lib/LD/GNUArchiveReader.cpp

//===- GNUArchiveReader.cpp -----------------------------------------------===//
//
//                     The MCLinker Project
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "mcld/LD/GNUArchiveReader.h"

#include "mcld/InputTree.h"
#include "mcld/LinkerConfig.h"
#include "mcld/Module.h"
#include "mcld/ADT/SizeTraits.h"
#include "mcld/MC/Attribute.h"
#include "mcld/MC/Input.h"
#include "mcld/LD/ELFObjectReader.h"
#include "mcld/LD/ResolveInfo.h"
#include "mcld/Support/FileHandle.h"
#include "mcld/Support/FileSystem.h"
#include "mcld/Support/MemoryArea.h"
#include "mcld/Support/MsgHandling.h"
#include "mcld/Support/Path.h"

#include <llvm/ADT/StringRef.h>
#include <llvm/Support/Host.h>

#include <cstdlib>
#include <cstring>

namespace mcld {

GNUArchiveReader::GNUArchiveReader(Module& pModule,
                                   ELFObjectReader& pELFObjectReader)
    : m_Module(pModule), m_ELFObjectReader(pELFObjectReader) {
}

GNUArchiveReader::~GNUArchiveReader() {
}

/// isMyFormat
bool GNUArchiveReader::isMyFormat(Input& pInput, bool& pContinue) const {
  assert(pInput.hasMemArea());
  if (pInput.memArea()->size() < Archive::MAGIC_LEN)
    return false;

  llvm::StringRef region =
      pInput.memArea()->request(pInput.fileOffset(), Archive::MAGIC_LEN);
  const char* str = region.begin();

  bool result = false;
  assert(str != NULL);
  pContinue = true;
  if (isArchive(str) || isThinArchive(str))
    result = true;

  return result;
}

/// isArchive
bool GNUArchiveReader::isArchive(const char* pStr) const {
  return (memcmp(pStr, Archive::MAGIC, Archive::MAGIC_LEN) == 0);
}

/// isThinArchive
bool GNUArchiveReader::isThinArchive(const char* pStr) const {
  return (memcmp(pStr, Archive::THIN_MAGIC, Archive::MAGIC_LEN) == 0);
}

/// isThinArchive
bool GNUArchiveReader::isThinArchive(Input& pInput) const {
  assert(pInput.hasMemArea());
  llvm::StringRef region =
      pInput.memArea()->request(pInput.fileOffset(), Archive::MAGIC_LEN);
  const char* str = region.begin();

  bool result = false;
  assert(str != NULL);
  if (isThinArchive(str))
    result = true;

  return result;
}

bool GNUArchiveReader::readArchive(const LinkerConfig& pConfig,
                                   Archive& pArchive) {
  // bypass the empty archive
  if (Archive::MAGIC_LEN == pArchive.getARFile().memArea()->size())
    return true;

  if (pArchive.getARFile().attribute()->isWholeArchive())
    return includeAllMembers(pConfig, pArchive);

  // if this is the first time read this archive, setup symtab and strtab
  if (pArchive.getSymbolTable().empty()) {
    // read the symtab of the archive
    readSymbolTable(pArchive);

    // read the strtab of the archive
    readStringTable(pArchive);

    // add root archive to ArchiveMemberMap
    pArchive.addArchiveMember(pArchive.getARFile().name(),
                              pArchive.inputs().root(),
                              &InputTree::Downward);
  }

  // include the needed members in the archive and build up the input tree
  bool willSymResolved;
  do {
    willSymResolved = false;
    for (size_t idx = 0; idx < pArchive.numOfSymbols(); ++idx) {
      // bypass if we already decided to include this symbol or not
      if (Archive::Symbol::Unknown != pArchive.getSymbolStatus(idx))
        continue;

      // bypass if another symbol with the same object file offset is included
      if (pArchive.hasObjectMember(pArchive.getObjFileOffset(idx))) {
        pArchive.setSymbolStatus(idx, Archive::Symbol::Include);
        continue;
      }

      // check if we should include this defined symbol
      Archive::Symbol::Status status =
          shouldIncludeSymbol(pArchive.getSymbolName(idx));
      if (Archive::Symbol::Unknown != status)
        pArchive.setSymbolStatus(idx, status);

      if (Archive::Symbol::Include == status) {
        // include the object member from the given offset
        includeMember(pConfig, pArchive, pArchive.getObjFileOffset(idx));
        willSymResolved = true;
      }  // end of if
    }    // end of for
  } while (willSymResolved);

  return true;
}

/// readMemberHeader - read the header of a member in a archive file and then
/// return the corresponding archive member (it may be an input object or
/// another archive)
/// @param pArchiveRoot  - the archive root that holds the strtab (extended
///                        name table)
/// @param pArchiveFile  - the archive that contains the needed object
/// @param pFileOffset   - file offset of the member header in the archive
/// @param pNestedOffset - used when we find a nested archive
/// @param pMemberSize   - the file size of this member
Input* GNUArchiveReader::readMemberHeader(Archive& pArchiveRoot,
                                          Input& pArchiveFile,
                                          uint32_t pFileOffset,
                                          uint32_t& pNestedOffset,
                                          size_t& pMemberSize) {
  assert(pArchiveFile.hasMemArea());

  llvm::StringRef header_region = pArchiveFile.memArea()->request(
      (pArchiveFile.fileOffset() + pFileOffset), sizeof(Archive::MemberHeader));
  const Archive::MemberHeader* header =
      reinterpret_cast<const Archive::MemberHeader*>(header_region.begin());

  assert(memcmp(header->fmag, Archive::MEMBER_MAGIC, sizeof(header->fmag)) ==
         0);

  pMemberSize = atoi(header->size);

  // parse the member name and nested offset if any
  std::string member_name;
  llvm::StringRef name_field(header->name, sizeof(header->name));
  if (header->name[0] != '/') {
    // this is an object file in an archive
    size_t pos = name_field.find_first_of('/');
    member_name.assign(name_field.substr(0, pos).str());
  } else {
    // this is an object/archive file in a thin archive
    size_t begin = 1;
    size_t end = name_field.find_first_of(" :");
    uint32_t name_offset = 0;
    // parse the name offset
    name_field.substr(begin, end - begin).getAsInteger(10, name_offset);

    if (name_field[end] == ':') {
      // there is a nested offset
      begin = end + 1;
      end = name_field.find_first_of(' ', begin);
      name_field.substr(begin, end - begin).getAsInteger(10, pNestedOffset);
    }

    // get the member name from the extended name table
    assert(pArchiveRoot.hasStrTable());
    begin = name_offset;
    end = pArchiveRoot.getStrTable().find_first_of('\n', begin);
    member_name.assign(
        pArchiveRoot.getStrTable().substr(begin, end - begin - 1));
  }

  Input* member = NULL;
  bool isThinAR = isThinArchive(pArchiveFile);
  if (!isThinAR) {
    // this is an object file in an archive
    member = pArchiveRoot.getMemberFile(
        pArchiveFile,
        isThinAR,
        member_name,
        pArchiveFile.path(),
        (pFileOffset + sizeof(Archive::MemberHeader)));
  } else {
    // this is a member in a thin archive
    // try to find if this is a archive already in the map first
    Archive::ArchiveMember* ar_member =
        pArchiveRoot.getArchiveMember(member_name);
    if (ar_member != NULL) {
      return ar_member->file;
    }

    // get nested file path, the nested file's member name is the relative
    // path to the archive containing it.
    sys::fs::Path input_path(pArchiveFile.path().parent_path());
    if (!input_path.empty())
      input_path.append(sys::fs::Path(member_name));
    else
      input_path.assign(member_name);

    member = pArchiveRoot.getMemberFile(
        pArchiveFile, isThinAR, member_name, input_path);
  }

  return member;
}

template <size_t SIZE>
static void readSymbolTableEntries(Archive& pArchive,
                                   llvm::StringRef pMemRegion) {
  typedef typename SizeTraits<SIZE>::Offset Offset;

  const Offset* data = reinterpret_cast<const Offset*>(pMemRegion.begin());

  // read the number of symbols
  Offset number = 0;
  if (llvm::sys::IsLittleEndianHost)
    number = mcld::bswap<SIZE>(*data);
  else
    number = *data;

  // set up the pointers for file offset and name offset
  ++data;
  const char* name = reinterpret_cast<const char*>(data + number);

  // add the archive symbols
  for (Offset i = 0; i < number; ++i) {
    if (llvm::sys::IsLittleEndianHost)
      pArchive.addSymbol(name, mcld::bswap<SIZE>(*data));
    else
      pArchive.addSymbol(name, *data);
    name += strlen(name) + 1;
    ++data;
  }
}

/// readSymbolTable - read the archive symbol map (armap)
bool GNUArchiveReader::readSymbolTable(Archive& pArchive) {
  assert(pArchive.getARFile().hasMemArea());
  MemoryArea* memory_area = pArchive.getARFile().memArea();

  llvm::StringRef header_region = memory_area->request(
      (pArchive.getARFile().fileOffset() + Archive::MAGIC_LEN),
      sizeof(Archive::MemberHeader));
  const Archive::MemberHeader* header =
      reinterpret_cast<const Archive::MemberHeader*>(header_region.begin());
  assert(memcmp(header->fmag, Archive::MEMBER_MAGIC, sizeof(header->fmag)) ==
         0);

  int symtab_size = atoi(header->size);
  pArchive.setSymTabSize(symtab_size);

  if (!pArchive.getARFile().attribute()->isWholeArchive()) {
    llvm::StringRef symtab_region = memory_area->request(
        (pArchive.getARFile().fileOffset() + Archive::MAGIC_LEN +
         sizeof(Archive::MemberHeader)),
        symtab_size);

    if (strncmp(header->name,
                Archive::SVR4_SYMTAB_NAME,
                strlen(Archive::SVR4_SYMTAB_NAME)) == 0)
      readSymbolTableEntries<32>(pArchive, symtab_region);
    else if (strncmp(header->name,
                     Archive::IRIX6_SYMTAB_NAME,
                     strlen(Archive::IRIX6_SYMTAB_NAME)) == 0)
      readSymbolTableEntries<64>(pArchive, symtab_region);
    else
      unreachable(diag::err_unsupported_archive);
  }
  return true;
}

/// readStringTable - read the strtab for long file name of the archive
bool GNUArchiveReader::readStringTable(Archive& pArchive) {
  size_t offset = Archive::MAGIC_LEN + sizeof(Archive::MemberHeader) +
                  pArchive.getSymTabSize();

  if ((offset & 1) != 0x0)
    ++offset;

  assert(pArchive.getARFile().hasMemArea());
  MemoryArea* memory_area = pArchive.getARFile().memArea();

  llvm::StringRef header_region =
      memory_area->request((pArchive.getARFile().fileOffset() + offset),
                           sizeof(Archive::MemberHeader));
  const Archive::MemberHeader* header =
      reinterpret_cast<const Archive::MemberHeader*>(header_region.begin());

  assert(memcmp(header->fmag, Archive::MEMBER_MAGIC, sizeof(header->fmag)) ==
         0);

  if (memcmp(header->name, Archive::STRTAB_NAME, sizeof(header->name)) == 0) {
    // read the extended name table
    int strtab_size = atoi(header->size);
    llvm::StringRef strtab_region =
        memory_area->request((pArchive.getARFile().fileOffset() + offset +
                              sizeof(Archive::MemberHeader)),
                             strtab_size);
    const char* strtab = strtab_region.begin();
    pArchive.getStrTable().assign(strtab, strtab_size);
  }
  return true;
}

/// shouldIncludeStatus - given a sym name from armap and check if including
/// the corresponding archive member, and then return the decision
enum Archive::Symbol::Status GNUArchiveReader::shouldIncludeSymbol(
    const llvm::StringRef& pSymName) const {
  // TODO: handle symbol version issue and user defined symbols
  const ResolveInfo* info = m_Module.getNamePool().findInfo(pSymName);
  if (info != NULL) {
    if (!info->isUndef())
      return Archive::Symbol::Exclude;
    if (info->isWeak())
      return Archive::Symbol::Unknown;
    return Archive::Symbol::Include;
  }
  return Archive::Symbol::Unknown;
}

/// includeMember - include the object member in the given file offset, and
/// return the size of the object
/// @param pConfig - LinkerConfig
/// @param pArchiveRoot - the archive root
/// @param pFileOffset  - file offset of the member header in the archive
size_t GNUArchiveReader::includeMember(const LinkerConfig& pConfig,
                                       Archive& pArchive,
                                       uint32_t pFileOffset) {
  Input* cur_archive = &(pArchive.getARFile());
  Input* member = NULL;
  uint32_t file_offset = pFileOffset;
  size_t size = 0;
  do {
    uint32_t nested_offset = 0;
    // use the file offset in current archive to find out the member we
    // want to include
    member = readMemberHeader(
        pArchive, *cur_archive, file_offset, nested_offset, size);
    assert(member != NULL);
    // bypass if we get an archive that is already in the map
    if (Input::Archive == member->type()) {
      cur_archive = member;
      file_offset = nested_offset;
      continue;
    }

    // insert a node into the subtree of current archive.
    Archive::ArchiveMember* parent =
        pArchive.getArchiveMember(cur_archive->name());

    assert(parent != NULL);
    pArchive.inputs().insert(parent->lastPos, *(parent->move), *member);

    // move the iterator to new created node, and also adjust the
    // direction to Afterward for next insertion in this subtree
    parent->move->move(parent->lastPos);
    parent->move = &InputTree::Afterward;
    bool doContinue = false;

    if (m_ELFObjectReader.isMyFormat(*member, doContinue)) {
      member->setType(Input::Object);
      // Set this object as no export if the archive is in the exclude libs.
      if (pArchive.getARFile().noExport()) {
        member->setNoExport();
      }
      pArchive.addObjectMember(pFileOffset, parent->lastPos);
      m_ELFObjectReader.readHeader(*member);
      m_ELFObjectReader.readSections(*member);
      m_ELFObjectReader.readSymbols(*member);
      m_Module.getObjectList().push_back(member);
    } else if (doContinue && isMyFormat(*member, doContinue)) {
      member->setType(Input::Archive);
      // when adding a new archive node, set the iterator to archive
      // itself, and set the direction to Downward
      pArchive.addArchiveMember(
          member->name(), parent->lastPos, &InputTree::Downward);
      cur_archive = member;
      file_offset = nested_offset;
    } else {
      warning(diag::warn_unrecognized_input_file)
          << member->path() << pConfig.targets().triple().str();
    }
  } while (Input::Object != member->type());
  return size;
}

/// includeAllMembers - include all object members. This is called if
/// --whole-archive is the attribute for this archive file.
bool GNUArchiveReader::includeAllMembers(const LinkerConfig& pConfig,
                                         Archive& pArchive) {
  // read the symtab of the archive
  readSymbolTable(pArchive);

  // read the strtab of the archive
  readStringTable(pArchive);

  // add root archive to ArchiveMemberMap
  pArchive.addArchiveMember(pArchive.getARFile().name(),
                            pArchive.inputs().root(),
                            &InputTree::Downward);

  bool isThinAR = isThinArchive(pArchive.getARFile());
  uint32_t begin_offset = pArchive.getARFile().fileOffset() +
                          Archive::MAGIC_LEN + sizeof(Archive::MemberHeader) +
                          pArchive.getSymTabSize();
  if (pArchive.hasStrTable()) {
    if ((begin_offset & 1) != 0x0)
      ++begin_offset;
    begin_offset +=
        sizeof(Archive::MemberHeader) + pArchive.getStrTable().size();
  }
  uint32_t end_offset = pArchive.getARFile().memArea()->size();
  for (uint32_t offset = begin_offset; offset < end_offset;
       offset += sizeof(Archive::MemberHeader)) {
    size_t size = includeMember(pConfig, pArchive, offset);

    if (!isThinAR) {
      offset += size;
    }

    if ((offset & 1) != 0x0)
      ++offset;
  }
  return true;
}

}  // namespace mcld