Tom Cherry | a687242 | 2020-04-17 13:05:11 -0700 | [diff] [blame] | 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 <inttypes.h> |
| 20 | |
| 21 | #include <android-base/logging.h> |
| 22 | #include <android-base/stringprintf.h> |
| 23 | |
| 24 | #define LOGGER_ENTRY_MAX_PAYLOAD 4068 // This constant is not in the NDK. |
| 25 | |
| 26 | namespace android { |
| 27 | namespace base { |
| 28 | |
| 29 | // This splits the message up line by line, by calling log_function with a pointer to the start of |
| 30 | // each line and the size up to the newline character. It sends size = -1 for the final line. |
| 31 | template <typename F, typename... Args> |
| 32 | static void SplitByLines(const char* msg, const F& log_function, Args&&... args) { |
| 33 | const char* newline = strchr(msg, '\n'); |
| 34 | while (newline != nullptr) { |
| 35 | log_function(msg, newline - msg, args...); |
| 36 | msg = newline + 1; |
| 37 | newline = strchr(msg, '\n'); |
| 38 | } |
| 39 | |
| 40 | log_function(msg, -1, args...); |
| 41 | } |
| 42 | |
| 43 | // This splits the message up into chunks that logs can process delimited by new lines. It calls |
| 44 | // log_function with the exact null terminated message that should be sent to logd. |
| 45 | // Note, despite the loops and snprintf's, if severity is not fatal and there are no new lines, |
| 46 | // this function simply calls log_function with msg without any extra overhead. |
| 47 | template <typename F> |
| 48 | static void SplitByLogdChunks(LogId log_id, LogSeverity severity, const char* tag, const char* file, |
| 49 | unsigned int line, const char* msg, const F& log_function) { |
| 50 | // The maximum size of a payload, after the log header that logd will accept is |
| 51 | // LOGGER_ENTRY_MAX_PAYLOAD, so subtract the other elements in the payload to find the size of |
| 52 | // the string that we can log in each pass. |
| 53 | // The protocol is documented in liblog/README.protocol.md. |
| 54 | // Specifically we subtract a byte for the priority, the length of the tag + its null terminator, |
| 55 | // and an additional byte for the null terminator on the payload. We subtract an additional 32 |
| 56 | // bytes for slack, similar to java/android/util/Log.java. |
| 57 | ptrdiff_t max_size = LOGGER_ENTRY_MAX_PAYLOAD - strlen(tag) - 35; |
| 58 | if (max_size <= 0) { |
| 59 | abort(); |
| 60 | } |
| 61 | // If we're logging a fatal message, we'll append the file and line numbers. |
| 62 | bool add_file = file != nullptr && (severity == FATAL || severity == FATAL_WITHOUT_ABORT); |
| 63 | |
| 64 | std::string file_header; |
| 65 | if (add_file) { |
| 66 | file_header = StringPrintf("%s:%u] ", file, line); |
| 67 | } |
| 68 | int file_header_size = file_header.size(); |
| 69 | |
| 70 | __attribute__((uninitialized)) char logd_chunk[max_size + 1]; |
| 71 | ptrdiff_t chunk_position = 0; |
| 72 | |
| 73 | auto call_log_function = [&]() { |
| 74 | log_function(log_id, severity, tag, logd_chunk); |
| 75 | chunk_position = 0; |
| 76 | }; |
| 77 | |
| 78 | auto write_to_logd_chunk = [&](const char* message, int length) { |
| 79 | int size_written = 0; |
| 80 | const char* new_line = chunk_position > 0 ? "\n" : ""; |
| 81 | if (add_file) { |
| 82 | size_written = snprintf(logd_chunk + chunk_position, sizeof(logd_chunk) - chunk_position, |
| 83 | "%s%s%.*s", new_line, file_header.c_str(), length, message); |
| 84 | } else { |
| 85 | size_written = snprintf(logd_chunk + chunk_position, sizeof(logd_chunk) - chunk_position, |
| 86 | "%s%.*s", new_line, length, message); |
| 87 | } |
| 88 | |
| 89 | // This should never fail, if it does and we set size_written to 0, which will skip this line |
| 90 | // and move to the next one. |
| 91 | if (size_written < 0) { |
| 92 | size_written = 0; |
| 93 | } |
| 94 | chunk_position += size_written; |
| 95 | }; |
| 96 | |
| 97 | const char* newline = strchr(msg, '\n'); |
| 98 | while (newline != nullptr) { |
| 99 | // If we have data in the buffer and this next line doesn't fit, write the buffer. |
| 100 | if (chunk_position != 0 && chunk_position + (newline - msg) + 1 + file_header_size > max_size) { |
| 101 | call_log_function(); |
| 102 | } |
| 103 | |
| 104 | // Otherwise, either the next line fits or we have any empty buffer and too large of a line to |
| 105 | // ever fit, in both cases, we add it to the buffer and continue. |
| 106 | write_to_logd_chunk(msg, newline - msg); |
| 107 | |
| 108 | msg = newline + 1; |
| 109 | newline = strchr(msg, '\n'); |
| 110 | } |
| 111 | |
| 112 | // If we have left over data in the buffer and we can fit the rest of msg, add it to the buffer |
| 113 | // then write the buffer. |
| 114 | if (chunk_position != 0 && |
| 115 | chunk_position + static_cast<int>(strlen(msg)) + 1 + file_header_size <= max_size) { |
| 116 | write_to_logd_chunk(msg, -1); |
| 117 | call_log_function(); |
| 118 | } else { |
| 119 | // If the buffer is not empty and we can't fit the rest of msg into it, write its contents. |
| 120 | if (chunk_position != 0) { |
| 121 | call_log_function(); |
| 122 | } |
| 123 | // Then write the rest of the msg. |
| 124 | if (add_file) { |
| 125 | snprintf(logd_chunk, sizeof(logd_chunk), "%s%s", file_header.c_str(), msg); |
| 126 | log_function(log_id, severity, tag, logd_chunk); |
| 127 | } else { |
| 128 | log_function(log_id, severity, tag, msg); |
| 129 | } |
| 130 | } |
| 131 | } |
| 132 | |
| 133 | static std::pair<int, int> CountSizeAndNewLines(const char* message) { |
| 134 | int size = 0; |
| 135 | int new_lines = 0; |
| 136 | while (*message != '\0') { |
| 137 | size++; |
| 138 | if (*message == '\n') { |
| 139 | ++new_lines; |
| 140 | } |
| 141 | ++message; |
| 142 | } |
| 143 | return {size, new_lines}; |
| 144 | } |
| 145 | |
| 146 | // This adds the log header to each line of message and returns it as a string intended to be |
| 147 | // written to stderr. |
| 148 | static std::string StderrOutputGenerator(const struct tm& now, int pid, uint64_t tid, |
| 149 | LogSeverity severity, const char* tag, const char* file, |
| 150 | unsigned int line, const char* message) { |
| 151 | char timestamp[32]; |
| 152 | strftime(timestamp, sizeof(timestamp), "%m-%d %H:%M:%S", &now); |
| 153 | |
| 154 | static const char log_characters[] = "VDIWEFF"; |
| 155 | static_assert(arraysize(log_characters) - 1 == FATAL + 1, |
| 156 | "Mismatch in size of log_characters and values in LogSeverity"); |
| 157 | char severity_char = log_characters[severity]; |
| 158 | std::string line_prefix; |
| 159 | if (file != nullptr) { |
| 160 | line_prefix = StringPrintf("%s %c %s %5d %5" PRIu64 " %s:%u] ", tag ? tag : "nullptr", |
| 161 | severity_char, timestamp, pid, tid, file, line); |
| 162 | } else { |
| 163 | line_prefix = StringPrintf("%s %c %s %5d %5" PRIu64 " ", tag ? tag : "nullptr", severity_char, |
| 164 | timestamp, pid, tid); |
| 165 | } |
| 166 | |
| 167 | auto [size, new_lines] = CountSizeAndNewLines(message); |
| 168 | std::string output_string; |
| 169 | output_string.reserve(size + new_lines * line_prefix.size() + 1); |
| 170 | |
| 171 | auto concat_lines = [&](const char* message, int size) { |
| 172 | output_string.append(line_prefix); |
| 173 | if (size == -1) { |
| 174 | output_string.append(message); |
| 175 | } else { |
| 176 | output_string.append(message, size); |
| 177 | } |
| 178 | output_string.append("\n"); |
| 179 | }; |
| 180 | SplitByLines(message, concat_lines); |
| 181 | return output_string; |
| 182 | } |
| 183 | |
| 184 | } // namespace base |
| 185 | } // namespace android |