Fix number to boolean conversion

src/main/java/jnr/ffi/provider/jffi/DefaultInvokerFactory.java

@@ -506,6 +506,9 @@ public final Object invoke(Runtime runtime, Function function, HeapInvocationBuf
     static class BooleanInvoker extends BaseInvoker {
         static FunctionInvoker INSTANCE = new BooleanInvoker();
         public final Object invoke(Runtime runtime, Function function, HeapInvocationBuffer buffer) {
+            if (function.getReturnType().size() == 8) {
+                return invoker.invokeLong(function, buffer) != 0;
+            }
             return invoker.invokeInt(function, buffer) != 0;
         }
     }

src/main/java/jnr/ffi/provider/jffi/NumberUtil.java

@@ -20,6 +20,7 @@
 
 import jnr.ffi.NativeType;
 import jnr.ffi.provider.SigType;
+import org.objectweb.asm.Label;
 
 public final class NumberUtil {
     private NumberUtil() {}
@@ -144,23 +145,40 @@ public static void widen(SkinnyMethodAdapter mv, Class from, Class to, NativeTyp
     public static void narrow(SkinnyMethodAdapter mv, Class from, Class to) {
         if (!from.equals(to)) {
             if (byte.class == to || short.class == to || char.class == to || int.class == to || boolean.class == to) {
-                if (long.class == from) {
-                    mv.l2i();
-                }
+                if (boolean.class == to) {
+                    if (long.class == from) {
+                        mv.lconst_0();
+                        mv.lcmp();
+
+                    } else {
+                        /* Equivalent to
+                           return result == 0 ? true : false;
+                         */
+                        Label zero = new Label();
+                        Label ret = new Label();
+                        mv.iconst_0();
+                        mv.if_icmpeq(zero);
+                        mv.iconst_1();
+                        mv.go_to(ret);
+                        mv.label(zero);
+                        mv.iconst_0();
+                        mv.label(ret);
+                    }
+                } else {
+                    if (long.class == from) {
+                        mv.l2i();
+                    }
 
-                if (byte.class == to) {
-                    mv.i2b();
+                    if (byte.class == to) {
+                        mv.i2b();
 
-                } else if (short.class == to) {
-                    mv.i2s();
+                    } else if (short.class == to) {
+                        mv.i2s();
 
-                } else if (char.class == to) {
-                    mv.i2c();
+                    } else if (char.class == to) {
+                        mv.i2c();
 
-                } else if (boolean.class == to) {
-                    // Ensure only 0x0 and 0x1 values are used for boolean
-                    mv.iconst_1();
-                    mv.iand();
+                    }
                 }
             }
         }

src/test/java/jnr/ffi/NumberTest.java

@@ -18,23 +18,25 @@
 
 package jnr.ffi;
 
+import jnr.ffi.annotations.LongLong;
+import jnr.ffi.types.int32_t;
+import jnr.ffi.types.pid_t;
+import jnr.ffi.types.u_int32_t;
+import org.junit.*;
+
 import java.util.Random;
 
-import jnr.ffi.annotations.LongLong;
-import jnr.ffi.types.*;
-import org.junit.After;
-import org.junit.AfterClass;
-import org.junit.Before;
-import org.junit.BeforeClass;
-import org.junit.Test;
-import static org.junit.Assert.*;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.fail;
 
 /**
  *
  * @author wayne
  */
 public class NumberTest {
 
+    public static final long LONG_WITH_ONLY_THIRD_WORD_NOT_ZERO = 0xFF00000000L;
+
     public NumberTest() {
     }
 
@@ -70,6 +72,7 @@ public static interface TestLib {
     public static interface TestBoolean {
 
         public boolean ret_int32_t(int l);
+        public @LongLong boolean ret_int64_t(@LongLong long l);
     }
     static TestBoolean testboolean;
 
@@ -357,4 +360,13 @@ public long n(long i1, long i2) {
         assertEquals(true, testboolean.ret_int32_t(1));
         assertEquals(true, testboolean.ret_int32_t(2));
     }
+
+    @Test public void testBooleanFromLong() throws Exception {
+        assertEquals(false, testboolean.ret_int64_t(0));
+        assertEquals(true, testboolean.ret_int64_t(-1));
+        assertEquals(true, testboolean.ret_int64_t(-5));
+        assertEquals(true, testboolean.ret_int64_t(1));
+        assertEquals(true, testboolean.ret_int64_t(2));
+        assertEquals(true, testboolean.ret_int64_t(LONG_WITH_ONLY_THIRD_WORD_NOT_ZERO));
+    }
 }