Object: Add ELF support.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@123896 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 708 insertions, 1 deletions

diff --git a/lib/Object/CMakeLists.txt b/lib/Object/CMakeLists.txt
index 9a6451c264..6a6814fd37 100644
--- a/lib/Object/CMakeLists.txt
+++ b/lib/Object/CMakeLists.txt
@@ -2,4 +2,5 @@ add_llvm_library(LLVMObject
   MachOObject.cpp
   ObjectFile.cpp
   COFFObjectFile.cpp
+  ELFObjectFile.cpp
   )
diff --git a/lib/Object/ELFObjectFile.cpp b/lib/Object/ELFObjectFile.cpp
new file mode 100644
index 0000000000..8a232d5214
--- /dev/null
+++ b/lib/Object/ELFObjectFile.cpp
@@ -0,0 +1,706 @@
+//===- ELFObjectFile.cpp - ELF object file implementation -------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines the ELFObjectFile class.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/StringSwitch.h"
+#include "llvm/ADT/Triple.h"
+#include "llvm/Object/ObjectFile.h"
+#include "llvm/Support/ELF.h"
+#include "llvm/Support/Endian.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/MemoryBuffer.h"
+#include <limits>
+#include <utility>
+
+using namespace llvm;
+using namespace object;
+
+// Templates to choose Elf_Addr and Elf_Off depending on is64Bits.
+namespace {
+template<support::endianness target_endianness>
+struct ELFDataTypeTypedefHelperCommon {
+  typedef support::detail::packed_endian_specific_integral
+    <uint16_t, target_endianness, support::aligned> Elf_Half;
+  typedef support::detail::packed_endian_specific_integral
+    <uint32_t, target_endianness, support::aligned> Elf_Word;
+  typedef support::detail::packed_endian_specific_integral
+    <int32_t, target_endianness, support::aligned> Elf_Sword;
+  typedef support::detail::packed_endian_specific_integral
+    <uint64_t, target_endianness, support::aligned> Elf_Xword;
+  typedef support::detail::packed_endian_specific_integral
+    <int64_t, target_endianness, support::aligned> Elf_Sxword;
+};
+}
+
+namespace {
+template<support::endianness target_endianness, bool is64Bits>
+struct ELFDataTypeTypedefHelper;
+
+/// ELF 32bit types.
+template<support::endianness target_endianness>
+struct ELFDataTypeTypedefHelper<target_endianness, false>
+  : ELFDataTypeTypedefHelperCommon<target_endianness> {
+  typedef support::detail::packed_endian_specific_integral
+    <uint32_t, target_endianness, support::aligned> Elf_Addr;
+  typedef support::detail::packed_endian_specific_integral
+    <uint32_t, target_endianness, support::aligned> Elf_Off;
+};
+
+/// ELF 64bit types.
+template<support::endianness target_endianness>
+struct ELFDataTypeTypedefHelper<target_endianness, true>
+  : ELFDataTypeTypedefHelperCommon<target_endianness>{
+  typedef support::detail::packed_endian_specific_integral
+    <uint64_t, target_endianness, support::aligned> Elf_Addr;
+  typedef support::detail::packed_endian_specific_integral
+    <uint64_t, target_endianness, support::aligned> Elf_Off;
+};
+}
+
+// I really don't like doing this, but the alternative is copypasta.
+#define LLVM_ELF_IMPORT_TYPES(target_endianness, is64Bits) \
+typedef typename \
+  ELFDataTypeTypedefHelper<target_endianness, is64Bits>::Elf_Addr Elf_Addr; \
+typedef typename \
+  ELFDataTypeTypedefHelper<target_endianness, is64Bits>::Elf_Off Elf_Off; \
+typedef typename \
+  ELFDataTypeTypedefHelper<target_endianness, is64Bits>::Elf_Half Elf_Half; \
+typedef typename \
+  ELFDataTypeTypedefHelper<target_endianness, is64Bits>::Elf_Word Elf_Word; \
+typedef typename \
+  ELFDataTypeTypedefHelper<target_endianness, is64Bits>::Elf_Sword Elf_Sword; \
+typedef typename \
+  ELFDataTypeTypedefHelper<target_endianness, is64Bits>::Elf_Xword Elf_Xword; \
+typedef typename \
+  ELFDataTypeTypedefHelper<target_endianness, is64Bits>::Elf_Sxword Elf_Sxword;
+
+  // Section header.
+namespace {
+template<support::endianness target_endianness, bool is64Bits>
+struct Elf_Shdr_Base;
+
+template<support::endianness target_endianness>
+struct Elf_Shdr_Base<target_endianness, false> {
+  LLVM_ELF_IMPORT_TYPES(target_endianness, false)
+  Elf_Word sh_name;     // Section name (index into string table)
+  Elf_Word sh_type;     // Section type (SHT_*)
+  Elf_Word sh_flags;    // Section flags (SHF_*)
+  Elf_Addr sh_addr;     // Address where section is to be loaded
+  Elf_Off  sh_offset;   // File offset of section data, in bytes
+  Elf_Word sh_size;     // Size of section, in bytes
+  Elf_Word sh_link;     // Section type-specific header table index link
+  Elf_Word sh_info;     // Section type-specific extra information
+  Elf_Word sh_addralign;// Section address alignment
+  Elf_Word sh_entsize;  // Size of records contained within the section
+};
+
+template<support::endianness target_endianness>
+struct Elf_Shdr_Base<target_endianness, true> {
+  LLVM_ELF_IMPORT_TYPES(target_endianness, true)
+  Elf_Word  sh_name;     // Section name (index into string table)
+  Elf_Word  sh_type;     // Section type (SHT_*)
+  Elf_Xword sh_flags;    // Section flags (SHF_*)
+  Elf_Addr  sh_addr;     // Address where section is to be loaded
+  Elf_Off   sh_offset;   // File offset of section data, in bytes
+  Elf_Xword sh_size;     // Size of section, in bytes
+  Elf_Word  sh_link;     // Section type-specific header table index link
+  Elf_Word  sh_info;     // Section type-specific extra information
+  Elf_Xword sh_addralign;// Section address alignment
+  Elf_Xword sh_entsize;  // Size of records contained within the section
+};
+
+template<support::endianness target_endianness, bool is64Bits>
+struct Elf_Shdr_Impl : Elf_Shdr_Base<target_endianness, is64Bits> {
+  using Elf_Shdr_Base<target_endianness, is64Bits>::sh_entsize;
+  using Elf_Shdr_Base<target_endianness, is64Bits>::sh_size;
+
+  /// @brief Get the number of entities this section contains if it has any.
+  unsigned getEntityCount() const {
+    if (sh_entsize == 0)
+      return 0;
+    else
+      return sh_size / sh_entsize;
+  }
+};
+}
+
+namespace {
+template<support::endianness target_endianness, bool is64Bits>
+struct Elf_Sym_Base;
+
+template<support::endianness target_endianness>
+struct Elf_Sym_Base<target_endianness, false> {
+  LLVM_ELF_IMPORT_TYPES(target_endianness, false)
+  Elf_Word      st_name;  // Symbol name (index into string table)
+  Elf_Addr      st_value; // Value or address associated with the symbol
+  Elf_Word      st_size;  // Size of the symbol
+  unsigned char st_info;  // Symbol's type and binding attributes
+  unsigned char st_other; // Must be zero; reserved
+  Elf_Half      st_shndx; // Which section (header table index) it's defined in
+};
+
+template<support::endianness target_endianness>
+struct Elf_Sym_Base<target_endianness, true> {
+  LLVM_ELF_IMPORT_TYPES(target_endianness, true)
+  Elf_Word      st_name;  // Symbol name (index into string table)
+  unsigned char st_info;  // Symbol's type and binding attributes
+  unsigned char st_other; // Must be zero; reserved
+  Elf_Half      st_shndx; // Which section (header table index) it's defined in
+  Elf_Addr      st_value; // Value or address associated with the symbol
+  Elf_Xword     st_size;  // Size of the symbol
+};
+
+template<support::endianness target_endianness, bool is64Bits>
+struct Elf_Sym_Impl : Elf_Sym_Base<target_endianness, is64Bits> {
+  using Elf_Sym_Base<target_endianness, is64Bits>::st_info;
+
+  // These accessors and mutators correspond to the ELF32_ST_BIND,
+  // ELF32_ST_TYPE, and ELF32_ST_INFO macros defined in the ELF specification:
+  unsigned char getBinding() const { return st_info >> 4; }
+  unsigned char getType() const { return st_info & 0x0f; }
+  void setBinding(unsigned char b) { setBindingAndType(b, getType()); }
+  void setType(unsigned char t) { setBindingAndType(getBinding(), t); }
+  void setBindingAndType(unsigned char b, unsigned char t) {
+    st_info = (b << 4) + (t & 0x0f);
+  }
+};
+}
+
+namespace {
+struct ELFDataRefImpl {
+  uint32_t SymbolIndex;
+  uint16_t SymbolTableSectionIndex;
+  uint16_t Unused;
+};
+}
+
+namespace {
+template<support::endianness target_endianness, bool is64Bits>
+class ELFObjectFile : public ObjectFile {
+  LLVM_ELF_IMPORT_TYPES(target_endianness, is64Bits)
+
+  typedef Elf_Shdr_Impl<target_endianness, is64Bits> Elf_Shdr;
+  typedef Elf_Sym_Impl<target_endianness, is64Bits> Elf_Sym;
+
+  struct Elf_Ehdr {
+    unsigned char e_ident[ELF::EI_NIDENT]; // ELF Identification bytes
+    Elf_Half e_type;     // Type of file (see ET_*)
+    Elf_Half e_machine;  // Required architecture for this file (see EM_*)
+    Elf_Word e_version;  // Must be equal to 1
+    Elf_Addr e_entry;    // Address to jump to in order to start program
+    Elf_Off  e_phoff;    // Program header table's file offset, in bytes
+    Elf_Off  e_shoff;    // Section header table's file offset, in bytes
+    Elf_Word e_flags;    // Processor-specific flags
+    Elf_Half e_ehsize;   // Size of ELF header, in bytes
+    Elf_Half e_phentsize;// Size of an entry in the program header table
+    Elf_Half e_phnum;    // Number of entries in the program header table
+    Elf_Half e_shentsize;// Size of an entry in the section header table
+    Elf_Half e_shnum;    // Number of entries in the section header table
+    Elf_Half e_shstrndx; // Section header table index of section name
+                                  // string table
+    bool checkMagic() const {
+      return (memcmp(e_ident, ELF::ElfMagic, strlen(ELF::ElfMagic))) == 0;
+    }
+    unsigned char getFileClass() const { return e_ident[ELF::EI_CLASS]; }
+    unsigned char getDataEncoding() const { return e_ident[ELF::EI_DATA]; }
+  };
+
+  typedef SmallVector<const Elf_Shdr*, 1> SymbolTableSections_t;
+
+  const Elf_Ehdr *Header;
+  const Elf_Shdr *SectionHeaderTable;
+  const Elf_Shdr *dot_shstrtab_sec; // Section header string table.
+  const Elf_Shdr *dot_strtab_sec;   // Symbol header string table.
+  SymbolTableSections_t SymbolTableSections;
+
+  void            validateSymbol(DataRefImpl Symb) const;
+  const Elf_Sym  *getSymbol(DataRefImpl Symb) const;
+  const Elf_Shdr *getSection(DataRefImpl index) const;
+  const Elf_Shdr *getSection(uint16_t index) const;
+  const char     *getString(uint16_t section, uint32_t offset) const;
+  const char     *getString(const Elf_Shdr *section, uint32_t offset) const;
+
+protected:
+  virtual SymbolRef getSymbolNext(DataRefImpl Symb) const;
+  virtual StringRef getSymbolName(DataRefImpl Symb) const;
+  virtual uint64_t  getSymbolAddress(DataRefImpl Symb) const;
+  virtual uint64_t  getSymbolSize(DataRefImpl Symb) const;
+  virtual char      getSymbolNMTypeChar(DataRefImpl Symb) const;
+  virtual bool      isSymbolInternal(DataRefImpl Symb) const;
+
+  virtual SectionRef getSectionNext(DataRefImpl Sec) const;
+  virtual StringRef  getSectionName(DataRefImpl Sec) const;
+  virtual uint64_t   getSectionAddress(DataRefImpl Sec) const;
+  virtual uint64_t   getSectionSize(DataRefImpl Sec) const;
+  virtual StringRef  getSectionContents(DataRefImpl Sec) const;
+  virtual bool       isSectionText(DataRefImpl Sec) const;
+
+public:
+  ELFObjectFile(MemoryBuffer *Object);
+  virtual symbol_iterator begin_symbols() const;
+  virtual symbol_iterator end_symbols() const;
+  virtual section_iterator begin_sections() const;
+  virtual section_iterator end_sections() const;
+
+  virtual uint8_t getBytesInAddress() const;
+  virtual StringRef getFileFormatName() const;
+  virtual unsigned getArch() const;
+};
+} // end namespace
+
+template<support::endianness target_endianness, bool is64Bits>
+void ELFObjectFile<target_endianness, is64Bits>
+                  ::validateSymbol(DataRefImpl Symb) const {
+  const ELFDataRefImpl SymbolData = *reinterpret_cast<ELFDataRefImpl *>(&Symb);
+  const Elf_Sym  *symb = getSymbol(Symb);
+  const Elf_Shdr *SymbolTableSection =
+    SymbolTableSections[SymbolData.SymbolTableSectionIndex];
+  // FIXME: We really need to do proper error handling in the case of an invalid
+  //        input file. Because we don't use exceptions, I think we'll just pass
+  //        an error object around.
+  if (!(  symb
+        && SymbolTableSection
+        && symb >= (const Elf_Sym*)(base
+                   + SymbolTableSection->sh_offset)
+        && symb <  (const Elf_Sym*)(base
+                   + SymbolTableSection->sh_offset
+                   + SymbolTableSection->sh_size)))
+    // FIXME: Proper error handling.
+    report_fatal_error("Symb must point to a valid symbol!");
+}
+
+template<support::endianness target_endianness, bool is64Bits>
+SymbolRef ELFObjectFile<target_endianness, is64Bits>
+                       ::getSymbolNext(DataRefImpl Symb) const {
+  validateSymbol(Symb);
+  ELFDataRefImpl &SymbolData = *reinterpret_cast<ELFDataRefImpl *>(&Symb);
+  const Elf_Shdr *SymbolTableSection =
+    SymbolTableSections[SymbolData.SymbolTableSectionIndex];
+
+  ++SymbolData.SymbolIndex;
+  // Check to see if we are at the end of this symbol table.
+  if (SymbolData.SymbolIndex >= SymbolTableSection->getEntityCount()) {
+    // We are at the end. If there are other symbol tables, jump to them.
+    ++SymbolData.SymbolTableSectionIndex;
+    SymbolData.SymbolIndex = 1; // The 0th symbol in ELF is fake.
+    // Otherwise return the terminator.
+    if (SymbolData.SymbolTableSectionIndex >= SymbolTableSections.size()) {
+      SymbolData.SymbolIndex = std::numeric_limits<uint32_t>::max();
+      SymbolData.SymbolTableSectionIndex = std::numeric_limits<uint32_t>::max();
+    }
+  }
+
+  return SymbolRef(Symb, this);
+}
+
+template<support::endianness target_endianness, bool is64Bits>
+StringRef ELFObjectFile<target_endianness, is64Bits>
+                       ::getSymbolName(DataRefImpl Symb) const {
+  validateSymbol(Symb);
+  const Elf_Sym  *symb = getSymbol(Symb);
+  if (symb->st_name == 0) {
+    const Elf_Shdr *section = getSection(symb->st_shndx);
+    if (!section)
+      return "";
+    return getString(dot_shstrtab_sec, section->sh_name);
+  }
+
+  // Use the default symbol table name section.
+  return getString(dot_strtab_sec, symb->st_name);
+}
+
+template<support::endianness target_endianness, bool is64Bits>
+uint64_t ELFObjectFile<target_endianness, is64Bits>
+                      ::getSymbolAddress(DataRefImpl Symb) const {
+  validateSymbol(Symb);
+  const Elf_Sym  *symb = getSymbol(Symb);
+  const Elf_Shdr *Section;
+  switch (symb->st_shndx) {
+  case ELF::SHN_COMMON:
+   // Undefined symbols have no address yet.
+  case ELF::SHN_UNDEF: return UnknownAddressOrSize;
+  case ELF::SHN_ABS: return symb->st_value;
+  default: Section = getSection(symb->st_shndx);
+  }
+
+  switch (symb->getType()) {
+  case ELF::STT_SECTION: return Section ? Section->sh_addr
+                                        : UnknownAddressOrSize;
+  case ELF::STT_FUNC:
+  case ELF::STT_OBJECT:
+  case ELF::STT_NOTYPE:
+    return symb->st_value;
+  default: return UnknownAddressOrSize;
+  }
+}
+
+template<support::endianness target_endianness, bool is64Bits>
+uint64_t ELFObjectFile<target_endianness, is64Bits>
+                      ::getSymbolSize(DataRefImpl Symb) const {
+  validateSymbol(Symb);
+  const Elf_Sym  *symb = getSymbol(Symb);
+  if (symb->st_size == 0)
+    return UnknownAddressOrSize;
+  return symb->st_size;
+}
+
+template<support::endianness target_endianness, bool is64Bits>
+char ELFObjectFile<target_endianness, is64Bits>
+                  ::getSymbolNMTypeChar(DataRefImpl Symb) const {
+  validateSymbol(Symb);
+  const Elf_Sym  *symb = getSymbol(Symb);
+  const Elf_Shdr *Section = getSection(symb->st_shndx);
+
+  char ret = '?';
+
+  if (Section) {
+    switch (Section->sh_type) {
+    case ELF::SHT_PROGBITS:
+    case ELF::SHT_DYNAMIC:
+      switch (Section->sh_flags) {
+      case (ELF::SHF_ALLOC | ELF::SHF_EXECINSTR):
+        ret = 't'; break;
+      case (ELF::SHF_ALLOC | ELF::SHF_WRITE):
+        ret = 'd'; break;
+      case ELF::SHF_ALLOC:
+      case (ELF::SHF_ALLOC | ELF::SHF_MERGE):
+      case (ELF::SHF_ALLOC | ELF::SHF_MERGE | ELF::SHF_STRINGS):
+        ret = 'r'; break;
+      }
+      break;
+    case ELF::SHT_NOBITS: ret = 'b';
+    }
+  }
+
+  switch (symb->st_shndx) {
+  case ELF::SHN_UNDEF:
+    if (ret == '?')
+      ret = 'U';
+    break;
+  case ELF::SHN_ABS: ret = 'a'; break;
+  case ELF::SHN_COMMON: ret = 'c'; break;
+  }
+
+  switch (symb->getBinding()) {
+  case ELF::STB_GLOBAL: ret = ::toupper(ret); break;
+  case ELF::STB_WEAK:
+    if (symb->st_shndx == ELF::SHN_UNDEF)
+      ret = 'w';
+    else
+      if (symb->getType() == ELF::STT_OBJECT)
+        ret = 'V';
+      else
+        ret = 'W';
+  }
+
+  if (ret == '?' && symb->getType() == ELF::STT_SECTION)
+    return StringSwitch<char>(getSymbolName(Symb))
+      .StartsWith(".debug", 'N')
+      .StartsWith(".note", 'n');
+
+  return ret;
+}
+
+template<support::endianness target_endianness, bool is64Bits>
+bool ELFObjectFile<target_endianness, is64Bits>
+                  ::isSymbolInternal(DataRefImpl Symb) const {
+  validateSymbol(Symb);
+  const Elf_Sym  *symb = getSymbol(Symb);
+
+  if (  symb->getType() == ELF::STT_FILE
+     || symb->getType() == ELF::STT_SECTION)
+    return true;
+  return false;
+}
+
+template<support::endianness target_endianness, bool is64Bits>
+SectionRef ELFObjectFile<target_endianness, is64Bits>
+                        ::getSectionNext(DataRefImpl Sec) const {
+  const uint8_t *sec = *reinterpret_cast<const uint8_t **>(&Sec);
+  sec += Header->e_shentsize;
+  return SectionRef(DataRefImpl(sec), this);
+}
+
+template<support::endianness target_endianness, bool is64Bits>
+StringRef ELFObjectFile<target_endianness, is64Bits>
+                       ::getSectionName(DataRefImpl Sec) const {
+  const Elf_Shdr *sec =
+    *reinterpret_cast<const Elf_Shdr **>(&Sec);
+  return StringRef(getString(dot_shstrtab_sec, sec->sh_name));
+}
+
+template<support::endianness target_endianness, bool is64Bits>
+uint64_t ELFObjectFile<target_endianness, is64Bits>
+                      ::getSectionAddress(DataRefImpl Sec) const {
+  const Elf_Shdr *sec =
+    *reinterpret_cast<const Elf_Shdr **>(&Sec);
+  return sec->sh_addr;
+}
+
+template<support::endianness target_endianness, bool is64Bits>
+uint64_t ELFObjectFile<target_endianness, is64Bits>
+                      ::getSectionSize(DataRefImpl Sec) const {
+  const Elf_Shdr *sec =
+    *reinterpret_cast<const Elf_Shdr **>(&Sec);
+  return sec->sh_size;
+}
+
+template<support::endianness target_endianness, bool is64Bits>
+StringRef ELFObjectFile<target_endianness, is64Bits>
+                       ::getSectionContents(DataRefImpl Sec) const {
+  const Elf_Shdr *sec =
+    *reinterpret_cast<const Elf_Shdr **>(&Sec);
+  const char *start = (char*)base + sec->sh_offset;
+  return StringRef(start, sec->sh_size);
+}
+
+template<support::endianness target_endianness, bool is64Bits>
+bool ELFObjectFile<target_endianness, is64Bits>
+                  ::isSectionText(DataRefImpl Sec) const {
+  const Elf_Shdr *sec =
+    *reinterpret_cast<const Elf_Shdr **>(&Sec);
+  if (sec->sh_flags & ELF::SHF_EXECINSTR)
+    return true;
+  return false;
+}
+
+template<support::endianness target_endianness, bool is64Bits>
+ELFObjectFile<target_endianness, is64Bits>::ELFObjectFile(MemoryBuffer *Object)
+  : ObjectFile(Object)
+  , SectionHeaderTable(0)
+  , dot_shstrtab_sec(0)
+  , dot_strtab_sec(0) {
+  Header = reinterpret_cast<const Elf_Ehdr *>(base);
+
+  if (Header->e_shoff == 0)
+    return;
+
+  SectionHeaderTable =
+    reinterpret_cast<const Elf_Shdr *>(base + Header->e_shoff);
+  uint32_t SectionTableSize = Header->e_shnum * Header->e_shentsize;
+  if (!(  (const uint8_t *)SectionHeaderTable + SectionTableSize
+         <= base + MapFile->getBufferSize()))
+    // FIXME: Proper error handling.
+    report_fatal_error("Section table goes past end of file!");
+
+
+  // To find the symbol tables we walk the section table to find SHT_STMTAB.
+  for (const char *i = reinterpret_cast<const char *>(SectionHeaderTable),
+                  *e = i + Header->e_shnum * Header->e_shentsize;
+                   i != e; i += Header->e_shentsize) {
+    const Elf_Shdr *sh = reinterpret_cast<const Elf_Shdr*>(i);
+    if (sh->sh_type == ELF::SHT_SYMTAB) {
+      SymbolTableSections.push_back(sh);
+    }
+  }
+
+  // Get string table sections.
+  dot_shstrtab_sec = getSection(Header->e_shstrndx);
+  if (dot_shstrtab_sec) {
+    // Verify that the last byte in the string table in a null.
+    if (((const char*)base + dot_shstrtab_sec->sh_offset)
+        [dot_shstrtab_sec->sh_size - 1] != 0)
+      // FIXME: Proper error handling.
+      report_fatal_error("String table must end with a null terminator!");
+  }
+
+  // Merge this into the above loop.
+  for (const char *i = reinterpret_cast<const char *>(SectionHeaderTable),
+                  *e = i + Header->e_shnum * Header->e_shentsize;
+                   i != e; i += Header->e_shentsize) {
+    const Elf_Shdr *sh = reinterpret_cast<const Elf_Shdr*>(i);
+    if (sh->sh_type == ELF::SHT_STRTAB) {
+      StringRef SectionName(getString(dot_shstrtab_sec, sh->sh_name));
+      if (SectionName == ".strtab") {
+        if (dot_strtab_sec != 0)
+          // FIXME: Proper error handling.
+          report_fatal_error("Already found section named .strtab!");
+        dot_strtab_sec = sh;
+        const char *dot_strtab = (const char*)base + sh->sh_offset;
+          if (dot_strtab[sh->sh_size - 1] != 0)
+            // FIXME: Proper error handling.
+            report_fatal_error("String table must end with a null terminator!");
+      }
+    }
+  }
+}
+
+template<support::endianness target_endianness, bool is64Bits>
+ObjectFile::symbol_iterator ELFObjectFile<target_endianness, is64Bits>
+                                         ::begin_symbols() const {
+  ELFDataRefImpl SymbolData;
+  memset(&SymbolData, 0, sizeof(SymbolData));
+  if (SymbolTableSections.size() == 0) {
+    SymbolData.SymbolIndex = std::numeric_limits<uint32_t>::max();
+    SymbolData.SymbolTableSectionIndex = std::numeric_limits<uint32_t>::max();
+  } else {
+    SymbolData.SymbolIndex = 1; // The 0th symbol in ELF is fake.
+    SymbolData.SymbolTableSectionIndex = 0;
+  }
+  return symbol_iterator(
+    SymbolRef(DataRefImpl(*reinterpret_cast<DataRefImpl*>(&SymbolData)), this));
+}
+
+template<support::endianness target_endianness, bool is64Bits>
+ObjectFile::symbol_iterator ELFObjectFile<target_endianness, is64Bits>
+                                         ::end_symbols() const {
+  ELFDataRefImpl SymbolData;
+  memset(&SymbolData, 0, sizeof(SymbolData));
+  SymbolData.SymbolIndex = std::numeric_limits<uint32_t>::max();
+  SymbolData.SymbolTableSectionIndex = std::numeric_limits<uint32_t>::max();
+  return symbol_iterator(
+    SymbolRef(DataRefImpl(*reinterpret_cast<DataRefImpl*>(&SymbolData)), this));
+}
+
+template<support::endianness target_endianness, bool is64Bits>
+ObjectFile::section_iterator ELFObjectFile<target_endianness, is64Bits>
+                                          ::begin_sections() const {
+  return section_iterator(
+    SectionRef(DataRefImpl(base + Header->e_shoff), this));
+}
+
+template<support::endianness target_endianness, bool is64Bits>
+ObjectFile::section_iterator ELFObjectFile<target_endianness, is64Bits>
+                                          ::end_sections() const {
+  return section_iterator(
+    SectionRef(DataRefImpl(base
+                           + Header->e_shoff
+                           + (Header->e_shentsize * Header->e_shnum)), this));
+}
+
+template<support::endianness target_endianness, bool is64Bits>
+uint8_t ELFObjectFile<target_endianness, is64Bits>::getBytesInAddress() const {
+  return 4;
+}
+
+template<support::endianness target_endianness, bool is64Bits>
+StringRef ELFObjectFile<target_endianness, is64Bits>
+                       ::getFileFormatName() const {
+  switch(Header->e_ident[ELF::EI_CLASS]) {
+  case ELF::ELFCLASS32:
+    switch(Header->e_machine) {
+    case ELF::EM_386:
+      return "ELF32-i386";
+    case ELF::EM_X86_64:
+      return "ELF32-x86-64";
+    default:
+      return "ELF32-unknown";
+    }
+  case ELF::ELFCLASS64:
+    switch(Header->e_machine) {
+    case ELF::EM_386:
+      return "ELF64-i386";
+    case ELF::EM_X86_64:
+      return "ELF64-x86-64";
+    default:
+      return "ELF64-unknown";
+    }
+  default:
+    // FIXME: Proper error handling.
+    report_fatal_error("Invalid ELFCLASS!");
+  }
+}
+
+template<support::endianness target_endianness, bool is64Bits>
+unsigned ELFObjectFile<target_endianness, is64Bits>::getArch() const {
+  switch(Header->e_machine) {
+  case ELF::EM_386:
+    return Triple::x86;
+  case ELF::EM_X86_64:
+    return Triple::x86_64;
+  default:
+    return Triple::UnknownArch;
+  }
+}
+
+template<support::endianness target_endianness, bool is64Bits>
+const typename ELFObjectFile<target_endianness, is64Bits>::Elf_Sym *
+ELFObjectFile<target_endianness, is64Bits>::getSymbol(DataRefImpl Symb) const {
+  const ELFDataRefImpl SymbolData = *reinterpret_cast<ELFDataRefImpl *>(&Symb);
+  const Elf_Shdr *sec =
+    SymbolTableSections[SymbolData.SymbolTableSectionIndex];
+  return reinterpret_cast<const Elf_Sym *>(
+           base
+           + sec->sh_offset
+           + (SymbolData.SymbolIndex * sec->sh_entsize));
+}
+
+template<support::endianness target_endianness, bool is64Bits>
+const typename ELFObjectFile<target_endianness, is64Bits>::Elf_Shdr *
+ELFObjectFile<target_endianness, is64Bits>::getSection(DataRefImpl Symb) const {
+  const ELFDataRefImpl SymbolData = *reinterpret_cast<ELFDataRefImpl *>(&Symb);
+  const Elf_Shdr *sec = getSection(SymbolData.SymbolTableSectionIndex);
+  if (sec->sh_type != ELF::SHT_SYMTAB)
+    // FIXME: Proper error handling.
+    report_fatal_error("Invalid symbol table section!");
+  return sec;
+}
+
+template<support::endianness target_endianness, bool is64Bits>
+const typename ELFObjectFile<target_endianness, is64Bits>::Elf_Shdr *
+ELFObjectFile<target_endianness, is64Bits>::getSection(uint16_t index) const {
+  if (index == 0 || index >= ELF::SHN_LORESERVE)
+    return 0;
+  if (!SectionHeaderTable || index >= Header->e_shnum)
+    // FIXME: Proper error handling.
+    report_fatal_error("Invalid section index!");
+
+  return reinterpret_cast<const Elf_Shdr *>(
+         reinterpret_cast<const char *>(SectionHeaderTable)
+         + (index * Header->e_shentsize));
+}
+
+template<support::endianness target_endianness, bool is64Bits>
+const char *ELFObjectFile<target_endianness, is64Bits>
+                         ::getString(uint16_t section,
+                                     ELF::Elf32_Word offset) const {
+  return getString(getSection(section), offset);
+}
+
+template<support::endianness target_endianness, bool is64Bits>
+const char *ELFObjectFile<target_endianness, is64Bits>
+                         ::getString(const Elf_Shdr *section,
+                                     ELF::Elf32_Word offset) const {
+  assert(section && section->sh_type == ELF::SHT_STRTAB && "Invalid section!");
+  if (offset >= section->sh_size)
+    // FIXME: Proper error handling.
+    report_fatal_error("Sybol name offset outside of string table!");
+  return (const char *)base + section->sh_offset + offset;
+}
+
+// EI_CLASS, EI_DATA.
+static std::pair<unsigned char, unsigned char>
+getElfArchType(MemoryBuffer *Object) {
+  if (Object->getBufferSize() < ELF::EI_NIDENT)
+    return std::make_pair((uint8_t)ELF::ELFCLASSNONE,(uint8_t)ELF::ELFDATANONE);
+  return std::make_pair( (uint8_t)Object->getBufferStart()[ELF::EI_CLASS]
+                       , (uint8_t)Object->getBufferStart()[ELF::EI_DATA]);
+}
+
+namespace llvm {
+
+  ObjectFile *ObjectFile::createELFObjectFile(MemoryBuffer *Object) {
+    std::pair<unsigned char, unsigned char> Ident = getElfArchType(Object);
+    if (Ident.first == ELF::ELFCLASS32 && Ident.second == ELF::ELFDATA2LSB)
+      return new ELFObjectFile<support::little, false>(Object);
+    else if (Ident.first == ELF::ELFCLASS32 && Ident.second == ELF::ELFDATA2MSB)
+      return new ELFObjectFile<support::big, false>(Object);
+    else if (Ident.first == ELF::ELFCLASS64 && Ident.second == ELF::ELFDATA2LSB)
+      return new ELFObjectFile<support::little, true>(Object);
+    else if (Ident.first == ELF::ELFCLASS64 && Ident.second == ELF::ELFDATA2MSB)
+      return new ELFObjectFile<support::big, true>(Object);
+    // FIXME: Proper error handling.
+    report_fatal_error("Not an ELF object file!");
+  }
+
+} // end namespace llvm
diff --git a/lib/Object/ObjectFile.cpp b/lib/Object/ObjectFile.cpp
index 01b129f9bb..161ae3a083 100644
--- a/lib/Object/ObjectFile.cpp
+++ b/lib/Object/ObjectFile.cpp
@@ -45,7 +45,7 @@ ObjectFile *ObjectFile::createObjectFile(MemoryBuffer *Object) {
     case sys::ELF_Executable_FileType:
     case sys::ELF_SharedObject_FileType:
     case sys::ELF_Core_FileType:
-        return 0;
+      return createELFObjectFile(Object);
     case sys::Mach_O_Object_FileType:
     case sys::Mach_O_Executable_FileType:
     case sys::Mach_O_FixedVirtualMemorySharedLib_FileType: