test,doc: cover and document multi-byte offset/size in randomFill

Signed-off-by: kyungrae <kyungrae2002@gmail.com>
PR-URL: #64834
Reviewed-By: Daeyeon Jeong <daeyeon.dev@gmail.com>

Author: kyungrae2002

doc/api/crypto.md

@@ -5660,9 +5660,12 @@ changes:
 
 * `buffer` {ArrayBuffer|Buffer|TypedArray|DataView} Must be supplied. The
   size of the provided `buffer` must not be larger than `2**31 - 1`.
-* `offset` {number} **Default:** `0`
-* `size` {number} **Default:** `buffer.length - offset`. The `size` must
-  not be larger than `2**31 - 1`.
+* `offset` {number} The start position, in elements for a `TypedArray` and in
+  bytes for an `ArrayBuffer` or `DataView`. **Default:** `0`
+* `size` {number} The amount to fill, in the same units as `offset`.
+  **Default:** `buffer.length - offset` for a `TypedArray`, or
+  `buffer.byteLength - offset` for an `ArrayBuffer` or `DataView`. The `size`
+  must not be larger than `2**31 - 1`.
 * `callback` {Function} `function(err, buf) {}`.
 
 This function is similar to [`crypto.randomBytes()`][] but requires the first
@@ -5797,9 +5800,12 @@ changes:
 
 * `buffer` {ArrayBuffer|Buffer|TypedArray|DataView} Must be supplied. The
   size of the provided `buffer` must not be larger than `2**31 - 1`.
-* `offset` {number} **Default:** `0`
-* `size` {number} **Default:** `buffer.length - offset`. The `size` must
-  not be larger than `2**31 - 1`.
+* `offset` {number} The start position, in elements for a `TypedArray` and in
+  bytes for an `ArrayBuffer` or `DataView`. **Default:** `0`
+* `size` {number} The amount to fill, in the same units as `offset`.
+  **Default:** `buffer.length - offset` for a `TypedArray`, or
+  `buffer.byteLength - offset` for an `ArrayBuffer` or `DataView`. The `size`
+  must not be larger than `2**31 - 1`.
 * Returns: {ArrayBuffer|Buffer|TypedArray|DataView} The object passed as
   `buffer` argument.
 

lib/internal/crypto/random.js

@@ -168,7 +168,7 @@ function randomFill(buf, offset, size, callback) {
     size = buf.length;
   } else if (typeof size === 'function') {
     callback = size;
-    size = buf.length - offset;
+    size = (buf.length ?? buf.byteLength) - offset;
   } else {
     validateFunction(callback, 'callback');
   }

test/parallel/test-crypto-random.js

@@ -218,6 +218,55 @@ common.expectWarning('DeprecationWarning',
   }));
 }
 
+{
+  const buf = new Uint16Array(10);
+  const before = Buffer.from(buf.buffer).toString('hex');
+  crypto.randomFillSync(buf, 1, 8);
+  const after = Buffer.from(buf.buffer).toString('hex');
+  assert.notStrictEqual(before, after);
+  assert.deepStrictEqual(before.slice(0, 4), after.slice(0, 4));
+  assert.deepStrictEqual(before.slice(-4), after.slice(-4));
+}
+
+{
+  const buf = new Uint32Array(10);
+  const before = Buffer.from(buf.buffer).toString('hex');
+  crypto.randomFillSync(buf, 1, 8);
+  const after = Buffer.from(buf.buffer).toString('hex');
+  assert.notStrictEqual(before, after);
+  assert.deepStrictEqual(before.slice(0, 8), after.slice(0, 8));
+  assert.deepStrictEqual(before.slice(-8), after.slice(-8));
+}
+
+{
+  const buf = new Uint16Array(10);
+  const before = Buffer.from(buf.buffer).toString('hex');
+  crypto.randomFill(buf, 1, 8, common.mustSucceed((buf) => {
+    const after = Buffer.from(buf.buffer).toString('hex');
+    assert.notStrictEqual(before, after);
+    assert.deepStrictEqual(before.slice(0, 4), after.slice(0, 4));
+    assert.deepStrictEqual(before.slice(-4), after.slice(-4));
+  }));
+}
+
+{
+  const buf = new Uint32Array(10);
+  const before = Buffer.from(buf.buffer).toString('hex');
+  crypto.randomFill(buf, 1, 8, common.mustSucceed((buf) => {
+    const after = Buffer.from(buf.buffer).toString('hex');
+    assert.notStrictEqual(before, after);
+    assert.deepStrictEqual(before.slice(0, 8), after.slice(0, 8));
+    assert.deepStrictEqual(before.slice(-8), after.slice(-8));
+  }));
+}
+
+{
+  // randomFill() with an offset and no size must not throw for types
+  // without a .length property, matching randomFillSync().
+  crypto.randomFill(new ArrayBuffer(10), 2, common.mustSucceed());
+  crypto.randomFill(new DataView(new ArrayBuffer(10)), 2, common.mustSucceed());
+}
+
 {
   [
     Buffer.alloc(10),