impl draft for dolphin places area

src/main/java/org/cryptomator/linux/quickaccess/DolphinPlaces.java

@@ -0,0 +1,161 @@
+package org.cryptomator.linux.quickaccess;
+
+import org.cryptomator.integrations.common.CheckAvailability;
+import org.cryptomator.integrations.common.DisplayName;
+import org.cryptomator.integrations.common.OperatingSystem;
+import org.cryptomator.integrations.common.Priority;
+import org.cryptomator.integrations.quickaccess.QuickAccessService;
+import org.cryptomator.integrations.quickaccess.QuickAccessServiceException;
+import org.xml.sax.SAXException;
+
+import javax.xml.XMLConstants;
+import javax.xml.transform.Source;
+import javax.xml.transform.stream.StreamSource;
+import javax.xml.validation.SchemaFactory;
+import javax.xml.validation.Validator;
+import java.io.IOException;
+import java.io.StringReader;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.StandardCopyOption;
+import java.nio.file.StandardOpenOption;
+import java.util.UUID;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantReadWriteLock;
+
+/**
+ * Implemenation of the {@link QuickAccessService} for KDE desktop environments using Dolphin file browser.
+ */
+@DisplayName("KDE Dolphin Places")
+@OperatingSystem(OperatingSystem.Value.LINUX)
+@Priority(90)
+public class DolphinPlaces implements QuickAccessService {
+
+	private static final int MAX_FILE_SIZE = 1 << 15; //xml is quite verbose
+	private static final Path PLACES_FILE = Path.of(System.getProperty("user.home"), ".local/share/user-places.xbel");
+	private static final Path TMP_FILE = PLACES_FILE.resolveSibling("user-places.xbel.cryptomator.tmp");
+	private static final Lock MODIFY_LOCK = new ReentrantReadWriteLock().writeLock();
+	private static final String ENTRY_TEMPLATE = """
+			<bookmark href="%s">
+			 <title>%s</title>
+			 <info>
+			  <metadata owner="http://freedesktop.org">
+			   <bookmark:icon name="drive-harddisk"/>
+			  </metadata>
+			  <metadata owner="https://cryptomator.org">
+			  	<id>%s</id>
+			  </metadata>
+			 </info>
+			</bookmark>""";
+
+
+	private static final Validator xmlValidator;
+
+	static {
+		SchemaFactory factory = SchemaFactory.newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI);
+		try (var schemaDefinition = DolphinPlaces.class.getResourceAsStream("/xbel-1.0.xsd")) {
+			Source schemaFile = new StreamSource(schemaDefinition);
+			xmlValidator = factory.newSchema(schemaFile).newValidator();
+		} catch (IOException | SAXException e) {
+			throw new IllegalStateException("Failed to load included XBEL schema definition file.", e);
+		}
+	}
+
+
+	@Override
+	public QuickAccessService.QuickAccessEntry add(Path target, String displayName) throws QuickAccessServiceException {
+		String id = UUID.randomUUID().toString();
+		try {
+			MODIFY_LOCK.lock();
+			if (Files.size(PLACES_FILE) > MAX_FILE_SIZE) {
+				throw new IOException("File %s exceeds size of %d bytes".formatted(PLACES_FILE, MAX_FILE_SIZE));
+			}
+			var placesContent = Files.readString(PLACES_FILE);
+			//validate
+			xmlValidator.validate(new StreamSource(new StringReader(placesContent)));
+			// modify
+			int insertIndex = placesContent.lastIndexOf("</xbel>"); //cannot be -1 due to validation
+			try (var writer = Files.newBufferedWriter(TMP_FILE, StandardCharsets.UTF_8, StandardOpenOption.WRITE, StandardOpenOption.CREATE, StandardOpenOption.TRUNCATE_EXISTING)) {
+				writer.write(placesContent, 0, insertIndex);
+				writer.newLine();
+				writer.write(ENTRY_TEMPLATE.formatted(target.toUri(), displayName, id).indent(1));
+				writer.newLine();
+				writer.write(placesContent, insertIndex, placesContent.length() - insertIndex);
+			}
+			// save
+			Files.move(TMP_FILE, PLACES_FILE, StandardCopyOption.REPLACE_EXISTING, StandardCopyOption.ATOMIC_MOVE);
+			return new DolphinPlacesEntry(id);
+		} catch (SAXException | IOException e) {
+			throw new QuickAccessServiceException("Adding entry to KDE places file failed.", e);
+		} finally {
+			MODIFY_LOCK.unlock();
+		}
+	}
+
+	private static class DolphinPlacesEntry implements QuickAccessEntry {
+
+		private final String id;
+		private volatile boolean isRemoved = false;
+
+		DolphinPlacesEntry(String id) {
+			this.id = id;
+		}
+
+		@Override
+		public void remove() throws QuickAccessServiceException {
+			try {
+				MODIFY_LOCK.lock();
+				if (isRemoved) {
+					return;
+				}
+				if (Files.size(PLACES_FILE) > MAX_FILE_SIZE) {
+					throw new IOException("File %s exceeds size of %d bytes".formatted(PLACES_FILE, MAX_FILE_SIZE));
+				}
+				var placesContent = Files.readString(PLACES_FILE);
+				int idIndex = placesContent.lastIndexOf(id);
+				if (idIndex == -1) {
+					isRemoved = true;
+					return; //we assume someone has removed our entry
+				}
+				//validate
+				xmlValidator.validate(new StreamSource(new StringReader(placesContent)));
+				//modify
+				var placesContentPart1 = placesContent.substring(0, idIndex);
+				int openingTagIndex = placesContentPart1.lastIndexOf("<bookmark href=");
+				var contentToWrite1 = placesContentPart1.substring(0, openingTagIndex).stripTrailing();
+
+				int closingTagIndex = placesContent.indexOf("</bookmark>", idIndex);
+				var part2Tmp = placesContent.substring(closingTagIndex + "</bookmark>".length()).split("\\v*", 2); //removing leading vertical whitespaces
+				var contentToWrite2 = part2Tmp.length == 1 ? part2Tmp[0] : part2Tmp[1];
+
+				try (var writer = Files.newBufferedWriter(TMP_FILE, StandardCharsets.UTF_8, StandardOpenOption.WRITE, StandardOpenOption.CREATE, StandardOpenOption.TRUNCATE_EXISTING)) {
+					writer.write(contentToWrite1);
+					writer.newLine();
+					writer.write(contentToWrite2);
+				}
+				// save
+				Files.move(TMP_FILE, PLACES_FILE, StandardCopyOption.REPLACE_EXISTING, StandardCopyOption.ATOMIC_MOVE);
+				isRemoved = true;
+			} catch (IOException | SAXException e) {
+				throw new QuickAccessServiceException("Removing entry from KDE places file failed.", e);
+			} finally {
+				MODIFY_LOCK.unlock();
+			}
+		}
+	}
+
+	@CheckAvailability
+	public static boolean isSupported() {
+		try {
+			var nautilusExistsProc = new ProcessBuilder().command("test", "`command -v dolphin`").start();
+			if (nautilusExistsProc.waitFor(5000, TimeUnit.MILLISECONDS)) {
+				return nautilusExistsProc.exitValue() == 0;
+			}
+		} catch (IOException | InterruptedException e) {
+			//NO-OP
+		}
+		return false;
+	}
+}

src/main/resources/xbel-1.0.dtd

@@ -0,0 +1,94 @@
+<!-- This is the XML Bookmarks Exchange Language, version 1.0.  It
+     should be used with the formal public identifier:
+
+        +//IDN python.org//DTD XML Bookmark Exchange Language 1.0//EN//XML
+
+     One valid system identifier at which this DTD will remain
+     available is:
+
+        http://pyxml.sourceforge.net/topics/dtds/xbel-1.0.dtd
+
+     More information on the DTD, including reference
+     documentation, is available at:
+
+        http://www.python.org/topics/xml/xbel/
+
+    Attributes which take date/time values should encode the value
+    according to the W3C NOTE on date/time formats:
+
+        http://www.w3.org/TR/NOTE-datetime
+  -->
+
+
+<!-- Customization entities.  Define these before "including" this DTD
+     to create "subclassed" DTDs.
+  -->
+<!ENTITY % local.node.att  "">
+<!ENTITY % local.url.att   "">
+<!ENTITY % local.nodes.mix "">
+
+<!ENTITY % node.att     "id       ID    #IMPLIED
+                         added    CDATA #IMPLIED
+                         %local.node.att;">
+
+<!ENTITY % url.att      "href     CDATA #REQUIRED
+                         visited  CDATA #IMPLIED
+                         modified CDATA #IMPLIED
+                         %local.url.att;">
+
+<!ENTITY % nodes.mix    "bookmark|folder|alias|separator
+                         %local.nodes.mix;">
+
+
+<!ELEMENT xbel (title?, info?, desc?, (%nodes.mix;)*)>
+<!ATTLIST xbel
+            %node.att;
+            version  CDATA      #FIXED "1.0"
+>
+<!ELEMENT title      (#PCDATA)>
+
+<!--=================== Info ======================================-->
+
+<!ELEMENT info (metadata+)>
+
+<!ELEMENT metadata EMPTY>
+<!ATTLIST metadata
+            owner    CDATA      #REQUIRED
+>
+
+<!--=================== Folder ====================================-->
+
+<!ELEMENT folder   (title?, info?, desc?, (%nodes.mix;)*)>
+<!ATTLIST folder
+            %node.att;
+            folded   (yes|no)   'yes'   
+>
+
+<!--=================== Bookmark ==================================-->
+
+<!ELEMENT bookmark (title?, info?, desc?)>
+<!ATTLIST bookmark
+            %node.att;
+            %url.att;
+>
+
+<!ELEMENT desc       (#PCDATA)>
+
+<!--=================== Separator =================================-->
+
+<!ELEMENT separator EMPTY>
+
+<!--=================== Alias =====================================-->
+
+<!-- <alias> elements correspond to Netscape bookmark aliases.  The
+     required "ref" attribute must refer to a <bookmark> or <folder>
+     element.  Note that MSIE aliases can refer to folders, so that is
+     supported in XBEL.  Applications must be careful about traversing
+     aliases to folders to avoid improper recursion through circular
+     data structures.
+  -->
+
+<!ELEMENT alias EMPTY>
+<!ATTLIST alias
+            ref       IDREF     #REQUIRED
+>