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

     /*-
      * SPDX-License-Identifier: BSD-3-Clause
      *
      * Copyright (c) 1990, 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.
     *
     *      @(#)filedesc.h  8.1 (Berkeley) 6/2/93
     * $FreeBSD$
     */
    
    #ifndef _SYS_FILEDESC_H_
    #define _SYS_FILEDESC_H_
    
    #include <sys/caprights.h>
    #include <sys/queue.h>
    #include <sys/event.h>
    #include <sys/lock.h>
    #include <sys/priority.h>
    #include <sys/seq.h>
    #include <sys/sx.h>
    
    #include <machine/_limits.h>
    
    struct filecaps {
            cap_rights_t     fc_rights;     /* per-descriptor capability rights */
            u_long          *fc_ioctls;     /* per-descriptor allowed ioctls */
            int16_t          fc_nioctls;    /* fc_ioctls array size */
            uint32_t         fc_fcntls;     /* per-descriptor allowed fcntls */
    };
    
    struct filedescent {
            struct file     *fde_file;      /* file structure for open file */
            struct filecaps  fde_caps;      /* per-descriptor rights */
            uint8_t          fde_flags;     /* per-process open file flags */
            seq_t            fde_seq;       /* keep file and caps in sync */
    };
    #define fde_rights      fde_caps.fc_rights
    #define fde_fcntls      fde_caps.fc_fcntls
    #define fde_ioctls      fde_caps.fc_ioctls
    #define fde_nioctls     fde_caps.fc_nioctls
    #define fde_change_size (offsetof(struct filedescent, fde_seq))
    
    struct fdescenttbl {
            int     fdt_nfiles;             /* number of open files allocated */
            struct  filedescent fdt_ofiles[0];      /* open files */
    };
    #define fd_seq(fdt, fd) (&(fdt)->fdt_ofiles[(fd)].fde_seq)
    
    /*
     * This structure is used for the management of descriptors.  It may be
     * shared by multiple processes.
     */
    #define NDSLOTTYPE      u_long
    
    struct filedesc {
            struct  fdescenttbl *fd_files;  /* open files table */
            struct  vnode *fd_cdir;         /* current directory */
            struct  vnode *fd_rdir;         /* root directory */
            struct  vnode *fd_jdir;         /* jail root directory */
            NDSLOTTYPE *fd_map;             /* bitmap of free fds */
            int     fd_lastfile;            /* high-water mark of fd_ofiles */
            int     fd_freefile;            /* approx. next free file */
            u_short fd_cmask;               /* mask for file creation */
            int     fd_refcnt;              /* thread reference count */
            int     fd_holdcnt;             /* hold count on structure + mutex */
            struct  sx fd_sx;               /* protects members of this struct */
            struct  kqlist fd_kqlist;       /* list of kqueues on this filedesc */
            int     fd_holdleaderscount;    /* block fdfree() for shared close() */
            int     fd_holdleaderswakeup;   /* fdfree() needs wakeup */
    };
    
    /*
     * Structure to keep track of (process leader, struct fildedesc) tuples.
     * Each process has a pointer to such a structure when detailed tracking
     * is needed, e.g., when rfork(RFPROC | RFMEM) causes a file descriptor
    * table to be shared by processes having different "p_leader" pointers
    * and thus distinct POSIX style locks.
    *
    * fdl_refcount and fdl_holdcount are protected by struct filedesc mtx.
    */
   struct filedesc_to_leader {
           int             fdl_refcount;   /* references from struct proc */
           int             fdl_holdcount;  /* temporary hold during closef */
           int             fdl_wakeup;     /* fdfree() waits on closef() */
           struct proc     *fdl_leader;    /* owner of POSIX locks */
           /* Circular list: */
           struct filedesc_to_leader *fdl_prev;
           struct filedesc_to_leader *fdl_next;
   };
   #define fd_nfiles       fd_files->fdt_nfiles
   #define fd_ofiles       fd_files->fdt_ofiles
   
   /*
    * Per-process open flags.
    */
   #define UF_EXCLOSE      0x01            /* auto-close on exec */
   
   #ifdef _KERNEL
   
   /* Lock a file descriptor table. */
   #define FILEDESC_LOCK_INIT(fdp) sx_init(&(fdp)->fd_sx, "filedesc structure")
   #define FILEDESC_LOCK_DESTROY(fdp)      sx_destroy(&(fdp)->fd_sx)
   #define FILEDESC_LOCK(fdp)      (&(fdp)->fd_sx)
   #define FILEDESC_XLOCK(fdp)     sx_xlock(&(fdp)->fd_sx)
   #define FILEDESC_XUNLOCK(fdp)   sx_xunlock(&(fdp)->fd_sx)
   #define FILEDESC_SLOCK(fdp)     sx_slock(&(fdp)->fd_sx)
   #define FILEDESC_SUNLOCK(fdp)   sx_sunlock(&(fdp)->fd_sx)
   
   #define FILEDESC_LOCK_ASSERT(fdp)       sx_assert(&(fdp)->fd_sx, SX_LOCKED | \
                                               SX_NOTRECURSED)
   #define FILEDESC_XLOCK_ASSERT(fdp)      sx_assert(&(fdp)->fd_sx, SX_XLOCKED | \
                                               SX_NOTRECURSED)
   #define FILEDESC_UNLOCK_ASSERT(fdp)     sx_assert(&(fdp)->fd_sx, SX_UNLOCKED)
   
   /* Operation types for kern_dup(). */
   enum {
           FDDUP_NORMAL,           /* dup() behavior. */
           FDDUP_FCNTL,            /* fcntl()-style errors. */
           FDDUP_FIXED,            /* Force fixed allocation. */
           FDDUP_MUSTREPLACE,      /* Target must exist. */
           FDDUP_LASTMODE,
   };
   
   /* Flags for kern_dup(). */
   #define FDDUP_FLAG_CLOEXEC      0x1     /* Atomically set UF_EXCLOSE. */
   
   /* For backward compatibility. */
   #define falloc(td, resultfp, resultfd, flags) \
           falloc_caps(td, resultfp, resultfd, flags, NULL)
   
   struct thread;
   
   void    filecaps_init(struct filecaps *fcaps);
   bool    filecaps_copy(const struct filecaps *src, struct filecaps *dst,
               bool locked);
   void    filecaps_move(struct filecaps *src, struct filecaps *dst);
   void    filecaps_free(struct filecaps *fcaps);
   
   int     closef(struct file *fp, struct thread *td);
   int     dupfdopen(struct thread *td, struct filedesc *fdp, int dfd, int mode,
               int openerror, int *indxp);
   int     falloc_caps(struct thread *td, struct file **resultfp, int *resultfd,
               int flags, struct filecaps *fcaps);
   int     falloc_noinstall(struct thread *td, struct file **resultfp);
   void    _finstall(struct filedesc *fdp, struct file *fp, int fd, int flags,
               struct filecaps *fcaps);
   int     finstall(struct thread *td, struct file *fp, int *resultfd, int flags,
               struct filecaps *fcaps);
   int     fdalloc(struct thread *td, int minfd, int *result);
   int     fdallocn(struct thread *td, int minfd, int *fds, int n);
   int     fdcheckstd(struct thread *td);
   void    fdclose(struct thread *td, struct file *fp, int idx);
   void    fdcloseexec(struct thread *td);
   void    fdsetugidsafety(struct thread *td);
   struct  filedesc *fdcopy(struct filedesc *fdp);
   int     fdcopy_remapped(struct filedesc *fdp, const int *fds, size_t nfds,
               struct filedesc **newfdp);
   void    fdinstall_remapped(struct thread *td, struct filedesc *fdp);
   void    fdunshare(struct thread *td);
   void    fdescfree(struct thread *td);
   void    fdescfree_remapped(struct filedesc *fdp);
   struct  filedesc *fdinit(struct filedesc *fdp, bool prepfiles);
   struct  filedesc *fdshare(struct filedesc *fdp);
   struct filedesc_to_leader *
           filedesc_to_leader_alloc(struct filedesc_to_leader *old,
               struct filedesc *fdp, struct proc *leader);
   int     getvnode(struct thread *td, int fd, cap_rights_t *rightsp,
               struct file **fpp);
   void    mountcheckdirs(struct vnode *olddp, struct vnode *newdp);
   
   int     fget_cap_locked(struct filedesc *fdp, int fd, cap_rights_t *needrightsp,
               struct file **fpp, struct filecaps *havecapsp);
   int     fget_cap(struct thread *td, int fd, cap_rights_t *needrightsp,
               struct file **fpp, struct filecaps *havecapsp);
   
   /* Return a referenced file from an unlocked descriptor. */
   int     fget_unlocked(struct filedesc *fdp, int fd, cap_rights_t *needrightsp,
               struct file **fpp, seq_t *seqp);
   
   /* Requires a FILEDESC_{S,X}LOCK held and returns without a ref. */
   static __inline struct file *
   fget_locked(struct filedesc *fdp, int fd)
   {
   
           FILEDESC_LOCK_ASSERT(fdp);
   
           if (fd < 0 || fd > fdp->fd_lastfile)
                   return (NULL);
   
           return (fdp->fd_ofiles[fd].fde_file);
   }
   
   static __inline struct filedescent *
   fdeget_locked(struct filedesc *fdp, int fd)
   {
           struct filedescent *fde;
   
           FILEDESC_LOCK_ASSERT(fdp);
   
           if (fd < 0 || fd > fdp->fd_lastfile)
                   return (NULL);
   
           fde = &fdp->fd_ofiles[fd];
           if (fde->fde_file == NULL)
                   return (NULL);
   
           return (fde);
   }
   
   #ifdef CAPABILITIES
   static __inline bool
   fd_modified(struct filedesc *fdp, int fd, seq_t seq)
   {
   
           return (!seq_consistent(fd_seq(fdp->fd_files, fd), seq));
   }
   #endif
   
   /* cdir/rdir/jdir manipulation functions. */
   void    pwd_chdir(struct thread *td, struct vnode *vp);
   int     pwd_chroot(struct thread *td, struct vnode *vp);
   int     pwd_chroot_chdir(struct thread *td, struct vnode *vp);
   void    pwd_ensure_dirs(void);
   
   #endif /* _KERNEL */
   
   #endif /* !_SYS_FILEDESC_H_ */

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