.\"- .\" SPDX-License-Identifier: BSD-2-Clause .\" .\" Copyright (c) 2003 Robert N. M. Watson. .\" All rights reserved. .\" Copyright (c) 2025 The FreeBSD Foundation .\" .\" Portions of this documentation were written by Olivier Certner .\" at Kumacom SARL under sponsorship from the FreeBSD .\" Foundation. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice(s), this list of conditions and the following disclaimer as .\" the first lines of this file unmodified other than the possible .\" addition of one or more copyright notices. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice(s), this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" .\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY .\" EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED .\" WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE .\" DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE LIABLE FOR ANY .\" DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES .\" (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR .\" SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER .\" CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH .\" DAMAGE. .\" .Dd September 29, 2025 .Dt VN_FULLPATH 9 .Os .Sh NAME .Nm vn_fullpath .Nd "convert a vnode reference to a full pathname, given a process context" .Sh SYNOPSIS .In sys/param.h .In sys/vnode.h .Ft int .Fn vn_fullpath "struct vnode *vp" "char **retbuf" "char **freebuf" .Ft int .Fn vn_fullpath_jail "struct vnode *vp" "char **retbuf" "char **freebuf" .Ft int .Fn vn_fullpath_global "struct vnode *vp" "char **retbuf" "char **freebuf" .Ft int .Fo vn_fullpath_hardlink .Fa "struct vnode *vp" "struct vnode *dvp" .Fa "const char *hrdl_name" "size_t hrdl_name_length" .Fa "char **retbuf" "char **freebuf" "size_t *buflen" .Fc .Sh DESCRIPTION The .Fn vn_fullpath , .Fn vn_fullpath_jail , .Fn vn_fullpath_global and .Fn vn_fullpath_hardlink functions make a .Dq best effort attempt at generating a string pathname for the passed vnode. They differ in which directory the returned path is relative to, except for .Fn vn_fullpath_hardlink which behaves like .Fn vn_fullpath in this respect and is described at the end. .Pp The .Fn vn_fullpath function returns a path relative to the root directory of the process associated with the passed thread pointer. That root directory is either the system's or the thread's process' containing jail's root directory, or some descendant directory of such established by some .Xr chroot 2 call. The .Fn vn_fullpath_jail function returns a path relative to the passed thread's process' current jail's root, ignoring intervening .Xr chroot 2 calls possibly made inside that jail. The .Fn vn_fullpath_global function returns the full path from the system root, ignoring all jail roots and .Xr chroot 2 calls. .Pp Paths that the kernel intends to communicate to the passed user thread should exclusively be obtained via .Fn vn_fullpath . Paths obtained via .Fn vn_fullpath_jail or .Fn vn_fullpath_global are only useful for specific kernel checks or auditing purposes. .Pp All these functions are 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 usable 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. .Pp These functions take the following arguments: .Bl -tag -width ".Fa freebuf" .It Fa vp The vnode to search for. No need to be locked by the caller. .It Fa retbuf Pointer to a .Vt "char *" that may be set (on success) to point at a newly allocated buffer containing the resulting pathname. .It Fa freebuf Pointer to a .Vt "char *" that may be set (on success) to point at a buffer to be freed, when the caller is done with .Fa retbuf . .El .Pp Typical consumers will declare two character pointers: .Va fullpath and .Va freepath ; they will set .Va freepath to .Dv NULL , and .Va fullpath to a name to use in the event that the call to .Fn vn_fullpath fails. After done with the value of .Va fullpath , the caller will check if .Va freepath is .Pf non- Dv NULL , and if so, invoke .Xr free 9 with a pool type of .Dv M_TEMP . .Pp The .Fn vn_fullpath_hardlink function is a convenience wrapper which automatically appends the hardlink name passed via arguments .Fa hrdl_name and .Fa hrdl_name_length to the result of calling .Fn vn_fullpath on the vnode's parent directory. It requires the results of a prior call to .Xr namei 9 with flag .Dv WANTPARENT to be passed in the .Fa vp and .Fa dvp arguments. Argument .Fa buflen must point to a valid storage containing the size of the desired buffer, which will be reduced to .Dv MAXPATHLEN if in excess of it. .Sh RETURN VALUES If the vnode is successfully converted to a pathname, 0 is returned; otherwise, an error number is returned. .Sh SEE ALSO .Xr free 9 .Sh AUTHORS .An -nosplit This manual page was initially written by .An Robert Watson Aq Mt rwatson@FreeBSD.org to describe the .Fn vn_fullpath function. The descriptions of the other related functions were added by .An Olivier Certner Aq Mt olce@FreeBSD.org .