C2X has removed K&R definitions from the C function syntax.
Though the standard has not yet been approved, some high-profile
compilers are now issuing warnings when such definitions are
encountered.
Normally these are set to size_t and ssize_t. But if they do not
exist, then they are set to the smallest integer type that can
contain a pointer. size_t is unsigned and ssize_t is signed.
This avoids warnings in OpenBSD that apparently can't be turned
off whenever you link strcpy, strcat, or sprintf. When snprintf
isn't available, the use of the "unsafe" string functions has
always in fact been safe, since the lengths are all checked before
those functions are called.
We do not use strlcpy or strlcat, since they are not (yet) found on
all systems. snprintf on the other hand is part of the C standard
library and is very common.
A common request has been the ability to compile zlib to require no
other libraries. This --solo option provides that ability. The price
is that the gz*, compress*, and uncompress functions are eliminated,
and that the user must provide memory allocation and free routines to
deflate and inflate when initializing.