"fs.writeFile" with mode 0o777 doesn't work as expected

[ysmood]

Sample code:

var fs;

fs = require('fs');

try {
  fs.unlinkSync('a');
} catch (_error) {}

fs.writeFileSync('a', 'ok', {
  mode: 0o777
});
console.log(fs.statSync('a').mode.toString(8));
// output => 0o755

fs.chmodSync('a', 0o777);
console.log(fs.statSync('a').mode.toString(8));
// output => 0o777

It should output 0o777. But I get 0o755.
If I use the fs.chmod to change mode, everything will go well.

[bnoordhuis]

That's the umask at work:

> (0o777 & ~process.umask()).toString(8)
'755'

Not a bug, it's just the way UNIX permissions work.

[ysmood]

@bnoordhuis But why chmod doesn't follow the umask?

[bnoordhuis]

@ysmood Because the umask applies to just a handful of functions (open, mkdir, etc.)