GH-4950 LMDB: Correctly convert byte values to unsigned integers.

Author: kenwenzel

core/sail/lmdb/src/main/java/org/eclipse/rdf4j/sail/lmdb/inlined/Integers.java

@@ -77,7 +77,7 @@ static long packShort(Literal literal) {
 	}
 
 	static long packByte(Literal literal) {
-		return ValueIds.createId(ValueIds.T_BYTE, literal.byteValue());
+		return ValueIds.createId(ValueIds.T_BYTE, 0xFF & literal.byteValue());
 	}
 
 	static long packUnsignedLong(Literal literal) {

core/sail/lmdb/src/test/java/org/eclipse/rdf4j/sail/lmdb/inlined/StringsTest.java

@@ -11,6 +11,7 @@
 package org.eclipse.rdf4j.sail.lmdb.inlined;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
 import static org.junit.jupiter.api.Assertions.assertNotEquals;
 
 import org.eclipse.rdf4j.model.Literal;
@@ -26,6 +27,7 @@ void testPackStringWithinMaxLength() {
 		ValueFactory valueFactory = SimpleValueFactory.getInstance();
 		Literal literal = valueFactory.createLiteral("test", XSD.STRING);
 		long packed = Strings.packString(literal);
+		assertFalse(packed < 0, "Packed value should be non-negative for value: " + literal);
 
 		// Assert that the packed value is not 0
 		assertNotEquals(0L, packed, "Packed value should not be 0 for valid input.");
@@ -38,6 +40,7 @@ void testPackStringExceedsMaxLength() {
 		String longString = "a".repeat(Values.MAX_LENGTH);
 		Literal literal = valueFactory.createLiteral(longString, XSD.STRING);
 		long packed = Strings.packString(literal);
+		assertFalse(packed < 0, "Packed value should be non-negative for value: " + literal);
 
 		// Assert that the packed value is 0
 		assertEquals(0L, packed, "Packed value should be 0 for input exceeding max length.");
@@ -48,6 +51,7 @@ void testUnpackString() {
 		ValueFactory valueFactory = SimpleValueFactory.getInstance();
 		Literal literal = valueFactory.createLiteral("test", XSD.STRING);
 		long packed = Strings.packString(literal);
+		assertFalse(packed < 0, "Packed value should be non-negative for value: " + literal);
 
 		Literal unpackedLiteral = Strings.unpackString(packed, valueFactory);
 

core/sail/lmdb/src/test/java/org/eclipse/rdf4j/sail/lmdb/inlined/ValuesTest.java

@@ -11,6 +11,7 @@
 package org.eclipse.rdf4j.sail.lmdb.inlined;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.junit.jupiter.api.Assertions.assertFalse;
 
 import java.math.BigDecimal;
 import java.math.BigInteger;
@@ -146,6 +147,8 @@ void testPackAndUnpack_AllLiteralTypesWithEdgeAndStandardCases() {
 		for (Literal literal : literals) {
 			try {
 				long packed = Values.packLiteral(literal);
+				assertFalse(packed < 0, "Packed value should be non-negative for value: " + literal);
+
 				// If the literal is not inlined, packed==0. Only test roundtrip if it is inlined.
 				if (packed != 0L) {
 					Literal unpacked = Values.unpackLiteral(packed, vf);
@@ -165,6 +168,8 @@ void testPackAndUnpack_AllLiteralTypesWithVarintConversion() {
 		ByteBuffer bb = ByteBuffer.allocate(Long.BYTES + 1);
 		for (Literal literal : literals) {
 			long packed = Values.packLiteral(literal);
+			assertFalse(packed < 0, "Packed value should be non-negative for value: " + literal);
+
 			// If the literal is not inlined, packed==0. Only test roundtrip if it is inlined.
 			if (packed != 0L) {
 				bb.clear();