Re: [Bug: 21.5-b27] Can't move cursor in edit-faces buffer

Ron Isaacson wrote: Ok, got some more details on this. The coredump was completely unusable, but gdb helped narrow it down to two problems which converged with unfortunate results: 1. We build most software with minimal dependencies on /usr/lib, so it works across OS releases. For example, libpng comes from a central location, and we have a build wrapper that sets CPPFLAGS to include -I/our/path/to/libpng, and also -L and -Wl,-rpath. In our args to xemacs's configure, we also use: --with-cppflags=-idirafter/usr/include/wnn along with lots of other craziness to get wnn to work correctly. Unfortunately, --with-cppflags REPLACES the contents of the inherited CPPFLAGS, instead of appending to it. So we end up without our central include paths in CPPFLAGS at compile-time, and we pick up lots of header files from /usr, while getting the matching libs from our central location at build-time & runtime. 2. Because of the above, at runtime, png_create_read_struct (glyphs-eimage.c:875) throws an error ("Incompatible libpng version in application and library"). This gets passed to the error handler, png_ptr->error_fn, which points to png_error_func (glyphs-eimage.c:821). This function, in turn, does a longjmp to png_err_stct.setjmp_buffer. The problem is that the setjmp_buffer in the png_err_stct lexical struct isn't set until line 902. This is inside png_instantiate, but not until AFTER the call to png_create_read_struct, which is the function that throws the error! So at the time png_error_func gets called, setjmp_buffer contains 0. This explains why the corefile has no usable stack trace. You might argue that #1 is our problem, and that if you specify --with-cppflags, that's an override to the default behavior of inheriting CPPFLAGS. We've got an easy workaround for that, but it still might be something to consider. #2 is definitely not our problem. :-) I think you need to ensure that png_err_stct.setjmp_buffer is set to a valid address BEFORE passing png_error_func as a parameter to anything. Otherwise, any runtime error from png_create_read_struct will get you into the same boat. -- Ron Isaacson Morgan Stanley ron.isaacson(a)morganstanley.com / (212) 276-0268 NOTICE: If received in error, please destroy and notify sender. Sender does not waive confidentiality or privilege, and use is prohibited. _______________________________________________ XEmacs-Beta mailing list XEmacs-Beta(a)xemacs.org http://calypso.tux.org/cgi-bin/mailman/listinfo/xemacs-beta