Apply suggestions from code review

Co-authored-by: Antoine du Hamel <[email protected]>

Author: jasnell

lib/buffer.js

@@ -355,23 +355,19 @@ Buffer.copyBytesFrom = function copyBytesFrom(view, offset, length) {
   if (offset !== undefined || length !== undefined) {
     if (offset !== undefined) {
       validateInteger(offset, 'offset', 0);
+      if (offset >= viewLength) return Buffer.alloc(0);
     } else {
       offset = 0;
     }
+    let end;
     if (length !== undefined) {
       validateInteger(length, 'length', 0);
+      end = offset + length;
     } else {
-      length = viewLength;
+      end = viewLength;
     }
 
-    offset = MathMin(offset, viewLength);
-    length = MathMin(length, viewLength - offset);
-
-    if (length === 0) {
-      return Buffer.alloc(0);
-    }
-
-    view = TypedArrayPrototypeSlice(view, offset, offset + length);
+    view = TypedArrayPrototypeSlice(view, offset, end);
   }
 
   return fromArrayLike(new Uint8Array(

test/parallel/test-buffer-from.js

@@ -95,13 +95,47 @@ Buffer.from('deadbeaf', 'hex'); // Should not throw.
 }
 
 throws(() => {
-  Buffer.copyBytesFrom('nope');
+  Buffer.copyBytesFrom();
 }, {
   code: 'ERR_INVALID_ARG_TYPE',
 });
 
-throws(() => {
-  Buffer.copyBytesFrom(new Uint8Array(1), 'a');
-}, {
-  code: 'ERR_INVALID_ARG_TYPE',
-});
+['', Symbol(), true, false, {}, [], () => {}, 1, 1n, null, undefined].forEach(
+  (notTypedArray) => throws(() => {
+    Buffer.copyBytesFrom('nope');
+  }, {
+    code: 'ERR_INVALID_ARG_TYPE',
+  })
+);
+
+['', Symbol(), true, false, {}, [], () => {}, 1n].forEach((notANumber) =>
+  throws(() => {
+    Buffer.copyBytesFrom(new Uint8Array(1), notANumber);
+  }, {
+    code: 'ERR_INVALID_ARG_TYPE',
+  })
+);
+
+[-1, NaN, 1.1, -Infinity].forEach((outOfRange) =>
+  throws(() => {
+    Buffer.copyBytesFrom(new Uint8Array(1), outOfRange);
+  }, {
+    code: 'ERR_OUT_OF_RANGE',
+  })
+);
+
+['', Symbol(), true, false, {}, [], () => {}, 1n].forEach((notANumber) =>
+  throws(() => {
+    Buffer.copyBytesFrom(new Uint8Array(1), 0, notANumber);
+  }, {
+    code: 'ERR_INVALID_ARG_TYPE',
+  })
+);
+
+[-1, NaN, 1.1, -Infinity].forEach((outOfRange) =>
+  throws(() => {
+    Buffer.copyBytesFrom(new Uint8Array(1), 0, outOfRange);
+  }, {
+    code: 'ERR_OUT_OF_RANGE',
+  })
+);