closes #18

src/main/java/org/cryptomator/frontend/fuse/mount/MacMounter.java

@@ -1,16 +1,30 @@
 package org.cryptomator.frontend.fuse.mount;
 
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import javax.xml.stream.FactoryConfigurationError;
+import javax.xml.stream.XMLInputFactory;
+import javax.xml.stream.XMLStreamException;
+import javax.xml.stream.XMLStreamReader;
 import java.io.IOException;
+import java.io.InputStream;
 import java.io.UncheckedIOException;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.Paths;
+import java.nio.file.StandardOpenOption;
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.concurrent.TimeUnit;
 
 class MacMounter implements Mounter {
 
+	private static final Logger LOG = LoggerFactory.getLogger(MacMounter.class);
 	private static final boolean IS_MAC = System.getProperty("os.name").toLowerCase().contains("mac");
+	private static final int[] OSXFUSE_MINIMUM_SUPPORTED_VERSION = new int[]{3, 8, 2};
+	private static final Path OSXFUSE_VERSIONFILE_LOCATION = Paths.get("/Library/Filesystems/osxfuse.fs/Contents/version.plist");
+	private static final String OSXFUSE_XML_VERSION_TEXT = "CFBundleShortVersionString";
 
 	@Override
 	public Mount mount(Path directory, EnvironmentVariables envVars, String... additionalMountParams) throws CommandFailedException {
@@ -20,11 +34,56 @@ public Mount mount(Path directory, EnvironmentVariables envVars, String... addit
 	}
 
 	/**
-	 * @return <code>true</code> if on OS X and osxfuse is installed.
+	 * @return <code>true</code> if on OS X and osxfuse with a higher version than the minimum supported one is installed.
 	 */
 	@Override
 	public boolean isApplicable() {
-		return IS_MAC && Files.exists(Paths.get("/usr/local/lib/libosxfuse.2.dylib"));
+		return IS_MAC && Files.exists(Paths.get("/usr/local/lib/libosxfuse.2.dylib")) && installedVersionSupported();
+	}
+
+	public boolean installedVersionSupported() {
+		String versionString = getVersionString();
+		if (versionString == null) {
+			LOG.error("Did not find {} in document {}.", OSXFUSE_XML_VERSION_TEXT, OSXFUSE_VERSIONFILE_LOCATION);
+			return false;
+		}
+
+		Integer[] parsedVersion = Arrays.stream(versionString.split("\\.")).map(s -> Integer.valueOf(s)).toArray(Integer[]::new);
+		for (int i = 0; i < OSXFUSE_MINIMUM_SUPPORTED_VERSION.length && i < parsedVersion.length; i++) {
+			if (parsedVersion[i] < OSXFUSE_MINIMUM_SUPPORTED_VERSION[i]) {
+				return false;
+			} else if (parsedVersion[i] > OSXFUSE_MINIMUM_SUPPORTED_VERSION[i]) {
+				return true;
+			}
+		}
+
+		if (OSXFUSE_MINIMUM_SUPPORTED_VERSION.length <= parsedVersion.length) {
+			return true;
+		} else {
+			return false;
+		}
+	}
+
+
+	private String getVersionString() {
+		String version = null;
+		try (InputStream in = Files.newInputStream(OSXFUSE_VERSIONFILE_LOCATION, StandardOpenOption.READ)) {
+			XMLStreamReader reader = XMLInputFactory.newInstance().createXMLStreamReader(in);
+			while (reader.hasNext()) {
+				reader.next();
+				if (reader.getEventType() == XMLStreamReader.CHARACTERS && OSXFUSE_XML_VERSION_TEXT.equalsIgnoreCase(reader.getText())) {
+					reader.next();
+					reader.next();
+					reader.next();
+					version = reader.getElementText();
+				}
+			}
+		} catch (XMLStreamException | FactoryConfigurationError e) {
+			LOG.error("Could not parse file {} to detect version of OSXFUSE.", OSXFUSE_VERSIONFILE_LOCATION);
+		} catch (IOException e1) {
+			LOG.error("Could not read file {} to detect version of OSXFUSE.", OSXFUSE_VERSIONFILE_LOCATION);
+		}
+		return version;
 	}
 
 	private static class MacMount extends AbstractMount {