20172854ab
Add a pseudofs node flag 'PFS_AUTODRAIN', which automatically emits sbuf contents to the caller when the sbuf buffer fills. This is only permissible if the corresponding PFS node fill function can sleep whenever it appends to the sbuf. linprocfs' /proc/self/maps node happens to meet this requirement. Streaming out the file as it is composed avoids truncating the output and also avoids preallocating a very large buffer. Reviewed by: markj; earlier version: emaste, kib, trasz Differential Revision: https://reviews.freebsd.org/D27047
315 lines
8.8 KiB
C
315 lines
8.8 KiB
C
/*-
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* SPDX-License-Identifier: BSD-3-Clause
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*
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* Copyright (c) 2001 Dag-Erling Coïdan Smørgrav
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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, this list of conditions and the following disclaimer
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* in this position and unchanged.
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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. The name of the author may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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#ifndef _PSEUDOFS_H_INCLUDED
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#define _PSEUDOFS_H_INCLUDED
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#include <sys/jail.h>
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/*
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* Opaque structures
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*/
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struct mntarg;
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struct mount;
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struct nameidata;
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struct proc;
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struct sbuf;
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struct statfs;
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struct thread;
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struct uio;
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struct vfsconf;
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struct vnode;
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/*
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* Limits and constants
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*/
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#define PFS_NAMELEN 128
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#define PFS_FSNAMELEN 16 /* equal to MFSNAMELEN */
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#define PFS_DELEN (offsetof(struct dirent, d_name) + PFS_NAMELEN)
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typedef enum {
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pfstype_none = 0,
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pfstype_root,
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pfstype_dir,
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pfstype_this,
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pfstype_parent,
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pfstype_file,
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pfstype_symlink,
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pfstype_procdir
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} pfs_type_t;
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/*
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* Flags
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*/
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#define PFS_RD 0x0001 /* readable */
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#define PFS_WR 0x0002 /* writeable */
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#define PFS_RDWR (PFS_RD|PFS_WR)
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#define PFS_RAWRD 0x0004 /* raw reader */
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#define PFS_RAWWR 0x0008 /* raw writer */
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#define PFS_RAW (PFS_RAWRD|PFS_RAWWR)
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#define PFS_PROCDEP 0x0010 /* process-dependent */
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#define PFS_NOWAIT 0x0020 /* allow malloc to fail */
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#define PFS_AUTODRAIN 0x0040 /* sbuf_print can sleep to drain */
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/*
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* Data structures
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*/
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struct pfs_info;
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struct pfs_node;
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/*
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* Init / uninit callback
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*/
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#define PFS_INIT_ARGS \
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struct pfs_info *pi, struct vfsconf *vfc
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#define PFS_INIT_ARGNAMES \
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pi, vfc
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#define PFS_INIT_PROTO(name) \
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int name(PFS_INIT_ARGS);
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typedef int (*pfs_init_t)(PFS_INIT_ARGS);
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/*
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* Filler callback
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* Called with proc held but unlocked
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*/
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#define PFS_FILL_ARGS \
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struct thread *td, struct proc *p, struct pfs_node *pn, \
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struct sbuf *sb, struct uio *uio
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#define PFS_FILL_ARGNAMES \
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td, p, pn, sb, uio
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#define PFS_FILL_PROTO(name) \
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int name(PFS_FILL_ARGS);
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typedef int (*pfs_fill_t)(PFS_FILL_ARGS);
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/*
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* Attribute callback
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* Called with proc locked
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*/
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struct vattr;
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#define PFS_ATTR_ARGS \
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struct thread *td, struct proc *p, struct pfs_node *pn, \
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struct vattr *vap
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#define PFS_ATTR_ARGNAMES \
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td, p, pn, vap
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#define PFS_ATTR_PROTO(name) \
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int name(PFS_ATTR_ARGS);
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typedef int (*pfs_attr_t)(PFS_ATTR_ARGS);
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/*
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* Visibility callback
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* Called with proc locked
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*/
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#define PFS_VIS_ARGS \
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struct thread *td, struct proc *p, struct pfs_node *pn
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#define PFS_VIS_ARGNAMES \
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td, p, pn
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#define PFS_VIS_PROTO(name) \
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int name(PFS_VIS_ARGS);
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typedef int (*pfs_vis_t)(PFS_VIS_ARGS);
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/*
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* Ioctl callback
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* Called with proc locked
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*/
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#define PFS_IOCTL_ARGS \
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struct thread *td, struct proc *p, struct pfs_node *pn, \
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unsigned long cmd, void *data
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#define PFS_IOCTL_ARGNAMES \
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td, p, pn, cmd, data
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#define PFS_IOCTL_PROTO(name) \
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int name(PFS_IOCTL_ARGS);
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typedef int (*pfs_ioctl_t)(PFS_IOCTL_ARGS);
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/*
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* Getextattr callback
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* Called with proc locked
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*/
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#define PFS_GETEXTATTR_ARGS \
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struct thread *td, struct proc *p, struct pfs_node *pn, \
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int attrnamespace, const char *name, struct uio *uio, \
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size_t *size, struct ucred *cred
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#define PFS_GETEXTATTR_ARGNAMES \
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td, p, pn, attrnamespace, name, uio, size, cred
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#define PFS_GETEXTATTR_PROTO(name) \
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int name(PFS_GETEXTATTR_ARGS);
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struct ucred;
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typedef int (*pfs_getextattr_t)(PFS_GETEXTATTR_ARGS);
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/*
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* Last-close callback
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* Called with proc locked
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*/
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#define PFS_CLOSE_ARGS \
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struct thread *td, struct proc *p, struct pfs_node *pn
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#define PFS_CLOSE_ARGNAMES \
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td, p, pn
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#define PFS_CLOSE_PROTO(name) \
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int name(PFS_CLOSE_ARGS);
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typedef int (*pfs_close_t)(PFS_CLOSE_ARGS);
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/*
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* Destroy callback
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*/
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#define PFS_DESTROY_ARGS \
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struct pfs_node *pn
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#define PFS_DESTROY_ARGNAMES \
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pn
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#define PFS_DESTROY_PROTO(name) \
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int name(PFS_DESTROY_ARGS);
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typedef int (*pfs_destroy_t)(PFS_DESTROY_ARGS);
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/*
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* pfs_info: describes a pseudofs instance
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*
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* The pi_mutex is only used to avoid using the global subr_unit lock
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* for unrhdr. The rest of struct pfs_info is only modified during
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* vfs_init() and vfs_uninit() of the consumer filesystem.
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*/
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struct pfs_info {
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char pi_name[PFS_FSNAMELEN];
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pfs_init_t pi_init;
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pfs_init_t pi_uninit;
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/* members below this line are initialized at run time */
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struct pfs_node *pi_root;
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struct mtx pi_mutex;
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struct unrhdr *pi_unrhdr;
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};
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/*
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* pfs_node: describes a node (file or directory) within a pseudofs
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*
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* - Fields marked (o) are protected by the node's own mutex.
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* - Fields marked (p) are protected by the node's parent's mutex.
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* - Remaining fields are not protected by any lock and are assumed to be
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* immutable once the node has been created.
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*
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* To prevent deadlocks, if a node's mutex is to be held at the same time
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* as its parent's (e.g. when adding or removing nodes to a directory),
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* the parent's mutex must always be acquired first. Unfortunately, this
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* is not enforcable by WITNESS.
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*/
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struct pfs_node {
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char pn_name[PFS_NAMELEN];
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pfs_type_t pn_type;
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int pn_flags;
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struct mtx pn_mutex;
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void *pn_data; /* (o) */
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pfs_fill_t pn_fill;
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pfs_ioctl_t pn_ioctl;
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pfs_close_t pn_close;
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pfs_attr_t pn_attr;
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pfs_vis_t pn_vis;
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pfs_getextattr_t pn_getextattr;
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pfs_destroy_t pn_destroy;
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struct pfs_info *pn_info;
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u_int32_t pn_fileno; /* (o) */
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struct pfs_node *pn_parent; /* (o) */
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struct pfs_node *pn_nodes; /* (o) */
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struct pfs_node *pn_last_node; /* (o) */
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struct pfs_node *pn_next; /* (p) */
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};
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/*
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* VFS interface
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*/
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int pfs_mount (struct pfs_info *pi, struct mount *mp);
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int pfs_cmount (struct mntarg *ma, void *data, uint64_t flags);
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int pfs_unmount (struct mount *mp, int mntflags);
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int pfs_root (struct mount *mp, int flags,
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struct vnode **vpp);
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int pfs_statfs (struct mount *mp, struct statfs *sbp);
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int pfs_init (struct pfs_info *pi, struct vfsconf *vfc);
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int pfs_uninit (struct pfs_info *pi, struct vfsconf *vfc);
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/*
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* Directory structure construction and manipulation
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*/
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struct pfs_node *pfs_create_dir (struct pfs_node *parent, const char *name,
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pfs_attr_t attr, pfs_vis_t vis,
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pfs_destroy_t destroy, int flags);
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struct pfs_node *pfs_create_file(struct pfs_node *parent, const char *name,
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pfs_fill_t fill, pfs_attr_t attr,
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pfs_vis_t vis, pfs_destroy_t destroy,
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int flags);
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struct pfs_node *pfs_create_link(struct pfs_node *parent, const char *name,
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pfs_fill_t fill, pfs_attr_t attr,
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pfs_vis_t vis, pfs_destroy_t destroy,
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int flags);
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struct pfs_node *pfs_find_node (struct pfs_node *parent, const char *name);
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void pfs_purge (struct pfs_node *pn);
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int pfs_destroy (struct pfs_node *pn);
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/*
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* Now for some initialization magic...
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*/
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#define PSEUDOFS(name, version, flags) \
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\
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static struct pfs_info name##_info = { \
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#name, \
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name##_init, \
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name##_uninit, \
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}; \
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\
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static int \
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_##name##_mount(struct mount *mp) { \
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return (pfs_mount(&name##_info, mp)); \
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} \
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\
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static int \
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_##name##_init(struct vfsconf *vfc) { \
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return (pfs_init(&name##_info, vfc)); \
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} \
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\
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static int \
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_##name##_uninit(struct vfsconf *vfc) { \
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return (pfs_uninit(&name##_info, vfc)); \
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} \
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\
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static struct vfsops name##_vfsops = { \
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.vfs_cmount = pfs_cmount, \
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.vfs_init = _##name##_init, \
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.vfs_mount = _##name##_mount, \
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.vfs_root = pfs_root, \
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.vfs_statfs = pfs_statfs, \
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.vfs_uninit = _##name##_uninit, \
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.vfs_unmount = pfs_unmount, \
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}; \
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VFS_SET(name##_vfsops, name, VFCF_SYNTHETIC | flags); \
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MODULE_VERSION(name, version); \
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MODULE_DEPEND(name, pseudofs, 1, 1, 1);
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#endif
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