61910f123f
These historically used atomics to manage their lifetime. They were
unfortunately unsafe and later replace with a RwLock. A lock is
also problematic as it is too heavy weight for the typical use case
and implies that logging is neither async nor fork safe.
This change returns us to using atomics with two key changes:
1) compare_exchange_strong() is used instead of atomic_exchange().
The latter has a race condition where a separate thread could have
read the atomic value into a register, while the thread performing
the atomic_exchange closes that FD. The new code only changes the
FD in the atomic if it is uninitialized.
2) Using the fact that DGRAM sockets can have connect() called on them
multiple times, it uses a single logd_socket for the duration of
the program.
These sockets are thread/async/fork safely created and accessed.
The one caveat is __android_log_close(), which is intended only to be
used by zygote when it is single threaded and is therefore not thread
safe. It will close this socket and reset the underlying variable,
such that the next log message will go through the above
initialization.
Bug: 65062446
Test: logging works, logging unit tests
Test: new unit test
Merged-In: Ia4dbf7479dbe50683d124558ab2f83bff53b8f5f
Change-Id: Ia4dbf7479dbe50683d124558ab2f83bff53b8f5f
(cherry picked from commit 7acfba274c)
156 lines
4.7 KiB
C
156 lines
4.7 KiB
C
/*
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* Copyright (C) 2005-2014 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#pragma once
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/* Too many in the ecosystem assume these are included */
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#if !defined(_WIN32)
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#include <pthread.h>
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#endif
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#include <stdint.h> /* uint16_t, int32_t */
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#include <stdio.h>
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#include <time.h>
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#include <unistd.h>
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#include <android/log.h>
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#include <log/log_id.h>
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#include <log/log_main.h>
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#include <log/log_radio.h>
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#include <log/log_read.h>
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#include <log/log_safetynet.h>
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#include <log/log_system.h>
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#include <log/log_time.h>
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#ifdef __cplusplus
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extern "C" {
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#endif
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/*
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* LOG_TAG is the local tag used for the following simplified
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* logging macros. You can change this preprocessor definition
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* before using the other macros to change the tag.
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*/
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#ifndef LOG_TAG
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#define LOG_TAG NULL
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#endif
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/*
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* Normally we strip the effects of ALOGV (VERBOSE messages),
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* LOG_FATAL and LOG_FATAL_IF (FATAL assert messages) from the
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* release builds be defining NDEBUG. You can modify this (for
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* example with "#define LOG_NDEBUG 0" at the top of your source
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* file) to change that behavior.
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*/
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#ifndef LOG_NDEBUG
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#ifdef NDEBUG
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#define LOG_NDEBUG 1
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#else
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#define LOG_NDEBUG 0
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#endif
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#endif
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/*
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* Event logging.
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*/
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/*
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* The following should not be used directly.
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*/
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int __android_log_bwrite(int32_t tag, const void* payload, size_t len);
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int __android_log_btwrite(int32_t tag, char type, const void* payload,
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size_t len);
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int __android_log_bswrite(int32_t tag, const char* payload);
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int __android_log_stats_bwrite(int32_t tag, const void* payload, size_t len);
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#define android_bWriteLog(tag, payload, len) \
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__android_log_bwrite(tag, payload, len)
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#define android_btWriteLog(tag, type, payload, len) \
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__android_log_btwrite(tag, type, payload, len)
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/*
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* Event log entry types.
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*/
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#ifndef __AndroidEventLogType_defined
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#define __AndroidEventLogType_defined
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typedef enum {
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/* Special markers for android_log_list_element type */
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EVENT_TYPE_LIST_STOP = '\n', /* declare end of list */
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EVENT_TYPE_UNKNOWN = '?', /* protocol error */
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/* must match with declaration in java/android/android/util/EventLog.java */
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EVENT_TYPE_INT = 0, /* int32_t */
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EVENT_TYPE_LONG = 1, /* int64_t */
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EVENT_TYPE_STRING = 2,
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EVENT_TYPE_LIST = 3,
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EVENT_TYPE_FLOAT = 4,
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} AndroidEventLogType;
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#endif
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#define sizeof_AndroidEventLogType sizeof(typeof_AndroidEventLogType)
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#define typeof_AndroidEventLogType unsigned char
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#ifndef LOG_EVENT_INT
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#define LOG_EVENT_INT(_tag, _value) \
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{ \
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int intBuf = _value; \
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(void)android_btWriteLog(_tag, EVENT_TYPE_INT, &intBuf, sizeof(intBuf)); \
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}
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#endif
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#ifndef LOG_EVENT_LONG
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#define LOG_EVENT_LONG(_tag, _value) \
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{ \
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long long longBuf = _value; \
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(void)android_btWriteLog(_tag, EVENT_TYPE_LONG, &longBuf, sizeof(longBuf)); \
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}
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#endif
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#ifndef LOG_EVENT_FLOAT
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#define LOG_EVENT_FLOAT(_tag, _value) \
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{ \
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float floatBuf = _value; \
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(void)android_btWriteLog(_tag, EVENT_TYPE_FLOAT, &floatBuf, \
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sizeof(floatBuf)); \
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}
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#endif
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#ifndef LOG_EVENT_STRING
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#define LOG_EVENT_STRING(_tag, _value) \
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(void)__android_log_bswrite(_tag, _value);
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#endif
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#ifdef __linux__
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clockid_t android_log_clockid(void);
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#endif /* __linux__ */
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/* --------------------------------------------------------------------- */
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/*
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* Release any logger resources (a new log write will immediately re-acquire)
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*
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* This is specifically meant to be used by Zygote to close open file descriptors after fork()
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* and before specialization. O_CLOEXEC is used on file descriptors, so they will be closed upon
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* exec() in normal use cases.
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*
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* Note that this is not safe to call from a multi-threaded program.
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*/
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void __android_log_close(void);
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#ifdef __cplusplus
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}
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#endif
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