+
+#define list_done(list, curr) \
+	(curr && (((curr = (void *)le(curr)->le_next)) && (curr == *list)))
+
+/*
+ * list_for(list, tmp, counter) {
+ *     stuff;
+ * }
+ * 
+ * counter = # of items in list when done.
+ * * sets cnt to 0 before even checking list;
+ * * checks for valid list
+ * * traverses list, incrementing counter.  If we get to the for loop,
+ *   there must be at least one item in the list
+ * * cnt ends up being the number of items in the list.
+ */
+#define list_for(list, curr, cnt) \
+	if (!(cnt=0) && (list != NULL) && (*list != NULL)) \
+		for (curr = *list; \
+		     (cnt == 0) || (curr != *list); \
+		     curr = (void*)le(curr)->le_next, \
+		     cnt++)
+			
+#define list_for_rev(list, curr, cnt) \
+	if (!(cnt=0) && list && *list) \
+		for (curr = (void *)(le(*list)->le_prev); \
+		     (cnt == 0) || ((void *)curr != le(*list)->le_prev); \
+		     curr = (void*)(le(curr)->le_prev), \
+		     cnt++)
+
+#endif

include/server_plugin.h

@@ -36,6 +36,9 @@ typedef int (*fence_status_callback)(const char *vm_name,
    is responding to requests. */
 typedef int (*fence_devstatus_callback)(void *priv);
 
+typedef int (*fence_init_callback)(srv_context_t *c);
+typedef int (*fence_cleanup_callback)(srv_context_t c);
+
 typedef struct _fence_callbacks {
 	fence_null_callback null;
 	fence_off_callback off;
@@ -45,10 +48,19 @@ typedef struct _fence_callbacks {
 	fence_devstatus_callback devstatus;
 } fence_callbacks_t;
 
+typedef struct _backend_plugin {
+	const char *name;
+	const char *version;
+	const fence_callbacks_t *callbacks;
+	fence_init_callback init;
+	fence_cleanup_callback cleanup;
+} plugin_t;
 
-extern fence_callbacks_t libvirt_callbacks;
-int libvirt_init(srv_context_t *c);
-int libvirt_shutdown(srv_context_t c);
+#ifndef _USE_MODULES
+void plugin_register(const plugin_t *plugin);
+const plugin_t *plugin_find(const char *name);
+void plugin_dump(void);
+#endif
 
 
 /* TODO: make these 'plugins' instead of static uses */
@@ -73,7 +85,7 @@ typedef struct {
 	unsigned int auth;
 } mcast_options;
 
-int mcast_init(srv_context_t *, fence_callbacks_t *,
+int mcast_init(srv_context_t *, const fence_callbacks_t *,
 	       mcast_options *, void *priv);
 int mcast_dispatch(srv_context_t, struct timeval *timeout);
 int mcast_shutdown(srv_context_t);

server/Makefile

@@ -13,7 +13,7 @@
 
 TARGETS=fence_virtd
 
-fence_virtd_SOURCES = mcast.c libvirt.c main.c
+fence_virtd_SOURCES = mcast.c libvirt.c main.c plugin.c
 
 INCLUDES=-I../include\
 	-I/usr/include/openais -I/usr/include/libvirt \

server/libvirt.c

@@ -57,6 +57,9 @@
 #include "debug.h"
 
 
+#define NAME "libvirt"
+#define VERSION "0.1"
+
 static inline int
 wait_domain(const char *vm_name, virConnectPtr vp, int timeout)
 {
@@ -273,7 +276,7 @@ libvirt_reboot(const char *vm_name, void *priv)
 	return ret;
 }
 
-int
+static int
 libvirt_init(srv_context_t *c)
 {
 	virConnectPtr vp;
@@ -286,14 +289,14 @@ libvirt_init(srv_context_t *c)
 }
 
 
-int
+static int
 libvirt_shutdown(srv_context_t c)
 {
 	return virConnectClose((virConnectPtr)c);
 }
 
 
-fence_callbacks_t libvirt_callbacks = {
+static fence_callbacks_t libvirt_callbacks = {
 	.null = libvirt_null,
 	.off = libvirt_off,
 	.on = libvirt_on,
@@ -301,3 +304,26 @@ fence_callbacks_t libvirt_callbacks = {
 	.status = libvirt_status,
 	.devstatus = libvirt_devstatus
 };
+
+#ifdef _MODULE
+fence_callbacks_t *
+plugin_callbacks(void)
+{
+	return &libvirt_callbacks;
+}
+#else
+
+static plugin_t libvirt_plugin = {
+	.name = NAME,
+	.version = VERSION,
+	.callbacks = &libvirt_callbacks,
+	.init = libvirt_init,
+	.cleanup = libvirt_shutdown,
+};
+
+static void __attribute__((constructor))
+initialize_plugin(void)
+{
+	plugin_register(&libvirt_plugin);
+}
+#endif

server/main.c

@@ -14,21 +14,28 @@ extern fence_callbacks_t libvirt_callbacks; /* should be in a header */
 int
 main(int argc, char **argv)
 {
+	const char *plugin_name = "libvirt";
+	const plugin_t *p;
 	srv_context_t mcast_context;
 	srv_context_t libvirt_context; /*XXX these should be differently
 					 named context types */
 
 	dset(99);
 
-	/* Only backend we have right now is basic libvirt */
+	plugin_dump();
 
-	if (libvirt_init(&libvirt_context) < 0) {
-		printf("Libvirt failed to initialize\n");
+	p = plugin_find(plugin_name);
+	if (!p) {
+		printf("Could not find plugin \"%s\n", plugin_name);
+	}
+
+	if (p->init(&libvirt_context) < 0) {
+		printf("%s failed to initialize\n", plugin_name);
 		return 1;
 	}
 
 	/* only client we have now is mcast (fence_xvm behavior) */
-	if (mcast_init(&mcast_context, &libvirt_callbacks, NULL,
+	if (mcast_init(&mcast_context, p->callbacks, NULL,
 		       libvirt_context) < 0) {
 		printf("Failed initialization!\n");
 		return 1;
@@ -37,7 +44,7 @@ main(int argc, char **argv)
 	while (mcast_dispatch(mcast_context, NULL) >= 0);
 
 	mcast_shutdown(mcast_context);
-	libvirt_shutdown(libvirt_context);
+	p->cleanup(libvirt_context);
 
 	return 0;
 }

server/mcast.c

@@ -65,7 +65,7 @@ typedef struct _mcast_info {
 	void *priv;
 	char key[MAX_KEY_LEN];
 	mcast_options *args;
-	fence_callbacks_t *cb;
+	const fence_callbacks_t *cb;
 	ssize_t key_len;
 	int mc_sock;
 	int need_kill;
@@ -280,7 +280,7 @@ mcast_dispatch(srv_context_t c, struct timeval *timeout)
 
 
 int
-mcast_init(srv_context_t *c, fence_callbacks_t *cb,
+mcast_init(srv_context_t *c, const fence_callbacks_t *cb,
 	   mcast_options *args, void *priv)
 {
 	mcast_info *info;

server/plugin.c

@@ -0,0 +1,67 @@
+#include <stdio.h>
+#include <list.h>
+#include <server_plugin.h>
+#include <malloc.h>
+#include <string.h>
+
+
+typedef struct _plugin_list {
+	list_head();
+	const plugin_t *plugin;
+} plugin_list_t;
+
+static plugin_list_t *server_plugins = NULL;
+
+void
+plugin_register(const plugin_t *plugin)
+{
+	plugin_list_t *newplug;
+
+	newplug = malloc(sizeof(*newplug));
+	if (!newplug)
+		return;
+	memset(newplug, 0, sizeof(*newplug));
+	newplug->plugin = plugin;
+	list_insert(&server_plugins, newplug);
+}
+
+void
+plugin_dump(void)
+{
+	plugin_list_t *p;
+	int x;
+
+	list_for(&server_plugins, p, x) {
+		printf("%s %s\n", p->plugin->name, p->plugin->version);
+	}
+}
+
+const plugin_t *
+plugin_find(const char *name)
+{
+	plugin_list_t *p;
+	int x;
+
+	list_for(&server_plugins, p, x) {
+		if (!strcasecmp(name, p->plugin->name))
+			return p->plugin;
+	}
+
+	return NULL;
+}
+
+
+int
+plugin_init(const plugin_t *p, srv_context_t *c)
+{
+	return p->init(c);
+}
+
+
+int
+plugin_shutdown(const plugin_t *p, srv_context_t c)
+{
+	return p->cleanup(c);
+}
+
+