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/5.2/sys/sys/filedesc.h 122514 2003-11-11 22:07:29Z jhb $
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 int fd_holdleaderscount; /* block fdfree() for shared close() */
79 int fd_holdleaderswakeup; /* fdfree() needs wakeup */
80 };
81
82 /*
83 * Basic allocation of descriptors:
84 * one of the above, plus arrays for NDFILE descriptors.
85 */
86 struct filedesc0 {
87 struct filedesc fd_fd;
88 /*
89 * These arrays are used when the number of open files is
90 * <= NDFILE, and are then pointed to by the pointers above.
91 */
92 struct file *fd_dfiles[NDFILE];
93 char fd_dfileflags[NDFILE];
94 };
95
96
97
98 /*
99 * Structure to keep track of (process leader, struct fildedesc) tuples.
100 * Each process has a pointer to such a structure when detailed tracking
101 * is needed. e.g. when rfork(RFPROC | RFMEM) causes a file descriptor
102 * table to be shared by processes having different "p_leader" pointers
103 * and thus distinct POSIX style locks.
104 *
105 * fdl_refcount and fdl_holdcount are protected by struct filedesc mtx.
106 */
107 struct filedesc_to_leader {
108 int fdl_refcount; /* references from struct proc */
109 int fdl_holdcount; /* temporary hold during closef */
110 int fdl_wakeup; /* fdfree() waits on closef() */
111 struct proc *fdl_leader; /* owner of POSIX locks */
112 /* Circular list */
113 struct filedesc_to_leader *fdl_prev;
114 struct filedesc_to_leader *fdl_next;
115 };
116
117 /*
118 * Per-process open flags.
119 */
120 #define UF_EXCLOSE 0x01 /* auto-close on exec */
121 #if 0
122 #define UF_MAPPED 0x02 /* mapped from device */
123 #endif
124
125 /*
126 * Storage required per open file descriptor.
127 */
128 #define OFILESIZE (sizeof(struct file *) + sizeof(char))
129
130 #ifdef _KERNEL
131
132 #define FILEDESC_LOCK_DESC "filedesc structure"
133
134 /* Lock a file descriptor table. */
135 #define FILEDESC_LOCK(fd) mtx_lock(&(fd)->fd_mtx)
136 #define FILEDESC_UNLOCK(fd) mtx_unlock(&(fd)->fd_mtx)
137 #define FILEDESC_LOCKED(fd) mtx_owned(&(fd)->fd_mtx)
138 #define FILEDESC_LOCK_ASSERT(fd, type) mtx_assert(&(fd)->fd_mtx, (type))
139
140 struct thread;
141
142 int closef(struct file *fp, struct thread *p);
143 int dupfdopen(struct thread *td, struct filedesc *fdp, int indx, int dfd,
144 int mode, int error);
145 int falloc(struct thread *p, struct file **resultfp, int *resultfd);
146 int fdalloc(struct thread *p, int want, int *result);
147 int fdavail(struct thread *td, int n);
148 void fdcloseexec(struct thread *td);
149 int fdcheckstd(struct thread *td);
150 struct filedesc *fdcopy(struct filedesc *fdp);
151 void fdfree(struct thread *td);
152 struct filedesc *fdinit(struct filedesc *fdp);
153 struct filedesc *fdshare(struct filedesc *fdp);
154 void ffree(struct file *fp);
155 static __inline struct file * fget_locked(struct filedesc *fdp, int fd);
156 int getvnode(struct filedesc *fdp, int fd, struct file **fpp);
157 void setugidsafety(struct thread *td);
158
159 struct filedesc_to_leader *
160 filedesc_to_leader_alloc(struct filedesc_to_leader *old,
161 struct filedesc *fdp,
162 struct proc *leader);
163
164
165 static __inline struct file *
166 fget_locked(struct filedesc *fdp, int fd)
167 {
168
169 /* u_int cast checks for negative descriptors. */
170 return ((u_int)fd >= (u_int)fdp->fd_nfiles ? NULL : fdp->fd_ofiles[fd]);
171 }
172
173 extern struct mtx fdesc_mtx;
174
175 #endif /* _KERNEL */
176
177 #endif /* !_SYS_FILEDESC_H_ */
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