// Copyright 2017 The Bazel Authors. All rights reserved.
//
// 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.

package com.google.devtools.build.lib.sandbox;

import com.google.devtools.build.lib.actions.ExecException;
import com.google.devtools.build.lib.actions.Spawn;
import com.google.devtools.build.lib.exec.TreeDeleter;
import com.google.devtools.build.lib.exec.local.LocalEnvProvider;
import com.google.devtools.build.lib.runtime.CommandEnvironment;
import com.google.devtools.build.lib.runtime.ProcessWrapperUtil;
import com.google.devtools.build.lib.util.OS;
import com.google.devtools.build.lib.vfs.Path;
import java.io.IOException;
import java.time.Duration;
import java.util.Map;

/** Strategy that uses sandboxing to execute a process. */
final class ProcessWrapperSandboxedSpawnRunner extends AbstractSandboxSpawnRunner {

  public static boolean isSupported(CommandEnvironment cmdEnv) {
    return OS.isPosixCompatible() && ProcessWrapperUtil.isSupported(cmdEnv);
  }

  private final Path processWrapper;
  private final Path execRoot;
  private final Path sandboxBase;
  private final LocalEnvProvider localEnvProvider;
  private final Duration timeoutKillDelay;
  private final TreeDeleter treeDeleter;

  /**
   * Creates a sandboxed spawn runner that uses the {@code process-wrapper} tool.
   *
   * @param cmdEnv the command environment to use
   * @param sandboxBase path to the sandbox base directory
   * @param productName the product name to use
   * @param timeoutKillDelay additional grace period before killing timing out commands
   */
  ProcessWrapperSandboxedSpawnRunner(
      CommandEnvironment cmdEnv,
      Path sandboxBase,
      String productName,
      Duration timeoutKillDelay,
      TreeDeleter treeDeleter) {
    super(cmdEnv);
    this.processWrapper = ProcessWrapperUtil.getProcessWrapper(cmdEnv);
    this.execRoot = cmdEnv.getExecRoot();
    this.localEnvProvider = LocalEnvProvider.forCurrentOs(cmdEnv.getClientEnv());
    this.sandboxBase = sandboxBase;
    this.timeoutKillDelay = timeoutKillDelay;
    this.treeDeleter = treeDeleter;
  }

  @Override
  protected SandboxedSpawn prepareSpawn(Spawn spawn, SpawnExecutionContext context)
      throws IOException, ExecException {
    // Each invocation of "exec" gets its own sandbox base.
    // Note that the value returned by context.getId() is only unique inside one given SpawnRunner,
    // so we have to prefix our name to turn it into a globally unique value.
    Path sandboxPath =
        sandboxBase.getRelative(getName()).getRelative(Integer.toString(context.getId()));
    sandboxPath.getParentDirectory().createDirectory();
    sandboxPath.createDirectory();

    // b/64689608: The execroot of the sandboxed process must end with the workspace name, just like
    // the normal execroot does.
    Path sandboxExecRoot = sandboxPath.getRelative("execroot").getRelative(execRoot.getBaseName());
    sandboxExecRoot.getParentDirectory().createDirectory();
    sandboxExecRoot.createDirectory();

    Map<String, String> environment =
        localEnvProvider.rewriteLocalEnv(spawn.getEnvironment(), binTools, "/tmp");

    Duration timeout = context.getTimeout();
    ProcessWrapperUtil.CommandLineBuilder commandLineBuilder =
        ProcessWrapperUtil.commandLineBuilder(processWrapper.getPathString(), spawn.getArguments())
            .setTimeout(timeout);

    commandLineBuilder.setKillDelay(timeoutKillDelay);

    Path statisticsPath = null;
    if (getSandboxOptions().collectLocalSandboxExecutionStatistics) {
      statisticsPath = sandboxPath.getRelative("stats.out");
      commandLineBuilder.setStatisticsPath(statisticsPath);
    }

    return new SymlinkedSandboxedSpawn(
        sandboxPath,
        sandboxExecRoot,
        commandLineBuilder.build(),
        environment,
        SandboxHelpers.processInputFiles(
            spawn,
            context,
            execRoot,
            getSandboxOptions().symlinkedSandboxExpandsTreeArtifactsInRunfilesTree),
        SandboxHelpers.getOutputs(spawn),
        getWritableDirs(sandboxExecRoot, environment),
        treeDeleter,
        statisticsPath);
  }

  @Override
  public String getName() {
    return "processwrapper-sandbox";
  }
}