unify constants given through the spec and fix wrong constant

Author: infeo

src/main/java/org/cryptomator/cryptofs/common/Constants.java

@@ -29,7 +29,9 @@ private Constants() {
 
 	public static final int MAX_SYMLINK_LENGTH = 32767; // max path length on NTFS and FAT32: 32k-1
 	public static final int MAX_DIR_ID_LENGTH = 36; // UUIDv4: hex-encoded 16 byte int + 4 hyphens = 36 ASCII chars
-	public static final int MIN_CIPHER_NAME_LENGTH = 26; //rounded up base64url encoded (16 bytes IV + 0 bytes empty string) + file suffix = 26 ASCII chars
+	public static final int MAX_CIPHER_NAME_LENGTH = 220; // calculations done in https://github.com/cryptomator/cryptofs/issues/60#issuecomment-523238303
+	public static final int MIN_CIPHER_NAME_LENGTH = 28; //rounded up base64url encoded (16 bytes IV + 0 bytes empty string) + file suffix = 28 ASCII chars
+	public static final int MAX_ADDITIONAL_PATH_LENGTH = 48; // beginning at d/... see https://github.com/cryptomator/cryptofs/issues/77
 
 	public static final String SEPARATOR = "/";
 	public static final String RECOVERY_DIR_NAME = "LOST+FOUND";

src/main/java/org/cryptomator/cryptofs/common/FileSystemCapabilityChecker.java

@@ -21,9 +21,6 @@
 public class FileSystemCapabilityChecker {
 
 	private static final Logger LOG = LoggerFactory.getLogger(FileSystemCapabilityChecker.class);
-	private static final int MAX_CIPHERTEXT_NAME_LENGTH = 220; // inclusive. calculations done in https://github.com/cryptomator/cryptofs/issues/60#issuecomment-523238303
-	private static final int MIN_CIPHERTEXT_NAME_LENGTH = 28; // base64(iv).c9r
-	private static final int MAX_ADDITIONAL_PATH_LENGTH = 48; // beginning at d/... see https://github.com/cryptomator/cryptofs/issues/77
 
 	public enum Capability {
 		/**
@@ -95,7 +92,7 @@ public void assertWriteAccess(Path pathToVault) throws MissingCapabilityExceptio
 
 	public int determineSupportedCleartextFileNameLength(Path pathToVault) throws IOException {
 		int maxCiphertextLen = determineSupportedCiphertextFileNameLength(pathToVault);
-		assert maxCiphertextLen >= MIN_CIPHERTEXT_NAME_LENGTH;
+		assert maxCiphertextLen >= Constants.MIN_CIPHER_NAME_LENGTH;
 		// math explained in https://github.com/cryptomator/cryptofs/issues/60#issuecomment-523238303;
 		// subtract 4 for file extension, base64-decode, subtract 16 for IV
 		return (maxCiphertextLen - 4) / 4 * 3 - 16;
@@ -109,8 +106,8 @@ public int determineSupportedCleartextFileNameLength(Path pathToVault) throws IO
 	 * @throws IOException If unable to perform this check
 	 */
 	public int determineSupportedCiphertextFileNameLength(Path pathToVault) throws IOException {
-		int subPathLength = MAX_ADDITIONAL_PATH_LENGTH - 2; // subtract "c/"
-		return determineSupportedCiphertextFileNameLength(pathToVault.resolve("c"), subPathLength, MIN_CIPHERTEXT_NAME_LENGTH, MAX_CIPHERTEXT_NAME_LENGTH);
+		int subPathLength = Constants.MAX_ADDITIONAL_PATH_LENGTH - 2; // subtract "c/"
+		return determineSupportedCiphertextFileNameLength(pathToVault.resolve("c"), subPathLength, Constants.MIN_CIPHER_NAME_LENGTH, Constants.MAX_CIPHER_NAME_LENGTH);
 	}
 
 	/**

src/test/java/org/cryptomator/cryptofs/dir/DirectoryStreamFactoryTest.java

@@ -3,6 +3,7 @@
 import org.cryptomator.cryptofs.CiphertextDirectory;
 import org.cryptomator.cryptofs.CryptoPath;
 import org.cryptomator.cryptofs.CryptoPathMapper;
+import org.cryptomator.cryptofs.common.Constants;
 import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.DisplayName;
@@ -118,10 +119,10 @@ public void testCiphertextDirStreamFilter(String fileName, boolean expected) {
 
 	private static Stream<Arguments> provideFilterExamples() {
 		return Stream.of( //
-				Arguments.of("foo25____25chars_____.c9r", false), //
-				Arguments.of("bar25____25chars_____.c9s", false), //
-				Arguments.of("foo26____26chars______.c9r", true), //
-				Arguments.of("bar26____26chars______.c9s", true));
+				Arguments.of("b".repeat(Constants.MIN_CIPHER_NAME_LENGTH - 5)+".c9r", false), //
+				Arguments.of("b".repeat(Constants.MIN_CIPHER_NAME_LENGTH - 5)+".c9s", false), //
+				Arguments.of("a".repeat(Constants.MIN_CIPHER_NAME_LENGTH - 4)+".c9r", true), //
+				Arguments.of("a".repeat(Constants.MIN_CIPHER_NAME_LENGTH - 4)+".c9s", true));
 	}
 
 }