emscripten has slightly odd default values for some environment variables

[absmall]

emscripten sets some default values for environment variables:
// Set default values. Use string keys for Closure Compiler compatibility.
ENV['USER'] = 'root';
ENV['PATH'] = '/';
ENV['PWD'] = '/';
ENV['HOME'] = '/home/emscripten';
ENV['LANG'] = 'en_US.UTF-8';
ENV['_'] = './this.program';

The default values for HOME and LANG are not what I would have expected. For LANG, it seems strange to default to English - I happen to speak English, but I would not expect this is a reasonable default for all users of programs compiled with emscripten - would "C" make more sense? It's a bit more neutral. For HOME, this is a directory that is not very likely to exist. Would "/" make more sense?

[kripken]

Good points.

HOME might as well be "/", unless we think it might break something.

Is "C" a valid value for LANG? If so, sounds fine to me.

cc @juj

[juj]

C is a valid value for LANG, and represents the POSIX locale: http://pubs.opengroup.org/onlinepubs/009695399/basedefs/xbd_chap07.html#tag_07_02

That chapter says For C-language programs, the POSIX locale shall be the default locale when the setlocale() function is not called. so perhaps we should indeed be setting those to C for proper conformance?

[juj]

I'm not sure about HOME=/, since I can think for a number of applications that might assume some kind of unix-y filesystem with /dev/ etc. We currently create /dev/random and a few others for all applications. Should we perhaps create the directory /home/emscripten/ for all applications as well?

[b-spencer]

Perhaps simply HOME=/home would suffice?

Well behaved POSIX programs shouldn't really be assuming what kind of directory tree their $HOME directory is actually in, but I can see them wanting a separate directory from /.

[absmall]

Or possibly "/root". The user is root, and I think /root is a more common home directory for root.

Or alternatively, maybe USER should be emscripten, and HOME should be /home/emscripten (and either way, I think the directory $HOME points to should exist.)

[b-spencer]

I agree with absmall.

[kripken]

cc @sunfishcode

[sunfishcode]

Ok, here's a pull request here which proposes "web_user" as the username (though the uid is still 0, for what that's worth). It sets HOME to /home/web_user, and arranges for that path to exist. It also sets LANG=C as discussed above. I also updated _ to make it consistent with argv[0].

sunfishcode@e543e1b

Thoughts?

[kripken]

Looks good, let's discuss details in the pull. Closing this.

[alecazam]

I can't seem to get toupper/tolower to work in Emscripten, but haven't delved too deeply yet. I don't think setting a non UTF-8 default was great for developers. I set the locale, and that doesn't help either with my test case (although this code works on OSX).

We had UTF8 code that was expecting these routines to just work. Try the following with and without setlocale called. This is Cyrllic A converted to lowercase A, and vice versa.

setlocale(LC_ALL, "en_US.UTF-8");

int upperCaseA = 0x0410;
int lowerCaseA = 0x0430;
ASSERT(lowerCaseA == tolower(upperCaseA));
ASSERT(toupper(lowerCaseA) == upperCaseA);

[alecazam]

I should add this is with Emscripten 1.36.1

[alecazam]

It turns out that even after setting the locale to UTF-8, that Emscripten's toupper/tolower still don't work, so we'll have to roll our own solution here instead of using those.