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/* $NetBSD: filedesc.h,v 1.70.2.1 2024/11/17 16:16:10 martin Exp $ */
/*-
* Copyright (c) 2008 The NetBSD Foundation, Inc.
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
*/
/*
* 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. 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
*/
#ifndef _SYS_FILEDESC_H_
#define _SYS_FILEDESC_H_
#include <sys/param.h>
#include <sys/queue.h>
#include <sys/mutex.h>
#include <sys/rwlock.h>
#include <sys/condvar.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 */
#define NDENTRIES 32 /* 32 fds per entry */
#define NDENTRYMASK (NDENTRIES - 1)
#define NDENTRYSHIFT 5 /* bits per entry */
#define NDLOSLOTS(x) (((x) + NDENTRIES - 1) >> NDENTRYSHIFT)
#define NDHISLOTS(x) ((NDLOSLOTS(x) + NDENTRIES - 1) >> NDENTRYSHIFT)
#define NDFDFILE 6 /* first 6 descriptors are free */
/*
* Process-private descriptor reference, one for each descriptor slot
* in use. Locks:
*
* : unlocked
* a atomic operations + filedesc_t::fd_lock in some cases
* d filedesc_t::fd_lock
*
* Note that ff_exclose and ff_allocated are likely to be byte sized
* (bool). In general adjacent sub-word sized fields must be locked
* the same way, but in this case it's ok: ff_exclose can only be
* modified while the descriptor slot is live, and ff_allocated when
* it's invalid.
*
* NOTE: ff_exclose should generally be set with fd_set_exclose(), not
* written to directly, when implementing flags like O_CLOEXEC or
* SOCK_CLOEXEC, so that struct filedesc::fd_exclose is updated as
* needed. See PR kern/58855: close-on-exec is broken for dup3 and
* opening cloning devices.
*/
typedef struct fdfile {
bool ff_exclose; /* :: close on exec (fd_set_exclose) */
bool ff_allocated; /* d: descriptor slot is allocated */
u_int ff_refcnt; /* a: reference count on structure */
struct file *ff_file; /* d: pointer to file if open */
SLIST_HEAD(,knote) ff_knlist; /* d: knotes attached to this fd */
kcondvar_t ff_closing; /* d: notifier for close */
} fdfile_t;
#define FDFILE_SIZE ((sizeof(fdfile_t)+CACHE_LINE_SIZE-1)/CACHE_LINE_SIZE*CACHE_LINE_SIZE)
/* Reference count */
#define FR_CLOSING (0x80000000) /* closing: must interlock */
#define FR_MASK (~FR_CLOSING) /* reference count */
/*
* Open file table, potentially many 'active' tables per filedesc_t
* in a multi-threaded process, or with a shared filedesc_t (clone()).
* nfiles is first to avoid pointer arithmetic.
*/
typedef struct fdtab {
u_int dt_nfiles; /* number of open files allocated */
struct fdtab *dt_link; /* for lists of dtab */
fdfile_t *dt_ff[NDFILE]; /* file structures for open fds */
} fdtab_t;
typedef struct filedesc {
/*
* Built-in fdfile_t records first, since they have strict
* alignment requirements.
*/
uint8_t fd_dfdfile[NDFDFILE][FDFILE_SIZE];
/*
* All of the remaining fields are locked by fd_lock.
*/
kmutex_t fd_lock; /* lock on structure */
fdtab_t * volatile fd_dt; /* active descriptor table */
uint32_t *fd_himap; /* each bit points to 32 fds */
uint32_t *fd_lomap; /* bitmap of free fds */
struct klist *fd_knhash; /* hash of attached non-fd knotes */
int fd_lastkqfile; /* max descriptor for kqueue */
int fd_lastfile; /* high-water mark of fd_ofiles */
int fd_refcnt; /* reference count */
u_long fd_knhashmask; /* size of fd_knhash */
int fd_freefile; /* approx. next free file */
int fd_unused; /* unused */
bool fd_exclose; /* non-zero if >0 fd with EXCLOSE */
/*
* This structure is used when the number of open files is
* <= NDFILE, and are then pointed to by the pointers above.
*/
fdtab_t fd_dtbuiltin;
/*
* These arrays are used when the number of open files is
* <= 1024, and are then pointed to by the pointers above.
*/
#define fd_startzero fd_dhimap /* area to zero on return to cache */
uint32_t fd_dhimap[NDENTRIES >> NDENTRYSHIFT];
uint32_t fd_dlomap[NDENTRIES];
} filedesc_t;
/*
* Working directory, root and umask information. Serialization:
*
* a atomic operations
* l cwdi_lock
*/
typedef struct cwdinfo {
struct vnode *cwdi_cdir; /* l: current directory */
struct vnode *cwdi_rdir; /* l: root directory */
struct vnode *cwdi_edir; /* l: emulation root (if known) */
u_int cwdi_cmask; /* a: mask for file creation */
u_int cwdi_refcnt; /* a: reference count */
krwlock_t cwdi_lock /* :: lock on struct */
__aligned(COHERENCY_UNIT); /* -> gets own cache line */
} cwdinfo_t;
#ifdef _KERNEL
struct fileops;
struct socket;
struct proc;
extern struct cwdinfo cwdi0;
/*
* Kernel global variables and routines.
*/
void fd_sys_init(void);
int fd_open(const char*, int, int, int*);
int fd_dupopen(int, bool, int, int *);
int fd_alloc(struct proc *, int, int *);
void fd_tryexpand(struct proc *);
int fd_allocfile(file_t **, int *);
void fd_affix(struct proc *, file_t *, unsigned);
void fd_abort(struct proc *, file_t *, unsigned);
filedesc_t *fd_copy(void);
filedesc_t *fd_init(filedesc_t *);
void fd_share(proc_t *);
void fd_hold(lwp_t *);
void fd_free(void);
void fd_closeexec(void);
void fd_ktrexecfd(void);
int fd_checkstd(void);
file_t *fd_getfile(unsigned);
file_t *fd_getfile2(proc_t *, unsigned);
void fd_putfile(unsigned);
int fd_getvnode(unsigned, file_t **);
int fd_getsock(unsigned, struct socket **);
int fd_getsock1(unsigned, struct socket **, file_t **);
void fd_putvnode(unsigned);
void fd_putsock(unsigned);
int fd_close(unsigned);
int fd_dup(file_t *, int, int *, bool);
int fd_dup2(file_t *, unsigned, int);
int fd_clone(file_t *, unsigned, int, const struct fileops *, void *);
void fd_set_exclose(struct lwp *, int, bool);
int pipe1(struct lwp *, int *, int);
int dodup(struct lwp *, int, int, int, register_t *);
void cwd_sys_init(void);
struct cwdinfo *cwdinit(void);
void cwdshare(proc_t *);
void cwdunshare(proc_t *);
void cwdfree(struct cwdinfo *);
void cwdexec(struct proc *);
#define GETCWD_CHECK_ACCESS 0x0001
int getcwd_common(struct vnode *, struct vnode *, char **, char *, int,
int, struct lwp *);
int vnode_to_path(char *, size_t, struct vnode *, struct lwp *,
struct proc *);
int closef(file_t *);
file_t *fgetdummy(void);
void fputdummy(file_t *);
struct stat;
int do_sys_fstat(int, struct stat *);
struct flock;
int do_fcntl_lock(int, int, struct flock *);
int do_posix_fadvise(int, off_t, off_t, int);
extern kmutex_t filelist_lock;
extern filedesc_t filedesc0;
#endif /* _KERNEL */
#endif /* !_SYS_FILEDESC_H_ */
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