1.\" 2.\" Copyright (c) 2003 Robert N. M. Watson. 3.\" All rights reserved. 4.\" 5.\" Redistribution and use in source and binary forms, with or without 6.\" modification, are permitted provided that the following conditions 7.\" are met: 8.\" 1. Redistributions of source code must retain the above copyright 9.\" notice(s), this list of conditions and the following disclaimer as 10.\" the first lines of this file unmodified other than the possible 11.\" addition of one or more copyright notices. 12.\" 2. Redistributions in binary form must reproduce the above copyright 13.\" notice(s), this list of conditions and the following disclaimer in the 14.\" documentation and/or other materials provided with the distribution. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY 17.\" EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 18.\" WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 19.\" DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE LIABLE FOR ANY 20.\" DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES 21.\" (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR 22.\" SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER 23.\" CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH 26.\" DAMAGE. 27.\" 28.\" $FreeBSD$ 29.\" 30.Dd June 15, 2021 31.Dt VN_FULLPATH 9 32.Os 33.Sh NAME 34.Nm vn_fullpath 35.Nd "convert a vnode reference to a full pathname, given a process context" 36.Sh SYNOPSIS 37.In sys/param.h 38.In sys/vnode.h 39.Ft int 40.Fo vn_fullpath 41.Fa "struct vnode *vp" "char **retbuf" "char **freebuf" 42.Fc 43.Sh DESCRIPTION 44The 45.Fn vn_fullpath 46function makes a 47.Dq "best effort" 48attempt to generate a string pathname for 49the passed vnode; the resulting path, if any, will be relative to 50the root directory of the process associated with the passed thread pointer. 51The 52.Fn vn_fullpath 53function 54is implemented by inspecting the VFS name cache, and attempting to 55reconstruct a path from the process root to the object. 56.Pp 57This process is necessarily unreliable for several reasons: intermediate 58entries in the path may not be found in the cache; files may have more 59than one name (hard links), not all file systems use the name cache 60(specifically, most synthetic file systems do not); a single name may 61be used for more than one file (in the context of file systems covering 62other file systems); a file may have no name (if deleted but still 63open or referenced). 64However, the resulting string may still be more useable to a user than 65a vnode pointer value, or a device number and inode number. 66Code consuming the results of this function should anticipate (and 67properly handle) failure. 68.Pp 69Its arguments are: 70.Bl -tag -width ".Fa freebuf" 71.It Fa vp 72The vnode to search for. 73No need to be locked by the caller. 74.It Fa retbuf 75Pointer to a 76.Vt "char *" 77that 78.Fn vn_fullpath 79may (on success) point at a newly 80allocated buffer containing the resulting pathname. 81.It Fa freebuf 82Pointer to a 83.Vt "char *" 84that 85.Fn vn_fullpath 86may (on success) point at a buffer 87to be freed, when the caller is done with 88.Fa retbuf . 89.El 90.Pp 91Typical consumers will declare two character pointers: 92.Va fullpath 93and 94.Va freepath ; 95they will set 96.Va freepath 97to 98.Dv NULL , 99and 100.Va fullpath 101to a name to use 102in the event that the call to 103.Fn vn_fullpath 104fails. 105After done with the value of 106.Va fullpath , 107the caller will check if 108.Va freepath 109is 110.Pf non- Dv NULL , 111and if so, invoke 112.Xr free 9 113with a pool type of 114.Dv M_TEMP . 115.Sh RETURN VALUES 116If the vnode is successfully converted to a pathname, 0 is returned; 117otherwise, an error number is returned. 118.Sh SEE ALSO 119.Xr free 9 120.Sh AUTHORS 121This manual page was written by 122.An Robert Watson Aq Mt rwatson@FreeBSD.org . 123