From ddef591c779ab1b3a2012f1241a49cc87c58c776 Mon Sep 17 00:00:00 2001
From: Heinz Mauelshagen <heinzm@redhat.com>
Date: Wed, 4 May 2005 15:30:51 +0000
Subject: [PATCH] introduced dynamic loading of pthreads lock function

---
 multilog/libmultilog.c         | 35 ++++++++++++++++++++++++++++++++--
 multilog/libmultilog.h         |  1 +
 multilog/tests/test-multilog.c |  5 +++--
 3 files changed, 37 insertions(+), 4 deletions(-)

diff --git a/multilog/libmultilog.c b/multilog/libmultilog.c
index abebb70..3302d81 100644
--- a/multilog/libmultilog.c
+++ b/multilog/libmultilog.c
@@ -40,15 +40,38 @@ struct log_list {
 static LIST_INIT(logs);
 
 /* Mutext for logs accesses. */
-static void *mutex = NULL;
+static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
+static int (*lock_fn)(pthread_mutex_t *) = NULL;
+static int (*unlock_fn)(pthread_mutex_t *) = NULL;
+
 static void lock_mutex(void)
 {
+	if (lock_fn)
+		(*lock_fn)(&mutex);
 }
 
 static void unlock_mutex(void)
 {
+	if (unlock_fn)
+		(*unlock_fn)(&mutex);
 }
 
+static int load_pthread_syms(struct log_data *data)
+{
+	void *dlh;
+
+	if (!(dlh = dlopen("libpthread.so", RTLD_NOW))) {
+		fprintf(stderr, "%s\n", dlerror());
+		return 0;
+	}
+
+	data->info.threaded_syslog.pthread_dlh = dlh;
+
+	return (lock_fn = dlsym(dlh, "pthread_mutex_lock")) &&
+	       (unlock_fn = dlsym(dlh, "pthread_mutex_unlock"));
+}
+
+
 /* Noop logging until the custom log fxn gets registered */
 static void nop_log(void *data, int priority, const char *file, int line,
 		    const char *string)
@@ -119,6 +142,12 @@ static int start_threaded_syslog(struct log_list *logl,
 	log_fxn = dlsym(logdata->info.threaded_syslog.dlh, "write_to_buf");
 	start_syslog = dlsym(logdata->info.threaded_syslog.dlh, "start_syslog_thread");
 
+	if (!log_fxn || !start_syslog ||
+	    !load_pthread_syms(logdata)) {
+		dlclose(logdata->info.threaded_syslog.dlh);
+		return 0;
+	}
+
 	/* FIXME: the timeout here probably can be tweaked */
 	/* FIXME: Probably want to do something if this fails */
 	if (start_syslog(&(logdata->info.threaded_syslog.thread), 100000))
@@ -154,7 +183,6 @@ int multilog_add_type(enum log_type type, struct log_data *data)
 		}
 	}
 
-	list_init(&logl->list); /* Superfluous but safe ;) */
 	logl->type = type;
 	logl->data = data;
 
@@ -249,6 +277,9 @@ void multilog_del_type(enum log_type type, struct log_data *data)
 
 			if ((stop_syslog = dlsym(data->info.threaded_syslog.dlh, "stop_syslog_thread")))
 				stop_syslog(data);
+
+			dlclose(data->info.threaded_syslog.dlh);
+			dlclose(data->info.threaded_syslog.pthread_dlh);
 		}
 
 		free(ll);
diff --git a/multilog/libmultilog.h b/multilog/libmultilog.h
index 4c64148..cdd59ad 100644
--- a/multilog/libmultilog.h
+++ b/multilog/libmultilog.h
@@ -34,6 +34,7 @@ struct file_log {
 struct threaded_syslog_log {
 	pthread_t thread;
 	void *dlh;
+	void *pthread_dlh;
 };
 
 union log_info {
diff --git a/multilog/tests/test-multilog.c b/multilog/tests/test-multilog.c
index 0d7f757..badb61c 100644
--- a/multilog/tests/test-multilog.c
+++ b/multilog/tests/test-multilog.c
@@ -16,7 +16,7 @@ int main(int argc, char **argv)
 
 	multilog_add_type(standard, &logdata);
 
-	for (i = 0; i < 100; i++) {
+	for (i = 0; i < 50; i++) {
 		log_err("Testing really long strings so that we can "
 			"fill the buffer up and show skips %d", i);
 
@@ -36,11 +36,12 @@ int main(int argc, char **argv)
 	 * FIXME: locking on libmultilog bytes here, because the
 	 * threaded log is still active.
 	 */
-	multilog_add_type(standard, NULL);
+	multilog_add_type(standard, &logdata);
 
 	log_err("Test of errors5");
 	log_err("Test of errors6");
 
+	multilog_del_type(standard, NULL);
 	multilog_del_type(threaded_syslog, &logdata);
 
 	exit(EXIT_SUCCESS);
-- 
2.43.5