Re: [Emacs-diffs] ImageMagick Support on Windows

[Alexander Shukaev]

Can you run this command under GDB, and see exactly where it crashes,
and why?

I, personally, usually don't use GDB to find out causes of crashing on Windows, i.e. I either infer them from the code or find it out through logging facilities. The main reason why I almost never use GDB on Windows is the following output:

Program received signal SIGSEGV, Segmentation fault.

0x0000000000000000 in ?? ()

which actually conveys no information at all. The crash often goes deep to some Windows system DLLs and therefore cannot be traced by GDB. This is exactly the case this time once again. We cannot rely on GDB now...

I'm not sure I see where image.el needs to load image libraries.

Could you point out where you think that happens?  (Running temacs
under GDB will surely tell, btw.)  If you rename the ImageMagick DLLs
to some other names, or remove them from PATH, does the Emacs build
succeed?

 

It should not necessarily load images. It can do some initialization stuff involving ImageMagick calls. For instance, I have already found that commenting out:

(imagemagick-register-types)

in the very bottom of "image.el" prevents the crash and "temacs.exe" continues to function properly.

Are you sure that you have pointed out all the spots that should be patched and that we didn't miss any of them? Please, since you know the internals better, think of what we could miss patching, it really feels like a zero pointer somewhere or something alike. In any case, now you know that it all starts from the "(imagemagick-register-types)" call.

Tomorrow I'm leaving for 2 weeks vacation, so I can continue only when I'm back. I'm still available today for discussions.