sys/kern/kern_syscalls.c

   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 09:26:10 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 }