Use SAF on Android >= 30, to deal with Scoped storage

3 files changed, 66 insertions, 24 deletions

diff --git a/app/build.gradle b/app/build.gradle
index 26a5865..c1198f9 100644
--- a/app/build.gradle
+++ b/app/build.gradle
@@ -137,6 +137,8 @@ dependencies {
     implementation project(":libraries:humla")
     implementation 'androidx.appcompat:appcompat:1.1.0'
     implementation 'androidx.cardview:cardview:1.0.0'
+    implementation 'androidx.documentfile:documentfile:1.0.1'
+    implementation 'androidx.fragment:fragment:1.3.4'
     implementation 'androidx.recyclerview:recyclerview:1.1.0'
     implementation 'org.jsoup:jsoup:1.13.1'
     implementation 'info.guardianproject.netcipher:netcipher:2.1.0'
diff --git a/app/src/main/AndroidManifest.xml b/app/src/main/AndroidManifest.xml
index b55176a..30b8373 100644
--- a/app/src/main/AndroidManifest.xml
+++ b/app/src/main/AndroidManifest.xml
@@ -17,7 +17,7 @@
   -->
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
     android:installLocation="auto"
-    package="se.lublin.mumla" >
+    package="se.lublin.mumla">
 
     <uses-feature
         android:name="android.hardware.microphone"
@@ -26,7 +26,9 @@
     <uses-permission android:name="android.permission.FOREGROUND_SERVICE" />
     <uses-permission android:name="android.permission.RECORD_AUDIO" />
     <uses-permission android:name="android.permission.INTERNET" />
-    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
+    <uses-permission
+        android:name="android.permission.WRITE_EXTERNAL_STORAGE"
+        android:maxSdkVersion="29" />
     <uses-permission android:name="android.permission.WAKE_LOCK" />
     <uses-permission android:name="android.permission.SYSTEM_ALERT_WINDOW" />
     <uses-permission android:name="android.permission.VIBRATE" />
@@ -45,13 +47,13 @@
         android:icon="@mipmap/ic_launcher"
         android:label="@string/app_name"
         android:theme="@style/Theme.Mumla"
-        android:requestLegacyExternalStorage="true" >
-        <!-- TODO ^^^ fix, on sdk 30, no more requestlegacyexternalstorage ! -->
+        android:requestLegacyExternalStorage="true">
+        <!-- requestLegacyExternalStorage still true: we keep using old code if Android < 30 -->
 
         <activity android:name=".wizard.WizardActivity" />
         <activity
             android:name=".preference.Preferences"
-            android:parentActivityName=".app.MumlaActivity" >
+            android:parentActivityName=".app.MumlaActivity">
             <intent-filter>
                 <action android:name="se.lublin.mumla.app.PREFS_GENERAL" />
 
diff --git a/app/src/main/java/se/lublin/mumla/preference/CertificateExportActivity.java b/app/src/main/java/se/lublin/mumla/preference/CertificateExportActivity.java
index 5dba6a6..5446e79 100644
--- a/app/src/main/java/se/lublin/mumla/preference/CertificateExportActivity.java
+++ b/app/src/main/java/se/lublin/mumla/preference/CertificateExportActivity.java
@@ -17,25 +17,33 @@
 
 package se.lublin.mumla.preference;
 
+import static android.os.Build.VERSION.SDK_INT;
+
 import android.Manifest;
 import android.content.DialogInterface;
 import android.content.pm.PackageManager;
+import android.net.Uri;
+import android.os.Build;
 import android.os.Bundle;
 import android.os.Environment;
 import android.util.Log;
 import android.widget.Toast;
 
+import androidx.activity.result.ActivityResultLauncher;
+import androidx.activity.result.contract.ActivityResultContracts.CreateDocument;
 import androidx.annotation.NonNull;
 import androidx.appcompat.app.AlertDialog;
 import androidx.appcompat.app.AppCompatActivity;
 import androidx.core.app.ActivityCompat;
 import androidx.core.content.ContextCompat;
+import androidx.documentfile.provider.DocumentFile;
 
 import java.io.BufferedOutputStream;
 import java.io.File;
 import java.io.FileNotFoundException;
 import java.io.FileOutputStream;
 import java.io.IOException;
+import java.io.OutputStream;
 import java.util.List;
 
 import se.lublin.mumla.Constants;
@@ -56,8 +64,10 @@ public class CertificateExportActivity extends AppCompatActivity implements Dial
     private MumlaDatabase mDatabase;
     private List<DatabaseCertificate> mCertificates;
 
+    private final ActivityResultLauncher<String> documentCreator =
+            registerForActivityResult(new CreateDocument(), this::onDocumentCreated);
     private static final int PERMISSIONS_REQUEST_WRITE_EXTERNAL_STORAGE = 2;
-    private DatabaseCertificate mCertificatePendingPerm = null;
+    private DatabaseCertificate mCertificatePending = null;
 
     @Override
     protected void onCreate(Bundle savedInstanceState) {
@@ -91,26 +101,46 @@ public class CertificateExportActivity extends AppCompatActivity implements Dial
     @Override
     public void onClick(DialogInterface dialog, int which) {
         DatabaseCertificate certificate = mCertificates.get(which);
-        saveCertificate(certificate);
+        if (SDK_INT >= Build.VERSION_CODES.R) {
+            // TODO Should always use this method?
+            mCertificatePending = certificate;
+            documentCreator.launch(certificate.getName());
+        } else {
+            saveCertificateClassic(certificate);
+        }
     }
 
-    private void saveCertificate(DatabaseCertificate certificate) {
+    private void onDocumentCreated(Uri uri) {
+        if (uri != null && mCertificatePending != null) {
+            try {
+                OutputStream os = getContentResolver().openOutputStream(uri);
+                DocumentFile df = DocumentFile.fromSingleUri(this, uri);
+                writeCertificate(os, mCertificatePending, df != null ? df.getName() : "<unknown>");
+            } catch (FileNotFoundException e) {
+                showErrorDialog(R.string.externalStorageUnavailable);
+                Log.w(Constants.TAG, "FileNotFound on output file picked by user?!");
+            }
+        } else if (mCertificatePending == null) {
+            Log.w(Constants.TAG, "No pending certificate after user picked output file");
+        }
+        finish();
+    }
+
+    private void saveCertificateClassic(DatabaseCertificate certificate) {
         if (ContextCompat.checkSelfPermission(CertificateExportActivity.this,
                 Manifest.permission.WRITE_EXTERNAL_STORAGE)
                 != PackageManager.PERMISSION_GRANTED) {
             ActivityCompat.requestPermissions(CertificateExportActivity.this,
                     new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE},
                     PERMISSIONS_REQUEST_WRITE_EXTERNAL_STORAGE);
-            mCertificatePendingPerm = certificate;
+            mCertificatePending = certificate;
             return;
         }
 
-        byte[] data = mDatabase.getCertificateData(certificate.getId());
         if (!Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {
             showErrorDialog(R.string.externalStorageUnavailable);
             return;
         }
-
         File storageDirectory = Environment.getExternalStorageDirectory();
         File mumlaDirectory = new File(storageDirectory, EXTERNAL_STORAGE_DIR);
         if (!mumlaDirectory.exists() && !mumlaDirectory.mkdir()) {
@@ -118,20 +148,15 @@ public class CertificateExportActivity extends AppCompatActivity implements Dial
             return;
         }
         File outputFile = new File(mumlaDirectory, certificate.getName());
+        FileOutputStream fos;
         try {
-            FileOutputStream fos = new FileOutputStream(outputFile);
-            BufferedOutputStream bos = new BufferedOutputStream(fos);
-            bos.write(data);
-            bos.close();
-
-            Toast.makeText(this, getString(R.string.export_success, outputFile.getAbsolutePath()), Toast.LENGTH_LONG).show();
-            finish();
+            fos = new FileOutputStream(outputFile);
         } catch (FileNotFoundException e) {
             showErrorDialog(R.string.externalStorageUnavailable);
-        } catch (IOException e) {
-            e.printStackTrace();
-            showErrorDialog(R.string.error_writing_to_storage);
+            return;
         }
+        writeCertificate(fos, certificate, outputFile.getAbsolutePath());
+        finish();
     }
 
     @Override
@@ -140,8 +165,8 @@ public class CertificateExportActivity extends AppCompatActivity implements Dial
         super.onRequestPermissionsResult(requestCode, permissions, grantResults);
         if (requestCode == PERMISSIONS_REQUEST_WRITE_EXTERNAL_STORAGE) {
             if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
-                if (mCertificatePendingPerm != null) {
-                    saveCertificate(mCertificatePendingPerm);
+                if (mCertificatePending != null) {
+                    saveCertificateClassic(mCertificatePending);
                 } else {
                     Log.w(Constants.TAG, "No pending certificate after permission was granted");
                 }
@@ -149,7 +174,20 @@ public class CertificateExportActivity extends AppCompatActivity implements Dial
                 Toast.makeText(CertificateExportActivity.this, getString(R.string.grant_perm_storage),
                         Toast.LENGTH_LONG).show();
             }
-            mCertificatePendingPerm = null;
+            mCertificatePending = null;
+        }
+    }
+
+    private void writeCertificate(OutputStream fos, DatabaseCertificate cert, String path) {
+        byte[] data = mDatabase.getCertificateData(cert.getId());
+        try {
+            BufferedOutputStream bos = new BufferedOutputStream(fos);
+            bos.write(data);
+            bos.close();
+            Toast.makeText(this, getString(R.string.export_success, path), Toast.LENGTH_LONG).show();
+        } catch (IOException e) {
+            e.printStackTrace();
+            showErrorDialog(R.string.error_writing_to_storage);
         }
     }