* Copyright (c) 1990 The Regents of the University of California.
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* @(#)filedesc.h 7.4 (Berkeley) 5/4/91
* This structure is used for the management of descriptors. It may be
* shared by multiple processes.
* A process is initially started out with NDFILE descriptors stored within
* this structure, selected to be enough for typical applications based on
* the historical limit of 20 open files (and the usage of descriptors by
* shells). If these descriptors are exhausted, a larger descriptor table
* may be allocated, up to a process' resource limit; the internal arrays
* are then unused. The initial expansion is set to NDEXTENT; each time
* it runs out, it is doubled until the resource limit is reached. NDEXTENT
* should be selected to be the biggest multiple of OFILESIZE (see below)
* that will fit in a power-of-two sized piece of memory.
#define NDEXTENT 50 /* 250 bytes in 256-byte alloc. */
struct file
**fd_ofiles
; /* file structures for open files */
char *fd_ofileflags
; /* per-process open file flags */
struct vnode
*fd_cdir
; /* current directory */
struct vnode
*fd_rdir
; /* root directory */
int fd_nfiles
; /* number of open files allocated */
u_short fd_lastfile
; /* high-water mark of fd_ofiles */
u_short fd_freefile
; /* approx. next free file */
u_short fd_cmask
; /* mask for file creation */
u_short fd_refcnt
; /* reference count */
* Basic allocation of descriptors:
* one of the above, plus arrays for NDFILE descriptors.
* These arrays are used when the number of open files is
* <= NDFILE, and are then pointed to by the pointers above.
struct file
*fd_dfiles
[NDFILE
];
char fd_dfileflags
[NDFILE
];
* Per-process open flags.
#define UF_EXCLOSE 0x01 /* auto-close on exec */
#define UF_MAPPED 0x02 /* mapped from device */
* Storage required per open file descriptor.
#define OFILESIZE (sizeof(struct file *) + sizeof(char))
* Kernel global variables and routines.
int fdalloc
__P((struct proc
*p
, int want
, int *result
));
int fdavail
__P((struct proc
*p
, int n
));
int falloc
__P((struct proc
*p
, struct file
**resultfp
, int *resultfd
));
struct filedesc
*fdcopy
__P((struct proc
*p
));
void fdfree
__P((struct proc
*p
));