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     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
     number.  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
              dereferenced 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;
     otherwise, an error number is returned.




     This manual page was written by Robert Watson ⟨⟩.