to deal with the fact that the public headers may be used with pre-c99
compilers, __restrict is used in place of restrict, and defined
appropriately for any supported compiler. we also avoid the form
[restrict] since older versions of gcc rejected it due to a bug in the
original c99 standard, and instead use the form *restrict.
unlike the memmove commit, this one should be fine to leave in place.
wmemmove is not performance-critical, and even if it were, it's
already copying whole 32-bit words at a time instead of bytes.
this commit introduces a performance regression in many uses of
memmove, which will need to be addressed before the next release. i'm
making it as a temporary measure so that the restrict patch can be
committed without invoking undefined behavior when memmove calls
memcpy with overlapping regions.
since this interface is rarely used, it's probably best to lean
towards keeping code size down anyway. one-character needles will
still be found immediately by the initial wcschr call anyway.
if the buffer is too short, at least return a partial string. this is
helpful if the caller is lazy and does not check for failure. care is
taken to avoid writing anything if the buffer length is zero, and to
always null-terminate when the buffer length is non-zero.
programs that use this tend to horribly botch international text
support, so it's questionable whether we want to support it even in
the long term... for now, it's just a dummy that calls strcmp.
this could actually cause rare crashes in the case where a short
string is located at the end of a page and the following page is not
readable, and in fact this was seen in gcc compiling certain files.
sadly the C language does not specify any such implicit conversion, so
this is not a matter of just fixing warnings (as gcc treats it) but
actual errors. i would like to revisit a number of these changes and
possibly revise the types used to reduce the number of casts required.
this only made the function unnecessarily slow on systems with
unaligned access, but would of course crash on systems that can't do
unaligned accesses (none of which have ports yet).
