"Schwarz, Konrad" <[EMAIL PROTECTED]> writes: > What is the justification for making the return value of read() have type > ssize_t?
Again, I wasn't there. But when ssize_t was invented, C89 (and therefore ptrdiff_t) was not required by POSIX, so I expect the original motivation was that POSIX wanted a type and could not assume ptrdiff_t (and couldn't define ptrdiff_t either, due to potential clashes). Nowadays it's conventional wisdom that ssize_t must be the same width as size_t, and I expect that code relies on this even if POSIX doesn't require it. It's not conventional wisdom that ptrdiff_t must be the same width as size_t, because implementations may want ptrdiff_t to be reliable, and in general ptrdiff_t is not reliable unless it's wider than size_t. So there's still a gap between the two types in principle, not that I know of any modern implementation where they actually differ.
