124 lines
3.9 KiB
C
124 lines
3.9 KiB
C
/*
|
|
* Copyright (c) 2014
|
|
* The President and Fellows of Harvard College.
|
|
*
|
|
* Redistribution and use in source and binary forms, with or without
|
|
* modification, are permitted provided that the following conditions
|
|
* are met:
|
|
* 1. Redistributions of source code must retain the above copyright
|
|
* notice, this list of conditions and the following disclaimer.
|
|
* 2. Redistributions in binary form must reproduce the above copyright
|
|
* notice, this list of conditions and the following disclaimer in the
|
|
* documentation and/or other materials provided with the distribution.
|
|
* 3. Neither the name of the University nor the names of its contributors
|
|
* may be used to endorse or promote products derived from this software
|
|
* without specific prior written permission.
|
|
*
|
|
* THIS SOFTWARE IS PROVIDED BY THE UNIVERSITY AND CONTRIBUTORS ``AS IS'' AND
|
|
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
* ARE DISCLAIMED. IN NO EVENT SHALL THE UNIVERSITY OR CONTRIBUTORS BE LIABLE
|
|
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
|
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
|
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
|
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
|
* SUCH DAMAGE.
|
|
*/
|
|
|
|
#ifndef SEMFS_H
|
|
#define SEMFS_H
|
|
|
|
#include <array.h>
|
|
#include <fs.h>
|
|
#include <vnode.h>
|
|
|
|
#ifndef SEMFS_INLINE
|
|
#define SEMFS_INLINE INLINE
|
|
#endif
|
|
|
|
/*
|
|
* Constants
|
|
*/
|
|
|
|
#define SEMFS_ROOTDIR 0xffffffffU /* semnum for root dir */
|
|
|
|
/*
|
|
* A user-facing semaphore.
|
|
*
|
|
* We don't use the kernel-level semaphore to implement it (although
|
|
* that would be tidy) because we'd have to violate its abstraction.
|
|
* XXX: or would we? review once all this is done.
|
|
*/
|
|
struct semfs_sem {
|
|
struct lock *sems_lock; /* Lock to protect count */
|
|
struct cv *sems_cv; /* CV to wait */
|
|
unsigned sems_count; /* Semaphore count */
|
|
bool sems_hasvnode; /* The vnode exists */
|
|
bool sems_linked; /* In the directory */
|
|
};
|
|
DECLARRAY(semfs_sem, SEMFS_INLINE);
|
|
|
|
/*
|
|
* Directory entry; name and reference to a semaphore.
|
|
*/
|
|
struct semfs_direntry {
|
|
char *semd_name; /* Name */
|
|
unsigned semd_semnum; /* Which semaphore */
|
|
};
|
|
DECLARRAY(semfs_direntry, SEMFS_INLINE);
|
|
|
|
/*
|
|
* Vnode. These are separate from the semaphore structures so they can
|
|
* come and go at the whim of VOP_RECLAIM. (It might seem tidier to
|
|
* ignore VOP_RECLAIM and destroy vnodes only when the underlying
|
|
* objects are removed; but it ends up being more complicated in
|
|
* practice. XXX: review after finishing)
|
|
*/
|
|
struct semfs_vnode {
|
|
struct vnode semv_absvn; /* Abstract vnode */
|
|
struct semfs *semv_semfs; /* Back-pointer to fs */
|
|
unsigned semv_semnum; /* Which semaphore */
|
|
};
|
|
|
|
/*
|
|
* The structure for the semaphore file system. Ordinarily there
|
|
* is only one of these.
|
|
*/
|
|
struct semfs {
|
|
struct fs semfs_absfs; /* Abstract fs object */
|
|
|
|
struct lock *semfs_tablelock; /* Lock for following */
|
|
struct vnodearray *semfs_vnodes; /* Currently extant vnodes */
|
|
struct semfs_semarray *semfs_sems; /* Semaphores */
|
|
|
|
struct lock *semfs_dirlock; /* Lock for following */
|
|
struct semfs_direntryarray *semfs_dents; /* The root directory */
|
|
};
|
|
|
|
/*
|
|
* Arrays
|
|
*/
|
|
|
|
DEFARRAY(semfs_sem, SEMFS_INLINE);
|
|
DEFARRAY(semfs_direntry, SEMFS_INLINE);
|
|
|
|
|
|
/*
|
|
* Functions.
|
|
*/
|
|
|
|
/* in semfs_obj.c */
|
|
struct semfs_sem *semfs_sem_create(const char *name);
|
|
int semfs_sem_insert(struct semfs *, struct semfs_sem *, unsigned *);
|
|
void semfs_sem_destroy(struct semfs_sem *);
|
|
struct semfs_direntry *semfs_direntry_create(const char *name, unsigned semno);
|
|
void semfs_direntry_destroy(struct semfs_direntry *);
|
|
|
|
/* in semfs_vnops.c */
|
|
int semfs_getvnode(struct semfs *, unsigned, struct vnode **ret);
|
|
|
|
|
|
#endif /* SEMFS_H */
|