1 /*
2 * Copyright (C) 2016 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 "event_log_list_builder.h"
18
19 #include <cinttypes>
20 #include <memory>
21 #include <string>
22 #include <android-base/logging.h>
23 #include <log/log.h>
24
25 namespace {
26
27 const size_t MAX_EVENT_PAYLOAD_SIZE = 512 - 1; // Leave room for final '\n'.
28 const size_t EVENT_TYPE_SIZE = 1; // Size in bytes of the event type marker.
29
30 } // namespace
31
EventLogListBuilder()32 EventLogListBuilder::EventLogListBuilder()
33 : payload_count_(0),
34 payload_size_(0),
35 payload_(std::make_unique<uint8_t[]>(MAX_EVENT_PAYLOAD_SIZE)) {
36 memset(payload_.get(), 0, MAX_EVENT_PAYLOAD_SIZE);
37
38 // Set up the top-level EventLog data type.
39 AppendByte(EVENT_TYPE_LIST);
40
41 // Skip over the byte prepresenting the number of items in the list. This
42 // value is set in Release().
43 payload_size_++;
44 }
45
Append(int value)46 bool EventLogListBuilder::Append(int value) {
47 DCHECK_NE(static_cast<uint8_t*>(nullptr), payload_.get());
48
49 if (!IsSpaceAvailable(sizeof(value) + EVENT_TYPE_SIZE)) {
50 return false;
51 }
52
53 AppendByte(EVENT_TYPE_INT);
54 AppendData(&value, sizeof(value));
55
56 payload_count_++;
57 return true;
58 }
59
Append(const std::string & value)60 bool EventLogListBuilder::Append(const std::string& value) {
61 DCHECK_NE(static_cast<uint8_t*>(nullptr), payload_.get());
62
63 int len = value.length();
64 if (!IsSpaceAvailable(sizeof(len) + len)) {
65 return false;
66 }
67
68 AppendByte(EVENT_TYPE_STRING);
69 AppendData(&len, sizeof(len));
70 AppendData(value.c_str(), len);
71
72 payload_count_++;
73 return true;
74 }
75
Release(std::unique_ptr<uint8_t[]> * log,size_t * size)76 void EventLogListBuilder::Release(std::unique_ptr<uint8_t[]>* log,
77 size_t* size) {
78 // Finalize the log payload.
79 payload_[1] = payload_count_;
80
81 // Return the log payload.
82 *size = payload_size_;
83 *log = std::move(payload_);
84 }
85
AppendData(const void * data,size_t size)86 void EventLogListBuilder::AppendData(const void* data, size_t size) {
87 DCHECK_LT(payload_size_ + size, MAX_EVENT_PAYLOAD_SIZE);
88 memcpy(&payload_[payload_size_], data, size);
89 payload_size_ += size;
90 }
91
AppendByte(uint8_t byte)92 void EventLogListBuilder::AppendByte(uint8_t byte) {
93 DCHECK_LT(payload_size_ + sizeof(byte), MAX_EVENT_PAYLOAD_SIZE);
94 payload_[payload_size_++] = byte;
95 }
96
IsSpaceAvailable(size_t value_size)97 bool EventLogListBuilder::IsSpaceAvailable(size_t value_size) {
98 size_t space_needed = value_size + EVENT_TYPE_SIZE;
99 if (payload_size_ + space_needed > MAX_EVENT_PAYLOAD_SIZE) {
100 size_t remaining = MAX_EVENT_PAYLOAD_SIZE - payload_size_;
101 LOG(WARNING) << "Not enough space for value. remain=" <<
102 remaining << "; needed=" << space_needed;
103 return false;
104 }
105
106 return true;
107 }
108