| // 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 static com.google.common.base.Preconditions.checkNotNull; |
| import static java.nio.charset.StandardCharsets.UTF_8; |
| |
| import com.google.common.collect.ImmutableList; |
| import com.google.common.collect.ImmutableMap; |
| import com.google.devtools.build.lib.shell.Subprocess; |
| import com.google.devtools.build.lib.shell.SubprocessBuilder; |
| import com.google.devtools.build.lib.util.OS; |
| import com.google.devtools.build.lib.vfs.Path; |
| import com.google.devtools.build.lib.vfs.PathFragment; |
| import java.io.BufferedReader; |
| import java.io.BufferedWriter; |
| import java.io.IOException; |
| import java.io.InputStreamReader; |
| import java.io.OutputStreamWriter; |
| import java.util.List; |
| import java.util.function.Function; |
| import java.util.logging.Logger; |
| import java.util.stream.Collectors; |
| import javax.annotation.Nullable; |
| |
| /** A sandboxfs implementation that uses an external sandboxfs binary to manage the mount point. */ |
| final class RealSandboxfsProcess implements SandboxfsProcess { |
| private static final Logger log = Logger.getLogger(RealSandboxfsProcess.class.getName()); |
| |
| /** Directory on which the sandboxfs is serving. */ |
| private final Path mountPoint; |
| |
| /** |
| * Process handle to the sandboxfs instance. Null only after {@link #destroy()} has been invoked. |
| */ |
| private @Nullable Subprocess process; |
| |
| /** |
| * Writer with which to send data to the sandboxfs instance. Null only after {@link #destroy()} |
| * has been invoked. |
| */ |
| private @Nullable BufferedWriter processStdIn; |
| |
| /** |
| * Reader with which to receive data from the sandboxfs instance. Null only after |
| * {@link #destroy()} has been invoked. |
| */ |
| private @Nullable BufferedReader processStdOut; |
| |
| /** |
| * Shutdown hook to stop the sandboxfs instance on abrupt termination. Null only after |
| * {@link #destroy()} has been invoked. |
| */ |
| private @Nullable Thread shutdownHook; |
| |
| /** |
| * Initializes a new sandboxfs process instance. |
| * |
| * @param process process handle for the already-running sandboxfs instance |
| */ |
| private RealSandboxfsProcess(Path mountPoint, Subprocess process) { |
| this.mountPoint = mountPoint; |
| |
| this.process = process; |
| this.processStdIn = new BufferedWriter( |
| new OutputStreamWriter(process.getOutputStream(), UTF_8)); |
| this.processStdOut = new BufferedReader( |
| new InputStreamReader(process.getInputStream(), UTF_8)); |
| |
| this.shutdownHook = |
| new Thread( |
| () -> { |
| try { |
| this.destroy(); |
| } catch (Exception e) { |
| log.warning("Failed to destroy running sandboxfs instance; mount point may have " |
| + "been left behind: " + e); |
| } |
| }); |
| Runtime.getRuntime().addShutdownHook(shutdownHook); |
| } |
| |
| /** |
| * Mounts a new sandboxfs instance. |
| * |
| * <p>The root of the file system instance is left unmapped which means that it remains as |
| * read-only throughout the lifetime of this instance. Writable subdirectories can later be |
| * mapped via {@link #map(List)}. |
| * |
| * @param binary path to the sandboxfs binary. This is a {@link PathFragment} and not a |
| * {@link Path} because we want to support "bare" (non-absolute) names for the location of |
| * the sandboxfs binary; such names are automatically looked for in the {@code PATH}. |
| * @param mountPoint directory on which to mount the sandboxfs instance |
| * @param logFile path to the file that will receive all sandboxfs logging output |
| * @return a new handle that represents the running process |
| * @throws IOException if there is a problem starting the process |
| */ |
| static SandboxfsProcess mount(PathFragment binary, Path mountPoint, Path logFile) |
| throws IOException { |
| log.info("Mounting sandboxfs (" + binary + ") onto " + mountPoint); |
| |
| // TODO(jmmv): Before starting a sandboxfs serving instance, we must query the current version |
| // of sandboxfs and check if we support its communication protocol. |
| |
| ImmutableList.Builder<String> argvBuilder = ImmutableList.builder(); |
| |
| argvBuilder.add(binary.getPathString()); |
| |
| // On macOS, we need to allow users other than self to access the sandboxfs instance. This is |
| // necessary because macOS's amfid, which runs as root, has to have access to the binaries |
| // within the sandbox in order to validate signatures. See: |
| // http://julio.meroh.net/2017/10/fighting-execs-sandboxfs-macos.html |
| argvBuilder.add(OS.getCurrent() == OS.DARWIN ? "--allow=other" : "--allow=self"); |
| |
| // TODO(jmmv): Pass flags to enable sandboxfs' debugging support (--listen_address and --debug) |
| // when requested by the user via --sandbox_debug. Tricky because we have to figure out how to |
| // deal with port numbers (which sandboxfs can autoassign, but doesn't currently promise a way |
| // to tell us back what it picked). |
| |
| argvBuilder.add(mountPoint.getPathString()); |
| |
| SubprocessBuilder processBuilder = new SubprocessBuilder(); |
| processBuilder.setArgv(argvBuilder.build()); |
| processBuilder.setStderr(logFile.getPathFile()); |
| processBuilder.setEnv(ImmutableMap.of( |
| // sandboxfs may need to locate fusermount depending on the FUSE implementation so pass the |
| // PATH to the subprocess (which we assume is sufficient). |
| "PATH", System.getenv("PATH"))); |
| |
| Subprocess process = processBuilder.start(); |
| RealSandboxfsProcess sandboxfs = new RealSandboxfsProcess(mountPoint, process); |
| // TODO(jmmv): We should have a better mechanism to wait for sandboxfs to start successfully but |
| // sandboxfs currently provides no interface to do so. Just try to push an empty configuration |
| // and see if it works. |
| try { |
| sandboxfs.reconfigure("[]\n\n"); |
| } catch (IOException e) { |
| destroyProcess(process); |
| throw new IOException("sandboxfs failed to start", e); |
| } |
| return sandboxfs; |
| } |
| |
| @Override |
| public Path getMountPoint() { |
| return mountPoint; |
| } |
| |
| @Override |
| public boolean isAlive() { |
| return process != null && !process.finished(); |
| } |
| |
| /** |
| * Destroys a process and waits for it to exit. |
| * |
| * @param process the process to destroy. |
| */ |
| // TODO(jmmv): This is adapted from Worker.java. Should probably replace both with a new variant |
| // of Uninterruptibles.callUninterruptibly that takes a lambda instead of a callable. |
| private static void destroyProcess(Subprocess process) { |
| process.destroy(); |
| |
| boolean interrupted = false; |
| try { |
| while (true) { |
| try { |
| process.waitFor(); |
| return; |
| } catch (InterruptedException ie) { |
| interrupted = true; |
| } |
| } |
| } finally { |
| if (interrupted) { |
| Thread.currentThread().interrupt(); |
| } |
| } |
| } |
| |
| @Override |
| public synchronized void destroy() { |
| if (shutdownHook != null) { |
| Runtime.getRuntime().removeShutdownHook(shutdownHook); |
| shutdownHook = null; |
| } |
| |
| if (processStdIn != null) { |
| try { |
| processStdIn.close(); |
| } catch (IOException e) { |
| log.warning("Failed to close sandboxfs's stdin pipe: " + e); |
| } |
| processStdIn = null; |
| } |
| |
| if (processStdOut != null) { |
| try { |
| processStdOut.close(); |
| } catch (IOException e) { |
| log.warning("Failed to close sandboxfs's stdout pipe: " + e); |
| } |
| processStdOut = null; |
| } |
| |
| if (process != null) { |
| destroyProcess(process); |
| process = null; |
| } |
| } |
| |
| /** |
| * Pushes a new configuration to sandboxfs and waits for acceptance. |
| * |
| * @param config the configuration chunk to push to sandboxfs |
| * @throws IOException if sandboxfs cannot be reconfigured either because of an error in the |
| * configuration or because we failed to communicate with the subprocess |
| */ |
| private synchronized void reconfigure(String config) throws IOException { |
| checkNotNull(processStdIn, "sandboxfs already has been destroyed"); |
| processStdIn.write(config); |
| processStdIn.flush(); |
| |
| checkNotNull(processStdOut, "sandboxfs has already been destroyed"); |
| String done = processStdOut.readLine(); |
| if (done == null) { |
| throw new IOException("premature end of output from sandboxfs"); |
| } |
| if (!done.equals("Done")) { |
| throw new IOException("received unknown string from sandboxfs: " + done + "; expected Done"); |
| } |
| } |
| |
| @Override |
| public void map(List<Mapping> mappings) throws IOException { |
| Function<Mapping, String> formatMapping = |
| (mapping) -> String.format( |
| "{\"Map\": {\"Mapping\": \"%s\", \"Target\": \"%s\", \"Writable\": %s}}", |
| mapping.path(), mapping.target(), mapping.writable() ? "true" : "false"); |
| |
| StringBuilder sb = new StringBuilder(); |
| sb.append("[\n"); |
| sb.append(mappings.stream().map(formatMapping).collect(Collectors.joining(",\n"))); |
| sb.append("]\n\n"); |
| reconfigure(sb.toString()); |
| } |
| |
| @Override |
| public void unmap(PathFragment mapping) throws IOException { |
| reconfigure(String.format("[{\"Unmap\": \"%s\"}]\n\n", mapping)); |
| } |
| } |