add plugin support

Makefile

@@ -7,7 +7,7 @@ DEBUG_TYPECAST=0
 
 include Makefile.inc
 
-LIBS=-lc
+LIBS=-lc -ldl
 SHLIB_FILE=libuci.$(SHLIB_EXT).$(VERSION)
 
 define add_feature
@@ -23,6 +23,7 @@ ucimap.o: ucimap.c uci.h uci_config.h ucimap.h uci_list.h
 
 uci_config.h: FORCE
 	@rm -f "$@.tmp"
+	@echo "#define UCI_PREFIX \"$(prefix)\"" > "$@.tmp"
 	$(call add_feature,PLUGIN_SUPPORT)
 	$(call add_feature,DEBUG)
 	$(call add_feature,DEBUG_TYPECAST)
@@ -33,10 +34,10 @@ uci_config.h: FORCE
 	fi
 
 uci: cli.o libuci.$(SHLIB_EXT)
-	$(CC) -o $@ $< -L. -luci
+	$(CC) -o $@ $< -L. -luci $(LIBS)
 
 uci-static: cli.o libuci.a
-	$(CC) $(CFLAGS) -o $@ $^
+	$(CC) $(CFLAGS) -o $@ $^ $(LIBS)
 
 libuci-static.o: libuci.c $(LIBUCI_DEPS)
 	$(CC) $(CFLAGS) -c -o $@ $<

cli.c

@@ -27,6 +27,7 @@ static enum {
 	CLI_FLAG_NOCOMMIT = (1 << 2),
 	CLI_FLAG_BATCH =    (1 << 3),
 	CLI_FLAG_SHOW_EXT = (1 << 4),
+	CLI_FLAG_NOPLUGINS= (1 << 5),
 } flags;
 
 static FILE *input;
@@ -138,6 +139,7 @@ static void uci_usage(void)
 		"\t-c <path>  set the search path for config files (default: /etc/config)\n"
 		"\t-d <str>   set the delimiter for list values in uci show\n"
 		"\t-f <file>  use <file> as input instead of stdin\n"
+		"\t-L         do not load any plugins\n"
 		"\t-m         when importing, merge data into an existing package\n"
 		"\t-n         name unnamed sections on export (default)\n"
 		"\t-N         don't name unnamed sections\n"
@@ -616,7 +618,7 @@ int main(int argc, char **argv)
 		return 1;
 	}
 
-	while((c = getopt(argc, argv, "c:d:f:mnNp:P:sSqX")) != -1) {
+	while((c = getopt(argc, argv, "c:d:f:LmnNp:P:sSqX")) != -1) {
 		switch(c) {
 			case 'c':
 				uci_set_confdir(ctx, optarg);
@@ -631,6 +633,9 @@ int main(int argc, char **argv)
 					return 1;
 				}
 				break;
+			case 'L':
+				flags |= CLI_FLAG_NOPLUGINS;
+				break;
 			case 'm':
 				flags |= CLI_FLAG_MERGE;
 				break;
@@ -675,6 +680,10 @@ int main(int argc, char **argv)
 		uci_usage();
 		return 0;
 	}
+
+	if (!(flags & CLI_FLAG_NOPLUGINS))
+		uci_load_plugins(ctx, NULL);
+
 	ret = uci_cmd(argc - 1, argv + 1);
 	if (input != stdin)
 		fclose(input);

history.c

@@ -419,6 +419,17 @@ int uci_save(struct uci_context *ctx, struct uci_package *p)
 	if ((asprintf(&filename, "%s/%s", ctx->savedir, p->e.name) < 0) || !filename)
 		UCI_THROW(ctx, UCI_ERR_MEM);
 
+	uci_foreach_element(&ctx->hooks, tmp) {
+		struct uci_hook *hook = uci_to_hook(tmp);
+
+		if (!hook->ops->set)
+			continue;
+
+		uci_foreach_element(&p->history, e) {
+			hook->ops->set(hook->ops, p, uci_to_history(e));
+		}
+	}
+
 	ctx->err = 0;
 	UCI_TRAP_SAVE(ctx, done);
 	f = uci_open_stream(ctx, filename, SEEK_END, true, true);

libuci.c

@@ -22,6 +22,8 @@
 #include <string.h>
 #include <stdlib.h>
 #include <stdio.h>
+#include <dlfcn.h>
+#include <glob.h>
 #include "uci.h"
 
 static const char *uci_confdir = UCI_CONFDIR;
@@ -39,6 +41,7 @@ static const char *uci_errstr[] = {
 };
 
 static void uci_cleanup(struct uci_context *ctx);
+static void uci_unload_plugin(struct uci_context *ctx, struct uci_plugin *p);
 
 #include "uci_internal.h"
 #include "util.c"
@@ -56,6 +59,8 @@ struct uci_context *uci_alloc_context(void)
 	uci_list_init(&ctx->root);
 	uci_list_init(&ctx->history_path);
 	uci_list_init(&ctx->backends);
+	uci_list_init(&ctx->hooks);
+	uci_list_init(&ctx->plugins);
 	ctx->flags = UCI_FLAG_STRICT | UCI_FLAG_SAVED_HISTORY;
 
 	ctx->confdir = (char *) uci_confdir;
@@ -86,6 +91,9 @@ void uci_free_context(struct uci_context *ctx)
 		uci_free_element(e);
 	}
 	UCI_TRAP_RESTORE(ctx);
+	uci_foreach_element_safe(&ctx->root, tmp, e) {
+		uci_unload_plugin(ctx, uci_to_plugin(e));
+	}
 	free(ctx);
 
 ignore:
@@ -209,9 +217,16 @@ int uci_commit(struct uci_context *ctx, struct uci_package **package, bool overw
 int uci_load(struct uci_context *ctx, const char *name, struct uci_package **package)
 {
 	struct uci_package *p;
+	struct uci_element *e;
+
 	UCI_HANDLE_ERR(ctx);
 	UCI_ASSERT(ctx, ctx->backend && ctx->backend->load);
 	p = ctx->backend->load(ctx, name);
+	uci_foreach_element(&ctx->hooks, e) {
+		struct uci_hook *h = uci_to_hook(e);
+		if (h->ops->load)
+			h->ops->load(h->ops, p);
+	}
 	if (package)
 		*package = p;
 
@@ -280,3 +295,94 @@ int uci_set_backend(struct uci_context *ctx, const char *name)
 	ctx->backend = uci_to_backend(e);
 	return 0;
 }
+
+int uci_add_hook(struct uci_context *ctx, const struct uci_hook_ops *ops)
+{
+	struct uci_element *e;
+	struct uci_hook *h;
+
+	UCI_HANDLE_ERR(ctx);
+
+	/* check for duplicate elements */
+	uci_foreach_element(&ctx->hooks, e) {
+		h = uci_to_hook(e);
+		if (h->ops == ops)
+			return UCI_ERR_INVAL;
+	}
+
+	h = uci_alloc_element(ctx, hook, "", 0);
+	h->ops = ops;
+	uci_list_init(&h->e.list);
+	uci_list_add(&ctx->hooks, &h->e.list);
+
+	return 0;
+}
+
+int uci_remove_hook(struct uci_context *ctx, const struct uci_hook_ops *ops)
+{
+	struct uci_element *e;
+
+	uci_foreach_element(&ctx->hooks, e) {
+		struct uci_hook *h = uci_to_hook(e);
+		if (h->ops == ops) {
+			uci_list_del(&e->list);
+			return 0;
+		}
+	}
+	return UCI_ERR_NOTFOUND;
+}
+
+int uci_load_plugin(struct uci_context *ctx, const char *filename)
+{
+	struct uci_plugin *p;
+	const struct uci_plugin_ops *ops;
+	void *dlh;
+
+	UCI_HANDLE_ERR(ctx);
+	dlh = dlopen(filename, RTLD_GLOBAL|RTLD_NOW);
+	if (!dlh)
+		UCI_THROW(ctx, UCI_ERR_NOTFOUND);
+
+	ops = dlsym(dlh, "uci_plugin");
+	if (!ops || !ops->attach || (ops->attach(ctx) != 0)) {
+		if (!ops)
+			fprintf(stderr, "No ops\n");
+		else if (!ops->attach)
+			fprintf(stderr, "No attach\n");
+		else
+			fprintf(stderr, "Other weirdness\n");
+		dlclose(dlh);
+		UCI_THROW(ctx, UCI_ERR_INVAL);
+	}
+
+	p = uci_alloc_element(ctx, plugin, filename, 0);
+	p->dlh = dlh;
+	p->ops = ops;
+	uci_list_add(&ctx->plugins, &p->e.list);
+
+	return 0;
+}
+
+static void uci_unload_plugin(struct uci_context *ctx, struct uci_plugin *p)
+{
+	if (p->ops->detach)
+		p->ops->detach(ctx);
+	dlclose(p->dlh);
+	uci_free_element(&p->e);
+}
+
+int uci_load_plugins(struct uci_context *ctx, const char *pattern)
+{
+	glob_t gl;
+	int i;
+
+	if (!pattern)
+		pattern = UCI_PREFIX "/lib/uci_*.so";
+
+	memset(&gl, 0, sizeof(gl));
+	glob(pattern, 0, NULL, &gl);
+	for (i = 0; i < gl.gl_pathc; i++)
+		uci_load_plugin(ctx, gl.gl_pathv[i]);
+
+	return 0;
+}

lua/uci.c

@@ -813,6 +813,20 @@ uci_lua_add_history(lua_State *L)
 	return uci_push_status(L, ctx, false);
 }
 
+static int
+uci_lua_load_plugins(lua_State *L)
+{
+	struct uci_context *ctx;
+	int ret, offset = 0;
+	const char *str = NULL;
+
+	ctx = find_context(L, &offset);
+	if (lua_isstring(L, -1))
+		str = lua_tostring(L, -1);
+	ret = uci_load_plugins(ctx, str);
+	return uci_push_status(L, ctx, false);
+}
+
 static int
 uci_lua_set_savedir(lua_State *L)
 {
@@ -881,6 +895,7 @@ static const luaL_Reg uci[] = {
 	{ "changes", uci_lua_changes },
 	{ "foreach", uci_lua_foreach },
 	{ "add_history", uci_lua_add_history },
+	{ "load_plugins", uci_lua_load_plugins },
 	{ "get_confdir", uci_lua_get_confdir },
 	{ "set_confdir", uci_lua_set_confdir },
 	{ "get_savedir", uci_lua_get_savedir },

uci.h

@@ -56,6 +56,8 @@ struct uci_list
 };
 
 struct uci_ptr;
+struct uci_plugin;
+struct uci_hook_ops;
 struct uci_element;
 struct uci_package;
 struct uci_section;
@@ -283,6 +285,43 @@ extern int uci_set_backend(struct uci_context *ctx, const char *name);
  */
 extern bool uci_validate_text(const char *str);
 
+
+/**
+ * uci_add_hook: add a uci hook
+ * @ctx: uci context
+ * @ops: uci hook ops
+ *
+ * NB: allocated and freed by the caller
+ */
+extern int uci_add_hook(struct uci_context *ctx, const struct uci_hook_ops *ops);
+
+/**
+ * uci_remove_hook: remove a uci hook
+ * @ctx: uci context
+ * @ops: uci hook ops
+ */
+extern int uci_remove_hook(struct uci_context *ctx, const struct uci_hook_ops *ops);
+
+/**
+ * uci_load_plugin: load an uci plugin
+ * @ctx: uci context
+ * @filename: path to the uci plugin
+ *
+ * NB: plugin will be unloaded automatically when the context is freed
+ */
+int uci_load_plugin(struct uci_context *ctx, const char *filename);
+
+/**
+ * uci_load_plugins: load all uci plugins from a directory
+ * @ctx: uci context
+ * @pattern: pattern of uci plugin files (optional)
+ *
+ * if pattern is NULL, then uci_load_plugins will call uci_load_plugin
+ * for uci_*.so in <prefix>/lib/
+ */
+int uci_load_plugins(struct uci_context *ctx, const char *pattern);
+
+
 /* UCI data structures */
 enum uci_type {
 	UCI_TYPE_UNSPEC = 0,
@@ -293,6 +332,8 @@ enum uci_type {
 	UCI_TYPE_PATH = 5,
 	UCI_TYPE_BACKEND = 6,
 	UCI_TYPE_ITEM = 7,
+	UCI_TYPE_HOOK = 8,
+	UCI_TYPE_PLUGIN = 9,
 };
 
 enum uci_option_type {
@@ -354,6 +395,9 @@ struct uci_context
 	bool internal, nested;
 	char *buf;
 	int bufsz;
+
+	struct uci_list hooks;
+	struct uci_list plugins;
 };
 
 struct uci_package
@@ -429,6 +473,31 @@ struct uci_ptr
 	const char *value;
 };
 
+struct uci_hook_ops
+{
+	void (*load)(const struct uci_hook_ops *ops, struct uci_package *p);
+	void (*set)(const struct uci_hook_ops *ops, struct uci_package *p, struct uci_history *e);
+};
+
+struct uci_hook
+{
+	struct uci_element e;
+	const struct uci_hook_ops *ops;
+};
+
+struct uci_plugin_ops
+{
+	int (*attach)(struct uci_context *ctx);
+	void (*detach)(struct uci_context *ctx);
+};
+
+struct uci_plugin
+{
+	struct uci_element e;
+	const struct uci_plugin_ops *ops;
+	void *dlh;
+};
+
 
 /* linked list handling */
 #ifndef offsetof
@@ -499,6 +568,8 @@ struct uci_ptr
 #define uci_type_package UCI_TYPE_PACKAGE
 #define uci_type_section UCI_TYPE_SECTION
 #define uci_type_option UCI_TYPE_OPTION
+#define uci_type_hook UCI_TYPE_HOOK
+#define uci_type_plugin UCI_TYPE_PLUGIN
 
 /* element typecasting */
 #ifdef UCI_DEBUG_TYPECAST
@@ -508,6 +579,8 @@ static const char *uci_typestr[] = {
 	[uci_type_package] = "package",
 	[uci_type_section] = "section",
 	[uci_type_option] = "option",
+	[uci_type_hook] = "hook",
+	[uci_type_plugin] = "plugin",
 };
 
 static void uci_typecast_error(int from, int to)
@@ -529,6 +602,8 @@ BUILD_CAST(history)
 BUILD_CAST(package)
 BUILD_CAST(section)
 BUILD_CAST(option)
+BUILD_CAST(hook)
+BUILD_CAST(plugin)
 
 #else
 #define uci_to_backend(ptr) container_of(ptr, struct uci_backend, e)
@@ -536,6 +611,8 @@ BUILD_CAST(option)
 #define uci_to_package(ptr) container_of(ptr, struct uci_package, e)
 #define uci_to_section(ptr) container_of(ptr, struct uci_section, e)
 #define uci_to_option(ptr)  container_of(ptr, struct uci_option, e)
+#define uci_to_hook(ptr)    container_of(ptr, struct uci_hook, e)
+#define uci_to_plugin(ptr)  container_of(ptr, struct uci_plugin, e)
 #endif
 
 /**