We are currently migrating Bugzilla to GitHub issues.
Any changes made to the bug tracker now will be lost, so please do not post new bugs or make changes to them.
When we're done, all bug URLs will redirect to their equivalent location on the new bug tracker.

Bug 2139 - SDL_CreateWindow/WIN_GL_LoadLibrary fails due to external iconv not being able to convert path
Summary: SDL_CreateWindow/WIN_GL_LoadLibrary fails due to external iconv not being abl...
Status: RESOLVED FIXED
Alias: None
Product: SDL
Classification: Unclassified
Component: *don't know* (show other bugs)
Version: 2.0.0
Hardware: x86 Windows (All)
: P2 minor
Assignee: Sam Lantinga
QA Contact: Sam Lantinga
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2013-10-08 05:15 UTC by Jānis Rūcis
Modified: 2013-10-18 07:14 UTC (History)
0 users

See Also:


Attachments

Note You need to log in before you can comment on or make changes to this bug.
Description Jānis Rūcis 2013-10-08 05:15:39 UTC
Brief history:

We recently ported a game from SDL 1.2 to SDL 2. While doing Windows testing, I soon discovered that the game exits without opening a window with my cross-compiled SDL2.dll, but works great with the SDL2.dll from the MinGW SDK on libsdl.org. It was as simple as swapping out the DLLs to make it work.

Running the game in Wine showed that the game actually does run, up until the call to SDL_CreateWindow, which fails and leads the game to print out an error:

Failure to create window (LoadLibrary("OPENGL32.DLL"): (null))

Which basically says that there was no error, but maybe that's a Wine quirk.

The error string originates in SDL_windowsopengl.c, in WIN_GL_LoadLibrary, which contains this piece of code:

    wpath = WIN_UTF8ToString(path);
    _this->gl_config.dll_handle = LoadLibrary(wpath);
    SDL_free(wpath);
    if (!_this->gl_config.dll_handle) {
        char message[1024];
        SDL_snprintf(message, SDL_arraysize(message), "LoadLibrary(\"%s\")",
                     path);
        return WIN_SetError(message);
    }

After some digging, I discovered the culprit: WIN_UTF8ToString returns NULL. Why? Because it calls iconv_open from an iconv.dll that does not support the UCS-2-INTERNAL encoding. Why does the official SDL2.dll work? Because it calls no external iconv functions at all.

It turns out that the Fedora MinGW infrastructure (from which I obtained the conventiently prebuilt iconv.dll) does not provide a DLL from libiconv, but instead provides a DLL from a minimal Windows library called win-iconv. Which knows a good bit, but doesn't know anything about UCS-2-INTERNAL:

http://code.google.com/p/win-iconv/source/browse/trunk/win_iconv.c#155

So there are two problems here:

1) The error message is clearly useless, because LoadLibrary is an innocent bystander. Instead wpath should probably checked for NULL, and a more appropriate error should be set. Ideally something that makes it clear than an external iconv is causing trouble.
2) SDL doomed itself at the ./configure step, by finding an existing iconv and happily using it without confirming support for the mandatory encodings required by SDL.

There are certainly a few easy ways out of the situation (although I didn't yet manage to figure out how to prevent ./configure from looking for external iconv), but this had me completely stomped for a good while, so I figured it's worth writing down if anything.

(Search also found this, which talks a little about using UTF-16LE instead of UCS-2-INTERNAL: https://bugzilla.libsdl.org/show_bug.cgi?id=2075)
Comment 1 Sam Lantinga 2013-10-18 07:14:52 UTC
This should be fixed, in your case.  Thanks for the detailed investigation!
http://hg.libsdl.org/SDL/rev/b4a9cc7085f2