Is there any cross platform file IO / path util library for C?

Question

Is there some C library that implements platform independent version of path operations?

Some examples that come to mind:

• Getting the absolute path from a relative one (without requiring the file to exist)
• Ensuring a directory exists.
• Creating a file if non-existent, and any directory in the given path that is missing.
• Concatenating paths.
• Getting directory part of path.
• Getting filename part of path.
• Lots more....

There are of course platform specific versions of these, but they hardly ever do exactly the same thing leading to chaos trying to match behaviour across platforms.

And I mean C, not C++, so boost doesn't count.

Also if there is none, are there any good sources/examples of differences between platforms, and other useful information that can be used to write such a library?

Answer 1

I know this is a rather old question, but I have been looking for something like this and couldn't find anything. So I wrote one, cwalk (reference) - for anyone who still finds it useful! :-)

Answer 2

I found the Apache Portable Runtime Project (APR) which does a lot more than just file I/O and path operations. And is not tied to any project like Gnome.

Another project that has portable functions for this with a nice API is CZMQ with the zfile and zsys classes, although the library itself focuses on other things.

Answer 3

The ever-nice glib family (part of GTK+) has some, at least.

• The misc utility functions API has functions like g_path_is_absolute() and others
• The I/O virtualization wrapper API GIO has g_file_make_directory_with_parents().

Note that some of the functions you're describing, such as "getting absolute path from relative one" assumes the existence of a current directory, which is how that resolution is typically done. It's not a very "pure" function, since it relies on external state. In Windows, with its "split file system", there is even one current directory per volume (e.g. one for C:\, one for A:\ if you have it, and so on) per process.