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List:       kde-devel
Subject:    Re: [PATCH] second try at fixing up socklen issues on Solaris
From:       Oswald Buddenhagen <ob6 () inf ! tu-dresden ! de>
Date:       2001-04-05 11:50:04
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> I can't imagine why any OS should use more than sizeof(int) bytes for
> socklen_t, but who knows?
>
me knows:
quoting the accept(2) man page on linux (so even the last person
on this list understands, what this thread is all about ...):

       The third argument of accept was originally declared as an
       `int *' (and is that under libc4 and  libc5  and  on  many
       other systems like BSD 4.*, SunOS 4, SGI); a POSIX 1003.1g
       draft standard wanted to change it into a `size_t *',  and
       that  is  what it is for SunOS 5.  Later POSIX drafts have
       `socklen_t *', and so do the Single Unix Specification and
       glibc2.  Quoting Linus Torvalds: _Any_ sane library _must_
       have "socklen_t" be the same size as int.   Anything  else
       breaks  any BSD socket layer stuff.  POSIX initially _did_
       make it a size_t, and I (and hopefully others,  but  obvi-
       ously not too many) complained to them very loudly indeed.
       Making it a size_t is completely broken,  exactly  because
       size_t  very  seldom  is  the same size as "int" on 64-bit
       architectures, for example.  And it _has_ to be  the  same
       size as "int" because that's what the BSD socket interface
       is.  Anyway, the POSIX people eventually got a  clue,  and
       created  "socklen_t".   They  shouldn't have touched it in
       the first place, but once they did they  felt  it  had  to
       have  a  named type for some unfathomable reason (probably
       somebody didn't like losing  face  over  having  done  the
       original stupid thing, so they silently just renamed their
       blunder).

so the only acceptable solution seems to be the one i already presented:
- export interfaces using "[unsigned] int"
- internally use "socklen_t", which is #defined to 
  typeof("actual-socklen_t"), if no native typedef is found by configure

don't use any ksize_t or ksocklen_t - that's only unnecessary clutter.

> My current problem is that AIX uses unsigned long instead of
> unsigned int in 32 bit mode, probably for backward compatibility.
>
is sizeof(long) == sizeof(size_t) != sizeof(int) on your system?
if so, it's one of the broken-posix systems.

> But is it guaranteed by any standard that socklen_t is a basic data
> type everywhere?
> 
no. "real" socklen_t is a typedef and therefore no basic type (at least
according to the definition of "basic data type" i know). behind the
curtain it's of course an int (good) or size_t (bad).

best regards

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