Testcases for ArrayBuffer offset

tests/api/test-bug-bufferobject-arraybuffer-offset-length.c

@@ -0,0 +1,74 @@
+/*===
+*** test_basic (duk_safe_call)
+uint8array index 10: 20
+arraybuffer index 10: 10
+arraybuffer index byteOffset + 10: 20
+uint8array index 10: 20
+arraybuffer index 10: 10
+arraybuffer index byteOffset + 10: 20
+final top: 0
+==> rc=0, result='undefined'
+===*/
+
+static duk_ret_t test_basic(duk_context *ctx, void *udata) {
+	unsigned char *p;
+	int i;
+
+	(void) udata;
+
+	p = (unsigned char *) duk_push_fixed_buffer(ctx, 128);
+	for (i = 0; i < 128; i++) {
+		p[i] = (unsigned char) i;
+	}
+
+	duk_push_buffer_object(ctx, -1, 10, 40, DUK_BUFOBJ_UINT8ARRAY);
+
+	/* Up to Duktape 1.6.x duk_push_buffer_object() creates an Uint8Array
+	 * with a certain offset/length, and uses that same offset/length for
+	 * the underlying ArrayBuffer.
+	 *
+	 * This makes the ArrayBuffer offsetted (offset != 0).  It also means
+	 * that accessing the ArrayBuffer at index .byteOffset + N does -not-
+	 * match Uint8Array at offset N as one would normally expect.  Instead
+	 * the .byteOffset is already account for in the ArrayBuffer internally.
+	 *
+	 * Duktape 1.7.x and 2.0.x changes this so that the .byteOffset is 0,
+	 * and the ArrayBuffer .byteLength is set to .byteOffset + .byteLength
+	 * so that the entire constructed view is visible also in the ArrayBuffer.
+	 */
+
+	duk_eval_string(ctx,
+		"(function (buf) {\n"
+		"    var arrbuf = buf.buffer;\n"
+		"    print('uint8array index 10:', buf[10]);\n"
+		"    print('arraybuffer index 10:', new Uint8Array(arrbuf)[10]);\n"
+		"    var byteOffset = buf.byteOffset;\n"
+		"    print('arraybuffer index byteOffset + 10:', new Uint8Array(arrbuf)[byteOffset + 10]);\n"
+		"})");
+	duk_dup(ctx, -2);
+	duk_call(ctx, 1);
+
+	duk_pop(ctx);  /* eval result */
+	duk_pop_2(ctx);  /* fixed buffer, buffer object */
+
+	/* Ecmascript equivalent. */
+
+	duk_eval_string_noresult(ctx,
+		"(function (buf) {\n"
+	        "    var arrbuf = new ArrayBuffer(50);\n"
+		"    var u8 = new Uint8Array(arrbuf);  // for init\n"
+		"    for (var i = 0; i < 50; i++) { u8[i] = i; }\n"
+		"    var buf = new Uint8Array(arrbuf, 10, 40);\n"
+		"    print('uint8array index 10:', buf[10]);\n"
+		"    print('arraybuffer index 10:', new Uint8Array(arrbuf)[10]);\n"
+		"    var byteOffset = buf.byteOffset;\n"
+		"    print('arraybuffer index byteOffset + 10:', new Uint8Array(arrbuf)[byteOffset + 10]);\n"
+		"})()");
+
+	printf("final top: %ld\n", (long) duk_get_top(ctx));
+	return 0;
+}
+
+void test(duk_context *ctx) {
+	TEST_SAFE_CALL(test_basic);
+}

tests/api/test-push-buffer-object.c

@@ -146,12 +146,12 @@ false false false false true false false false false false false false -> Uint8A
 [object ArrayBuffer]
 function undefined false false
 [object ArrayBuffer]
-object [object ArrayBuffer] undefined undefined 22 undefined undefined
+object [object ArrayBuffer] undefined undefined 38 undefined undefined
 false true false false false false false false false false false false -> ArrayBuffer
 false true false false false false false false false false false false -> ArrayBuffer.prototype
 undefined
 undefined
-22
+38
 undefined
 undefined
 123 123
@@ -195,7 +195,7 @@ static duk_ret_t test_view_buffer_prop(duk_context *ctx, void *udata) {
 		"    print(v.buffer.BYTES_PER_ELEMENT);\n"
 		"    print(v.buffer.buffer);\n"
 		"    v[3] = 123;  /* check that backing buffer and slice matches */\n"
-		"    print(v[3], new Uint8Array(v.buffer)[3]);\n"
+		"    print(v[3], new Uint8Array(v.buffer)[v.byteOffset + 3]);\n"
 		"})");
 	duk_dup(ctx, -2);
 	duk_call(ctx, 1);
@@ -389,7 +389,7 @@ final top: 2
 ==> rc=1, result='TypeError: invalid args'
 ===*/
 
-/* If 'flags' is given as zero, it will match a DUK_BUFOBJ_DUKTAPEBUFFER.
+/* If 'flags' is given as zero, it will match a DUK_BUFOBJ_ARRAYBUFFER.
  * So this test succeeds which is intentional.
  */
 static duk_ret_t test_invalid_flags1(duk_context *ctx, void *udata) {