1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
|
.\" $OpenBSD: sysctl_int.9,v 1.1 2006/01/18 14:51:43 mickey Exp $
.\"
.\" Copyright (c) 2006 Michael Shalayeff
.\" All rights reserved.
.\"
.\" Permission to use, copy, modify, and distribute this software for any
.\" purpose with or without fee is hereby granted, provided that the above
.\" copyright notice and this permission notice appear in all copies.
.\"
.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
.\"
.Dd January 20, 2006
.Dt SYSCTL_INT 9
.Os
.Sh NAME
.Nm sysctl_int ,
.Nm sysctl_int_arr ,
.Nm sysctl_quad ,
.Nm sysctl_string ,
.Nm sysctl_tstring ,
.Nm sysctl_rdint ,
.Nm sysctl_rdquad ,
.Nm sysctl_rdstring ,
.Nm sysctl_rdstruct ,
.Nm sysctl_struct
.Nd kernel sysctl interface
.Sh SYNOPSIS
.Fd #include <sys/types.h>
.Fd #include <sys/sysctl.h>
.Ft int
.Fn sysctl_int "void *oldp" "size_t *oldlenp" "void *newp" "size_t newlen" "int *valp"
.Ft int
.Fn sysctl_int_arr "int **valpp" "int *name" "u_int namelen" "void *oldp" "size_t *oldlenp" "void *newp" "size_t newlen"
.Ft int
.Fn sysctl_quad "void *oldp" "size_t *oldlenp" "void *newp" "size_t newlen" "int64_t *valp"
.Ft int
.Fn sysctl_string "void *oldp" "size_t *oldlenp" "void *newp" "size_t newlen" "char *str" "int maxlen"
.Ft int
.Fn sysctl_tstring "void *oldp" "size_t *oldlenp" "void *newp" "size_t newlen" "char *str" "int maxlen"
.Ft int
.Fn sysctl_rdint "void *oldp" "size_t *oldlenp" "void *newp" "int val"
.Ft int
.Fn sysctl_rdquad "void *oldp" "size_t *oldlenp" "void *newp" "int64_t val"
.Ft int
.Fn sysctl_rdstring "void *oldp" "size_t *oldlenp" "void *newp" "const char *str"
.Ft int
.Fn sysctl_rdstruct "void *oldp" "size_t *oldlenp" "void *newp" "const void *sp" "int len"
.Ft int
.Fn sysctl_struct "void *oldp" "size_t *oldlenp" "void *newp" "size_t newlen" "void *sp" "int len"
.Sh DESCRIPTION
These functions and data structures are aimed to simplify and partially
implement oprations for kernel and user implementation of sysctl interface.
Single
.Xr syscall 9
is used to request and modify kernel variables.
The
.Nm mib
argument is recursively scanned as an array of integers either calling
futher function for parsing the rest of the MIB for nodes or operating
on kernel data for leaf nodes.
.Ss Data Structures
For each level of MIB tree kernel header files provide a
.Nm cpp 1
macro initialiser for an array of the following data structures:
.Bd -literal -offset indent
struct ctlname {
char *ctl_name; /* subsystem name */
int ctl_type; /* type of name */
};
.Ed
.Pp
For example:
.Bd -literal -offset indent
#define CTL_NAMES { \\
{ 0, 0 }, \\
{ "kern", CTLTYPE_NODE }, \\
{ "vm", CTLTYPE_NODE }, \\
{ "fs", CTLTYPE_NODE }, \\
{ "net", CTLTYPE_NODE }, \\
{ "debug", CTLTYPE_NODE }, \\
{ "hw", CTLTYPE_NODE }, \\
{ "machdep", CTLTYPE_NODE }, \\
{ "user", CTLTYPE_NODE }, \\
{ "ddb", CTLTYPE_NODE }, \\
{ "vfs", CTLTYPE_NODE }, \\
}
.Ed
.Pp
Each array element initialiser maps the correspondent MIB identifier.
The
.Nm ctl_name
field provides a string name.
The
.Nm ctl_type
field describes the identifier type where possible values are:
.Bl -tag -width CTLTYPE_STRING_ -compact -offset indent
.It CTLTYPE_NODE
The name is a node;
.It CTLTYPE_INT
The name describes an integer;
.It CTLTYPE_STRING
The name describes a string;
.It CTLTYPE_QUAD
The name describes a 64-bit number;
.It CTLTYPE_STRUCT
The name describes a structure.
.El
For each of the types there are two functions provided to perform both
read and write or only a read operations on the identifier (see the
following subsection).
.Pp
These data structures are used by the
.Xr sysctl 8
program to provide mapping into MIB identifiers.
.Ss Functions
All of the functions perform a write shall
.Ar newp
argument be not
.Nm NULL
pointer and
.Ar newlen
be specifies appropriate data length.
All read-only versions of the functions return
.Nm EPERM
shall a write operation be requested.
.Pp
The following helper functions are provided to aid operating on the
kernel data variables referenced by the leaf nodes in the MIBs:
.Bl -tag -width sysctl_
.It Fn sysctl_int "void *oldp" "size_t *oldlenp" "void *newp" "size_t newlen" "int *valp"
The variable referenced by the
.Ar valp
is a 32-bit integer.
Read or write returning previous value in the user memory location
pointed by the
.Ar oldp
argument.
The value pointed to by the
.Ar oldlenp
has to be no less then four.
.It Fn sysctl_rdint "void *oldp" "size_t *oldlenp" "void *newp" "int val"
A read-only version of the above.
.\" .It sysctl_int_arr
.It Fn sysctl_quad "void *oldp" "size_t *oldlenp" "void *newp" "size_t newlen" "int64_t *valp"
The variable referenced is a 64-bit integer.
Read or write returning previous value in the user memory location
pointed by the
.Ar oldp
argument.
The value pointed to by the
.Ar oldlenp
has to be no less then eight.
.It Fn sysctl_rdquad "void *oldp" "size_t *oldlenp" "void *newp" "int64_t val"
A read-only version of the above.
.It Fn sysctl_string "void *oldp" "size_t *oldlenp" "void *newp" "size_t newlen" "char *str" "int maxlen"
The variable referenced by the
.Ar str
argument is a string of maximum length of
.Ar maxlen .
Copy out old value into user buffer pointed to by the
.Ar oldp
argument.
If there is not enough space to store that a
.Nm ENOMEM
is returned.
If
.Ar newlen
larger than
.Ar maxlen
a
.Nm EINVAL
error is returned.
.It Fn sysctl_tstring "void *oldp" "size_t *oldlenp" "void *newp" "size_t newlen" "char *str" "int maxlen"
A version of the above that truncates the old value that does not fit
into the buffer provided byt
.Ar oldp
instead of returning
.Nm ENOMEM .
.It Fn sysctl_rdstring "void *oldp" "size_t *oldlenp" "void *newp" "const char *str"
A read-only version of the
.Nm sysctl_string .
.It Fn sysctl_struct "void *oldp" "size_t *oldlenp" "void *newp" "size_t newlen" "void *sp" "int len"
Aassume the area pointed to by the
.Ar sp
argument be an opaque array of byte of size
.Ar len .
Old and new length checks are performed and data is copied in and/or out.
.It Fn sysctl_rdstruct "void *oldp" "size_t *oldlenp" "void *newp" "const void *sp" "int len"
A read-only version of the above.
.El
.Sh SEE ALSO
.Xr sysctl 3 ,
.Xr sysctl.conf 5 ,
.Xr sysctl 8 ,
.Xr syscall 9
.Sh HISTORY
These functions first appeared in
.Bx 4.4 .
.\" .Sh AUTHORS
|
