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  * 4. Neither the name of the University nor the names of its contributors
   14  *    may be used to endorse or promote products derived from this software
   15  *    without specific prior written permission.
   16  *
   17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   27  * SUCH DAMAGE.
   28  *
   29  *      @(#)filedesc.h  8.1 (Berkeley) 6/2/93
   30  * $FreeBSD: releng/9.0/sys/sys/filedesc.h 224778 2011-08-11 12:30:23Z rwatson $
   31  */
   32 
   33 #ifndef _SYS_FILEDESC_H_
   34 #define _SYS_FILEDESC_H_
   35 
   36 #include <sys/queue.h>
   37 #include <sys/event.h>
   38 #include <sys/lock.h>
   39 #include <sys/priority.h>
   40 #include <sys/sx.h>
   41 
   42 #include <machine/_limits.h>
   43 
   44 /*
   45  * This structure is used for the management of descriptors.  It may be
   46  * shared by multiple processes.
   47  */
   48 #define NDSLOTTYPE      u_long
   49 
   50 struct filedesc {
   51         struct  file **fd_ofiles;       /* file structures for open files */
   52         char    *fd_ofileflags;         /* per-process open file flags */
   53         struct  vnode *fd_cdir;         /* current directory */
   54         struct  vnode *fd_rdir;         /* root directory */
   55         struct  vnode *fd_jdir;         /* jail root directory */
   56         int     fd_nfiles;              /* number of open files allocated */
   57         NDSLOTTYPE *fd_map;             /* bitmap of free fds */
   58         int     fd_lastfile;            /* high-water mark of fd_ofiles */
   59         int     fd_freefile;            /* approx. next free file */
   60         u_short fd_cmask;               /* mask for file creation */
   61         u_short fd_refcnt;              /* thread reference count */
   62         u_short fd_holdcnt;             /* hold count on structure + mutex */
   63         struct  sx fd_sx;               /* protects members of this struct */
   64         struct  kqlist fd_kqlist;       /* list of kqueues on this filedesc */
   65         int     fd_holdleaderscount;    /* block fdfree() for shared close() */
   66         int     fd_holdleaderswakeup;   /* fdfree() needs wakeup */
   67 };
   68 
   69 /*
   70  * Structure to keep track of (process leader, struct fildedesc) tuples.
   71  * Each process has a pointer to such a structure when detailed tracking
   72  * is needed, e.g., when rfork(RFPROC | RFMEM) causes a file descriptor
   73  * table to be shared by processes having different "p_leader" pointers
   74  * and thus distinct POSIX style locks.
   75  *
   76  * fdl_refcount and fdl_holdcount are protected by struct filedesc mtx.
   77  */
   78 struct filedesc_to_leader {
   79         int             fdl_refcount;   /* references from struct proc */
   80         int             fdl_holdcount;  /* temporary hold during closef */
   81         int             fdl_wakeup;     /* fdfree() waits on closef() */
   82         struct proc     *fdl_leader;    /* owner of POSIX locks */
   83         /* Circular list: */
   84         struct filedesc_to_leader *fdl_prev;
   85         struct filedesc_to_leader *fdl_next;
   86 };
   87 
   88 /*
   89  * Per-process open flags.
   90  */
   91 #define UF_EXCLOSE      0x01            /* auto-close on exec */
   92 
   93 #ifdef _KERNEL
   94 
   95 /* Lock a file descriptor table. */
   96 #define FILEDESC_LOCK_INIT(fdp) sx_init(&(fdp)->fd_sx, "filedesc structure")
   97 #define FILEDESC_LOCK_DESTROY(fdp)      sx_destroy(&(fdp)->fd_sx)
   98 #define FILEDESC_LOCK(fdp)      (&(fdp)->fd_sx)
   99 #define FILEDESC_XLOCK(fdp)     sx_xlock(&(fdp)->fd_sx)
  100 #define FILEDESC_XUNLOCK(fdp)   sx_xunlock(&(fdp)->fd_sx)
  101 #define FILEDESC_SLOCK(fdp)     sx_slock(&(fdp)->fd_sx)
  102 #define FILEDESC_SUNLOCK(fdp)   sx_sunlock(&(fdp)->fd_sx)
  103 
  104 #define FILEDESC_LOCK_ASSERT(fdp)       sx_assert(&(fdp)->fd_sx, SX_LOCKED | \
  105                                             SX_NOTRECURSED)
  106 #define FILEDESC_XLOCK_ASSERT(fdp)      sx_assert(&(fdp)->fd_sx, SX_XLOCKED | \
  107                                             SX_NOTRECURSED)
  108 
  109 struct thread;
  110 
  111 int     closef(struct file *fp, struct thread *td);
  112 int     dupfdopen(struct thread *td, struct filedesc *fdp, int indx, int dfd,
  113             int mode, int error);
  114 int     falloc(struct thread *td, struct file **resultfp, int *resultfd,
  115             int flags);
  116 int     falloc_noinstall(struct thread *td, struct file **resultfp);
  117 int     finstall(struct thread *td, struct file *fp, int *resultfp, int flags);
  118 int     fdalloc(struct thread *td, int minfd, int *result);
  119 int     fdavail(struct thread *td, int n);
  120 int     fdcheckstd(struct thread *td);
  121 void    fdclose(struct filedesc *fdp, struct file *fp, int idx, struct thread *td);
  122 void    fdcloseexec(struct thread *td);
  123 struct  filedesc *fdcopy(struct filedesc *fdp);
  124 void    fdunshare(struct proc *p, struct thread *td);
  125 void    fdfree(struct thread *td);
  126 struct  filedesc *fdinit(struct filedesc *fdp);
  127 struct  filedesc *fdshare(struct filedesc *fdp);
  128 struct filedesc_to_leader *
  129         filedesc_to_leader_alloc(struct filedesc_to_leader *old,
  130             struct filedesc *fdp, struct proc *leader);
  131 int     getvnode(struct filedesc *fdp, int fd, cap_rights_t rights,
  132             struct file **fpp);
  133 void    mountcheckdirs(struct vnode *olddp, struct vnode *newdp);
  134 void    setugidsafety(struct thread *td);
  135 
  136 /* Return a referenced file from an unlocked descriptor. */
  137 struct file *fget_unlocked(struct filedesc *fdp, int fd);
  138 
  139 /* Requires a FILEDESC_{S,X}LOCK held and returns without a ref. */
  140 static __inline struct file *
  141 fget_locked(struct filedesc *fdp, int fd)
  142 {
  143 
  144         return (fd < 0 || fd >= fdp->fd_nfiles ? NULL : fdp->fd_ofiles[fd]);
  145 }
  146 
  147 #endif /* _KERNEL */
  148 
  149 #endif /* !_SYS_FILEDESC_H_ */

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