FreeBSD/Linux Kernel Cross Reference
sys/sys/filedesc.h
1 /*
2 * Copyright (c) 1990, 1993
3 * The Regents of the University of California. All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 3. All advertising materials mentioning features or use of this software
14 * must display the following acknowledgement:
15 * This product includes software developed by the University of
16 * California, Berkeley and its contributors.
17 * 4. Neither the name of the University nor the names of its contributors
18 * may be used to endorse or promote products derived from this software
19 * without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 *
33 * @(#)filedesc.h 8.1 (Berkeley) 6/2/93
34 * $FreeBSD$
35 */
36
37 #ifndef _SYS_FILEDESC_H_
38 #define _SYS_FILEDESC_H_
39
40 #include <sys/queue.h>
41
42 /*
43 * This structure is used for the management of descriptors. It may be
44 * shared by multiple processes.
45 *
46 * A process is initially started out with NDFILE descriptors stored within
47 * this structure, selected to be enough for typical applications based on
48 * the historical limit of 20 open files (and the usage of descriptors by
49 * shells). If these descriptors are exhausted, a larger descriptor table
50 * may be allocated, up to a process' resource limit; the internal arrays
51 * are then unused. The initial expansion is set to NDEXTENT; each time
52 * it runs out, it is doubled until the resource limit is reached. NDEXTENT
53 * should be selected to be the biggest multiple of OFILESIZE (see below)
54 * that will fit in a power-of-two sized piece of memory.
55 */
56 #define NDFILE 20
57 #define NDEXTENT 50 /* 250 bytes in 256-byte alloc. */
58
59 struct klist;
60
61 struct filedesc {
62 struct file **fd_ofiles; /* file structures for open files */
63 char *fd_ofileflags; /* per-process open file flags */
64 struct vnode *fd_cdir; /* current directory */
65 struct vnode *fd_rdir; /* root directory */
66 struct vnode *fd_jdir; /* jail root directory */
67 int fd_nfiles; /* number of open files allocated */
68 u_int fd_lastfile; /* high-water mark of fd_ofiles */
69 u_int fd_freefile; /* approx. next free file */
70 u_short fd_cmask; /* mask for file creation */
71 u_short fd_refcnt; /* reference count */
72
73 int fd_knlistsize; /* size of knlist */
74 struct klist *fd_knlist; /* list of attached knotes */
75 u_long fd_knhashmask; /* size of knhash */
76 struct klist *fd_knhash; /* hash table for attached knotes */
77 int fd_holdleaderscount; /* block fdfree() for shared close() */
78 int fd_holdleaderswakeup; /* fdfree() needs wakeup */
79 };
80
81 /*
82 * Basic allocation of descriptors:
83 * one of the above, plus arrays for NDFILE descriptors.
84 */
85 struct filedesc0 {
86 struct filedesc fd_fd;
87 /*
88 * These arrays are used when the number of open files is
89 * <= NDFILE, and are then pointed to by the pointers above.
90 */
91 struct file *fd_dfiles[NDFILE];
92 char fd_dfileflags[NDFILE];
93 };
94
95
96
97 /*
98 * Structure to keep track of (process leader, struct fildedesc) tuples.
99 * Each process has a pointer to such a structure when detailed tracking
100 * is needed. e.g. when rfork(RFPROC | RFMEM) causes a file descriptor
101 * table to be shared by processes having different "p_leader" pointers
102 * and thus distinct POSIX style locks.
103 */
104 struct filedesc_to_leader {
105 int fdl_refcount; /* references from struct proc */
106 int fdl_holdcount; /* temporary hold during closef */
107 int fdl_wakeup; /* fdfree() waits on closef() */
108 struct proc *fdl_leader; /* owner of POSIX locks */
109 /* Circular list */
110 struct filedesc_to_leader *fdl_prev;
111 struct filedesc_to_leader *fdl_next;
112 };
113
114 /*
115 * Per-process open flags.
116 */
117 #define UF_EXCLOSE 0x01 /* auto-close on exec */
118 #if 0
119 #define UF_MAPPED 0x02 /* mapped from device */
120 #endif
121
122 /*
123 * Storage required per open file descriptor.
124 */
125 #define OFILESIZE (sizeof(struct file *) + sizeof(char))
126
127 /*
128 * This structure that holds the information needed to send a SIGIO or
129 * a SIGURG signal to a process or process group when new data arrives
130 * on a device or socket. The structure is placed on an SLIST belonging
131 * to the proc or pgrp so that the entire list may be revoked when the
132 * process exits or the process group disappears.
133 */
134 struct sigio {
135 union {
136 struct proc *siu_proc; /* process to receive SIGIO/SIGURG */
137 struct pgrp *siu_pgrp; /* process group to receive ... */
138 } sio_u;
139 SLIST_ENTRY(sigio) sio_pgsigio; /* sigio's for process or group */
140 struct sigio **sio_myref; /* location of the pointer that holds
141 * the reference to this structure */
142 struct ucred *sio_ucred; /* current credentials */
143 uid_t sio_ruid; /* real user id */
144 pid_t sio_pgid; /* pgid for signals */
145 };
146 #define sio_proc sio_u.siu_proc
147 #define sio_pgrp sio_u.siu_pgrp
148
149 SLIST_HEAD(sigiolst, sigio);
150
151 #ifdef _KERNEL
152 /*
153 * Kernel global variables and routines.
154 */
155 int dupfdopen __P((struct proc *, struct filedesc *, int, int, int, int));
156 int fdalloc __P((struct proc *p, int want, int *result));
157 int fdavail __P((struct proc *p, int n));
158 int falloc __P((struct proc *p, struct file **resultfp, int *resultfd));
159 void ffree __P((struct file *));
160 struct filedesc *fdinit __P((struct proc *p));
161 struct filedesc *fdshare __P((struct proc *p));
162 struct filedesc *fdcopy __P((struct proc *p));
163 void fdfree __P((struct proc *p));
164 int closef __P((struct file *fp,struct proc *p));
165 void fdcloseexec __P((struct proc *p));
166 int fdcheckstd __P((struct proc *p));
167 struct file *holdfp __P((struct filedesc* fdp, int fd, int flag));
168 int getvnode __P((struct filedesc *fdp, int fd, struct file **fpp));
169 int fdissequential __P((struct file *));
170 void fdsequential __P((struct file *, int));
171 pid_t fgetown __P((struct sigio *));
172 int fsetown __P((pid_t, struct sigio **));
173 void funsetown __P((struct sigio *));
174 void funsetownlst __P((struct sigiolst *));
175 void setugidsafety __P((struct proc *p));
176
177 struct filedesc_to_leader *
178 filedesc_to_leader_alloc(struct filedesc_to_leader *old,
179 struct proc *leader);
180
181 #endif
182
183 #endif
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