On Thu, Jan 16, 2020 at 06:48:30AM -0700, Raymond, David wrote:
> Hmm....
>
> Thought I found a 2^15 -1 version of SSIZE_MAX in the includes, but I
> guess I was mistaken.
>
> The real issue is whether doing write(2) to a TCP/IP socket bigger
> than 2^15 - 1 bytes causes problems. I am not very experienced in
> this area.
It should not. But short read and writes are a real thing and code
should take care, see the example in write(2).
-Otto
>
> Dave Raymond
>
> On 1/15/20, Bryan Steele <[email protected]> wrote:
> >> I am confused about SSIZE_MAX and read(2)/write(2). The POSIX
> >> SSIZE_MAX is something like 2^15 -1. This seems to be a real
> >> limitation when writing to a TCP/IP socket, as I learned from
> >> experience. However, much larger reads and writes seem to be possible
> >> to files and UNIX sockets (pipes). This makes me uneasy, given the
> >> warning in the man pages for read(2)/write(2).
> >>
> >> Any insight on this topic would be appreciated.
> >>
> >> --
> >> David J. Raymond
> >> [email protected]
> >> http://physics.nmt.edu/~raymond
> >
> > Not in any reasonably modern version of POSIX..
> >
> > https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/limits.h.html
> >
> > {SSIZE_MAX}
> > Maximum value for an object of type ssize_t.
> >
> > $ grep -R "SSIZE_MAX" /usr/include
> > ./amd64/limits.h:#define SSIZE_MAX LONG_MAX /* max value for
> > a ssize_t */
> >
> > /usr/include/sys/limits.h:
> > #ifdef __LP64__
> > ..
> > # define LONG_MAX 0x7fffffffffffffffL
> > ...
> > #else
> > ..
> > # define LONG_MAX 0x7fffffffL
> >
> > -Bryan.
> >
>
>
> --
> David J. Raymond
> [email protected]
> http://physics.nmt.edu/~raymond
>
