BlazeOptionHandler: only check in the parent directory, if there is one

When checking for a file called DO_NOT_BUILD_HERE in the parent direcotry of the
workspace path, first verify that there is such a parent directory. This avoids
a null pointer exception if the WORKSPACE file is in the top-level directory.

Fixes #5349

Change-Id: I81289a27a3f7fb0f4b5a112343de1b454fb5b8c5
PiperOrigin-RevId: 199790735

1 files changed, 13 insertions, 11 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/runtime/BlazeOptionHandler.java b/src/main/java/com/google/devtools/build/lib/runtime/BlazeOptionHandler.java
index 81a6f03f08..107cf4518d 100644
--- a/src/main/java/com/google/devtools/build/lib/runtime/BlazeOptionHandler.java
+++ b/src/main/java/com/google/devtools/build/lib/runtime/BlazeOptionHandler.java
@@ -144,17 +144,19 @@ public abstract class BlazeOptionHandler {
       return ExitCode.LOCAL_ENVIRONMENTAL_ERROR;
     }
 
-    Path doNotBuild =
-        workspacePath.getParentDirectory().getRelative(BlazeWorkspace.DO_NOT_BUILD_FILE_NAME);
-
-    if (doNotBuild.exists()) {
-      if (!commandAnnotation.canRunInOutputDirectory()) {
-        eventHandler.handle(Event.error(getNotInRealWorkspaceError(doNotBuild)));
-        return ExitCode.COMMAND_LINE_ERROR;
-      } else {
-        eventHandler.handle(
-            Event.warn(
-                runtime.getProductName() + " is run from output directory. This is unsound."));
+    if (workspacePath.getParentDirectory() != null) {
+      Path doNotBuild =
+          workspacePath.getParentDirectory().getRelative(BlazeWorkspace.DO_NOT_BUILD_FILE_NAME);
+
+      if (doNotBuild.exists()) {
+        if (!commandAnnotation.canRunInOutputDirectory()) {
+          eventHandler.handle(Event.error(getNotInRealWorkspaceError(doNotBuild)));
+          return ExitCode.COMMAND_LINE_ERROR;
+        } else {
+          eventHandler.handle(
+              Event.warn(
+                  runtime.getProductName() + " is run from output directory. This is unsound."));
+        }
       }
     }
     return ExitCode.SUCCESS;