1 /* $OpenBSD: filedesc.h,v 1.19 2004/07/22 06:11:10 tedu Exp $ */
2 /* $NetBSD: filedesc.h,v 1.14 1996/04/09 20:55:28 cgd Exp $ */
3
4 /*
5 * Copyright (c) 1990, 1993
6 * The Regents of the University of California. All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 3. Neither the name of the University nor the names of its contributors
17 * may be used to endorse or promote products derived from this software
18 * without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 *
32 * @(#)filedesc.h 8.1 (Berkeley) 6/2/93
33 */
34
35 #include <sys/rwlock.h>
36 /*
37 * This structure is used for the management of descriptors. It may be
38 * shared by multiple processes.
39 *
40 * A process is initially started out with NDFILE descriptors stored within
41 * this structure, selected to be enough for typical applications based on
42 * the historical limit of 20 open files (and the usage of descriptors by
43 * shells). If these descriptors are exhausted, a larger descriptor table
44 * may be allocated, up to a process' resource limit; the internal arrays
45 * are then unused. The initial expansion is set to NDEXTENT; each time
46 * it runs out, it is doubled until the resource limit is reached. NDEXTENT
47 * should be selected to be the biggest multiple of OFILESIZE (see below)
48 * that will fit in a power-of-two sized piece of memory.
49 */
50 #define NDFILE 20
51 #define NDEXTENT 50 /* 250 bytes in 256-byte alloc. */
52 #define NDENTRIES 32 /* 32 fds per entry */
53 #define NDENTRYMASK (NDENTRIES - 1)
54 #define NDENTRYSHIFT 5 /* bits per entry */
55 #define NDREDUCE(x) (((x) + NDENTRIES - 1) >> NDENTRYSHIFT)
56 #define NDHISLOTS(x) (NDREDUCE(NDREDUCE(x)))
57 #define NDLOSLOTS(x) (NDHISLOTS(x) << NDENTRYSHIFT)
58
59 struct filedesc {
60 struct file **fd_ofiles; /* file structures for open files */
61 char *fd_ofileflags; /* per-process open file flags */
62 struct vnode *fd_cdir; /* current directory */
63 struct vnode *fd_rdir; /* root directory */
64 int fd_nfiles; /* number of open files allocated */
65 u_int *fd_himap; /* each bit points to 32 fds */
66 u_int *fd_lomap; /* bitmap of free fds */
67 int fd_lastfile; /* high-water mark of fd_ofiles */
68 int fd_freefile; /* approx. next free file */
69 u_short fd_cmask; /* mask for file creation */
70 u_short fd_refcnt; /* reference count */
71 struct rwlock fd_lock; /* lock for the file descs */
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 };
78
79 /*
80 * Basic allocation of descriptors:
81 * one of the above, plus arrays for NDFILE descriptors.
82 */
83 struct filedesc0 {
84 struct filedesc fd_fd;
85 /*
86 * These arrays are used when the number of open files is
87 * <= NDFILE, and are then pointed to by the pointers above.
88 */
89 struct file *fd_dfiles[NDFILE];
90 char fd_dfileflags[NDFILE];
91 /*
92 * There arrays are used when the number of open files is
93 * <= 1024, and are then pointed to by the pointers above.
94 */
95 u_int fd_dhimap[NDENTRIES >> NDENTRYSHIFT];
96 u_int fd_dlomap[NDENTRIES];
97 };
98
99 /*
100 * Per-process open flags.
101 */
102 #define UF_EXCLOSE 0x01 /* auto-close on exec */
103
104 /*
105 * Storage required per open file descriptor.
106 */
107 #define OFILESIZE (sizeof(struct file *) + sizeof(char))
108
109 #ifdef _KERNEL
110 /*
111 * Kernel global variables and routines.
112 */
113 void filedesc_init(void);
114 int dupfdopen(struct filedesc *fdp, int indx, int dfd, int mode,
115 int error);
116 int fdalloc(struct proc *p, int want, int *result);
117 void fdexpand(struct proc *);
118 int falloc(struct proc *p, struct file **resultfp, int *resultfd);
119 struct filedesc *fdinit(struct proc *p);
120 struct filedesc *fdshare(struct proc *p);
121 struct filedesc *fdcopy(struct proc *p);
122 void fdfree(struct proc *p);
123 int fdrelease(struct proc *p, int);
124 void fdremove(struct filedesc *, int);
125 void fdcloseexec(struct proc *);
126 struct file *fd_getfile(struct filedesc *, int fd);
127
128 int closef(struct file *, struct proc *);
129 int getsock(struct filedesc *, int, struct file **);
130
131 #define fdplock(fdp) rw_enter_write(&(fdp)->fd_lock)
132 #define fdpunlock(fdp) rw_exit_write(&(fdp)->fd_lock)
133 #endif