Update emscripten to version 3

[paulocoutinhox]

Hi,

I need some help to update this project to use Emscripten version 3+.

I already make the port in the branch: https://github.com/paulocoutinhox/pdfium-lib/tree/emscripten.

But when i try load any PDF, it throws this error:

Related code:

console.log('INIT 1');
FPDF.Init();   // <- here is the problem
console.log('INIT 2');

Can anyone help me debug/understand?

Thanks.

[paulocoutinhox]

Hi guys,

@cetinsert @Priestch @quincarter can you try help me finish it when you have time?

Thanks.

[quincarter]

I'll see if i can do something with this. I'll play with this over the weekend.

[jerbob92]

@paulocoutinhox I'm also looking into this. The main problem seems to be the memory allocator. PDFium uses ASLR but Emscripten 3 does not support giving a hint address when calling mmap, which is needed to do ASLR. See https://github.com/emscripten-core/emscripten/blob/1bbb5f8dea4422768bdc9a9a44ce8a9eb6dd39c9/system/lib/libc/emscripten_mmap.c#L119

I'm working on creating a standalone WASM build so that we can use it in a Go runtime, and so far it's not going too well :crying_cat_face: New problems every step of the way.

We could look into disabling ASLR in PDFium so that it can call mmap and allocate the memory pages it needs.

[paulocoutinhox]

Hi,

I will refactor all and remake a lot of things in this project. And when i start it, i will change this too.

Im only finishing another open source project that is a requirement for me.

Stay tuned here and feel free to donate to help project development.

Thanks.

[jerbob92]

Hi @paulocoutinhox,

I'm just curious, but what are your plans regarding this ticket and the remake? Because I really want to get this WASM pdfium build to work correctly, but the way I'm seeing it now, it totally depends on someone making a patch for pdfium to fix up the memory allocation, and it doesn't really have to do with this or any other pdfium build project.

[jerbob92]

@paulocoutinhox check this out: https://github.com/bblanchon/pdfium-binaries/issues/28#issuecomment-1293957584

[paulocoutinhox]

Hi,

All problems was fixed in new release.

You can check here: https://github.com/paulocoutinhox/pdfium-lib/releases/tag/5407

The demo is here: https://pdfviewer.github.io/

Feel free to donate to help project development.

Thanks.