This is a bit "hard", because getenv() returns a static string, and we
can't just return an allocated string. We also want getenv() to be
thread-safe if possible. (If the mpv core is going to be more threaded,
we sure do want the lower layers to be thread-safe as well.)
I have no idea when or how this broke, but _wstati64() is the function
we want anyway (64 bit filesize). Possibly this was a mingw-w64 bug.
It's unknown why "wstat()" just doesn't work in this case, as it's not
defined by MSDN and could be defined by mingw as it needs.
Use the *W variants instead of the implicit *A functions. (One could
define the UNICODE macro to switch the functions without suffix from
A to W, but I'm too lazy to figure out how portable that is, etc.)
Also make sure io.h defines a unicode aware printf().
Windows uses a legacy codepage for char* / runtime functions accepting
char *. Using UTF-8 as the codepage with setlocale() is explicitly
forbidden.
Work this around by overriding the MSVCRT functions with wrapper
macros, that assume UTF-8 and use "proper" API calls like _wopen etc.
to deal with unicode filenames. All code that uses standard functions
that take or return filenames must now include osdep/io.h. stat()
can't be overridden, because MinGW-w64 itself defines "stat" as a
macro. Change code to use use mp_stat() instead.
This is not perfectly clean, but still somewhat sane, and much better
than littering the rest of the mplayer code with MinGW specific hacks.
It's also a bit fragile, but that's actually little different from the
previous situation. Also, MinGW is unlikely to ever include a nice way
of dealing with this.