Re: [Libguestfs] Note regarding bin2s.pl

On 12.01.2016 12:10, Richard W.M. Jones wrote: > On Tue, Jan 12, 2016 at 10:05:00AM +0000, Richard W.M. Jones wrote: >> On Tue, Jan 12, 2016 at 07:57:03AM +0100, Hilko Bengen wrote: >>> Helge, >>> >>> I have applied all the architecture-specific bits but not the bin2s >>> script yet. TBH, so far I don't see what is wrong about export and use >>> of the "_binary_init_size" constant. >> >> [https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=809185] >> >> I see it as a reasonable simplification - it allows us to get rid of >> that conditional code for HP-UX in bin2s.pl. >> >> However looking at the patch, I don't like the casts in: >> >> - size_t n = (size_t) &_binary_init_size; >> + size_t n = ((size_t) &_binary_init_end) - ((size_t) &_binary_init_start); >> >> Since those are pointers, it seems better to simply subtract them. >> (Though it would be better if we'd declared the type of >> _binary_init_start/_end as uint8_t instead of char.) >> >> If we must cast them then the correct integer to use is 'intptr_t', an >> int type that's guaranteed by C99 to be long enough to store a >> pointer. > > How about the attached patch? In general I'd say it looks OK. Just a few comments: -extern char _binary_init_start, _binary_init_end, _binary_init_size; +extern uint8_t _binary_init_start, _binary_init_end; Does the char to uint8_t change really makes such a big difference? We will just use the address of the variable anyway.

- size_t n = (size_t) &_binary_init_size; + size_t n = &_binary_init_end - &_binary_init_start; It's OK, but maybe some compilers/platforms might complain with a warning. It might be better to keep a cast to (size_t), e.g.: + size_t n = (size_t) (&_binary_init_end - &_binary_init_start);

But either way, I'm fine with both approaches. Thanks! Helge