From 82bcbebce43f0227f506d75a5b764b6847041bae Mon Sep 17 00:00:00 2001 From: Ben Cheng Date: Mon, 1 Oct 2012 10:30:31 -0700 Subject: Initial check-in of gcc 4.7.2. Change-Id: I4a2f5a921c21741a0e18bda986d77e5f1bef0365 --- gcc-4.7/libgo/go/debug/elf/file.go | 762 +++++++++++++++++++++++++++++++++++++ 1 file changed, 762 insertions(+) create mode 100644 gcc-4.7/libgo/go/debug/elf/file.go (limited to 'gcc-4.7/libgo/go/debug/elf/file.go') diff --git a/gcc-4.7/libgo/go/debug/elf/file.go b/gcc-4.7/libgo/go/debug/elf/file.go new file mode 100644 index 000000000..31895f192 --- /dev/null +++ b/gcc-4.7/libgo/go/debug/elf/file.go @@ -0,0 +1,762 @@ +// 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 elf implements access to ELF object files. +package elf + +import ( + "bytes" + "debug/dwarf" + "encoding/binary" + "errors" + "fmt" + "io" + "os" +) + +// TODO: error reporting detail + +/* + * Internal ELF representation + */ + +// A FileHeader represents an ELF file header. +type FileHeader struct { + Class Class + Data Data + Version Version + OSABI OSABI + ABIVersion uint8 + ByteOrder binary.ByteOrder + Type Type + Machine Machine +} + +// A File represents an open ELF file. +type File struct { + FileHeader + Sections []*Section + Progs []*Prog + closer io.Closer + gnuNeed []verneed + gnuVersym []byte +} + +// A SectionHeader represents a single ELF section header. +type SectionHeader struct { + Name string + Type SectionType + Flags SectionFlag + Addr uint64 + Offset uint64 + Size uint64 + Link uint32 + Info uint32 + Addralign uint64 + Entsize uint64 +} + +// A Section represents a single section in an ELF file. +type Section struct { + SectionHeader + + // 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 ELF section. +func (s *Section) Data() ([]byte, error) { + dat := make([]byte, s.sr.Size()) + n, err := s.sr.ReadAt(dat, 0) + return dat[0:n], err +} + +// stringTable reads and returns the string table given by the +// specified link value. +func (f *File) stringTable(link uint32) ([]byte, error) { + if link <= 0 || link >= uint32(len(f.Sections)) { + return nil, errors.New("section has invalid string table link") + } + return f.Sections[link].Data() +} + +// Open returns a new ReadSeeker reading the ELF section. +func (s *Section) Open() io.ReadSeeker { return io.NewSectionReader(s.sr, 0, 1<<63-1) } + +// A ProgHeader represents a single ELF program header. +type ProgHeader struct { + Type ProgType + Flags ProgFlag + Off uint64 + Vaddr uint64 + Paddr uint64 + Filesz uint64 + Memsz uint64 + Align uint64 +} + +// A Prog represents a single ELF program header in an ELF binary. +type Prog struct { + ProgHeader + + // 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 +} + +// Open returns a new ReadSeeker reading the ELF program body. +func (p *Prog) Open() io.ReadSeeker { return io.NewSectionReader(p.sr, 0, 1<<63-1) } + +// A Symbol represents an entry in an ELF symbol table section. +type Symbol struct { + Name string + Info, Other byte + Section SectionIndex + Value, Size uint64 +} + +/* + * ELF reader + */ + +type FormatError struct { + off int64 + msg string + val interface{} +} + +func (e *FormatError) Error() string { + msg := e.msg + if e.val != nil { + msg += fmt.Sprintf(" '%v' ", e.val) + } + msg += fmt.Sprintf("in record at byte %#x", e.off) + return msg +} + +// Open opens the named file using os.Open and prepares it for use as an ELF 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 +} + +// SectionByType returns the first section in f with the +// given type, or nil if there is no such section. +func (f *File) SectionByType(typ SectionType) *Section { + for _, s := range f.Sections { + if s.Type == typ { + return s + } + } + return nil +} + +// NewFile creates a new File for accessing an ELF binary in an underlying reader. +// The ELF binary is expected to start at position 0 in the ReaderAt. +func NewFile(r io.ReaderAt) (*File, error) { + sr := io.NewSectionReader(r, 0, 1<<63-1) + // Read and decode ELF identifier + var ident [16]uint8 + if _, err := r.ReadAt(ident[0:], 0); err != nil { + return nil, err + } + if ident[0] != '\x7f' || ident[1] != 'E' || ident[2] != 'L' || ident[3] != 'F' { + return nil, &FormatError{0, "bad magic number", ident[0:4]} + } + + f := new(File) + f.Class = Class(ident[EI_CLASS]) + switch f.Class { + case ELFCLASS32: + case ELFCLASS64: + // ok + default: + return nil, &FormatError{0, "unknown ELF class", f.Class} + } + + f.Data = Data(ident[EI_DATA]) + switch f.Data { + case ELFDATA2LSB: + f.ByteOrder = binary.LittleEndian + case ELFDATA2MSB: + f.ByteOrder = binary.BigEndian + default: + return nil, &FormatError{0, "unknown ELF data encoding", f.Data} + } + + f.Version = Version(ident[EI_VERSION]) + if f.Version != EV_CURRENT { + return nil, &FormatError{0, "unknown ELF version", f.Version} + } + + f.OSABI = OSABI(ident[EI_OSABI]) + f.ABIVersion = ident[EI_ABIVERSION] + + // Read ELF file header + var phoff int64 + var phentsize, phnum int + var shoff int64 + var shentsize, shnum, shstrndx int + shstrndx = -1 + switch f.Class { + case ELFCLASS32: + hdr := new(Header32) + sr.Seek(0, os.SEEK_SET) + if err := binary.Read(sr, f.ByteOrder, hdr); err != nil { + return nil, err + } + f.Type = Type(hdr.Type) + f.Machine = Machine(hdr.Machine) + if v := Version(hdr.Version); v != f.Version { + return nil, &FormatError{0, "mismatched ELF version", v} + } + phoff = int64(hdr.Phoff) + phentsize = int(hdr.Phentsize) + phnum = int(hdr.Phnum) + shoff = int64(hdr.Shoff) + shentsize = int(hdr.Shentsize) + shnum = int(hdr.Shnum) + shstrndx = int(hdr.Shstrndx) + case ELFCLASS64: + hdr := new(Header64) + sr.Seek(0, os.SEEK_SET) + if err := binary.Read(sr, f.ByteOrder, hdr); err != nil { + return nil, err + } + f.Type = Type(hdr.Type) + f.Machine = Machine(hdr.Machine) + if v := Version(hdr.Version); v != f.Version { + return nil, &FormatError{0, "mismatched ELF version", v} + } + phoff = int64(hdr.Phoff) + phentsize = int(hdr.Phentsize) + phnum = int(hdr.Phnum) + shoff = int64(hdr.Shoff) + shentsize = int(hdr.Shentsize) + shnum = int(hdr.Shnum) + shstrndx = int(hdr.Shstrndx) + } + if shstrndx < 0 || shstrndx >= shnum { + return nil, &FormatError{0, "invalid ELF shstrndx", shstrndx} + } + + // Read program headers + f.Progs = make([]*Prog, phnum) + for i := 0; i < phnum; i++ { + off := phoff + int64(i)*int64(phentsize) + sr.Seek(off, os.SEEK_SET) + p := new(Prog) + switch f.Class { + case ELFCLASS32: + ph := new(Prog32) + if err := binary.Read(sr, f.ByteOrder, ph); err != nil { + return nil, err + } + p.ProgHeader = ProgHeader{ + Type: ProgType(ph.Type), + Flags: ProgFlag(ph.Flags), + Off: uint64(ph.Off), + Vaddr: uint64(ph.Vaddr), + Paddr: uint64(ph.Paddr), + Filesz: uint64(ph.Filesz), + Memsz: uint64(ph.Memsz), + Align: uint64(ph.Align), + } + case ELFCLASS64: + ph := new(Prog64) + if err := binary.Read(sr, f.ByteOrder, ph); err != nil { + return nil, err + } + p.ProgHeader = ProgHeader{ + Type: ProgType(ph.Type), + Flags: ProgFlag(ph.Flags), + Off: uint64(ph.Off), + Vaddr: uint64(ph.Vaddr), + Paddr: uint64(ph.Paddr), + Filesz: uint64(ph.Filesz), + Memsz: uint64(ph.Memsz), + Align: uint64(ph.Align), + } + } + p.sr = io.NewSectionReader(r, int64(p.Off), int64(p.Filesz)) + p.ReaderAt = p.sr + f.Progs[i] = p + } + + // Read section headers + f.Sections = make([]*Section, shnum) + names := make([]uint32, shnum) + for i := 0; i < shnum; i++ { + off := shoff + int64(i)*int64(shentsize) + sr.Seek(off, os.SEEK_SET) + s := new(Section) + switch f.Class { + case ELFCLASS32: + sh := new(Section32) + if err := binary.Read(sr, f.ByteOrder, sh); err != nil { + return nil, err + } + names[i] = sh.Name + s.SectionHeader = SectionHeader{ + Type: SectionType(sh.Type), + Flags: SectionFlag(sh.Flags), + Addr: uint64(sh.Addr), + Offset: uint64(sh.Off), + Size: uint64(sh.Size), + Link: uint32(sh.Link), + Info: uint32(sh.Info), + Addralign: uint64(sh.Addralign), + Entsize: uint64(sh.Entsize), + } + case ELFCLASS64: + sh := new(Section64) + if err := binary.Read(sr, f.ByteOrder, sh); err != nil { + return nil, err + } + names[i] = sh.Name + s.SectionHeader = SectionHeader{ + Type: SectionType(sh.Type), + Flags: SectionFlag(sh.Flags), + Offset: uint64(sh.Off), + Size: uint64(sh.Size), + Addr: uint64(sh.Addr), + Link: uint32(sh.Link), + Info: uint32(sh.Info), + Addralign: uint64(sh.Addralign), + Entsize: uint64(sh.Entsize), + } + } + s.sr = io.NewSectionReader(r, int64(s.Offset), int64(s.Size)) + s.ReaderAt = s.sr + f.Sections[i] = s + } + + // Load section header string table. + shstrtab, err := f.Sections[shstrndx].Data() + if err != nil { + return nil, err + } + for i, s := range f.Sections { + var ok bool + s.Name, ok = getString(shstrtab, int(names[i])) + if !ok { + return nil, &FormatError{shoff + int64(i*shentsize), "bad section name index", names[i]} + } + } + + return f, nil +} + +// getSymbols returns a slice of Symbols from parsing the symbol table +// with the given type, along with the associated string table. +func (f *File) getSymbols(typ SectionType) ([]Symbol, []byte, error) { + switch f.Class { + case ELFCLASS64: + return f.getSymbols64(typ) + + case ELFCLASS32: + return f.getSymbols32(typ) + } + + return nil, nil, errors.New("not implemented") +} + +func (f *File) getSymbols32(typ SectionType) ([]Symbol, []byte, error) { + symtabSection := f.SectionByType(typ) + if symtabSection == nil { + return nil, nil, errors.New("no symbol section") + } + + data, err := symtabSection.Data() + if err != nil { + return nil, nil, errors.New("cannot load symbol section") + } + symtab := bytes.NewBuffer(data) + if symtab.Len()%Sym32Size != 0 { + return nil, nil, errors.New("length of symbol section is not a multiple of SymSize") + } + + strdata, err := f.stringTable(symtabSection.Link) + if err != nil { + return nil, nil, errors.New("cannot load string table section") + } + + // The first entry is all zeros. + var skip [Sym32Size]byte + symtab.Read(skip[0:]) + + symbols := make([]Symbol, symtab.Len()/Sym32Size) + + i := 0 + var sym Sym32 + for symtab.Len() > 0 { + binary.Read(symtab, f.ByteOrder, &sym) + str, _ := getString(strdata, int(sym.Name)) + symbols[i].Name = str + symbols[i].Info = sym.Info + symbols[i].Other = sym.Other + symbols[i].Section = SectionIndex(sym.Shndx) + symbols[i].Value = uint64(sym.Value) + symbols[i].Size = uint64(sym.Size) + i++ + } + + return symbols, strdata, nil +} + +func (f *File) getSymbols64(typ SectionType) ([]Symbol, []byte, error) { + symtabSection := f.SectionByType(typ) + if symtabSection == nil { + return nil, nil, errors.New("no symbol section") + } + + data, err := symtabSection.Data() + if err != nil { + return nil, nil, errors.New("cannot load symbol section") + } + symtab := bytes.NewBuffer(data) + if symtab.Len()%Sym64Size != 0 { + return nil, nil, errors.New("length of symbol section is not a multiple of Sym64Size") + } + + strdata, err := f.stringTable(symtabSection.Link) + if err != nil { + return nil, nil, errors.New("cannot load string table section") + } + + // The first entry is all zeros. + var skip [Sym64Size]byte + symtab.Read(skip[0:]) + + symbols := make([]Symbol, symtab.Len()/Sym64Size) + + i := 0 + var sym Sym64 + for symtab.Len() > 0 { + binary.Read(symtab, f.ByteOrder, &sym) + str, _ := getString(strdata, int(sym.Name)) + symbols[i].Name = str + symbols[i].Info = sym.Info + symbols[i].Other = sym.Other + symbols[i].Section = SectionIndex(sym.Shndx) + symbols[i].Value = sym.Value + symbols[i].Size = sym.Size + i++ + } + + return symbols, strdata, nil +} + +// getString extracts a string from an ELF 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 a 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 +} + +// applyRelocations applies relocations to dst. rels is a relocations section +// in RELA format. +func (f *File) applyRelocations(dst []byte, rels []byte) error { + if f.Class == ELFCLASS64 && f.Machine == EM_X86_64 { + return f.applyRelocationsAMD64(dst, rels) + } + + return errors.New("not implemented") +} + +func (f *File) applyRelocationsAMD64(dst []byte, rels []byte) error { + if len(rels)%Sym64Size != 0 { + return errors.New("length of relocation section is not a multiple of Sym64Size") + } + + symbols, _, err := f.getSymbols(SHT_SYMTAB) + if err != nil { + return err + } + + b := bytes.NewBuffer(rels) + var rela Rela64 + + for b.Len() > 0 { + binary.Read(b, f.ByteOrder, &rela) + symNo := rela.Info >> 32 + t := R_X86_64(rela.Info & 0xffff) + + if symNo >= uint64(len(symbols)) { + continue + } + sym := &symbols[symNo] + if SymType(sym.Info&0xf) != STT_SECTION { + // We don't handle non-section relocations for now. + continue + } + + switch t { + case R_X86_64_64: + if rela.Off+8 >= uint64(len(dst)) || rela.Addend < 0 { + continue + } + f.ByteOrder.PutUint64(dst[rela.Off:rela.Off+8], uint64(rela.Addend)) + case R_X86_64_32: + if rela.Off+4 >= uint64(len(dst)) || rela.Addend < 0 { + continue + } + f.ByteOrder.PutUint32(dst[rela.Off:rela.Off+4], uint32(rela.Addend)) + } + } + + return nil +} + +func (f *File) DWARF() (*dwarf.Data, error) { + // There are many other DWARF sections, but these + // are the required ones, and the debug/dwarf package + // does not use the others, so don't bother loading them. + var names = [...]string{"abbrev", "info", "line", "ranges", "str"} + var dat [len(names)][]byte + for i, name := range names { + name = ".debug_" + name + s := f.Section(name) + if s == nil { + continue + } + b, err := s.Data() + if err != nil && uint64(len(b)) < s.Size { + return nil, err + } + dat[i] = b + } + + // If there's a relocation table for .debug_info, we have to process it + // now otherwise the data in .debug_info is invalid for x86-64 objects. + rela := f.Section(".rela.debug_info") + if rela != nil && rela.Type == SHT_RELA && f.Machine == EM_X86_64 { + data, err := rela.Data() + if err != nil { + return nil, err + } + err = f.applyRelocations(dat[1], data) + if err != nil { + return nil, err + } + } + + abbrev, info, line, ranges, str := dat[0], dat[1], dat[2], dat[3], dat[4] + return dwarf.New(abbrev, nil, nil, info, line, nil, ranges, str) +} + +// Symbols returns the symbol table for f. +func (f *File) Symbols() ([]Symbol, error) { + sym, _, err := f.getSymbols(SHT_SYMTAB) + return sym, err +} + +type ImportedSymbol struct { + Name string + Version string + Library 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() ([]ImportedSymbol, error) { + sym, str, err := f.getSymbols(SHT_DYNSYM) + if err != nil { + return nil, err + } + f.gnuVersionInit(str) + var all []ImportedSymbol + for i, s := range sym { + if ST_BIND(s.Info) == STB_GLOBAL && s.Section == SHN_UNDEF { + all = append(all, ImportedSymbol{Name: s.Name}) + f.gnuVersion(i, &all[len(all)-1]) + } + } + return all, nil +} + +type verneed struct { + File string + Name string +} + +// gnuVersionInit parses the GNU version tables +// for use by calls to gnuVersion. +func (f *File) gnuVersionInit(str []byte) { + // Accumulate verneed information. + vn := f.SectionByType(SHT_GNU_VERNEED) + if vn == nil { + return + } + d, _ := vn.Data() + + var need []verneed + i := 0 + for { + if i+16 > len(d) { + break + } + vers := f.ByteOrder.Uint16(d[i : i+2]) + if vers != 1 { + break + } + cnt := f.ByteOrder.Uint16(d[i+2 : i+4]) + fileoff := f.ByteOrder.Uint32(d[i+4 : i+8]) + aux := f.ByteOrder.Uint32(d[i+8 : i+12]) + next := f.ByteOrder.Uint32(d[i+12 : i+16]) + file, _ := getString(str, int(fileoff)) + + var name string + j := i + int(aux) + for c := 0; c < int(cnt); c++ { + if j+16 > len(d) { + break + } + // hash := f.ByteOrder.Uint32(d[j:j+4]) + // flags := f.ByteOrder.Uint16(d[j+4:j+6]) + other := f.ByteOrder.Uint16(d[j+6 : j+8]) + nameoff := f.ByteOrder.Uint32(d[j+8 : j+12]) + next := f.ByteOrder.Uint32(d[j+12 : j+16]) + name, _ = getString(str, int(nameoff)) + ndx := int(other) + if ndx >= len(need) { + a := make([]verneed, 2*(ndx+1)) + copy(a, need) + need = a + } + + need[ndx] = verneed{file, name} + if next == 0 { + break + } + j += int(next) + } + + if next == 0 { + break + } + i += int(next) + } + + // Versym parallels symbol table, indexing into verneed. + vs := f.SectionByType(SHT_GNU_VERSYM) + if vs == nil { + return + } + d, _ = vs.Data() + + f.gnuNeed = need + f.gnuVersym = d +} + +// gnuVersion adds Library and Version information to sym, +// which came from offset i of the symbol table. +func (f *File) gnuVersion(i int, sym *ImportedSymbol) { + // Each entry is two bytes; skip undef entry at beginning. + i = (i + 1) * 2 + if i >= len(f.gnuVersym) { + return + } + j := int(f.ByteOrder.Uint16(f.gnuVersym[i:])) + if j < 2 || j >= len(f.gnuNeed) { + return + } + n := &f.gnuNeed[j] + sym.Library = n.File + sym.Version = n.Name +} + +// 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) { + ds := f.SectionByType(SHT_DYNAMIC) + if ds == nil { + // not dynamic, so no libraries + return nil, nil + } + d, err := ds.Data() + if err != nil { + return nil, err + } + str, err := f.stringTable(ds.Link) + if err != nil { + return nil, err + } + var all []string + for len(d) > 0 { + var tag DynTag + var value uint64 + switch f.Class { + case ELFCLASS32: + tag = DynTag(f.ByteOrder.Uint32(d[0:4])) + value = uint64(f.ByteOrder.Uint32(d[4:8])) + d = d[8:] + case ELFCLASS64: + tag = DynTag(f.ByteOrder.Uint64(d[0:8])) + value = f.ByteOrder.Uint64(d[8:16]) + d = d[16:] + } + if tag == DT_NEEDED { + s, ok := getString(str, int(value)) + if ok { + all = append(all, s) + } + } + } + + return all, nil +} -- cgit v1.2.3