1/* $NetBSD: filedesc.h,v 1.73 2025/07/16 19:14:14 kre Exp $ */
2
3/*-
4 * Copyright (c) 2008 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
17 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
18 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
19 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
20 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
21 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
22 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
23 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
24 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
25 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
26 * POSSIBILITY OF SUCH DAMAGE.
27 */
28
29/*
30 * Copyright (c) 1990, 1993
31 * The Regents of the University of California. All rights reserved.
32 *
33 * Redistribution and use in source and binary forms, with or without
34 * modification, are permitted provided that the following conditions
35 * are met:
36 * 1. Redistributions of source code must retain the above copyright
37 * notice, this list of conditions and the following disclaimer.
38 * 2. Redistributions in binary form must reproduce the above copyright
39 * notice, this list of conditions and the following disclaimer in the
40 * documentation and/or other materials provided with the distribution.
41 * 3. Neither the name of the University nor the names of its contributors
42 * may be used to endorse or promote products derived from this software
43 * without specific prior written permission.
44 *
45 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
46 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
47 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
48 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
49 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
50 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
51 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
52 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
53 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
54 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
55 * SUCH DAMAGE.
56 *
57 * @(#)filedesc.h 8.1 (Berkeley) 6/2/93
58 */
59
60#ifndef _SYS_FILEDESC_H_
61#define _SYS_FILEDESC_H_
62
63#include <sys/param.h>
64#include <sys/queue.h>
65#include <sys/mutex.h>
66#include <sys/rwlock.h>
67#include <sys/condvar.h>
68
69/*
70 * This structure is used for the management of descriptors. It may be
71 * shared by multiple processes.
72 *
73 * A process is initially started out with NDFILE descriptors stored within
74 * this structure, selected to be enough for typical applications based on
75 * the historical limit of 20 open files (and the usage of descriptors by
76 * shells). If these descriptors are exhausted, a larger descriptor table
77 * may be allocated, up to a process' resource limit; the internal arrays
78 * are then unused. The initial expansion is set to NDEXTENT; each time
79 * it runs out, it is doubled until the resource limit is reached. NDEXTENT
80 * should be selected to be the biggest multiple of OFILESIZE (see below)
81 * that will fit in a power-of-two sized piece of memory.
82 */
83#define NDFILE 20
84#define NDEXTENT 50 /* 250 bytes in 256-byte alloc */
85#define NDENTRIES 32 /* 32 fds per entry */
86#define NDENTRYMASK (NDENTRIES - 1)
87#define NDENTRYSHIFT 5 /* bits per entry */
88#define NDLOSLOTS(x) (((x) + NDENTRIES - 1) >> NDENTRYSHIFT)
89#define NDHISLOTS(x) ((NDLOSLOTS(x) + NDENTRIES - 1) >> NDENTRYSHIFT)
90#define NDFDFILE 6 /* first 6 descriptors are free */
91
92/*
93 * Process-private descriptor reference, one for each descriptor slot
94 * in use. Locks:
95 *
96 * : unlocked
97 * a atomic operations + filedesc_t::fd_lock in some cases
98 * d filedesc_t::fd_lock
99 *
100 * Note that ff_exclose and ff_allocated are likely to be byte sized
101 * (bool). In general adjacent sub-word sized fields must be locked
102 * the same way, but in this case it's ok: ff_exclose can only be
103 * modified while the descriptor slot is live, and ff_allocated when
104 * it's invalid.
105 *
106 * NOTE: ff_exclose should generally be set with fd_set_exclose(), not
107 * written to directly, when implementing flags like O_CLOEXEC or
108 * SOCK_CLOEXEC, so that struct filedesc::fd_exclose is updated as
109 * needed. See PR kern/58822: close-on-exec is broken for dup3 and
110 * opening cloning devices (fixed).
111 * Same with fd_set_foclose() for O_CLOFORK, SOCK_CLOFORK, etc.
112 */
113typedef struct fdfile {
114 bool ff_exclose; /* :: close on exec (fd_set_exclose) */
115 bool ff_foclose; /* :: close on fork (fd_set_foclose) */
116 bool ff_allocated; /* d: descriptor slot is allocated */
117 u_int ff_refcnt; /* a: reference count on structure */
118 struct file *ff_file; /* d: pointer to file if open */
119 SLIST_HEAD(,knote) ff_knlist; /* d: knotes attached to this fd */
120 kcondvar_t ff_closing; /* d: notifier for close */
121} fdfile_t;
122
123#define FDFILE_SIZE ((sizeof(fdfile_t)+CACHE_LINE_SIZE-1)/CACHE_LINE_SIZE*CACHE_LINE_SIZE)
124
125/* Reference count */
126#define FR_CLOSING (0x80000000) /* closing: must interlock */
127#define FR_MASK (~FR_CLOSING) /* reference count */
128
129/*
130 * Open file table, potentially many 'active' tables per filedesc_t
131 * in a multi-threaded process, or with a shared filedesc_t (clone()).
132 * nfiles is first to avoid pointer arithmetic.
133 */
134typedef struct fdtab {
135 u_int dt_nfiles; /* number of open files allocated */
136 struct fdtab *dt_link; /* for lists of dtab */
137 fdfile_t *dt_ff[NDFILE]; /* file structures for open fds */
138} fdtab_t;
139
140typedef struct filedesc {
141 /*
142 * Built-in fdfile_t records first, since they have strict
143 * alignment requirements.
144 */
145 uint8_t fd_dfdfile[NDFDFILE][FDFILE_SIZE];
146 /*
147 * All of the remaining fields are locked by fd_lock.
148 */
149 kmutex_t fd_lock; /* lock on structure */
150 fdtab_t * volatile fd_dt; /* active descriptor table */
151 uint32_t *fd_himap; /* each bit points to 32 fds */
152 uint32_t *fd_lomap; /* bitmap of free fds */
153 struct klist *fd_knhash; /* hash of attached non-fd knotes */
154 int fd_lastkqfile; /* max descriptor for kqueue */
155 int fd_lastfile; /* high-water mark of fd_ofiles */
156 int fd_refcnt; /* reference count */
157 u_long fd_knhashmask; /* size of fd_knhash */
158 int fd_freefile; /* approx. next free file */
159 int fd_unused; /* unused */
160 bool fd_exclose; /* non-zero if >0 fd with EXCLOSE */
161 bool fd_foclose; /* non-zero if >0 fd with FOCLOSE */
162 /*
163 * This structure is used when the number of open files is
164 * <= NDFILE, and are then pointed to by the pointers above.
165 */
166 fdtab_t fd_dtbuiltin;
167 /*
168 * These arrays are used when the number of open files is
169 * <= 1024, and are then pointed to by the pointers above.
170 */
171#define fd_startzero fd_dhimap /* area to zero on return to cache */
172 uint32_t fd_dhimap[NDENTRIES >> NDENTRYSHIFT];
173 uint32_t fd_dlomap[NDENTRIES];
174} filedesc_t;
175
176/*
177 * Working directory, root and umask information. Serialization:
178 *
179 * a atomic operations
180 * l cwdi_lock
181 */
182typedef struct cwdinfo {
183 struct vnode *cwdi_cdir; /* l: current directory */
184 struct vnode *cwdi_rdir; /* l: root directory */
185 struct vnode *cwdi_edir; /* l: emulation root (if known) */
186 u_int cwdi_cmask; /* a: mask for file creation */
187 u_int cwdi_refcnt; /* a: reference count */
188
189 krwlock_t cwdi_lock /* :: lock on struct */
190 __aligned(COHERENCY_UNIT); /* -> gets own cache line */
191} cwdinfo_t;
192
193#ifdef _KERNEL
194
195struct fileops;
196struct socket;
197struct proc;
198
199extern struct cwdinfo cwdi0;
200
201/*
202 * Kernel global variables and routines.
203 */
204void fd_sys_init(void);
205int fd_open(const char*, int, int, int*);
206int fd_dupopen(int, bool, int, int *);
207int fd_alloc(struct proc *, int, int *);
208void fd_tryexpand(struct proc *);
209int fd_allocfile(file_t **, int *);
210void fd_affix(struct proc *, file_t *, unsigned);
211void fd_abort(struct proc *, file_t *, unsigned);
212filedesc_t *fd_copy(void);
213filedesc_t *fd_init(filedesc_t *);
214void fd_share(proc_t *);
215void fd_hold(lwp_t *);
216void fd_free(void);
217void fd_closeexec(void);
218void fd_ktrexecfd(void);
219int fd_checkstd(void);
220file_t *fd_getfile(unsigned);
221file_t *fd_getfile2(proc_t *, unsigned);
222void fd_putfile(unsigned);
223int fd_getvnode(unsigned, file_t **);
224int fd_getsock(unsigned, struct socket **);
225int fd_getsock1(unsigned, struct socket **, file_t **);
226void fd_putvnode(unsigned);
227void fd_putsock(unsigned);
228int fd_close(unsigned);
229int fd_dup(file_t *, int, int *, bool, bool);
230int fd_dup2(file_t *, unsigned, int);
231int fd_clone(file_t *, unsigned, int, const struct fileops *, void *);
232void fd_set_exclose(struct lwp *, int, bool);
233void fd_set_foclose(struct lwp *, int, bool);
234int pipe1(struct lwp *, int *, int);
235int dodup(struct lwp *, int, int, int, register_t *);
236
237void cwd_sys_init(void);
238struct cwdinfo *cwdinit(void);
239void cwdshare(proc_t *);
240void cwdunshare(proc_t *);
241void cwdfree(struct cwdinfo *);
242void cwdexec(struct proc *);
243
244#define GETCWD_CHECK_ACCESS 0x0001
245int getcwd_common(struct vnode *, struct vnode *, char **, char *, int,
246 int, struct lwp *);
247int vnode_to_path(char *, size_t, struct vnode *, struct lwp *,
248 struct proc *);
249
250int closef(file_t *);
251file_t *fgetdummy(void);
252void fputdummy(file_t *);
253
254struct stat;
255int do_sys_fstat(int, struct stat *);
256struct flock;
257int do_fcntl_lock(int, int, struct flock *);
258int do_posix_fadvise(int, off_t, off_t, int);
259
260extern kmutex_t filelist_lock;
261extern filedesc_t filedesc0;
262
263#endif /* _KERNEL */
264
265#endif /* !_SYS_FILEDESC_H_ */