Run with Emscirpten: TypeError getRandomValue

[tbuchs]

I have a c++ framework which calls the libsodium function randombytes_buf. I want to port the framework using emscripten and compiled the library with ./dist-build/emscripten.sh —sumo. Then i compiled the framework and linked with -lsodium to libsodium.a.

However when running the resulting file in the browser I always get the error TypeError: Module.getRandomValue is not a function. I have seen that several other ppl had the same issue, but couldn‘t figure out how they solved it. Tried also adding sodium_init(), but didn‘t help. I have seen that there also exists libsodium.js, but couldn‘t figure out how to use it in C++.

[tbuchs]

I have found the problem in the js file generated of emscripten. The js file contains the following definition:
var ASM_CONSTS = {
594516: () => { return Module.getRandomValue(); },
594552: () => { if (Module.getRandomValue === undefined) { try { var window_ = 'object' === typeof window ? window : self; var crypto_ = typeof window_.crypto !== 'undefined' ? window_.crypto : window_.msCrypto; var randomValuesStandard = function() { var buf = new Uint32Array(1); crypto_.getRandomValues(buf); return buf[0] >>> 0; }; randomValuesStandard(); Module.getRandomValue = randomValuesStandard; } catch (e) { try { var crypto = require('crypto'); var randomValueNodeJS = function() { var buf = crypto['randomBytes'](4); return (buf[0] << 24 | buf[1] << 16 | buf[2] << 8 | buf[3]) >>> 0; }; randomValueNodeJS(); Module.getRandomValue = randomValueNodeJS; } catch (e) { throw 'No secure random number generator found'; } } } } };

The program calls the function at 594516 and fails with the error from above. However, if I change to the second definition, the call seems to work