make sure there is an exception if the file is corrupt

performanceDb/src/main/java/org/lucares/performance/db/ByteType.java

@@ -13,9 +13,9 @@ enum ByteType {
 	VERSION(1);// 00000001
 
 	interface ContinuationByte {
-		long NUMBER_OF_VALUES_BITS = 7;
+		int NUMBER_OF_VALUES_BITS = 7;
 
-		long CONTINUATION_BYTE_PREFIX = 1 << NUMBER_OF_VALUES_BITS; // 10000000
+		int CONTINUATION_BYTE_PREFIX = 1 << NUMBER_OF_VALUES_BITS; // 10000000
 	}
 
 	interface VersionByte {
@@ -24,19 +24,23 @@ enum ByteType {
 		 * which cannot hold any value (unless it is 0). And the second byte is
 		 * the actual value.
 		 */
-		long MIN_LENGTH = 2;
+		int MIN_LENGTH = 2;
 	}
 
-	private final long firstBytePrefix;
+	private final int firstBytePrefix;
 
-	private ByteType(final long firstBytePrefix) {
+	private ByteType(final int firstBytePrefix) {
 		this.firstBytePrefix = firstBytePrefix;
 	}
 
-	public long getBytePrefix() {
+	public int getBytePrefix() {
 		return firstBytePrefix;
 	}
 
+	public byte getBytePrefixAsByte() {
+		return (byte) firstBytePrefix;
+	}
+
 	/**
 	 * the max value for the first byte is the prefix minus 1, because prefixes
 	 * start with 0⋯010⋯0, so prefix -1 is 0⋯01⋯1 which is exactly the max value
@@ -53,7 +57,7 @@ enum ByteType {
 	 *
 	 * @return bitmap with the value bits set
 	 */
-	public long getValueBits() {
+	public int getValueBits() {
 		return firstBytePrefix - 1;
 	}
 
@@ -64,7 +68,7 @@ enum ByteType {
 		return firstBytePrefix == (theByte & prefixBits);
 	}
 
-	public long getPrefixBits() {
+	public int getPrefixBits() {
 		return (~getValueBits()) & 0xff;
 	}
 
@@ -78,7 +82,7 @@ enum ByteType {
 		return null;
 	}
 
-	public long getValue(final int aByte) {
+	public int getValue(final int aByte) {
 		return aByte & getValueBits();
 	}
 }

performanceDb/src/main/java/org/lucares/performance/db/PdbReader.java

@@ -90,6 +90,7 @@ class PdbReader implements AutoCloseable {
 	}
 
 	Entry readNullableEntry() throws ReadRuntimeException {
+
 		try {
 			final long epochMilliIncrement = readValue(ByteType.DATE_INCREMENT);
 			if (epochMilliIncrement < 0) {
@@ -127,6 +128,7 @@ class PdbReader implements AutoCloseable {
 
 		if (!byteType.isValid(firstByte)) {
 			if (firstByte < 0) {
+				// end of file reached
 				return -1;
 			} else if (ByteType.DATE_OFFSET.isValid(firstByte)) {
 				final long dateOffsetInit = firstByte & ByteType.DATE_OFFSET.getValueBits();

performanceDb/src/test/java/org/lucares/performance/db/PdbReaderWriterTest.java

@@ -4,6 +4,7 @@ import java.io.File;
 import java.io.IOException;
 import java.nio.file.Files;
 import java.nio.file.Path;
+import java.nio.file.StandardOpenOption;
 import java.time.Instant;
 import java.time.OffsetDateTime;
 import java.time.ZoneId;
@@ -88,6 +89,39 @@ public class PdbReaderWriterTest {
 
 				Assert.assertEquals(actual, entry);
 			}
+			reader.readEntry().ifPresent(e -> {
+				throw new AssertionError();
+			});
+		}
+	}
+
+	@Test(expectedExceptions = FileCorruptException.class)
+	public void testReadExceptionOnCorruptEntries() throws Exception {
+
+		final Entry entryA = new Entry(1, 1, TAGS);
+
+		final File file = Files.createTempFile(dataDirectory, "pdb", ".db").toFile();
+		final PdbFile pdbFile = new PdbFile(file.toPath(), TAGS);
+
+		try (PdbWriter writer = new PdbWriter(pdbFile)) {
+			writer.write(entryA);
+		}
+
+		// make the file corrupt
+		// two date consecutive increments will never happen in valid data
+		final byte[] corruptEntries = new byte[] { //
+				ByteType.DATE_INCREMENT.getBytePrefixAsByte(), //
+				ByteType.DATE_INCREMENT.getBytePrefixAsByte() //
+		};
+
+		Files.write(file.toPath(), corruptEntries, StandardOpenOption.APPEND);
+
+		try (final PdbReader reader = new PdbReader(pdbFile)) {
+
+			final Entry actualA = reader.readEntry().orElseThrow(() -> new AssertionError());
+			Assert.assertEquals(actualA, entryA);
+
+			reader.readEntry(); // should throw FileCorruptException
 		}
 	}
 }