[Debian-med-packaging] Bug#748305: Bug#748305: Unchecked conversion from double to enum

[Sascha Steinbiss]

Hi Michael,

thanks for your bug report! Let's see:

[...]
> Indeed reviewing the code here
> 
> http://sources.debian.net/src/genometools/1.5.1-3/src/gtlua/encseq_lua.c?hl=83#L83
> 
> and taking into account the definition of luaL_checknumber on the one hand and
> GtReadmode on the other:
> 
> http://sources.debian.net/src/genometools/1.5.1-2/src/external/lua-5.1.5/src/lauxlib.c?hl=176#L176
> http://sources.debian.net/src/genometools/1.5.1-2/src/core/readmode_api.h#L23
> 
> this conversion appears to be dangerous at best: if a double value is return
> that does not result in any of the int values 0, 1, 2, 3 all further code may
> break.

Yes, you are right. I think it would be best to adjust this interface to
either have multiple Lua methods for each readmode, each calling
gt_encseq_reader_reinit_with_readmode() with a correct literal readmode
value, or to implement proper error reporting. The readmode is typically
given directly in the call, not calculated using float arithmetics...
But anyway, it is possible to end up with wrong parameters here in
theory, and I will take care fix the problem.

I will add a patch to the package and GenomeTools itself. Is this the
only instance of such a problem or did your compiler just stop on the
first error? I could imagine such an issue could come up in other places
in the Lua bindings as well which could benefit from safer double-int
conversion...

> Best,
> Michael

Thanks,
Sascha