The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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

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    1 /*
    2  * Copyright (c) 1990, 1993
    3  *      The Regents of the University of California.  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  8.1 (Berkeley) 6/2/93
   34  * $FreeBSD$
   35  */
   36 
   37 #ifndef _SYS_FILEDESC_H_
   38 #define _SYS_FILEDESC_H_
   39 
   40 #include <sys/queue.h>
   41 
   42 /*
   43  * This structure is used for the management of descriptors.  It may be
   44  * shared by multiple processes.
   45  *
   46  * A process is initially started out with NDFILE descriptors stored within
   47  * this structure, selected to be enough for typical applications based on
   48  * the historical limit of 20 open files (and the usage of descriptors by
   49  * shells).  If these descriptors are exhausted, a larger descriptor table
   50  * may be allocated, up to a process' resource limit; the internal arrays
   51  * are then unused.  The initial expansion is set to NDEXTENT; each time
   52  * it runs out, it is doubled until the resource limit is reached. NDEXTENT
   53  * should be selected to be the biggest multiple of OFILESIZE (see below)
   54  * that will fit in a power-of-two sized piece of memory.
   55  */
   56 #define NDFILE          20
   57 #define NDEXTENT        50              /* 250 bytes in 256-byte alloc. */
   58 
   59 struct klist;
   60 
   61 struct filedesc {
   62         struct  file **fd_ofiles;       /* file structures for open files */
   63         char    *fd_ofileflags;         /* per-process open file flags */
   64         struct  vnode *fd_cdir;         /* current directory */
   65         struct  vnode *fd_rdir;         /* root directory */
   66         struct  vnode *fd_jdir;         /* jail root directory */
   67         int     fd_nfiles;              /* number of open files allocated */
   68         u_int   fd_lastfile;            /* high-water mark of fd_ofiles */
   69         u_int   fd_freefile;            /* approx. next free file */
   70         u_short fd_cmask;               /* mask for file creation */
   71         u_short fd_refcnt;              /* reference count */
   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         int     fd_holdleaderscount;    /* block fdfree() for shared close() */
   78         int     fd_holdleaderswakeup;   /* fdfree() needs wakeup */
   79 };
   80 
   81 /*
   82  * Basic allocation of descriptors:
   83  * one of the above, plus arrays for NDFILE descriptors.
   84  */
   85 struct filedesc0 {
   86         struct  filedesc fd_fd;
   87         /*
   88          * These arrays are used when the number of open files is
   89          * <= NDFILE, and are then pointed to by the pointers above.
   90          */
   91         struct  file *fd_dfiles[NDFILE];
   92         char    fd_dfileflags[NDFILE];
   93 };
   94 
   95 
   96 
   97 /*
   98  * Structure to keep track of (process leader, struct fildedesc) tuples.
   99  * Each process has a pointer to such a structure when detailed tracking
  100  * is needed. e.g. when rfork(RFPROC | RFMEM) causes a file descriptor
  101  * table to be shared by processes having different "p_leader" pointers
  102  * and thus distinct POSIX style locks.
  103  */
  104 struct filedesc_to_leader {
  105         int             fdl_refcount;   /* references from struct proc */
  106         int             fdl_holdcount;  /* temporary hold during closef */
  107         int             fdl_wakeup;     /* fdfree() waits on closef() */
  108         struct proc     *fdl_leader;    /* owner of POSIX locks */
  109         /* Circular list */
  110         struct filedesc_to_leader *fdl_prev;
  111         struct filedesc_to_leader *fdl_next;
  112 };
  113 
  114 /*
  115  * Per-process open flags.
  116  */
  117 #define UF_EXCLOSE      0x01            /* auto-close on exec */
  118 #if 0
  119 #define UF_MAPPED       0x02            /* mapped from device */
  120 #endif
  121 
  122 /*
  123  * Storage required per open file descriptor.
  124  */
  125 #define OFILESIZE (sizeof(struct file *) + sizeof(char))
  126 
  127 /*
  128  * This structure that holds the information needed to send a SIGIO or
  129  * a SIGURG signal to a process or process group when new data arrives
  130  * on a device or socket.  The structure is placed on an SLIST belonging
  131  * to the proc or pgrp so that the entire list may be revoked when the
  132  * process exits or the process group disappears.
  133  */
  134 struct  sigio {
  135         union {
  136                 struct  proc *siu_proc; /* process to receive SIGIO/SIGURG */
  137                 struct  pgrp *siu_pgrp; /* process group to receive ... */
  138         } sio_u;
  139         SLIST_ENTRY(sigio) sio_pgsigio; /* sigio's for process or group */
  140         struct  sigio **sio_myref;      /* location of the pointer that holds
  141                                          * the reference to this structure */
  142         struct  ucred *sio_ucred;       /* current credentials */
  143         uid_t   sio_ruid;               /* real user id */
  144         pid_t   sio_pgid;               /* pgid for signals */
  145 };
  146 #define sio_proc        sio_u.siu_proc
  147 #define sio_pgrp        sio_u.siu_pgrp
  148 
  149 SLIST_HEAD(sigiolst, sigio);
  150 
  151 #ifdef _KERNEL
  152 /*
  153  * Kernel global variables and routines.
  154  */
  155 int     dupfdopen __P((struct proc *, struct filedesc *, int, int, int, int));
  156 int     fdalloc __P((struct proc *p, int want, int *result));
  157 int     fdavail __P((struct proc *p, int n));
  158 int     falloc __P((struct proc *p, struct file **resultfp, int *resultfd));
  159 void    ffree __P((struct file *));
  160 struct  filedesc *fdinit __P((struct proc *p));
  161 struct  filedesc *fdshare __P((struct proc *p));
  162 struct  filedesc *fdcopy __P((struct proc *p));
  163 void    fdfree __P((struct proc *p));
  164 int     closef __P((struct file *fp,struct proc *p));
  165 void    fdcloseexec __P((struct proc *p));
  166 int     fdcheckstd __P((struct proc *p));
  167 struct  file *holdfp __P((struct filedesc* fdp, int fd, int flag));
  168 int     getvnode __P((struct filedesc *fdp, int fd, struct file **fpp));
  169 int     fdissequential __P((struct file *));
  170 void    fdsequential __P((struct file *, int));
  171 pid_t   fgetown __P((struct sigio *));
  172 int     fsetown __P((pid_t, struct sigio **));
  173 void    funsetown __P((struct sigio *));
  174 void    funsetownlst __P((struct sigiolst *));
  175 void    setugidsafety __P((struct proc *p));
  176 
  177 struct filedesc_to_leader *
  178 filedesc_to_leader_alloc(struct filedesc_to_leader *old,
  179                          struct proc *leader);
  180 
  181 #endif
  182 
  183 #endif

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