filesystem_copier_action.cc

// Copyright (c) 2010 The Chromium OS 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 "update_engine/filesystem_copier_action.h"

#include <sys/stat.h>
#include <sys/types.h>
#include <errno.h>
#include <fcntl.h>

#include <algorithm>
#include <cstdlib>
#include <map>
#include <string>
#include <vector>

#include <gio/gio.h>
#include <gio/gunixinputstream.h>
#include <gio/gunixoutputstream.h>
#include <glib.h>

#include "update_engine/filesystem_iterator.h"
#include "update_engine/subprocess.h"
#include "update_engine/utils.h"

using std::map;
using std::min;
using std::string;
using std::vector;

namespace chromeos_update_engine {

namespace {
const off_t kCopyFileBufferSize = 512 * 1024;
}  // namespace {}

FilesystemCopierAction::FilesystemCopierAction(
    bool copying_kernel_install_path)
    : copying_kernel_install_path_(copying_kernel_install_path),
      src_stream_(NULL),
      dst_stream_(NULL),
      read_done_(false),
      failed_(false),
      cancelled_(false),
      filesystem_size_(kint64max) {
  // A lot of code works on the implicit assumption that processing is done on
  // exactly 2 ping-pong buffers.
  COMPILE_ASSERT(arraysize(buffer_) == 2 &&
                 arraysize(buffer_state_) == 2 &&
                 arraysize(buffer_valid_size_) == 2 &&
                 arraysize(canceller_) == 2,
                 ping_pong_buffers_not_two);
  for (int i = 0; i < 2; ++i) {
    buffer_state_[i] = kBufferStateEmpty;
    buffer_valid_size_[i] = 0;
    canceller_[i] = NULL;
  }
}

void FilesystemCopierAction::PerformAction() {
  // Will tell the ActionProcessor we've failed if we return.
  ScopedActionCompleter abort_action_completer(processor_, this);

  if (!HasInputObject()) {
    LOG(ERROR) << "FilesystemCopierAction missing input object.";
    return;
  }
  install_plan_ = GetInputObject();

  if (install_plan_.is_full_update || install_plan_.is_resume) {
    // No copy needed. Done!
    if (HasOutputPipe())
      SetOutputObject(install_plan_);
    abort_action_completer.set_code(kActionCodeSuccess);
    return;
  }

  string source = copy_source_;
  if (source.empty()) {
    source = copying_kernel_install_path_ ?
        utils::BootKernelDevice(utils::BootDevice()) :
        utils::BootDevice();
  }

  const string destination = copying_kernel_install_path_ ?
      install_plan_.kernel_install_path :
      install_plan_.install_path;

  int src_fd = open(source.c_str(), O_RDONLY);
  if (src_fd < 0) {
    PLOG(ERROR) << "Unable to open " << source << " for reading:";
    return;
  }
  int dst_fd = open(destination.c_str(),
                    O_WRONLY | O_TRUNC | O_CREAT,
                    0644);
  if (dst_fd < 0) {
    close(src_fd);
    PLOG(ERROR) << "Unable to open " << install_plan_.install_path
                << " for writing:";
    return;
  }

  DetermineFilesystemSize(src_fd);

  src_stream_ = g_unix_input_stream_new(src_fd, TRUE);
  dst_stream_ = g_unix_output_stream_new(dst_fd, TRUE);

  for (int i = 0; i < 2; i++) {
    buffer_[i].resize(kCopyFileBufferSize);
    canceller_[i] = g_cancellable_new();
  }

  // Start the first read.
  SpawnAsyncActions();

  abort_action_completer.set_should_complete(false);
}

void FilesystemCopierAction::TerminateProcessing() {
  for (int i = 0; i < 2; i++) {
    if (canceller_[i]) {
      g_cancellable_cancel(canceller_[i]);
    }
  }
}

void FilesystemCopierAction::Cleanup(bool success) {
  for (int i = 0; i < 2; i++) {
    g_object_unref(canceller_[i]);
    canceller_[i] = NULL;
  }
  g_object_unref(src_stream_);
  src_stream_ = NULL;
  g_object_unref(dst_stream_);
  dst_stream_ = NULL;
  if (cancelled_)
    return;
  if (success && HasOutputPipe())
    SetOutputObject(install_plan_);
  processor_->ActionComplete(
      this,
      success ? kActionCodeSuccess : kActionCodeError);
}

void FilesystemCopierAction::AsyncReadReadyCallback(GObject *source_object,
                                                    GAsyncResult *res) {
  int index = buffer_state_[0] == kBufferStateReading ? 0 : 1;
  CHECK(buffer_state_[index] == kBufferStateReading);

  GError* error = NULL;
  CHECK(canceller_[index]);
  cancelled_ = g_cancellable_is_cancelled(canceller_[index]) == TRUE;

  ssize_t bytes_read = g_input_stream_read_finish(src_stream_, res, &error);
  if (bytes_read < 0) {
    LOG(ERROR) << "Read failed: " << utils::GetGErrorMessage(error);
    failed_ = true;
    buffer_state_[index] = kBufferStateEmpty;
  } else if (bytes_read == 0) {
    read_done_ = true;
    buffer_state_[index] = kBufferStateEmpty;
  } else {
    buffer_valid_size_[index] = bytes_read;
    buffer_state_[index] = kBufferStateFull;
  }

  if (bytes_read > 0) {
    filesystem_size_ -= bytes_read;
  }

  SpawnAsyncActions();

  if (bytes_read > 0) {
    if (!hasher_.Update(buffer_[index].data(), bytes_read)) {
      LOG(ERROR) << "Unable to update the hash.";
      failed_ = true;
    }
  }
}

void FilesystemCopierAction::StaticAsyncReadReadyCallback(
    GObject *source_object,
    GAsyncResult *res,
    gpointer user_data) {
  reinterpret_cast<FilesystemCopierAction*>(user_data)->
      AsyncReadReadyCallback(source_object, res);
}

void FilesystemCopierAction::AsyncWriteReadyCallback(GObject *source_object,
                                                     GAsyncResult *res) {
  int index = buffer_state_[0] == kBufferStateWriting ? 0 : 1;
  CHECK(buffer_state_[index] == kBufferStateWriting);
  buffer_state_[index] = kBufferStateEmpty;

  GError* error = NULL;
  CHECK(canceller_[index]);
  cancelled_ = g_cancellable_is_cancelled(canceller_[index]) == TRUE;

  ssize_t bytes_written = g_output_stream_write_finish(dst_stream_,
                                                       res,
                                                       &error);
  if (bytes_written < static_cast<ssize_t>(buffer_valid_size_[index])) {
    if (bytes_written < 0) {
      LOG(ERROR) << "Write failed: " << utils::GetGErrorMessage(error);
    } else {
      LOG(ERROR) << "Write was short: wrote " << bytes_written
                 << " but expected to write " << buffer_valid_size_[index];
    }
    failed_ = true;
  }

  SpawnAsyncActions();
}

void FilesystemCopierAction::StaticAsyncWriteReadyCallback(
    GObject *source_object,
    GAsyncResult *res,
    gpointer user_data) {
  reinterpret_cast<FilesystemCopierAction*>(user_data)->
      AsyncWriteReadyCallback(source_object, res);
}

void FilesystemCopierAction::SpawnAsyncActions() {
  bool reading = false;
  bool writing = false;
  for (int i = 0; i < 2; i++) {
    if (buffer_state_[i] == kBufferStateReading) {
      reading = true;
    }
    if (buffer_state_[i] == kBufferStateWriting) {
      writing = true;
    }
  }
  if (failed_ || cancelled_) {
    if (!reading && !writing) {
      Cleanup(false);
    }
    return;
  }
  for (int i = 0; i < 2; i++) {
    if (!reading && !read_done_ && buffer_state_[i] == kBufferStateEmpty) {
      g_input_stream_read_async(
          src_stream_,
          buffer_[i].data(),
          GetBytesToRead(),
          G_PRIORITY_DEFAULT,
          canceller_[i],
          &FilesystemCopierAction::StaticAsyncReadReadyCallback,
          this);
      reading = true;
      buffer_state_[i] = kBufferStateReading;
    } else if (!writing && buffer_state_[i] == kBufferStateFull) {
      g_output_stream_write_async(
          dst_stream_,
          buffer_[i].data(),
          buffer_valid_size_[i],
          G_PRIORITY_DEFAULT,
          canceller_[i],
          &FilesystemCopierAction::StaticAsyncWriteReadyCallback,
          this);
      writing = true;
      buffer_state_[i] = kBufferStateWriting;
    }
  }
  if (!reading && !writing) {
    // We're done!
    if (hasher_.Finalize()) {
      LOG(INFO) << "hash: " << hasher_.hash();
      if (copying_kernel_install_path_) {
        install_plan_.current_kernel_hash = hasher_.raw_hash();
      } else {
        install_plan_.current_rootfs_hash = hasher_.raw_hash();
      }
      Cleanup(true);
    } else {
      LOG(ERROR) << "Unable to finalize the hash.";
      Cleanup(false);
    }
  }
}

void FilesystemCopierAction::DetermineFilesystemSize(int fd) {
  filesystem_size_ = kint64max;
  int block_count = 0, block_size = 0;
  if (!copying_kernel_install_path_ &&
      utils::GetFilesystemSizeFromFD(fd, &block_count, &block_size)) {
    filesystem_size_ = static_cast<int64_t>(block_count) * block_size;
    LOG(INFO) << "Filesystem size: " << filesystem_size_ << " bytes ("
              << block_count << "x" << block_size << ").";
  }
}

int64_t FilesystemCopierAction::GetBytesToRead() {
  return std::min(static_cast<int64_t>(buffer_[0].size()), filesystem_size_);
}

}  // namespace chromeos_update_engine