Print interactive debug instructions in HardlinkedSandboxedSpawn

src/main/java/com/google/devtools/build/lib/sandbox/HardlinkedSandboxedSpawn.java

@@ -20,12 +20,15 @@
 import com.google.devtools.build.lib.exec.TreeDeleter;
 import com.google.devtools.build.lib.sandbox.SandboxHelpers.SandboxInputs;
 import com.google.devtools.build.lib.sandbox.SandboxHelpers.SandboxOutputs;
-import com.google.devtools.build.lib.vfs.FileStatus;
+import com.google.devtools.build.lib.util.CommandDescriptionForm;
+import com.google.devtools.build.lib.util.CommandFailureUtils;
 import com.google.devtools.build.lib.vfs.FileSystemUtils;
+import com.google.devtools.build.lib.vfs.FileStatus;
 import com.google.devtools.build.lib.vfs.Path;
 import com.google.devtools.build.lib.vfs.Symlinks;
 import java.io.IOException;
 import java.util.Collection;
+import java.util.Optional;
 import java.util.Set;
 import javax.annotation.Nullable;
 
@@ -36,6 +39,8 @@
 public class HardlinkedSandboxedSpawn extends AbstractContainerizingSandboxedSpawn {
   private static final GoogleLogger logger = GoogleLogger.forEnclosingClass();
   private boolean sandboxDebug = false;
+  @Nullable private final ImmutableList<String> interactiveDebugArguments;
+
 
   public HardlinkedSandboxedSpawn(
       Path sandboxPath,
@@ -49,6 +54,7 @@ public HardlinkedSandboxedSpawn(
       @Nullable Path sandboxDebugPath,
       @Nullable Path statisticsPath,
       boolean sandboxDebug,
+      @Nullable ImmutableList<String> interactiveDebugArguments,
       String mnemonic) {
     super(
         sandboxPath,
@@ -63,6 +69,7 @@ public HardlinkedSandboxedSpawn(
         statisticsPath,
         mnemonic);
     this.sandboxDebug = sandboxDebug;
+    this.interactiveDebugArguments = interactiveDebugArguments;
   }
 
   @Override
@@ -106,4 +113,24 @@ private void hardLinkRecursive(Path source, Path target) throws IOException {
       }
     }
   }
+
+  @Nullable
+  @Override
+  public Optional<String> getInteractiveDebugInstructions() {
+    if (interactiveDebugArguments == null) {
+      return Optional.empty();
+    }
+    return Optional.of(
+        "Run this command to start an interactive shell in an identical sandboxed environment:\n"
+            + CommandFailureUtils.describeCommand(
+                CommandDescriptionForm.COMPLETE,
+                /* prettyPrintArgs= */ false,
+                interactiveDebugArguments,
+                getEnvironment(),
+                /* environmentVariablesToClear= */ null,
+                /* cwd= */ sandboxExecRoot.getPathString(),
+                /* configurationChecksum= */ null,
+                /* executionPlatformLabel= */ null,
+                /* spawnRunner= */ null));
+  }
 }

src/main/java/com/google/devtools/build/lib/sandbox/LinuxSandboxedSpawnRunner.java

@@ -354,6 +354,7 @@ protected SandboxedSpawn prepareSpawn(Spawn spawn, SpawnExecutionContext context
           sandboxDebugPath,
           statisticsPath,
           sandboxOptions.sandboxDebug,
+          makeInteractiveDebugArguments(commandLineBuilder, sandboxOptions),
           spawn.getMnemonic());
     } else {
       return new SymlinkedSandboxedSpawn(