fs: fix default length parameter for fs.read

Currently, specifying an `offset` without a `length`
throws an `ERR_OUT_OF_RANGE` error.
This commit provides a more sensible default.
This change should only affect cases
where no length is specified and a nonzero offset is,
which are currently throwing errors.

PR-URL: nodejs#40349
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>

doc/api/fs.md

@@ -392,7 +392,7 @@ added:
   * `offset` {integer} The location in the buffer at which to start filling.
     **Default:** `0`
   * `length` {integer} The number of bytes to read. **Default:**
-    `buffer.byteLength`
+    `buffer.byteLength - offset`
   * `position` {integer} The location where to begin reading data from the
     file. If `null`, data will be read from the current file position, and
     the position will be updated. If `position` is an integer, the current
@@ -3119,7 +3119,7 @@ changes:
 * `options` {Object}
   * `buffer` {Buffer|TypedArray|DataView} **Default:** `Buffer.alloc(16384)`
   * `offset` {integer} **Default:** `0`
-  * `length` {integer} **Default:** `buffer.byteLength`
+  * `length` {integer} **Default:** `buffer.byteLength - offset`
   * `position` {integer|bigint} **Default:** `null`
 * `callback` {Function}
   * `err` {Error}

lib/fs.js

@@ -621,7 +621,7 @@ function read(fd, buffer, offset, length, position, callback) {
     ({
       buffer = Buffer.alloc(16384),
       offset = 0,
-      length = buffer.byteLength,
+      length = buffer.byteLength - offset,
       position
     } = options);
   }