On Windows, sceKernelPwrite, pwrite, sceKernelPwritev, pwritev and the AIO
write commands wrote at the given offset on a descriptor opened with
O_APPEND. FreeBSD's vn_write sets IO_APPEND for an O_APPEND regular file
whether or not an offset is given, the filesystem then writes at the end of
the file, and the file offset is left unchanged. Write at Windows'
end-of-file offset in that case, and gather a multi-buffer pwritev into one
write as writev already does.
On Windows the C runtime appends by seeking to the end and then writing,
so concurrent appends through different descriptors overwrite each other
and lose data. Write and writev on an O_APPEND descriptor now go through
WriteFile at the end-of-file offset, which Windows appends atomically,
and writev gathers its buffers into one append as FreeBSD writes the
whole vector at the end.
boykopovar