zircon/system/ulib/trace-reader/file_reader.cc

// Copyright 2019 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include <trace-reader/file_reader.h>

namespace trace {

// static
bool FileReader::Create(const char* file_path, RecordConsumer record_consumer,
                        ErrorHandler error_handler, std::unique_ptr<FileReader>* out_reader) {
  ZX_DEBUG_ASSERT(out_reader != nullptr);

  FILE* f = fopen(file_path, "rb");
  if (f == nullptr) {
    return false;
  }

  out_reader->reset(new FileReader(f, std::move(record_consumer), std::move(error_handler)));
  return true;
}

FileReader::FileReader(FILE* file, RecordConsumer record_consumer, ErrorHandler error_handler)
    : TraceReader(std::move(record_consumer), std::move(error_handler)), file_(file) {}

void FileReader::ReadFile() {
  for (;;) {
    size_t to_read = buffer_.size() - buffer_end_;
    size_t actual = fread(buffer_.data() + buffer_end_, 1u, to_read, file_);

    if (actual == 0) {
      break;
    }

    buffer_end_ += actual;
    size_t bytes_available = buffer_end_;

    size_t bytes_consumed;
    trace::Chunk chunk(reinterpret_cast<const uint64_t*>(buffer_.data()),
                       trace::BytesToWords(bytes_available));
    if (!ReadRecords(chunk)) {
      ReportError("Trace stream is corrupted");
      break;
    }
    bytes_consumed = bytes_available - trace::WordsToBytes(chunk.remaining_words());

    bytes_available -= bytes_consumed;
    memmove(buffer_.data(), buffer_.data() + bytes_consumed, bytes_available);
    buffer_end_ = bytes_available;
  }
}

}  // namespace trace