(#) Using the result of check permission calls !!! WARNING: Using the result of check permission calls This is a warning. Id : `UseCheckPermission` Summary : Using the result of check permission calls Severity : Warning Category : Security Platform : Android Vendor : Android Open Source Project Feedback : https://issuetracker.google.com/issues/new?component=192708 Since : 3.6.0 (February 2020) Affects : Kotlin and Java files and test sources Editing : This check runs on the fly in the IDE editor Implementation : [Source Code](https://cs.android.com/android-studio/platform/tools/base/+/mirror-goog-studio-main:lint/libs/lint-checks/src/main/java/com/android/tools/lint/checks/CheckResultDetector.kt) Tests : [Source Code](https://cs.android.com/android-studio/platform/tools/base/+/mirror-goog-studio-main:lint/libs/lint-tests/src/test/java/com/android/tools/lint/checks/CheckResultDetectorTest.kt) You normally want to use the result of checking a permission; these methods return whether the permission is held; they do not throw an error if the permission is not granted. Code which does not do anything with the return value probably meant to be calling the enforce methods instead, e.g. rather than `Context#checkCallingPermission` it should call `Context#enforceCallingPermission`. !!! Tip This lint check has an associated quickfix available in the IDE. (##) Example Here is an example of lint warnings produced by this check: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~text src/test/pkg/CheckPermissions.java:10:Warning: The result of checkCallingOrSelfPermission is not used; did you mean to call #enforceCallingOrSelfPermission(String,String)? [UseCheckPermission] context.checkCallingOrSelfPermission(Manifest.permission.INTERNET); // WRONG ------------------------------------------------------------------ src/test/pkg/CheckPermissions.java:11:Warning: The result of checkPermission is not used; did you mean to call #enforcePermission(String,int,int,String)? [UseCheckPermission] context.checkPermission(Manifest.permission.INTERNET, 1, 1); ----------------------------------------------------------- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Here are the relevant source files: `src/test/pkg/CheckPermissions.java`: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~java linenumbers package test.pkg; import android.Manifest; import android.content.Context; import android.content.pm.PackageManager; import android.graphics.Bitmap; @SuppressWarnings("ClassNameDiffersFromFileName") public class CheckPermissions { private void foo(Context context) { context.checkCallingOrSelfPermission(Manifest.permission.INTERNET); // WRONG context.checkPermission(Manifest.permission.INTERNET, 1, 1); check(context.checkCallingOrSelfPermission(Manifest.permission.INTERNET)); // OK int check = context.checkCallingOrSelfPermission(Manifest.permission.INTERNET); // OK if (context.checkCallingOrSelfPermission(Manifest.permission.INTERNET) // OK != PackageManager.PERMISSION_GRANTED) { showAlert(context, "Error", "Application requires permission to access the Internet"); } } private Bitmap checkResult(Bitmap bitmap) { bitmap.extractAlpha(); // WARNING Bitmap bitmap2 = bitmap.extractAlpha(); // OK call(bitmap.extractAlpha()); // OK return bitmap.extractAlpha(); // OK } private void showAlert(Context context, String error, String s) { } private void check(int i) { } private void call(Bitmap bitmap) { } } ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ `src/test/pkg/Intersect.java`: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~java linenumbers package test.pkg; import android.graphics.Rect; @SuppressWarnings({"ClassNameDiffersFromFileName", "MethodMayBeStatic"}) public class Intersect { void check(Rect rect, int aLeft, int aTop, int aRight, int aBottom) { rect.intersect(aLeft, aTop, aRight, aBottom); } } ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ You can also visit the [source code](https://cs.android.com/android-studio/platform/tools/base/+/mirror-goog-studio-main:lint/libs/lint-tests/src/test/java/com/android/tools/lint/checks/CheckResultDetectorTest.kt) for the unit tests for this check to see additional scenarios. The above example was automatically extracted from the first unit test found for this lint check, `CheckResultDetector.testCheckResult`. To report a problem with this extracted sample, visit https://issuetracker.google.com/issues/new?component=192708. (##) Suppressing You can suppress false positives using one of the following mechanisms: * Using a suppression annotation like this on the enclosing element: ```kt // Kotlin @Suppress("UseCheckPermission") fun method() { problematicStatement() } ``` or ```java // Java @SuppressWarnings("UseCheckPermission") void method() { problematicStatement(); } ``` * Using a suppression comment like this on the line above: ```kt //noinspection UseCheckPermission problematicStatement() ``` * Using a special `lint.xml` file in the source tree which turns off the check in that folder and any sub folder. A simple file might look like this: ```xml <?xml version="1.0" encoding="UTF-8"?> <lint> <issue id="UseCheckPermission" severity="ignore" /> </lint> ``` Instead of `ignore` you can also change the severity here, for example from `error` to `warning`. You can find additional documentation on how to filter issues by path, regular expression and so on [here](https://googlesamples.github.io/android-custom-lint-rules/usage/lintxml.md.html). * In Gradle projects, using the DSL syntax to configure lint. For example, you can use something like ```gradle lintOptions { disable 'UseCheckPermission' } ``` In Android projects this should be nested inside an `android { }` block. * For manual invocations of `lint`, using the `--ignore` flag: ``` $ lint --ignore UseCheckPermission ...` ``` * Last, but not least, using baselines, as discussed [here](https://googlesamples.github.io/android-custom-lint-rules/usage/baselines.md.html).