mirror of https://github.com/beego/bee.git
85 lines
1.9 KiB
Go
85 lines
1.9 KiB
Go
package op
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import (
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"bytes"
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"encoding/binary"
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"errors"
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"fmt"
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"github.com/derekparker/delve/dwarf/util"
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)
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const (
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DW_OP_addr = 0x3
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DW_OP_call_frame_cfa = 0x9c
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DW_OP_plus = 0x22
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DW_OP_consts = 0x11
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DW_OP_plus_uconsts = 0x23
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)
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type stackfn func(*bytes.Buffer, []int64, int64) ([]int64, error)
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var oplut = map[byte]stackfn{
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DW_OP_call_frame_cfa: callframecfa,
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DW_OP_plus: plus,
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DW_OP_consts: consts,
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DW_OP_addr: addr,
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DW_OP_plus_uconsts: plusuconsts,
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}
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func ExecuteStackProgram(cfa int64, instructions []byte) (int64, error) {
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stack := make([]int64, 0, 3)
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buf := bytes.NewBuffer(instructions)
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for opcode, err := buf.ReadByte(); err == nil; opcode, err = buf.ReadByte() {
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fn, ok := oplut[opcode]
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if !ok {
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return 0, fmt.Errorf("invalid instruction %#v", opcode)
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}
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stack, err = fn(buf, stack, cfa)
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if err != nil {
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return 0, err
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}
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}
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if len(stack) == 0 {
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return 0, errors.New("empty OP stack")
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}
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return stack[len(stack)-1], nil
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}
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func callframecfa(buf *bytes.Buffer, stack []int64, cfa int64) ([]int64, error) {
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if cfa == 0 {
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return stack, fmt.Errorf("Could not retrieve CFA for current PC")
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}
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return append(stack, int64(cfa)), nil
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}
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func addr(buf *bytes.Buffer, stack []int64, cfa int64) ([]int64, error) {
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return append(stack, int64(binary.LittleEndian.Uint64(buf.Next(8)))), nil
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}
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func plus(buf *bytes.Buffer, stack []int64, cfa int64) ([]int64, error) {
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var (
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slen = len(stack)
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digits = stack[slen-2 : slen]
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st = stack[:slen-2]
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)
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return append(st, digits[0]+digits[1]), nil
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}
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func plusuconsts(buf *bytes.Buffer, stack []int64, cfa int64) ([]int64, error) {
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slen := len(stack)
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num, _ := util.DecodeULEB128(buf)
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stack[slen-1] = stack[slen-1] + int64(num)
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return stack, nil
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}
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func consts(buf *bytes.Buffer, stack []int64, cfa int64) ([]int64, error) {
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num, _ := util.DecodeSLEB128(buf)
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return append(stack, num), nil
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}
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