Make all plugins dynamically loaded.

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

config/example.conf

@@ -3,6 +3,7 @@ fence_virtd {
 	listener = "multicast";
 	backend = "libvirt";
 	name_mode = "name";
+	module_path = "/usr/lib64/fence_virt";
 }
 
 listeners {

include/server_plugin.h

@@ -103,6 +103,7 @@ const listener_plugin_t *plugin_find_listener(const char *name);
 
 void plugin_dump(void);
 #ifdef _MODULE
-int plugin_load(const char *libpath);
+int plugin_load(const char *filename);
+int plugin_search(const char *pathname);
 #endif
 

server/Makefile

@@ -15,12 +15,14 @@ include ../Makefile.top
 
 TARGETS=fence_virtd
 
-MODULES=libvirt.so checkpoint.so
+MODULES=libvirt.so checkpoint.so multicast.so
 
-fence_virtd_SOURCES = mcast.c main.c plugin.c
+fence_virtd_SOURCES = main.c plugin.c
 
 libvirt_so_SOURCES = libvirt.c
 
+multicast_so_SOURCES = mcast.c
+
 checkpoint_so_SOURCES = virt.c vm_states.c
 
 INCLUDES=-I../include\
@@ -41,6 +43,9 @@ all: ${TARGETS} ${MODULES}
 fence_virtd: ${fence_virtd_SOURCES:.c=.o}
 	gcc -o $@ $^ $(LIBS) $(MAIN_LIBS)
 
+multicast.so: ${multicast_so_SOURCES:.c=.o}
+	gcc -o $@ $^ $(LIBS) -shared
+
 libvirt.so: ${libvirt_so_SOURCES:.c=.o}
 	gcc -o $@ $^ $(LIBS) -shared
 

server/main.c

@@ -15,7 +15,7 @@
 int
 main(int argc, char **argv)
 {
-	char val[80];
+	char val[4096];
 	char listener_name[80];
 	char backend_name[80];
 	const char *config_file = DEFAULT_CONFIG_FILE;
@@ -74,14 +74,24 @@ main(int argc, char **argv)
 	printf("Backend plugin: %s\n", backend_name);
 
 #ifdef _MODULE
-	if (plugin_load("./libvirt.so") < 0) {
-		printf("Doom\n");
+	if (sc_get(config, "fence_virtd/@module_path", val,
+		   sizeof(val))) {
+		printf("Failed to determine module path.\n");
+		return -1;
 	}
-	if (plugin_load("/usr/lib64/fence_virt/libvirt.so") < 0) {
-		printf("Doom\n");
+
+	printf("Searching %s for plugins...\n", val);
+
+	opt = plugin_search(val);
+	if (opt > 0) {
+		printf("%d plugins found\n", opt);
+	} else {
+		printf("No plugins found\n");
+		return 1;
 	}
-#endif
+
 	plugin_dump();
+#endif
 
 	lp = plugin_find_listener(listener_name);
 	if (!lp) {

server/mcast.c

@@ -552,7 +552,7 @@ static listener_plugin_t mcast_plugin = {
 };
 
 
-#ifdef _MODULE_FOO
+#ifdef _MODULE
 double
 LISTENER_VER_SYM(void)
 {

server/plugin.c

@@ -25,7 +25,6 @@
 #include <stdio.h>
 #include <sys/types.h>
 #include <sys/stat.h>
-#include <dirent.h>
 #include <unistd.h>
 
 #include <list.h>
@@ -33,7 +32,7 @@
 #include <server_plugin.h>
 #include <malloc.h>
 #include <string.h>
-
+#include <dirent.h>
 
 typedef struct _plugin_list {
 	list_head();
@@ -44,11 +43,17 @@ typedef struct _plugin_list {
 
 static plugin_list_t *server_plugins = NULL;
 
+
 int
 plugin_reg_backend(const backend_plugin_t *plugin)
 {
 	plugin_list_t *newplug;
 
+	if (plugin_find_backend(plugin->name)) {
+		errno = EEXIST;
+		return -1;
+	}
+
 	newplug = malloc(sizeof(*newplug));
 	if (!newplug) 
 		return -1;
@@ -66,6 +71,11 @@ plugin_reg_listener(const listener_plugin_t *plugin)
 {
 	plugin_list_t *newplug;
 
+	if (plugin_find_listener(plugin->name)) {
+		errno = EEXIST;
+		return -1;
+	}
+
 	newplug = malloc(sizeof(*newplug));
 	if (!newplug) 
 		return -1;
@@ -95,6 +105,7 @@ plugin_dump(void)
 	}
 }
 
+
 const backend_plugin_t *
 plugin_find_backend(const char *name)
 {
@@ -129,6 +140,109 @@ plugin_find_listener(const char *name)
 }
 
 
+static int
+backend_plugin_load(void *handle, const char *libpath)
+{
+	const backend_plugin_t *plug = NULL;
+	double (*modversion)(void);
+	backend_plugin_t *(*modinfo)(void);
+
+	modversion = dlsym(handle, BACKEND_VER_STR);
+	if (!modversion) {
+#ifdef DEBUG
+		printf("Failed to map %s\n", BACKEND_VER_STR);
+#endif
+		errno = EINVAL;
+		return -1;
+	}
+
+	if (modversion() != PLUGIN_VERSION_BACKEND) {
+#ifdef DEBUG
+		printf("API version mismatch in %s: \n"
+		       "       %f expected; %f received.\n", libpath,
+		       PLUGIN_VERSION_BACKEND, modversion());
+#endif
+		errno = EINVAL;
+		return -1;
+	}
+
+	modinfo = dlsym(handle, BACKEND_INFO_STR);
+	if (!modinfo) {
+#ifdef DEBUG
+		printf("Failed to map %s\n", BACKEND_INFO_STR);
+#endif
+		errno = EINVAL;
+		return -1;
+	}
+
+	plug = modinfo();
+	if (plugin_reg_backend(plug) < 0) {
+		errno = EINVAL;
+		return -1;
+	}
+#ifdef DEBUG
+       	else {
+		printf("Registered backend plugin %s %s\n",
+		       plug->name, plug->version);
+	}
+#endif
+
+	return 0;
+}
+
+
+static int
+listener_plugin_load(void *handle, const char *libpath)
+{
+	const listener_plugin_t *plug = NULL;
+	double (*modversion)(void);
+	listener_plugin_t *(*modinfo)(void);
+
+	modversion = dlsym(handle, LISTENER_VER_STR);
+	if (!modversion) {
+#ifdef DEBUG
+		printf("Failed to map %s\n", LISTENER_VER_STR);
+#endif
+		errno = EINVAL;
+		return -1;
+	}
+
+	if (modversion() != PLUGIN_VERSION_LISTENER) {
+#ifdef DEBUG
+		printf("API version mismatch in %s: \n"
+		       "       %f expected; %f received.\n", libpath,
+		       PLUGIN_VERSION_LISTENER, modversion());
+#endif
+		dlclose(handle);
+		errno = EINVAL;
+		return -1;
+	}
+
+	modinfo = dlsym(handle, LISTENER_INFO_STR);
+	if (!modinfo) {
+#ifdef DEBUG
+		printf("Failed to map %s\n", LISTENER_INFO_STR);
+#endif
+		errno = EINVAL;
+		return -1;
+	}
+
+	plug = modinfo();
+	if (plugin_reg_listener(plug) < 0) {
+		errno = EINVAL;
+		return -1;
+	}
+#ifdef DEBUG
+       	else {
+		printf("Registered listener plugin %s %s\n",
+		       plug->name, plug->version);
+	}
+#endif
+
+	return 0;
+}
+
+
 /**
  * Load a cluster plugin .so file and map all the functions
  * provided to entries in a backend_plugin_t structure.
@@ -142,9 +256,6 @@ int
 plugin_load(const char *libpath)
 {
 	void *handle = NULL;
-	const backend_plugin_t *plug = NULL;
-	double (*modversion)(void);
-	backend_plugin_t *(*modinfo)(void);
 	struct stat sb;
 
 	errno = 0;
@@ -178,52 +289,140 @@ plugin_load(const char *libpath)
 		return -1;
 	}
 
+#ifdef DEBUG
+	printf("Loading plugin from %s\n", libpath);
+#endif
 	handle = dlopen(libpath, RTLD_LAZY);
 	if (!handle) {
 		errno = ELIBACC;
 		return -1;
 	}
 
-	modversion = dlsym(handle, BACKEND_VER_STR);
-	if (!modversion) {
-#ifdef DEBUG
-		printf("Failed to map %s\n", BACKEND_VER_STR);
-#endif
+	if (!backend_plugin_load(handle, libpath) ||
+	    !listener_plugin_load(handle, libpath))
+		return 0;
+
 	dlclose(handle);
 	errno = EINVAL;
 	return -1;
+}
+
+/**
+  Free up a null-terminated array of strings
+ */
+static void
+free_dirnames(char **dirnames)
+{
+	int x = 0;
+
+	for (; dirnames[x]; x++)
+		free(dirnames[x]);
+
+	free(dirnames);
+}
+
+
+static int
+_compare(const void *a, const void *b)
+{
+	return strcmp((const char *)a, (const char *)b);
+}
+
+
+/**
+  Read all entries in a directory and return them in a NULL-terminated,
+  sorted array.
+ */
+static int
+read_dirnames_sorted(const char *directory, char ***dirnames)
+{
+	DIR *dir;
+	struct dirent *entry;
+	char filename[1024];
+	int count = 0, x = 0;
+
+	dir = opendir(directory);
+	if (!dir)
+		return -1;
+
+	/* Count the number of plugins */
+	while ((entry = readdir(dir)) != NULL)
+		++count;
+
+	/* Malloc the entries */
+	*dirnames = malloc(sizeof(char *) * (count+1));
+	if (!*dirnames) {
+#ifdef DEBUG
+		printf("%s: Failed to malloc %d bytes",
+		       __FUNCTION__, (int)(sizeof(char *) * (count+1)));
+#endif
+		closedir(dir);
+		errno = ENOMEM;
+		return -1;
+	}
+	memset(*dirnames, 0, sizeof(char *) * (count + 1));
+	rewinddir(dir);
+
+	/* Store the directory names. */
+	while ((entry = readdir(dir)) != NULL) {
+		snprintf(filename, sizeof(filename), "%s/%s", directory,
+			 entry->d_name);
+
+		(*dirnames)[x] = strdup(filename);
+		if (!(*dirnames)[x]) {
+#ifdef DEBUG
+			printf("Failed to duplicate %s\n",
+			       filename);
+#endif
+			free_dirnames(*dirnames);
+			closedir(dir);
+			errno = ENOMEM;
+			return -1;
+		}
+		++x;
 	}
 
-	if (modversion() != PLUGIN_VERSION_BACKEND) {
-#ifdef DEBUG
-		printf("API version mismatch in %s: \n"
-		       "       %f expected; %f received.\n", libpath,
-			, modversion());
-#endif
-		dlclose(handle);
-		errno = EINVAL;
-		return -1;
-	}
+	closedir(dir);
 
-	modinfo = dlsym(handle, BACKEND_INFO_STR);
-	if (!modinfo) {
-#ifdef DEBUG
-		printf("Failed to map %s\n", BACKEND_INFO_STR);
-#endif
-		dlclose(handle);
-		errno = EINVAL;
-		return -1;
-	}
-
-	plug = modinfo();
-	if (plugin_reg_backend(plug) < 0) {
-		dlclose(handle);
-		errno = EINVAL;
-		return -1;
-	} else {
-		printf("Registered plugin %s %s\n",
-		       plug->name, plug->version);
-	}
+	/* Sort the directory names. */
+	qsort((*dirnames), count, sizeof(char *), _compare);
 
 	return 0;
 }
+
+
+/**
+ */
+int
+plugin_search(const char *pathname)
+{
+	int found = 0;
+	int fcount = 0;
+	char **filenames;
+
+#ifdef DEBUG
+	printf("Trying plugins in %s\n", pathname);
+#endif
+	if (read_dirnames_sorted(pathname, &filenames) != 0) {
+		return -1;
+	}
+
+	for (fcount = 0; filenames[fcount]; fcount++) {
+
+		if (plugin_load(filenames[fcount]) == 0)
+			++found;
+	}
+
+	free_dirnames(filenames);
+	if (!found) {
+#ifdef DEBUG
+		printf("No usable plugins found.\n");
+#endif
+		errno = ELIBACC;
+		return -1;
+	}
+
+	return found;
+}
+
+