simpleperf/record_file_writer.cpp

/*
 * 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.
 */

#include "record_file.h"

#include <fcntl.h>
#include <string.h>
#include <sys/mman.h>
#include <unistd.h>
#include <set>
#include <string>
#include <unordered_map>
#include <vector>

#include <android-base/file.h>
#include <android-base/logging.h>

#include "event_attr.h"
#include "perf_event.h"
#include "record.h"
#include "utils.h"

using namespace PerfFileFormat;

std::unique_ptr<RecordFileWriter> RecordFileWriter::CreateInstance(const std::string& filename) {
  // Remove old perf.data to avoid file ownership problems.
  std::string err;
  if (!android::base::RemoveFileIfExists(filename, &err)) {
    LOG(ERROR) << "failed to remove file " << filename << ": " << err;
    return nullptr;
  }
  FILE* fp = fopen(filename.c_str(), "web+");
  if (fp == nullptr) {
    PLOG(ERROR) << "failed to open record file '" << filename << "'";
    return nullptr;
  }

  return std::unique_ptr<RecordFileWriter>(new RecordFileWriter(filename, fp));
}

RecordFileWriter::RecordFileWriter(const std::string& filename, FILE* fp)
    : filename_(filename),
      record_fp_(fp),
      attr_section_offset_(0),
      attr_section_size_(0),
      data_section_offset_(0),
      data_section_size_(0),
      feature_section_offset_(0),
      feature_count_(0) {
}

RecordFileWriter::~RecordFileWriter() {
  if (record_fp_ != nullptr) {
    Close();
  }
}

bool RecordFileWriter::WriteAttrSection(const std::vector<EventAttrWithId>& attr_ids) {
  if (attr_ids.empty()) {
    return false;
  }

  // Skip file header part.
  if (fseek(record_fp_, sizeof(FileHeader), SEEK_SET) == -1) {
    return false;
  }

  // Write id section.
  uint64_t id_section_offset;
  if (!GetFilePos(&id_section_offset)) {
    return false;
  }
  for (auto& attr_id : attr_ids) {
    if (!Write(attr_id.ids.data(), attr_id.ids.size() * sizeof(uint64_t))) {
      return false;
    }
  }

  // Write attr section.
  uint64_t attr_section_offset;
  if (!GetFilePos(&attr_section_offset)) {
    return false;
  }
  for (auto& attr_id : attr_ids) {
    FileAttr file_attr;
    file_attr.attr = *attr_id.attr;
    file_attr.ids.offset = id_section_offset;
    file_attr.ids.size = attr_id.ids.size() * sizeof(uint64_t);
    id_section_offset += file_attr.ids.size;
    if (!Write(&file_attr, sizeof(file_attr))) {
      return false;
    }
  }

  uint64_t data_section_offset;
  if (!GetFilePos(&data_section_offset)) {
    return false;
  }

  attr_section_offset_ = attr_section_offset;
  attr_section_size_ = data_section_offset - attr_section_offset;
  data_section_offset_ = data_section_offset;

  // Save event_attr for use when reading records.
  event_attr_ = *attr_ids[0].attr;
  return true;
}

bool RecordFileWriter::WriteRecord(const Record& record) {
  // linux-tools-perf only accepts records with size <= 65535 bytes. To make
  // perf.data generated by simpleperf be able to be parsed by linux-tools-perf,
  // Split simpleperf custom records which are > 65535 into a bunch of
  // RECORD_SPLIT records, followed by a RECORD_SPLIT_END record.
  constexpr uint32_t RECORD_SIZE_LIMIT = 65535;
  if (record.size() <= RECORD_SIZE_LIMIT) {
    WriteData(record.Binary(), record.size());
    return true;
  }
  CHECK_GT(record.type(), SIMPLE_PERF_RECORD_TYPE_START);
  const char* p = record.Binary();
  uint32_t left_bytes = static_cast<uint32_t>(record.size());
  RecordHeader header;
  header.type = SIMPLE_PERF_RECORD_SPLIT;
  char header_buf[Record::header_size()];
  char* header_p;
  while (left_bytes > 0) {
    uint32_t bytes_to_write = std::min(RECORD_SIZE_LIMIT - Record::header_size(), left_bytes);
    header.size = bytes_to_write + Record::header_size();
    header_p = header_buf;
    header.MoveToBinaryFormat(header_p);
    if (!WriteData(header_buf, Record::header_size())) {
      return false;
    }
    if (!WriteData(p, bytes_to_write)) {
      return false;
    }
    p += bytes_to_write;
    left_bytes -= bytes_to_write;
  }
  header.type = SIMPLE_PERF_RECORD_SPLIT_END;
  header.size = Record::header_size();
  header_p = header_buf;
  header.MoveToBinaryFormat(header_p);
  return WriteData(header_buf, Record::header_size());
}

bool RecordFileWriter::WriteData(const void* buf, size_t len) {
  if (!Write(buf, len)) {
    return false;
  }
  data_section_size_ += len;
  return true;
}

bool RecordFileWriter::Write(const void* buf, size_t len) {
  if (fwrite(buf, len, 1, record_fp_) != 1) {
    PLOG(ERROR) << "failed to write to record file '" << filename_ << "'";
    return false;
  }
  return true;
}

bool RecordFileWriter::Read(void* buf, size_t len) {
  if (len != 0u && fread(buf, len, 1, record_fp_) != 1) {
    PLOG(ERROR) << "failed to read record file '" << filename_ << "'";
    return false;
  }
  return true;
}

bool RecordFileWriter::ReadDataSection(const std::function<void(const Record*)>& callback) {
  if (fseek(record_fp_, data_section_offset_, SEEK_SET) == -1) {
    PLOG(ERROR) << "fseek() failed";
    return false;
  }
  std::vector<char> record_buf(512);
  uint64_t read_pos = 0;
  while (read_pos < data_section_size_) {
    if (!Read(record_buf.data(), Record::header_size())) {
      return false;
    }
    RecordHeader header(record_buf.data());
    if (record_buf.size() < header.size) {
      record_buf.resize(header.size);
    }
    if (!Read(record_buf.data() + Record::header_size(), header.size - Record::header_size())) {
      return false;
    }
    read_pos += header.size;
    std::unique_ptr<Record> r = ReadRecordFromBuffer(event_attr_, header.type, record_buf.data());
    callback(r.get());
  }
  return true;
}

bool RecordFileWriter::GetFilePos(uint64_t* file_pos) {
  off_t offset = ftello(record_fp_);
  if (offset == -1) {
    PLOG(ERROR) << "ftello() failed";
    return false;
  }
  *file_pos = static_cast<uint64_t>(offset);
  return true;
}

bool RecordFileWriter::BeginWriteFeatures(size_t feature_count) {
  feature_section_offset_ = data_section_offset_ + data_section_size_;
  feature_count_ = feature_count;
  uint64_t feature_header_size = feature_count * sizeof(SectionDesc);

  // Reserve enough space in the record file for the feature header.
  std::vector<unsigned char> zero_data(feature_header_size);
  if (fseek(record_fp_, feature_section_offset_, SEEK_SET) == -1) {
    PLOG(ERROR) << "fseek() failed";
    return false;
  }
  return Write(zero_data.data(), zero_data.size());
}

bool RecordFileWriter::WriteBuildIdFeature(const std::vector<BuildIdRecord>& build_id_records) {
  if (!WriteFeatureBegin(FEAT_BUILD_ID)) {
    return false;
  }
  for (auto& record : build_id_records) {
    if (!Write(record.Binary(), record.size())) {
      return false;
    }
  }
  return WriteFeatureEnd(FEAT_BUILD_ID);
}

bool RecordFileWriter::WriteStringWithLength(const std::string& s) {
  uint32_t len = static_cast<uint32_t>(Align(s.size() + 1, 64));
  if (!Write(&len, sizeof(len))) {
    return false;
  }
  if (!Write(&s[0], s.size() + 1)) {
    return false;
  }
  size_t pad_size = Align(s.size() + 1, 64) - s.size() - 1;
  if (pad_size > 0u) {
    char align_buf[pad_size];
    memset(align_buf, '\0', pad_size);
    if (!Write(align_buf, pad_size)) {
      return false;
    }
  }
  return true;
}

bool RecordFileWriter::WriteFeatureString(int feature, const std::string& s) {
  if (!WriteFeatureBegin(feature)) {
    return false;
  }
  if (!WriteStringWithLength(s)) {
    return false;
  }
  return WriteFeatureEnd(feature);
}

bool RecordFileWriter::WriteCmdlineFeature(const std::vector<std::string>& cmdline) {
  if (!WriteFeatureBegin(FEAT_CMDLINE)) {
    return false;
  }
  uint32_t arg_count = cmdline.size();
  if (!Write(&arg_count, sizeof(arg_count))) {
    return false;
  }
  for (auto& arg : cmdline) {
    if (!WriteStringWithLength(arg)) {
      return false;
    }
  }
  return WriteFeatureEnd(FEAT_CMDLINE);
}

bool RecordFileWriter::WriteBranchStackFeature() {
  if (!WriteFeatureBegin(FEAT_BRANCH_STACK)) {
    return false;
  }
  return WriteFeatureEnd(FEAT_BRANCH_STACK);
}

bool RecordFileWriter::WriteFileFeature(const std::string& file_path,
                                        uint32_t file_type,
                                        uint64_t min_vaddr,
                                        const std::vector<const Symbol*>& symbols) {
  uint32_t size = file_path.size() + 1 + sizeof(uint32_t) * 2 +
      sizeof(uint64_t) + symbols.size() * (sizeof(uint64_t) + sizeof(uint32_t));
  for (const auto& symbol : symbols) {
    size += strlen(symbol->Name()) + 1;
  }
  std::vector<char> buf(sizeof(uint32_t) + size);
  char* p = buf.data();
  MoveToBinaryFormat(size, p);
  MoveToBinaryFormat(file_path.c_str(), file_path.size() + 1, p);
  MoveToBinaryFormat(file_type, p);
  MoveToBinaryFormat(min_vaddr, p);
  uint32_t symbol_count = static_cast<uint32_t>(symbols.size());
  MoveToBinaryFormat(symbol_count, p);
  for (const auto& symbol : symbols) {
    MoveToBinaryFormat(symbol->addr, p);
    uint32_t len = symbol->len;
    MoveToBinaryFormat(len, p);
    MoveToBinaryFormat(symbol->Name(), strlen(symbol->Name()) + 1, p);
  }
  CHECK_EQ(buf.size(), static_cast<size_t>(p - buf.data()));

  if (!WriteFeatureBegin(FEAT_FILE)) {
    return false;
  }
  if (!Write(buf.data(), buf.size())) {
    return false;
  }
  return WriteFeatureEnd(FEAT_FILE);
}

bool RecordFileWriter::WriteFeatureBegin(int feature) {
  auto it = features_.find(feature);
  if (it == features_.end()) {
    CHECK_LT(features_.size(), feature_count_);
    auto& sec = features_[feature];
    if (!GetFilePos(&sec.offset)) {
      return false;
    }
    sec.size = 0;
  }
  return true;
}

bool RecordFileWriter::WriteFeatureEnd(int feature) {
  auto it = features_.find(feature);
  if (it == features_.end()) {
    return false;
  }
  uint64_t offset;
  if (!GetFilePos(&offset)) {
    return false;
  }
  it->second.size = offset - it->second.offset;
  return true;
}

bool RecordFileWriter::EndWriteFeatures() {
  // Used features (features_.size()) should be <= allocated feature space.
  CHECK_LE(features_.size(), feature_count_);
  if (fseek(record_fp_, feature_section_offset_, SEEK_SET) == -1) {
    PLOG(ERROR) << "fseek() failed";
    return false;
  }
  for (const auto& pair : features_) {
    if (!Write(&pair.second, sizeof(SectionDesc))) {
      return false;
    }
  }
  return true;
}

bool RecordFileWriter::WriteFileHeader() {
  FileHeader header;
  memset(&header, 0, sizeof(header));
  memcpy(header.magic, PERF_MAGIC, sizeof(header.magic));
  header.header_size = sizeof(header);
  header.attr_size = sizeof(FileAttr);
  header.attrs.offset = attr_section_offset_;
  header.attrs.size = attr_section_size_;
  header.data.offset = data_section_offset_;
  header.data.size = data_section_size_;
  for (const auto& pair : features_) {
    int i = pair.first / 8;
    int j = pair.first % 8;
    header.features[i] |= (1 << j);
  }

  if (fseek(record_fp_, 0, SEEK_SET) == -1) {
    return false;
  }
  if (!Write(&header, sizeof(header))) {
    return false;
  }
  return true;
}

bool RecordFileWriter::Close() {
  CHECK(record_fp_ != nullptr);
  bool result = true;

  // Write file header. We gather enough information to write file header only after
  // writing data section and feature section.
  if (!WriteFileHeader()) {
    result = false;
  }

  if (fclose(record_fp_) != 0) {
    PLOG(ERROR) << "failed to close record file '" << filename_ << "'";
    result = false;
  }
  record_fp_ = nullptr;
  return result;
}