allow readonly file channels even when exceeding maxCleartextNameLength

Author: overheadhunter

src/main/java/org/cryptomator/cryptofs/CryptoFileSystemImpl.java

@@ -348,7 +348,9 @@ private FileChannel newFileChannelFromSymlink(CryptoPath cleartextPath, Effectiv
 	}
 
 	private FileChannel newFileChannelFromFile(CryptoPath cleartextFilePath, EffectiveOpenOptions options, FileAttribute<?>... attrs) throws IOException {
-		assertCleartextNameLengthAllowed(cleartextFilePath);
+		if (options.create() || options.createNew()) {
+			assertCleartextNameLengthAllowed(cleartextFilePath);
+		}
 		CiphertextFilePath ciphertextPath = cryptoPathMapper.getCiphertextFilePath(cleartextFilePath);
 		Path ciphertextFilePath = ciphertextPath.getFilePath();
 		if (options.createNew() && openCryptoFiles.get(ciphertextFilePath).isPresent()) {

src/main/java/org/cryptomator/cryptofs/CryptoFileSystemProperties.java

@@ -152,7 +152,7 @@ String masterkeyFilename() {
 		return (String) get(PROPERTY_MASTERKEY_FILENAME);
 	}
 
-	public int maxCleartextNameLength() {
+	int maxCleartextNameLength() {
 		return (int) get(PROPERTY_MAX_CLEARTEXT_NAME_LENGTH);
 	}
 
@@ -235,9 +235,11 @@ private <T> void checkedSet(Class<T> type, String key, Map<String, ?> properties
 		}
 
 		/**
-		 * Sets the maximum ciphertext filename length for a CryptoFileSystem.
+		 * Sets the maximum cleartext filename length for a CryptoFileSystem. This value is checked during write
+		 * operations. Read access to nodes with longer names should be unaffected. Setting this value to {@code 0} or
+		 * a negative value effectively disables write access.
 		 *
-		 * @param maxCleartextNameLength The maximum ciphertext filename length allowed
+		 * @param maxCleartextNameLength The maximum cleartext filename length allowed
 		 * @return this
 		 * @since 2.0.0
 		 */

src/test/java/org/cryptomator/cryptofs/CryptoFileSystemImplTest.java

@@ -19,6 +19,7 @@
 import org.hamcrest.CoreMatchers;
 import org.hamcrest.MatcherAssert;
 import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Assumptions;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.DisplayName;
 import org.junit.jupiter.api.Nested;
@@ -367,6 +368,50 @@ public void setup() throws IOException {
 			when(openCryptoFile.newFileChannel(any())).thenReturn(fileChannel);
 		}
 
+		@Nested
+		public class LimitedCleartextNameLength {
+
+			@BeforeEach
+			public void setup() throws IOException {
+				Assumptions.assumeTrue(cleartextPath.getFileName().toString().length() == 9);
+			}
+
+			@Test
+			@DisplayName("read-only always works")
+			public void testNewFileChannelReadOnlyDespiteMaxName() throws IOException {
+				Mockito.doReturn(0).when(fileSystemProperties).maxCleartextNameLength();
+
+				FileChannel ch = inTest.newFileChannel(cleartextPath, EnumSet.of(StandardOpenOption.READ));
+
+				Assertions.assertSame(fileChannel, ch);
+				verify(readonlyFlag, Mockito.never()).assertWritable();
+			}
+
+			@Test
+			@DisplayName("create new fails when exceeding limit")
+			public void testNewFileChannelCreate1() {
+				Mockito.doReturn(0).when(fileSystemProperties).maxCleartextNameLength();
+
+				Assertions.assertThrows(FileNameTooLongException.class, () -> {
+					inTest.newFileChannel(cleartextPath, EnumSet.of(StandardOpenOption.WRITE, StandardOpenOption.CREATE));
+				});
+
+				verifyNoInteractions(openCryptoFiles);
+			}
+
+			@Test
+			@DisplayName("create new succeeds when within limit")
+			public void testNewFileChannelCreate2() throws IOException {
+				Mockito.doReturn(10).when(fileSystemProperties).maxCleartextNameLength();
+
+				FileChannel ch = inTest.newFileChannel(cleartextPath, EnumSet.of(StandardOpenOption.READ));
+
+				Assertions.assertSame(fileChannel, ch);
+				verify(readonlyFlag, Mockito.never()).assertWritable();
+			}
+
+		}
+
 		@Test
 		@DisplayName("newFileChannel read-only")
 		public void testNewFileChannelReadOnly() throws IOException {