On 12/02/2016 01:42 AM, Mark Wielaard wrote: > Hi, > > Someone was porting elfutils libelf to Windows64 and noticed that the > return types of gelf_newehdr and gelf_newphdr (unsigned long int) is not > appropriate on that platform. It uses the LLP64 data model where int and > long are both 32bits, while pointers are 64bits. Instead of the more > common LP64 model where both long and pointer are 64bits. This obviously > breaks that interface. > > I couldn't find the history behind this return type. Both elfutils and > solaris libelf share the same return type, but some other libelf > implementations, like the freebsd one, return a void *. Which does make > more sense IMHO. Does someone remember the background? > > I have been pondering just changing the return type to void *, which > should be abi compatible on any platform that elfutils currently > supports. But it might cause some compiler warnings about needed or > unneeded casts when existing code relies on the the return type being an > integral type. So an alternative would be to make the functions return > an uintptr_t, which should work in all data models.
I'd favor uintptr_t to keep better compatibility with current elfutils. That's not perfect either, since glibc uses "unsigned int" on 32-bit platforms, so that could still cause warnings for things that strictly expect long, like printf "%lx". But directly printing a newehdr return value (without saving it somewhere) is a weird thing to do, so I think we can dismiss that case, at least. Off the top of my head, I can't think of anything else that's so strict about long vs. int. Another option is to make the change conditional on __LP64__, so existing platforms are totally unaffected. I'd still lean toward uintptr_t for the new case, so existing libelf code can port easily. > Any opinions if this is something to clarify/fix across > implementations/platforms supporting an libelf implementation? > > Thanks, > > Mark > _______________________________________________ > elfutils-devel mailing list -- [email protected] > To unsubscribe send an email to [email protected] > _______________________________________________ elfutils-devel mailing list -- [email protected] To unsubscribe send an email to [email protected]
