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

src/main/java/com/google/devtools/build/lib/packages/Package.java

diff --git a/src/main/java/com/google/devtools/build/lib/packages/Package.java b/src/main/java/com/google/devtools/build/lib/packages/Package.java
index 1ea31a1..d6f7944 100644
--- a/src/main/java/com/google/devtools/build/lib/packages/Package.java
+++ b/src/main/java/com/google/devtools/build/lib/packages/Package.java
@@ -340,7 +340,9 @@
     Path current = buildFile.getParentDirectory();
     for (int i = 0, len = packageFragment.segmentCount();
          i < len && !packageFragment.equals(PathFragment.EMPTY_FRAGMENT); i++) {
-      current = current.getParentDirectory();
+      if (current != null) {
+        current = current.getParentDirectory();
+      }
     }
     return Root.fromPath(current);
   }
@@ -367,8 +369,8 @@
     this.packageDirectory = filename.getParentDirectory();
 
     this.sourceRoot = getSourceRoot(filename, packageIdentifier.getSourceRoot());
-    if ((sourceRoot == null
-        || !sourceRoot.getRelative(packageIdentifier.getSourceRoot()).equals(packageDirectory))
+    if ((sourceRoot.asPath() == null
+            || !sourceRoot.getRelative(packageIdentifier.getSourceRoot()).equals(packageDirectory))
         && !filename.getBaseName().equals("WORKSPACE")) {
       throw new IllegalArgumentException(
           "Invalid BUILD file name for package '" + packageIdentifier + "': " + filename);

src/main/java/com/google/devtools/build/lib/runtime/BlazeOptionHandler.java

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 81a6f03..107cf45 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 @@
       return ExitCode.LOCAL_ENVIRONMENTAL_ERROR;
     }
 
-    Path doNotBuild =
-        workspacePath.getParentDirectory().getRelative(BlazeWorkspace.DO_NOT_BUILD_FILE_NAME);
+    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."));
+      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;