com.google.devtools.build.lib.sandbox.AbstractContainerizingSandboxedSpawn.java Source code

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Here is the source code for com.google.devtools.build.lib.sandbox.AbstractContainerizingSandboxedSpawn.java

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// Copyright 2018 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.common.base.Preconditions;
import com.google.common.collect.Iterables;
import com.google.devtools.build.lib.vfs.FileSystemUtils;
import com.google.devtools.build.lib.vfs.Path;
import com.google.devtools.build.lib.vfs.PathFragment;
import java.io.IOException;
import java.util.Collection;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;

/**
 * Implements the general flow of a sandboxed spawn that uses a container directory to build an
 * execution root for a spawn.
 */
public abstract class AbstractContainerizingSandboxedSpawn implements SandboxedSpawn {
    private final Path sandboxPath;
    private final Path sandboxExecRoot;
    private final List<String> arguments;
    private final Map<String, String> environment;
    private final Map<PathFragment, Path> inputs;
    private final Collection<PathFragment> outputs;
    private final Set<Path> writableDirs;

    public AbstractContainerizingSandboxedSpawn(Path sandboxPath, Path sandboxExecRoot, List<String> arguments,
            Map<String, String> environment, Map<PathFragment, Path> inputs, Collection<PathFragment> outputs,
            Set<Path> writableDirs) {
        this.sandboxPath = sandboxPath;
        this.sandboxExecRoot = sandboxExecRoot;
        this.arguments = arguments;
        this.environment = environment;
        this.inputs = inputs;
        this.outputs = outputs;
        this.writableDirs = writableDirs;
    }

    @Override
    public Path getSandboxExecRoot() {
        return sandboxExecRoot;
    }

    @Override
    public List<String> getArguments() {
        return arguments;
    }

    @Override
    public Map<String, String> getEnvironment() {
        return environment;
    }

    @Override
    public void createFileSystem() throws IOException {
        createDirectories();
        createInputs(inputs);
    }

    /**
     * No input can be a child of another input, because otherwise we might try to create a symlink
     * below another symlink we created earlier - which means we'd actually end up writing somewhere
     * in the workspace.
     *
     * <p>If all inputs were regular files, this situation could naturally not happen - but
     * unfortunately, we might get the occasional action that has directories in its inputs.
     *
     * <p>Creating all parent directories first ensures that we can safely create symlinks to
     * directories, too, because we'll get an IOException with EEXIST if inputs happen to be nested
     * once we start creating the symlinks for all inputs.
     */
    private void createDirectories() throws IOException {
        LinkedHashSet<Path> dirsToCreate = new LinkedHashSet<>();

        for (PathFragment path : Iterables.concat(inputs.keySet(), outputs)) {
            Preconditions.checkArgument(!path.isAbsolute());
            Preconditions.checkArgument(!path.containsUplevelReferences());
            for (int i = 0; i < path.segmentCount(); i++) {
                dirsToCreate.add(sandboxExecRoot.getRelative(path.subFragment(0, i)));
            }
        }

        for (Path path : dirsToCreate) {
            path.createDirectory();
        }

        for (Path dir : writableDirs) {
            if (dir.startsWith(sandboxExecRoot)) {
                dir.createDirectoryAndParents();
            }
        }
    }

    protected void createInputs(Map<PathFragment, Path> inputs) throws IOException {
        // All input files are relative to the execroot.
        for (Map.Entry<PathFragment, Path> entry : inputs.entrySet()) {
            Path key = sandboxExecRoot.getRelative(entry.getKey());
            // A null value means that we're supposed to create an empty file as the input.
            if (entry.getValue() != null) {
                copyFile(entry.getValue(), key);
            } else {
                FileSystemUtils.createEmptyFile(key);
            }
        }
    }

    protected abstract void copyFile(Path source, Path target) throws IOException;

    @Override
    public void copyOutputs(Path execRoot) throws IOException {
        SandboxedSpawn.moveOutputs(outputs, sandboxExecRoot, execRoot);
    }

    @Override
    public void delete() {
        try {
            FileSystemUtils.deleteTree(sandboxPath);
        } catch (IOException e) {
            // This usually means that the Spawn itself exited, but still has children running that
            // we couldn't wait for, which now block deletion of the sandbox directory. On Linux this
            // should never happen, as we use PID namespaces and where they are not available the
            // subreaper feature to make sure all children have been reliably killed before returning,
            // but on other OS this might not always work. The SandboxModule will try to delete them
            // again when the build is all done, at which point it hopefully works, so let's just go
            // on here.
        }
    }
}