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

     /*      $OpenBSD: file.h,v 1.66 2022/06/20 01:39:44 visa Exp $  */
     /*      $NetBSD: file.h,v 1.11 1995/03/26 20:24:13 jtc Exp $    */
     
     /*
      * Copyright (c) 1982, 1986, 1989, 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. 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.
     *
     *      @(#)file.h      8.2 (Berkeley) 8/20/94
     */
    
    #ifndef _KERNEL
    #include <sys/fcntl.h>
    
    #else /* _KERNEL */
    #include <sys/queue.h>
    #include <sys/mutex.h>
    #endif /* _KERNEL */
    
    #define DTYPE_VNODE     1       /* file */
    #define DTYPE_SOCKET    2       /* communications endpoint */
    #define DTYPE_PIPE      3       /* pipe */
    #define DTYPE_KQUEUE    4       /* event queue */
    #define DTYPE_DMABUF    5       /* DMA buffer (for DRM) */
    #define DTYPE_SYNC      6       /* sync file (for DRM) */
    
    #ifdef _KERNEL
    struct proc;
    struct uio;
    struct knote;
    struct stat;
    struct file;
    struct ucred;
    
    /**
     * File operations.
     * The following entries could be called without KERNEL_LOCK hold:
     * - fo_read
     * - fo_write
     * - fo_close
     */
    struct  fileops {
            int     (*fo_read)(struct file *, struct uio *, int);
            int     (*fo_write)(struct file *, struct uio *, int);
            int     (*fo_ioctl)(struct file *, u_long, caddr_t, struct proc *);
            int     (*fo_kqfilter)(struct file *, struct knote *);
            int     (*fo_stat)(struct file *, struct stat *, struct proc *);
            int     (*fo_close)(struct file *, struct proc *);
            int     (*fo_seek)(struct file *, off_t *, int, struct proc *);
    };
    #define FO_POSITION     0x00000001      /* positioned read/write */
    
    /*
     * Kernel descriptor table.
     * One entry for each open kernel vnode and socket.
     *
     *  Locks used to protect struct members in this file:
     *      I       immutable after creation
     *      F       global `fhdlk' mutex
     *      a       atomic operations
     *      f       per file `f_mtx'
     *      v       vnode lock
     */
    struct file {
            LIST_ENTRY(file) f_list;/* [F] list of active files */
            struct mutex f_mtx;
            u_int   f_flag;         /* [a] see fcntl.h */
            u_int   f_iflags;       /* [a] internal flags */
            int     f_type;         /* [I] descriptor type */
            u_int   f_count;        /* [a] reference count */
            struct  ucred *f_cred;  /* [I] credentials associated with descriptor */
            const struct fileops *f_ops; /* [I] file operation pointers */
            off_t   f_offset;       /* [f,v] offset */
            void    *f_data;        /* [I] private data */
            uint64_t f_rxfer;       /* [f] total number of read transfers */
            uint64_t f_wxfer;       /* [f] total number of write transfers */
           uint64_t f_seek;        /* [f] total independent seek operations */
           uint64_t f_rbytes;      /* [f] total bytes read */
           uint64_t f_wbytes;      /* [f] total bytes written */
   };
   
   #define FIF_HASLOCK             0x01    /* descriptor holds advisory lock */
   #define FIF_INSERTED            0x80    /* present in `filehead' */
   
   #define FREF(fp) \
           do { \
                   extern void vfs_stall_barrier(void); \
                   vfs_stall_barrier(); \
                   atomic_inc_int(&(fp)->f_count); \
           } while (0)
   
   #define FRELE(fp,p) \
           (atomic_dec_int_nv(&fp->f_count) == 0 ? fdrop(fp, p) : 0)
   
   #define FDUP_MAX_COUNT          (UINT_MAX - 2 * MAXCPUS)
   
   int     fdrop(struct file *, struct proc *);
   
   static inline off_t
   foffset(struct file *fp)
   {
           off_t offset;
   
           mtx_enter(&fp->f_mtx);
           offset = fp->f_offset;
           mtx_leave(&fp->f_mtx);
           return (offset);
   }
   
   LIST_HEAD(filelist, file);
   extern int maxfiles;                    /* kernel limit on number of open files */
   extern int numfiles;                    /* actual number of open files */
   extern const struct fileops socketops;  /* socket operations for files */
   extern const struct fileops vnops;      /* vnode operations for files */
   
   #endif /* _KERNEL */

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