Nathan Baulch
65 lines
1.6 KiB
Go
65 lines
1.6 KiB
Go
// Package danger provides optimized unsafe functions.
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package danger
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import (
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"fmt"
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"unsafe"
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)
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const maxInt = uintptr(int(^uint(0) >> 1))
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func SubsliceOffset(data []byte, subslice []byte) int {
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datap := uintptr(unsafe.Pointer(unsafe.SliceData(data))) // #nosec G103
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hlp := uintptr(unsafe.Pointer(unsafe.SliceData(subslice))) // #nosec G103
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if hlp < datap {
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panic(fmt.Errorf("subslice address (%d) is before data address (%d)", hlp, datap))
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}
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offset := hlp - datap
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if offset > maxInt {
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panic(fmt.Errorf("slice offset larger than int (%d)", offset))
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}
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intoffset := int(offset)
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if intoffset > len(data) {
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panic(fmt.Errorf("slice offset (%d) is farther than data length (%d)", intoffset, len(data)))
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}
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if intoffset+len(subslice) > len(data) {
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panic(fmt.Errorf("slice ends (%d+%d) is farther than data length (%d)", intoffset, len(subslice), len(data)))
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}
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return intoffset
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}
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func BytesRange(start []byte, end []byte) []byte {
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if start == nil || end == nil {
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panic("cannot call BytesRange with nil")
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}
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startp := uintptr(unsafe.Pointer(unsafe.SliceData(start))) // #nosec G103
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endp := uintptr(unsafe.Pointer(unsafe.SliceData(end))) // #nosec G103
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if startp > endp {
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panic(fmt.Errorf("start pointer address (%d) is after end pointer address (%d)", startp, endp))
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}
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l := len(start)
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endLen := int(endp-startp) + len(end)
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if endLen > l {
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l = endLen
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}
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if l > cap(start) {
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panic("range length is larger than capacity")
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}
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return start[:l]
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}
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func Stride(ptr unsafe.Pointer, size uintptr, offset int) unsafe.Pointer {
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return unsafe.Add(ptr, size*uintptr(offset))
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}
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