Crash when CGO_ENABLED=1 while using WebviewBrowserPath option.

[fire988]

Description

when CGO_ENABLED set to 1, and load webview in custom location using WebviewBrowserPath, the output binary executable file is buggy, It will crash at GetAvailableCoreWebView2BrowserVersionString function.

To Reproduce

none

Expected behaviour

when CGO_ENABLED set to 1, and load webview in custom location using WebviewBrowserPath, the output binary executable file is buggy, It will crash at GetAvailableCoreWebView2BrowserVersionString function.

Screenshots

none

Attempted Fixes

No response

System Details

Wails CLI v2.0.0-beta.38


Scanning system - Please wait (this may take a long time)...Done.

System
------
OS:             Windows 10 Pro
Version:        2009 (Build: 19044)
ID:             21H2
Go Version:     go1.17.11
Platform:       windows
Architecture:   amd64

Wails
------
Version:        v2.0.0-beta.38

Dependency      Package Name    Status          Version
----------      ------------    ------          -------
WebView2        N/A             Available
npm             N/A             Installed       8.1.2
*upx            N/A             Installed       upx 3.96
*nsis           N/A             Available

* - Optional Dependency

Diagnosis
---------
Your system has missing dependencies!

Required package(s) installation details:
  - WebView2 : Available at https://developer.microsoft.com/en-us/microsoft-edge/webview2/

Optional package(s) installation details:
  - nsis : Available at https://nsis.sourceforge.io/Download

Additional context

No response

[leaanthony]

Thanks for opening this. Please provide minimal steps to reproduce. Thanks 🙏

[fire988]

STEPS:
under windows.

1. wails init a hello world project.

2. modify the main function in main.go file,like below:
   func main() {
   // Create an instance of the app structure
   app := NewApp()

   // Create application with options
   err := wails.Run(&options.App{
   Title: "webview-test",
   Width: 1024,
   Height: 768,
   DisableResize: false,
   Fullscreen: false,
   Frameless: false,
   StartHidden: false,
   HideWindowOnClose: false,
   RGBA: &options.RGBA{255, 255, 255, 255},
   Assets: assets,
   LogLevel: logger.DEBUG,
   OnStartup: app.startup,
   OnDomReady: app.domReady,
   OnShutdown: app.shutdown,
   Bind: []interface{}{
   app,
   },
   // Windows platform specific options
   Windows: &windows.Options{
   WebviewIsTransparent: false,
   WindowIsTranslucent: false,
   DisableWindowIcon: false,
   WebviewBrowserPath: "path/to/webview2/",
   },
   })

   if err != nil {
   log.Fatal(err)
   }
   }

3. Set enviroment variable CGO_ENABLED to 1

4. wails build

5. run it

[stffabi]

Would it be possible for you to also post the stacktrace of the panic?

You need to compile the binary with 'wails build --debug' to get the stacktrace shown in the console. That would be awesome 🙏

[NanoNik]

This is an issue in manual mapping of WebView2Loader.dll, probably something going wrong with TLS, as it is used inside GetAvailableCoreWebView2BrowserVersionString, if library loaded from disk, everything works fine. (This happens only with GetAvailableCoreWebView2BrowserVersionString)

[leaanthony]

I'm thinking we might need more docs around this feature in the guide section? Thoughts?

[stffabi]

I wonder if it is related to the wrong handling of unsafe.Pointer to uint64 of the webview2loader when loading from the embedded version, e.g here

wails/v2/internal/frontend/desktop/windows/go-webview2/webviewloader/module.go

Line 76 in 743d7cc

uint64(uintptr(unsafe.Pointer(browserPath))),

Normally native calls use uintptr with the uintptrescape compiler directive and not uint64 and maybe activating cgo has some side effects which trigger a stackgrow or something else.

@NanoNik do you have a stack trace of the panic?

I might find some time to investigate it over the weekend.

[NanoNik]

@stffabi No panics, function just returns ERROR_SUCCESS. Actually, I met this issue without using CGO, but it was on Windows 7.

[fire988]

Sorry, the information I provided was incorrect and is corrected as follows:

A cgo.go file needs to be created in the root of the project with the following contents:
package main

/*
#include <stdio.h>

int printint(int v) {
printf("printint: %d\n", v);
if (v==1)
return 1;
return v+printint(v-1);
}
*/
import "C"

func ctest() {
v := 100
n := C.printint(C.int(v))
println(n)
}

Then the bug can be triggered, the output after adding the --debug compile option is as follows:

---- WARNING ----
2022/07/16 13:22:04 Unable to call GetAvailableCoreWebView2BrowserVersionString (80070032): The operation completed successfully.

the program terminated with no panic.

[stffabi]

The error code implies that something is not supported. There's one issue on the webview2feedback repo which also mentions this error code when using a fixed version deployment and a relative path to the runtime MicrosoftEdge/WebView2Feedback#2025

Are you using a relative path?

Just to make sure I understand you correctly, the very same code with 'CGO_ENABLED=0' work just fine?

[leaanthony]

I've asked Champnic for an update on the linked bug in Webview2 👍

[fire988]

The error code implies that something is not supported. There's one issue on the webview2feedback repo which also mentions this error code when using a fixed version deployment and a relative path to the runtime MicrosoftEdge/WebView2Feedback#2025

Are you using a relative path?

Just to make sure I understand you correctly, the very same code with 'CGO_ENABLED=0' work just fine?

This problem has nothing to do with whether relative paths are used or not.

As long as the C code is not called, there is no problem.

I have done the following test:

1. create a .go file and set it's content only two lines:
   package main
   import "C"
2. set CGO_ENABLED to 1
3. the bug triggered.
4. set CGO_ENABLED to 0
5. It works fine.

[stffabi]

@fire988 Thanks for clarifying 🙏. I'll take a deeper look into it over the weekend.

[leaanthony]

Yeah, I'm not sure why Windows returns ERROR_SUCCESS for that method when clearly it's a "Not Supported" error. Very weird.

[stffabi]

I was able to reproduce it and it really appears as soon as cgo is used.
I can also confirm what @NanoNik stated, it only manifests when loading the Webview2Loader.dll from memory. Loading it from disk works as expected (using the normal loading process).It's also only a problem for getting the Version String function, skipping it and just try to load the Webview2 works also.

So it's some side effect of cgo in combination with the memory loader https://github.com/jchv/go-winloader

Maybe @jchv has an idea what is going on.

[stffabi]

There's a draft PR #1790 up for fixing this issue. Would it be possible for you @fire988 to give it a try? That would be awesome.

[leaanthony]

@fire988 Master now has the fixes for this. Please test using this guide. If it doesn't work as expected, please reopen 👍

[fire988]

I've done a full test and the problem has been solved, great!

[stffabi]

Awesome thanks for taking your time and testing it 🙏