xref: /f-stack/freebsd/sys/filedesc.h (revision a9643ea8)

/*-
 * 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.
 * 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/caprights.h>
#include <sys/queue.h>
#include <sys/event.h>
#include <sys/lock.h>
#include <sys/priority.h>
#include <sys/seq.h>
#include <sys/sx.h>

#include <machine/_limits.h>

struct filecaps {
	cap_rights_t	 fc_rights;	/* per-descriptor capability rights */
	u_long		*fc_ioctls;	/* per-descriptor allowed ioctls */
	int16_t		 fc_nioctls;	/* fc_ioctls array size */
	uint32_t	 fc_fcntls;	/* per-descriptor allowed fcntls */
};

struct filedescent {
	struct file	*fde_file;	/* file structure for open file */
	struct filecaps	 fde_caps;	/* per-descriptor rights */
	uint8_t		 fde_flags;	/* per-process open file flags */
	seq_t		 fde_seq;	/* keep file and caps in sync */
};
#define	fde_rights	fde_caps.fc_rights
#define	fde_fcntls	fde_caps.fc_fcntls
#define	fde_ioctls	fde_caps.fc_ioctls
#define	fde_nioctls	fde_caps.fc_nioctls
#define	fde_change_size	(offsetof(struct filedescent, fde_seq))

struct fdescenttbl {
	int	fdt_nfiles;		/* number of open files allocated */
	struct	filedescent fdt_ofiles[0];	/* open files */
};
#define	fd_seq(fdt, fd)	(&(fdt)->fdt_ofiles[(fd)].fde_seq)

/*
 * This structure is used for the management of descriptors.  It may be
 * shared by multiple processes.
 */
#define NDSLOTTYPE	u_long

struct filedesc {
	struct	fdescenttbl *fd_files;	/* open files table */
	struct	vnode *fd_cdir;		/* current directory */
	struct	vnode *fd_rdir;		/* root directory */
	struct	vnode *fd_jdir;		/* jail root directory */
	NDSLOTTYPE *fd_map;		/* bitmap of free fds */
	int	fd_lastfile;		/* high-water mark of fd_ofiles */
	int	fd_freefile;		/* approx. next free file */
	u_short	fd_cmask;		/* mask for file creation */
	int	fd_refcnt;		/* thread reference count */
	int	fd_holdcnt;		/* hold count on structure + mutex */
	struct	sx fd_sx;		/* protects members of this struct */
	struct	kqlist fd_kqlist;	/* list of kqueues on this filedesc */
	int	fd_holdleaderscount;	/* block fdfree() for shared close() */
	int	fd_holdleaderswakeup;	/* fdfree() needs wakeup */
};

/*
 * Structure to keep track of (process leader, struct fildedesc) tuples.
 * Each process has a pointer to such a structure when detailed tracking
 * is needed, e.g., when rfork(RFPROC | RFMEM) causes a file descriptor
 * table to be shared by processes having different "p_leader" pointers
 * and thus distinct POSIX style locks.
 *
 * fdl_refcount and fdl_holdcount are protected by struct filedesc mtx.
 */
struct filedesc_to_leader {
	int		fdl_refcount;	/* references from struct proc */
	int		fdl_holdcount;	/* temporary hold during closef */
	int		fdl_wakeup;	/* fdfree() waits on closef() */
	struct proc	*fdl_leader;	/* owner of POSIX locks */
	/* Circular list: */
	struct filedesc_to_leader *fdl_prev;
	struct filedesc_to_leader *fdl_next;
};
#define	fd_nfiles	fd_files->fdt_nfiles
#define	fd_ofiles	fd_files->fdt_ofiles

/*
 * Per-process open flags.
 */
#define	UF_EXCLOSE	0x01		/* auto-close on exec */

#ifdef _KERNEL

/* Lock a file descriptor table. */
#define	FILEDESC_LOCK_INIT(fdp)	sx_init(&(fdp)->fd_sx, "filedesc structure")
#define	FILEDESC_LOCK_DESTROY(fdp)	sx_destroy(&(fdp)->fd_sx)
#define	FILEDESC_LOCK(fdp)	(&(fdp)->fd_sx)
#define	FILEDESC_XLOCK(fdp)	sx_xlock(&(fdp)->fd_sx)
#define	FILEDESC_XUNLOCK(fdp)	sx_xunlock(&(fdp)->fd_sx)
#define	FILEDESC_SLOCK(fdp)	sx_slock(&(fdp)->fd_sx)
#define	FILEDESC_SUNLOCK(fdp)	sx_sunlock(&(fdp)->fd_sx)

#define	FILEDESC_LOCK_ASSERT(fdp)	sx_assert(&(fdp)->fd_sx, SX_LOCKED | \
					    SX_NOTRECURSED)
#define	FILEDESC_XLOCK_ASSERT(fdp)	sx_assert(&(fdp)->fd_sx, SX_XLOCKED | \
					    SX_NOTRECURSED)
#define	FILEDESC_UNLOCK_ASSERT(fdp)	sx_assert(&(fdp)->fd_sx, SX_UNLOCKED)

/* Operation types for kern_dup(). */
enum {
	FDDUP_NORMAL,		/* dup() behavior. */
	FDDUP_FCNTL,		/* fcntl()-style errors. */
	FDDUP_FIXED,		/* Force fixed allocation. */
	FDDUP_MUSTREPLACE,	/* Target must exist. */
	FDDUP_LASTMODE,
};

/* Flags for kern_dup(). */
#define	FDDUP_FLAG_CLOEXEC	0x1	/* Atomically set UF_EXCLOSE. */

/* For backward compatibility. */
#define	falloc(td, resultfp, resultfd, flags) \
	falloc_caps(td, resultfp, resultfd, flags, NULL)

struct thread;

void	filecaps_init(struct filecaps *fcaps);
int	filecaps_copy(const struct filecaps *src, struct filecaps *dst,
	    bool locked);
void	filecaps_move(struct filecaps *src, struct filecaps *dst);
void	filecaps_free(struct filecaps *fcaps);

int	closef(struct file *fp, struct thread *td);
int	dupfdopen(struct thread *td, struct filedesc *fdp, int dfd, int mode,
	    int openerror, int *indxp);
int	falloc_caps(struct thread *td, struct file **resultfp, int *resultfd,
	    int flags, struct filecaps *fcaps);
int	falloc_noinstall(struct thread *td, struct file **resultfp);
void	_finstall(struct filedesc *fdp, struct file *fp, int fd, int flags,
	    struct filecaps *fcaps);
int	finstall(struct thread *td, struct file *fp, int *resultfd, int flags,
	    struct filecaps *fcaps);
int	fdalloc(struct thread *td, int minfd, int *result);
int	fdallocn(struct thread *td, int minfd, int *fds, int n);
int	fdcheckstd(struct thread *td);
void	fdclose(struct thread *td, struct file *fp, int idx);
void	fdcloseexec(struct thread *td);
void	fdsetugidsafety(struct thread *td);
struct	filedesc *fdcopy(struct filedesc *fdp);
int	fdcopy_remapped(struct filedesc *fdp, const int *fds, size_t nfds,
	    struct filedesc **newfdp);
void	fdinstall_remapped(struct thread *td, struct filedesc *fdp);
void	fdunshare(struct thread *td);
void	fdescfree(struct thread *td);
void	fdescfree_remapped(struct filedesc *fdp);
struct	filedesc *fdinit(struct filedesc *fdp, bool prepfiles);
struct	filedesc *fdshare(struct filedesc *fdp);
struct filedesc_to_leader *
	filedesc_to_leader_alloc(struct filedesc_to_leader *old,
	    struct filedesc *fdp, struct proc *leader);
int	getvnode(struct thread *td, int fd, cap_rights_t *rightsp,
	    struct file **fpp);
void	mountcheckdirs(struct vnode *olddp, struct vnode *newdp);

/* Return a referenced file from an unlocked descriptor. */
int	fget_unlocked(struct filedesc *fdp, int fd, cap_rights_t *needrightsp,
	    struct file **fpp, seq_t *seqp);

/* Requires a FILEDESC_{S,X}LOCK held and returns without a ref. */
static __inline struct file *
fget_locked(struct filedesc *fdp, int fd)
{

	FILEDESC_LOCK_ASSERT(fdp);

	if (fd < 0 || fd > fdp->fd_lastfile)
		return (NULL);

	return (fdp->fd_ofiles[fd].fde_file);
}

static __inline bool
fd_modified(struct filedesc *fdp, int fd, seq_t seq)
{

	return (!seq_consistent(fd_seq(fdp->fd_files, fd), seq));
}

/* cdir/rdir/jdir manipulation functions. */
void	pwd_chdir(struct thread *td, struct vnode *vp);
int	pwd_chroot(struct thread *td, struct vnode *vp);
void	pwd_ensure_dirs(void);

#endif /* _KERNEL */

#endif /* !_SYS_FILEDESC_H_ */