fixes #59

Author: overheadhunter

src/main/java/org/cryptomator/cryptofs/attr/CryptoBasicFileAttributes.java

@@ -54,7 +54,7 @@ public CryptoBasicFileAttributes(BasicFileAttributes delegate, CiphertextFileTyp
 	}
 
 	private static long getPlaintextFileSize(Path ciphertextPath, long size, Optional<OpenCryptoFile> openCryptoFile, Cryptor cryptor) {
-		return openCryptoFile.map(OpenCryptoFile::size).orElseGet(() -> calculatePlaintextFileSize(ciphertextPath, size, cryptor));
+		return openCryptoFile.flatMap(OpenCryptoFile::size).orElseGet(() -> calculatePlaintextFileSize(ciphertextPath, size, cryptor));
 	}
 
 	private static long calculatePlaintextFileSize(Path ciphertextPath, long size, Cryptor cryptor) {

src/main/java/org/cryptomator/cryptofs/fh/OpenCryptoFile.java

@@ -25,6 +25,7 @@
 import java.nio.file.Path;
 import java.nio.file.attribute.FileTime;
 import java.time.Instant;
+import java.util.Optional;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.ConcurrentMap;
 import java.util.concurrent.atomic.AtomicLong;
@@ -146,12 +147,15 @@ private void initFileSize(FileChannel ciphertextFileChannel) throws IOException
 	}
 
 	/**
-	 * @return The size of the opened file
-	 * @throws IllegalStateException If the OpenCryptoFile {@link OpenCryptoFiles#getOrCreate(Path) has been created} without {@link #newFileChannel(EffectiveOpenOptions) creating a file channel} next.
+	 * @return The size of the opened file. Note that the filesize is unknown until a {@link #newFileChannel(EffectiveOpenOptions) file channel is opened}. In this case this method returns an empty optional.
 	 */
-	public long size() {
-		Preconditions.checkState(fileSize.get() != -1l, "size must only be called after a FileChannel is created for this OpenCryptoFile");
-		return fileSize.get();
+	public Optional<Long> size() {
+		long val = fileSize.get();
+		if (val == -1l) {
+			return Optional.empty();
+		} else {
+			return Optional.of(val);
+		}
 	}
 
 	public FileTime getLastModifiedTime() {

src/test/java/org/cryptomator/cryptofs/fh/OpenCryptoFileTest.java

@@ -124,9 +124,7 @@ public void setup() throws IOException {
 		@Order(0)
 		@DisplayName("getting size fails before creating first file channel")
 		public void testGetSizeBeforeCreatingFileChannel() {
-			Assertions.assertThrows(IllegalStateException.class, () -> {
-				openCryptoFile.size();
-			});
+			Assertions.assertFalse(openCryptoFile.size().isPresent());
 		}
 
 		@Test
@@ -143,7 +141,7 @@ public void createFileChannel() throws IOException {
 		@Order(11)
 		@DisplayName("getting size succeeds after creating first file channel")
 		public void testGetSizeAfterCreatingFirstFileChannel() {
-			Assertions.assertEquals(0l, openCryptoFile.size());
+			Assertions.assertEquals(0l, openCryptoFile.size().get());
 		}
 
 		// related to https://github.com/cryptomator/cryptofs/issues/51
@@ -166,7 +164,7 @@ public void errorDuringCreationOfSecondChannel() {
 		@Order(13)
 		@DisplayName("getting size succeeds after creating second file channel")
 		public void testGetSizeAfterCreatingSecondFileChannel() {
-			Assertions.assertEquals(0l, openCryptoFile.size());
+			Assertions.assertEquals(0l, openCryptoFile.size().get());
 		}