Save encrypted logs to disk on debug builds.

briar-android/src/main/java/org/briarproject/bramble/account/BriarAccountManager.java

@@ -3,9 +3,11 @@ package org.briarproject.bramble.account;
 import android.app.Application;
 import android.content.SharedPreferences;
 
+import org.briarproject.bramble.api.FeatureFlags;
 import org.briarproject.bramble.api.crypto.CryptoComponent;
 import org.briarproject.bramble.api.db.DatabaseConfig;
 import org.briarproject.bramble.api.identity.IdentityManager;
+import org.briarproject.bramble.api.logging.PersistentLogManager;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.Localizer;
 import org.briarproject.briar.android.util.UiUtils;
@@ -15,10 +17,16 @@ import javax.inject.Inject;
 class BriarAccountManager extends AndroidAccountManager {
 
 	@Inject
-	BriarAccountManager(DatabaseConfig databaseConfig, CryptoComponent crypto,
-			IdentityManager identityManager, SharedPreferences prefs,
+	BriarAccountManager(
+			DatabaseConfig databaseConfig,
+			CryptoComponent crypto,
+			IdentityManager identityManager,
+			SharedPreferences prefs,
+			PersistentLogManager logManager,
+			FeatureFlags featureFlags,
 			Application app) {
-		super(databaseConfig, crypto, identityManager, prefs, app);
+		super(databaseConfig, crypto, identityManager, prefs, logManager,
+				featureFlags, app);
 	}
 
 	@Override

briar-android/src/main/java/org/briarproject/briar/android/AndroidComponent.java

@@ -22,6 +22,7 @@ import org.briarproject.bramble.api.keyagreement.PayloadEncoder;
 import org.briarproject.bramble.api.keyagreement.PayloadParser;
 import org.briarproject.bramble.api.lifecycle.IoExecutor;
 import org.briarproject.bramble.api.lifecycle.LifecycleManager;
+import org.briarproject.bramble.api.logging.PersistentLogManager;
 import org.briarproject.bramble.api.plugin.PluginManager;
 import org.briarproject.bramble.api.settings.SettingsManager;
 import org.briarproject.bramble.api.system.AndroidExecutor;
@@ -78,6 +79,7 @@ import org.briarproject.briar.api.privategroup.invitation.GroupInvitationManager
 import org.briarproject.briar.api.test.TestDataCreator;
 
 import java.util.concurrent.Executor;
+import java.util.logging.Formatter;
 
 import javax.inject.Singleton;
 
@@ -204,6 +206,10 @@ public interface AndroidComponent
 
 	AutoDeleteManager autoDeleteManager();
 
+	PersistentLogManager persistentLogManager();
+
+	Formatter formatter();
+
 	void inject(SignInReminderReceiver briarService);
 
 	void inject(BriarService briarService);

briar-android/src/main/java/org/briarproject/briar/android/AppModule.java

@@ -245,8 +245,9 @@ public class AppModule {
 			}
 
 			@Override
-			public File getLogcatFile() {
-				return AndroidUtils.getLogcatFile(app.getApplicationContext());
+			public File getTemporaryLogFile() {
+				return AndroidUtils
+						.getTemporaryLogFile(app.getApplicationContext());
 			}
 		};
 		return devConfig;
@@ -337,6 +338,11 @@ public class AppModule {
 			public boolean shouldEnableDisappearingMessages() {
 				return true;
 			}
+
+			@Override
+			public boolean shouldEnablePersistentLogs() {
+				return IS_DEBUG_BUILD;
+			}
 		};
 	}
 }

briar-android/src/main/java/org/briarproject/briar/android/BriarApplicationImpl.java

@@ -17,11 +17,14 @@ import com.vanniktech.emoji.google.GoogleEmojiProvider;
 import org.briarproject.bramble.BrambleAndroidEagerSingletons;
 import org.briarproject.bramble.BrambleAppComponent;
 import org.briarproject.bramble.BrambleCoreEagerSingletons;
+import org.briarproject.bramble.api.logging.PersistentLogManager;
 import org.briarproject.briar.BriarCoreEagerSingletons;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.logging.CachingLogHandler;
 import org.briarproject.briar.android.util.UiUtils;
 
+import java.io.File;
+import java.io.IOException;
 import java.lang.Thread.UncaughtExceptionHandler;
 import java.util.logging.Handler;
 import java.util.logging.Logger;
@@ -31,7 +34,10 @@ import androidx.annotation.NonNull;
 import static android.app.ActivityManager.RunningAppProcessInfo.IMPORTANCE_FOREGROUND;
 import static java.util.logging.Level.FINE;
 import static java.util.logging.Level.INFO;
+import static java.util.logging.Level.WARNING;
 import static java.util.logging.Logger.getLogger;
+import static org.briarproject.bramble.util.AndroidUtils.getPersistentLogDir;
+import static org.briarproject.bramble.util.LogUtils.logException;
 import static org.briarproject.briar.android.TestingConstants.IS_DEBUG_BUILD;
 
 public class BriarApplicationImpl extends Application
@@ -81,6 +87,17 @@ public class BriarApplicationImpl extends Application
 		rootLogger.addHandler(logHandler);
 		rootLogger.setLevel(IS_DEBUG_BUILD ? FINE : INFO);
 
+		if (applicationComponent.featureFlags().shouldEnablePersistentLogs()) {
+			PersistentLogManager logManager =
+					applicationComponent.persistentLogManager();
+			File logDir = getPersistentLogDir(this);
+			try {
+				rootLogger.addHandler(logManager.createLogHandler(logDir));
+			} catch (IOException e) {
+				logException(LOG, WARNING, e);
+			}
+		}
+
 		LOG.info("Created");
 
 		EmojiManager.install(new GoogleEmojiProvider());

briar-android/src/main/java/org/briarproject/briar/android/logging/BriefLogFormatter.java

@@ -1,74 +0,0 @@
-package org.briarproject.briar.android.logging;
-
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-
-import java.text.DateFormat;
-import java.text.SimpleDateFormat;
-import java.util.Collection;
-import java.util.Date;
-import java.util.TimeZone;
-import java.util.logging.Formatter;
-import java.util.logging.LogRecord;
-
-import javax.annotation.concurrent.ThreadSafe;
-
-import static java.util.Locale.US;
-
-@ThreadSafe
-@NotNullByDefault
-public class BriefLogFormatter extends Formatter {
-
-	public static String formatLog(Formatter formatter,
-			Collection<LogRecord> logRecords) {
-		StringBuilder sb = new StringBuilder();
-		for (LogRecord record : logRecords) {
-			String formatted = formatter.format(record);
-			sb.append(formatted).append('\n');
-		}
-		return sb.toString();
-	}
-
-	private final Object lock = new Object();
-	private final DateFormat dateFormat; // Locking: lock
-	private final Date date; // Locking: lock
-
-	public BriefLogFormatter() {
-		synchronized (lock) {
-			dateFormat = new SimpleDateFormat("MM-dd HH:mm:ss.SSS ", US);
-			dateFormat.setTimeZone(TimeZone.getTimeZone("UTC"));
-			date = new Date();
-		}
-	}
-
-	@Override
-	public String format(LogRecord record) {
-		String dateString;
-		synchronized (lock) {
-			date.setTime(record.getMillis());
-			dateString = dateFormat.format(date);
-		}
-		StringBuilder sb = new StringBuilder(dateString);
-		sb.append(record.getLevel().getName().charAt(0)).append('/');
-		String tag = record.getLoggerName();
-		tag = tag.substring(tag.lastIndexOf('.') + 1);
-		sb.append(tag).append(": ");
-		sb.append(record.getMessage());
-		Throwable t = record.getThrown();
-		if (t != null) {
-			sb.append('\n');
-			appendThrowable(sb, t);
-		}
-		return sb.toString();
-	}
-
-	private void appendThrowable(StringBuilder sb, Throwable t) {
-		sb.append(t);
-		for (StackTraceElement e : t.getStackTrace())
-			sb.append("\n        at ").append(e);
-		Throwable cause = t.getCause();
-		if (cause != null) {
-			sb.append("\n     Caused by: ");
-			appendThrowable(sb, cause);
-		}
-	}
-}

briar-android/src/main/java/org/briarproject/briar/android/logging/LogDecrypter.java

@@ -8,8 +8,9 @@ import androidx.annotation.Nullable;
 @NotNullByDefault
 public interface LogDecrypter {
 	/**
-	 * Returns decrypted log records from {@link AndroidUtils#getLogcatFile}
-	 * or null if there was an error reading the logs.
+	 * Returns decrypted log records from
+	 * {@link AndroidUtils#getTemporaryLogFile} or null if there was an error
+	 * reading the logs.
 	 */
 	@Nullable
 	String decryptLogs(@Nullable byte[] logKey);

briar-android/src/main/java/org/briarproject/briar/android/logging/LogDecrypterImpl.java

@@ -41,7 +41,7 @@ class LogDecrypterImpl implements LogDecrypter {
 	public String decryptLogs(@Nullable byte[] logKey) {
 		if (logKey == null) return null;
 		SecretKey key = new SecretKey(logKey);
-		File logFile = devConfig.getLogcatFile();
+		File logFile = devConfig.getTemporaryLogFile();
 		try (InputStream in = new FileInputStream(logFile)) {
 			InputStream reader =
 					streamReaderFactory.createLogStreamReader(in, key);

briar-android/src/main/java/org/briarproject/briar/android/logging/LogEncrypter.java

@@ -8,7 +8,7 @@ import androidx.annotation.Nullable;
 @NotNullByDefault
 public interface LogEncrypter {
 	/**
-	 * Writes encrypted log records to {@link AndroidUtils#getLogcatFile}
+	 * Writes encrypted log records to {@link AndroidUtils#getTemporaryLogFile}
 	 * and returns the encryption key if everything went fine.
 	 */
 	@Nullable

briar-android/src/main/java/org/briarproject/briar/android/logging/LogEncrypterImpl.java

@@ -33,16 +33,19 @@ class LogEncrypterImpl implements LogEncrypter {
 
 	private final DevConfig devConfig;
 	private final CachingLogHandler logHandler;
+	private final Formatter formatter;
 	private final CryptoComponent crypto;
 	private final StreamWriterFactory streamWriterFactory;
 
 	@Inject
 	LogEncrypterImpl(DevConfig devConfig,
 			CachingLogHandler logHandler,
+			Formatter formatter,
 			CryptoComponent crypto,
 			StreamWriterFactory streamWriterFactory) {
 		this.devConfig = devConfig;
 		this.logHandler = logHandler;
+		this.formatter = formatter;
 		this.crypto = crypto;
 		this.streamWriterFactory = streamWriterFactory;
 	}
@@ -51,7 +54,7 @@ class LogEncrypterImpl implements LogEncrypter {
 	@Override
 	public byte[] encryptLogs() {
 		SecretKey logKey = crypto.generateSecretKey();
-		File logFile = devConfig.getLogcatFile();
+		File logFile = devConfig.getTemporaryLogFile();
 		try (OutputStream out = new FileOutputStream(logFile)) {
 			StreamWriter streamWriter =
 					streamWriterFactory.createLogStreamWriter(out, logKey);
@@ -67,10 +70,8 @@ class LogEncrypterImpl implements LogEncrypter {
 	}
 
 	private void writeLogString(Writer writer) throws IOException {
-		Formatter formatter = new BriefLogFormatter();
 		for (LogRecord record : logHandler.getRecentLogRecords()) {
-			String formatted = formatter.format(record);
-			writer.append(formatted).append('\n');
+			writer.append(formatter.format(record)).append('\n');
 		}
 	}
 

briar-android/src/main/java/org/briarproject/briar/android/reporting/BriarReportCollector.java

@@ -26,6 +26,7 @@ import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.briar.BuildConfig;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.reporting.ReportData.MultiReportInfo;
+import org.briarproject.briar.android.reporting.ReportData.ReportInfo;
 import org.briarproject.briar.android.reporting.ReportData.ReportItem;
 import org.briarproject.briar.android.reporting.ReportData.SingleReportInfo;
 
@@ -71,7 +72,7 @@ class BriarReportCollector {
 	}
 
 	ReportData collectReportData(@Nullable Throwable t, long appStartTime,
-			String logs) {
+			ReportInfo logs) {
 		ReportData reportData = new ReportData()
 				.add(getBasicInfo(t))
 				.add(getDeviceInfo());
@@ -82,7 +83,7 @@ class BriarReportCollector {
 				.add(getStorage())
 				.add(getConnectivity())
 				.add(getBuildConfig())
-				.add(getLogcat(logs))
+				.add(getLogs(logs))
 				.add(getDeviceFeatures());
 	}
 
@@ -309,8 +310,8 @@ class BriarReportCollector {
 				buildConfig);
 	}
 
-	private ReportItem getLogcat(String logs) {
-		return new ReportItem("Logcat", R.string.dev_report_logcat, logs);
+	private ReportItem getLogs(ReportInfo logs) {
+		return new ReportItem("Logs", R.string.dev_report_logcat, logs);
 	}
 
 	private ReportItem getDeviceFeatures() {

briar-android/src/main/java/org/briarproject/briar/android/reporting/ReportViewModel.java

@@ -4,6 +4,8 @@ import android.app.Application;
 import android.os.Handler;
 import android.os.Looper;
 
+import org.briarproject.bramble.api.FeatureFlags;
+import org.briarproject.bramble.api.logging.PersistentLogManager;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.plugin.Plugin;
 import org.briarproject.bramble.api.plugin.PluginManager;
@@ -11,7 +13,6 @@ import org.briarproject.bramble.api.plugin.TorConstants;
 import org.briarproject.bramble.api.reporting.DevReporter;
 import org.briarproject.bramble.util.AndroidUtils;
 import org.briarproject.briar.R;
-import org.briarproject.briar.android.logging.BriefLogFormatter;
 import org.briarproject.briar.android.logging.CachingLogHandler;
 import org.briarproject.briar.android.logging.LogDecrypter;
 import org.briarproject.briar.android.reporting.ReportData.MultiReportInfo;
@@ -22,6 +23,9 @@ import org.json.JSONException;
 
 import java.io.File;
 import java.io.FileNotFoundException;
+import java.io.IOException;
+import java.util.LinkedList;
+import java.util.Scanner;
 import java.util.UUID;
 import java.util.logging.Formatter;
 import java.util.logging.Logger;
@@ -39,18 +43,24 @@ import static java.util.Objects.requireNonNull;
 import static java.util.logging.Level.WARNING;
 import static java.util.logging.Logger.getLogger;
 import static org.briarproject.bramble.api.plugin.Plugin.State.ACTIVE;
+import static org.briarproject.bramble.util.AndroidUtils.getPersistentLogDir;
+import static org.briarproject.bramble.util.LogUtils.formatLog;
 import static org.briarproject.bramble.util.LogUtils.logException;
 import static org.briarproject.bramble.util.StringUtils.isNullOrEmpty;
-import static org.briarproject.briar.android.logging.BriefLogFormatter.formatLog;
 
 @NotNullByDefault
 class ReportViewModel extends AndroidViewModel {
 
+	private static final int MAX_PERSISTENT_LOG_LINES = 1000;
+
 	private static final Logger LOG =
 			getLogger(ReportViewModel.class.getName());
 
 	private final CachingLogHandler logHandler;
 	private final LogDecrypter logDecrypter;
+	private final Formatter formatter;
+	private final PersistentLogManager logManager;
+	private final FeatureFlags featureFlags;
 	private final BriarReportCollector collector;
 	private final DevReporter reporter;
 	private final PluginManager pluginManager;
@@ -71,12 +81,18 @@ class ReportViewModel extends AndroidViewModel {
 	ReportViewModel(@NonNull Application application,
 			CachingLogHandler logHandler,
 			LogDecrypter logDecrypter,
+			Formatter formatter,
+			PersistentLogManager logManager,
+			FeatureFlags featureFlags,
 			DevReporter reporter,
 			PluginManager pluginManager) {
 		super(application);
 		collector = new BriarReportCollector(application);
 		this.logHandler = logHandler;
 		this.logDecrypter = logDecrypter;
+		this.formatter = formatter;
+		this.logManager = logManager;
+		this.featureFlags = featureFlags;
 		this.reporter = reporter;
 		this.pluginManager = pluginManager;
 	}
@@ -86,22 +102,30 @@ class ReportViewModel extends AndroidViewModel {
 		this.initialComment = initialComment;
 		isFeedback = t == null;
 		if (reportData.getValue() == null) new SingleShotAndroidExecutor(() -> {
-			String decryptedLogs;
+			String currentLog;
 			if (isFeedback) {
-				Formatter formatter = new BriefLogFormatter();
-				decryptedLogs =
-						formatLog(formatter, logHandler.getRecentLogRecords());
+				// We're in the main process, so get the log for this process
+				currentLog = formatLog(formatter,
+						logHandler.getRecentLogRecords());
 			} else {
-				decryptedLogs = logDecrypter.decryptLogs(logKey);
-				if (decryptedLogs == null) {
+				// We're in the crash reporter process, so try to load
+				// the encrypted log that was saved by the main process
+				currentLog = logDecrypter.decryptLogs(logKey);
+				if (currentLog == null) {
 					// error decrypting logs, get logs from this process
-					Formatter formatter = new BriefLogFormatter();
-					decryptedLogs = formatLog(formatter,
+					currentLog = formatLog(formatter,
 							logHandler.getRecentLogRecords());
 				}
 			}
+			MultiReportInfo logs = new MultiReportInfo();
+			logs.add("Current", currentLog);
+			if (isFeedback && featureFlags.shouldEnablePersistentLogs()) {
+				// Add persistent logs for the current and previous processes
+				logs.add("Persistent", getPersistentLog(false));
+				logs.add("PersistentOld", getPersistentLog(true));
+			}
 			ReportData data =
-					collector.collectReportData(t, appStartTime, decryptedLogs);
+					collector.collectReportData(t, appStartTime, logs);
 			reportData.postValue(data);
 		}).start();
 	}
@@ -226,6 +250,27 @@ class ReportViewModel extends AndroidViewModel {
 		return closeReport;
 	}
 
+	private String getPersistentLog(boolean old) {
+		File logDir = getPersistentLogDir(getApplication());
+		StringBuilder sb = new StringBuilder();
+		try {
+			Scanner scanner = logManager.getPersistentLog(logDir, old);
+			LinkedList<String> lines = new LinkedList<>();
+			int numLines = 0;
+			while (scanner.hasNextLine()) {
+				lines.add(scanner.nextLine());
+				// If there are too many lines, return the most recent ones
+				if (numLines == MAX_PERSISTENT_LOG_LINES) lines.pollFirst();
+				else numLines++;
+			}
+			scanner.close();
+			for (String line : lines) sb.append(line).append('\n');
+		} catch (IOException e) {
+			sb.append("Could not recover persistent log: ").append(e);
+		}
+		return sb.toString();
+	}
+
 	// Used for a new thread as the Android executor thread may have died
 	private static class SingleShotAndroidExecutor extends Thread {
 

briar-android/src/main/java/org/briarproject/briar/android/settings/SettingsFragment.java

@@ -8,6 +8,7 @@ import android.view.View;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.briar.R;
+import org.briarproject.briar.android.util.ActivityLaunchers.CreateDocumentAdvanced;
 import org.briarproject.briar.android.util.ActivityLaunchers.GetImageAdvanced;
 
 import javax.inject.Inject;
@@ -37,6 +38,10 @@ public class SettingsFragment extends PreferenceFragmentCompat {
 	private static final String PREF_KEY_DEV = "pref_key_dev";
 	private static final String PREF_KEY_EXPLODE = "pref_key_explode";
 	private static final String PREF_KEY_SHARE_APP = "pref_key_share_app";
+	private static final String PREF_KEY_EXPORT_LOG = "pref_key_export_log";
+	private static final String PREF_EXPORT_OLD_LOG = "pref_key_export_old_log";
+
+	private static final String LOG_EXPORT_FILENAME = "briar-log.txt";
 
 	@Inject
 	ViewModelProvider.Factory viewModelFactory;
@@ -44,10 +49,18 @@ public class SettingsFragment extends PreferenceFragmentCompat {
 	private SettingsViewModel viewModel;
 	private AvatarPreference prefAvatar;
 
-	private final ActivityResultLauncher<String> launcher =
+	private final ActivityResultLauncher<String> imageLauncher =
 			registerForActivityResult(new GetImageAdvanced(),
 					this::onImageSelected);
 
+	private final ActivityResultLauncher<String> logLauncher =
+			registerForActivityResult(new CreateDocumentAdvanced(),
+					uri -> onLogFileSelected(false, uri));
+
+	private final ActivityResultLauncher<String> oldLogLauncher =
+			registerForActivityResult(new CreateDocumentAdvanced(),
+					uri -> onLogFileSelected(true, uri));
+
 	@Override
 	public void onAttach(@NonNull Context context) {
 		super.onAttach(context);
@@ -63,7 +76,7 @@ public class SettingsFragment extends PreferenceFragmentCompat {
 		prefAvatar = requireNonNull(findPreference(PREF_KEY_AVATAR));
 		if (viewModel.shouldEnableProfilePictures()) {
 			prefAvatar.setOnPreferenceClickListener(preference -> {
-				launcher.launch("image/*");
+				imageLauncher.launch("image/*");
 				return true;
 			});
 		} else {
@@ -77,11 +90,24 @@ public class SettingsFragment extends PreferenceFragmentCompat {
 			return true;
 		});
 
-		Preference explode = requireNonNull(findPreference(PREF_KEY_EXPLODE));
 		if (IS_DEBUG_BUILD) {
+			Preference explode =
+					requireNonNull(findPreference(PREF_KEY_EXPLODE));
 			explode.setOnPreferenceClickListener(preference -> {
 				throw new RuntimeException("Boom!");
 			});
+			Preference exportLog =
+					requireNonNull(findPreference(PREF_KEY_EXPORT_LOG));
+			exportLog.setOnPreferenceClickListener(preference -> {
+				logLauncher.launch(LOG_EXPORT_FILENAME);
+				return true;
+			});
+			Preference exportOldLog =
+					requireNonNull(findPreference(PREF_EXPORT_OLD_LOG));
+			exportOldLog.setOnPreferenceClickListener(preference -> {
+				oldLogLauncher.launch(LOG_EXPORT_FILENAME);
+				return true;
+			});
 		} else {
 			PreferenceGroup dev = requireNonNull(findPreference(PREF_KEY_DEV));
 			dev.setVisible(false);
@@ -111,4 +137,7 @@ public class SettingsFragment extends PreferenceFragmentCompat {
 				ConfirmAvatarDialogFragment.TAG);
 	}
 
+	private void onLogFileSelected(boolean old, @Nullable Uri uri) {
+		if (uri != null) viewModel.exportPersistentLog(old, uri);
+	}
 }

briar-android/src/main/java/org/briarproject/briar/android/settings/SettingsViewModel.java

@@ -16,6 +16,7 @@ import org.briarproject.bramble.api.identity.IdentityManager;
 import org.briarproject.bramble.api.identity.LocalAuthor;
 import org.briarproject.bramble.api.lifecycle.IoExecutor;
 import org.briarproject.bramble.api.lifecycle.LifecycleManager;
+import org.briarproject.bramble.api.logging.PersistentLogManager;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.bramble.api.plugin.BluetoothConstants;
@@ -35,8 +36,12 @@ import org.briarproject.briar.api.avatar.AvatarManager;
 import org.briarproject.briar.api.identity.AuthorInfo;
 import org.briarproject.briar.api.identity.AuthorManager;
 
+import java.io.File;
 import java.io.IOException;
 import java.io.InputStream;
+import java.io.OutputStream;
+import java.io.PrintWriter;
+import java.util.Scanner;
 import java.util.concurrent.Executor;
 import java.util.logging.Logger;
 
@@ -50,6 +55,7 @@ import static android.widget.Toast.LENGTH_LONG;
 import static java.util.Arrays.asList;
 import static java.util.logging.Level.WARNING;
 import static java.util.logging.Logger.getLogger;
+import static org.briarproject.bramble.util.AndroidUtils.getPersistentLogDir;
 import static org.briarproject.bramble.util.AndroidUtils.getSupportedImageContentTypes;
 import static org.briarproject.bramble.util.LogUtils.logDuration;
 import static org.briarproject.bramble.util.LogUtils.logException;
@@ -78,6 +84,7 @@ class SettingsViewModel extends DbViewModel implements EventListener {
 	private final ImageCompressor imageCompressor;
 	private final Executor ioExecutor;
 	private final FeatureFlags featureFlags;
+	private final PersistentLogManager logManager;
 
 	final SettingsStore settingsStore;
 	final TorSummaryProvider torSummaryProvider;
@@ -108,7 +115,8 @@ class SettingsViewModel extends DbViewModel implements EventListener {
 			LocationUtils locationUtils,
 			CircumventionProvider circumventionProvider,
 			@IoExecutor Executor ioExecutor,
-			FeatureFlags featureFlags) {
+			FeatureFlags featureFlags,
+			PersistentLogManager logManager) {
 		super(application, dbExecutor, lifecycleManager, db, androidExecutor);
 		this.settingsManager = settingsManager;
 		this.identityManager = identityManager;
@@ -118,6 +126,7 @@ class SettingsViewModel extends DbViewModel implements EventListener {
 		this.authorManager = authorManager;
 		this.ioExecutor = ioExecutor;
 		this.featureFlags = featureFlags;
+		this.logManager = logManager;
 		settingsStore = new SettingsStore(settingsManager, dbExecutor,
 				SETTINGS_NAMESPACE);
 		torSummaryProvider = new TorSummaryProvider(getApplication(),
@@ -262,4 +271,38 @@ class SettingsViewModel extends DbViewModel implements EventListener {
 		return screenLockTimeout;
 	}
 
+	void exportPersistentLog(boolean old, Uri uri) {
+		// We can use untranslated strings here, as this method is only called
+		// in debug builds
+		ioExecutor.execute(() -> {
+			Application app = getApplication();
+			try {
+				OutputStream os =
+						app.getContentResolver().openOutputStream(uri);
+				if (os == null) throw new IOException();
+				File logDir = getPersistentLogDir(app);
+				Scanner scanner = logManager.getPersistentLog(logDir, old);
+				if (!scanner.hasNextLine()) {
+					scanner.close();
+					androidExecutor.runOnUiThread(() ->
+							Toast.makeText(app, "Log is empty",
+									LENGTH_LONG).show());
+					return;
+				}
+				PrintWriter w = new PrintWriter(os);
+				while (scanner.hasNextLine()) w.println(scanner.nextLine());
+				w.flush();
+				w.close();
+				scanner.close();
+				androidExecutor.runOnUiThread(() ->
+						Toast.makeText(app, "Log exported",
+								LENGTH_LONG).show());
+			} catch (IOException e) {
+				logException(LOG, WARNING, e);
+				androidExecutor.runOnUiThread(() ->
+						Toast.makeText(app, "Failed to export log",
+								LENGTH_LONG).show());
+			}
+		});
+	}
 }

briar-android/src/main/res/xml/settings.xml

@@ -58,6 +58,14 @@
 				android:targetPackage="@string/app_package" />
 		</Preference>
 
+		<Preference
+			android:key="pref_key_export_log"
+			android:title="Export current log to SD card" />
+
+		<Preference
+			android:key="pref_key_export_old_log"
+			android:title="Export previous log to SD card" />
+
 		<Preference
 			android:key="pref_key_explode"
 			android:title="Crash" />

briar-android/src/test/java/org/briarproject/briar/android/logging/LogEncryptionDecryptionTest.java

@@ -1,5 +1,6 @@
 package org.briarproject.briar.android.logging;
 
+import org.briarproject.bramble.logging.BriefLogFormatter;
 import org.briarproject.bramble.test.BrambleMockTestCase;
 import org.junit.ClassRule;
 import org.junit.Test;
@@ -15,8 +16,8 @@ import static java.util.logging.Level.FINE;
 import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.SEVERE;
 import static java.util.logging.Level.WARNING;
+import static org.briarproject.bramble.util.LogUtils.formatLog;
 import static org.briarproject.bramble.util.StringUtils.getRandomString;
-import static org.briarproject.briar.android.logging.BriefLogFormatter.formatLog;
 import static org.junit.Assert.assertEquals;
 
 public class LogEncryptionDecryptionTest extends BrambleMockTestCase {

briar-android/src/test/java/org/briarproject/briar/android/logging/LoggingTestModule.java

@@ -42,7 +42,7 @@ class LoggingTestModule {
 			}
 
 			@Override
-			public File getLogcatFile() {
+			public File getTemporaryLogFile() {
 				return logFile;
 			}
 		};