fix: extend with null bytes when calling truncate with a len grea…

…ter than the current file size (#875)

* fix: truncate to larger size

* chore: add missing semicolon

src/__tests__/promises.test.ts

@@ -193,6 +193,8 @@ describe('Promises API', () => {
  const fileHandle = await promises.open('/foo', 'r+');
  await fileHandle.truncate(5);
  expect(vol.readFileSync('/foo').toString()).toEqual('01234');
+ await fileHandle.truncate(7);
+ expect(vol.readFileSync('/foo').toString()).toEqual('01234\0\0');
  await fileHandle.close();
  });
  it('Reject when the file handle was closed', async () => {
@@ -592,6 +594,8 @@ describe('Promises API', () => {
  it('Truncate an existing file', async () => {
  await promises.truncate('/foo', 5);
  expect(vol.readFileSync('/foo').toString()).toEqual('01234');
+ await promises.truncate('/foo', 7);
+ expect(vol.readFileSync('/foo').toString()).toEqual('01234\0\0');
  });
  it('Reject when file does not exist', () => {
  return expect(promises.truncate('/bar')).rejects.toBeInstanceOf(Error);

src/__tests__/volume.test.ts

@@ -955,6 +955,13 @@ describe('volume', () => {
  vol.truncateSync('/1', 2);
  expect(vol.readFileSync('/1', 'utf8')).toBe('12');
  });
+ it('Larger truncate', () => {
+ const fd = vol.openSync('/2', 'w');
+ vol.writeFileSync(fd, '12345');
+ expect(vol.readFileSync('/2', 'utf8')).toBe('12345');
+ vol.truncateSync('/2', 10);
+ expect(vol.readFileSync('/2', 'utf8')).toBe('12345\0\0\0\0\0');
+ });
  });
  describe('.truncate(path[, len], callback)', () => {
  xit('...', () => {});

src/node.ts

@@ -143,9 +143,10 @@ export class Node extends EventEmitter {
  if (len <= this.buf.length) {
  this.buf = this.buf.slice(0, len);
  } else {
- const buf = bufferAllocUnsafe(0);
+ const buf = bufferAllocUnsafe(len);
  this.buf.copy(buf);
- buf.fill(0, len);
+ buf.fill(0, this.buf.length);
+ this.buf = buf;
  }
  }