FreeBSD/Linux Kernel Cross Reference
sys/sys/filedesc.h

     /*
      * Copyright (c) 1990, 1993
      *      The Regents of the University of California.  All rights reserved.
      *
      * Redistribution and use in source and binary forms, with or without
      * modification, are permitted provided that the following conditions
      * are met:
      * 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
     * SUCH DAMAGE.
     *
     *      @(#)filedesc.h  8.1 (Berkeley) 6/2/93
     * $FreeBSD: src/sys/sys/filedesc.h,v 1.8.4.2 2000/01/25 18:09:10 dillon Exp $
     */
    
    #ifndef _SYS_FILEDESC_H_
    #define _SYS_FILEDESC_H_
    
    /*
     * 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 NDFILE          20
    #define NDEXTENT        50              /* 250 bytes in 256-byte alloc. */
    
    struct filedesc {
            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.
     */
    struct filedesc0 {
            struct  filedesc fd_fd;
            /*
             * 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))
    
    #ifdef KERNEL
    /*
     * Kernel global variables and routines.
     */
    int     dupfdopen __P((struct filedesc *, int, int, int, int));
    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));
   void    ffree __P((struct file *));
   struct  filedesc *fdinit __P((struct proc *p));
   struct  filedesc *fdshare __P((struct proc *p));
   struct  filedesc *fdcopy __P((struct proc *p));
   void    fdfree __P((struct proc *p));
   int     closef __P((struct file *fp,struct proc *p));
   void    fdcloseexec __P((struct proc *p));
   int     getvnode __P((struct filedesc *fdp, int fd, struct file **fpp));
   void    setugidsafety __P((struct proc *p));
   #endif
   
   #endif

Cache object: 58e8b7d6e811516e3ca55d0c58b81a44