| // Copyright 2017 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 "garnet/bin/ktrace_provider/reader.h" |
| |
| #include <fcntl.h> |
| #include <limits.h> |
| #include <sys/stat.h> |
| #include <unistd.h> |
| |
| #include "lib/fxl/files/eintr_wrapper.h" |
| |
| namespace ktrace_provider { |
| namespace { |
| |
| constexpr char kTraceDev[] = "/dev/misc/ktrace"; |
| |
| } // namespace |
| |
| Reader::Reader() : fd_(open(kTraceDev, O_RDONLY)) {} |
| |
| ktrace_header_t* Reader::ReadNextRecord() { |
| if (AvailableBytes() < sizeof(ktrace_header_t)) |
| ReadMoreData(); |
| |
| if (AvailableBytes() < sizeof(ktrace_header_t)) |
| return nullptr; |
| |
| auto record = reinterpret_cast<ktrace_header_t*>(current_); |
| |
| if (AvailableBytes() < KTRACE_LEN(record->tag)) |
| ReadMoreData(); |
| |
| if (AvailableBytes() < KTRACE_LEN(record->tag)) |
| return nullptr; |
| |
| record = reinterpret_cast<ktrace_header_t*>(current_); |
| current_ += KTRACE_LEN(record->tag); |
| |
| number_bytes_read_ += KTRACE_LEN(record->tag); |
| number_records_read_ += 1; |
| return record; |
| } |
| |
| void Reader::ReadMoreData() { |
| memcpy(buffer_, current_, AvailableBytes()); |
| marker_ = buffer_ + AvailableBytes(); |
| |
| while (marker_ < end_) { |
| int bytes_read = |
| HANDLE_EINTR(read(fd_.get(), marker_, std::distance(marker_, end_))); |
| |
| if (bytes_read <= 0) |
| break; |
| |
| marker_ += bytes_read; |
| } |
| |
| current_ = buffer_; |
| } |
| |
| } // namespace ktrace_provider |