forked from elliotchance/c2go
-
Notifications
You must be signed in to change notification settings - Fork 0
/
sizeof.go
153 lines (119 loc) · 3.02 KB
/
sizeof.go
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
package types
import (
"errors"
"fmt"
"strconv"
"strings"
"github.com/elliotchance/c2go/program"
"github.com/elliotchance/c2go/util"
)
func removePrefix(s, prefix string) string {
if strings.HasPrefix(s, prefix) {
s = s[len(prefix):]
}
return s
}
// SizeOf returns the number of bytes for a type. This the same as using the
// sizeof operator/function in C.
func SizeOf(p *program.Program, cType string) (int, error) {
// Remove keywords that do not effect the size.
cType = removePrefix(cType, "signed ")
cType = removePrefix(cType, "unsigned ")
cType = removePrefix(cType, "const ")
cType = removePrefix(cType, "volatile ")
// FIXME: The pointer size will be different on different platforms. We
// should find out the correct size at runtime.
pointerSize := 8
// A structure will be the sum of its parts.
if strings.HasPrefix(cType, "struct ") {
totalBytes := 0
s := p.Structs[cType]
if s == nil {
return 0, fmt.Errorf("could not sizeof: %s", cType)
}
for _, t := range s.Fields {
var bytes int
var err error
switch f := t.(type) {
case string:
bytes, err = SizeOf(p, f)
case *program.Struct:
bytes, err = SizeOf(p, f.Name)
}
if err != nil {
return 0, err
}
totalBytes += bytes
}
// The size of a struct is rounded up to fit the size of the pointer of
// the OS.
if totalBytes%pointerSize != 0 {
totalBytes += pointerSize - (totalBytes % pointerSize)
}
return totalBytes, nil
}
// An union will be the max size of its parts.
if strings.HasPrefix(cType, "union ") {
byteCount := 0
s := p.Unions[cType]
if s == nil {
return 0, errors.New(fmt.Sprintf("could not sizeof: %s", cType))
}
for _, t := range s.Fields {
var bytes int
var err error
switch f := t.(type) {
case string:
bytes, err = SizeOf(p, f)
case *program.Struct:
bytes, err = SizeOf(p, f.Name)
}
if err != nil {
return 0, err
}
if byteCount < bytes {
byteCount = bytes
}
}
// The size of an union is rounded up to fit the size of the pointer of
// the OS.
if byteCount%pointerSize != 0 {
byteCount += pointerSize - (byteCount % pointerSize)
}
return byteCount, nil
}
// Function pointers are one byte?
if strings.Index(cType, "(") >= 0 {
return 1, nil
}
if strings.HasSuffix(cType, "*") {
return pointerSize, nil
}
switch cType {
case "char", "void":
return 1, nil
case "short":
return 2, nil
case "int", "float":
return 4, nil
case "long", "double":
return 8, nil
case "long double":
return 16, nil
}
// Get size for array types like: `base_type [count]`
groups := util.GroupsFromRegex(`^(?P<type>[^ ]+) *\[(?P<count>\d+)\]$`, cType)
if groups == nil {
return pointerSize, errors.New(
fmt.Sprintf("cannot determine size of: `%s`", cType))
}
baseSize, err := SizeOf(p, groups["type"])
if err != nil {
return 0, err
}
count, err := strconv.Atoi(groups["count"])
if err != nil {
return pointerSize, fmt.Errorf("cannot determine size of: %s", cType)
}
return baseSize * count, nil
}