buffer: truncate instead of throw when writing beyond buffer

Fixes: #54523
Fixes: #54518
PR-URL: #54524
Reviewed-By: Ethan Arrowood <[email protected]>
Reviewed-By: Benjamin Gruenbaum <[email protected]>
Reviewed-By: Ruben Bridgewater <[email protected]>
Reviewed-By: Rafael Gonzaga <[email protected]>
Reviewed-By: Anna Henningsen <[email protected]>
Reviewed-By: Matteo Collina <[email protected]>

Author: ronag

lib/internal/buffer.js

@@ -1040,7 +1040,7 @@ function addBufferPrototypeMethods(proto) {
     if (offset < 0 || offset > this.byteLength) {
       throw new ERR_BUFFER_OUT_OF_BOUNDS('offset');
     }
-    if (length < 0 || length > this.byteLength - offset) {
+    if (length < 0) {
       throw new ERR_BUFFER_OUT_OF_BOUNDS('length');
     }
     return asciiWriteStatic(this, string, offset, length);
@@ -1051,7 +1051,7 @@ function addBufferPrototypeMethods(proto) {
     if (offset < 0 || offset > this.byteLength) {
       throw new ERR_BUFFER_OUT_OF_BOUNDS('offset');
     }
-    if (length < 0 || length > this.byteLength - offset) {
+    if (length < 0) {
       throw new ERR_BUFFER_OUT_OF_BOUNDS('length');
     }
     return latin1WriteStatic(this, string, offset, length);
@@ -1062,7 +1062,7 @@ function addBufferPrototypeMethods(proto) {
     if (offset < 0 || offset > this.byteLength) {
       throw new ERR_BUFFER_OUT_OF_BOUNDS('offset');
     }
-    if (length < 0 || length > this.byteLength - offset) {
+    if (length < 0) {
       throw new ERR_BUFFER_OUT_OF_BOUNDS('length');
     }
     return utf8WriteStatic(this, string, offset, length);

test/parallel/test-buffer-write.js

@@ -106,3 +106,18 @@ assert.strictEqual(Buffer.alloc(4)
   assert.strictEqual(buf.write('ыы', 1, 'utf16le'), 4);
   assert.deepStrictEqual([...buf], [0, 0x4b, 0x04, 0x4b, 0x04, 0, 0, 0]);
 }
+
+{
+  const buf = Buffer.alloc(1);
+  assert.strictEqual(buf.write('ww'), 1);
+  assert.strictEqual(buf.toString(), 'w');
+}
+
+assert.throws(() => {
+  const buf = Buffer.alloc(1);
+  assert.strictEqual(buf.asciiWrite('ww', 0, -1));
+  assert.strictEqual(buf.latin1Write('ww', 0, -1));
+  assert.strictEqual(buf.utf8Write('ww', 0, -1));
+}, common.expectsError({
+  code: 'ERR_BUFFER_OUT_OF_BOUNDS',
+}));