kern_syscalls.c

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    1 /*-
    2  * Copyright (c) 1999 Assar Westerlund
    3  * 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  *
   14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   24  * SUCH DAMAGE.
   25  *
   26  * $FreeBSD: src/sys/kern/kern_syscalls.c,v 1.6 1999/10/11 15:19:10 peter Exp $
   27  * $DragonFly: src/sys/kern/kern_syscalls.c,v 1.4 2006/06/05 07:26:10 dillon Exp $
   28  */
   29 
   30 #include <sys/param.h>
   31 #include <sys/sysproto.h>
   32 #include <sys/sysent.h>
   33 #include <sys/syscall.h>
   34 #include <sys/module.h>
   35 
   36 /*
   37  * Acts like "nosys" but can be identified in sysent for dynamic call 
   38  * number assignment for a limited number of calls. 
   39  * 
   40  * Place holder for system call slots reserved for loadable modules.
   41  */     
   42 int
   43 sys_lkmnosys(struct nosys_args *args)
   44 {
   45         return(sys_nosys(args));
   46 }
   47 
   48 int
   49 syscall_register(int *offset, struct sysent *new_sysent,
   50                  struct sysent *old_sysent)
   51 {
   52        if (*offset == NO_SYSCALL) {
   53                int i;
   54 
   55                for (i = 1; i < SYS_MAXSYSCALL; ++i)
   56                        if (sysent[i].sy_call == (sy_call_t *)sys_lkmnosys)
   57                                break;
   58                if (i == SYS_MAXSYSCALL)
   59                        return ENFILE;
   60                *offset = i;
   61        } else if (*offset < 0 || *offset >= SYS_MAXSYSCALL)
   62                return EINVAL;
   63        else if (sysent[*offset].sy_call != (sy_call_t *)sys_lkmnosys)
   64                return EEXIST;
   65 
   66        *old_sysent = sysent[*offset];
   67        sysent[*offset] = *new_sysent;
   68        return 0;
   69 }
   70 
   71 int
   72 syscall_deregister(int *offset, struct sysent *old_sysent)
   73 {
   74        if (*offset)
   75                sysent[*offset] = *old_sysent;
   76        return 0;
   77 }
   78 
   79 int
   80 syscall_module_handler(struct module *mod, int what, void *arg)
   81 {
   82        struct syscall_module_data *data = (struct syscall_module_data*)arg;
   83        modspecific_t ms;
   84        int error;
   85 
   86        switch (what) {
   87        case MOD_LOAD :
   88                error = syscall_register(data->offset, data->new_sysent,
   89                                         &data->old_sysent);
   90                if (error)
   91                        return error;
   92                ms.intval = *data->offset;
   93                module_setspecific(mod, &ms);
   94                if (data->chainevh)
   95                        error = data->chainevh(mod, what, data->chainarg);
   96                return error;
   97 
   98        case MOD_UNLOAD :
   99                if (data->chainevh) {
  100                        error = data->chainevh(mod, what, data->chainarg);
  101                        if (error)
  102                                return error;
  103                }
  104                error = syscall_deregister(data->offset, &data->old_sysent);
  105                return error;
  106        }
  107 
  108        if (data->chainevh)
  109                return data->chainevh(mod, what, data->chainarg);
  110        else
  111                return 0;
  112 }

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FreeBSD/Linux Kernel Cross Reference sys/kern/kern_syscalls.c

FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_syscalls.c