Object: Add proper error handling.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@133872 91177308-0d34-0410-b5e6-96231b3b80d8
2025-09-24 23:28:41 +00:00 · 2011-06-25 17:55:23 +00:00
parent 76fb9b0e5f
commit 25b15777df
10 changed files with 563 additions and 271 deletions
--- a/lib/Object/COFFObjectFile.cpp
+++ b/lib/Object/COFFObjectFile.cpp
@@ -25,74 +25,165 @@ using support::ulittle32_t;
 using support::little16_t;
 }

-SymbolRef COFFObjectFile::getSymbolNext(DataRefImpl Symb) const {
-  const coff_symbol *symb = reinterpret_cast<const coff_symbol*>(Symb.p);
-  symb += 1 + symb->NumberOfAuxSymbols;
-  Symb.p = reinterpret_cast<intptr_t>(symb);
-  return SymbolRef(Symb, this);
+namespace {
+// Returns false if size is greater than the buffer size. And sets ec.
+bool checkSize(const MemoryBuffer *m, error_code &ec, uint64_t size) {
+  if (m->getBufferSize() < size) {
+    ec = object_error::unexpected_eof;
+    return false;
+  }
+  return true;
 }

-StringRef COFFObjectFile::getSymbolName(DataRefImpl Symb) const {
-  const coff_symbol *symb = reinterpret_cast<const coff_symbol*>(Symb.p);
+// Returns false if any bytes in [addr, addr + size) fall outsize of m.
+bool checkAddr(const MemoryBuffer *m,
+               error_code &ec,
+               uintptr_t addr,
+               uint64_t size) {
+  if (addr + size < addr ||
+      addr + size < size ||
+      addr + size > uintptr_t(m->getBufferEnd())) {
+    ec = object_error::unexpected_eof;
+    return false;
+  }
+  return true;
+}
+}
+
+const coff_symbol *COFFObjectFile::toSymb(DataRefImpl Symb) const {
+  const coff_symbol *addr = reinterpret_cast<const coff_symbol*>(Symb.p);
+
+# ifndef NDEBUG
+  // Verify that the symbol points to a valid entry in the symbol table.
+  uintptr_t offset = uintptr_t(addr) - uintptr_t(base());
+  if (offset < Header->PointerToSymbolTable
+      || offset >= Header->PointerToSymbolTable
+         + (Header->NumberOfSymbols * sizeof(coff_symbol)))
+    report_fatal_error("Symbol was outside of symbol table.");
+
+  assert((offset - Header->PointerToSymbolTable) % sizeof(coff_symbol)
+         == 0 && "Symbol did not point to the beginning of a symbol");
+# endif
+
+  return addr;
+}
+
+const coff_section *COFFObjectFile::toSec(DataRefImpl Sec) const {
+  const coff_section *addr = reinterpret_cast<const coff_section*>(Sec.p);
+
+# ifndef NDEBUG
+  // Verify that the section points to a valid entry in the section table.
+  if (addr < SectionTable
+      || addr >= (SectionTable + Header->NumberOfSections))
+    report_fatal_error("Section was outside of section table.");
+
+  uintptr_t offset = uintptr_t(addr) - uintptr_t(SectionTable);
+  assert(offset % sizeof(coff_section) == 0 &&
+         "Section did not point to the beginning of a section");
+# endif
+
+  return addr;
+}
+
+error_code COFFObjectFile::getSymbolNext(DataRefImpl Symb,
+                                         SymbolRef &Result) const {
+  const coff_symbol *symb = toSymb(Symb);
+  symb += 1 + symb->NumberOfAuxSymbols;
+  Symb.p = reinterpret_cast<uintptr_t>(symb);
+  Result = SymbolRef(Symb, this);
+  return object_error::success;
+}
+
+ error_code COFFObjectFile::getSymbolName(DataRefImpl Symb,
+                                          StringRef &Result) const {
+  const coff_symbol *symb = toSymb(Symb);
  // Check for string table entry. First 4 bytes are 0.
  if (symb->Name.Offset.Zeroes == 0) {
    uint32_t Offset = symb->Name.Offset.Offset;
-    return StringRef(getString(Offset));
+    if (error_code ec = getString(Offset, Result))
+      return ec;
+    return object_error::success;
  }

  if (symb->Name.ShortName[7] == 0)
    // Null terminated, let ::strlen figure out the length.
-    return StringRef(symb->Name.ShortName);
-  // Not null terminated, use all 8 bytes.
-  return StringRef(symb->Name.ShortName, 8);
+    Result = StringRef(symb->Name.ShortName);
+  else
+    // Not null terminated, use all 8 bytes.
+    Result = StringRef(symb->Name.ShortName, 8);
+  return object_error::success;
 }

-uint64_t COFFObjectFile::getSymbolAddress(DataRefImpl Symb) const {
-  const coff_symbol *symb = reinterpret_cast<const coff_symbol*>(Symb.p);
-  const coff_section *Section = getSection(symb->SectionNumber);
-  char Type = getSymbolNMTypeChar(Symb);
+error_code COFFObjectFile::getSymbolAddress(DataRefImpl Symb,
+                                            uint64_t &Result) const {
+  const coff_symbol *symb = toSymb(Symb);
+  const coff_section *Section;
+  if (error_code ec = getSection(symb->SectionNumber, Section))
+    return ec;
+  char Type;
+  if (error_code ec = getSymbolNMTypeChar(Symb, Type))
+    return ec;
  if (Type == 'U' || Type == 'w')
-    return UnknownAddressOrSize;
-  if (Section)
-    return Section->VirtualAddress + symb->Value;
-  return symb->Value;
+    Result = UnknownAddressOrSize;
+  else if (Section)
+    Result = Section->VirtualAddress + symb->Value;
+  else
+    Result = symb->Value;
+  return object_error::success;
 }

-uint64_t COFFObjectFile::getSymbolSize(DataRefImpl Symb) const {
+error_code COFFObjectFile::getSymbolSize(DataRefImpl Symb,
+                                         uint64_t &Result) const {
  // FIXME: Return the correct size. This requires looking at all the symbols
  //        in the same section as this symbol, and looking for either the next
  //        symbol, or the end of the section.
-  const coff_symbol *symb = reinterpret_cast<const coff_symbol*>(Symb.p);
-  const coff_section *Section = getSection(symb->SectionNumber);
-  char Type = getSymbolNMTypeChar(Symb);
+  const coff_symbol *symb = toSymb(Symb);
+  const coff_section *Section;
+  if (error_code ec = getSection(symb->SectionNumber, Section))
+    return ec;
+  char Type;
+  if (error_code ec = getSymbolNMTypeChar(Symb, Type))
+    return ec;
  if (Type == 'U' || Type == 'w')
-    return UnknownAddressOrSize;
-  if (Section)
-    return Section->SizeOfRawData - symb->Value;
-  return 0;
+    Result = UnknownAddressOrSize;
+  else if (Section)
+    Result = Section->SizeOfRawData - symb->Value;
+  else
+    Result = 0;
+  return object_error::success;
 }

-char COFFObjectFile::getSymbolNMTypeChar(DataRefImpl Symb) const {
-  const coff_symbol *symb = reinterpret_cast<const coff_symbol*>(Symb.p);
-  char ret = StringSwitch<char>(getSymbolName(Symb))
+error_code COFFObjectFile::getSymbolNMTypeChar(DataRefImpl Symb,
+                                               char &Result) const {
+  const coff_symbol *symb = toSymb(Symb);
+  StringRef name;
+  if (error_code ec = getSymbolName(Symb, name))
+    return ec;
+  char ret = StringSwitch<char>(name)
    .StartsWith(".debug", 'N')
    .StartsWith(".sxdata", 'N')
    .Default('?');

-  if (ret != '?')
-    return ret;
+  if (ret != '?') {
+    Result = ret;
+    return object_error::success;
+  }

  uint32_t Characteristics = 0;
-  if (const coff_section *Section = getSection(symb->SectionNumber)) {
+  if (symb->SectionNumber > 0) {
+    const coff_section *Section;
+    if (error_code ec = getSection(symb->SectionNumber, Section))
+      return ec;
    Characteristics = Section->Characteristics;
  }

  switch (symb->SectionNumber) {
  case COFF::IMAGE_SYM_UNDEFINED:
    // Check storage classes.
-    if (symb->StorageClass == COFF::IMAGE_SYM_CLASS_WEAK_EXTERNAL)
-      return 'w'; // Don't do ::toupper.
-    else
+    if (symb->StorageClass == COFF::IMAGE_SYM_CLASS_WEAK_EXTERNAL) {
+      Result = 'w';
+      return object_error::success; // Don't do ::toupper.
+    } else
      ret = 'u';
    break;
  case COFF::IMAGE_SYM_ABSOLUTE:
@@ -124,22 +215,28 @@ char COFFObjectFile::getSymbolNMTypeChar(DataRefImpl Symb) const {
  if (symb->StorageClass == COFF::IMAGE_SYM_CLASS_EXTERNAL)
    ret = ::toupper(ret);

-  return ret;
+  Result = ret;
+  return object_error::success;
 }

-bool COFFObjectFile::isSymbolInternal(DataRefImpl Symb) const {
-  return false;
+error_code COFFObjectFile::isSymbolInternal(DataRefImpl Symb,
+                                            bool &Result) const {
+  Result = false;
+  return object_error::success;
 }

-SectionRef COFFObjectFile::getSectionNext(DataRefImpl Sec) const {
-  const coff_section *sec = reinterpret_cast<const coff_section*>(Sec.p);
+error_code COFFObjectFile::getSectionNext(DataRefImpl Sec,
+                                          SectionRef &Result) const {
+  const coff_section *sec = toSec(Sec);
  sec += 1;
-  Sec.p = reinterpret_cast<intptr_t>(sec);
-  return SectionRef(Sec, this);
+  Sec.p = reinterpret_cast<uintptr_t>(sec);
+  Result = SectionRef(Sec, this);
+  return object_error::success;
 }

-StringRef COFFObjectFile::getSectionName(DataRefImpl Sec) const {
-  const coff_section *sec = reinterpret_cast<const coff_section*>(Sec.p);
+error_code COFFObjectFile::getSectionName(DataRefImpl Sec,
+                                          StringRef &Result) const {
+  const coff_section *sec = toSec(Sec);
  StringRef name;
  if (sec->Name[7] == 0)
    // Null terminated, let ::strlen figure out the length.
@@ -152,66 +249,117 @@ StringRef COFFObjectFile::getSectionName(DataRefImpl Sec) const {
  if (name[0] == '/') {
    uint32_t Offset;
    name.substr(1).getAsInteger(10, Offset);
-    return StringRef(getString(Offset));
+    if (error_code ec = getString(Offset, name))
+      return ec;
  }

-  // It's just a normal name.
-  return name;
+  Result = name;
+  return object_error::success;
 }

-uint64_t COFFObjectFile::getSectionAddress(DataRefImpl Sec) const {
-  const coff_section *sec = reinterpret_cast<const coff_section*>(Sec.p);
-  return sec->VirtualAddress;
+error_code COFFObjectFile::getSectionAddress(DataRefImpl Sec,
+                                             uint64_t &Result) const {
+  const coff_section *sec = toSec(Sec);
+  Result = sec->VirtualAddress;
+  return object_error::success;
 }

-uint64_t COFFObjectFile::getSectionSize(DataRefImpl Sec) const {
-  const coff_section *sec = reinterpret_cast<const coff_section*>(Sec.p);
-  return sec->SizeOfRawData;
+error_code COFFObjectFile::getSectionSize(DataRefImpl Sec,
+                                          uint64_t &Result) const {
+  const coff_section *sec = toSec(Sec);
+  Result = sec->SizeOfRawData;
+  return object_error::success;
 }

-StringRef COFFObjectFile::getSectionContents(DataRefImpl Sec) const {
-  const coff_section *sec = reinterpret_cast<const coff_section*>(Sec.p);
-  return StringRef(reinterpret_cast<const char *>(base()
-                   + sec->PointerToRawData),
-                   sec->SizeOfRawData);
+error_code COFFObjectFile::getSectionContents(DataRefImpl Sec,
+                                              StringRef &Result) const {
+  const coff_section *sec = toSec(Sec);
+  // The only thing that we need to verify is that the contents is contained
+  // within the file bounds. We don't need to make sure it doesn't cover other
+  // data, as there's nothing that says that is not allowed.
+  uintptr_t con_start = uintptr_t(base()) + sec->PointerToRawData;
+  uintptr_t con_end = con_start + sec->SizeOfRawData;
+  if (con_end >= uintptr_t(Data->getBufferEnd()))
+    return object_error::parse_failed;
+  Result = StringRef(reinterpret_cast<const char*>(con_start),
+                     sec->SizeOfRawData);
+  return object_error::success;
 }

-bool COFFObjectFile::isSectionText(DataRefImpl Sec) const {
-  const coff_section *sec = reinterpret_cast<const coff_section*>(Sec.p);
-  return sec->Characteristics & COFF::IMAGE_SCN_CNT_CODE;
+error_code COFFObjectFile::isSectionText(DataRefImpl Sec,
+                                         bool &Result) const {
+  const coff_section *sec = toSec(Sec);
+  Result = sec->Characteristics & COFF::IMAGE_SCN_CNT_CODE;
+  return object_error::success;
 }

 COFFObjectFile::COFFObjectFile(MemoryBuffer *Object, error_code &ec)
  : ObjectFile(Binary::isCOFF, Object, ec) {
+  // Check that we at least have enough room for a header.
+  if (!checkSize(Data, ec, sizeof(coff_file_header))) return;

-  HeaderOff = 0;
+  // The actual starting location of the COFF header in the file. This can be
+  // non-zero in PE/COFF files.
+  uint64_t HeaderStart = 0;

+  // Check if this is a PE/COFF file.
  if (base()[0] == 0x4d && base()[1] == 0x5a) {
    // PE/COFF, seek through MS-DOS compatibility stub and 4-byte
    // PE signature to find 'normal' COFF header.
-    HeaderOff += *reinterpret_cast<const ulittle32_t *>(base() + 0x3c);
-    HeaderOff += 4;
+    if (!checkSize(Data, ec, 0x3c + 8)) return;
+    HeaderStart += *reinterpret_cast<const ulittle32_t *>(base() + 0x3c);
+    // Check the PE header. ("PE\0\0")
+    if (StringRef(reinterpret_cast<const char *>(base() + HeaderStart), 4)
+        != "PE\0\0") {
+      ec = object_error::parse_failed;
+      return;
+    }
+    HeaderStart += 4; // Skip the PE Header.
  }

-  Header = reinterpret_cast<const coff_file_header *>(base() + HeaderOff);
+  Header = reinterpret_cast<const coff_file_header *>(base() + HeaderStart);
+  if (!checkAddr(Data, ec, uintptr_t(Header), sizeof(coff_file_header)))
+    return;
+  
  SectionTable =
    reinterpret_cast<const coff_section *>( base()
-                                          + HeaderOff
+                                          + HeaderStart
                                          + sizeof(coff_file_header)
                                          + Header->SizeOfOptionalHeader);
+  if (!checkAddr(Data, ec, uintptr_t(SectionTable),
+                 Header->NumberOfSections * sizeof(coff_section)))
+    return;
+
  SymbolTable =
    reinterpret_cast<const coff_symbol *>(base()
-    + Header->PointerToSymbolTable);
+                                          + Header->PointerToSymbolTable);
+  if (!checkAddr(Data, ec, uintptr_t(SymbolTable),
+                 Header->NumberOfSymbols * sizeof(coff_symbol)))
+    return;

  // Find string table.
  StringTable = reinterpret_cast<const char *>(base())
-              + Header->PointerToSymbolTable
-              + Header->NumberOfSymbols * 18;
+                + Header->PointerToSymbolTable
+                + Header->NumberOfSymbols * sizeof(coff_symbol);
+  if (!checkAddr(Data, ec, uintptr_t(StringTable), sizeof(ulittle32_t)))
+    return;
+
+  StringTableSize = *reinterpret_cast<const ulittle32_t *>(StringTable);
+  if (!checkAddr(Data, ec, uintptr_t(StringTable), StringTableSize))
+    return;
+  // Check that the string table is null terminated if has any in it.
+  if (StringTableSize < 4
+      || (StringTableSize > 4 && StringTable[StringTableSize - 1] != 0)) {
+    ec = object_error::parse_failed;
+    return;
+  }
+  
+  ec = object_error::success;
 }

 ObjectFile::symbol_iterator COFFObjectFile::begin_symbols() const {
  DataRefImpl ret;
-  memset(&ret, 0, sizeof(DataRefImpl));
+  std::memset(&ret, 0, sizeof(DataRefImpl));
  ret.p = reinterpret_cast<intptr_t>(SymbolTable);
  return symbol_iterator(SymbolRef(ret, this));
 }
@@ -219,21 +367,21 @@ ObjectFile::symbol_iterator COFFObjectFile::begin_symbols() const {
 ObjectFile::symbol_iterator COFFObjectFile::end_symbols() const {
  // The symbol table ends where the string table begins.
  DataRefImpl ret;
-  memset(&ret, 0, sizeof(DataRefImpl));
+  std::memset(&ret, 0, sizeof(DataRefImpl));
  ret.p = reinterpret_cast<intptr_t>(StringTable);
  return symbol_iterator(SymbolRef(ret, this));
 }

 ObjectFile::section_iterator COFFObjectFile::begin_sections() const {
  DataRefImpl ret;
-  memset(&ret, 0, sizeof(DataRefImpl));
+  std::memset(&ret, 0, sizeof(DataRefImpl));
  ret.p = reinterpret_cast<intptr_t>(SectionTable);
  return section_iterator(SectionRef(ret, this));
 }

 ObjectFile::section_iterator COFFObjectFile::end_sections() const {
  DataRefImpl ret;
-  memset(&ret, 0, sizeof(DataRefImpl));
+  std::memset(&ret, 0, sizeof(DataRefImpl));
  ret.p = reinterpret_cast<intptr_t>(SectionTable + Header->NumberOfSections);
  return section_iterator(SectionRef(ret, this));
 }
@@ -264,18 +412,30 @@ unsigned COFFObjectFile::getArch() const {
  }
 }

-const coff_section *COFFObjectFile::getSection(std::size_t index) const {
-  if (index > 0 && index <= Header->NumberOfSections)
-    return SectionTable + (index - 1);
-  return 0;
+error_code COFFObjectFile::getSection(int32_t index,
+                                      const coff_section *&Result) const {
+  // Check for special index values.
+  if (index == COFF::IMAGE_SYM_UNDEFINED ||
+      index == COFF::IMAGE_SYM_ABSOLUTE ||
+      index == COFF::IMAGE_SYM_DEBUG)
+    Result = NULL;
+  else if (index > 0 && index <= Header->NumberOfSections)
+    // We already verified the section table data, so no need to check again.
+    Result = SectionTable + (index - 1);
+  else
+    return object_error::parse_failed;
+  return object_error::success;
 }

-const char *COFFObjectFile::getString(std::size_t offset) const {
-  const ulittle32_t *StringTableSize =
-    reinterpret_cast<const ulittle32_t *>(StringTable);
-  if (offset < *StringTableSize)
-    return StringTable + offset;
-  return 0;
+error_code COFFObjectFile::getString(uint32_t offset,
+                                     StringRef &Result) const {
+  if (StringTableSize <= 4)
+    // Tried to get a string from an empty string table.
+    return object_error::parse_failed;
+  if (offset >= StringTableSize)
+    return object_error::unexpected_eof;
+  Result = StringRef(StringTable + offset);
+  return object_error::success;
 }

 namespace llvm {
--- a/lib/Object/ELFObjectFile.cpp
+++ b/lib/Object/ELFObjectFile.cpp
@@ -222,19 +222,19 @@ class ELFObjectFile : public ObjectFile {
  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 error_code getSymbolNext(DataRefImpl Symb, SymbolRef &Res) const;
+  virtual error_code getSymbolName(DataRefImpl Symb, StringRef &Res) const;
+  virtual error_code getSymbolAddress(DataRefImpl Symb, uint64_t &Res) const;
+  virtual error_code getSymbolSize(DataRefImpl Symb, uint64_t &Res) const;
+  virtual error_code getSymbolNMTypeChar(DataRefImpl Symb, char &Res) const;
+  virtual error_code isSymbolInternal(DataRefImpl Symb, bool &Res) 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;
+  virtual error_code getSectionNext(DataRefImpl Sec, SectionRef &Res) const;
+  virtual error_code getSectionName(DataRefImpl Sec, StringRef &Res) const;
+  virtual error_code getSectionAddress(DataRefImpl Sec, uint64_t &Res) const;
+  virtual error_code getSectionSize(DataRefImpl Sec, uint64_t &Res) const;
+  virtual error_code getSectionContents(DataRefImpl Sec, StringRef &Res) const;
+  virtual error_code isSectionText(DataRefImpl Sec, bool &Res) const;

 public:
  ELFObjectFile(MemoryBuffer *Object, error_code &ec);
@@ -269,8 +269,9 @@ void ELFObjectFile<target_endianness, is64Bits>
 }

 template<support::endianness target_endianness, bool is64Bits>
-SymbolRef ELFObjectFile<target_endianness, is64Bits>
-                       ::getSymbolNext(DataRefImpl Symb) const {
+error_code ELFObjectFile<target_endianness, is64Bits>
+                        ::getSymbolNext(DataRefImpl Symb,
+                                        SymbolRef &Result) const {
  validateSymbol(Symb);
  const Elf_Shdr *SymbolTableSection = SymbolTableSections[Symb.d.b];

@@ -287,63 +288,80 @@ SymbolRef ELFObjectFile<target_endianness, is64Bits>
    }
  }

-  return SymbolRef(Symb, this);
+  Result = SymbolRef(Symb, this);
+  return object_error::success;
 }

 template<support::endianness target_endianness, bool is64Bits>
-StringRef ELFObjectFile<target_endianness, is64Bits>
-                       ::getSymbolName(DataRefImpl Symb) const {
+error_code ELFObjectFile<target_endianness, is64Bits>
+                        ::getSymbolName(DataRefImpl Symb,
+                                        StringRef &Result) 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);
+      Result = "";
+    else
+      Result = getString(dot_shstrtab_sec, section->sh_name);
+    return object_error::success;
  }

  // Use the default symbol table name section.
-  return getString(dot_strtab_sec, symb->st_name);
+  Result = getString(dot_strtab_sec, symb->st_name);
+  return object_error::success;
 }

 template<support::endianness target_endianness, bool is64Bits>
-uint64_t ELFObjectFile<target_endianness, is64Bits>
-                      ::getSymbolAddress(DataRefImpl Symb) const {
+error_code ELFObjectFile<target_endianness, is64Bits>
+                        ::getSymbolAddress(DataRefImpl Symb,
+                                           uint64_t &Result) 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;
+  case ELF::SHN_UNDEF:
+    Result = UnknownAddressOrSize;
+    return object_error::success;
+  case ELF::SHN_ABS:
+    Result = symb->st_value;
+    return object_error::success;
  default: Section = getSection(symb->st_shndx);
  }

  switch (symb->getType()) {
-  case ELF::STT_SECTION: return Section ? Section->sh_addr
-                                        : UnknownAddressOrSize;
+  case ELF::STT_SECTION:
+    Result = Section ? Section->sh_addr : UnknownAddressOrSize;
+    return object_error::success;
  case ELF::STT_FUNC:
  case ELF::STT_OBJECT:
  case ELF::STT_NOTYPE:
-    return symb->st_value;
-  default: return UnknownAddressOrSize;
+    Result = symb->st_value;
+    return object_error::success;
+  default:
+    Result = UnknownAddressOrSize;
+    return object_error::success;
  }
 }

 template<support::endianness target_endianness, bool is64Bits>
-uint64_t ELFObjectFile<target_endianness, is64Bits>
-                      ::getSymbolSize(DataRefImpl Symb) const {
+error_code ELFObjectFile<target_endianness, is64Bits>
+                        ::getSymbolSize(DataRefImpl Symb,
+                                        uint64_t &Result) const {
  validateSymbol(Symb);
  const Elf_Sym  *symb = getSymbol(Symb);
  if (symb->st_size == 0)
-    return UnknownAddressOrSize;
-  return symb->st_size;
+    Result = UnknownAddressOrSize;
+  Result = symb->st_size;
+  return object_error::success;
 }

 template<support::endianness target_endianness, bool is64Bits>
-char ELFObjectFile<target_endianness, is64Bits>
-                  ::getSymbolNMTypeChar(DataRefImpl Symb) const {
+error_code ELFObjectFile<target_endianness, is64Bits>
+                        ::getSymbolNMTypeChar(DataRefImpl Symb,
+                                              char &Result) const {
  validateSymbol(Symb);
  const Elf_Sym  *symb = getSymbol(Symb);
  const Elf_Shdr *Section = getSection(symb->st_shndx);
@@ -390,71 +408,91 @@ char ELFObjectFile<target_endianness, is64Bits>
        ret = 'W';
  }

-  if (ret == '?' && symb->getType() == ELF::STT_SECTION)
-    return StringSwitch<char>(getSymbolName(Symb))
+  if (ret == '?' && symb->getType() == ELF::STT_SECTION) {
+    StringRef name;
+    if (error_code ec = getSymbolName(Symb, name))
+      return ec;
+    Result = StringSwitch<char>(name)
      .StartsWith(".debug", 'N')
      .StartsWith(".note", 'n');
+    return object_error::success;
+  }

-  return ret;
+  Result = ret;
+  return object_error::success;
 }

 template<support::endianness target_endianness, bool is64Bits>
-bool ELFObjectFile<target_endianness, is64Bits>
-                  ::isSymbolInternal(DataRefImpl Symb) const {
+error_code ELFObjectFile<target_endianness, is64Bits>
+                        ::isSymbolInternal(DataRefImpl Symb,
+                                           bool &Result) const {
  validateSymbol(Symb);
  const Elf_Sym  *symb = getSymbol(Symb);

  if (  symb->getType() == ELF::STT_FILE
     || symb->getType() == ELF::STT_SECTION)
-    return true;
-  return false;
+    Result = true;
+  Result = false;
+  return object_error::success;
 }

 template<support::endianness target_endianness, bool is64Bits>
-SectionRef ELFObjectFile<target_endianness, is64Bits>
-                        ::getSectionNext(DataRefImpl Sec) const {
+error_code ELFObjectFile<target_endianness, is64Bits>
+                        ::getSectionNext(DataRefImpl Sec, SectionRef &Result) const {
  const uint8_t *sec = reinterpret_cast<const uint8_t *>(Sec.p);
  sec += Header->e_shentsize;
  Sec.p = reinterpret_cast<intptr_t>(sec);
-  return SectionRef(Sec, this);
+  Result = SectionRef(Sec, this);
+  return object_error::success;
 }

 template<support::endianness target_endianness, bool is64Bits>
-StringRef ELFObjectFile<target_endianness, is64Bits>
-                       ::getSectionName(DataRefImpl Sec) const {
+error_code ELFObjectFile<target_endianness, is64Bits>
+                        ::getSectionName(DataRefImpl Sec,
+                                         StringRef &Result) const {
  const Elf_Shdr *sec = reinterpret_cast<const Elf_Shdr *>(Sec.p);
-  return StringRef(getString(dot_shstrtab_sec, sec->sh_name));
+  Result = StringRef(getString(dot_shstrtab_sec, sec->sh_name));
+  return object_error::success;
 }

 template<support::endianness target_endianness, bool is64Bits>
-uint64_t ELFObjectFile<target_endianness, is64Bits>
-                      ::getSectionAddress(DataRefImpl Sec) const {
+error_code ELFObjectFile<target_endianness, is64Bits>
+                        ::getSectionAddress(DataRefImpl Sec,
+                                            uint64_t &Result) const {
  const Elf_Shdr *sec = reinterpret_cast<const Elf_Shdr *>(Sec.p);
-  return sec->sh_addr;
+  Result = sec->sh_addr;
+  return object_error::success;
 }

 template<support::endianness target_endianness, bool is64Bits>
-uint64_t ELFObjectFile<target_endianness, is64Bits>
-                      ::getSectionSize(DataRefImpl Sec) const {
+error_code ELFObjectFile<target_endianness, is64Bits>
+                        ::getSectionSize(DataRefImpl Sec,
+                                         uint64_t &Result) const {
  const Elf_Shdr *sec = reinterpret_cast<const Elf_Shdr *>(Sec.p);
-  return sec->sh_size;
+  Result = sec->sh_size;
+  return object_error::success;
 }

 template<support::endianness target_endianness, bool is64Bits>
-StringRef ELFObjectFile<target_endianness, is64Bits>
-                       ::getSectionContents(DataRefImpl Sec) const {
+error_code ELFObjectFile<target_endianness, is64Bits>
+                        ::getSectionContents(DataRefImpl Sec,
+                                             StringRef &Result) const {
  const Elf_Shdr *sec = reinterpret_cast<const Elf_Shdr *>(Sec.p);
-  const char *start = (char*)base() + sec->sh_offset;
-  return StringRef(start, sec->sh_size);
+  const char *start = (const char*)base() + sec->sh_offset;
+  Result = StringRef(start, sec->sh_size);
+  return object_error::success;
 }

 template<support::endianness target_endianness, bool is64Bits>
-bool ELFObjectFile<target_endianness, is64Bits>
-                  ::isSectionText(DataRefImpl Sec) const {
+error_code ELFObjectFile<target_endianness, is64Bits>
+                        ::isSectionText(DataRefImpl Sec,
+                                        bool &Result) const {
  const Elf_Shdr *sec = reinterpret_cast<const Elf_Shdr *>(Sec.p);
  if (sec->sh_flags & ELF::SHF_EXECINSTR)
-    return true;
-  return false;
+    Result = true;
+  else
+    Result = false;
+  return object_error::success;
 }

 template<support::endianness target_endianness, bool is64Bits>
--- a/lib/Object/Error.cpp
+++ b/lib/Object/Error.cpp
@@ -37,6 +37,8 @@ std::string _object_error_category::message(int ev) const {
    return "The file was not recognized as a valid object file";
  case object_error::parse_failed:
    return "Invalid data was encountered while parsing the file";
+  case object_error::unexpected_eof:
+    return "The end of the file was unexpectedly encountered";
  default:
    llvm_unreachable("An enumerator of object_error does not have a message "
                     "defined.");
--- a/lib/Object/MachOObjectFile.cpp
+++ b/lib/Object/MachOObjectFile.cpp
@@ -47,19 +47,19 @@ public:
  virtual unsigned getArch() 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 error_code getSymbolNext(DataRefImpl Symb, SymbolRef &Res) const;
+  virtual error_code getSymbolName(DataRefImpl Symb, StringRef &Res) const;
+  virtual error_code getSymbolAddress(DataRefImpl Symb, uint64_t &Res) const;
+  virtual error_code getSymbolSize(DataRefImpl Symb, uint64_t &Res) const;
+  virtual error_code getSymbolNMTypeChar(DataRefImpl Symb, char &Res) const;
+  virtual error_code isSymbolInternal(DataRefImpl Symb, bool &Res) 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;
+  virtual error_code getSectionNext(DataRefImpl Sec, SectionRef &Res) const;
+  virtual error_code getSectionName(DataRefImpl Sec, StringRef &Res) const;
+  virtual error_code getSectionAddress(DataRefImpl Sec, uint64_t &Res) const;
+  virtual error_code getSectionSize(DataRefImpl Sec, uint64_t &Res) const;
+  virtual error_code getSectionContents(DataRefImpl Sec, StringRef &Res) const;
+  virtual error_code isSectionText(DataRefImpl Sec, bool &Res) const;

 private:
  MachOObject *MachOObj;
@@ -115,29 +115,38 @@ void MachOObjectFile::getSymbolTableEntry(DataRefImpl DRI,
 }


-SymbolRef MachOObjectFile::getSymbolNext(DataRefImpl DRI) const {
+error_code MachOObjectFile::getSymbolNext(DataRefImpl DRI,
+                                          SymbolRef &Result) const {
  DRI.d.b++;
  moveToNextSymbol(DRI);
-  return SymbolRef(DRI, this);
+  Result = SymbolRef(DRI, this);
+  return object_error::success;
 }

-StringRef MachOObjectFile::getSymbolName(DataRefImpl DRI) const {
+error_code MachOObjectFile::getSymbolName(DataRefImpl DRI,
+                                          StringRef &Result) const {
  InMemoryStruct<macho::SymbolTableEntry> Entry;
  getSymbolTableEntry(DRI, Entry);
-  return MachOObj->getStringAtIndex(Entry->StringIndex);
+  Result = MachOObj->getStringAtIndex(Entry->StringIndex);
+  return object_error::success;
 }

-uint64_t MachOObjectFile::getSymbolAddress(DataRefImpl DRI) const {
+error_code MachOObjectFile::getSymbolAddress(DataRefImpl DRI,
+                                             uint64_t &Result) const {
  InMemoryStruct<macho::SymbolTableEntry> Entry;
  getSymbolTableEntry(DRI, Entry);
-  return Entry->Value;
+  Result = Entry->Value;
+  return object_error::success;
 }

-uint64_t MachOObjectFile::getSymbolSize(DataRefImpl DRI) const {
-  return UnknownAddressOrSize;
+error_code MachOObjectFile::getSymbolSize(DataRefImpl DRI,
+                                          uint64_t &Result) const {
+  Result = UnknownAddressOrSize;
+  return object_error::success;
 }

-char MachOObjectFile::getSymbolNMTypeChar(DataRefImpl DRI) const {
+error_code MachOObjectFile::getSymbolNMTypeChar(DataRefImpl DRI,
+                                                char &Result) const {
  InMemoryStruct<macho::SymbolTableEntry> Entry;
  getSymbolTableEntry(DRI, Entry);

@@ -157,13 +166,16 @@ char MachOObjectFile::getSymbolNMTypeChar(DataRefImpl DRI) const {

  if (Entry->Flags & (macho::STF_External | macho::STF_PrivateExtern))
    Char = toupper(Char);
-  return Char;
+  Result = Char;
+  return object_error::success;
 }

-bool MachOObjectFile::isSymbolInternal(DataRefImpl DRI) const {
+error_code MachOObjectFile::isSymbolInternal(DataRefImpl DRI,
+                                             bool &Result) const {
  InMemoryStruct<macho::SymbolTableEntry> Entry;
  getSymbolTableEntry(DRI, Entry);
-  return Entry->Flags & macho::STF_StabsEntryMask;
+  Result = Entry->Flags & macho::STF_StabsEntryMask;
+  return object_error::success;
 }

 ObjectFile::symbol_iterator MachOObjectFile::begin_symbols() const {
@@ -205,10 +217,12 @@ void MachOObjectFile::moveToNextSection(DataRefImpl &DRI) const {
  }
 }

-SectionRef MachOObjectFile::getSectionNext(DataRefImpl DRI) const {
+error_code MachOObjectFile::getSectionNext(DataRefImpl DRI,
+                                           SectionRef &Result) const {
  DRI.d.b++;
  moveToNextSection(DRI);
-  return SectionRef(DRI, this);
+  Result = SectionRef(DRI, this);
+  return object_error::success;
 }

 void
@@ -220,43 +234,53 @@ MachOObjectFile::getSection(DataRefImpl DRI,
  MachOObj->ReadSection(LCI, DRI.d.b, Res);
 }

-StringRef MachOObjectFile::getSectionName(DataRefImpl DRI) const {
+error_code MachOObjectFile::getSectionName(DataRefImpl DRI,
+                                           StringRef &Result) const {
  InMemoryStruct<macho::SegmentLoadCommand> SLC;
  LoadCommandInfo LCI = MachOObj->getLoadCommandInfo(DRI.d.a);
  MachOObj->ReadSegmentLoadCommand(LCI, SLC);
  InMemoryStruct<macho::Section> Sect;
  MachOObj->ReadSection(LCI, DRI.d.b, Sect);

-  static char Result[34];
-  strcpy(Result, SLC->Name);
-  strcat(Result, ",");
-  strcat(Result, Sect->Name);
-  return StringRef(Result);
+  static char result[34];
+  strcpy(result, SLC->Name);
+  strcat(result, ",");
+  strcat(result, Sect->Name);
+  Result = StringRef(result);
+  return object_error::success;
 }

-uint64_t MachOObjectFile::getSectionAddress(DataRefImpl DRI) const {
+error_code MachOObjectFile::getSectionAddress(DataRefImpl DRI,
+                                              uint64_t &Result) const {
  InMemoryStruct<macho::Section> Sect;
  getSection(DRI, Sect);
-  return Sect->Address;
+  Result = Sect->Address;
+  return object_error::success;
 }

-uint64_t MachOObjectFile::getSectionSize(DataRefImpl DRI) const {
+error_code MachOObjectFile::getSectionSize(DataRefImpl DRI,
+                                           uint64_t &Result) const {
  InMemoryStruct<macho::Section> Sect;
  getSection(DRI, Sect);
-  return Sect->Size;
+  Result = Sect->Size;
+  return object_error::success;
 }

-StringRef MachOObjectFile::getSectionContents(DataRefImpl DRI) const {
+error_code MachOObjectFile::getSectionContents(DataRefImpl DRI,
+                                               StringRef &Result) const {
  InMemoryStruct<macho::Section> Sect;
  getSection(DRI, Sect);
-  return MachOObj->getData(Sect->Offset, Sect->Size);
+  Result = MachOObj->getData(Sect->Offset, Sect->Size);
+  return object_error::success;
 }

-bool MachOObjectFile::isSectionText(DataRefImpl DRI) const {
+error_code MachOObjectFile::isSectionText(DataRefImpl DRI,
+                                          bool &Result) const {
  InMemoryStruct<macho::SegmentLoadCommand> SLC;
  LoadCommandInfo LCI = MachOObj->getLoadCommandInfo(DRI.d.a);
  MachOObj->ReadSegmentLoadCommand(LCI, SLC);
-  return !strcmp(SLC->Name, "__TEXT");
+  Result = !strcmp(SLC->Name, "__TEXT");
+  return object_error::success;
 }

 ObjectFile::section_iterator MachOObjectFile::begin_sections() const {
--- a/lib/Object/Object.cpp
+++ b/lib/Object/Object.cpp
@@ -41,19 +41,28 @@ LLVMBool LLVMIsSectionIteratorAtEnd(LLVMObjectFileRef ObjectFile,
 }

 void LLVMMoveToNextSection(LLVMSectionIteratorRef SI) {
-  // We can't use unwrap() here because the argument to ++ must be an lvalue.
-  ++*reinterpret_cast<ObjectFile::section_iterator*>(SI);
+  error_code ec;
+  unwrap(SI)->increment(ec);
+  if (ec) report_fatal_error("LLVMMoveToNextSection failed: " + ec.message());
 }

 const char *LLVMGetSectionName(LLVMSectionIteratorRef SI) {
-  return (*unwrap(SI))->getName().data();
+  StringRef ret;
+  if (error_code ec = (*unwrap(SI))->getName(ret))
+   report_fatal_error(ec.message());
+  return ret.data();
 }

 uint64_t LLVMGetSectionSize(LLVMSectionIteratorRef SI) {
-  return (*unwrap(SI))->getSize();
+  uint64_t ret;
+  if (error_code ec = (*unwrap(SI))->getSize(ret))
+    report_fatal_error(ec.message());
+  return ret;
 }

 const char *LLVMGetSectionContents(LLVMSectionIteratorRef SI) {
-  return (*unwrap(SI))->getContents().data();
+  StringRef ret;
+  if (error_code ec = (*unwrap(SI))->getContents(ret))
+    report_fatal_error(ec.message());
+  return ret.data();
 }
-