wasm file path issue

[Guillaume Rouault]

Hi, 

 I am very new to compiling, just trying to play with some C code ( very new to C also ) and compiling it to wasm.

I have been pretty successful so far : 

I have managed to compile some C code with :

emcc main.c -s WASM=1 --separate-asm -o build/aaa.html

My issue is : 

 when executing aaa.js with Node, it only works if I cd into the build/ directory, and I have the same issue when I try to include this into a web project.

I don't if the issue is with emcc , javascript or nodejs... 

To make it short, I'm a little lost ... 

node build/aaa.js //returs an error
cd build
node aaa.js //works fine

[Alon Zakai]

The JS needs to find the wasm file, and if it is in another directory it gets confused. I think by default we just look in the current dir, and let people customize that using

https://kripken.github.io/emscripten-site/docs/api_reference/module.html#Module.locateFile

I'm not sure if there's a way for the JS to say "is the wasm file in the same directory as me" (__file__ in C or Python) in a cross-environment way (web, node, JS shells), but if there were that would be good for us to use.

Another option is to use -s SINGLE_FILE=1 to create a single file for everything (but embedding the wasm in the JS is less efficient).

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[Guillaume Rouault]

Thank Alon, it's seems more logical now :) 

 I modified emcc  compile command like so :

emcc main.c -s WASM=1 --pre-js build/pre.js -o build/aaa.js

and I wrote this into the prej.js file :

var Module = {

    'locateFile' : 'build/aaa.wasm'

}

After compilation I can find this code was added to aaa.js

But I still get the same issue, that is : an error complaining that the wasm file should be found one directory up.

abort({"errno":-4058,"code":"ENOENT","syscall":"open","path":"D:\\CODE\\web_playground\\web_assembly\\c\\aaa.wasm"}) at Error

    at jsStackTrace (D:\CODE\web_playground\web_assembly\c\build\aaa.js:1004:13)

    at stackTrace (D:\CODE\web_playground\web_assembly\c\build\aaa.js:1021:12)

    at abort (D:\CODE\web_playground\web_assembly\c\build\aaa.js:2430:44)

    at getBinary (D:\CODE\web_playground\web_assembly\c\build\aaa.js:1531:7)

    at D:\CODE\web_playground\web_assembly\c\build\aaa.js:1550:15

    at new Promise (<anonymous>)

    at getBinaryPromise (D:\CODE\web_playground\web_assembly\c\build\aaa.js:1549:12)

    at instantiateArrayBuffer (D:\CODE\web_playground\web_assembly\c\build\aaa.js:1610:7)

    at doNativeWasm (D:\CODE\web_playground\web_assembly\c\build\aaa.js:1632:7)

    at Object.Module.asm (D:\CODE\web_playground\web_assembly\c\build\aaa.js:1712:15)

node.js exiting due to unhandled promise rejection

Am I doing it wrong ? 

Thanks a lot

[Guillaume Rouault]

Oups, 

 so Module.locateFile must be a method ( of course !!!): 

I modified the prej.js code 

var Module = {

    'locateFile' : function(wasmBinaryFile){ return 'build/aaa.wasm'}

}

And now it work as expected 

Thank you so much