liblog: Add android_set_log_frontend
android_set_log_frontend allows one to select LOGGER_DEFAULT,
LOGGER_LOGD or LOGGER_NULL, the latter allows a runtime mechanism to
turn logging on or off. LOGGER_DEFAULT is LOGGER_LOGD.
Test: gTest liblog-unit-tests notably liblog.android_set_log_frontend
and liblog-benchmarks before and after.
Bug: 27405083
Change-Id: I365dbee9f7d83112da0ef8d1cace748d247773c8
diff --git a/liblog/logger_write.c b/liblog/logger_write.c
index 2599a53..bff77f8 100644
--- a/liblog/logger_write.c
+++ b/liblog/logger_write.c
@@ -25,6 +25,7 @@
#endif
#include <log/event_tag_map.h>
+#include <log/log_frontend.h>
#include <private/android_filesystem_config.h>
#include <private/android_logger.h>
@@ -618,3 +619,67 @@
return write_to_log(LOG_ID_SECURITY, vec, 4);
}
+
+static int __write_to_log_null(log_id_t log_id, struct iovec* vec, size_t nr)
+{
+ size_t len, i;
+
+ if ((log_id < LOG_ID_MIN) || (log_id >= LOG_ID_MAX)) {
+ return -EINVAL;
+ }
+
+ for (len = i = 0; i < nr; ++i) {
+ len += vec[i].iov_len;
+ }
+ if (!len) {
+ return -EINVAL;
+ }
+ return len;
+}
+
+/* Following functions need access to our internal write_to_log status */
+
+LIBLOG_ABI_PUBLIC int android_set_log_frontend(int frontend_flag)
+{
+ if (frontend_flag < 0) {
+ return -EINVAL;
+ }
+
+ __android_log_lock();
+
+ if (frontend_flag & LOGGER_NULL) {
+ write_to_log = __write_to_log_null;
+
+ __android_log_unlock();
+
+ return LOGGER_NULL;
+ }
+
+ /* Anything else, act as if LOGGER_DEFAULT */
+
+ /* generically we only expect these two values for write_to_log */
+ if ((write_to_log != __write_to_log_init) &&
+ (write_to_log != __write_to_log_daemon)) {
+ write_to_log = __write_to_log_init;
+ }
+
+ __android_log_unlock();
+
+ return LOGGER_DEFAULT;
+}
+
+LIBLOG_ABI_PUBLIC int android_get_log_frontend()
+{
+ int ret = LOGGER_DEFAULT;
+
+ __android_log_lock();
+ if (write_to_log == __write_to_log_null) {
+ ret = LOGGER_NULL;
+ } else if ((write_to_log != __write_to_log_init) &&
+ (write_to_log != __write_to_log_daemon)) {
+ ret = -EINVAL;
+ }
+ __android_log_unlock();
+
+ return ret;
+}