VN_FULLPATH(9)         FreeBSD Kernel Developer's Manual        VN_FULLPATH(9)

NAME
     vn_fullpath - convert a vnode reference to a full pathname, given a
     process context

SYNOPSIS
     #include <sys/param.h>
     #include <sys/vnode.h>

     int
     vn_fullpath(struct vnode *vp, char **retbuf, char **freebuf);

DESCRIPTION
     The vn_fullpath() function makes a "best effort" attempt to generate a
     string pathname for the passed vnode; the resulting path, if any, will be
     relative to the root directory of the process associated with the passed
     thread pointer.  The vn_fullpath() function is implemented by inspecting
     the VFS name cache, and attempting to reconstruct a path from the process
     root to the object.

     This process is necessarily unreliable for several reasons: intermediate
     entries in the path may not be found in the cache; files may have more
     than one name (hard links), not all file systems use the name cache
     (specifically, most synthetic file systems do not); a single name may be
     used for more than one file (in the context of file systems covering
     other file systems); a file may have no name (if deleted but still open
     or referenced).  However, the resulting string may still be more useable
     to a user than a vnode pointer value, or a device number and inode
     number.  Code consuming the results of this function should anticipate
     (and properly handle) failure.

     Its arguments are:

     vp           The vnode to search for.  No need to be locked by the
                  caller.

     retbuf       Pointer to a char * that vn_fullpath() may (on success)
                  point at a newly allocated buffer containing the resulting
                  pathname.

     freebuf      Pointer to a char * that vn_fullpath() may (on success)
                  point at a buffer to be freed, when the caller is done with
                  retbuf.

     Typical consumers will declare two character pointers: fullpath and
     freepath; they will set freepath to NULL, and fullpath to a name to use
     in the event that the call to vn_fullpath() fails.  After done with the
     value of fullpath, the caller will check if freepath is non-NULL, and if
     so, invoke free(9) with a pool type of M_TEMP.

RETURN VALUES
     If the vnode is successfully converted to a pathname, 0 is returned;
     otherwise, an error number is returned.

SEE ALSO
     free(9)

AUTHORS
     This manual page was written by Robert Watson <rwatson@FreeBSD.org>.

FreeBSD 13.1-RELEASE-p6          June 15, 2021         FreeBSD 13.1-RELEASE-p6