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/5.1/sys/sys/filedesc.h 110906 2003-02-15 05:52:56Z alfred $
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 #ifdef _KERNEL
108
109 #define FILEDESC_LOCK_DESC "filedesc structure"
110
111 /* Lock a file descriptor table. */
112 #define FILEDESC_LOCK(fd) mtx_lock(&(fd)->fd_mtx)
113 #define FILEDESC_UNLOCK(fd) mtx_unlock(&(fd)->fd_mtx)
114 #define FILEDESC_LOCKED(fd) mtx_owned(&(fd)->fd_mtx)
115 #define FILEDESC_LOCK_ASSERT(fd, type) mtx_assert(&(fd)->fd_mtx, (type))
116
117 int closef(struct file *fp, struct thread *p);
118 int dupfdopen(struct thread *td, struct filedesc *fdp, int indx, int dfd,
119 int mode, int error);
120 int falloc(struct thread *p, struct file **resultfp, int *resultfd);
121 int fdalloc(struct thread *p, int want, int *result);
122 int fdavail(struct thread *td, int n);
123 void fdcloseexec(struct thread *td);
124 int fdcheckstd(struct thread *td);
125 struct filedesc *fdcopy(struct filedesc *fdp);
126 void fdfree(struct thread *td);
127 struct filedesc *fdinit(struct filedesc *fdp);
128 struct filedesc *fdshare(struct filedesc *fdp);
129 void ffree(struct file *fp);
130 static __inline struct file * fget_locked(struct filedesc *fdp, int fd);
131 int getvnode(struct filedesc *fdp, int fd, struct file **fpp);
132 void setugidsafety(struct thread *td);
133
134 static __inline struct file *
135 fget_locked(struct filedesc *fdp, int fd)
136 {
137
138 /* u_int cast checks for negative descriptors. */
139 return ((u_int)fd >= (u_int)fdp->fd_nfiles ? NULL : fdp->fd_ofiles[fd]);
140 }
141
142 extern struct mtx fdesc_mtx;
143
144 #endif /* _KERNEL */
145
146 #endif /* !_SYS_FILEDESC_H_ */
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