66 lines
1.6 KiB
Go
66 lines
1.6 KiB
Go
|
package danger
|
||
|
|
|
||
|
|
import (
|
||
|
|
"fmt"
|
||
|
|
"reflect"
|
||
|
|
"unsafe"
|
||
|
|
)
|
||
|
|
|
||
|
|
const maxInt = uintptr(int(^uint(0) >> 1))
|
||
|
|
|
||
|
|
func SubsliceOffset(data []byte, subslice []byte) int {
|
||
|
|
datap := (*reflect.SliceHeader)(unsafe.Pointer(&data))
|
||
|
|
hlp := (*reflect.SliceHeader)(unsafe.Pointer(&subslice))
|
||
|
|
|
||
|
|
if hlp.Data < datap.Data {
|
||
|
|
panic(fmt.Errorf("subslice address (%d) is before data address (%d)", hlp.Data, datap.Data))
|
||
|
|
}
|
||
|
|
offset := hlp.Data - datap.Data
|
||
|
|
|
||
|
|
if offset > maxInt {
|
||
|
|
panic(fmt.Errorf("slice offset larger than int (%d)", offset))
|
||
|
|
}
|
||
|
|
|
||
|
|
intoffset := int(offset)
|
||
|
|
|
||
|
|
if intoffset > datap.Len {
|
||
|
|
panic(fmt.Errorf("slice offset (%d) is farther than data length (%d)", intoffset, datap.Len))
|
||
|
|
}
|
||
|
|
|
||
|
|
if intoffset+hlp.Len > datap.Len {
|
||
|
|
panic(fmt.Errorf("slice ends (%d+%d) is farther than data length (%d)", intoffset, hlp.Len, datap.Len))
|
||
|
|
}
|
||
|
|
|
||
|
|
return intoffset
|
||
|
|
}
|
||
|
|
|
||
|
|
func BytesRange(start []byte, end []byte) []byte {
|
||
|
|
if start == nil || end == nil {
|
||
|
|
panic("cannot call BytesRange with nil")
|
||
|
|
}
|
||
|
|
startp := (*reflect.SliceHeader)(unsafe.Pointer(&start))
|
||
|
|
endp := (*reflect.SliceHeader)(unsafe.Pointer(&end))
|
||
|
|
|
||
|
|
if startp.Data > endp.Data {
|
||
|
|
panic(fmt.Errorf("start pointer address (%d) is after end pointer address (%d)", startp.Data, endp.Data))
|
||
|
|
}
|
||
|
|
|
||
|
|
l := startp.Len
|
||
|
|
endLen := int(endp.Data-startp.Data) + endp.Len
|
||
|
|
if endLen > l {
|
||
|
|
l = endLen
|
||
|
|
}
|
||
|
|
|
||
|
|
if l > startp.Cap {
|
||
|
|
panic(fmt.Errorf("range length is larger than capacity"))
|
||
|
|
}
|
||
|
|
|
||
|
|
return start[:l]
|
||
|
|
}
|
||
|
|
|
||
|
|
func Stride(ptr unsafe.Pointer, size uintptr, offset int) unsafe.Pointer {
|
||
|
|
// TODO: replace with unsafe.Add when Go 1.17 is released
|
||
|
|
// https://github.com/golang/go/issues/40481
|
||
|
|
return unsafe.Pointer(uintptr(ptr) + uintptr(int(size)*offset))
|
||
|
|
}
|