fd2path – return file name associated with file descriptor

#include <u.h>
#include <libc.h>

int fd2path(int fd, char *buf, int nbuf)

As described in intro(2), the kernel stores a rooted path name with every open file or directory; typically, it is the name used in the original access of the file. Fd2path returns the path name associated with open file descriptor fd. Up to nbuf bytes of the name are stored in buf; if the name is too long, it will be silently truncated at a UTF–8 character boundary. The name is always null–terminated. The return value of fd2path will be zero unless an error occurs.

Changes to the underlying name space do not update the path name stored with the file descriptor. Therefore, the path returned by fd2path may no longer refer to the same file (or indeed any file) after some component directory or file in the path has been removed, renamed or rebound.

As an example, getwd(2) is implemented by opening . and executing fd2path on the resulting file descriptor.


bind(1), ns(1), bind(2), intro(2), getwd(2), proc(3)

Sets errstr.
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