freebsd/sys/sys/filedesc.h

/*
 * Copyright (c) 1990, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * 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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. 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 REGENTS 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 REGENTS 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.
 *
 *	@(#)filedesc.h	8.1 (Berkeley) 6/2/93
 * $FreeBSD$
 */

#ifndef _SYS_FILEDESC_H_
#define	_SYS_FILEDESC_H_

#include <sys/_lock.h>
#include <sys/_mutex.h>
#include <sys/queue.h>

/*
 * This structure is used for the management of descriptors.  It may be
 * shared by multiple processes.
 *
 * A process is initially started out with NDFILE descriptors stored within
 * this structure, selected to be enough for typical applications based on
 * the historical limit of 20 open files (and the usage of descriptors by
 * shells).  If these descriptors are exhausted, a larger descriptor table
 * may be allocated, up to a process' resource limit; the internal arrays
 * are then unused.  The initial expansion is set to NDEXTENT; each time
 * it runs out, it is doubled until the resource limit is reached. NDEXTENT
 * should be selected to be the biggest multiple of OFILESIZE (see below)
 * that will fit in a power-of-two sized piece of memory.
 */
#define NDFILE		20
#define NDEXTENT	50		/* 250 bytes in 256-byte alloc. */

struct filedesc {
	struct	file **fd_ofiles;	/* file structures for open files */
	char	*fd_ofileflags;		/* per-process open file flags */
	struct	vnode *fd_cdir;		/* current directory */
	struct	vnode *fd_rdir;		/* root directory */
	struct	vnode *fd_jdir;		/* jail root directory */
	int	fd_nfiles;		/* number of open files allocated */
	int	fd_lastfile;		/* high-water mark of fd_ofiles */
	int	fd_freefile;		/* approx. next free file */
	u_short	fd_cmask;		/* mask for file creation */
	u_short	fd_refcnt;		/* reference count */

	int	fd_knlistsize;		/* size of knlist */
	struct	klist *fd_knlist;	/* list of attached knotes */
	u_long	fd_knhashmask;		/* size of knhash */
	struct	klist *fd_knhash;	/* hash table for attached knotes */
	struct mtx	fd_mtx;		/* mtx to protect the members of struct filedesc */
};

/*
 * Basic allocation of descriptors:
 * one of the above, plus arrays for NDFILE descriptors.
 */
struct filedesc0 {
	struct	filedesc fd_fd;
	/*
	 * These arrays are used when the number of open files is
	 * <= NDFILE, and are then pointed to by the pointers above.
	 */
	struct	file *fd_dfiles[NDFILE];
	char	fd_dfileflags[NDFILE];
};

/*
 * Per-process open flags.
 */
#define	UF_EXCLOSE 	0x01		/* auto-close on exec */
#if 0
#define	UF_MAPPED 	0x02		/* mapped from device */
#endif

/*
 * Storage required per open file descriptor.
 */
#define OFILESIZE (sizeof(struct file *) + sizeof(char))

/*
 * This structure holds the information needed to send a SIGIO or
 * a SIGURG signal to a process or process group when new data arrives
 * on a device or socket.  The structure is placed on an SLIST belonging
 * to the proc or pgrp so that the entire list may be revoked when the
 * process exits or the process group disappears.
 *
 * (c)	const
 * (pg)	locked by either the process or process group lock
 */
struct sigio {
	union {
		struct	proc *siu_proc; /* (c)	process to receive SIGIO/SIGURG */
		struct	pgrp *siu_pgrp; /* (c)	process group to receive ... */
	} sio_u;
	SLIST_ENTRY(sigio) sio_pgsigio;	/* (pg)	sigio's for process or group */
	struct	sigio **sio_myref;	/* (c)	location of the pointer that holds
					 * 	the reference to this structure */
	struct	ucred *sio_ucred;	/* (c)	current credentials */
	pid_t	sio_pgid;		/* (c)	pgid for signals */
};
#define	sio_proc	sio_u.siu_proc
#define	sio_pgrp	sio_u.siu_pgrp

SLIST_HEAD(sigiolst, sigio);

#ifdef _KERNEL

#define FILEDESC_LOCK_DESC	"filedesc structure"

/* Lock a file descriptor table. */
#define FILEDESC_LOCK(fd)	mtx_lock(&(fd)->fd_mtx)
#define FILEDESC_UNLOCK(fd)	mtx_unlock(&(fd)->fd_mtx)
#define	FILEDESC_LOCKED(fd)	mtx_owned(&(fd)->fd_mtx)
#define	FILEDESC_LOCK_ASSERT(fd, type)	mtx_assert(&(fd)->fd_mtx, (type))

int	closef(struct file *fp, struct thread *p);
int	dupfdopen(struct thread *td, struct filedesc *fdp, int indx, int dfd,
	    int mode, int error);
int	falloc(struct thread *p, struct file **resultfp, int *resultfd);
int	fdalloc(struct thread *p, int want, int *result);
int	fdavail(struct thread *td, int n);
void	fdcloseexec(struct thread *td);
int	fdcheckstd(struct thread *td);
struct	filedesc *fdcopy(struct thread *td);
void	fdfree(struct thread *td);
struct	filedesc *fdinit(struct thread *td);
struct	filedesc *fdshare(struct proc *p);
void	ffree(struct file *fp);
static __inline struct file *	fget_locked(struct filedesc *fdp, int fd);
pid_t	fgetown(struct sigio *sigio);
int	fsetown(pid_t pgid, struct sigio **sigiop);
void	funsetown(struct sigio **sigiop);
void	funsetownlst(struct sigiolst *sigiolst);
int	getvnode(struct filedesc *fdp, int fd, struct file **fpp);
void	setugidsafety(struct thread *td);

static __inline struct file *
fget_locked(struct filedesc *fdp, int fd)
{

	/* u_int cast checks for negative descriptors. */
	return ((u_int)fd >= (u_int)fdp->fd_nfiles ? NULL : fdp->fd_ofiles[fd]);
}

#endif /* _KERNEL */

#endif /* !_SYS_FILEDESC_H_ */