127 lines
4.0 KiB
Groff
127 lines
4.0 KiB
Groff
.\"
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.\" Copyright (c) 2003 Robert N. M. Watson.
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice(s), this list of conditions and the following disclaimer as
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.\" the first lines of this file unmodified other than the possible
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.\" addition of one or more copyright notices.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice(s), this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
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.\" EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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.\" WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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.\" DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE LIABLE FOR ANY
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.\" DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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.\" (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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.\" SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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.\" CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
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.\" DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd November 23, 2008
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.Dt VN_FULLPATH 9
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.Os
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.Sh NAME
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.Nm vn_fullpath
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.Nd "convert a vnode reference to a full pathname, given a process context"
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.Sh SYNOPSIS
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.In sys/param.h
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.In sys/vnode.h
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.Ft int
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.Fo vn_fullpath
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.Fa "struct thread *td" "struct vnode *vp" "char **retbuf" "char **freebuf"
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.Fc
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.Sh DESCRIPTION
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The
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.Fn vn_fullpath
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function makes a
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.Dq "best effort"
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attempt to generate a string pathname for
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the passed vnode; the resulting path, if any, will be relative to
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the root directory of the process associated with the passed thread pointer.
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The
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.Fn vn_fullpath
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function
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is implemented by inspecting the VFS name cache, and attempting to
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reconstruct a path from the process root to the object.
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.Pp
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This process is necessarily unreliable for several reasons: intermediate
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entries in the path may not be found in the cache; files may have more
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than one name (hard links), not all file systems use the name cache
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(specifically, most synthetic file systems do not); a single name may
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be used for more than one file (in the context of file systems covering
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other file systems); a file may have no name (if deleted but still
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open or referenced).
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However, the resulting string may still be more useable to a user than
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a vnode pointer value, or a device number and inode number.
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Code consuming the results of this function should anticipate (and
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properly handle) failure.
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.Pp
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Its arguments are:
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.Bl -tag -width ".Fa freebuf"
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.It Fa td
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The thread performing the call; this pointer will be dereferenced to find
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the process and its file descriptor structure, in order to identify the
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root vnode to use.
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.It Fa vp
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The vnode to search for.
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No need to be locked by the caller.
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.It Fa retbuf
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Pointer to a
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.Vt "char *"
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that
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.Fn vn_fullpath
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may (on success) point at a newly
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allocated buffer containing the resulting pathname.
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.It Fa freebuf
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Pointer to a
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.Vt "char *"
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that
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.Fn vn_fullpath
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may (on success) point at a buffer
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to be freed, when the caller is done with
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.Fa retbuf .
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.El
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.Pp
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Typical consumers will declare two character pointers:
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.Va fullpath
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and
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.Va freepath ;
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they will set
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.Va freepath
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to
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.Dv NULL ,
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and
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.Va fullpath
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to a name to use
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in the event that the call to
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.Fn vn_fullpath
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fails.
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After done with the value of
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.Va fullpath ,
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the caller will check if
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.Va freepath
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is
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.Pf non- Dv NULL ,
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and if so, invoke
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.Xr free 9
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with a pool type of
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.Dv M_TEMP .
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.Sh RETURN VALUES
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If the vnode is successfully converted to a pathname, 0 is returned;
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otherwise, an error number is returned.
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.Sh SEE ALSO
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.Xr free 9
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.Sh AUTHORS
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This manual page was written by
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.An Robert Watson Aq Mt rwatson@FreeBSD.org .
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