Initial import from FreeBSD RELENG_4:
[dragonfly.git] / sys / kern / kern_syscalls.c
CommitLineData
984263bc
MD
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 */
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 */
41int
42lkmnosys(struct proc *p, struct nosys_args *args)
43{
44 return(nosys(p, args));
45}
46
47int
48syscall_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
70int
71syscall_deregister(int *offset, struct sysent *old_sysent)
72{
73 if (*offset)
74 sysent[*offset] = *old_sysent;
75 return 0;
76}
77
78int
79syscall_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}