_wfopen equivalent under Mac OS X

Question

I\'m looking to the equivalent of Windows _wfopen() under Mac OS X. Any idea?

I need this in order to port a Windows library that uses wchar* for its File i

Answer 1

You just want to open a file handle using a path that may contain Unicode characters, right? Just pass the path in filesystem representation to fopen.

• If the path came from the stock Mac OS X frameworks (for example, an Open panel whether Carbon or Cocoa), you won't need to do any conversion on it and will be able to use it as-is.

• If you're generating part of the path yourself, you should create a CFStringRef from your path and then get that in filesystem representation to pass to POSIX APIs like open or fopen.

Generally speaking, you won't have to do a lot of that for most applications. For example, many applications may have auxiliary data files stored the user's Application Support directory, but as long as the names of those files are ASCII, and you use standard Mac OS X APIs to locate the user's Application Support directory, you don't need to do a bunch of paranoid conversion of a path constructed with those two components.

Edited to add: I would strongly caution against arbitrarily converting everything to UTF-8 using something like wcstombs because filesystem encoding is not necessarily identical to the generated UTF-8. Mac OS X and Windows both use specific (but different) canonical decomposition rules for the encoding used in filesystem paths.

For example, they need to decide whether "é" will be stored as one or two code units (either LATIN SMALL LETTER E WITH ACUTE or LATIN SMALL LETTER E followed by COMBINING ACUTE ACCENT). These will result in two different — and different-length — byte sequences, and both Mac OS X and Windows work to avoid putting multiple files with the same name (as the user perceives them) in the same directory.

The rules for how to perform this canonical decomposition can get pretty hairy, so rather than try to implement it yourself it's best to leave it to the functions the system frameworks have provided for you to do the heavy lifting.