Create server-side plugin architecture

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

Makefile.top

@@ -0,0 +1 @@
+CFLAGS=-fPIC -Wall -Wstrict-prototypes -Werror -ggdb -D_GNU_SOURCE

client/Makefile

@@ -10,6 +10,7 @@
 ###############################################################################
 ###############################################################################
 
+include=../Makefile.top
 
 TARGETS=fence_virt fence_xvm
 
@@ -21,8 +22,7 @@ INCLUDES=-I../include\
 	-I../../../cman/lib -I../../../ccs/lib -I/usr/include/libxml2 \
 	-I/usr/include/libvirt
 
-CFLAGS+=-DFENCE_RELEASE_NAME=\"devel\" \
+CFLAGS+=-DFENCE_RELEASE_NAME=\"devel\"
-	-Wall -Werror -Wstrict-prototypes -Wshadow -ggdb -D_GNU_SOURCE
 
 LIBS+=-L../../../cman/lib -L../../../ccs/lib -L${libdir}/openais \
       -L../../../dlm/lib -lnss3 -lxml2

common/Makefile

@@ -10,6 +10,7 @@
 ###############################################################################
 ###############################################################################
 
+include ../Makefile.top
 
 TARGETS=libfence_virt.a
 
@@ -22,8 +23,7 @@ INCLUDES=-I../include \
 	-I../../../cman/lib -I../../../ccs/lib -I/usr/include/libxml2 \
 	-I/usr/include/libvirt
 
-CFLAGS+=-DFENCE_RELEASE_NAME=\"devel\" \
+CFLAGS+=-DFENCE_RELEASE_NAME=\"devel\"
-	-Wall -Werror -Wstrict-prototypes -Wshadow -ggdb -D_GNU_SOURCE
 
 LIBS+=-L../../../cman/lib -L../../../ccs/lib -L${libdir}/openais \
       -L../../../dlm/lib -lnss3 -lxml2

include/options.h

@@ -33,7 +33,7 @@ typedef enum {
 
 typedef enum {
 	MODE_MULTICAST  = 0,
-	//MODE_BROADCAST  = 1,
+	/*MODE_BROADCAST  = 1,*/
 	MODE_SERIAL     = 2,
 	MODE_VMCHANNEL  = 3
 } client_mode_t;

include/server_plugin.h

@@ -1,8 +1,21 @@
-
 /*  */
-
 #include <uuid/uuid.h>
 
+#define PLUGIN_VERSION_FRONTEND ((double)0.1)
+#define PLUGIN_VERSION_BACKEND  ((double)0.1)
+
+#define FRONTEND_VER_SYM frontend_plugin_version
+#define BACKEND_VER_SYM backend_plugin_version
+#define FRONTEND_INFO_SYM frontend_plugin_info
+#define BACKEND_INFO_SYM backend_plugin_info
+#define FRONTEND_VER_STR "frontend_plugin_version"
+#define BACKEND_VER_STR "backend_plugin_version"
+#define FRONTEND_INFO_STR "frontend_plugin_info"
+#define BACKEND_INFO_STR "backend_plugin_info"
+
+
+
+
 typedef void * srv_context_t;
 
 /* These callbacks hand requests off to the
@@ -56,10 +69,11 @@ typedef struct _backend_plugin {
 	fence_cleanup_callback cleanup;
 } plugin_t;
 
-#ifndef _USE_MODULES
+int plugin_register(const plugin_t *plugin);
-void plugin_register(const plugin_t *plugin);
 const plugin_t *plugin_find(const char *name);
 void plugin_dump(void);
+#ifdef _MODULE
+int plugin_load(const char *libpath);
 #endif
 
 

include/xvm.h

@@ -43,7 +43,7 @@ typedef enum {
 	AUTH_NONE = 0x0,	/* Plain TCP */
 	AUTH_SHA1 = 0x1,	/* Challenge-response (SHA1) */
   	AUTH_SHA256 = 0x2,      /* Challenge-response (SHA256) */
-	AUTH_SHA512 = 0x3,      /* Challenge-response (SHA512) */
+	AUTH_SHA512 = 0x3       /* Challenge-response (SHA512) */
      /* AUTH_SSL_X509 = 0x10        SSL X509 certificates */
 } fence_auth_type_t;
 

server/Makefile

@@ -10,10 +10,14 @@
 ###############################################################################
 ###############################################################################
 
+include ../Makefile.top
 
-TARGETS=fence_virtd
 
-fence_virtd_SOURCES = mcast.c libvirt.c main.c plugin.c
+TARGETS=fence_virtd libvirt.so
+
+fence_virtd_SOURCES = mcast.c main.c plugin.c
+
+libvirt_so_SOURCES = libvirt.c
 
 INCLUDES=-I../include\
 	-I/usr/include/openais -I/usr/include/libvirt \
@@ -21,8 +25,7 @@ INCLUDES=-I../include\
 	-I../../../cman/lib -I../../../ccs/lib -I/usr/include/libxml2 \
 	-I/usr/include/libvirt
 
-CFLAGS+=-DFENCE_RELEASE_NAME=\"devel\" \
+CFLAGS+=-DFENCE_RELEASE_NAME=\"devel\" -D_MODULE
-	-Wall -Werror -Wstrict-prototypes -Wshadow -ggdb -D_GNU_SOURCE
 
 LIBS+=-L/usr/lib64/openais -lnss3 -lxml2 -lSaCkpt -lccs -lvirt -lcman \
       -L../common -lfence_virt
@@ -32,6 +35,9 @@ all: ${TARGETS}
 fence_virtd: ${fence_virtd_SOURCES:.c=.o}
 	gcc -o $@ $^ $(LIBS) -L../common -lfence_virt
 
+libvirt.so: ${libvirt_so_SOURCES:.c=.o}
+	gcc -o $@ $^ $(LIBS) -shared -L../common -lvirt
+
 %.o: %.c
 	gcc $(CFLAGS) -c -o $@ $^ $(INCLUDES)
 

server/libvirt.c

@@ -305,14 +305,6 @@ static fence_callbacks_t libvirt_callbacks = {
 	.devstatus = libvirt_devstatus
 };
 
-#ifdef _MODULE
-fence_callbacks_t *
-plugin_callbacks(void)
-{
-	return &libvirt_callbacks;
-}
-#else
-
 static plugin_t libvirt_plugin = {
 	.name = NAME,
 	.version = VERSION,
@@ -321,8 +313,22 @@ static plugin_t libvirt_plugin = {
 	.cleanup = libvirt_shutdown,
 };
 
+
+#ifdef _MODULE
+double
+BACKEND_VER_SYM(void)
+{
+	return PLUGIN_VERSION_BACKEND;
+}
+
+const plugin_t *
+BACKEND_INFO_SYM(void)
+{
+	return &libvirt_plugin;
+}
+#else
 static void __attribute__((constructor))
-initialize_plugin(void)
+libvirt_register_plugin(void)
 {
 	plugin_register(&libvirt_plugin);
 }

server/main.c

@@ -22,6 +22,11 @@ main(int argc, char **argv)
 
 	dset(99);
 
+#ifdef _MODULE
+	if (plugin_load("./libvirt.so") < 0) {
+		printf("Doom\n");
+	}
+#endif
 	plugin_dump();
 
 	p = plugin_find(plugin_name);

server/plugin.c

@@ -1,4 +1,33 @@
+/*
+  Copyright Red Hat, Inc. 2002-2004, 2009
+
+  The Magma Cluster API Library is free software; you can redistribute
+  it and/or modify it under the terms of the GNU Lesser General Public
+  License as published by the Free Software Foundation; either version
+  2.1 of the License, or (at your option) any later version.
+
+  The Magma Cluster API Library 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
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public
+  License along with this library; if not, write to the Free Software
+  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
+  USA.
+ */
+/** @file
+ * Plugin loading routines
+ */
+#include <dlfcn.h>
+#include <stdlib.h>
+#include <errno.h>
 #include <stdio.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <dirent.h>
+#include <unistd.h>
+
 #include <list.h>
 #include <server_plugin.h>
 #include <malloc.h>
@@ -12,17 +41,18 @@ typedef struct _plugin_list {
 
 static plugin_list_t *server_plugins = NULL;
 
-void
+int
 plugin_register(const plugin_t *plugin)
 {
 	plugin_list_t *newplug;
 
 	newplug = malloc(sizeof(*newplug));
 	if (!newplug) 
-		return;
+		return -1;
 	memset(newplug, 0, sizeof(*newplug));
 	newplug->plugin = plugin;
 	list_insert(&server_plugins, newplug);
+	return 0;
 }
 
 void
@@ -64,4 +94,101 @@ plugin_shutdown(const plugin_t *p, srv_context_t c)
 	return p->cleanup(c);
 }
 
+/**
+ * Load a cluster plugin .so file and map all the functions
+ * provided to entries in a plugin_t structure.
+ *
+ * @param libpath	Path to file.
+ * @return		NULL on failure, or plugin-specific
+ * 			(const) plugin_t * structure on
+ * 			success.
+ */
+int
+plugin_load(const char *libpath)
+{
+	void *handle = NULL;
+	const plugin_t *plug = NULL;
+	double (*modversion)(void);
+	plugin_t *(*modinfo)(void);
+	struct stat sb;
 
+	errno = 0;
+
+	if (!libpath) {
+		errno = EINVAL;
+		return -1;
+	}
+
+	if (stat(libpath, &sb) != 0) {
+		return -1;
+	}
+
+	/*
+	   If it's not owner-readable or it's a directory,
+	   ignore/fail.  Thus, a user may change the permission of
+	   a plugin "u-r" and this would then prevent magma apps
+	   from loading it.
+	 */
+	if (S_ISDIR(sb.st_mode)) {
+		errno = EISDIR;
+		return -1;
+	}
+
+	if (!(sb.st_mode & S_IRUSR)) {
+#ifdef DEBUG
+		printf("Ignoring %s (User-readable bit not set)\n",
+		       libpath);
+#endif
+		errno = EPERM;
+		return -1;
+	}
+
+	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
+		dlclose(handle);
+		errno = EINVAL;
+		return -1;
+	}
+
+	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;
+	}
+
+	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_register(plug) < 0) {
+		dlclose(handle);
+		errno = EINVAL;
+		return -1;
+	} else {
+		printf("Registered plugin %s %s\n",
+		       plug->name, plug->version);
+	}
+
+	return 0;
+}