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

     /*-
      * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
      *
      * Copyright (c) 2009 Robert N. M. Watson
      * All rights reserved.
      *
      * This software was developed at the University of Cambridge Computer
      * Laboratory with support from a grant from Google, Inc.
      *
     * 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.
     *
     * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
     *
     * $FreeBSD: releng/12.0/sys/sys/procdesc.h 326256 2017-11-27 15:01:59Z pfg $
     */
    
    #ifndef _SYS_PROCDESC_H_
    #define _SYS_PROCDESC_H_
    
    #ifdef _KERNEL
    
    #include <sys/selinfo.h>        /* struct selinfo */
    #include <sys/_lock.h>
    #include <sys/_mutex.h>
    
    /*-
     * struct procdesc describes a process descriptor, and essentially consists
     * of two pointers -- one to the file descriptor, and one to the process.
     * When both become NULL, the process descriptor will be freed.  An important
     * invariant is that there is only ever one process descriptor for a process,
     * so a single file pointer will suffice.
     *
     * Locking key:
     * (c) - Constant after initial setup.
     * (p) - Protected by the process descriptor mutex.
     * (r) - Atomic reference count.
     * (s) - Protected by selinfo.
     * (t) - Protected by the proctree_lock
     */
    struct proc;
    struct sigio;
    struct procdesc {
            /*
             * Basic process descriptor state: the process, a cache of its pid to
             * satisfy queries after the process exits, and process descriptor
             * refcount.
             */
            struct proc     *pd_proc;               /* (t) Process. */
            pid_t            pd_pid;                /* (c) Cached pid. */
            u_int            pd_refcount;           /* (r) Reference count. */
    
            /*
             * In-flight data and notification of events.
             */
            int              pd_flags;              /* (p) PD_ flags. */
            u_short          pd_xstat;              /* (p) Exit status. */
            struct selinfo   pd_selinfo;            /* (p) Event notification. */
            struct mtx       pd_lock;               /* Protect data + events. */
    };
    
    /*
     * Locking macros for the procdesc itself.
     */
    #define PROCDESC_LOCK_DESTROY(pd)       mtx_destroy(&(pd)->pd_lock)
    #define PROCDESC_LOCK_INIT(pd)  mtx_init(&(pd)->pd_lock, "procdesc", NULL, \
                                        MTX_DEF)
    #define PROCDESC_LOCK(pd)       mtx_lock(&(pd)->pd_lock)
    #define PROCDESC_UNLOCK(pd)     mtx_unlock(&(pd)->pd_lock)
    
    /*
     * Flags for the pd_flags field.
     */
    #define PDF_CLOSED      0x00000001      /* Descriptor has closed. */
    #define PDF_SELECTED    0x00000002      /* Issue selwakeup(). */
    #define PDF_EXITED      0x00000004      /* Process exited. */
    #define PDF_DAEMON      0x00000008      /* Don't exit when procdesc closes. */
    
    /*
     * In-kernel interfaces to process descriptors.
     */
    int      procdesc_exit(struct proc *);
    int      procdesc_find(struct thread *, int fd, cap_rights_t *, struct proc **);
   int      kern_pdgetpid(struct thread *, int fd, cap_rights_t *, pid_t *pidp);
   void     procdesc_new(struct proc *, int);
   void     procdesc_finit(struct procdesc *, struct file *);
   pid_t    procdesc_pid(struct file *);
   void     procdesc_reap(struct proc *);
   
   int      procdesc_falloc(struct thread *, struct file **, int *, int,
               struct filecaps *);
   
   #else /* !_KERNEL */
   
   #include <sys/_types.h>
   
   #ifndef _PID_T_DECLARED
   typedef __pid_t         pid_t;
   #define _PID_T_DECLARED
   #endif
   
   struct rusage;
   
   /*
    * Process descriptor system calls.
    */
   __BEGIN_DECLS
   pid_t    pdfork(int *, int);
   int      pdkill(int, int);
   int      pdgetpid(int, pid_t *);
   __END_DECLS
   
   #endif /* _KERNEL */
   
   /*
    * Flags which can be passed to pdfork(2).
    */
   #define PD_DAEMON       0x00000001      /* Don't exit when procdesc closes. */
   #define PD_CLOEXEC      0x00000002      /* Close file descriptor on exec. */
   
   #define PD_ALLOWED_AT_FORK      (PD_DAEMON | PD_CLOEXEC)
   
   #endif /* !_SYS_PROCDESC_H_ */

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