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1.1 root 1: /*
2: * Copyright (c) 1990 The Regents of the University of California.
3: * 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 7.4 (Berkeley) 5/4/91
34: */
35:
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:
53: struct filedesc {
54: struct file **fd_ofiles; /* file structures for open files */
55: char *fd_ofileflags; /* per-process open file flags */
56: struct vnode *fd_cdir; /* current directory */
57: struct vnode *fd_rdir; /* root directory */
58: int fd_nfiles; /* number of open files allocated */
59: u_short fd_lastfile; /* high-water mark of fd_ofiles */
60: u_short fd_freefile; /* approx. next free file */
61: u_short fd_cmask; /* mask for file creation */
62: u_short fd_refcnt; /* reference count */
63: };
64:
65: /*
66: * Basic allocation of descriptors:
67: * one of the above, plus arrays for NDFILE descriptors.
68: */
69: struct filedesc0 {
70: struct filedesc fd_fd;
71: /*
72: * These arrays are used when the number of open files is
73: * <= NDFILE, and are then pointed to by the pointers above.
74: */
75: struct file *fd_dfiles[NDFILE];
76: char fd_dfileflags[NDFILE];
77: };
78:
79: /*
80: * Per-process open flags.
81: */
82: #define UF_EXCLOSE 0x01 /* auto-close on exec */
83: #define UF_MAPPED 0x02 /* mapped from device */
84:
85: /*
86: * Storage required per open file descriptor.
87: */
88: #define OFILESIZE (sizeof(struct file *) + sizeof(char))
89:
90: #ifdef KERNEL
91: /*
92: * Kernel global variables and routines.
93: */
94: int fdalloc __P((struct proc *p, int want, int *result));
95: int fdavail __P((struct proc *p, int n));
96: int falloc __P((struct proc *p, struct file **resultfp, int *resultfd));
97: struct filedesc *fdcopy __P((struct proc *p));
98: void fdfree __P((struct proc *p));
99: #endif
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