2 * Copyright (c) 1990, 1993
3 * The Regents of the University of California. All rights reserved.
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6 * modification, are permitted provided that the following conditions
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14 * must display the following acknowledgement:
15 * This product includes software developed by the University of
16 * California, Berkeley and its contributors.
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18 * may be used to endorse or promote products derived from this software
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33 * @(#)filedesc.h 8.1 (Berkeley) 6/2/93
34 * $Id: filedesc.h,v 1.12 1997/10/12 20:25:57 phk Exp $
37 #ifndef _SYS_FILEDESC_H_
38 #define _SYS_FILEDESC_H_
41 * This structure is used for the management of descriptors. It may be
42 * shared by multiple processes.
44 * A process is initially started out with NDFILE descriptors stored within
45 * this structure, selected to be enough for typical applications based on
46 * the historical limit of 20 open files (and the usage of descriptors by
47 * shells). If these descriptors are exhausted, a larger descriptor table
48 * may be allocated, up to a process' resource limit; the internal arrays
49 * are then unused. The initial expansion is set to NDEXTENT; each time
50 * it runs out, it is doubled until the resource limit is reached. NDEXTENT
51 * should be selected to be the biggest multiple of OFILESIZE (see below)
52 * that will fit in a power-of-two sized piece of memory.
55 #define NDEXTENT 50 /* 250 bytes in 256-byte alloc. */
58 struct file **fd_ofiles; /* file structures for open files */
59 char *fd_ofileflags; /* per-process open file flags */
60 struct vnode *fd_cdir; /* current directory */
61 struct vnode *fd_rdir; /* root directory */
62 int fd_nfiles; /* number of open files allocated */
63 u_short fd_lastfile; /* high-water mark of fd_ofiles */
64 u_short fd_freefile; /* approx. next free file */
65 u_short fd_cmask; /* mask for file creation */
66 u_short fd_refcnt; /* reference count */
70 * Basic allocation of descriptors:
71 * one of the above, plus arrays for NDFILE descriptors.
74 struct filedesc fd_fd;
76 * These arrays are used when the number of open files is
77 * <= NDFILE, and are then pointed to by the pointers above.
79 struct file *fd_dfiles[NDFILE];
80 char fd_dfileflags[NDFILE];
84 * Per-process open flags.
86 #define UF_EXCLOSE 0x01 /* auto-close on exec */
87 #define UF_MAPPED 0x02 /* mapped from device */
90 * Storage required per open file descriptor.
92 #define OFILESIZE (sizeof(struct file *) + sizeof(char))
96 * Kernel global variables and routines.
98 int dupfdopen __P((struct filedesc *, int, int, int, int));
99 int fdalloc __P((struct proc *p, int want, int *result));
100 int fdavail __P((struct proc *p, int n));
101 int falloc __P((struct proc *p, struct file **resultfp, int *resultfd));
102 void ffree __P((struct file *));
103 struct filedesc *fdinit __P((struct proc *p));
104 struct filedesc *fdshare __P((struct proc *p));
105 struct filedesc *fdcopy __P((struct proc *p));
106 void fdfree __P((struct proc *p));
107 int closef __P((struct file *fp,struct proc *p));
108 void fdcloseexec __P((struct proc *p));
109 int getvnode __P((struct filedesc *fdp, int fd, struct file **fpp));
110 int fdissequential __P((struct file *));
111 void fdsequential __P((struct file *, int));