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// Copyright 2016 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package pe
import (
"encoding/binary"
"fmt"
"internal/saferio"
"io"
"strconv"
)
// SectionHeader32 represents real PE COFF section header.
type SectionHeader32 struct {
Name [8]uint8
VirtualSize uint32
VirtualAddress uint32
SizeOfRawData uint32
PointerToRawData uint32
PointerToRelocations uint32
PointerToLineNumbers uint32
NumberOfRelocations uint16
NumberOfLineNumbers uint16
Characteristics uint32
}
// fullName finds real name of section sh. Normally name is stored
// in sh.Name, but if it is longer then 8 characters, it is stored
// in COFF string table st instead.
func (sh *SectionHeader32) fullName(st StringTable) (string, error) {
if sh.Name[0] != '/' {
return cstring(sh.Name[:]), nil
}
i, err := strconv.Atoi(cstring(sh.Name[1:]))
if err != nil {
return "", err
}
return st.String(uint32(i))
}
// TODO(brainman): copy all IMAGE_REL_* consts from ldpe.go here
// Reloc represents a PE COFF relocation.
// Each section contains its own relocation list.
type Reloc struct {
VirtualAddress uint32
SymbolTableIndex uint32
Type uint16
}
func readRelocs(sh *SectionHeader, r io.ReadSeeker) ([]Reloc, error) {
if sh.NumberOfRelocations <= 0 {
return nil, nil
}
_, err := r.Seek(int64(sh.PointerToRelocations), io.SeekStart)
if err != nil {
return nil, fmt.Errorf("fail to seek to %q section relocations: %v", sh.Name, err)
}
relocs := make([]Reloc, sh.NumberOfRelocations)
err = binary.Read(r, binary.LittleEndian, relocs)
if err != nil {
return nil, fmt.Errorf("fail to read section relocations: %v", err)
}
return relocs, nil
}
// SectionHeader is similar to SectionHeader32 with Name
// field replaced by Go string.
type SectionHeader struct {
Name string
VirtualSize uint32
VirtualAddress uint32
Size uint32
Offset uint32
PointerToRelocations uint32
PointerToLineNumbers uint32
NumberOfRelocations uint16
NumberOfLineNumbers uint16
Characteristics uint32
}
// Section provides access to PE COFF section.
type Section struct {
SectionHeader
Relocs []Reloc
// Embed ReaderAt for ReadAt method.
// Do not embed SectionReader directly
// to avoid having Read and Seek.
// If a client wants Read and Seek it must use
// Open() to avoid fighting over the seek offset
// with other clients.
io.ReaderAt
sr *io.SectionReader
}
// Data reads and returns the contents of the PE section s.
//
// If s.Offset is 0, the section has no contents,
// and Data will always return a non-nil error.
func (s *Section) Data() ([]byte, error) {
return saferio.ReadDataAt(s.sr, uint64(s.Size), 0)
}
// Open returns a new ReadSeeker reading the PE section s.
//
// If s.Offset is 0, the section has no contents, and all calls
// to the returned reader will return a non-nil error.
func (s *Section) Open() io.ReadSeeker {
return io.NewSectionReader(s.sr, 0, 1<<63-1)
}
// Section characteristics flags.
const (
IMAGE_SCN_CNT_CODE = 0x00000020
IMAGE_SCN_CNT_INITIALIZED_DATA = 0x00000040
IMAGE_SCN_CNT_UNINITIALIZED_DATA = 0x00000080
IMAGE_SCN_LNK_COMDAT = 0x00001000
IMAGE_SCN_MEM_DISCARDABLE = 0x02000000
IMAGE_SCN_MEM_EXECUTE = 0x20000000
IMAGE_SCN_MEM_READ = 0x40000000
IMAGE_SCN_MEM_WRITE = 0x80000000
)
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