1 files changed, 204 insertions, 0 deletions
diff --git a/agents/virt/common/log.c b/agents/virt/common/log.c
new file mode 100644
index 0000000..61018ed
--- /dev/null
+++ b/agents/virt/common/log.c
@@ -0,0 +1,204 @@
+/**
+ * Syslog wrapper that does not block
+ *
+ * Lon Hohberger, 2009
+ */
+
+#include "config.h"
+
+#include <pthread.h>
+#include <unistd.h>
+#include <sys/syslog.h>
+#include <signal.h>
+#include <string.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <sys/types.h>
+#include <sys/time.h>
+#include <errno.h>
+
+#include "list.h"
+
+struct log_entry {
+	list_head();
+	char *message;
+	int sev;
+	int bufsz;
+};
+
+#define MAX_QUEUE_LENGTH 10
+#define LOGLEN 256
+
+static struct log_entry *_log_entries = NULL;
+static pthread_mutex_t log_mutex = PTHREAD_MUTEX_INITIALIZER;
+static pthread_cond_t log_cond = PTHREAD_COND_INITIALIZER;
+static int log_size = 0;
+static int dropped = 0;
+static pthread_t thread_id = 0;
+
+void __real_syslog(int severity, const char *fmt, ...);
+void __wrap_syslog(int severity, const char *fmt, ...);
+void __wrap_closelog(void);
+
+static void *
+_log_thread(void *arg)
+{
+	struct timeval tv;
+	struct timespec ts;
+	struct log_entry *entry;
+
+	do {
+		gettimeofday(&tv, NULL);
+		ts.tv_sec = tv.tv_sec + 10;
+		ts.tv_nsec = tv.tv_usec;
+
+		pthread_mutex_lock(&log_mutex);
+
+		while (!(entry = _log_entries)) {
+			if (pthread_cond_timedwait(&log_cond,
+						   &log_mutex,
+						   &ts) == ETIMEDOUT)
+				goto out;
+		}
+
+		list_remove(&_log_entries, entry);
+		--log_size;
+		if (log_size < 0)
+			raise(SIGSEGV);
+		pthread_mutex_unlock(&log_mutex);
+
+		__real_syslog(entry->sev, entry->message);
+		free(entry->message);
+		free(entry);
+	} while (1);
+
+out:
+	thread_id = (pthread_t)0;
+	pthread_mutex_unlock(&log_mutex);
+	return NULL;
+}
+
+
+static int
+insert_entry(int sev, char *buf, int bufsz)
+{
+	struct log_entry *lent;
+	pthread_attr_t attrs;
+
+	lent = malloc(sizeof(*lent));
+	if (!lent)
+		return -1;
+	lent->sev = sev;
+	lent->message = buf;
+	lent->bufsz = bufsz;
+
+	pthread_mutex_lock(&log_mutex);
+	if (log_size >= MAX_QUEUE_LENGTH) {
+		free(lent->message);
+		free(lent);
+
+		++dropped;
+		lent = (struct log_entry *)(le(_log_entries)->le_prev);
+
+		lent->sev = LOG_WARNING;
+		snprintf(lent->message, lent->bufsz,
+			 "%d message(s) lost due to syslog load\n",
+			 dropped + 1);
+		/* Dropped +1 because we overwrote a message to
+		 * give the 'dropped' message */
+	} else {
+		++log_size;
+		dropped = 0;
+		list_insert(&_log_entries, lent);
+	}
+
+	if (!thread_id) {
+		pthread_attr_init(&attrs);
+	       	pthread_attr_setinheritsched(&attrs, PTHREAD_INHERIT_SCHED);
+
+		if (pthread_create(&thread_id, &attrs, _log_thread, NULL) < 0)
+			thread_id = 0;
+		pthread_mutex_unlock(&log_mutex);
+	} else {
+		pthread_mutex_unlock(&log_mutex);
+		pthread_cond_signal(&log_cond);
+	}
+
+	return 0;
+}
+
+
+__attribute__((__format__ (__printf__, 2, 0)))
+void
+__wrap_syslog(int severity, const char *fmt, ...)
+{
+	va_list      args;
+	char         *logmsg;
+
+	logmsg = malloc(LOGLEN);
+	if (!logmsg)
+		return;
+	memset(logmsg, 0, LOGLEN);
+
+	va_start(args, fmt);
+	vsnprintf(logmsg + strlen(logmsg), LOGLEN - strlen(logmsg), 
+		  fmt, args);
+	va_end(args);
+
+	insert_entry(severity, logmsg, LOGLEN);
+
+	return;
+}
+
+
+void __real_closelog(void);
+
+void
+__wrap_closelog(void)
+{
+	struct log_entry *lent;
+#ifdef DEBUG
+	int lost = 0;
+#endif
+
+	if (thread_id != 0) {
+		pthread_cancel(thread_id);
+		pthread_join(thread_id, NULL);
+		thread_id = 0;
+	}
+	__real_closelog();
+	while (_log_entries) {
+#ifdef DEBUG
+		++lost;
+#endif
+		lent = _log_entries;
+		list_remove(&_log_entries, lent);
+		free(lent->message);
+		free(lent);
+	}
+
+#ifdef DEBUG
+	printf("%d lost\n", lost);
+#endif
+}
+
+
+#ifdef STANDALONE
+int
+main(int argc, char**argv)
+{
+	int x;
+
+	for (x = 0; x < 100; x++) {
+		syslog(1, "Yo %d\n", x);
+	}
+	sleep(1);
+
+	closelog();
+
+	return 0;
+}
+
+#endif