Fix crash when calling set-webview-implementation with no argument

Fix a crash caused by a NPE when calling set-webview-implementation
without providing a package as a parameter

Bug: b/112181942
Test: manually checked that calling set-webview-implementation no longer
triggers a crash
Change-Id: Iba7c6e143d2cc78074f34ed751533287fe952ff9

1 files changed, 13 insertions, 2 deletions

diff --git a/services/core/java/com/android/server/webkit/WebViewUpdateServiceShellCommand.java b/services/core/java/com/android/server/webkit/WebViewUpdateServiceShellCommand.java
index 39e28c74e0a5..3199ed47503e 100644
--- a/services/core/java/com/android/server/webkit/WebViewUpdateServiceShellCommand.java
+++ b/services/core/java/com/android/server/webkit/WebViewUpdateServiceShellCommand.java
@@ -66,6 +66,12 @@ class WebViewUpdateServiceShellCommand extends ShellCommand {
     private int setWebViewImplementation() throws RemoteException {
         final PrintWriter pw = getOutPrintWriter();
         String shellChosenPackage = getNextArg();
+        if (shellChosenPackage == null) {
+            pw.println("Failed to switch, no PACKAGE provided.");
+            pw.println("");
+            helpSetWebViewImplementation();
+            return 1;
+        }
         String newPackage = mInterface.changeProviderAndSetting(shellChosenPackage);
         if (shellChosenPackage.equals(newPackage)) {
             pw.println("Success");
@@ -85,6 +91,12 @@ class WebViewUpdateServiceShellCommand extends ShellCommand {
         return 0;
     }
 
+    public void helpSetWebViewImplementation() {
+        PrintWriter pw = getOutPrintWriter();
+        pw.println("  set-webview-implementation PACKAGE");
+        pw.println("    Set the WebView implementation to the specified package.");
+    }
+
     @Override
     public void onHelp() {
         PrintWriter pw = getOutPrintWriter();
@@ -99,8 +111,7 @@ class WebViewUpdateServiceShellCommand extends ShellCommand {
         pw.println("  disable-redundant-packages");
         pw.println("    Disallow installing and enabling fallback packages when a more-preferred");
         pw.println("    package is available.");
-        pw.println("  set-webview-implementation PACKAGE");
-        pw.println("    Set the WebView implementation to the specified package.");
+        helpSetWebViewImplementation();
         pw.println("  enable-multiprocess");
         pw.println("    Enable multi-process mode for WebView");
         pw.println("  disable-multiprocess");