Use linux-sandbox via the (new) LinuxSandboxUtil. (second attempt).

RELNOTES: None.
PiperOrigin-RevId: 179705357

2 files changed, 288 insertions, 74 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/runtime/LinuxSandboxUtil.java b/src/main/java/com/google/devtools/build/lib/runtime/LinuxSandboxUtil.java
new file mode 100644
index 0000000000..97d6427400
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/runtime/LinuxSandboxUtil.java
@@ -0,0 +1,264 @@
+// 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.runtime;
+
+import com.google.common.base.Preconditions;
+import com.google.common.collect.ImmutableList;
+import com.google.devtools.build.lib.util.OsUtils;
+import com.google.devtools.build.lib.vfs.Path;
+import com.google.devtools.build.lib.vfs.PathFragment;
+import java.time.Duration;
+import java.util.Collection;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+
+/** Utility functions for the {@code linux-sandbox} embedded tool. */
+public final class LinuxSandboxUtil {
+  private static final String LINUX_SANDBOX = "linux-sandbox" + OsUtils.executableExtension();
+
+  /** Returns whether using the {@code linux-sandbox} is supported in the command environment. */
+  public static boolean isSupported(CommandEnvironment cmdEnv) {
+    // We can only use the linux-sandbox if the linux-sandbox exists in the embedded tools.
+    // This might not always be the case, e.g. while bootstrapping.
+    return getLinuxSandbox(cmdEnv) != null;
+  }
+
+  /** Returns the path of the {@code linux-sandbox} binary, or null if it doesn't exist. */
+  public static Path getLinuxSandbox(CommandEnvironment cmdEnv) {
+    PathFragment execPath = cmdEnv.getBlazeWorkspace().getBinTools().getExecPath(LINUX_SANDBOX);
+    return execPath != null ? cmdEnv.getExecRoot().getRelative(execPath) : null;
+  }
+
+  /** Returns a new command line builder for the {@code linux-sandbox} tool. */
+  public static CommandLineBuilder commandLineBuilder(
+      String linuxSandboxPath, Collection<String> commandArguments) {
+    return new CommandLineBuilder()
+        .setLinuxSandboxPath(linuxSandboxPath)
+        .setCommandArguments(commandArguments);
+  }
+
+  /**
+   * A builder class for constructing the full command line to run a command using the {@code
+   * linux-sandbox} tool.
+   */
+  public static class CommandLineBuilder {
+    // TODO(b/62588075): Reconsider using Path/PathFragment instead of Strings for file paths.
+    private Optional<String> linuxSandboxPath = Optional.empty();
+    private Optional<String> workingDirectory = Optional.empty();
+    private Optional<Duration> timeout = Optional.empty();
+    private Optional<Duration> killDelay = Optional.empty();
+    private Optional<String> stdoutPath = Optional.empty();
+    private Optional<String> stderrPath = Optional.empty();
+    private Optional<Iterable<Path>> writableFilesAndDirectories = Optional.empty();
+    private Optional<Iterable<Path>> tmpfsDirectories = Optional.empty();
+    private Optional<Map<Path, Path>> bindMounts = Optional.empty();
+    private Optional<String> statisticsPath = Optional.empty();
+    private boolean useFakeHostname = false;
+    private boolean createNetworkNamespace = false;
+    private boolean useFakeRoot = false;
+    private boolean useFakeUsername = false;
+    private boolean useDebugMode = false;
+    private Optional<Collection<String>> commandArguments = Optional.empty();
+
+    private CommandLineBuilder() {
+      // Prevent external construction via "new".
+    }
+
+    /** Sets the path of the {@code linux-sandbox} tool. */
+    public CommandLineBuilder setLinuxSandboxPath(String linuxSandboxPath) {
+      this.linuxSandboxPath = Optional.of(linuxSandboxPath);
+      return this;
+    }
+
+    /** Sets the working directory to use, if any. */
+    public CommandLineBuilder setWorkingDirectory(String workingDirectory) {
+      this.workingDirectory = Optional.of(workingDirectory);
+      return this;
+    }
+
+    /** Sets the timeout for the command run using the {@code linux-sandbox} tool. */
+    public CommandLineBuilder setTimeout(Duration timeout) {
+      this.timeout = Optional.of(timeout);
+      return this;
+    }
+
+    /**
+     * Sets the kill delay for commands run using the {@code linux-sandbox} tool that exceed their
+     * timeout.
+     */
+    public CommandLineBuilder setKillDelay(Duration killDelay) {
+      this.killDelay = Optional.of(killDelay);
+      return this;
+    }
+
+    /** Sets the path to use for redirecting stdout, if any. */
+    public CommandLineBuilder setStdoutPath(String stdoutPath) {
+      this.stdoutPath = Optional.of(stdoutPath);
+      return this;
+    }
+
+    /** Sets the path to use for redirecting stderr, if any. */
+    public CommandLineBuilder setStderrPath(String stderrPath) {
+      this.stderrPath = Optional.of(stderrPath);
+      return this;
+    }
+
+    /** Sets the files or directories to make writable for the sandboxed process, if any. */
+    public CommandLineBuilder setWritableFilesAndDirectories(
+        Iterable<Path> writableFilesAndDirectories) {
+      this.writableFilesAndDirectories = Optional.of(writableFilesAndDirectories);
+      return this;
+    }
+
+    /** Sets the directories where to mount an empty tmpfs, if any. */
+    public CommandLineBuilder setTmpfsDirectories(Iterable<Path> tmpfsDirectories) {
+      this.tmpfsDirectories = Optional.of(tmpfsDirectories);
+      return this;
+    }
+
+    /**
+     * Sets the sources and targets of files or directories to explicitly bind-mount in the sandbox,
+     * if any.
+     */
+    public CommandLineBuilder setBindMounts(Map<Path, Path> bindMounts) {
+      this.bindMounts = Optional.of(bindMounts);
+      return this;
+    }
+
+    /** Sets the path for writing execution statistics (e.g. resource usage). */
+    public CommandLineBuilder setStatisticsPath(String statisticsPath) {
+      this.statisticsPath = Optional.of(statisticsPath);
+      return this;
+    }
+
+    /** Sets whether to use a fake 'localhost' hostname inside the sandbox. */
+    public CommandLineBuilder setUseFakeHostname(boolean useFakeHostname) {
+      this.useFakeHostname = useFakeHostname;
+      return this;
+    }
+
+    /** Sets whether to create a new network namespace. */
+    public CommandLineBuilder setCreateNetworkNamespace(boolean createNetworkNamespace) {
+      this.createNetworkNamespace = createNetworkNamespace;
+      return this;
+    }
+
+    /** Sets whether to pretend to be 'root' inside the namespace. */
+    public CommandLineBuilder setUseFakeRoot(boolean useFakeRoot) {
+      this.useFakeRoot = useFakeRoot;
+      return this;
+    }
+
+    /** Sets whether to use a fake 'nobody' username inside the sandbox. */
+    public CommandLineBuilder setUseFakeUsername(boolean useFakeUsername) {
+      this.useFakeUsername = useFakeUsername;
+      return this;
+    }
+
+    /** Sets whether to enable debug mode (e.g. to print debugging messages). */
+    public CommandLineBuilder setUseDebugMode(boolean useDebugMode) {
+      this.useDebugMode = useDebugMode;
+      return this;
+    }
+
+    /** Sets the command (and its arguments) to run using the {@code linux-sandbox} tool. */
+    public CommandLineBuilder setCommandArguments(Collection<String> commandArguments) {
+      this.commandArguments = Optional.of(commandArguments);
+      return this;
+    }
+
+    /**
+     * Builds the command line to invoke a specific command using the {@code linux-sandbox} tool.
+     */
+    public List<String> build() {
+      Preconditions.checkState(this.linuxSandboxPath.isPresent(), "linuxSandboxPath is required");
+      Preconditions.checkState(this.commandArguments.isPresent(), "commandArguments are required");
+      Preconditions.checkState(
+          !(this.useFakeUsername && this.useFakeRoot),
+          "useFakeUsername and useFakeRoot are exclusive");
+
+      ImmutableList.Builder<String> commandLineBuilder = ImmutableList.<String>builder();
+
+      commandLineBuilder.add(linuxSandboxPath.get());
+      if (workingDirectory.isPresent()) {
+        commandLineBuilder.add("-W", workingDirectory.get());
+      }
+      if (timeout.isPresent()) {
+        commandLineBuilder.add("-T", Long.toString(timeout.get().getSeconds()));
+      }
+      if (killDelay.isPresent()) {
+        commandLineBuilder.add("-t", Long.toString(killDelay.get().getSeconds()));
+      }
+      if (stdoutPath.isPresent()) {
+        commandLineBuilder.add("-l", stdoutPath.get());
+      }
+      if (stderrPath.isPresent()) {
+        commandLineBuilder.add("-L", stderrPath.get());
+      }
+      if (writableFilesAndDirectories.isPresent()) {
+        for (Path writablePath : writableFilesAndDirectories.get()) {
+          commandLineBuilder.add("-w", writablePath.getPathString());
+        }
+      }
+      if (tmpfsDirectories.isPresent()) {
+        for (Path tmpfsPath : tmpfsDirectories.get()) {
+          commandLineBuilder.add("-e", tmpfsPath.getPathString());
+        }
+      }
+      if (bindMounts.isPresent()) {
+        for (Path bindMountTarget : bindMounts.get().keySet()) {
+          Path bindMountSource = bindMounts.get().get(bindMountTarget);
+          commandLineBuilder.add("-M", bindMountSource.getPathString());
+          // The file is mounted in a custom location inside the sandbox.
+          if (!bindMountSource.equals(bindMountTarget)) {
+            commandLineBuilder.add("-m", bindMountTarget.getPathString());
+          }
+        }
+      }
+      if (statisticsPath.isPresent()) {
+        commandLineBuilder.add("-S", statisticsPath.get());
+      }
+      if (useFakeHostname) {
+        commandLineBuilder.add("-H");
+      }
+      if (createNetworkNamespace) {
+        commandLineBuilder.add("-N");
+      }
+      if (useFakeRoot) {
+        commandLineBuilder.add("-R");
+      }
+      if (useFakeUsername) {
+        commandLineBuilder.add("-U");
+      }
+      if (useDebugMode) {
+        commandLineBuilder.add("-D");
+      }
+      commandLineBuilder.add("--");
+      commandLineBuilder.addAll(commandArguments.get());
+
+      return commandLineBuilder.build();
+    }
+
+    /**
+     * Builds the command line to invoke a specific command using the {@code linux-sandbox} tool.
+     *
+     * @return the command line as an array of strings
+     */
+    public String[] buildAsArray() {
+      return build().toArray(new String[0]);
+    }
+  }
+}
diff --git a/src/main/java/com/google/devtools/build/lib/sandbox/LinuxSandboxedSpawnRunner.java b/src/main/java/com/google/devtools/build/lib/sandbox/LinuxSandboxedSpawnRunner.java
index a16497febc..674966dde3 100644
--- a/src/main/java/com/google/devtools/build/lib/sandbox/LinuxSandboxedSpawnRunner.java
+++ b/src/main/java/com/google/devtools/build/lib/sandbox/LinuxSandboxedSpawnRunner.java
@@ -14,6 +14,7 @@
 
 package com.google.devtools.build.lib.sandbox;
 
+import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Maps;
@@ -27,6 +28,7 @@ import com.google.devtools.build.lib.actions.UserExecException;
 import com.google.devtools.build.lib.analysis.BlazeDirectories;
 import com.google.devtools.build.lib.exec.local.LocalEnvProvider;
 import com.google.devtools.build.lib.runtime.CommandEnvironment;
+import com.google.devtools.build.lib.runtime.LinuxSandboxUtil;
 import com.google.devtools.build.lib.shell.Command;
 import com.google.devtools.build.lib.shell.CommandException;
 import com.google.devtools.build.lib.util.OS;
@@ -37,7 +39,6 @@ import com.google.devtools.build.lib.vfs.Symlinks;
 import java.io.File;
 import java.io.IOException;
 import java.time.Duration;
-import java.util.ArrayList;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
@@ -45,30 +46,25 @@ import java.util.SortedMap;
 
 /** Spawn runner that uses linux sandboxing APIs to execute a local subprocess. */
 final class LinuxSandboxedSpawnRunner extends AbstractSandboxSpawnRunner {
-  private static final String LINUX_SANDBOX = "linux-sandbox";
 
   public static boolean isSupported(CommandEnvironment cmdEnv) {
     if (OS.getCurrent() != OS.LINUX) {
       return false;
     }
-    Path embeddedTool = getLinuxSandbox(cmdEnv);
-    if (embeddedTool == null) {
-      // The embedded tool does not exist, meaning that we don't support sandboxing (e.g., while
-      // bootstrapping).
+    if (!LinuxSandboxUtil.isSupported(cmdEnv)) {
       return false;
     }
 
-    Path execRoot = cmdEnv.getExecRoot();
-
-    List<String> args = new ArrayList<>();
-    args.add(embeddedTool.getPathString());
-    args.add("--");
-    args.add("/bin/true");
-
+    List<String> linuxSandboxArgv =
+        LinuxSandboxUtil.commandLineBuilder(
+                LinuxSandboxUtil.getLinuxSandbox(cmdEnv).getPathString(),
+                ImmutableList.of("/bin/true"))
+            .build();
     ImmutableMap<String, String> env = ImmutableMap.of();
+    Path execRoot = cmdEnv.getExecRoot();
     File cwd = execRoot.getPathFile();
 
-    Command cmd = new Command(args.toArray(new String[0]), env, cwd);
+    Command cmd = new Command(linuxSandboxArgv.toArray(new String[0]), env, cwd);
     try {
       cmd.execute(ByteStreams.nullOutputStream(), ByteStreams.nullOutputStream());
     } catch (CommandException e) {
@@ -78,11 +74,6 @@ final class LinuxSandboxedSpawnRunner extends AbstractSandboxSpawnRunner {
     return true;
   }
 
-  private static Path getLinuxSandbox(CommandEnvironment cmdEnv) {
-    PathFragment execPath = cmdEnv.getBlazeWorkspace().getBinTools().getExecPath(LINUX_SANDBOX);
-    return execPath != null ? cmdEnv.getExecRoot().getRelative(execPath) : null;
-  }
-
   private final FileSystem fileSystem;
   private final BlazeDirectories blazeDirs;
   private final Path execRoot;
@@ -107,7 +98,7 @@ final class LinuxSandboxedSpawnRunner extends AbstractSandboxSpawnRunner {
     this.execRoot = cmdEnv.getExecRoot();
     this.productName = productName;
     this.allowNetwork = SandboxHelpers.shouldAllowNetwork(cmdEnv.getOptions());
-    this.linuxSandbox = getLinuxSandbox(cmdEnv);
+    this.linuxSandbox = LinuxSandboxUtil.getLinuxSandbox(cmdEnv);
     this.inaccessibleHelperFile = inaccessibleHelperFile;
     this.inaccessibleHelperDir = inaccessibleHelperDir;
     this.timeoutGraceSeconds = timeoutGraceSeconds;
@@ -162,67 +153,26 @@ final class LinuxSandboxedSpawnRunner extends AbstractSandboxSpawnRunner {
       Map<Path, Path> bindMounts,
       boolean allowNetwork,
       boolean requiresFakeRoot) {
-    List<String> commandLineArgs = new ArrayList<>();
-    commandLineArgs.add(linuxSandbox.getPathString());
-
-    if (getSandboxOptions().sandboxDebug) {
-      commandLineArgs.add("-D");
-    }
-
-    // Kill the process after a timeout.
+    LinuxSandboxUtil.CommandLineBuilder commandLineBuilder =
+        LinuxSandboxUtil.commandLineBuilder(linuxSandbox.getPathString(), spawn.getArguments())
+            .setWritableFilesAndDirectories(writableDirs)
+            .setTmpfsDirectories(tmpfsPaths)
+            .setBindMounts(bindMounts)
+            .setUseFakeHostname(getSandboxOptions().sandboxFakeHostname)
+            .setCreateNetworkNamespace(!allowNetwork)
+            .setUseDebugMode(getSandboxOptions().sandboxDebug);
     if (!timeout.isZero()) {
-      commandLineArgs.add("-T");
-      commandLineArgs.add(Long.toString(timeout.getSeconds()));
+      commandLineBuilder.setTimeout(timeout);
     }
-
     if (timeoutGraceSeconds != -1) {
-      commandLineArgs.add("-t");
-      commandLineArgs.add(Integer.toString(timeoutGraceSeconds));
-    }
-
-    // Create all needed directories.
-    for (Path writablePath : writableDirs) {
-      commandLineArgs.add("-w");
-      commandLineArgs.add(writablePath.getPathString());
+      commandLineBuilder.setKillDelay(Duration.ofSeconds(timeoutGraceSeconds));
     }
-
-    for (Path tmpfsPath : tmpfsPaths) {
-      commandLineArgs.add("-e");
-      commandLineArgs.add(tmpfsPath.getPathString());
-    }
-
-    for (ImmutableMap.Entry<Path, Path> bindMount : bindMounts.entrySet()) {
-      commandLineArgs.add("-M");
-      commandLineArgs.add(bindMount.getValue().getPathString());
-
-      // The file is mounted in a custom location inside the sandbox.
-      if (!bindMount.getKey().equals(bindMount.getValue())) {
-        commandLineArgs.add("-m");
-        commandLineArgs.add(bindMount.getKey().getPathString());
-      }
-    }
-
-    if (!allowNetwork) {
-      // Block network access out of the namespace.
-      commandLineArgs.add("-N");
-    }
-
-    if (getSandboxOptions().sandboxFakeHostname) {
-      // Use a fake hostname ("localhost") inside the sandbox.
-      commandLineArgs.add("-H");
-    }
-
     if (requiresFakeRoot) {
-      // Use fake root.
-      commandLineArgs.add("-R");
+      commandLineBuilder.setUseFakeRoot(true);
     } else if (getSandboxOptions().sandboxFakeUsername) {
-      // Use a fake username ("nobody") inside the sandbox.
-      commandLineArgs.add("-U");
+      commandLineBuilder.setUseFakeUsername(true);
     }
-
-    commandLineArgs.add("--");
-    commandLineArgs.addAll(spawn.getArguments());
-    return commandLineArgs;
+    return commandLineBuilder.build();
   }
 
   @Override