From: Stephan Bosch <stephan.bosch@dovecot.fi>
Date: Sun, 30 Jun 2019 09:41:58 +0000 (+0200)
Subject: lib: lib-event - Add support for amending the event log message in a callback.
X-Git-Tag: 2.3.9~399
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=51b5367db82de4055313bcbb9dddace1b76d3fb3;p=thirdparty%2Fdovecot%2Fcore.git

lib: lib-event - Add support for amending the event log message in a callback.
---

diff --git a/src/lib/event-log.c b/src/lib/event-log.c
index b3f15bd16b..eb672ed1cb 100644
--- a/src/lib/event-log.c
+++ b/src/lib/event-log.c
@@ -95,18 +95,50 @@ void e_log(struct event *event, enum log_type level,
 }
 
 struct event_get_log_message_context {
+	const struct event_log_params *params;
+
 	string_t *log_prefix;
+	const char *message;
 	bool replace_prefix;
 	unsigned int type_pos;
 };
 
-static bool
+static bool ATTR_FORMAT(3, 0)
 event_get_log_message(struct event *event,
-		      struct event_get_log_message_context *glmctx)
+		      struct event_get_log_message_context *glmctx,
+		      const char *fmt, va_list args)
 {
 	const char *prefix = event->log_prefix;
 	bool ret = FALSE;
 
+	/* Call the message amendment callback for this event if there is one.
+	 */
+	if (event->log_message_callback != NULL) {
+		const char *in_message;
+
+		/* construct the log message composed by children and arguments
+		 */
+		if (glmctx->message == NULL) {
+			str_vprintfa(glmctx->log_prefix, fmt, args);
+			in_message = str_c(glmctx->log_prefix);
+		} else if (str_len(glmctx->log_prefix) == 0) {
+			in_message = glmctx->message;
+		} else {
+			str_append(glmctx->log_prefix, glmctx->message);
+			in_message = str_c(glmctx->log_prefix);
+		}
+
+		/* reformat the log message */
+		glmctx->message = event->log_message_callback(
+			event->log_message_callback_context,
+			glmctx->params->log_type, in_message);
+
+		/* continue with a cleared prefix buffer (as prefix is now part
+		   of *message_r). */
+		str_truncate(glmctx->log_prefix, 0);
+		ret = TRUE;
+	}
+
 	if (event->log_prefix_callback != NULL) {
 		prefix = event->log_prefix_callback(
 			event->log_prefix_callback_context);
@@ -120,10 +152,8 @@ event_get_log_message(struct event *event,
 		/* this event replaces all parent log prefixes */
 		glmctx->replace_prefix = TRUE;
 		glmctx->type_pos = (prefix == NULL ? 0 : strlen(prefix));
-	} else if (event->parent == NULL) {
-		/* append to default log prefix, don't replace it */
-	} else {
-		if (event_get_log_message(event->parent, glmctx))
+	} else if (event->parent != NULL) {
+		if (event_get_log_message(event->parent, glmctx, fmt, args))
 			ret = TRUE;
 	}
 	return ret;
@@ -208,18 +238,25 @@ event_logv_params(struct event *event, const struct event_log_params *params,
 		abort_after_event = TRUE;
 
 	i_zero(&glmctx);
+	glmctx.params = params;
 	glmctx.log_prefix = t_str_new(64);
-	if (!event_get_log_message(event, &glmctx)) {
+	if (!event_get_log_message(event, &glmctx, fmt, args)) {
 		/* keep log prefix as it is */
 		event_vsend(event, &ctx, fmt, args);
 	} else if (glmctx.replace_prefix) {
 		/* event overrides the log prefix (even if it's "") */
 		ctx.log_prefix = str_c(glmctx.log_prefix);
 		ctx.log_prefix_type_pos = glmctx.type_pos;
-		event_vsend(event, &ctx, fmt, args);
+		if (glmctx.message != NULL)
+			event_send(event, &ctx, "%s", glmctx.message);
+		else
+			event_vsend(event, &ctx, fmt, args);
 	} else {
 		/* append to log prefix, but don't fully replace it */
-		str_vprintfa(glmctx.log_prefix, fmt, args);
+		if (glmctx.message != NULL)
+			str_append(glmctx.log_prefix, glmctx.message);
+		else
+			str_vprintfa(glmctx.log_prefix, fmt, args);
 		event_send(event, &ctx, "%s", str_c(glmctx.log_prefix));
 	}
 	if (abort_after_event)
diff --git a/src/lib/lib-event-private.h b/src/lib/lib-event-private.h
index 7b62e25421..7adc1de6f6 100644
--- a/src/lib/lib-event-private.h
+++ b/src/lib/lib-event-private.h
@@ -14,6 +14,8 @@ struct event {
 	char *log_prefix;
 	event_log_prefix_callback_t *log_prefix_callback;
 	void *log_prefix_callback_context;
+	event_log_message_callback_t *log_message_callback;
+	void *log_message_callback_context;
 	enum log_type min_log_level;
 	bool log_prefix_from_system_pool:1;
 	bool log_prefix_replace:1;
diff --git a/src/lib/lib-event.c b/src/lib/lib-event.c
index c88c1f7743..7ea2acf799 100644
--- a/src/lib/lib-event.c
+++ b/src/lib/lib-event.c
@@ -485,6 +485,17 @@ event_set_log_prefix_callback(struct event *event,
 	return event;
 }
 
+#undef event_set_log_message_callback
+struct event *
+event_set_log_message_callback(struct event *event,
+			       event_log_message_callback_t *callback,
+			       void *context)
+{
+	event->log_message_callback = callback;
+	event->log_message_callback_context = context;
+	return event;
+}
+
 struct event *
 event_set_name(struct event *event, const char *name)
 {
diff --git a/src/lib/lib-event.h b/src/lib/lib-event.h
index 690b0fd3a8..a1c6820f0f 100644
--- a/src/lib/lib-event.h
+++ b/src/lib/lib-event.h
@@ -77,7 +77,11 @@ struct event_passthrough {
 	struct event *(*event)(void);
 };
 
-typedef const char *event_log_prefix_callback_t(void *context);
+typedef const char *
+event_log_prefix_callback_t(void *context);
+typedef const char *
+event_log_message_callback_t(void *context, enum log_type log_type,
+			     const char *message);
 
 /* Returns TRUE if the event has all the categories that the "other" event has (and maybe more). */
 bool event_has_all_categories(struct event *event, const struct event *other);
@@ -169,7 +173,8 @@ struct event *event_get_global(void);
 struct event *
 event_set_append_log_prefix(struct event *event, const char *prefix);
 /* Replace the full log prefix string for this event. The parent events' log
-   prefixes won't be used.
+   prefixes won't be used. Also, any parent event's message amendment callback
+   is not used.
 
    Clears log_prefix callback.
 */
@@ -185,6 +190,17 @@ struct event *event_set_log_prefix_callback(struct event *event,
 	event_set_log_prefix_callback(event, replace, (event_log_prefix_callback_t*)callback, \
 		context - CALLBACK_TYPECHECK(callback, const char *(*)(typeof(context))))
 
+/* Sets event message amendment callback */
+struct event *event_set_log_message_callback(struct event *event,
+					     event_log_message_callback_t *callback,
+					     void *context);
+#define event_set_log_message_callback(event, callback, context) \
+	event_set_log_message_callback(event, \
+		(event_log_message_callback_t*)callback, \
+		context - CALLBACK_TYPECHECK(callback, \
+			const char *(*)(typeof(context), enum log_type, \
+					const char *)))
+
 /* Set the event's name. The name is specific to a single sending of an event,
    and it'll be automatically cleared once the event is sent. This should
    typically be used only in a parameter to e_debug(), etc. */