77d3337c9f
Linux specific things to the native fdescfs file system.
Unlike FreeBSD, the Linux fdescfs is a directory containing a symbolic
links to the actual files, which the process has open.
A readlink(2) call on this file returns a full path in case of regular file
or a string in a special format (type:[inode], anon_inode:<file-type>, etc..).
As well as in a FreeBSD, opening the file in the Linux fdescfs directory is
equivalent to duplicating the corresponding file descriptor.
Here we have mutually exclusive requirements:
- in case of readlink(2) call fdescfs lookup() method should return VLNK
vnode otherwise our kern_readlink() fail with EINVAL error;
- in the other calls fdescfs lookup() method should return non VLNK vnode.
For what new vnode v_flag VV_READLINK was added, which is set if fdescfs has beed
mounted with linrdlnk option an modified kern_readlinkat() to properly handle it.
For now For Linux ABI compatibility mount fdescfs volume with linrdlnk option:
mount -t fdescfs -o linrdlnk null /compat/linux/dev/fd
Reviewed by: kib@
MFC after: 1 week
Relnotes: yes
74 lines
2.5 KiB
C
74 lines
2.5 KiB
C
/*-
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* Copyright (c) 1992, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* This code is derived from software donated to Berkeley by
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* Jan-Simon Pendry.
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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, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, 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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* 3. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER 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
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* SUCH DAMAGE.
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*
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* @(#)fdesc.h 8.5 (Berkeley) 1/21/94
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*
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* $FreeBSD$
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*/
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#ifndef _FS_FDESC_H_
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#define _FS_FDESC_H_
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/* Private mount flags for fdescfs. */
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#define FMNT_UNMOUNTF 0x01
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#define FMNT_LINRDLNKF 0x02
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struct fdescmount {
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struct vnode *f_root; /* Root node */
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int flags;
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};
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#define FD_ROOT 1
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#define FD_DESC 3
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typedef enum {
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Froot,
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Fdesc
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} fdntype;
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struct fdescnode {
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LIST_ENTRY(fdescnode) fd_hash; /* Hash list */
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struct vnode *fd_vnode; /* Back ptr to vnode */
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fdntype fd_type; /* Type of this node */
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unsigned fd_fd; /* Fd to be dup'ed */
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int fd_ix; /* filesystem index */
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};
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extern struct mtx fdesc_hashmtx;
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#define VFSTOFDESC(mp) ((struct fdescmount *)((mp)->mnt_data))
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#define VTOFDESC(vp) ((struct fdescnode *)(vp)->v_data)
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extern vfs_init_t fdesc_init;
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extern vfs_uninit_t fdesc_uninit;
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extern int fdesc_allocvp(fdntype, unsigned, int, struct mount *,
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struct vnode **);
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#endif /* !_FS_FDESC_H_ */
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