C++ SectionRef::getContents方法代码示例

void COFFDumper::printRelocation(const SectionRef &Section,
                                 const RelocationRef &Reloc) {
  uint64_t Offset;
  uint64_t RelocType;
  SmallString<32> RelocName;
  StringRef SymbolName;
  StringRef Contents;
  if (error(Reloc.getOffset(Offset)))
    return;
  if (error(Reloc.getType(RelocType)))
    return;
  if (error(Reloc.getTypeName(RelocName)))
    return;
  symbol_iterator Symbol = Reloc.getSymbol();
  if (error(Symbol->getName(SymbolName)))
    return;
  if (error(Section.getContents(Contents)))
    return;

  if (opts::ExpandRelocs) {
    DictScope Group(W, "Relocation");
    W.printHex("Offset", Offset);
    W.printNumber("Type", RelocName, RelocType);
    W.printString("Symbol", SymbolName.size() > 0 ? SymbolName : "-");
  } else {
    raw_ostream& OS = W.startLine();
    OS << W.hex(Offset)
       << " " << RelocName
       << " " << (SymbolName.size() > 0 ? SymbolName : "-")
       << "\n";
  }
}

void COFFDumper::printCodeViewSection(const SectionRef &Section) {
  StringRef Data;
  error(Section.getContents(Data));

  SmallVector<StringRef, 10> FunctionNames;
  StringMap<StringRef> FunctionLineTables;

  ListScope D(W, "CodeViewDebugInfo");
  {
    // FIXME: Add more offset correctness checks.
    DataExtractor DE(Data, true, 4);
    uint32_t Offset = 0,
             Magic = DE.getU32(&Offset);
    W.printHex("Magic", Magic);
    if (Magic != COFF::DEBUG_SECTION_MAGIC) {
      error(object_error::parse_failed);
      return;
    }

    bool Finished = false;
    while (DE.isValidOffset(Offset) && !Finished) {
      // The section consists of a number of subsection in the following format:
      // |Type|PayloadSize|Payload...|
      uint32_t SubSectionType = DE.getU32(&Offset),
               PayloadSize = DE.getU32(&Offset);
      ListScope S(W, "Subsection");
      W.printHex("Type", SubSectionType);
      W.printHex("PayloadSize", PayloadSize);
      if (PayloadSize > Data.size() - Offset) {
        error(object_error::parse_failed);
        return;
      }

      StringRef Contents = Data.substr(Offset, PayloadSize);
      if (opts::CodeViewSubsectionBytes) {
        // Print the raw contents to simplify debugging if anything goes wrong
        // afterwards.
        W.printBinaryBlock("Contents", Contents);
      }

      switch (SubSectionType) {
      case COFF::DEBUG_SYMBOL_SUBSECTION:
        printCodeViewSymbolsSubsection(Contents, Section, Offset);
        break;
      case COFF::DEBUG_LINE_TABLE_SUBSECTION: {
        // Holds a PC to file:line table.  Some data to parse this subsection is
        // stored in the other subsections, so just check sanity and store the
        // pointers for deferred processing.

        if (PayloadSize < 12) {
          // There should be at least three words to store two function
          // relocations and size of the code.
          error(object_error::parse_failed);
          return;
        }

        StringRef LinkageName;
        error(resolveSymbolName(Obj->getCOFFSection(Section), Offset,
                                LinkageName));
        W.printString("LinkageName", LinkageName);
        if (FunctionLineTables.count(LinkageName) != 0) {
          // Saw debug info for this function already?
          error(object_error::parse_failed);
          return;
        }

        FunctionLineTables[LinkageName] = Contents;
        FunctionNames.push_back(LinkageName);
        break;
      }
      case COFF::DEBUG_STRING_TABLE_SUBSECTION:
        if (PayloadSize == 0 || CVStringTable.data() != nullptr ||
            Contents.back() != '\0') {
          // Empty or duplicate or non-null-terminated subsection.
          error(object_error::parse_failed);
          return;
        }
        CVStringTable = Contents;
        break;
      case COFF::DEBUG_INDEX_SUBSECTION:
        // Holds the translation table from file indices
        // to offsets in the string table.

        if (PayloadSize == 0 ||
            CVFileIndexToStringOffsetTable.data() != nullptr) {
          // Empty or duplicate subsection.
          error(object_error::parse_failed);
          return;
        }
        CVFileIndexToStringOffsetTable = Contents;
        break;
      }
      Offset += PayloadSize;

      // Align the reading pointer by 4.
      Offset += (-Offset) % 4;
    }
  }

  // Dump the line tables now that we've read all the subsections and know all
//.........这里部分代码省略.........

static void
printMachOCompactUnwindSection(const MachOObjectFile *Obj,
                               std::map<uint64_t, SymbolRef> &Symbols,
                               const SectionRef &CompactUnwind) {

  assert(Obj->isLittleEndian() &&
         "There should not be a big-endian .o with __compact_unwind");

  bool Is64 = Obj->is64Bit();
  uint32_t PointerSize = Is64 ? sizeof(uint64_t) : sizeof(uint32_t);
  uint32_t EntrySize = 3 * PointerSize + 2 * sizeof(uint32_t);

  StringRef Contents;
  CompactUnwind.getContents(Contents);

  SmallVector<CompactUnwindEntry, 4> CompactUnwinds;

  // First populate the initial raw offsets, encodings and so on from the entry.
  for (unsigned Offset = 0; Offset < Contents.size(); Offset += EntrySize) {
    CompactUnwindEntry Entry(Contents.data(), Offset, Is64);
    CompactUnwinds.push_back(Entry);
  }

  // Next we need to look at the relocations to find out what objects are
  // actually being referred to.
  for (const RelocationRef &Reloc : CompactUnwind.relocations()) {
    uint64_t RelocAddress;
    Reloc.getOffset(RelocAddress);

    uint32_t EntryIdx = RelocAddress / EntrySize;
    uint32_t OffsetInEntry = RelocAddress - EntryIdx * EntrySize;
    CompactUnwindEntry &Entry = CompactUnwinds[EntryIdx];

    if (OffsetInEntry == 0)
      Entry.FunctionReloc = Reloc;
    else if (OffsetInEntry == PointerSize + 2 * sizeof(uint32_t))
      Entry.PersonalityReloc = Reloc;
    else if (OffsetInEntry == 2 * PointerSize + 2 * sizeof(uint32_t))
      Entry.LSDAReloc = Reloc;
    else
      llvm_unreachable("Unexpected relocation in __compact_unwind section");
  }

  // Finally, we're ready to print the data we've gathered.
  outs() << "Contents of __compact_unwind section:\n";
  for (auto &Entry : CompactUnwinds) {
    outs() << "  Entry at offset "
           << format("0x%" PRIx32, Entry.OffsetInSection) << ":\n";

    // 1. Start of the region this entry applies to.
    outs() << "    start:                "
           << format("0x%" PRIx64, Entry.FunctionAddr) << ' ';
    printUnwindRelocDest(Obj, Symbols, Entry.FunctionReloc,
                         Entry.FunctionAddr);
    outs() << '\n';

    // 2. Length of the region this entry applies to.
    outs() << "    length:               "
           << format("0x%" PRIx32, Entry.Length) << '\n';
    // 3. The 32-bit compact encoding.
    outs() << "    compact encoding:     "
           << format("0x%08" PRIx32, Entry.CompactEncoding) << '\n';

    // 4. The personality function, if present.
    if (Entry.PersonalityReloc.getObjectFile()) {
      outs() << "    personality function: "
             << format("0x%" PRIx64, Entry.PersonalityAddr) << ' ';
      printUnwindRelocDest(Obj, Symbols, Entry.PersonalityReloc,
                           Entry.PersonalityAddr);
      outs() << '\n';
    }

    // 5. This entry's language-specific data area.
    if (Entry.LSDAReloc.getObjectFile()) {
      outs() << "    LSDA:                 "
             << format("0x%" PRIx64, Entry.LSDAAddr) << ' ';
      printUnwindRelocDest(Obj, Symbols, Entry.LSDAReloc, Entry.LSDAAddr);
      outs() << '\n';
    }
  }
}

unsigned RuntimeDyldImpl::emitSection(const SectionRef &Section,
                                      bool IsCode) {

  unsigned StubBufSize = 0,
           StubSize = getMaxStubSize();
  error_code err;
  if (StubSize > 0) {
    for (relocation_iterator i = Section.begin_relocations(),
         e = Section.end_relocations(); i != e; i.increment(err), Check(err))
      StubBufSize += StubSize;
  }
  StringRef data;
  uint64_t Alignment64;
  Check(Section.getContents(data));
  Check(Section.getAlignment(Alignment64));

  unsigned Alignment = (unsigned)Alignment64 & 0xffffffffL;
  bool IsRequired;
  bool IsVirtual;
  bool IsZeroInit;
  uint64_t DataSize;
  Check(Section.isRequiredForExecution(IsRequired));
  Check(Section.isVirtual(IsVirtual));
  Check(Section.isZeroInit(IsZeroInit));
  Check(Section.getSize(DataSize));

  unsigned Allocate;
  unsigned SectionID = Sections.size();
  uint8_t *Addr;
  const char *pData = 0;

  // Some sections, such as debug info, don't need to be loaded for execution.
  // Leave those where they are.
  if (IsRequired) {
    Allocate = DataSize + StubBufSize;
    Addr = IsCode
      ? MemMgr->allocateCodeSection(Allocate, Alignment, SectionID)
      : MemMgr->allocateDataSection(Allocate, Alignment, SectionID);
    if (!Addr)
      report_fatal_error("Unable to allocate section memory!");

    // Virtual sections have no data in the object image, so leave pData = 0
    if (!IsVirtual)
      pData = data.data();

    // Zero-initialize or copy the data from the image
    if (IsZeroInit || IsVirtual)
      memset(Addr, 0, DataSize);
    else
      memcpy(Addr, pData, DataSize);

    DEBUG(dbgs() << "emitSection SectionID: " << SectionID
                 << " obj addr: " << format("%p", pData)
                 << " new addr: " << format("%p", Addr)
                 << " DataSize: " << DataSize
                 << " StubBufSize: " << StubBufSize
                 << " Allocate: " << Allocate
                 << "\n");
  }
  else {
    // Even if we didn't load the section, we need to record an entry for it
    //   to handle later processing (and by 'handle' I mean don't do anything
    //   with these sections).
    Allocate = 0;
    Addr = 0;
    DEBUG(dbgs() << "emitSection SectionID: " << SectionID
                 << " obj addr: " << format("%p", data.data())
                 << " new addr: 0"
                 << " DataSize: " << DataSize
                 << " StubBufSize: " << StubBufSize
                 << " Allocate: " << Allocate
                 << "\n");
  }

  Sections.push_back(SectionEntry(Addr, Allocate, DataSize,(uintptr_t)pData));
  return SectionID;
}

static void
printMachOUnwindInfoSection(const MachOObjectFile *Obj,
                            std::map<uint64_t, SymbolRef> &Symbols,
                            const SectionRef &UnwindInfo) {

  assert(Obj->isLittleEndian() &&
         "There should not be a big-endian .o with __unwind_info");

  outs() << "Contents of __unwind_info section:\n";

  StringRef Contents;
  UnwindInfo.getContents(Contents);
  const char *Pos = Contents.data();

  //===----------------------------------
  // Section header
  //===----------------------------------

  uint32_t Version = readNext<uint32_t>(Pos);
  outs() << "  Version:                                   "
         << format("0x%" PRIx32, Version) << '\n';
  assert(Version == 1 && "only understand version 1");

  uint32_t CommonEncodingsStart = readNext<uint32_t>(Pos);
  outs() << "  Common encodings array section offset:     "
         << format("0x%" PRIx32, CommonEncodingsStart) << '\n';
  uint32_t NumCommonEncodings = readNext<uint32_t>(Pos);
  outs() << "  Number of common encodings in array:       "
         << format("0x%" PRIx32, NumCommonEncodings) << '\n';

  uint32_t PersonalitiesStart = readNext<uint32_t>(Pos);
  outs() << "  Personality function array section offset: "
         << format("0x%" PRIx32, PersonalitiesStart) << '\n';
  uint32_t NumPersonalities = readNext<uint32_t>(Pos);
  outs() << "  Number of personality functions in array:  "
         << format("0x%" PRIx32, NumPersonalities) << '\n';

  uint32_t IndicesStart = readNext<uint32_t>(Pos);
  outs() << "  Index array section offset:                "
         << format("0x%" PRIx32, IndicesStart) << '\n';
  uint32_t NumIndices = readNext<uint32_t>(Pos);
  outs() << "  Number of indices in array:                "
         << format("0x%" PRIx32, NumIndices) << '\n';

  //===----------------------------------
  // A shared list of common encodings
  //===----------------------------------

  // These occupy indices in the range [0, N] whenever an encoding is referenced
  // from a compressed 2nd level index table. In practice the linker only
  // creates ~128 of these, so that indices are available to embed encodings in
  // the 2nd level index.

  SmallVector<uint32_t, 64> CommonEncodings;
  outs() << "  Common encodings: (count = " << NumCommonEncodings << ")\n";
  Pos = Contents.data() + CommonEncodingsStart;
  for (unsigned i = 0; i < NumCommonEncodings; ++i) {
    uint32_t Encoding = readNext<uint32_t>(Pos);
    CommonEncodings.push_back(Encoding);

    outs() << "    encoding[" << i << "]: " << format("0x%08" PRIx32, Encoding)
           << '\n';
  }


  //===----------------------------------
  // Personality functions used in this executable
  //===----------------------------------

  // There should be only a handful of these (one per source language,
  // roughly). Particularly since they only get 2 bits in the compact encoding.

  outs() << "  Personality functions: (count = " << NumPersonalities << ")\n";
  Pos = Contents.data() + PersonalitiesStart;
  for (unsigned i = 0; i < NumPersonalities; ++i) {
    uint32_t PersonalityFn = readNext<uint32_t>(Pos);
    outs() << "    personality[" << i + 1
           << "]: " << format("0x%08" PRIx32, PersonalityFn) << '\n';
  }

  //===----------------------------------
  // The level 1 index entries
  //===----------------------------------

  // These specify an approximate place to start searching for the more detailed
  // information, sorted by PC.

  struct IndexEntry {
    uint32_t FunctionOffset;
    uint32_t SecondLevelPageStart;
    uint32_t LSDAStart;
  };

  SmallVector<IndexEntry, 4> IndexEntries;

  outs() << "  Top level indices: (count = " << NumIndices << ")\n";
  Pos = Contents.data() + IndicesStart;
  for (unsigned i = 0; i < NumIndices; ++i) {
    IndexEntry Entry;

//.........这里部分代码省略.........

unsigned RuntimeDyldImpl::emitSection(ObjectImage &Obj,
                                      const SectionRef &Section,
                                      bool IsCode) {

  unsigned StubBufSize = 0,
           StubSize = getMaxStubSize();
  error_code err;
  const ObjectFile *ObjFile = Obj.getObjectFile();
  // FIXME: this is an inefficient way to handle this. We should computed the
  // necessary section allocation size in loadObject by walking all the sections
  // once.
  if (StubSize > 0) {
    for (section_iterator SI = ObjFile->begin_sections(),
           SE = ObjFile->end_sections();
         SI != SE; SI.increment(err), Check(err)) {
      section_iterator RelSecI = SI->getRelocatedSection();
      if (!(RelSecI == Section))
        continue;

      for (relocation_iterator I = SI->begin_relocations(),
             E = SI->end_relocations(); I != E; I.increment(err), Check(err)) {
        StubBufSize += StubSize;
      }
    }
  }

  StringRef data;
  uint64_t Alignment64;
  Check(Section.getContents(data));
  Check(Section.getAlignment(Alignment64));

  unsigned Alignment = (unsigned)Alignment64 & 0xffffffffL;
  bool IsRequired;
  bool IsVirtual;
  bool IsZeroInit;
  bool IsReadOnly;
  uint64_t DataSize;
  StringRef Name;
  Check(Section.isRequiredForExecution(IsRequired));
  Check(Section.isVirtual(IsVirtual));
  Check(Section.isZeroInit(IsZeroInit));
  Check(Section.isReadOnlyData(IsReadOnly));
  Check(Section.getSize(DataSize));
  Check(Section.getName(Name));
  if (StubSize > 0) {
    unsigned StubAlignment = getStubAlignment();
    unsigned EndAlignment = (DataSize | Alignment) & -(DataSize | Alignment);
    if (StubAlignment > EndAlignment)
      StubBufSize += StubAlignment - EndAlignment;
  }

  unsigned Allocate;
  unsigned SectionID = Sections.size();
  uint8_t *Addr;
  const char *pData = 0;

  // Some sections, such as debug info, don't need to be loaded for execution.
  // Leave those where they are.
  if (IsRequired) {
    Allocate = DataSize + StubBufSize;
    Addr = IsCode
      ? MemMgr->allocateCodeSection(Allocate, Alignment, SectionID)
      : MemMgr->allocateDataSection(Allocate, Alignment, SectionID, IsReadOnly);
    if (!Addr)
      report_fatal_error("Unable to allocate section memory!");

    // Virtual sections have no data in the object image, so leave pData = 0
    if (!IsVirtual)
      pData = data.data();

    // Zero-initialize or copy the data from the image
    if (IsZeroInit || IsVirtual)
      memset(Addr, 0, DataSize);
    else
      memcpy(Addr, pData, DataSize);

    DEBUG(dbgs() << "emitSection SectionID: " << SectionID
                 << " Name: " << Name
                 << " obj addr: " << format("%p", pData)
                 << " new addr: " << format("%p", Addr)
                 << " DataSize: " << DataSize
                 << " StubBufSize: " << StubBufSize
                 << " Allocate: " << Allocate
                 << "\n");
    Obj.updateSectionAddress(Section, (uint64_t)Addr);
  }
  else {
    // Even if we didn't load the section, we need to record an entry for it
    // to handle later processing (and by 'handle' I mean don't do anything
    // with these sections).
    Allocate = 0;
    Addr = 0;
    DEBUG(dbgs() << "emitSection SectionID: " << SectionID
                 << " Name: " << Name
                 << " obj addr: " << format("%p", data.data())
                 << " new addr: 0"
                 << " DataSize: " << DataSize
                 << " StubBufSize: " << StubBufSize
                 << " Allocate: " << Allocate
                 << "\n");
//.........这里部分代码省略.........

unsigned RuntimeDyldImpl::emitSection(ObjectImage &Obj,
                                      const SectionRef &Section, bool IsCode) {

  StringRef data;
  uint64_t Alignment64;
  Check(Section.getContents(data));
  Check(Section.getAlignment(Alignment64));

  unsigned Alignment = (unsigned)Alignment64 & 0xffffffffL;
  bool IsRequired;
  bool IsVirtual;
  bool IsZeroInit;
  bool IsReadOnly;
  uint64_t DataSize;
  unsigned PaddingSize = 0;
  unsigned StubBufSize = 0;
  StringRef Name;
  Check(Section.isRequiredForExecution(IsRequired));
  Check(Section.isVirtual(IsVirtual));
  Check(Section.isZeroInit(IsZeroInit));
  Check(Section.isReadOnlyData(IsReadOnly));
  Check(Section.getSize(DataSize));
  Check(Section.getName(Name));

  StubBufSize = computeSectionStubBufSize(Obj, Section);

  // The .eh_frame section (at least on Linux) needs an extra four bytes padded
  // with zeroes added at the end.  For MachO objects, this section has a
  // slightly different name, so this won't have any effect for MachO objects.
  if (Name == ".eh_frame")
    PaddingSize = 4;

  uintptr_t Allocate;
  unsigned SectionID = Sections.size();
  uint8_t *Addr;
  const char *pData = 0;

  // Some sections, such as debug info, don't need to be loaded for execution.
  // Leave those where they are.
  if (IsRequired) {
    Allocate = DataSize + PaddingSize + StubBufSize;
    Addr = IsCode ? MemMgr->allocateCodeSection(Allocate, Alignment, SectionID,
                                                Name)
                  : MemMgr->allocateDataSection(Allocate, Alignment, SectionID,
                                                Name, IsReadOnly);
    if (!Addr)
      report_fatal_error("Unable to allocate section memory!");

    // Virtual sections have no data in the object image, so leave pData = 0
    if (!IsVirtual)
      pData = data.data();

    // Zero-initialize or copy the data from the image
    if (IsZeroInit || IsVirtual)
      memset(Addr, 0, DataSize);
    else
      memcpy(Addr, pData, DataSize);

    // Fill in any extra bytes we allocated for padding
    if (PaddingSize != 0) {
      memset(Addr + DataSize, 0, PaddingSize);
      // Update the DataSize variable so that the stub offset is set correctly.
      DataSize += PaddingSize;
    }

    DEBUG(dbgs() << "emitSection SectionID: " << SectionID << " Name: " << Name
                 << " obj addr: " << format("%p", pData)
                 << " new addr: " << format("%p", Addr)
                 << " DataSize: " << DataSize << " StubBufSize: " << StubBufSize
                 << " Allocate: " << Allocate << "\n");
    Obj.updateSectionAddress(Section, (uint64_t)Addr);
  } else {
    // Even if we didn't load the section, we need to record an entry for it
    // to handle later processing (and by 'handle' I mean don't do anything
    // with these sections).
    Allocate = 0;
    Addr = 0;
    DEBUG(dbgs() << "emitSection SectionID: " << SectionID << " Name: " << Name
                 << " obj addr: " << format("%p", data.data()) << " new addr: 0"
                 << " DataSize: " << DataSize << " StubBufSize: " << StubBufSize
                 << " Allocate: " << Allocate << "\n");
  }

  Sections.push_back(SectionEntry(Name, Addr, DataSize, (uintptr_t)pData));
  return SectionID;
}