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/10.4/sys/sys/filedesc.h 321020 2017-07-15 17:25:40Z dchagin $
   31  */
   32 
   33 #ifndef _SYS_FILEDESC_H_
   34 #define _SYS_FILEDESC_H_
   35 
   36 #include <sys/caprights.h>
   37 #include <sys/queue.h>
   38 #include <sys/event.h>
   39 #include <sys/lock.h>
   40 #include <sys/priority.h>
   41 #include <sys/seq.h>
   42 #include <sys/sx.h>
   43 
   44 #include <machine/_limits.h>
   45 
   46 struct filecaps {
   47         cap_rights_t     fc_rights;     /* per-descriptor capability rights */
   48         u_long          *fc_ioctls;     /* per-descriptor allowed ioctls */
   49         int16_t          fc_nioctls;    /* fc_ioctls array size */
   50         uint32_t         fc_fcntls;     /* per-descriptor allowed fcntls */
   51 };
   52 
   53 struct filedescent {
   54         struct file     *fde_file;      /* file structure for open file */
   55         struct filecaps  fde_caps;      /* per-descriptor rights */
   56         uint8_t          fde_flags;     /* per-process open file flags */
   57         seq_t            fde_seq;       /* keep file and caps in sync */
   58 };
   59 #define fde_rights      fde_caps.fc_rights
   60 #define fde_fcntls      fde_caps.fc_fcntls
   61 #define fde_ioctls      fde_caps.fc_ioctls
   62 #define fde_nioctls     fde_caps.fc_nioctls
   63 #define fde_change_size (offsetof(struct filedescent, fde_seq))
   64 
   65 /*
   66  * This structure is used for the management of descriptors.  It may be
   67  * shared by multiple processes.
   68  */
   69 #define NDSLOTTYPE      u_long
   70 
   71 struct filedesc {
   72         struct  filedescent *fd_ofiles; /* open files */
   73         struct  vnode *fd_cdir;         /* current directory */
   74         struct  vnode *fd_rdir;         /* root directory */
   75         struct  vnode *fd_jdir;         /* jail root directory */
   76         int     fd_nfiles;              /* number of open files allocated */
   77         NDSLOTTYPE *fd_map;             /* bitmap of free fds */
   78         int     fd_lastfile;            /* high-water mark of fd_ofiles */
   79         int     fd_freefile;            /* approx. next free file */
   80         u_short fd_cmask;               /* mask for file creation */
   81         u_short fd_refcnt;              /* thread reference count */
   82         u_short fd_holdcnt;             /* hold count on structure + mutex */
   83         struct  sx fd_sx;               /* protects members of this struct */
   84         struct  kqlist fd_kqlist;       /* list of kqueues on this filedesc */
   85         int     fd_holdleaderscount;    /* block fdfree() for shared close() */
   86         int     fd_holdleaderswakeup;   /* fdfree() needs wakeup */
   87 };
   88 #define fd_seq(fdp, fd) (&(fdp)->fd_ofiles[(fd)].fde_seq)
   89 
   90 /*
   91  * Structure to keep track of (process leader, struct fildedesc) tuples.
   92  * Each process has a pointer to such a structure when detailed tracking
   93  * is needed, e.g., when rfork(RFPROC | RFMEM) causes a file descriptor
   94  * table to be shared by processes having different "p_leader" pointers
   95  * and thus distinct POSIX style locks.
   96  *
   97  * fdl_refcount and fdl_holdcount are protected by struct filedesc mtx.
   98  */
   99 struct filedesc_to_leader {
  100         int             fdl_refcount;   /* references from struct proc */
  101         int             fdl_holdcount;  /* temporary hold during closef */
  102         int             fdl_wakeup;     /* fdfree() waits on closef() */
  103         struct proc     *fdl_leader;    /* owner of POSIX locks */
  104         /* Circular list: */
  105         struct filedesc_to_leader *fdl_prev;
  106         struct filedesc_to_leader *fdl_next;
  107 };
  108 
  109 /*
  110  * Per-process open flags.
  111  */
  112 #define UF_EXCLOSE      0x01            /* auto-close on exec */
  113 
  114 #ifdef _KERNEL
  115 
  116 /* Flags for do_dup() */
  117 #define DUP_FIXED       0x1     /* Force fixed allocation. */
  118 #define DUP_FCNTL       0x2     /* fcntl()-style errors. */
  119 #define DUP_CLOEXEC     0x4     /* Atomically set FD_CLOEXEC. */
  120 
  121 /* Lock a file descriptor table. */
  122 #define FILEDESC_LOCK_INIT(fdp) sx_init(&(fdp)->fd_sx, "filedesc structure")
  123 #define FILEDESC_LOCK_DESTROY(fdp)      sx_destroy(&(fdp)->fd_sx)
  124 #define FILEDESC_LOCK(fdp)      (&(fdp)->fd_sx)
  125 #define FILEDESC_XLOCK(fdp)     sx_xlock(&(fdp)->fd_sx)
  126 #define FILEDESC_XUNLOCK(fdp)   sx_xunlock(&(fdp)->fd_sx)
  127 #define FILEDESC_SLOCK(fdp)     sx_slock(&(fdp)->fd_sx)
  128 #define FILEDESC_SUNLOCK(fdp)   sx_sunlock(&(fdp)->fd_sx)
  129 
  130 #define FILEDESC_LOCK_ASSERT(fdp)       sx_assert(&(fdp)->fd_sx, SX_LOCKED | \
  131                                             SX_NOTRECURSED)
  132 #define FILEDESC_XLOCK_ASSERT(fdp)      sx_assert(&(fdp)->fd_sx, SX_XLOCKED | \
  133                                             SX_NOTRECURSED)
  134 #define FILEDESC_UNLOCK_ASSERT(fdp)     sx_assert(&(fdp)->fd_sx, SX_UNLOCKED)
  135 
  136 struct thread;
  137 
  138 void    filecaps_init(struct filecaps *fcaps);
  139 void    filecaps_copy(const struct filecaps *src, struct filecaps *dst);
  140 void    filecaps_move(struct filecaps *src, struct filecaps *dst);
  141 void    filecaps_free(struct filecaps *fcaps);
  142 
  143 int     closef(struct file *fp, struct thread *td);
  144 int     do_dup(struct thread *td, int flags, int old, int new,
  145             register_t *retval);
  146 int     dupfdopen(struct thread *td, struct filedesc *fdp, int dfd, int mode,
  147             int openerror, int *indxp);
  148 int     falloc(struct thread *td, struct file **resultfp, int *resultfd,
  149             int flags);
  150 int     falloc_noinstall(struct thread *td, struct file **resultfp);
  151 int     finstall(struct thread *td, struct file *fp, int *resultfp, int flags,
  152             struct filecaps *fcaps);
  153 int     fdalloc(struct thread *td, int minfd, int *result);
  154 int     fdallocn(struct thread *td, int minfd, int *fds, int n);
  155 int     fdavail(struct thread *td, int n);
  156 int     fdcheckstd(struct thread *td);
  157 void    fdclose(struct thread *td, struct file *fp, int idx);
  158 void    fdcloseexec(struct thread *td);
  159 struct  filedesc *fdcopy(struct filedesc *fdp);
  160 void    fdunshare(struct thread *td);
  161 void    fdescfree(struct thread *td);
  162 struct  filedesc *fdinit(struct filedesc *fdp);
  163 struct  filedesc *fdshare(struct filedesc *fdp);
  164 struct filedesc_to_leader *
  165         filedesc_to_leader_alloc(struct filedesc_to_leader *old,
  166             struct filedesc *fdp, struct proc *leader);
  167 int     getvnode(struct filedesc *fdp, int fd, cap_rights_t *rightsp,
  168             struct file **fpp);
  169 void    mountcheckdirs(struct vnode *olddp, struct vnode *newdp);
  170 void    setugidsafety(struct thread *td);
  171 
  172 /* Return a referenced file from an unlocked descriptor. */
  173 int     fget_unlocked(struct filedesc *fdp, int fd, cap_rights_t *needrightsp,
  174             int needfcntl, struct file **fpp, cap_rights_t *haverightsp);
  175 
  176 /* Requires a FILEDESC_{S,X}LOCK held and returns without a ref. */
  177 static __inline struct file *
  178 fget_locked(struct filedesc *fdp, int fd)
  179 {
  180 
  181         FILEDESC_LOCK_ASSERT(fdp);
  182 
  183         if (fd < 0 || fd > fdp->fd_lastfile)
  184                 return (NULL);
  185 
  186         return (fdp->fd_ofiles[fd].fde_file);
  187 }
  188 
  189 #endif /* _KERNEL */
  190 
  191 #endif /* !_SYS_FILEDESC_H_ */

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