Windows代码页与标准C / C ++文件名的交互？

A customer is complaining that our code used to write files with Japanese characters in the filename but no longer works in all cases. We have always just used good old char * strings to represent filenames, so it came as a bit of a shock to me that it ever worked, and we haven't done anything I am aware of that should have made it stop working. I had them send me a file with an embedded filename in it exported from our software, and it looks like the strings use hex characters 82 and 83 as the first character of a double-byte sequence to represent the Japanese characters. Poking around online leads me to believe this is probably SHIFT_JIS and/or Windows codepage 932.A customer is complaining that our code used to