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

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

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

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

     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	num-
     ber.  Code	consuming the results of this function should anticipate (and
     properly handle) failure.

     Its arguments are:

     td	      The thread performing the	call; this pointer will	be derefer-
	      enced to find the	process	and its	file descriptor	structure, in
	      order to identify	the root vnode to use.

     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.

     If	the vnode is successfully converted to a pathname, 0 is	returned; oth-
     erwise, an	error number is	returned.


     This manual page was written by Robert Watson <>.

BSD			       November	23, 2008			   BSD


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