1 /*
2  * Copyright (C) 2020 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 #pragma once
18 
19 #include <sys/types.h>
20 
21 #include <functional>
22 
23 #include <log/log.h>
24 #include <log/log_read.h>
25 
26 #include "LogWriter.h"
27 
28 // A mask to represent which log buffers a reader is watching, values are (1 << LOG_ID_MAIN), etc.
29 using LogMask = uint32_t;
30 constexpr uint32_t kLogMaskAll = 0xFFFFFFFF;
31 
32 // State that a LogBuffer may want to persist across calls to FlushTo().
33 class FlushToState {
34   public:
FlushToState(uint64_t start,LogMask log_mask)35     FlushToState(uint64_t start, LogMask log_mask) : start_(start), log_mask_(log_mask) {}
~FlushToState()36     virtual ~FlushToState() {}
37 
start()38     uint64_t start() const { return start_; }
set_start(uint64_t start)39     void set_start(uint64_t start) { start_ = start; }
40 
log_mask()41     LogMask log_mask() const { return log_mask_; }
42 
43   private:
44     uint64_t start_;
45     LogMask log_mask_;
46 };
47 
48 // Enum for the return values of the `filter` function passed to FlushTo().
49 enum class FilterResult {
50     kSkip,
51     kStop,
52     kWrite,
53 };
54 
55 class LogBuffer {
56   public:
~LogBuffer()57     virtual ~LogBuffer() {}
58 
59     virtual void Init() = 0;
60 
61     virtual int Log(log_id_t log_id, log_time realtime, uid_t uid, pid_t pid, pid_t tid,
62                     const char* msg, uint16_t len) = 0;
63 
64     virtual std::unique_ptr<FlushToState> CreateFlushToState(uint64_t start, LogMask log_mask) = 0;
65     virtual bool FlushTo(
66             LogWriter* writer, FlushToState& state,
67             const std::function<FilterResult(log_id_t log_id, pid_t pid, uint64_t sequence,
68                                              log_time realtime)>& filter) = 0;
69 
70     virtual bool Clear(log_id_t id, uid_t uid) = 0;
71     virtual unsigned long GetSize(log_id_t id) = 0;
72     virtual int SetSize(log_id_t id, unsigned long size) = 0;
73 
74     virtual uint64_t sequence() const = 0;
75 };
76