58ba58a97c
C (but not C++) has a concept of a flexible array member, which is documented at https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html . Using a flexible array member indicates that the structure is really a header for a variable length object. In logd's case, the variable length structure android_event_string_t was embedded within another structure called android_log_event_string_t. This makes gcc's __builtin_object_size() function really confused. When compiling with C++, __builtin_object_size(android_log_event_string_t.payload.data, 1) would return 0, whereas if you compiled the code with C, the same call would (properly) return -1. Code which does automatic bounds checking, such as the proposed patch at https://android-review.googlesource.com/145411 , will cause problems for logd if this syntax is used. Don't try to embed a variable length structure within another structure. This doesn't appear to be valid C nor C++, and while it's worked, it seems problematic. Instead, inline the structure so it's one big happy structure. Change-Id: I8ac02b7142a4f6560f5f80df2effcf720f9896fc
98 lines
3 KiB
C
98 lines
3 KiB
C
/*
|
|
* Copyright (C) 2015 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.
|
|
*/
|
|
|
|
/* This file is used to define the internal protocol for the Android Logger */
|
|
|
|
#ifndef _SYSTEM_CORE_INCLUDE_PRIVATE_ANDROID_LOGGER_H_
|
|
#define _SYSTEM_CORE_INCLUDE_PRIVATE_ANDROID_LOGGER_H_
|
|
|
|
#include <stdint.h>
|
|
|
|
#include <log/log.h>
|
|
#include <log/log_read.h>
|
|
|
|
#define LOGGER_MAGIC 'l'
|
|
|
|
/* Header Structure to pstore */
|
|
typedef struct __attribute__((__packed__)) {
|
|
uint8_t magic;
|
|
uint16_t len;
|
|
uint16_t uid;
|
|
uint16_t pid;
|
|
} android_pmsg_log_header_t;
|
|
|
|
/* Header Structure to logd, and second header for pstore */
|
|
typedef struct __attribute__((__packed__)) {
|
|
typeof_log_id_t id;
|
|
uint16_t tid;
|
|
log_time realtime;
|
|
} android_log_header_t;
|
|
|
|
/* Event Header Structure to logd */
|
|
typedef struct __attribute__((__packed__)) {
|
|
int32_t tag; // Little Endian Order
|
|
} android_event_header_t;
|
|
|
|
/* Event payload EVENT_TYPE_INT */
|
|
typedef struct __attribute__((__packed__)) {
|
|
int8_t type; // EVENT_TYPE_INT
|
|
int32_t data; // Little Endian Order
|
|
} android_event_int_t;
|
|
|
|
/* Event with single EVENT_TYPE_INT */
|
|
typedef struct __attribute__((__packed__)) {
|
|
android_event_header_t header;
|
|
android_event_int_t payload;
|
|
} android_log_event_int_t;
|
|
|
|
/* Event payload EVENT_TYPE_LONG */
|
|
typedef struct __attribute__((__packed__)) {
|
|
int8_t type; // EVENT_TYPE_LONG
|
|
int64_t data; // Little Endian Order
|
|
} android_event_long_t;
|
|
|
|
/* Event with single EVENT_TYPE_LONG */
|
|
typedef struct __attribute__((__packed__)) {
|
|
android_event_header_t header;
|
|
android_event_long_t payload;
|
|
} android_log_event_long_t;
|
|
|
|
/*
|
|
* Event payload EVENT_TYPE_STRING
|
|
*
|
|
* Danger: do not embed this structure into another structure.
|
|
* This structure uses a flexible array member, and when
|
|
* compiled using g++, __builtin_object_size(data, 1) returns
|
|
* a bad value. This is possibly a g++ bug, or a bug due to
|
|
* the fact that flexible array members are not supported
|
|
* in C++.
|
|
* http://stackoverflow.com/questions/4412749/are-flexible-array-members-valid-in-c
|
|
*/
|
|
typedef struct __attribute__((__packed__)) {
|
|
int8_t type; // EVENT_TYPE_STRING;
|
|
int32_t length; // Little Endian Order
|
|
char data[];
|
|
} android_event_string_t;
|
|
|
|
/* Event with single EVENT_TYPE_STRING */
|
|
typedef struct __attribute__((__packed__)) {
|
|
android_event_header_t header;
|
|
int8_t type; // EVENT_TYPE_STRING;
|
|
int32_t length; // Little Endian Order
|
|
char data[];
|
|
} android_log_event_string_t;
|
|
|
|
#endif
|