| // Copyright 2009 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 implements access to PE (Microsoft Windows Portable Executable) files. |
| package pe |
| |
| import ( |
| "bytes" |
| "compress/zlib" |
| "debug/dwarf" |
| "encoding/binary" |
| "fmt" |
| "io" |
| "os" |
| "strings" |
| ) |
| |
| // Avoid use of post-Go 1.4 io features, to make safe for toolchain bootstrap. |
| const seekStart = 0 |
| |
| // A File represents an open PE file. |
| type File struct { |
| FileHeader |
| OptionalHeader interface{} // of type *OptionalHeader32 or *OptionalHeader64 |
| Sections []*Section |
| Symbols []*Symbol // COFF symbols with auxiliary symbol records removed |
| COFFSymbols []COFFSymbol // all COFF symbols (including auxiliary symbol records) |
| StringTable StringTable |
| |
| closer io.Closer |
| } |
| |
| // Open opens the named file using os.Open and prepares it for use as a PE binary. |
| func Open(name string) (*File, error) { |
| f, err := os.Open(name) |
| if err != nil { |
| return nil, err |
| } |
| ff, err := NewFile(f) |
| if err != nil { |
| f.Close() |
| return nil, err |
| } |
| ff.closer = f |
| return ff, nil |
| } |
| |
| // Close closes the File. |
| // If the File was created using NewFile directly instead of Open, |
| // Close has no effect. |
| func (f *File) Close() error { |
| var err error |
| if f.closer != nil { |
| err = f.closer.Close() |
| f.closer = nil |
| } |
| return err |
| } |
| |
| // TODO(brainman): add Load function, as a replacement for NewFile, that does not call removeAuxSymbols (for performance) |
| |
| // NewFile creates a new File for accessing a PE binary in an underlying reader. |
| func NewFile(r io.ReaderAt) (*File, error) { |
| f := new(File) |
| sr := io.NewSectionReader(r, 0, 1<<63-1) |
| |
| var dosheader [96]byte |
| if _, err := r.ReadAt(dosheader[0:], 0); err != nil { |
| return nil, err |
| } |
| var base int64 |
| if dosheader[0] == 'M' && dosheader[1] == 'Z' { |
| signoff := int64(binary.LittleEndian.Uint32(dosheader[0x3c:])) |
| var sign [4]byte |
| r.ReadAt(sign[:], signoff) |
| if !(sign[0] == 'P' && sign[1] == 'E' && sign[2] == 0 && sign[3] == 0) { |
| return nil, fmt.Errorf("Invalid PE COFF file signature of %v.", sign) |
| } |
| base = signoff + 4 |
| } else { |
| base = int64(0) |
| } |
| sr.Seek(base, seekStart) |
| if err := binary.Read(sr, binary.LittleEndian, &f.FileHeader); err != nil { |
| return nil, err |
| } |
| switch f.FileHeader.Machine { |
| case IMAGE_FILE_MACHINE_UNKNOWN, IMAGE_FILE_MACHINE_ARMNT, IMAGE_FILE_MACHINE_AMD64, IMAGE_FILE_MACHINE_I386: |
| default: |
| return nil, fmt.Errorf("Unrecognised COFF file header machine value of 0x%x.", f.FileHeader.Machine) |
| } |
| |
| var err error |
| |
| // Read string table. |
| f.StringTable, err = readStringTable(&f.FileHeader, sr) |
| if err != nil { |
| return nil, err |
| } |
| |
| // Read symbol table. |
| f.COFFSymbols, err = readCOFFSymbols(&f.FileHeader, sr) |
| if err != nil { |
| return nil, err |
| } |
| f.Symbols, err = removeAuxSymbols(f.COFFSymbols, f.StringTable) |
| if err != nil { |
| return nil, err |
| } |
| |
| // Seek past file header. |
| _, err = sr.Seek(base+int64(binary.Size(f.FileHeader)), seekStart) |
| if err != nil { |
| return nil, fmt.Errorf("failure to seek past the file header: %v", err) |
| } |
| |
| // Read optional header. |
| f.OptionalHeader, err = readOptionalHeader(sr, f.FileHeader.SizeOfOptionalHeader) |
| if err != nil { |
| return nil, err |
| } |
| |
| // Process sections. |
| f.Sections = make([]*Section, f.FileHeader.NumberOfSections) |
| for i := 0; i < int(f.FileHeader.NumberOfSections); i++ { |
| sh := new(SectionHeader32) |
| if err := binary.Read(sr, binary.LittleEndian, sh); err != nil { |
| return nil, err |
| } |
| name, err := sh.fullName(f.StringTable) |
| if err != nil { |
| return nil, err |
| } |
| s := new(Section) |
| s.SectionHeader = SectionHeader{ |
| Name: name, |
| VirtualSize: sh.VirtualSize, |
| VirtualAddress: sh.VirtualAddress, |
| Size: sh.SizeOfRawData, |
| Offset: sh.PointerToRawData, |
| PointerToRelocations: sh.PointerToRelocations, |
| PointerToLineNumbers: sh.PointerToLineNumbers, |
| NumberOfRelocations: sh.NumberOfRelocations, |
| NumberOfLineNumbers: sh.NumberOfLineNumbers, |
| Characteristics: sh.Characteristics, |
| } |
| r2 := r |
| if sh.PointerToRawData == 0 { // .bss must have all 0s |
| r2 = zeroReaderAt{} |
| } |
| s.sr = io.NewSectionReader(r2, int64(s.SectionHeader.Offset), int64(s.SectionHeader.Size)) |
| s.ReaderAt = s.sr |
| f.Sections[i] = s |
| } |
| for i := range f.Sections { |
| var err error |
| f.Sections[i].Relocs, err = readRelocs(&f.Sections[i].SectionHeader, sr) |
| if err != nil { |
| return nil, err |
| } |
| } |
| |
| return f, nil |
| } |
| |
| // zeroReaderAt is ReaderAt that reads 0s. |
| type zeroReaderAt struct{} |
| |
| // ReadAt writes len(p) 0s into p. |
| func (w zeroReaderAt) ReadAt(p []byte, off int64) (n int, err error) { |
| for i := range p { |
| p[i] = 0 |
| } |
| return len(p), nil |
| } |
| |
| // getString extracts a string from symbol string table. |
| func getString(section []byte, start int) (string, bool) { |
| if start < 0 || start >= len(section) { |
| return "", false |
| } |
| |
| for end := start; end < len(section); end++ { |
| if section[end] == 0 { |
| return string(section[start:end]), true |
| } |
| } |
| return "", false |
| } |
| |
| // Section returns the first section with the given name, or nil if no such |
| // section exists. |
| func (f *File) Section(name string) *Section { |
| for _, s := range f.Sections { |
| if s.Name == name { |
| return s |
| } |
| } |
| return nil |
| } |
| |
| func (f *File) DWARF() (*dwarf.Data, error) { |
| dwarfSuffix := func(s *Section) string { |
| switch { |
| case strings.HasPrefix(s.Name, ".debug_"): |
| return s.Name[7:] |
| case strings.HasPrefix(s.Name, ".zdebug_"): |
| return s.Name[8:] |
| default: |
| return "" |
| } |
| |
| } |
| |
| // sectionData gets the data for s and checks its size. |
| sectionData := func(s *Section) ([]byte, error) { |
| b, err := s.Data() |
| if err != nil && uint32(len(b)) < s.Size { |
| return nil, err |
| } |
| |
| if 0 < s.VirtualSize && s.VirtualSize < s.Size { |
| b = b[:s.VirtualSize] |
| } |
| |
| if len(b) >= 12 && string(b[:4]) == "ZLIB" { |
| dlen := binary.BigEndian.Uint64(b[4:12]) |
| dbuf := make([]byte, dlen) |
| r, err := zlib.NewReader(bytes.NewBuffer(b[12:])) |
| if err != nil { |
| return nil, err |
| } |
| if _, err := io.ReadFull(r, dbuf); err != nil { |
| return nil, err |
| } |
| if err := r.Close(); err != nil { |
| return nil, err |
| } |
| b = dbuf |
| } |
| return b, nil |
| } |
| |
| // There are many other DWARF sections, but these |
| // are the ones the debug/dwarf package uses. |
| // Don't bother loading others. |
| var dat = map[string][]byte{"abbrev": nil, "info": nil, "str": nil, "line": nil, "ranges": nil} |
| for _, s := range f.Sections { |
| suffix := dwarfSuffix(s) |
| if suffix == "" { |
| continue |
| } |
| if _, ok := dat[suffix]; !ok { |
| continue |
| } |
| |
| b, err := sectionData(s) |
| if err != nil { |
| return nil, err |
| } |
| dat[suffix] = b |
| } |
| |
| d, err := dwarf.New(dat["abbrev"], nil, nil, dat["info"], dat["line"], nil, dat["ranges"], dat["str"]) |
| if err != nil { |
| return nil, err |
| } |
| |
| // Look for DWARF4 .debug_types sections. |
| for i, s := range f.Sections { |
| suffix := dwarfSuffix(s) |
| if suffix != "types" { |
| continue |
| } |
| |
| b, err := sectionData(s) |
| if err != nil { |
| return nil, err |
| } |
| |
| err = d.AddTypes(fmt.Sprintf("types-%d", i), b) |
| if err != nil { |
| return nil, err |
| } |
| } |
| |
| return d, nil |
| } |
| |
| // TODO(brainman): document ImportDirectory once we decide what to do with it. |
| |
| type ImportDirectory struct { |
| OriginalFirstThunk uint32 |
| TimeDateStamp uint32 |
| ForwarderChain uint32 |
| Name uint32 |
| FirstThunk uint32 |
| |
| dll string |
| } |
| |
| // ImportedSymbols returns the names of all symbols |
| // referred to by the binary f that are expected to be |
| // satisfied by other libraries at dynamic load time. |
| // It does not return weak symbols. |
| func (f *File) ImportedSymbols() ([]string, error) { |
| if f.OptionalHeader == nil { |
| return nil, nil |
| } |
| |
| pe64 := f.Machine == IMAGE_FILE_MACHINE_AMD64 |
| |
| // grab the number of data directory entries |
| var dd_length uint32 |
| if pe64 { |
| dd_length = f.OptionalHeader.(*OptionalHeader64).NumberOfRvaAndSizes |
| } else { |
| dd_length = f.OptionalHeader.(*OptionalHeader32).NumberOfRvaAndSizes |
| } |
| |
| // check that the length of data directory entries is large |
| // enough to include the imports directory. |
| if dd_length < IMAGE_DIRECTORY_ENTRY_IMPORT+1 { |
| return nil, nil |
| } |
| |
| // grab the import data directory entry |
| var idd DataDirectory |
| if pe64 { |
| idd = f.OptionalHeader.(*OptionalHeader64).DataDirectory[IMAGE_DIRECTORY_ENTRY_IMPORT] |
| } else { |
| idd = f.OptionalHeader.(*OptionalHeader32).DataDirectory[IMAGE_DIRECTORY_ENTRY_IMPORT] |
| } |
| |
| // figure out which section contains the import directory table |
| var ds *Section |
| ds = nil |
| for _, s := range f.Sections { |
| if s.VirtualAddress <= idd.VirtualAddress && idd.VirtualAddress < s.VirtualAddress+s.VirtualSize { |
| ds = s |
| break |
| } |
| } |
| |
| // didn't find a section, so no import libraries were found |
| if ds == nil { |
| return nil, nil |
| } |
| |
| d, err := ds.Data() |
| if err != nil { |
| return nil, err |
| } |
| |
| // seek to the virtual address specified in the import data directory |
| d = d[idd.VirtualAddress-ds.VirtualAddress:] |
| |
| // start decoding the import directory |
| var ida []ImportDirectory |
| for len(d) >= 20 { |
| var dt ImportDirectory |
| dt.OriginalFirstThunk = binary.LittleEndian.Uint32(d[0:4]) |
| dt.TimeDateStamp = binary.LittleEndian.Uint32(d[4:8]) |
| dt.ForwarderChain = binary.LittleEndian.Uint32(d[8:12]) |
| dt.Name = binary.LittleEndian.Uint32(d[12:16]) |
| dt.FirstThunk = binary.LittleEndian.Uint32(d[16:20]) |
| d = d[20:] |
| if dt.OriginalFirstThunk == 0 { |
| break |
| } |
| ida = append(ida, dt) |
| } |
| // TODO(brainman): this needs to be rewritten |
| // ds.Data() returns contents of section containing import table. Why store in variable called "names"? |
| // Why we are retrieving it second time? We already have it in "d", and it is not modified anywhere. |
| // getString does not extracts a string from symbol string table (as getString doco says). |
| // Why ds.Data() called again and again in the loop? |
| // Needs test before rewrite. |
| names, _ := ds.Data() |
| var all []string |
| for _, dt := range ida { |
| dt.dll, _ = getString(names, int(dt.Name-ds.VirtualAddress)) |
| d, _ = ds.Data() |
| // seek to OriginalFirstThunk |
| d = d[dt.OriginalFirstThunk-ds.VirtualAddress:] |
| for len(d) > 0 { |
| if pe64 { // 64bit |
| va := binary.LittleEndian.Uint64(d[0:8]) |
| d = d[8:] |
| if va == 0 { |
| break |
| } |
| if va&0x8000000000000000 > 0 { // is Ordinal |
| // TODO add dynimport ordinal support. |
| } else { |
| fn, _ := getString(names, int(uint32(va)-ds.VirtualAddress+2)) |
| all = append(all, fn+":"+dt.dll) |
| } |
| } else { // 32bit |
| va := binary.LittleEndian.Uint32(d[0:4]) |
| d = d[4:] |
| if va == 0 { |
| break |
| } |
| if va&0x80000000 > 0 { // is Ordinal |
| // TODO add dynimport ordinal support. |
| //ord := va&0x0000FFFF |
| } else { |
| fn, _ := getString(names, int(va-ds.VirtualAddress+2)) |
| all = append(all, fn+":"+dt.dll) |
| } |
| } |
| } |
| } |
| |
| return all, nil |
| } |
| |
| // ImportedLibraries returns the names of all libraries |
| // referred to by the binary f that are expected to be |
| // linked with the binary at dynamic link time. |
| func (f *File) ImportedLibraries() ([]string, error) { |
| // TODO |
| // cgo -dynimport don't use this for windows PE, so just return. |
| return nil, nil |
| } |
| |
| // FormatError is unused. |
| // The type is retained for compatibility. |
| type FormatError struct { |
| } |
| |
| func (e *FormatError) Error() string { |
| return "unknown error" |
| } |
| |
| // readOptionalHeader accepts a io.ReadSeeker pointing to optional header in the PE file |
| // and its size as seen in the file header. |
| // It parses the given size of bytes and returns optional header. It infers whether the |
| // bytes being parsed refer to 32 bit or 64 bit version of optional header. |
| func readOptionalHeader(r io.ReadSeeker, sz uint16) (interface{}, error) { |
| // If optional header size is 0, return empty optional header. |
| if sz == 0 { |
| return nil, nil |
| } |
| |
| var ( |
| // First couple of bytes in option header state its type. |
| // We need to read them first to determine the type and |
| // validity of optional header. |
| ohMagic uint16 |
| ohMagicSz = binary.Size(ohMagic) |
| ) |
| |
| // If optional header size is greater than 0 but less than its magic size, return error. |
| if sz < uint16(ohMagicSz) { |
| return nil, fmt.Errorf("optional header size is less than optional header magic size") |
| } |
| |
| // read reads from io.ReadSeeke, r, into data. |
| var err error |
| read := func(data interface{}) bool { |
| err = binary.Read(r, binary.LittleEndian, data) |
| return err == nil |
| } |
| |
| if !read(&ohMagic) { |
| return nil, fmt.Errorf("failure to read optional header magic: %v", err) |
| |
| } |
| |
| switch ohMagic { |
| case 0x10b: // PE32 |
| var ( |
| oh32 OptionalHeader32 |
| // There can be 0 or more data directories. So the minimum size of optional |
| // header is calculated by substracting oh32.DataDirectory size from oh32 size. |
| oh32MinSz = binary.Size(oh32) - binary.Size(oh32.DataDirectory) |
| ) |
| |
| if sz < uint16(oh32MinSz) { |
| return nil, fmt.Errorf("optional header size(%d) is less minimum size (%d) of PE32 optional header", sz, oh32MinSz) |
| } |
| |
| // Init oh32 fields |
| oh32.Magic = ohMagic |
| if !read(&oh32.MajorLinkerVersion) || |
| !read(&oh32.MinorLinkerVersion) || |
| !read(&oh32.SizeOfCode) || |
| !read(&oh32.SizeOfInitializedData) || |
| !read(&oh32.SizeOfUninitializedData) || |
| !read(&oh32.AddressOfEntryPoint) || |
| !read(&oh32.BaseOfCode) || |
| !read(&oh32.BaseOfData) || |
| !read(&oh32.ImageBase) || |
| !read(&oh32.SectionAlignment) || |
| !read(&oh32.FileAlignment) || |
| !read(&oh32.MajorOperatingSystemVersion) || |
| !read(&oh32.MinorOperatingSystemVersion) || |
| !read(&oh32.MajorImageVersion) || |
| !read(&oh32.MinorImageVersion) || |
| !read(&oh32.MajorSubsystemVersion) || |
| !read(&oh32.MinorSubsystemVersion) || |
| !read(&oh32.Win32VersionValue) || |
| !read(&oh32.SizeOfImage) || |
| !read(&oh32.SizeOfHeaders) || |
| !read(&oh32.CheckSum) || |
| !read(&oh32.Subsystem) || |
| !read(&oh32.DllCharacteristics) || |
| !read(&oh32.SizeOfStackReserve) || |
| !read(&oh32.SizeOfStackCommit) || |
| !read(&oh32.SizeOfHeapReserve) || |
| !read(&oh32.SizeOfHeapCommit) || |
| !read(&oh32.LoaderFlags) || |
| !read(&oh32.NumberOfRvaAndSizes) { |
| return nil, fmt.Errorf("failure to read PE32 optional header: %v", err) |
| } |
| |
| dd, err := readDataDirectories(r, sz-uint16(oh32MinSz), oh32.NumberOfRvaAndSizes) |
| if err != nil { |
| return nil, err |
| } |
| |
| copy(oh32.DataDirectory[:], dd) |
| |
| return &oh32, nil |
| case 0x20b: // PE32+ |
| var ( |
| oh64 OptionalHeader64 |
| // There can be 0 or more data directories. So the minimum size of optional |
| // header is calculated by substracting oh64.DataDirectory size from oh64 size. |
| oh64MinSz = binary.Size(oh64) - binary.Size(oh64.DataDirectory) |
| ) |
| |
| if sz < uint16(oh64MinSz) { |
| return nil, fmt.Errorf("optional header size(%d) is less minimum size (%d) for PE32+ optional header", sz, oh64MinSz) |
| } |
| |
| // Init oh64 fields |
| oh64.Magic = ohMagic |
| if !read(&oh64.MajorLinkerVersion) || |
| !read(&oh64.MinorLinkerVersion) || |
| !read(&oh64.SizeOfCode) || |
| !read(&oh64.SizeOfInitializedData) || |
| !read(&oh64.SizeOfUninitializedData) || |
| !read(&oh64.AddressOfEntryPoint) || |
| !read(&oh64.BaseOfCode) || |
| !read(&oh64.ImageBase) || |
| !read(&oh64.SectionAlignment) || |
| !read(&oh64.FileAlignment) || |
| !read(&oh64.MajorOperatingSystemVersion) || |
| !read(&oh64.MinorOperatingSystemVersion) || |
| !read(&oh64.MajorImageVersion) || |
| !read(&oh64.MinorImageVersion) || |
| !read(&oh64.MajorSubsystemVersion) || |
| !read(&oh64.MinorSubsystemVersion) || |
| !read(&oh64.Win32VersionValue) || |
| !read(&oh64.SizeOfImage) || |
| !read(&oh64.SizeOfHeaders) || |
| !read(&oh64.CheckSum) || |
| !read(&oh64.Subsystem) || |
| !read(&oh64.DllCharacteristics) || |
| !read(&oh64.SizeOfStackReserve) || |
| !read(&oh64.SizeOfStackCommit) || |
| !read(&oh64.SizeOfHeapReserve) || |
| !read(&oh64.SizeOfHeapCommit) || |
| !read(&oh64.LoaderFlags) || |
| !read(&oh64.NumberOfRvaAndSizes) { |
| return nil, fmt.Errorf("failure to read PE32+ optional header: %v", err) |
| } |
| |
| dd, err := readDataDirectories(r, sz-uint16(oh64MinSz), oh64.NumberOfRvaAndSizes) |
| if err != nil { |
| return nil, err |
| } |
| |
| copy(oh64.DataDirectory[:], dd) |
| |
| return &oh64, nil |
| default: |
| return nil, fmt.Errorf("optional header has unexpected Magic of 0x%x", ohMagic) |
| } |
| } |
| |
| // readDataDirectories accepts a io.ReadSeeker pointing to data directories in the PE file, |
| // its size and number of data directories as seen in optional header. |
| // It parses the given size of bytes and returns given number of data directories. |
| func readDataDirectories(r io.ReadSeeker, sz uint16, n uint32) ([]DataDirectory, error) { |
| ddSz := binary.Size(DataDirectory{}) |
| if uint32(sz) != n*uint32(ddSz) { |
| return nil, fmt.Errorf("size of data directories(%d) is inconsistent with number of data directories(%d)", sz, n) |
| } |
| |
| dd := make([]DataDirectory, n) |
| if err := binary.Read(r, binary.LittleEndian, dd); err != nil { |
| return nil, fmt.Errorf("failure to read data directories: %v", err) |
| } |
| |
| return dd, nil |
| } |
