liblog: have writers handle their own state

Remove the transport available and open functions since the writers
are able to manage their own state.  Remove the initialization dance
with write_to_log, since it is unneeded once this is removed as well.

Remove the global lock around the close() functions as correct locking
has been added to the writers in a previous change.

Test: logging works, liblog-unit-tests
Change-Id: If7fa11e773763d0b5fcb2e696ad1c88ff4a4cfdf

liblog/Android.bp

@@ -17,7 +17,6 @@
 liblog_sources = [
     "log_event_list.cpp",
     "log_event_write.cpp",
-    "logger_lock.cpp",
     "logger_name.cpp",
     "logger_read.cpp",
     "logger_write.cpp",

liblog/fake_log_device.cpp

@@ -52,10 +52,6 @@ static void FakeClose();
 static int FakeWrite(log_id_t log_id, struct timespec* ts, struct iovec* vec, size_t nr);
 
 struct android_log_transport_write fakeLoggerWrite = {
-    .name = "fake",
-    .logMask = 0,
-    .available = [](log_id_t) { return 0; },
-    .open = [] { return 0; },
     .close = FakeClose,
     .write = FakeWrite,
 };

liblog/logd_writer.cpp

@@ -45,10 +45,6 @@ static int LogdWrite(log_id_t logId, struct timespec* ts, struct iovec* vec, siz
 static void LogdClose();
 
 struct android_log_transport_write logdLoggerWrite = {
-    .name = "logd",
-    .logMask = 0,
-    .available = [](log_id_t) { return 0; },
-    .open = [] { return 0; },
     .close = LogdClose,
     .write = LogdWrite,
 };

liblog/logger.h

@@ -26,20 +26,7 @@
 
 __BEGIN_DECLS
 
-/* Union, sock or fd of zero is not allowed unless static initialized */
-union android_log_context_union {
-  void* priv;
-  atomic_int sock;
-  atomic_int fd;
-};
-
 struct android_log_transport_write {
-  const char* name;                  /* human name to describe the transport */
-  unsigned logMask;                  /* mask cache of available() success */
-  union android_log_context_union context; /* Initialized by static allocation */
-
-  int (*available)(log_id_t logId); /* Does not cause resources to be taken */
-  int (*open)();   /* can be called multiple times, reusing current resources */
   void (*close)(); /* free up resources */
   /* write log to transport, returns number of bytes propagated, or -errno */
   int (*write)(log_id_t logId, struct timespec* ts, struct iovec* vec,
@@ -83,8 +70,4 @@ static inline uid_t __android_log_uid() {
 }
 #endif
 
-void __android_log_lock();
-int __android_log_trylock();
-void __android_log_unlock();
-
 __END_DECLS

liblog/logger_lock.cpp

@@ -1,53 +0,0 @@
-/*
- * 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 "logger.h"
-
-#if !defined(_WIN32)
-static pthread_mutex_t log_init_lock = PTHREAD_MUTEX_INITIALIZER;
-#endif
-
-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
-}
-
-int __android_log_trylock() {
-#if !defined(_WIN32)
-  return pthread_mutex_trylock(&log_init_lock);
-#else
-  return 0;
-#endif
-}
-
-void __android_log_unlock() {
-#if !defined(_WIN32)
-  pthread_mutex_unlock(&log_init_lock);
-#endif
-}

liblog/logger_write.cpp

@@ -46,11 +46,8 @@ android_log_transport_write* android_log_write = &fakeLoggerWrite;
 android_log_transport_write* android_log_persist_write = nullptr;
 #endif
 
-static int __write_to_log_init(log_id_t, struct iovec* vec, size_t nr);
-static int (*write_to_log)(log_id_t, struct iovec* vec, size_t nr) = __write_to_log_init;
-
-static int check_log_uid_permissions() {
 #if defined(__ANDROID__)
+static int check_log_uid_permissions() {
   uid_t uid = __android_log_uid();
 
   /* Matches clientHasLogCredentials() in logd */
@@ -87,43 +84,14 @@ static int check_log_uid_permissions() {
       }
     }
   }
-#endif
   return 0;
 }
-
-static void __android_log_cache_available(struct android_log_transport_write* node) {
-  uint32_t i;
-
-  if (node->logMask) {
-    return;
-  }
-
-  for (i = LOG_ID_MIN; i < LOG_ID_MAX; ++i) {
-    if (i != LOG_ID_KERNEL && (i != LOG_ID_SECURITY || check_log_uid_permissions() == 0) &&
-        (*node->available)(static_cast<log_id_t>(i)) >= 0) {
-      node->logMask |= 1 << i;
-    }
-  }
-}
+#endif
 
 /*
  * Release any logger resources. A new log write will immediately re-acquire.
  */
 void __android_log_close() {
-  __android_log_lock();
-
-  write_to_log = __write_to_log_init;
-
-  /*
-   * Threads that are actively writing at this point are not held back
-   * by a lock and are at risk of dropping the messages with a return code
-   * -EBADF. Prefer to return error code than add the overhead of a lock to
-   * each log writing call to guarantee delivery. In addition, anyone
-   * calling this is doing so to release the logging resources and shut down,
-   * for them to do so with outstanding log requests in other threads is a
-   * disengenuous use of this function.
-   */
-
   if (android_log_write != nullptr) {
     android_log_write->close();
   }
@@ -132,44 +100,18 @@ void __android_log_close() {
     android_log_persist_write->close();
   }
 
-  __android_log_unlock();
 }
 
-static bool transport_initialize(android_log_transport_write* transport) {
-  if (transport == nullptr) {
-    return false;
-  }
-
-  __android_log_cache_available(transport);
-  if (!transport->logMask) {
-    return false;
-  }
-
-  // TODO: Do we actually need to call close() if open() fails?
-  if (transport->open() < 0) {
-    transport->close();
-    return false;
-  }
-
-  return true;
-}
-
-/* log_init_lock assumed */
-static int __write_to_log_initialize() {
-  if (!transport_initialize(android_log_write)) {
-    return -ENODEV;
-  }
-
-  transport_initialize(android_log_persist_write);
-
-  return 1;
-}
-
-static int __write_to_log_daemon(log_id_t log_id, struct iovec* vec, size_t nr) {
+static int write_to_log(log_id_t log_id, struct iovec* vec, size_t nr) {
   int ret, save_errno;
   struct timespec ts;
 
   save_errno = errno;
+
+  if (log_id == LOG_ID_KERNEL) {
+    return -EINVAL;
+  }
+
 #if defined(__ANDROID__)
   clock_gettime(android_log_clockid(), &ts);
 
@@ -215,9 +157,8 @@ static int __write_to_log_daemon(log_id_t log_id, struct iovec* vec, size_t nr)
 #endif
 
   ret = 0;
-  size_t i = 1 << log_id;
 
-  if (android_log_write != nullptr && (android_log_write->logMask & i)) {
+  if (android_log_write != nullptr) {
     ssize_t retval;
     retval = android_log_write->write(log_id, &ts, vec, nr);
     if (ret >= 0) {
@@ -225,7 +166,7 @@ static int __write_to_log_daemon(log_id_t log_id, struct iovec* vec, size_t nr)
     }
   }
 
-  if (android_log_persist_write != nullptr && (android_log_persist_write->logMask & i)) {
+  if (android_log_persist_write != nullptr) {
     android_log_persist_write->write(log_id, &ts, vec, nr);
   }
 
@@ -233,29 +174,6 @@ static int __write_to_log_daemon(log_id_t log_id, struct iovec* vec, size_t nr)
   return ret;
 }
 
-static int __write_to_log_init(log_id_t log_id, struct iovec* vec, size_t nr) {
-  int ret, save_errno = errno;
-
-  __android_log_lock();
-
-  if (write_to_log == __write_to_log_init) {
-    ret = __write_to_log_initialize();
-    if (ret < 0) {
-      __android_log_unlock();
-      errno = save_errno;
-      return ret;
-    }
-
-    write_to_log = __write_to_log_daemon;
-  }
-
-  __android_log_unlock();
-
-  ret = write_to_log(log_id, vec, nr);
-  errno = save_errno;
-  return ret;
-}
-
 int __android_log_write(int prio, const char* tag, const char* msg) {
   return __android_log_buf_write(LOG_ID_MAIN, prio, tag, msg);
 }

liblog/pmsg_writer.cpp

@@ -40,10 +40,6 @@ static void PmsgClose();
 static int PmsgWrite(log_id_t logId, struct timespec* ts, struct iovec* vec, size_t nr);
 
 struct android_log_transport_write pmsgLoggerWrite = {
-    .name = "pmsg",
-    .logMask = 0,
-    .available = [](log_id_t) { return 0; },
-    .open = [] { return 0; },
     .close = PmsgClose,
     .write = PmsgWrite,
 };