projects / unix-history / blame
| Commit | Line | Data |
|---|---|---|
| b688fc87 WJ |
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 |