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
|
// +build !cgo
// Copyright 2018 psgo authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// Package host extracts data from the host, such as the system's boot time or
// the tick rate of the system clock.
package host
import (
"encoding/binary"
"fmt"
"io/ioutil"
"unsafe"
)
var (
// cache host queries to redundant calculations
clockTicks *int64
bootTime *int64
)
func getNativeEndianness() binary.ByteOrder {
var i int32 = 0x00000001
u := unsafe.Pointer(&i)
if *((*byte)(u)) == 0x01 {
return binary.LittleEndian
}
return binary.BigEndian
}
const (
atClktck = 17
)
func getFromAuxv(what uint, whatName string) (uint, error) {
dataLen := int(unsafe.Sizeof(int(0)))
p, err := ioutil.ReadFile("/proc/self/auxv")
if err != nil {
return 0, err
}
native := getNativeEndianness()
for i := 0; i < len(p); {
var k, v uint
switch dataLen {
case 4:
k = uint(native.Uint32(p[i : i+dataLen]))
v = uint(native.Uint32(p[i+dataLen : i+dataLen*2]))
case 8:
k = uint(native.Uint64(p[i : i+dataLen]))
v = uint(native.Uint64(p[i+dataLen : i+dataLen*2]))
}
i += dataLen * 2
if k == what {
return v, nil
}
}
return 0, fmt.Errorf("cannot find %s in auxv", whatName)
}
// ClockTicks returns sysconf(SC_CLK_TCK).
func ClockTicks() (int64, error) {
if clockTicks == nil {
ret, err := getFromAuxv(atClktck, "AT_CLKTCK")
if err != nil {
return -1, err
}
ticks := int64(ret)
clockTicks = &ticks
}
return *clockTicks, nil
}
|
