Feature: Mount Provider

pom.xml

@@ -59,13 +59,13 @@
 		<dependency>
 			<groupId>org.junit.jupiter</groupId>
 			<artifactId>junit-jupiter</artifactId>
-			<version>5.8.2</version>
+			<version>5.9.0</version>
 			<scope>test</scope>
 		</dependency>
 		<dependency>
 			<groupId>org.mockito</groupId>
 			<artifactId>mockito-core</artifactId>
-			<version>4.3.1</version>
+			<version>4.8.0</version>
 			<scope>test</scope>
 		</dependency>
 	</dependencies>

src/main/java/module-info.java

@@ -1,3 +1,4 @@
+import org.cryptomator.integrations.mount.MountProvider;
 import org.cryptomator.integrations.tray.TrayMenuController;
 import org.cryptomator.integrations.autostart.AutoStartProvider;
 import org.cryptomator.integrations.keychain.KeychainAccessProvider;
@@ -12,11 +13,13 @@
 	exports org.cryptomator.integrations.autostart;
 	exports org.cryptomator.integrations.common;
 	exports org.cryptomator.integrations.keychain;
+	exports org.cryptomator.integrations.mount;
 	exports org.cryptomator.integrations.tray;
 	exports org.cryptomator.integrations.uiappearance;
 
 	uses AutoStartProvider;
 	uses KeychainAccessProvider;
+	uses MountProvider;
 	uses TrayIntegrationProvider;
 	uses TrayMenuController;
 	uses UiAppearanceProvider;

src/main/java/org/cryptomator/integrations/mount/Mount.java

@@ -0,0 +1,44 @@
+package org.cryptomator.integrations.mount;
+
+import java.nio.file.Path;
+
+/**
+ * Handle to control the lifecycle of a mounted file system.
+ * <p>
+ * Created by {@link MountBuilder}
+ */
+public interface Mount extends AutoCloseable {
+
+	/**
+	 * Returns the absolute OS path, where this mount can be accessed.
+	 *
+	 * @return Absolute path to the mountpoint.
+	 */
+	Path getMountpoint();
+
+	/**
+	 * Unmounts the mounted Volume.
+	 * <p>
+	 * If possible, attempt a graceful unmount.
+	 *
+	 * @throws UnmountFailedException If the unmount was not successful.
+	 * @see #unmountForced()
+	 */
+	void unmout() throws UnmountFailedException;
+
+	/**
+	 * If supported, force-unmount the volume.
+	 *
+	 * @throws UnmountFailedException        If the unmount was not successful.
+	 * @throws UnsupportedOperationException If {@link MountFeature#UNMOUNT_FORCED} is not supported
+	 */
+	default void unmountForced() throws UnmountFailedException {
+		throw new UnsupportedOperationException();
+	}
+
+	default void close() throws UnmountFailedException {
+		unmout();
+	}
+
+
+}

src/main/java/org/cryptomator/integrations/mount/MountBuilder.java

@@ -0,0 +1,73 @@
+package org.cryptomator.integrations.mount;
+
+import org.jetbrains.annotations.Contract;
+import org.jetbrains.annotations.Range;
+
+import java.nio.file.Path;
+
+/**
+ * Builder to mount a filesystem.
+ * <p>
+ * The setter may attempt to validate the input, but {@link #mount()} may still fail due to missing or invalid (combination of) options.
+ * This holds especially for {@link MountBuilder#setMountFlags(String)};
+ */
+public interface MountBuilder {
+
+	/**
+	 * Sets the mount point.
+	 *
+	 * @param mountPoint Where to mount the volume
+	 * @return <code>this</code>
+	 * @see MountProvider#getDefaultMountPoint(String)
+	 */
+	@Contract("_ -> this")
+	MountBuilder setMountpoint(Path mountPoint);
+
+	/**
+	 * Sets mount flags.
+	 *
+	 * @param mountFlags Mount flags
+	 * @return <code>this</code>
+	 * @throws UnsupportedOperationException If {@link MountFeature#MOUNT_FLAGS} is not supported
+	 * @see MountProvider#getDefaultMountFlags(String)
+	 */
+	@Contract("_ -> this")
+	default MountBuilder setMountFlags(String mountFlags) {
+		throw new UnsupportedOperationException();
+	}
+
+	/**
+	 * Instructs the mount to be read-only.
+	 *
+	 * @param mountReadOnly Whether to mount read-only.
+	 * @return <code>this</code>
+	 * @throws UnsupportedOperationException If {@link MountFeature#READ_ONLY} is not supported
+	 */
+	@Contract("_ -> this")
+	default MountBuilder setReadOnly(boolean mountReadOnly) {
+		throw new UnsupportedOperationException();
+	}
+
+	/**
+	 * Use the given TCP port.
+	 *
+	 * @param port fixed TCP port or 0 to use a system-assigned port
+	 * @return <code>this</code>
+	 * @throws UnsupportedOperationException If {@link MountFeature#PORT} is not supported
+	 */
+	@Contract("_ -> this")
+	default MountBuilder setPort(@Range(from = 0, to = Short.MAX_VALUE) int port) {
+		throw new UnsupportedOperationException();
+	}
+
+
+	/**
+	 * Mounts the file system.
+	 *
+	 * @return A mount handle
+	 * @throws MountFailedException If mounting failed
+	 */
+	@Contract(" -> new")
+	Mount mount() throws MountFailedException;
+
+}

src/main/java/org/cryptomator/integrations/mount/MountFailedException.java

@@ -0,0 +1,16 @@
+package org.cryptomator.integrations.mount;
+
+public class MountFailedException extends Exception {
+
+	public MountFailedException(String msg) {
+		super(msg);
+	}
+
+	public MountFailedException(Exception cause) {
+		super(cause);
+	}
+
+	public MountFailedException(String msg, Exception cause) {
+		super(msg, cause);
+	}
+}

src/main/java/org/cryptomator/integrations/mount/MountFeature.java

@@ -0,0 +1,64 @@
+package org.cryptomator.integrations.mount;
+
+/**
+ * Describes what aspects of the mount implementation can or should be used.
+ * <p>
+ * This may be used to show or hide different configuration options depending on the chosen mount provider.
+ */
+public enum MountFeature {
+	/**
+	 * The provider supports {@link MountProvider#getDefaultMountFlags(String)}
+	 * and the builder requires {@link MountBuilder#setMountFlags(String)}.
+	 */
+	MOUNT_FLAGS,
+
+	/**
+	 * With the exception of a provider-supplied default mount point, the mount point must be an existing dir.
+	 * <p>
+	 * This option is mutually exclusive with {@link #MOUNT_WITHIN_EXISTING_PARENT}.
+	 *
+	 * @see #DEFAULT_MOUNT_POINT
+	 */
+	MOUNT_TO_EXISTING_DIR,
+
+	/**
+	 * With the exception of a provider-supplied default mount point, the mount point must be a non-existing
+	 * child within an existing parent.
+	 * <p>
+	 * This option is mutually exclusive with {@link #MOUNT_TO_EXISTING_DIR}.
+	 *
+	 * @see #DEFAULT_MOUNT_POINT
+	 */
+	MOUNT_WITHIN_EXISTING_PARENT,
+
+	/**
+	 * The mount point may be a drive letter.
+	 *
+	 * @see #MOUNT_TO_EXISTING_DIR
+	 * @see #MOUNT_WITHIN_EXISTING_PARENT
+	 */
+	MOUNT_AS_DRIVE_LETTER,
+
+	/**
+	 * The provider supports suggesting a default mount point via {@link MountProvider#getDefaultMountPoint(String)}.
+	 * <p>
+	 * The default mount point is guaranteed to be supported by the mount builder, regardless of its normal restrictions.
+	 */
+	DEFAULT_MOUNT_POINT,
+
+	/**
+	 * The builder supports {@link MountBuilder#setReadOnly(boolean)}
+	 */
+	READ_ONLY,
+
+	/**
+	 * The mount supports {@link Mount#unmountForced()}.
+	 */
+	UNMOUNT_FORCED,
+
+	/**
+	 * The provider supports {@link MountProvider#getDefaultPort()}
+	 * and the builder requires {@link MountBuilder#setPort(int)}.
+	 */
+	PORT
+}

src/main/java/org/cryptomator/integrations/mount/MountProvider.java

@@ -0,0 +1,97 @@
+package org.cryptomator.integrations.mount;
+
+import org.cryptomator.integrations.common.IntegrationsLoader;
+import org.jetbrains.annotations.Contract;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Range;
+
+import java.nio.file.Path;
+import java.util.Set;
+import java.util.stream.Stream;
+
+/**
+ * A mechanism to mount a file system.
+ *
+ * @since 1.2.0
+ */
+public interface MountProvider {
+
+	/**
+	 * Loads all supported mount providers.
+	 *
+	 * @return Stream of supported MountProviders (may be empty)
+	 */
+	static Stream<MountProvider> get() {
+		return IntegrationsLoader.loadAll(MountProvider.class).filter(MountProvider::isSupported);
+	}
+
+	/**
+	 * Name of this provider.
+	 *
+	 * @return A human readable name of this provider
+	 */
+	String displayName();
+
+	/**
+	 * Indicates, if this provider can be used.
+	 *
+	 * @return true, if this provider is supported in the current OS environment
+	 * @implSpec This check needs to return fast and in constant time
+	 */
+	boolean isSupported();
+
+	/**
+	 * A suitable mount point suggested by this provider.
+	 * <p>
+	 * Other than caller-provided mount points, the mount point suggested by this method can be
+	 * passed to {@link MountBuilder#setMountpoint(Path)} and is guaranteed to fulfill the builder's requirements
+	 * without further ado.
+	 *
+	 * @param mountPointSuffix String used in the generation of a mount point.
+	 * @return A path to a possible mount point.
+	 * @throws UnsupportedOperationException If {@link MountFeature#DEFAULT_MOUNT_POINT} is not supported
+	 */
+	default Path getDefaultMountPoint(String mountPointSuffix) {
+		throw new UnsupportedOperationException();
+	}
+
+	/**
+	 * Default mount flags. May be empty.
+	 *
+	 * @param mountName Name of the mount in the OS
+	 * @return Concatenated String of valid mount flags
+	 * @throws UnsupportedOperationException If {@link MountFeature#MOUNT_FLAGS} is not supported
+	 */
+	default String getDefaultMountFlags(String mountName) {
+		throw new UnsupportedOperationException();
+	}
+
+	/**
+	 * The default TCP port used by this provider.
+	 *
+	 * @return fixed TCP port or 0 to use a system-assigned port
+	 * @throws UnsupportedOperationException If {@link MountFeature#PORT} is not supported
+	 */
+	@Range(from = 0, to = Short.MAX_VALUE)
+	default int getDefaultPort() {
+		throw new UnsupportedOperationException();
+	}
+
+	/**
+	 * Mount features supported by this provider.
+	 *
+	 * @return Set of supported {@link MountFeature}s
+	 */
+	Set<MountFeature> supportedFeatures();
+
+
+	/**
+	 * Creates a new mount builder.
+	 *
+	 * @param fileSystemRoot The root of the VFS to be mounted
+	 * @return New mount builder
+	 */
+	@Contract("_ -> new")
+	MountBuilder forFileSystem(Path fileSystemRoot);
+
+}

src/main/java/org/cryptomator/integrations/mount/UnmountFailedException.java

@@ -0,0 +1,16 @@
+package org.cryptomator.integrations.mount;
+
+public class UnmountFailedException extends Exception {
+
+	public UnmountFailedException(String msg) {
+		super(msg);
+	}
+
+	public UnmountFailedException(Exception cause) {
+		super(cause);
+	}
+
+	public UnmountFailedException(String msg, Exception cause) {
+		super(msg, cause);
+	}
+}