From 57cfc0aac9f8cc5d00fa1155367dfd055da27761 Mon Sep 17 00:00:00 2001
From: Daniel Hokka Zakrisson <daniel@hozac.com>
Date: Sun, 27 Feb 2011 01:49:00 +0100
Subject: make backend selection at runtime

---
 Makefile               | 40 +++++++++++++++++++---------------------
 antispam-plugin.c      | 29 +++++++++++++++++++++++++++--
 antispam-plugin.h      | 40 ++++++++++++++++++++++------------------
 antispam-storage-1.0.c | 14 +++++++-------
 antispam-storage-1.1.c | 16 ++++++++--------
 antispam-storage-1.2.c | 16 ++++++++--------
 crm114-exec.c          | 25 +++++++++++++++++--------
 dspam-exec.c           | 27 ++++++++++++++++++---------
 mailtrain.c            | 27 ++++++++++++++++++---------
 signature-log.c        | 25 +++++++++++++++++--------
 spool2dir.c            | 27 ++++++++++++++++++---------
 11 files changed, 179 insertions(+), 107 deletions(-)

diff --git a/Makefile b/Makefile
index b833a3f..f405d3d 100644
--- a/Makefile
+++ b/Makefile
@@ -7,6 +7,9 @@ INSTALLDIR ?= $(moduledir)/imap
 # Kill CFLAGS from dovecot-config
 CFLAGS := $(CFLAGSORIG)
 
+backenddir := /usr/lib/dovecot-antispam
+CFLAGS += '-DBACKENDDIR="$(backenddir)"'
+
 # includes/flags we need for building a dovecot plugin
 INCS += -DHAVE_CONFIG_H
 INCS += -I$(DOVECOT)/
@@ -21,6 +24,7 @@ INCS += -I$(DOVECOT)/src/imap/
 
 # output name
 LIBRARY_NAME ?= lib90_$(PLUGINNAME)_plugin.so
+objs = antispam-storage.o antispam-plugin.o
 
 # debug rules
 ifeq ("$(DEBUG)", "stderr")
@@ -37,32 +41,14 @@ ifeq ("$(DEBUG_VERBOSE)", "1")
 CFLAGS += -DCONFIG_DEBUG_VERBOSE
 endif
 
-# backend error check
-ifeq ("$(BACKEND)", "")
-error: verify_config
-	@echo "Error! no backend configured"
-	@false
-endif
-
-# per-backend rules
-ifeq ("$(BACKEND)", "dspam-exec")
-objs += signature.o
-endif
-ifeq ("$(BACKEND)", "signature-log")
-objs += signature.o
-endif
-ifeq ("$(BACKEND)", "crm114-exec")
-objs += signature.o
-endif
+BACKENDS = dspam-exec.so signature-log.so crm114-exec.so mailtrain.so spool2dir.so
 
 # main make rules
 CFLAGS += -fPIC -shared -Wall -Wextra -DPLUGINNAME=$(PLUGINNAME)
 CC ?= cc
 HOSTCC ?= cc
 
-objs += antispam-plugin.o antispam-storage.o $(BACKEND).o
-
-all: verify_config $(LIBRARY_NAME)
+all: verify_config $(LIBRARY_NAME) $(BACKENDS)
 
 antispam-storage.o: antispam-storage.c antispam-storage-*.c $(CONFIG) antispam-plugin.h dovecot-version.h
 	$(CC) -c $(CFLAGS) $(INCS) -o $@ $<
@@ -71,7 +57,7 @@ antispam-storage.o: antispam-storage.c antispam-storage-*.c $(CONFIG) antispam-p
 	$(CC) -c $(CFLAGS) $(INCS) -o $@ $<
 
 $(LIBRARY_NAME): $(objs)
-	$(CC) $(CFLAGS) $(INCS) $(objs) -o $(LIBRARY_NAME) $(LDFLAGS)
+	$(CC) $(CFLAGS) $(INCS) $(objs) -o $(LIBRARY_NAME) $(LDFLAGS) -ldl
 
 dovecot-version: dovecot-version.c $(CONFIG)
 	$(HOSTCC) $(INCS) -o dovecot-version dovecot-version.c
@@ -82,11 +68,23 @@ dovecot-version.h: dovecot-version
 antispam-version.h: version.sh
 	./version.sh > antispam-version.h
 
+dspam-exec.so: dspam-exec.o signature.o
+signature-log.so: signature-log.o signature.o
+crm114-exec.so: crm114-exec.o signature.o
+mailtrain.so: mailtrain.o
+spool2dir.so: spool2dir.o
+
+$(BACKENDS):
+	$(CC) $(CFLAGS) $(INCS) $(LDFLAGS) -shared -o $@ $^
+
+
 clean:
 	rm -f *.so *.o *~ dovecot-version dovecot-version.h antispam-version.h
 
 install: all
 	install -o $(USER) -g $(GROUP) -m 0755 $(LIBRARY_NAME) $(DESTDIR)$(INSTALLDIR)/
+	mkdir -p $(DESTDIR)$(backenddir)
+	install -o $(USER) -g $(GROUP) -m 0755 $(BACKENDS) $(DESTDIR)$(backenddir)/
 
 verify_config:
 	@if [ ! -r $(CONFIG) ]; then \
diff --git a/antispam-plugin.c b/antispam-plugin.c
index 455668d..8a6fb65 100644
--- a/antispam-plugin.c
+++ b/antispam-plugin.c
@@ -27,6 +27,7 @@
 
 #include <stdlib.h>
 #include <ctype.h>
+#include <dlfcn.h>
 
 /* dovecot headers we need */
 #include "lib.h"
@@ -73,12 +74,15 @@ static char **trash_folders[]  = { NULL,		NULL, NULL };
 static char **spam_folders[]   = { default_spam_folders,NULL, NULL };
 static char **unsure_folders[] = { NULL,		NULL, NULL };
 
+void (*antispam_next_hook_mail_storage_created)(struct mail_storage *storage);
 bool antispam_can_append_to_spam = FALSE;
 static char **spam_keywords = NULL;
 
 bool need_keyword_hook;
 bool need_folder_hook;
 
+struct backend *backend = NULL;
+
 /* lower-case string, but keep modified UTF7 unchanged */
 void lowercase_string(const char *in, char *out)
 {
@@ -323,11 +327,32 @@ void PLUGIN_FUNCTION(init)(void)
 		}
 	}
 
+	tmp = get_setting("BACKEND");
+	if (tmp) {
+		void *lib;
+		if (*tmp != '/')
+			tmp = t_strconcat(BACKENDDIR, tmp, ".so", NULL);
+		lib = dlopen(tmp, RTLD_NOW | RTLD_LOCAL);
+		if (!lib) {
+			debug("backend failed to load: %s\n", strerror(errno));
+			exit(3);
+		}
+		backend = dlsym(lib, "antispam_backend");
+		if (!backend) {
+			debug("invalid backend!\n");
+			exit(5);
+		}
+	}
+	else {
+		debug("no backend selected!\n");
+		exit(2);
+	}
+
 	/* set spam_folders to empty to only allow keywords */
 	need_folder_hook = spam_folder_count > 0;
 	need_keyword_hook = !!spam_keywords;
 
-	backend_init(global_pool);
+	backend->init(global_pool);
 
 	antispam_next_hook_mail_storage_created = hook_mail_storage_created;
 	hook_mail_storage_created = antispam_mail_storage_created;
@@ -336,7 +361,7 @@ void PLUGIN_FUNCTION(init)(void)
 void PLUGIN_FUNCTION(deinit)(void)
 {
 	hook_mail_storage_created = antispam_next_hook_mail_storage_created;
-	backend_exit();
+	backend->exit();
 	mempool_unref(&global_pool);
 }
 
diff --git a/antispam-plugin.h b/antispam-plugin.h
index fd8783a..4b95f63 100644
--- a/antispam-plugin.h
+++ b/antispam-plugin.h
@@ -29,22 +29,26 @@ enum classification {
 	CLASS_SPAM,
 };
 
-void backend_init(pool_t pool);
-void backend_exit(void);
-/*
- * Handle mail; parameters are
- *  - t: transaction context
- *  - ast: transaction context from backend_start()
- *  - mail: the message
- *  - wanted: the wanted classification determined by the user
- */
-int backend_handle_mail(struct mailbox_transaction_context *t,
-			struct antispam_transaction_context *ast,
-			struct mail *mail, enum classification wanted);
-struct antispam_transaction_context *backend_start(struct mailbox *box);
-void backend_rollback(struct antispam_transaction_context *ast);
-int backend_commit(struct mailbox_transaction_context *ctx,
-		   struct antispam_transaction_context *ast);
+struct backend {
+	void (*init)(pool_t pool);
+	void (*exit)(void);
+	/*
+	 * Handle mail; parameters are
+	 *  - t: transaction context
+	 *  - ast: transaction context from backend_start()
+	 *  - mail: the message
+	 *  - wanted: the wanted classification determined by the user
+	 */
+	int (*handle_mail)(struct mailbox_transaction_context *t,
+			   struct antispam_transaction_context *ast,
+			   struct mail *mail, enum classification wanted);
+	struct antispam_transaction_context *(*start)(struct mailbox *box);
+	void (*rollback)(struct antispam_transaction_context *ast);
+	int (*commit)(struct mailbox_transaction_context *ctx,
+		      struct antispam_transaction_context *ast);
+};
+
+extern struct backend *backend;
 
 #ifdef CONFIG_DEBUG
 void debug(const char *fmt, ...) __attribute__ ((format (printf, 1, 2)));
@@ -70,12 +74,12 @@ static inline void debug_verbose(const char *fmt __attribute__((unused)), ...)
 #endif
 
 void antispam_mail_storage_created(struct mail_storage *storage);
-void (*antispam_next_hook_mail_storage_created)(struct mail_storage *storage);
+extern void (*antispam_next_hook_mail_storage_created)(struct mail_storage *storage);
 bool mailbox_is_spam(struct mailbox *box);
 bool mailbox_is_trash(struct mailbox *box);
 bool mailbox_is_unsure(struct mailbox *box);
 const char *get_setting(const char *name);
-bool antispam_can_append_to_spam;
+extern bool antispam_can_append_to_spam;
 bool keyword_is_spam(const char *keyword);
 
 extern bool need_keyword_hook;
diff --git a/antispam-storage-1.0.c b/antispam-storage-1.0.c
index 1651281..3112a22 100644
--- a/antispam-storage-1.0.c
+++ b/antispam-storage-1.0.c
@@ -119,8 +119,8 @@ antispam_copy(struct mailbox_transaction_context *t, struct mail *mail,
 	if (asbox->save_hack || asbox->movetype == MMT_UNINTERESTING)
 		ret = 0;
 	else
-		ret = backend_handle_mail(t, ast, copy_dest_mail,
-					  move_to_class(asbox->movetype));
+		ret = backend->handle_mail(t, ast, copy_dest_mail,
+					   move_to_class(asbox->movetype));
 
 	/*
 	 * Both save_hack and movetype are only valid within a copy operation,
@@ -231,8 +231,8 @@ static int antispam_save_finish(struct mail_save_context *ctx,
 		}
 		/* fall through */
 	default:
-		ret = backend_handle_mail(ctx->transaction, ast, save_dest_mail,
-					  move_to_class(asbox->movetype));
+		ret = backend->handle_mail(ctx->transaction, ast, save_dest_mail,
+					   move_to_class(asbox->movetype));
 	}
 
 	if (save_dest_mail != dest_mail)
@@ -245,7 +245,7 @@ antispam_transaction_begin(struct mailbox *box)
 {
 	struct antispam_transaction_context *ast;
 
-	ast = backend_start(box);
+	ast = backend->start(box);
 	i_assert(ast != NULL);
 
 	return ast;
@@ -256,7 +256,7 @@ antispam_transaction_rollback(struct antispam_transaction_context **_ast)
 {
 	struct antispam_transaction_context *ast = *_ast;
 
-	backend_rollback(ast);
+	backend->rollback(ast);
 	*_ast = NULL;
 }
 
@@ -267,7 +267,7 @@ antispam_transaction_commit(struct mailbox_transaction_context *ctx,
 	struct antispam_transaction_context *ast = *_ast;
 	int ret;
 
-	ret = backend_commit(ctx, ast);
+	ret = backend->commit(ctx, ast);
 	*_ast = NULL;
 	return ret;
 }
diff --git a/antispam-storage-1.1.c b/antispam-storage-1.1.c
index 80c80e3..e21ac82 100644
--- a/antispam-storage-1.1.c
+++ b/antispam-storage-1.1.c
@@ -127,8 +127,8 @@ antispam_copy(struct mailbox_transaction_context *t, struct mail *mail,
 	if (asbox->save_hack || asbox->movetype == MMT_UNINTERESTING)
 		ret = 0;
 	else
-		ret = backend_handle_mail(t, ast->backendctx, dest_mail,
-					  move_to_class(asbox->movetype));
+		ret = backend->handle_mail(t, ast->backendctx, dest_mail,
+					   move_to_class(asbox->movetype));
 
 	/*
 	 * Both save_hack and movetype are only valid within a copy operation,
@@ -247,9 +247,9 @@ static int antispam_save_finish(struct mail_save_context *ctx)
 		}
 		/* fall through */
 	default:
-		ret = backend_handle_mail(ctx->transaction, ast->backendctx,
-					  dest_mail,
-					  move_to_class(asbox->movetype));
+		ret = backend->handle_mail(ctx->transaction, ast->backendctx,
+					   dest_mail,
+					   move_to_class(asbox->movetype));
 	}
 
 	return ret;
@@ -260,7 +260,7 @@ antispam_transaction_begin(struct mailbox *box)
 {
 	struct antispam_transaction_context *ast;
 
-	ast = backend_start(box);
+	ast = backend->start(box);
 	i_assert(ast != NULL);
 
 	return ast;
@@ -271,7 +271,7 @@ antispam_transaction_rollback(struct antispam_transaction_context **_ast)
 {
 	struct antispam_transaction_context *ast = *_ast;
 
-	backend_rollback(ast);
+	backend->rollback(ast);
 	*_ast = NULL;
 }
 
@@ -282,7 +282,7 @@ antispam_transaction_commit(struct mailbox_transaction_context *ctx,
 	struct antispam_transaction_context *ast = *_ast;
 	int ret;
 
-	ret = backend_commit(ctx, ast);
+	ret = backend->commit(ctx, ast);
 	*_ast = NULL;
 	return ret;
 }
diff --git a/antispam-storage-1.2.c b/antispam-storage-1.2.c
index 54b8f7b..2c11ce7 100644
--- a/antispam-storage-1.2.c
+++ b/antispam-storage-1.2.c
@@ -126,8 +126,8 @@ antispam_copy(struct mail_save_context *ctx, struct mail *mail)
 	if (asbox->save_hack || asbox->movetype == MMT_UNINTERESTING)
 		ret = 0;
 	else
-		ret = backend_handle_mail(t, ast->backendctx, ctx->dest_mail,
-					  move_to_class(asbox->movetype));
+		ret = backend->handle_mail(t, ast->backendctx, ctx->dest_mail,
+					   move_to_class(asbox->movetype));
 
 	/*
 	 * Both save_hack and movetype are only valid within a copy operation,
@@ -237,9 +237,9 @@ static int antispam_save_finish(struct mail_save_context *ctx)
 		}
 		/* fall through */
 	default:
-		ret = backend_handle_mail(ctx->transaction, ast->backendctx,
-					  dest_mail,
-					  move_to_class(asbox->movetype));
+		ret = backend->handle_mail(ctx->transaction, ast->backendctx,
+					   dest_mail,
+					   move_to_class(asbox->movetype));
 	}
 
 	return ret;
@@ -250,7 +250,7 @@ antispam_transaction_begin(struct mailbox *box)
 {
 	struct antispam_transaction_context *ast;
 
-	ast = backend_start(box);
+	ast = backend->start(box);
 	i_assert(ast != NULL);
 
 	return ast;
@@ -261,7 +261,7 @@ antispam_transaction_rollback(struct antispam_transaction_context **_ast)
 {
 	struct antispam_transaction_context *ast = *_ast;
 
-	backend_rollback(ast);
+	backend->rollback(ast);
 	*_ast = NULL;
 }
 
@@ -272,7 +272,7 @@ antispam_transaction_commit(struct mailbox_transaction_context *ctx,
 	struct antispam_transaction_context *ast = *_ast;
 	int ret;
 
-	ret = backend_commit(ctx, ast);
+	ret = backend->commit(ctx, ast);
 	*_ast = NULL;
 	return ret;
 }
diff --git a/crm114-exec.c b/crm114-exec.c
index 7727409..f4245dd 100644
--- a/crm114-exec.c
+++ b/crm114-exec.c
@@ -129,7 +129,7 @@ struct antispam_transaction_context {
 	struct siglist *siglist;
 };
 
-struct antispam_transaction_context *
+static struct antispam_transaction_context *
 backend_start(struct mailbox *box __attr_unused__)
 {
 	struct antispam_transaction_context *ast;
@@ -139,13 +139,13 @@ backend_start(struct mailbox *box __attr_unused__)
 	return ast;
 }
 
-void backend_rollback(struct antispam_transaction_context *ast)
+static void backend_rollback(struct antispam_transaction_context *ast)
 {
 	signature_list_free(&ast->siglist);
 	i_free(ast);
 }
 
-int backend_commit(struct mailbox_transaction_context *ctx,
+static int backend_commit(struct mailbox_transaction_context *ctx,
 		   struct antispam_transaction_context *ast)
 {
 	struct siglist *item = ast->siglist;
@@ -167,14 +167,14 @@ int backend_commit(struct mailbox_transaction_context *ctx,
 	return ret;
 }
 
-int backend_handle_mail(struct mailbox_transaction_context *t,
-			struct antispam_transaction_context *ast,
-			struct mail *mail, enum classification want)
+static int backend_handle_mail(struct mailbox_transaction_context *t,
+			       struct antispam_transaction_context *ast,
+			       struct mail *mail, enum classification want)
 {
 	return signature_extract_to_list(t, mail, &ast->siglist, want);
 }
 
-void backend_init(pool_t pool)
+static void backend_init(pool_t pool)
 {
 	const char *tmp;
 	int i;
@@ -198,6 +198,15 @@ void backend_init(pool_t pool)
 	signature_init();
 }
 
-void backend_exit(void)
+static void backend_exit(void)
 {
 }
+
+struct backend antispam_backend = {
+  .init = backend_init,
+  .exit = backend_exit,
+  .handle_mail = backend_handle_mail,
+  .start = backend_start,
+  .rollback = backend_rollback,
+  .commit = backend_commit,
+};
diff --git a/dspam-exec.c b/dspam-exec.c
index ecfb9f1..ed706d7 100644
--- a/dspam-exec.c
+++ b/dspam-exec.c
@@ -163,7 +163,7 @@ struct antispam_transaction_context {
 	struct siglist *siglist;
 };
 
-struct antispam_transaction_context *
+static struct antispam_transaction_context *
 backend_start(struct mailbox *box __attr_unused__)
 {
 	struct antispam_transaction_context *ast;
@@ -173,14 +173,14 @@ backend_start(struct mailbox *box __attr_unused__)
 	return ast;
 }
 
-void backend_rollback(struct antispam_transaction_context *ast)
+static void backend_rollback(struct antispam_transaction_context *ast)
 {
 	signature_list_free(&ast->siglist);
 	i_free(ast);
 }
 
-int backend_commit(struct mailbox_transaction_context *ctx,
-		   struct antispam_transaction_context *ast)
+static int backend_commit(struct mailbox_transaction_context *ctx,
+			  struct antispam_transaction_context *ast)
 {
 	struct siglist *item = ast->siglist;
 	int ret = 0;
@@ -201,9 +201,9 @@ int backend_commit(struct mailbox_transaction_context *ctx,
 	return ret;
 }
 
-int backend_handle_mail(struct mailbox_transaction_context *t,
-			struct antispam_transaction_context *ast,
-			struct mail *mail, enum classification want)
+static int backend_handle_mail(struct mailbox_transaction_context *t,
+			       struct antispam_transaction_context *ast,
+			       struct mail *mail, enum classification want)
 {
 	const char *const *result = NULL;
 	int i;
@@ -224,7 +224,7 @@ int backend_handle_mail(struct mailbox_transaction_context *t,
 	return signature_extract_to_list(t, mail, &ast->siglist, want);
 }
 
-void backend_init(pool_t pool)
+static void backend_init(pool_t pool)
 {
 	const char *tmp;
 	int i;
@@ -263,6 +263,15 @@ void backend_init(pool_t pool)
 	signature_init();
 }
 
-void backend_exit(void)
+static void backend_exit(void)
 {
 }
+
+struct backend antispam_backend = {
+  .init = backend_init,
+  .exit = backend_exit,
+  .handle_mail = backend_handle_mail,
+  .start = backend_start,
+  .rollback = backend_rollback,
+  .commit = backend_commit,
+};
diff --git a/mailtrain.c b/mailtrain.c
index 5529f03..276eb4a 100644
--- a/mailtrain.c
+++ b/mailtrain.c
@@ -101,7 +101,7 @@ struct antispam_transaction_context {
 	int tmplen;
 };
 
-struct antispam_transaction_context *
+static struct antispam_transaction_context *
 backend_start(struct mailbox *box __attr_unused__)
 {
 	struct antispam_transaction_context *ast;
@@ -178,7 +178,7 @@ static void clear_tmpdir(struct antispam_transaction_context *ast)
 	t_pop();
 }
 
-void backend_rollback(struct antispam_transaction_context *ast)
+static void backend_rollback(struct antispam_transaction_context *ast)
 {
 	if (ast->tmpdir) {
 		/* clear it! */
@@ -189,8 +189,8 @@ void backend_rollback(struct antispam_transaction_context *ast)
 	i_free(ast);
 }
 
-int backend_commit(struct mailbox_transaction_context *ctx,
-		   struct antispam_transaction_context *ast)
+static int backend_commit(struct mailbox_transaction_context *ctx,
+			  struct antispam_transaction_context *ast)
 {
 	int ret;
 
@@ -209,9 +209,9 @@ int backend_commit(struct mailbox_transaction_context *ctx,
 	return ret;
 }
 
-int backend_handle_mail(struct mailbox_transaction_context *t,
-			struct antispam_transaction_context *ast,
-			struct mail *mail, enum classification wanted)
+static int backend_handle_mail(struct mailbox_transaction_context *t,
+			       struct antispam_transaction_context *ast,
+			       struct mail *mail, enum classification wanted)
 {
 	struct istream *mailstream;
 	struct ostream *outstream;
@@ -310,7 +310,7 @@ int backend_handle_mail(struct mailbox_transaction_context *t,
 	return ret;
 }
 
-void backend_init(pool_t pool __attr_unused__)
+static void backend_init(pool_t pool __attr_unused__)
 {
 	const char *tmp;
 	int i;
@@ -349,6 +349,15 @@ void backend_init(pool_t pool __attr_unused__)
 	debug("mail backend tmpdir %s\n", tmpdir);
 }
 
-void backend_exit(void)
+static void backend_exit(void)
 {
 }
+
+struct backend antispam_backend = {
+  .init = backend_init,
+  .exit = backend_exit,
+  .handle_mail = backend_handle_mail,
+  .start = backend_start,
+  .rollback = backend_rollback,
+  .commit = backend_commit,
+};
diff --git a/signature-log.c b/signature-log.c
index 85617f1..1cfc956 100644
--- a/signature-log.c
+++ b/signature-log.c
@@ -44,7 +44,7 @@ struct antispam_transaction_context {
 	struct dict_transaction_context *dict_ctx;
 };
 
-struct antispam_transaction_context *
+static struct antispam_transaction_context *
 backend_start(struct mailbox *box __attr_unused__)
 {
 	struct antispam_transaction_context *ast;
@@ -59,7 +59,7 @@ backend_start(struct mailbox *box __attr_unused__)
 	return ast;
 }
 
-void backend_rollback(struct antispam_transaction_context *ast)
+static void backend_rollback(struct antispam_transaction_context *ast)
 {
 	if (ast->dict) {
 //		dict_transaction_rollback(ast->dict_ctx);
@@ -69,7 +69,7 @@ void backend_rollback(struct antispam_transaction_context *ast)
 	i_free(ast);
 }
 
-int backend_commit(struct mailbox_transaction_context *ctx __attr_unused__,
+static int backend_commit(struct mailbox_transaction_context *ctx __attr_unused__,
 		   struct antispam_transaction_context *ast)
 {
 	int ret = 0;
@@ -84,9 +84,9 @@ int backend_commit(struct mailbox_transaction_context *ctx __attr_unused__,
 	return ret;
 }
 
-int backend_handle_mail(struct mailbox_transaction_context *t,
-			struct antispam_transaction_context *ast,
-			struct mail *mail, enum classification wanted)
+static int backend_handle_mail(struct mailbox_transaction_context *t,
+			       struct antispam_transaction_context *ast,
+			       struct mail *mail, enum classification wanted)
 {
 	const char *signature;
 	int ret;
@@ -137,7 +137,7 @@ int backend_handle_mail(struct mailbox_transaction_context *t,
 	return ret;
 }
 
-void backend_init(pool_t pool __attr_unused__)
+static void backend_init(pool_t pool __attr_unused__)
 {
 	const char *tmp;
 
@@ -156,6 +156,15 @@ void backend_init(pool_t pool __attr_unused__)
 	signature_init();
 }
 
-void backend_exit(void)
+static void backend_exit(void)
 {
 }
+
+struct backend antispam_backend = {
+  .init = backend_init,
+  .exit = backend_exit,
+  .handle_mail = backend_handle_mail,
+  .start = backend_start,
+  .rollback = backend_rollback,
+  .commit = backend_commit,
+};
diff --git a/spool2dir.c b/spool2dir.c
index aa53e71..2c4b547 100644
--- a/spool2dir.c
+++ b/spool2dir.c
@@ -112,22 +112,22 @@ struct antispam_transaction_context {
 };
 
 
-void backend_rollback(struct antispam_transaction_context *ast)
+static void backend_rollback(struct antispam_transaction_context *ast)
 {
 	i_free(ast);
 }
 
-int backend_commit(struct mailbox_transaction_context *ctx __attr_unused__,
-		   struct antispam_transaction_context *ast)
+static int backend_commit(struct mailbox_transaction_context *ctx __attr_unused__,
+			  struct antispam_transaction_context *ast)
 {
 	i_free(ast);
 
 	return 0;
 }
 
-int backend_handle_mail(struct mailbox_transaction_context *t,
-			struct antispam_transaction_context *ast,
-			struct mail *mail, enum classification wanted)
+static int backend_handle_mail(struct mailbox_transaction_context *t,
+			       struct antispam_transaction_context *ast,
+			       struct mail *mail, enum classification wanted)
 {
 	struct istream *mailstream;
 	struct ostream *outstream;
@@ -232,7 +232,7 @@ int backend_handle_mail(struct mailbox_transaction_context *t,
 	return ret;
 }
 
-void backend_init(pool_t pool __attr_unused__)
+static void backend_init(pool_t pool __attr_unused__)
 {
 	if((spamspool = get_setting("SPOOL2DIR_SPAM")))
 		debug("spool2dir spamspool %s\n", spamspool);
@@ -241,7 +241,7 @@ void backend_init(pool_t pool __attr_unused__)
 		debug("spool2dir hamspool %s\n", hamspool);
 }
 
-struct antispam_transaction_context *
+static struct antispam_transaction_context *
  backend_start(struct mailbox *box __attr_unused__)
 {
 	struct antispam_transaction_context *ast;
@@ -254,6 +254,15 @@ struct antispam_transaction_context *
 }
 
 
-void backend_exit(void)
+static void backend_exit(void)
 {
 }
+
+struct backend antispam_backend = {
+  .init = backend_init,
+  .exit = backend_exit,
+  .handle_mail = backend_handle_mail,
+  .start = backend_start,
+  .rollback = backend_rollback,
+  .commit = backend_commit,
+};
-- 
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