Re: [MinGW] RFC/RFA: Get Partial Stack Traces on Windows

[Bryce McKinlay <mckinlay at redhat dot com>]

Ranjit Mathew wrote:
> There is no manual page for dladdr() on my system (though
> there are for dlopen(), dlsym(), etc.) and online searches
> didn't help much. Are the names not dynamically allocated
> on all systems? I mean, is free() in this case non-kosher
> on just glibc systems or is it the case for Solaris, etc.
> as well?
>   

Yes, there does seem to be a lack of docs for dladdr(). But, I found this:

http://techpubs.sgi.com/library/tpl/cgi-bin/getdoc.cgi?coll=0650&db=man&fname=/usr/share/catman/p_man/cat3/libdl/dladdr.z

In particular:
"The memory pointed to by *dli_fname* and *dli_sname* is within the 
mapped object. If the object is closed with *dlclose()*, the pointers 
become invalid."

So, its safe to assume you don't need a free().
> Anyway, adding the "const" qualifiers and removing the
> misguided free() calls make things work again on Linux.
> I'm attaching the latest revision of this patch.
>
> OK to apply?
>
> Thanks,
> Ranjit.
>
> - --
> Ranjit Mathew      Email: rmathew AT gmail DOT com
>
> Bangalore, INDIA.    Web: http://rmathew.com/
>
>   
> ------------------------------------------------------------------------
>
> Index: ChangeLog
> from  Ranjit Mathew  <rmathew@gcc.gnu.org>
>
> 	* gcj/javaprims.h (_Jv_uintptr): New typedef similar to uintptr_t in
> 	C99.
>   

Hmm, is there some reason we can't just use uintptr_t? Doesn't GCC 
ensure it is always available?
> 	* include/java-stack.h: Include stdlib.h.
> 	(_Jv_AddrInfo): New structure to hold address information.
> 	(_Jv_platform_dladdr): Declare.
> 	* posix.cc: Include dlfcn.h if available.  Include java-stack.h.
> 	(_Jv_platform_dladdr): Define.
> 	* win32.cc: Include string.h.  Include java-stack.h.
> 	(backtrace): Remove.
> 	(_Jv_platform_dladdr): Define.
>   

Cool. Splitting out _Jv_platform_dladdr really cleans up the 
stacktrace.cc code - this looks perfect, almost - stylistically I think 
it would be better to declare _Jv_platform_dladdr in platform.h along 
with the other _Jv_platform_* functions. I realize this means platform.h 
will have to typedef _Jv_AddrInfo, or include java-stack.h, but I don't 
think that is a significant problem.

Otherwise, this is ok to commit. TVM!

Bryce