FS Nodes: Execute bit erroneously checked on read property

[jvilk]

The problem is here: https://github.com/kripken/emscripten/blob/incoming/src/library_fs.js#L183

I have a node for a file with the octal mode 100644, which should be globally readable. However, the read mask includes the execute bit for some reason, causing the read property on the file's node to be false.

This property is checked in the SDL library before it dynamically loads a (non-preloaded) audio file: https://github.com/kripken/emscripten/blob/incoming/src/library_sdl.js#L1932

Is this a bug, or is there some reason why the Emscripten FS requires the execute bit before it can read a file (perhaps because the execute bit is required to list directory contents)?

[inolen]

It's part of the legacy FS code. That bit for whatever reason was set on any node created with the canRead flag, possibly due to reading directories as you mentioned.

The real solution would be to migrate whatever is depending on the old interfaces over to the new ones (https://github.com/kripken/emscripten/wiki/Filesystem-API).

Are these files being loaded through the built in preload?

[jvilk]

No. My project BrowserFS emulates the Node FS API in the browser, and I created an Emscripten FS object based off of NODEFS for it.

Are you saying that the read property itself is a legacy property, and that the solution is to refactor the code that uses it?

[inolen]

Yup.

try {
    bytes = FS.readFile(filename);
} catch (e) {
    Module.printErr('Couldn\'t find file for: ' + filename);
    return 0;
}

...

var blob = new Blob([bytes], {type: rwops.mimetype});

looks somewhat correct from a quick look.

[jvilk]

OK. Thanks for the pointers. I'll implement, test, and submit a PR.

[inolen]

I believe this is fully resolved with the merged pr.

Thanks for taking the time on this.