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Annotation of sys/sys/filedesc.h, Revision 1.1

1.1     ! nbrk        1: /*     $OpenBSD: filedesc.h,v 1.19 2004/07/22 06:11:10 tedu Exp $      */
        !             2: /*     $NetBSD: filedesc.h,v 1.14 1996/04/09 20:55:28 cgd Exp $        */
        !             3:
        !             4: /*
        !             5:  * Copyright (c) 1990, 1993
        !             6:  *     The Regents of the University of California.  All rights reserved.
        !             7:  *
        !             8:  * Redistribution and use in source and binary forms, with or without
        !             9:  * modification, are permitted provided that the following conditions
        !            10:  * are met:
        !            11:  * 1. Redistributions of source code must retain the above copyright
        !            12:  *    notice, this list of conditions and the following disclaimer.
        !            13:  * 2. Redistributions in binary form must reproduce the above copyright
        !            14:  *    notice, this list of conditions and the following disclaimer in the
        !            15:  *    documentation and/or other materials provided with the distribution.
        !            16:  * 3. Neither the name of the University nor the names of its contributors
        !            17:  *    may be used to endorse or promote products derived from this software
        !            18:  *    without specific prior written permission.
        !            19:  *
        !            20:  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
        !            21:  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
        !            22:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
        !            23:  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
        !            24:  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
        !            25:  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
        !            26:  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
        !            27:  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
        !            28:  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
        !            29:  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
        !            30:  * SUCH DAMAGE.
        !            31:  *
        !            32:  *     @(#)filedesc.h  8.1 (Berkeley) 6/2/93
        !            33:  */
        !            34:
        !            35: #include <sys/rwlock.h>
        !            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: #define NDENTRIES      32              /* 32 fds per entry */
        !            53: #define NDENTRYMASK    (NDENTRIES - 1)
        !            54: #define NDENTRYSHIFT   5               /* bits per entry */
        !            55: #define NDREDUCE(x)    (((x) + NDENTRIES - 1) >> NDENTRYSHIFT)
        !            56: #define NDHISLOTS(x)   (NDREDUCE(NDREDUCE(x)))
        !            57: #define NDLOSLOTS(x)   (NDHISLOTS(x) << NDENTRYSHIFT)
        !            58:
        !            59: struct filedesc {
        !            60:        struct  file **fd_ofiles;       /* file structures for open files */
        !            61:        char    *fd_ofileflags;         /* per-process open file flags */
        !            62:        struct  vnode *fd_cdir;         /* current directory */
        !            63:        struct  vnode *fd_rdir;         /* root directory */
        !            64:        int     fd_nfiles;              /* number of open files allocated */
        !            65:        u_int   *fd_himap;              /* each bit points to 32 fds */
        !            66:        u_int   *fd_lomap;              /* bitmap of free fds */
        !            67:        int     fd_lastfile;            /* high-water mark of fd_ofiles */
        !            68:        int     fd_freefile;            /* approx. next free file */
        !            69:        u_short fd_cmask;               /* mask for file creation */
        !            70:        u_short fd_refcnt;              /* reference count */
        !            71:        struct rwlock fd_lock;          /* lock for the file descs */
        !            72:
        !            73:        int     fd_knlistsize;          /* size of knlist */
        !            74:        struct  klist *fd_knlist;       /* list of attached knotes */
        !            75:        u_long  fd_knhashmask;          /* size of knhash */
        !            76:        struct  klist *fd_knhash;       /* hash table for attached knotes */
        !            77: };
        !            78:
        !            79: /*
        !            80:  * Basic allocation of descriptors:
        !            81:  * one of the above, plus arrays for NDFILE descriptors.
        !            82:  */
        !            83: struct filedesc0 {
        !            84:        struct  filedesc fd_fd;
        !            85:        /*
        !            86:         * These arrays are used when the number of open files is
        !            87:         * <= NDFILE, and are then pointed to by the pointers above.
        !            88:         */
        !            89:        struct  file *fd_dfiles[NDFILE];
        !            90:        char    fd_dfileflags[NDFILE];
        !            91:        /*
        !            92:         * There arrays are used when the number of open files is
        !            93:         * <= 1024, and are then pointed to by the pointers above.
        !            94:         */
        !            95:        u_int   fd_dhimap[NDENTRIES >> NDENTRYSHIFT];
        !            96:        u_int   fd_dlomap[NDENTRIES];
        !            97: };
        !            98:
        !            99: /*
        !           100:  * Per-process open flags.
        !           101:  */
        !           102: #define        UF_EXCLOSE      0x01            /* auto-close on exec */
        !           103:
        !           104: /*
        !           105:  * Storage required per open file descriptor.
        !           106:  */
        !           107: #define OFILESIZE (sizeof(struct file *) + sizeof(char))
        !           108:
        !           109: #ifdef _KERNEL
        !           110: /*
        !           111:  * Kernel global variables and routines.
        !           112:  */
        !           113: void   filedesc_init(void);
        !           114: int    dupfdopen(struct filedesc *fdp, int indx, int dfd, int mode,
        !           115:            int error);
        !           116: int    fdalloc(struct proc *p, int want, int *result);
        !           117: void   fdexpand(struct proc *);
        !           118: int    falloc(struct proc *p, struct file **resultfp, int *resultfd);
        !           119: struct filedesc *fdinit(struct proc *p);
        !           120: struct filedesc *fdshare(struct proc *p);
        !           121: struct filedesc *fdcopy(struct proc *p);
        !           122: void   fdfree(struct proc *p);
        !           123: int    fdrelease(struct proc *p, int);
        !           124: void   fdremove(struct filedesc *, int);
        !           125: void   fdcloseexec(struct proc *);
        !           126: struct file *fd_getfile(struct filedesc *, int fd);
        !           127:
        !           128: int    closef(struct file *, struct proc *);
        !           129: int    getsock(struct filedesc *, int, struct file **);
        !           130:
        !           131: #define        fdplock(fdp)    rw_enter_write(&(fdp)->fd_lock)
        !           132: #define        fdpunlock(fdp)  rw_exit_write(&(fdp)->fd_lock)
        !           133: #endif

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