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/11.1/sys/sys/filedesc.h 315895 2017-03-24 08:06:00Z mjg $
   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 struct fdescenttbl {
   66         int     fdt_nfiles;             /* number of open files allocated */
   67         struct  filedescent fdt_ofiles[0];      /* open files */
   68 };
   69 #define fd_seq(fdt, fd) (&(fdt)->fdt_ofiles[(fd)].fde_seq)
   70 
   71 /*
   72  * This structure is used for the management of descriptors.  It may be
   73  * shared by multiple processes.
   74  */
   75 #define NDSLOTTYPE      u_long
   76 
   77 struct filedesc {
   78         struct  fdescenttbl *fd_files;  /* open files table */
   79         struct  vnode *fd_cdir;         /* current directory */
   80         struct  vnode *fd_rdir;         /* root directory */
   81         struct  vnode *fd_jdir;         /* jail root directory */
   82         NDSLOTTYPE *fd_map;             /* bitmap of free fds */
   83         int     fd_lastfile;            /* high-water mark of fd_ofiles */
   84         int     fd_freefile;            /* approx. next free file */
   85         u_short fd_cmask;               /* mask for file creation */
   86         int     fd_refcnt;              /* thread reference count */
   87         int     fd_holdcnt;             /* hold count on structure + mutex */
   88         struct  sx fd_sx;               /* protects members of this struct */
   89         struct  kqlist fd_kqlist;       /* list of kqueues on this filedesc */
   90         int     fd_holdleaderscount;    /* block fdfree() for shared close() */
   91         int     fd_holdleaderswakeup;   /* fdfree() needs wakeup */
   92 };
   93 
   94 /*
   95  * Structure to keep track of (process leader, struct fildedesc) tuples.
   96  * Each process has a pointer to such a structure when detailed tracking
   97  * is needed, e.g., when rfork(RFPROC | RFMEM) causes a file descriptor
   98  * table to be shared by processes having different "p_leader" pointers
   99  * and thus distinct POSIX style locks.
  100  *
  101  * fdl_refcount and fdl_holdcount are protected by struct filedesc mtx.
  102  */
  103 struct filedesc_to_leader {
  104         int             fdl_refcount;   /* references from struct proc */
  105         int             fdl_holdcount;  /* temporary hold during closef */
  106         int             fdl_wakeup;     /* fdfree() waits on closef() */
  107         struct proc     *fdl_leader;    /* owner of POSIX locks */
  108         /* Circular list: */
  109         struct filedesc_to_leader *fdl_prev;
  110         struct filedesc_to_leader *fdl_next;
  111 };
  112 #define fd_nfiles       fd_files->fdt_nfiles
  113 #define fd_ofiles       fd_files->fdt_ofiles
  114 
  115 /*
  116  * Per-process open flags.
  117  */
  118 #define UF_EXCLOSE      0x01            /* auto-close on exec */
  119 
  120 #ifdef _KERNEL
  121 
  122 /* Lock a file descriptor table. */
  123 #define FILEDESC_LOCK_INIT(fdp) sx_init(&(fdp)->fd_sx, "filedesc structure")
  124 #define FILEDESC_LOCK_DESTROY(fdp)      sx_destroy(&(fdp)->fd_sx)
  125 #define FILEDESC_LOCK(fdp)      (&(fdp)->fd_sx)
  126 #define FILEDESC_XLOCK(fdp)     sx_xlock(&(fdp)->fd_sx)
  127 #define FILEDESC_XUNLOCK(fdp)   sx_xunlock(&(fdp)->fd_sx)
  128 #define FILEDESC_SLOCK(fdp)     sx_slock(&(fdp)->fd_sx)
  129 #define FILEDESC_SUNLOCK(fdp)   sx_sunlock(&(fdp)->fd_sx)
  130 
  131 #define FILEDESC_LOCK_ASSERT(fdp)       sx_assert(&(fdp)->fd_sx, SX_LOCKED | \
  132                                             SX_NOTRECURSED)
  133 #define FILEDESC_XLOCK_ASSERT(fdp)      sx_assert(&(fdp)->fd_sx, SX_XLOCKED | \
  134                                             SX_NOTRECURSED)
  135 #define FILEDESC_UNLOCK_ASSERT(fdp)     sx_assert(&(fdp)->fd_sx, SX_UNLOCKED)
  136 
  137 /* Operation types for kern_dup(). */
  138 enum {
  139         FDDUP_NORMAL,           /* dup() behavior. */
  140         FDDUP_FCNTL,            /* fcntl()-style errors. */
  141         FDDUP_FIXED,            /* Force fixed allocation. */
  142         FDDUP_MUSTREPLACE,      /* Target must exist. */
  143         FDDUP_LASTMODE,
  144 };
  145 
  146 /* Flags for kern_dup(). */
  147 #define FDDUP_FLAG_CLOEXEC      0x1     /* Atomically set UF_EXCLOSE. */
  148 
  149 /* For backward compatibility. */
  150 #define falloc(td, resultfp, resultfd, flags) \
  151         falloc_caps(td, resultfp, resultfd, flags, NULL)
  152 
  153 struct thread;
  154 
  155 void    filecaps_init(struct filecaps *fcaps);
  156 int     filecaps_copy(const struct filecaps *src, struct filecaps *dst,
  157             bool locked);
  158 void    filecaps_move(struct filecaps *src, struct filecaps *dst);
  159 void    filecaps_free(struct filecaps *fcaps);
  160 
  161 int     closef(struct file *fp, struct thread *td);
  162 int     dupfdopen(struct thread *td, struct filedesc *fdp, int dfd, int mode,
  163             int openerror, int *indxp);
  164 int     falloc_caps(struct thread *td, struct file **resultfp, int *resultfd,
  165             int flags, struct filecaps *fcaps);
  166 int     falloc_noinstall(struct thread *td, struct file **resultfp);
  167 void    _finstall(struct filedesc *fdp, struct file *fp, int fd, int flags,
  168             struct filecaps *fcaps);
  169 int     finstall(struct thread *td, struct file *fp, int *resultfd, int flags,
  170             struct filecaps *fcaps);
  171 int     fdalloc(struct thread *td, int minfd, int *result);
  172 int     fdallocn(struct thread *td, int minfd, int *fds, int n);
  173 int     fdcheckstd(struct thread *td);
  174 void    fdclose(struct thread *td, struct file *fp, int idx);
  175 void    fdcloseexec(struct thread *td);
  176 void    fdsetugidsafety(struct thread *td);
  177 struct  filedesc *fdcopy(struct filedesc *fdp);
  178 int     fdcopy_remapped(struct filedesc *fdp, const int *fds, size_t nfds,
  179             struct filedesc **newfdp);
  180 void    fdinstall_remapped(struct thread *td, struct filedesc *fdp);
  181 void    fdunshare(struct thread *td);
  182 void    fdescfree(struct thread *td);
  183 void    fdescfree_remapped(struct filedesc *fdp);
  184 struct  filedesc *fdinit(struct filedesc *fdp, bool prepfiles);
  185 struct  filedesc *fdshare(struct filedesc *fdp);
  186 struct filedesc_to_leader *
  187         filedesc_to_leader_alloc(struct filedesc_to_leader *old,
  188             struct filedesc *fdp, struct proc *leader);
  189 int     getvnode(struct thread *td, int fd, cap_rights_t *rightsp,
  190             struct file **fpp);
  191 void    mountcheckdirs(struct vnode *olddp, struct vnode *newdp);
  192 
  193 int     fget_cap_locked(struct filedesc *fdp, int fd, cap_rights_t *needrightsp,
  194             struct file **fpp, struct filecaps *havecapsp);
  195 int     fget_cap(struct thread *td, int fd, cap_rights_t *needrightsp,
  196             struct file **fpp, struct filecaps *havecapsp);
  197 
  198 /* Return a referenced file from an unlocked descriptor. */
  199 int     fget_unlocked(struct filedesc *fdp, int fd, cap_rights_t *needrightsp,
  200             struct file **fpp, seq_t *seqp);
  201 
  202 /* Requires a FILEDESC_{S,X}LOCK held and returns without a ref. */
  203 static __inline struct file *
  204 fget_locked(struct filedesc *fdp, int fd)
  205 {
  206 
  207         FILEDESC_LOCK_ASSERT(fdp);
  208 
  209         if (fd < 0 || fd > fdp->fd_lastfile)
  210                 return (NULL);
  211 
  212         return (fdp->fd_ofiles[fd].fde_file);
  213 }
  214 
  215 static __inline struct filedescent *
  216 fdeget_locked(struct filedesc *fdp, int fd)
  217 {
  218         struct filedescent *fde;
  219 
  220         FILEDESC_LOCK_ASSERT(fdp);
  221 
  222         if ((u_int)fd > fdp->fd_lastfile)
  223                 return (NULL);
  224 
  225         fde = &fdp->fd_ofiles[fd];
  226         if (fde->fde_file == NULL)
  227                 return (NULL);
  228 
  229         return (fde);
  230 }
  231 
  232 static __inline bool
  233 fd_modified(struct filedesc *fdp, int fd, seq_t seq)
  234 {
  235 
  236         return (!seq_consistent(fd_seq(fdp->fd_files, fd), seq));
  237 }
  238 
  239 /* cdir/rdir/jdir manipulation functions. */
  240 void    pwd_chdir(struct thread *td, struct vnode *vp);
  241 int     pwd_chroot(struct thread *td, struct vnode *vp);
  242 void    pwd_ensure_dirs(void);
  243 
  244 #endif /* _KERNEL */
  245 
  246 #endif /* !_SYS_FILEDESC_H_ */

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