Retrieving the path from a file descriptor or FILE * ?

Question

Is there a way to retrieve path information from a file descriptor or FILE pointer?

I'm aware that this data may not always be relevant/useful for case where the file descriptor is a socket, pipe, etc.

Answer 1

I don't believe there's any portable way, but e.g. on Linux you can call readlink on "/proc/self/fd/fileno" and the kernel will give you a path if it can, or one of various kinds of funny-looking strings if not.

Answer 2

There can be one or many names for a file, so no std way. I am not sure if there can be something OS specific.

Answer 3

If you're lucky enough to be using Mac OS X you can use the following code:

#define _DARWIN_C_SOURCE
#include <sys/fcntl.h>
.
.
.
char pathbuf[PATH_MAX];
if (fcntl(fd, F_GETPATH, pathbuf) >= 0) {
    // pathbuf now contains *a* path to the open file descriptor
}

Note that the path you get back is not necessarily the one used to open the file... If there are hard links, especially, the path you get back will be a valid path to the file.