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 #include "SerializedLogChunk.h"
18
19 #include <android-base/logging.h>
20
21 #include "CompressionEngine.h"
22
~SerializedLogChunk()23 SerializedLogChunk::~SerializedLogChunk() {
24 CHECK_EQ(reader_ref_count_, 0U);
25 }
26
Compress()27 void SerializedLogChunk::Compress() {
28 if (compressed_log_.size() == 0) {
29 CompressionEngine::GetInstance().Compress(contents_, write_offset_, compressed_log_);
30 LOG(INFO) << "Compressed Log, buffer max size: " << contents_.size()
31 << " size used: " << write_offset_
32 << " compressed size: " << compressed_log_.size();
33 }
34 }
35
36 // TODO: Develop a better reference counting strategy to guard against the case where the writer is
37 // much faster than the reader, and we needlessly compess / decompress the logs.
IncReaderRefCount()38 void SerializedLogChunk::IncReaderRefCount() {
39 if (++reader_ref_count_ != 1 || writer_active_) {
40 return;
41 }
42 contents_.Resize(write_offset_);
43 CompressionEngine::GetInstance().Decompress(compressed_log_, contents_);
44 }
45
DecReaderRefCount()46 void SerializedLogChunk::DecReaderRefCount() {
47 CHECK_NE(reader_ref_count_, 0U);
48 if (--reader_ref_count_ != 0) {
49 return;
50 }
51 if (!writer_active_) {
52 contents_.Resize(0);
53 }
54 }
55
ClearUidLogs(uid_t uid,log_id_t log_id,LogStatistics * stats)56 bool SerializedLogChunk::ClearUidLogs(uid_t uid, log_id_t log_id, LogStatistics* stats) {
57 CHECK_EQ(reader_ref_count_, 0U);
58 if (write_offset_ == 0) {
59 return true;
60 }
61
62 IncReaderRefCount();
63
64 int read_offset = 0;
65 int new_write_offset = 0;
66 while (read_offset < write_offset_) {
67 const auto* entry = log_entry(read_offset);
68 if (entry->uid() == uid) {
69 read_offset += entry->total_len();
70 if (stats != nullptr) {
71 stats->Subtract(entry->ToLogStatisticsElement(log_id));
72 }
73 continue;
74 }
75 size_t entry_total_len = entry->total_len();
76 if (read_offset != new_write_offset) {
77 memmove(contents_.data() + new_write_offset, contents_.data() + read_offset,
78 entry_total_len);
79 }
80 read_offset += entry_total_len;
81 new_write_offset += entry_total_len;
82 }
83
84 if (new_write_offset == 0) {
85 DecReaderRefCount();
86 return true;
87 }
88
89 // Clear the old compressed logs and set write_offset_ appropriately to compress the new
90 // partially cleared log.
91 if (new_write_offset != write_offset_) {
92 compressed_log_.Resize(0);
93 write_offset_ = new_write_offset;
94 Compress();
95 }
96
97 DecReaderRefCount();
98
99 return false;
100 }
101
CanLog(size_t len)102 bool SerializedLogChunk::CanLog(size_t len) {
103 return write_offset_ + len <= contents_.size();
104 }
105
Log(uint64_t sequence,log_time realtime,uid_t uid,pid_t pid,pid_t tid,const char * msg,uint16_t len)106 SerializedLogEntry* SerializedLogChunk::Log(uint64_t sequence, log_time realtime, uid_t uid,
107 pid_t pid, pid_t tid, const char* msg, uint16_t len) {
108 auto new_log_address = contents_.data() + write_offset_;
109 auto* entry = new (new_log_address) SerializedLogEntry(uid, pid, tid, sequence, realtime, len);
110 memcpy(entry->msg(), msg, len);
111 write_offset_ += entry->total_len();
112 highest_sequence_number_ = sequence;
113 return entry;
114 }