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: releng/5.0/sys/sys/filedesc.h 104393 2002-10-03 02:13:00Z truckman $
35 */
36
37 #ifndef _SYS_FILEDESC_H_
38 #define _SYS_FILEDESC_H_
39
40 #include <sys/_lock.h>
41 #include <sys/_mutex.h>
42 #include <sys/queue.h>
43
44 /*
45 * This structure is used for the management of descriptors. It may be
46 * shared by multiple processes.
47 *
48 * A process is initially started out with NDFILE descriptors stored within
49 * this structure, selected to be enough for typical applications based on
50 * the historical limit of 20 open files (and the usage of descriptors by
51 * shells). If these descriptors are exhausted, a larger descriptor table
52 * may be allocated, up to a process' resource limit; the internal arrays
53 * are then unused. The initial expansion is set to NDEXTENT; each time
54 * it runs out, it is doubled until the resource limit is reached. NDEXTENT
55 * should be selected to be the biggest multiple of OFILESIZE (see below)
56 * that will fit in a power-of-two sized piece of memory.
57 */
58 #define NDFILE 20
59 #define NDEXTENT 50 /* 250 bytes in 256-byte alloc. */
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 int fd_lastfile; /* high-water mark of fd_ofiles */
69 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 struct mtx fd_mtx; /* mtx to protect the members of struct filedesc */
78 };
79
80 /*
81 * Basic allocation of descriptors:
82 * one of the above, plus arrays for NDFILE descriptors.
83 */
84 struct filedesc0 {
85 struct filedesc fd_fd;
86 /*
87 * These arrays are used when the number of open files is
88 * <= NDFILE, and are then pointed to by the pointers above.
89 */
90 struct file *fd_dfiles[NDFILE];
91 char fd_dfileflags[NDFILE];
92 };
93
94 /*
95 * Per-process open flags.
96 */
97 #define UF_EXCLOSE 0x01 /* auto-close on exec */
98 #if 0
99 #define UF_MAPPED 0x02 /* mapped from device */
100 #endif
101
102 /*
103 * Storage required per open file descriptor.
104 */
105 #define OFILESIZE (sizeof(struct file *) + sizeof(char))
106
107 /*
108 * This structure holds the information needed to send a SIGIO or
109 * a SIGURG signal to a process or process group when new data arrives
110 * on a device or socket. The structure is placed on an SLIST belonging
111 * to the proc or pgrp so that the entire list may be revoked when the
112 * process exits or the process group disappears.
113 *
114 * (c) const
115 * (pg) locked by either the process or process group lock
116 */
117 struct sigio {
118 union {
119 struct proc *siu_proc; /* (c) process to receive SIGIO/SIGURG */
120 struct pgrp *siu_pgrp; /* (c) process group to receive ... */
121 } sio_u;
122 SLIST_ENTRY(sigio) sio_pgsigio; /* (pg) sigio's for process or group */
123 struct sigio **sio_myref; /* (c) location of the pointer that holds
124 * the reference to this structure */
125 struct ucred *sio_ucred; /* (c) current credentials */
126 pid_t sio_pgid; /* (c) pgid for signals */
127 };
128 #define sio_proc sio_u.siu_proc
129 #define sio_pgrp sio_u.siu_pgrp
130
131 SLIST_HEAD(sigiolst, sigio);
132
133 #ifdef _KERNEL
134
135 #define FILEDESC_LOCK_DESC "filedesc structure"
136
137 /* Lock a file descriptor table. */
138 #define FILEDESC_LOCK(fd) mtx_lock(&(fd)->fd_mtx)
139 #define FILEDESC_UNLOCK(fd) mtx_unlock(&(fd)->fd_mtx)
140 #define FILEDESC_LOCKED(fd) mtx_owned(&(fd)->fd_mtx)
141 #define FILEDESC_LOCK_ASSERT(fd, type) mtx_assert(&(fd)->fd_mtx, (type))
142
143 int closef(struct file *fp, struct thread *p);
144 int dupfdopen(struct thread *td, struct filedesc *fdp, int indx, int dfd,
145 int mode, int error);
146 int falloc(struct thread *p, struct file **resultfp, int *resultfd);
147 int fdalloc(struct thread *p, int want, int *result);
148 int fdavail(struct thread *td, int n);
149 void fdcloseexec(struct thread *td);
150 int fdcheckstd(struct thread *td);
151 struct filedesc *fdcopy(struct thread *td);
152 void fdfree(struct thread *td);
153 struct filedesc *fdinit(struct thread *td);
154 struct filedesc *fdshare(struct proc *p);
155 void ffree(struct file *fp);
156 static __inline struct file * fget_locked(struct filedesc *fdp, int fd);
157 pid_t fgetown(struct sigio **sigiop);
158 int fsetown(pid_t pgid, struct sigio **sigiop);
159 void funsetown(struct sigio **sigiop);
160 void funsetownlst(struct sigiolst *sigiolst);
161 int getvnode(struct filedesc *fdp, int fd, struct file **fpp);
162 void setugidsafety(struct thread *td);
163
164 static __inline struct file *
165 fget_locked(struct filedesc *fdp, int fd)
166 {
167
168 /* u_int cast checks for negative descriptors. */
169 return ((u_int)fd >= (u_int)fdp->fd_nfiles ? NULL : fdp->fd_ofiles[fd]);
170 }
171
172 #endif /* _KERNEL */
173
174 #endif /* !_SYS_FILEDESC_H_ */
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