Provided by: freebsd-manpages_7.2-1_all
vn_fullpath - convert a vnode reference to a full pathname, given a
vn_fullpath(struct thread *td, struct vnode *vp, char **retbuf,
The vn_fullpath() function makes a “best effort” attempt to generate a
string pathname for the passed (locked) 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; must 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 〈rwatson@FreeBSD.org〉.