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  * $FreeBSD$
   27  */
   28 
   29 #include <sys/param.h>
   30 #include <sys/sysproto.h>
   31 #include <sys/sysent.h>
   32 #include <sys/syscall.h>
   33 #include <sys/module.h>
   34 
   35 /*
   36  * Acts like "nosys" but can be identified in sysent for dynamic call 
   37  * number assignment for a limited number of calls. 
   38  * 
   39  * Place holder for system call slots reserved for loadable modules.
   40  */     
   41 int
   42 lkmnosys(struct proc *p, struct nosys_args *args)
   43 {
   44         return(nosys(p, args));
   45 }
   46 
   47 int
   48 syscall_register(int *offset, struct sysent *new_sysent,
   49                  struct sysent *old_sysent)
   50 {
   51        if (*offset == NO_SYSCALL) {
   52                int i;
   53 
   54                for (i = 1; i < SYS_MAXSYSCALL; ++i)
   55                        if (sysent[i].sy_call == (sy_call_t *)lkmnosys)
   56                                break;
   57                if (i == SYS_MAXSYSCALL)
   58                        return ENFILE;
   59                *offset = i;
   60        } else if (*offset < 0 || *offset >= SYS_MAXSYSCALL)
   61                return EINVAL;
   62        else if (sysent[*offset].sy_call != (sy_call_t *)lkmnosys)
   63                return EEXIST;
   64 
   65        *old_sysent = sysent[*offset];
   66        sysent[*offset] = *new_sysent;
   67        return 0;
   68 }
   69 
   70 int
   71 syscall_deregister(int *offset, struct sysent *old_sysent)
   72 {
   73        if (*offset)
   74                sysent[*offset] = *old_sysent;
   75        return 0;
   76 }
   77 
   78 int
   79 syscall_module_handler(struct module *mod, int what, void *arg)
   80 {
   81        struct syscall_module_data *data = (struct syscall_module_data*)arg;
   82        modspecific_t ms;
   83        int error;
   84 
   85        switch (what) {
   86        case MOD_LOAD :
   87                error = syscall_register(data->offset, data->new_sysent,
   88                                         &data->old_sysent);
   89                if (error)
   90                        return error;
   91                ms.intval = *data->offset;
   92                module_setspecific(mod, &ms);
   93                if (data->chainevh)
   94                        error = data->chainevh(mod, what, data->chainarg);
   95                return error;
   96 
   97        case MOD_UNLOAD :
   98                if (data->chainevh) {
   99                        error = data->chainevh(mod, what, data->chainarg);
  100                        if (error)
  101                                return error;
  102                }
  103                error = syscall_deregister(data->offset, &data->old_sysent);
  104                return error;
  105        }
  106 
  107        if (data->chainevh)
  108                return data->chainevh(mod, what, data->chainarg);
  109        else
  110                return 0;
  111 }

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

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