liblog: split out transports into separate files

Create config_logger, logger and logger_read to house the log
interfaces. Add fake_logger, logd_logger and pmsg_logger to
house the write and read transports. Allows for an easier and
direct path to add new transports to the library.

SideEffects: None, logger benchmark performance unaffected

Bug: 27176738
Bug: 27405083
Change-Id: I01b38637334a5242905c8c89f6ab0a92e2540008

1 files changed, 82 insertions, 0 deletions

diff --git a/liblog/logger_lock.c b/liblog/logger_lock.c
new file mode 100644
index 000000000..ee979bd5e
--- /dev/null
+++ b/liblog/logger_lock.c
@@ -0,0 +1,82 @@
+/*
+ * Copyright (C) 2007-2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/*
+ * Some OS specific dribs and drabs (locking etc).
+ */
+
+#if !defined(_WIN32)
+#include <pthread.h>
+#endif
+
+#include <private/android_filesystem_config.h>
+
+#include "logger.h"
+
+LIBLOG_HIDDEN uid_t __android_log_uid()
+{
+#if defined(_WIN32)
+    return AID_SYSTEM;
+#else
+    static uid_t last_uid = AID_ROOT; /* logd *always* starts up as AID_ROOT */
+
+    if (last_uid == AID_ROOT) { /* have we called to get the UID yet? */
+        last_uid = getuid();
+    }
+    return last_uid;
+#endif
+}
+
+LIBLOG_HIDDEN pid_t __android_log_pid()
+{
+    static pid_t last_pid = (pid_t) -1;
+
+    if (last_pid == (pid_t) -1) {
+        last_pid = getpid();
+    }
+    return last_pid;
+}
+
+#if !defined(_WIN32)
+static pthread_mutex_t log_init_lock = PTHREAD_MUTEX_INITIALIZER;
+#endif
+
+LIBLOG_HIDDEN void __android_log_lock()
+{
+#if !defined(_WIN32)
+    /*
+     * If we trigger a signal handler in the middle of locked activity and the
+     * signal handler logs a message, we could get into a deadlock state.
+     */
+    pthread_mutex_lock(&log_init_lock);
+#endif
+}
+
+LIBLOG_HIDDEN int __android_log_trylock()
+{
+#if !defined(_WIN32)
+    return pthread_mutex_trylock(&log_init_lock);
+#else
+    return 0;
+#endif
+}
+
+LIBLOG_HIDDEN void __android_log_unlock()
+{
+#if !defined(_WIN32)
+    pthread_mutex_unlock(&log_init_lock);
+#endif
+}