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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.
}
}
}
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