Introduce loadable modules.

* .gitignore: Update.
* configure.ac: Require libtool
Require Grecs tree-api.
* Makefile.am: Incorporate libtool
* bootstrap: Create m4 if it does not exist.
* doc/Makefile.am: Use texi2html
* grecs: Upgrade
* src/module.c: New file.
* src/Makefile.am (wydawca_SOURCES): Add module.c
* src/config.c: Switch callbacks to tree-api.
Add statements for working with modules:
module-load-path, module-prepend-load-path and
module in the global scope and module and
module-config in notify-event blocks.
* src/mail.c (do_notify): Call module_notify if a module
is configured.
* src/tcpwrap.c: Switch callbacks to tree-api.
* src/wydawca.c (main): Load modules.
* src/wydawca.h (notification) <modname>
<modcfg,modnode>: New members.
(module): New struct.
(cb_module,modules_load,module_notify): New functions.
(module_load_path)
(module_prepend_load_path): New globals.

7 files changed, 401 insertions, 82 deletions

diff --git a/src/Makefile.am b/src/Makefile.am
index 2c8f3c4..d7241e9 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -37,2 +37,3 @@ wydawca_SOURCES=\
  meta.c\
+ module.c\
  net.c\
@@ -69,3 +70,3 @@ inc_DATA = $(PP_SETUP_FILE)
 
-LDADD=../grecs/src/libgrecs.a @SQLLIB@ @GPGMELIB@ @MAILUTILS_LIBS@
+LDADD=../grecs/src/libgrecs.a @SQLLIB@ @GPGMELIB@ @MAILUTILS_LIBS@ @LIBLTDL@
 AM_CPPFLAGS= \
@@ -74,2 +75,3 @@ AM_CPPFLAGS= \
  -DLOCALSTATEDIR=\"$(localstatedir)\"\
+ -DWYDAWCA_MODDIR=\"$(WYDAWCA_MODDIR)\"\
  -DDEFAULT_VERSION_INCLUDE_DIR=\"$(incdir)\"\
@@ -77,2 +79,2 @@ AM_CPPFLAGS= \
  -DDEFAULT_PREPROCESSOR="$(DEFAULT_PREPROCESSOR)"
-
+AM_LDFLAGS=-export-dynamic
diff --git a/src/config.c b/src/config.c
index d6f6a89..b381834 100644
--- a/src/config.c
+++ b/src/config.c
@@ -232,6 +232,6 @@ assert_string_arg(grecs_locus_t *locus,
 grecs_value_t *
-get_arg(grecs_locus_t *locus, grecs_value_t *value, unsigned n, int type)
+get_arg(grecs_value_t *value, unsigned n, int type)
 {
-	if (n >= value->v.arg.c) {
-		grecs_error(locus, 0, _("not enough arguments"));
+	if (!value || value->type != GRECS_TYPE_ARRAY || n >= value->v.arg.c) {
+		grecs_error(&value->locus, 0, _("not enough arguments"));
 		return NULL;
@@ -248,8 +248,9 @@ get_arg(grecs_locus_t *locus, grecs_value_t *value, unsigned n, int type)
 static int
-cb_mailer(enum grecs_callback_command cmd,
-	  grecs_locus_t *locus,
-	  void *varptr, grecs_value_t *value, void *cb_data)
+cb_mailer(enum grecs_callback_command cmd, grecs_node_t *node,
+	  void *varptr, void *cb_data)
 {
 	int rc;
-
+	grecs_locus_t *locus = &node->locus;
+	grecs_value_t *value = node->v.value;
+	
 	if (assert_string_arg(locus, cmd, value))
@@ -266,5 +267,4 @@ cb_mailer(enum grecs_callback_command cmd,
 static int
-cb_email_address(enum grecs_callback_command cmd,
-		 grecs_locus_t *locus,
-		 void *varptr, grecs_value_t *value, void *cb_data)
+cb_email_address(enum grecs_callback_command cmd, grecs_node_t *node,
+		 void *varptr, void *cb_data)
 {
@@ -272,2 +272,4 @@ cb_email_address(enum grecs_callback_command cmd,
 	mu_address_t addr = NULL;
+	grecs_locus_t *locus = &node->locus;
+	grecs_value_t *value = node->v.value;
 	struct grecs_list_entry *ep;
@@ -317,5 +319,4 @@ cb_email_address(enum grecs_callback_command cmd,
 static int
-cb_interval(enum grecs_callback_command cmd,
-	    grecs_locus_t *locus,
-	    void *varptr, grecs_value_t *value, void *cb_data)
+cb_interval(enum grecs_callback_command cmd, grecs_node_t *node,
+	    void *varptr, void *cb_data)
 {
@@ -324,2 +325,4 @@ cb_interval(enum grecs_callback_command cmd,
 	const char *endp;
+	grecs_locus_t *locus = &node->locus;
+	grecs_value_t *value = node->v.value;
 
@@ -342,6 +345,8 @@ static int
 cb_absolute_name(enum grecs_callback_command cmd,
-		 grecs_locus_t *locus,
-		 void *varptr, grecs_value_t *value, void *cb_data)
+		 grecs_node_t *node,
+		 void *varptr, void *cb_data)
 {
 	char *word;
+	grecs_locus_t *locus = &node->locus;
+	grecs_value_t *value = node->v.value;
 
@@ -362,4 +367,4 @@ static int
 cb_set_umask(enum grecs_callback_command cmd,
-	     grecs_locus_t *locus,
-	     void *varptr, grecs_value_t *value, void *cb_data)
+	     grecs_node_t *node,
+	     void *varptr, void *cb_data)
 {
@@ -367,2 +372,4 @@ cb_set_umask(enum grecs_callback_command cmd,
 	mode_t m;
+	grecs_locus_t *locus = &node->locus;
+	grecs_value_t *value = node->v.value;
 
@@ -476,7 +483,6 @@ parse_statmask(grecs_locus_t *loc, grecs_value_t *val, unsigned long *pmask)
 static int
-cb_statistics(enum grecs_callback_command cmd,
-	      grecs_locus_t *locus,
-	      void *varptr, grecs_value_t *value, void *cb_data)
+cb_statistics(enum grecs_callback_command cmd, grecs_node_t *node,
+	      void *varptr, void *cb_data)
 {
-	return parse_statmask(locus, value, varptr);
+	return parse_statmask(&node->locus, node->v.value, varptr);
 }
@@ -484,5 +490,4 @@ cb_statistics(enum grecs_callback_command cmd,
 static int
-cb_sql_host(enum grecs_callback_command cmd,
-	    grecs_locus_t *locus,
-	    void *varptr, grecs_value_t *value, void *cb_data)
+cb_sql_host(enum grecs_callback_command cmd, grecs_node_t *node,
+	    void *varptr, void *cb_data)
 {
@@ -490,2 +495,4 @@ cb_sql_host(enum grecs_callback_command cmd,
 	char *p;
+	grecs_locus_t *locus = &node->locus;
+	grecs_value_t *value = node->v.value;
 
@@ -526,5 +533,4 @@ cb_sql_host(enum grecs_callback_command cmd,
 static int
-cb_sql(enum grecs_callback_command cmd,
-       grecs_locus_t *locus,
-       void *varptr, grecs_value_t *value, void *cb_data)
+cb_sql(enum grecs_callback_command cmd, grecs_node_t *node,
+       void *varptr, void *cb_data)
 {
@@ -532,2 +538,4 @@ cb_sql(enum grecs_callback_command cmd,
 	void **pdata = cb_data;
+	grecs_locus_t *locus = &node->locus;
+	grecs_value_t *value = node->v.value;
 
@@ -588,6 +596,8 @@ static struct grecs_keyword sql_kw[] = {
 static int
-cb_syslog_facility(enum grecs_callback_command cmd,
-		   grecs_locus_t *locus,
-		   void *varptr, grecs_value_t *value, void *cb_data)
+cb_syslog_facility(enum grecs_callback_command cmd, grecs_node_t *node,
+		   void *varptr, void *cb_data)
 {
+	grecs_locus_t *locus = &node->locus;
+	grecs_value_t *value = node->v.value;
+
 	if (assert_string_arg(locus, cmd, value))
@@ -603,7 +613,8 @@ cb_syslog_facility(enum grecs_callback_command cmd,
 static int
-cb_define_message(enum grecs_callback_command cmd,
-		  grecs_locus_t *locus,
-		  void *varptr, grecs_value_t *value, void *cb_data)
+cb_define_message(enum grecs_callback_command cmd, grecs_node_t *node,
+		  void *varptr, void *cb_data)
 {
 	const char *ident;
+	grecs_locus_t *locus = &node->locus;
+	grecs_value_t *value = node->v.value;
 
@@ -686,7 +697,8 @@ get_backup_version(grecs_locus_t *locus, const char *ctx, const char *version)
 static int
-cb_backup(enum grecs_callback_command cmd,
-	  grecs_locus_t *locus,
-	  void *varptr, grecs_value_t *value, void *cb_data)
+cb_backup(enum grecs_callback_command cmd, grecs_node_t *node,
+	  void *varptr, void *cb_data)
 {
 	enum backup_type *ptype = varptr;
+	grecs_locus_t *locus = &node->locus;
+	grecs_value_t *value = node->v.value;
 
@@ -712,5 +724,4 @@ static struct grecs_keyword archive_kw[] = {
 static int
-cb_archive(enum grecs_callback_command cmd,
-	   grecs_locus_t *locus,
-	   void *varptr, grecs_value_t *value, void *cb_data)
+cb_archive(enum grecs_callback_command cmd, grecs_node_t *node,
+	   void *varptr, void *cb_data)
 {
@@ -718,2 +729,4 @@ cb_archive(enum grecs_callback_command cmd,
 	void **pdata = cb_data;
+	grecs_locus_t *locus = &node->locus;
+	grecs_value_t *value = node->v.value;
 
@@ -785,7 +798,8 @@ static struct grecs_keyword mail_statistics_kw[] = {
 static int
-cb_event(enum grecs_callback_command cmd,
-	 grecs_locus_t *locus,
-	 void *varptr, grecs_value_t *value, void *cb_data)
+cb_event(enum grecs_callback_command cmd, grecs_node_t *node,
+	 void *varptr, void *cb_data)
 {
 	enum notification_event *pev = varptr;
+	grecs_locus_t *locus = &node->locus;
+	grecs_value_t *value = node->v.value;
 
@@ -798,7 +812,8 @@ cb_event(enum grecs_callback_command cmd,
 static int
-cb_recipient(enum grecs_callback_command cmd,
-	     grecs_locus_t *locus,
-	     void *varptr, grecs_value_t *value, void *cb_data)
+cb_recipient(enum grecs_callback_command cmd, grecs_node_t *node,
+	     void *varptr, void *cb_data)
 {
 	enum notification_target *tgt = varptr;
+	grecs_locus_t *locus = &node->locus;
+	grecs_value_t *value = node->v.value;
 
@@ -828,2 +843,9 @@ static struct grecs_keyword notify_event_kw[] = {
 	  NULL, offsetof(struct notification, sign_keys) },
+	{ "module", N_("name"),
+	  N_("Name of the module to invoke on event"),
+	  grecs_type_string, GRECS_DFLT,
+	  NULL, offsetof(struct notification, modname) },
+	{ "module-config", NULL,
+	  N_("Module-specific configuration data"),
+	  grecs_type_section, GRECS_INAC, NULL, 0, NULL, NULL, NULL },
 	{ NULL }
@@ -832,5 +854,4 @@ static struct grecs_keyword notify_event_kw[] = {
 static int
-cb_notify_event(enum grecs_callback_command cmd,
-		grecs_locus_t *locus,
-		void *varptr, grecs_value_t *value, void *cb_data)
+cb_notify_event(enum grecs_callback_command cmd, grecs_node_t *node,
+		void *varptr, void *cb_data)
 {
@@ -838,2 +859,3 @@ cb_notify_event(enum grecs_callback_command cmd,
 	void **pdata = cb_data;
+	grecs_locus_t *locus = &node->locus;
 
@@ -842,2 +864,3 @@ cb_notify_event(enum grecs_callback_command cmd,
 		ntf = grecs_zalloc(sizeof(*ntf));
+		ntf->modnode = grecs_find_node(node->down, "module-config");
 		*pdata = ntf;
@@ -847,3 +870,3 @@ cb_notify_event(enum grecs_callback_command cmd,
 		ntf = *pdata;
-		if (!ntf->msg)
+		if (!ntf->msg && !ntf->modname)
 			grecs_error(locus, 0, _("missing message definition"));
@@ -878,7 +901,8 @@ string_to_dictionary_type(const char *str)
 static int
-cb_dictionary_type(enum grecs_callback_command cmd,
-		   grecs_locus_t *locus,
-		   void *varptr, grecs_value_t *value, void *cb_data)
+cb_dictionary_type(enum grecs_callback_command cmd, grecs_node_t *node,
+		   void *varptr, void *cb_data)
 {
 	enum dictionary_type *ptype = varptr;
+	grecs_locus_t *locus = &node->locus;
+	grecs_value_t *value = node->v.value;
 
@@ -894,5 +918,4 @@ cb_dictionary_type(enum grecs_callback_command cmd,
 static int
-cb_dictionary_params(enum grecs_callback_command cmd,
-		     grecs_locus_t *locus,
-		     void *varptr, grecs_value_t *value, void *cb_data)
+cb_dictionary_params(enum grecs_callback_command cmd, grecs_node_t *node,
+		     void *varptr, void *cb_data)
 {
@@ -900,2 +923,4 @@ cb_dictionary_params(enum grecs_callback_command cmd,
 	size_t size;
+	grecs_locus_t *locus = &node->locus;
+	grecs_value_t *value = node->v.value;
 
@@ -970,5 +995,4 @@ string_to_dictionary_id(grecs_locus_t *locus,
 static int
-cb_dictionary(enum grecs_callback_command cmd,
-	      grecs_locus_t *locus,
-	      void *varptr, grecs_value_t *value, void *cb_data)
+cb_dictionary(enum grecs_callback_command cmd, grecs_node_t *node,
+	      void *varptr, void *cb_data)
 {
@@ -977,2 +1001,4 @@ cb_dictionary(enum grecs_callback_command cmd,
 	enum dictionary_id id;
+	grecs_locus_t *locus = &node->locus;
+	grecs_value_t *value = node->v.value;
 
@@ -1025,5 +1051,4 @@ cb_dictionary(enum grecs_callback_command cmd,
 static int
-cb_url(enum grecs_callback_command cmd,
-       grecs_locus_t *locus,
-       void *varptr, grecs_value_t *value, void *cb_data)
+cb_url(enum grecs_callback_command cmd, grecs_node_t *node,
+       void *varptr, void *cb_data)
 {
@@ -1031,2 +1056,4 @@ cb_url(enum grecs_callback_command cmd,
 	int rc;
+	grecs_locus_t *locus = &node->locus;
+	grecs_value_t *value = node->v.value;
 
@@ -1081,3 +1108,2 @@ static struct grecs_keyword spool_kw[] = {
 	  NULL, offsetof(struct spool, check_script) },
-
 	{ NULL }
@@ -1086,5 +1112,4 @@ static struct grecs_keyword spool_kw[] = {
 static int
-cb_spool(enum grecs_callback_command cmd,
-	 grecs_locus_t *locus,
-	 void *varptr, grecs_value_t *value, void *cb_data)
+cb_spool(enum grecs_callback_command cmd, grecs_node_t *node,
+	 void *varptr, void *cb_data)
 {
@@ -1093,2 +1118,4 @@ cb_spool(enum grecs_callback_command cmd,
 	int rc, ec, i;
+	grecs_locus_t *locus = &node->locus;
+	grecs_value_t *value = node->v.value;
 
@@ -1167,7 +1194,8 @@ cb_spool(enum grecs_callback_command cmd,
 static int
-cb_user(enum grecs_callback_command cmd,
-	grecs_locus_t *locus,
-	void *varptr, grecs_value_t *value, void *cb_data)
+cb_user(enum grecs_callback_command cmd, grecs_node_t *node,
+	void *varptr, void *cb_data)
 {
 	struct passwd *pw;
+	grecs_locus_t *locus = &node->locus;
+	grecs_value_t *value = node->v.value;
 
@@ -1189,6 +1217,8 @@ cb_user(enum grecs_callback_command cmd,
 static int
-cb_supp_groups(enum grecs_callback_command cmd,
-	       grecs_locus_t *locus,
-	       void *varptr, grecs_value_t *value, void *cb_data)
+cb_supp_groups(enum grecs_callback_command cmd, grecs_node_t *node,
+	       void *varptr, void *cb_data)
 {
+	grecs_locus_t *locus = &node->locus;
+	grecs_value_t *value = node->v.value;
+	
 	if (cmd != grecs_callback_set_value) {
@@ -1246,6 +1276,8 @@ static struct grecs_keyword locking_kw[] = {
 static int
-cb_locking(enum grecs_callback_command cmd,
-	   grecs_locus_t *locus,
-	   void *varptr, grecs_value_t *value, void *cb_data)
+cb_locking(enum grecs_callback_command cmd, grecs_node_t *node,
+	   void *varptr, void *cb_data)
 {
+	grecs_locus_t *locus = &node->locus;
+	grecs_value_t *value = node->v.value;
+
 	if (cmd == grecs_callback_set_value) {
@@ -1263,7 +1295,8 @@ cb_locking(enum grecs_callback_command cmd,
 static int
-cb_upload_version(enum grecs_callback_command cmd,
-		  grecs_locus_t *locus,
-		  void *varptr, grecs_value_t *value, void *cb_data)
+cb_upload_version(enum grecs_callback_command cmd, grecs_node_t *node,
+		  void *varptr, void *cb_data)
 {
 	unsigned *pversion = varptr, n;
+	grecs_locus_t *locus = &node->locus;
+	grecs_value_t *value = node->v.value;
 
@@ -1302,2 +1335,16 @@ static struct grecs_keyword wydawca_kw[] = {
 
+	{ "module-prepend-load-path", N_("path"),
+	  N_("List of directories searched for modules prior to "
+	     "the default module directory"),
+	  grecs_type_string, GRECS_LIST,
+	  &module_prepend_load_path },
+	{ "module-load-path", N_("path"),
+	  N_("List of directories searched for database modules."),
+	  grecs_type_string, GRECS_LIST,
+	  &module_load_path },
+	
+	{ "module", N_("name: string> <path: string"),
+	  N_("Load the specified module"),
+	  grecs_type_string, GRECS_MULT, NULL, 0, cb_module },
+
 	{ "inotify", NULL, N_("Enable or disable inotify support"),
diff --git a/src/mail.c b/src/mail.c
index 2b64501..dd16510 100644
--- a/src/mail.c
+++ b/src/mail.c
@@ -511,2 +511,7 @@ do_notify(struct file_triplet *trp, enum notification_event ev,
 
+	if (ntf->modname) {
+		module_notify(ntf->modname, ntf->modcfg, ev, trp);
+		return;
+	}
+	
 	switch (ntf->tgt) {
diff --git a/src/module.c b/src/module.c
new file mode 100644
index 0000000..41bbb39
--- /dev/null
+++ b/src/module.c
@@ -0,0 +1,236 @@
+/* wydawca - automatic release submission daemon
+   Copyright (C) 2007-2012 Sergey Poznyakoff
+
+   Wydawca 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 3 of the License, or (at your
+   option) any later version.
+
+   Wydawca 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 wydawca. If not, see <http://www.gnu.org/licenses/>. */
+
+#include "wydawca.h"
+#include <ltdl.h>
+
+static struct grecs_symtab *modtab;
+struct grecs_list *module_load_path, *module_prepend_load_path;
+
+static void
+modfree(void *p)
+{
+	struct module *mod = p;
+	free(mod->locus.beg.file);
+	free(mod->locus.end.file);
+	free(mod->path);
+	free(mod->name);
+	free(mod);
+}
+
+static struct module *
+modinstall(const char *name, const char *path, grecs_locus_t *loc)
+{
+	struct module key;
+	struct module *ent;
+	int install = 1;
+
+	if (!modtab) {
+		modtab = grecs_symtab_create(sizeof(struct module),
+					     NULL,
+					     NULL,
+					     NULL,
+					     NULL,
+					     modfree);
+		if (!modtab)
+			grecs_alloc_die();
+	}
+  
+	key.name = (char*) name;
+	ent = grecs_symtab_lookup_or_install(modtab, &key, &install);
+	if (!ent) 
+		grecs_alloc_die();
+	if (install == 0) {
+		grecs_error(loc, 0, _("module %s already declared"), name);
+		grecs_error(&ent->locus, 0, _("previously declared here"));
+		return NULL;
+	}
+	ent->path = grecs_strdup(path);
+	ent->locus.beg.file = grecs_strdup(loc->beg.file);
+	ent->locus.beg.line = loc->beg.line;
+	ent->locus.beg.col = loc->beg.col;
+	ent->locus.end.file = grecs_strdup(loc->end.file);
+	ent->locus.end.line = loc->end.line;
+	ent->locus.end.col = loc->end.col;
+	return ent;
+}
+
+static struct module *
+modlookup(const char *name)
+{
+	struct module key;
+
+	if (!modtab)
+		return NULL;
+  
+	key.name = (char*) name;
+	return grecs_symtab_lookup_or_install(modtab, &key, NULL);
+}
+
+int
+cb_module(enum grecs_callback_command cmd, grecs_node_t *node,
+	  void *varptr, void *cb_data)
+{
+	grecs_value_t *name;
+	grecs_value_t *path;
+	grecs_locus_t *locus = &node->locus;
+	grecs_value_t *value = node->v.value;
+		
+	if (cmd != grecs_callback_set_value) {
+		grecs_error(locus, 0, _("Unexpected block statement"));
+		return 1;
+	}
+
+	if (!(name = get_arg(value, 0, GRECS_TYPE_STRING)))
+		return 1;
+	if (!(path = get_arg(value, 1, GRECS_TYPE_STRING)))
+		return 1;
+	
+	modinstall(name->v.string, path->v.string, locus);
+
+	return 0;
+};
+
+static void *
+resolve_sym(struct module *mod, const char *name)
+{
+	void *sym = lt_dlsym(mod->handle, name);
+	if (!sym) {
+		grecs_error(&mod->locus, 0,
+			    _("module \"%s\" does not define symbol \"%s\""),
+			    mod->name, name);
+	}
+	return sym;
+}
+
+static int
+modload(void *sym, void *data)
+{
+	struct module *mod = sym;
+	lt_dlhandle handle = NULL;
+	lt_dladvise advise = data;
+	
+	if (mod->handle) {
+		grecs_error(&mod->locus, 0, _("already loaded"));
+		return 0;
+	}
+
+	handle = lt_dlopenadvise(mod->path, advise);
+
+	if (!handle) {
+		grecs_error(&mod->locus, 0,
+			    _("cannot load module %s: %s"), mod->path,
+			    lt_dlerror());
+		return 1;
+	}
+	mod->handle = handle;
+	mod->config = resolve_sym(mod, "config");
+	mod->notify = resolve_sym(mod, "notify");
+	
+	return 0;
+}
+
+static int
+spoolmodcfg(struct spool *spool, void *unused)
+{
+	struct notification *np;
+
+	for (np = spool->notification; np; np = np->next) {
+		if (np->modname) {
+			struct module *mod = modlookup(np->modname);
+			if (!mod) {
+				logmsg(LOG_ERR, "spool %s: no such module: %s",
+				       spool->tag, np->modname);
+				return 1;
+			}
+			if (mod->config) {
+				np->modcfg = mod->config(np->modnode);
+				if (!np->modcfg) {
+					logmsg(LOG_ERR,
+					       "spool %s: failed to configure "
+					       "module \"%s\"",
+					       spool->tag, np->modname);
+					return 1;
+				}
+			}
+		}
+	}
+	return 0;
+}
+
+void
+modules_load()
+{
+	lt_dladvise advise = NULL;
+	struct grecs_list_entry *ep;
+	
+	if (lt_dlinit()) {
+		logmsg(LOG_ERR, _("failed to initialize libtool"));
+		return;
+	}
+
+	/* Prepare load path */
+	if (module_prepend_load_path)
+		for (ep = module_prepend_load_path->head; ep; ep = ep->next)
+			lt_dladdsearchdir(ep->data);
+	lt_dladdsearchdir(WYDAWCA_MODDIR);
+	if (module_load_path)
+		for (ep = module_load_path->head; ep; ep = ep->next)
+			lt_dladdsearchdir(ep->data);
+	
+
+	if (lt_dladvise_init(&advise))
+		logmsg(LOG_ERR, "lt_dladvise_init: %s", lt_dlerror());
+	else {
+		if (lt_dladvise_ext(&advise))
+			logmsg(LOG_ERR, "lt_dladvise_ext: %s", lt_dlerror());
+		if (lt_dladvise_global(&advise))
+			logmsg(LOG_ERR, "lt_dladvise_global: %s",
+			       lt_dlerror());
+	}
+	if (grecs_symtab_enumerate(modtab, modload, NULL)) {
+		logmsg(LOG_CRIT, _("some modules failed to load, exiting"));
+		exit(EX_UNAVAILABLE);
+	}
+	lt_dladvise_destroy(&advise);
+
+	if (for_each_spool(spoolmodcfg, NULL)) {
+		logmsg(LOG_CRIT,
+		       _("some modules failed to configure, exiting"));
+		exit(EX_UNAVAILABLE);
+	}
+}
+
+static char *
+getfn(void *trp, const char *fmt)
+{
+	return triplet_expand_param(fmt, trp);
+}
+
+void
+module_notify(const char *name, void *modcfg,
+	      enum notification_event ev, struct file_triplet *trp)
+{
+	struct module *mod = modlookup(name);
+
+	if (!mod) {
+		logmsg(LOG_ERR, "no such module: %s", name);
+		return;
+	}
+	if (mod->notify)
+		mod->notify(modcfg, ev, getfn, trp);
+}
+
diff --git a/src/tcpwrap.c b/src/tcpwrap.c
index 907bc20..4a3e59b 100644
--- a/src/tcpwrap.c
+++ b/src/tcpwrap.c
@@ -28,6 +28,8 @@ int allow_severity = LOG_INFO;
 static int
-cb_syslog_priority(enum grecs_callback_command cmd,
-		   grecs_locus_t * locus,
-		   void *varptr, grecs_value_t * value, void *cb_data)
+cb_syslog_priority(enum grecs_callback_command cmd, grecs_node_t *node,
+		   void *varptr, void *cb_data)
 {
+	grecs_locus_t *locus = &node->locus;
+	grecs_value_t *value = node->v.value;
+	
 	if (assert_string_arg(locus, cmd, value))
diff --git a/src/wydawca.c b/src/wydawca.c
index 42fcea9..f6767b8 100644
--- a/src/wydawca.c
+++ b/src/wydawca.c
@@ -360,2 +360,3 @@ main(int argc, char **argv)
 	config_finish(tree);
+	modules_load();
 	grecs_tree_free(tree);
diff --git a/src/wydawca.h b/src/wydawca.h
index 9e4b2be..8e2f155 100644
--- a/src/wydawca.h
+++ b/src/wydawca.h
@@ -293,2 +293,5 @@ struct notification {
 	const char *msg;
+	char *modname;
+	void *modcfg;
+	grecs_node_t *modnode;
 };
@@ -318,2 +321,23 @@ const char *expand_email_owner(struct metadef *def, void *data);
 
+/* Modules */
+typedef char *(*format_fn)(void *, const char *);
+
+struct module {
+	char *name;
+	char *path;
+	grecs_locus_t locus;
+	void *handle;
+	void *(*config) (grecs_node_t *);
+	int (*notify) (void *, int, format_fn, void *);
+};
+
+int cb_module(enum grecs_callback_command cmd, grecs_node_t *node,
+	      void *varptr, void *cb_data);
+void modules_load(void);
+
+extern struct grecs_list *module_load_path, *module_prepend_load_path;
+void module_notify(const char *name, void *modcfg,
+		   enum notification_event ev, struct file_triplet *tpl);
+
+
 /* Global variables */
@@ -485,2 +509,4 @@ int assert_string_arg(grecs_locus_t *, enum grecs_callback_command,
 		      const grecs_value_t *);
+grecs_value_t *get_arg(grecs_value_t *value, unsigned n, int type);
+