// Copyright 2016 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package pe
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import (
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"encoding/binary"
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"fmt"
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"io"
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)
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const COFFSymbolSize = 18
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// COFFSymbol represents single COFF symbol table record.
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type COFFSymbol struct {
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Name [8]uint8
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Value uint32
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SectionNumber int16
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Type uint16
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StorageClass uint8
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NumberOfAuxSymbols uint8
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}
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func readCOFFSymbols(fh *FileHeader, r io.ReadSeeker) ([]COFFSymbol, error) {
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if fh.PointerToSymbolTable == 0 {
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return nil, nil
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}
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if fh.NumberOfSymbols <= 0 {
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return nil, nil
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}
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_, err := r.Seek(int64(fh.PointerToSymbolTable), seekStart)
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if err != nil {
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return nil, fmt.Errorf("fail to seek to symbol table: %v", err)
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}
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syms := make([]COFFSymbol, fh.NumberOfSymbols)
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err = binary.Read(r, binary.LittleEndian, syms)
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if err != nil {
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return nil, fmt.Errorf("fail to read symbol table: %v", err)
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}
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return syms, nil
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}
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// isSymNameOffset checks symbol name if it is encoded as offset into string table.
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func isSymNameOffset(name [8]byte) (bool, uint32) {
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if name[0] == 0 && name[1] == 0 && name[2] == 0 && name[3] == 0 {
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return true, binary.LittleEndian.Uint32(name[4:])
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}
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return false, 0
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}
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// FullName finds real name of symbol sym. Normally name is stored
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// in sym.Name, but if it is longer then 8 characters, it is stored
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// in COFF string table st instead.
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func (sym *COFFSymbol) FullName(st StringTable) (string, error) {
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if ok, offset := isSymNameOffset(sym.Name); ok {
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return st.String(offset)
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}
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return cstring(sym.Name[:]), nil
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}
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func removeAuxSymbols(allsyms []COFFSymbol, st StringTable) ([]*Symbol, error) {
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if len(allsyms) == 0 {
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return nil, nil
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}
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syms := make([]*Symbol, 0)
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aux := uint8(0)
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for _, sym := range allsyms {
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if aux > 0 {
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aux--
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continue
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}
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name, err := sym.FullName(st)
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if err != nil {
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return nil, err
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}
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aux = sym.NumberOfAuxSymbols
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s := &Symbol{
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Name: name,
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Value: sym.Value,
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SectionNumber: sym.SectionNumber,
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Type: sym.Type,
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StorageClass: sym.StorageClass,
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}
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syms = append(syms, s)
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}
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return syms, nil
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}
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// Symbol is similar to COFFSymbol with Name field replaced
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// by Go string. Symbol also does not have NumberOfAuxSymbols.
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type Symbol struct {
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Name string
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Value uint32
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SectionNumber int16
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Type uint16
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StorageClass uint8
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}
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