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 November 23, 2008 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 thread *td" "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 td 72The thread performing the call; this pointer will be dereferenced to find 73the process and its file descriptor structure, in order to identify the 74root vnode to use. 75.It Fa vp 76The vnode to search for. 77No need to be locked by the caller. 78.It Fa retbuf 79Pointer to a 80.Vt "char *" 81that 82.Fn vn_fullpath 83may (on success) point at a newly 84allocated buffer containing the resulting pathname. 85.It Fa freebuf 86Pointer to a 87.Vt "char *" 88that 89.Fn vn_fullpath 90may (on success) point at a buffer 91to be freed, when the caller is done with 92.Fa retbuf . 93.El 94.Pp 95Typical consumers will declare two character pointers: 96.Va fullpath 97and 98.Va freepath ; 99they will set 100.Va freepath 101to 102.Dv NULL , 103and 104.Va fullpath 105to a name to use 106in the event that the call to 107.Fn vn_fullpath 108fails. 109After done with the value of 110.Va fullpath , 111the caller will check if 112.Va freepath 113is 114.Pf non- Dv NULL , 115and if so, invoke 116.Xr free 9 117with a pool type of 118.Dv M_TEMP . 119.Sh RETURN VALUES 120If the vnode is successfully converted to a pathname, 0 is returned; 121otherwise, an error number is returned. 122.Sh SEE ALSO 123.Xr free 9 124.Sh AUTHORS 125This manual page was written by 126.An Robert Watson Aq Mt rwatson@FreeBSD.org . 127