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fs: harden validation of start option in createWriteStream

PR-URL: #25579
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Sakthipriyan Vairamani <thechargingvolcano@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
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ZYSzys authored and lpinca committed Feb 10, 2019
1 parent e154176 commit 70f4f08a9f0902056ac47271f9d3a761fcee4715
Showing with 26 additions and 12 deletions.
  1. +8 −4 doc/api/fs.md
  2. +1 −7 lib/internal/fs/streams.js
  3. +17 −1 test/parallel/test-file-write-stream3.js
@@ -1470,9 +1470,11 @@ returned by this method has a default `highWaterMark` of 64 kb.

`options` can include `start` and `end` values to read a range of bytes from
the file instead of the entire file. Both `start` and `end` are inclusive and
start counting at 0. If `fd` is specified and `start` is omitted or `undefined`,
`fs.createReadStream()` reads sequentially from the current file position.
The `encoding` can be any one of those accepted by [`Buffer`][].
start counting at 0, allowed values are in the
[0, [`Number.MAX_SAFE_INTEGER`][]] range. If `fd` is specified and `start` is
omitted or `undefined`, `fs.createReadStream()` reads sequentially from the
current file position. The `encoding` can be any one of those accepted by
[`Buffer`][].

If `fd` is specified, `ReadStream` will ignore the `path` argument and will use
the specified file descriptor. This means that no `'open'` event will be
@@ -1548,7 +1550,8 @@ changes:
* Returns: {fs.WriteStream} See [Writable Stream][].

`options` may also include a `start` option to allow writing data at
some position past the beginning of the file. Modifying a file rather
some position past the beginning of the file, allowed values are in the
[0, [`Number.MAX_SAFE_INTEGER`][]] range. Modifying a file rather
than replacing it may require a `flags` mode of `r+` rather than the
default mode `w`. The `encoding` can be any one of those accepted by
[`Buffer`][].
@@ -4953,3 +4956,4 @@ the file contents.
[chcp]: https://ss64.com/nt/chcp.html
[inode]: https://en.wikipedia.org/wiki/Inode
[support of file system `flags`]: #fs_file_system_flags
[`Number.MAX_SAFE_INTEGER`]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number/MAX_SAFE_INTEGER
@@ -243,13 +243,7 @@ function WriteStream(path, options) {
this.closed = false;

if (this.start !== undefined) {
if (typeof this.start !== 'number') {
throw new ERR_INVALID_ARG_TYPE('start', 'number', this.start);
}
if (this.start < 0) {
const errVal = `{start: ${this.start}}`;
throw new ERR_OUT_OF_RANGE('start', '>= 0', errVal);
}
checkPosition(this.start, 'start');

this.pos = this.start;
}
@@ -161,6 +161,7 @@ function run_test_3() {
assert.strictEqual(fileData, fileDataExpected_3);

run_test_4();
run_test_5();
});

file.on('error', function(err) {
@@ -184,7 +185,22 @@ const run_test_4 = common.mustCall(function() {
const err = {
code: 'ERR_OUT_OF_RANGE',
message: 'The value of "start" is out of range. ' +
'It must be >= 0. Received {start: -5}',
'It must be >= 0 and <= 2 ** 53 - 1. Received -5',
type: RangeError
};
common.expectsError(fn, err);
});


const run_test_5 = common.mustCall(function() {
// Error: start must be <= 2 ** 53 - 1
const fn = () => {
fs.createWriteStream(filepath, { start: 2 ** 53, flags: 'r+' });
};
const err = {
code: 'ERR_OUT_OF_RANGE',
message: 'The value of "start" is out of range. ' +
'It must be >= 0 and <= 2 ** 53 - 1. Received 9007199254740992',
type: RangeError
};
common.expectsError(fn, err);

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