llvm/lib/Object/Archive.cpp

//===- Archive.cpp - ar File Format 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 ArchiveObjectFile class.
//
//===----------------------------------------------------------------------===//

#include "llvm/Object/Archive.h"
#include "llvm/ADT/APInt.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/Twine.h"
#include "llvm/Support/Endian.h"
#include "llvm/Support/MemoryBuffer.h"

using namespace llvm;
using namespace object;

static const char *const Magic = "!<arch>\n";

void Archive::anchor() { }

StringRef ArchiveMemberHeader::getName() const {
  char EndCond;
  if (Name[0] == '/' || Name[0] == '#')
    EndCond = ' ';
  else
    EndCond = '/';
  llvm::StringRef::size_type end =
      llvm::StringRef(Name, sizeof(Name)).find(EndCond);
  if (end == llvm::StringRef::npos)
    end = sizeof(Name);
  assert(end <= sizeof(Name) && end > 0);
  // Don't include the EndCond if there is one.
  return llvm::StringRef(Name, end);
}

uint32_t ArchiveMemberHeader::getSize() const {
  uint32_t Ret;
  if (llvm::StringRef(Size, sizeof(Size)).rtrim(" ").getAsInteger(10, Ret))
    llvm_unreachable("Size is not a decimal number.");
  return Ret;
}

sys::fs::perms ArchiveMemberHeader::getAccessMode() const {
  unsigned Ret;
  if (StringRef(AccessMode, sizeof(AccessMode)).rtrim(" ").getAsInteger(8, Ret))
    llvm_unreachable("Access mode is not an octal number.");
  return static_cast<sys::fs::perms>(Ret);
}

sys::TimeValue ArchiveMemberHeader::getLastModified() const {
  unsigned Seconds;
  if (StringRef(LastModified, sizeof(LastModified)).rtrim(" ")
          .getAsInteger(10, Seconds))
    llvm_unreachable("Last modified time not a decimal number.");

  sys::TimeValue Ret;
  Ret.fromEpochTime(Seconds);
  return Ret;
}

unsigned ArchiveMemberHeader::getUID() const {
  unsigned Ret;
  if (StringRef(UID, sizeof(UID)).rtrim(" ").getAsInteger(10, Ret))
    llvm_unreachable("UID time not a decimal number.");
  return Ret;
}

unsigned ArchiveMemberHeader::getGID() const {
  unsigned Ret;
  if (StringRef(GID, sizeof(GID)).rtrim(" ").getAsInteger(10, Ret))
    llvm_unreachable("GID time not a decimal number.");
  return Ret;
}

Archive::Child::Child(const Archive *Parent, const char *Start)
    : Parent(Parent) {
  if (!Start)
    return;

  const ArchiveMemberHeader *Header =
      reinterpret_cast<const ArchiveMemberHeader *>(Start);
  Data = StringRef(Start, sizeof(ArchiveMemberHeader) + Header->getSize());

  // Setup StartOfFile and PaddingBytes.
  StartOfFile = sizeof(ArchiveMemberHeader);
  // Don't include attached name.
  StringRef Name = Header->getName();
  if (Name.startswith("#1/")) {
    uint64_t NameSize;
    if (Name.substr(3).rtrim(" ").getAsInteger(10, NameSize))
      llvm_unreachable("Long name length is not an integer");
    StartOfFile += NameSize;
  }
}

Archive::Child Archive::Child::getNext() const {
  size_t SpaceToSkip = Data.size();
  // If it's odd, add 1 to make it even.
  if (SpaceToSkip & 1)
    ++SpaceToSkip;

  const char *NextLoc = Data.data() + SpaceToSkip;

  // Check to see if this is past the end of the archive.
  if (NextLoc >= Parent->Data->getBufferEnd())
    return Child(Parent, nullptr);

  return Child(Parent, NextLoc);
}

ErrorOr<StringRef> Archive::Child::getName() const {
  StringRef name = getRawName();
  // Check if it's a special name.
  if (name[0] == '/') {
    if (name.size() == 1) // Linker member.
      return name;
    if (name.size() == 2 && name[1] == '/') // String table.
      return name;
    // It's a long name.
    // Get the offset.
    std::size_t offset;
    if (name.substr(1).rtrim(" ").getAsInteger(10, offset))
      llvm_unreachable("Long name offset is not an integer");
    const char *addr = Parent->StringTable->Data.begin()
                       + sizeof(ArchiveMemberHeader)
                       + offset;
    // Verify it.
    if (Parent->StringTable == Parent->child_end()
        || addr < (Parent->StringTable->Data.begin()
                   + sizeof(ArchiveMemberHeader))
        || addr > (Parent->StringTable->Data.begin()
                   + sizeof(ArchiveMemberHeader)
                   + Parent->StringTable->getSize()))
      return object_error::parse_failed;

    // GNU long file names end with a /.
    if (Parent->kind() == K_GNU) {
      StringRef::size_type End = StringRef(addr).find('/');
      return StringRef(addr, End);
    }
    return StringRef(addr);
  } else if (name.startswith("#1/")) {
    uint64_t name_size;
    if (name.substr(3).rtrim(" ").getAsInteger(10, name_size))
      llvm_unreachable("Long name length is not an ingeter");
    return Data.substr(sizeof(ArchiveMemberHeader), name_size)
        .rtrim(StringRef("\0", 1));
  }
  // It's a simple name.
  if (name[name.size() - 1] == '/')
    return name.substr(0, name.size() - 1);
  return name;
}

ErrorOr<std::unique_ptr<MemoryBuffer>>
Archive::Child::getMemoryBuffer(bool FullPath) const {
  ErrorOr<StringRef> NameOrErr = getName();
  if (std::error_code EC = NameOrErr.getError())
    return EC;
  StringRef Name = NameOrErr.get();
  SmallString<128> Path;
  std::unique_ptr<MemoryBuffer> Ret(MemoryBuffer::getMemBuffer(
      getBuffer(),
      FullPath
          ? (Twine(Parent->getFileName()) + "(" + Name + ")").toStringRef(Path)
          : Name,
      false));
  return std::move(Ret);
}

ErrorOr<std::unique_ptr<Binary>>
Archive::Child::getAsBinary(LLVMContext *Context) const {
  std::unique_ptr<Binary> ret;
  ErrorOr<std::unique_ptr<MemoryBuffer>> BuffOrErr = getMemoryBuffer();
  if (std::error_code EC = BuffOrErr.getError())
    return EC;

  std::unique_ptr<MemoryBuffer> Buff(BuffOrErr.get().release());
  return createBinary(Buff, Context);
}

ErrorOr<Archive *> Archive::create(std::unique_ptr<MemoryBuffer> Source) {
  std::error_code EC;
  std::unique_ptr<Archive> Ret(new Archive(std::move(Source), EC));
  if (EC)
    return EC;
  return Ret.release();
}

Archive::Archive(std::unique_ptr<MemoryBuffer> Source, std::error_code &ec)
    : Binary(Binary::ID_Archive, std::move(Source)), SymbolTable(child_end()) {
  // Check for sufficient magic.
  if (Data->getBufferSize() < 8 ||
      StringRef(Data->getBufferStart(), 8) != Magic) {
    ec = object_error::invalid_file_type;
    return;
  }

  // Get the special members.
  child_iterator i = child_begin(false);
  child_iterator e = child_end();

  if (i == e) {
    ec = object_error::success;
    return;
  }

  StringRef Name = i->getRawName();

  // Below is the pattern that is used to figure out the archive format
  // GNU archive format
  //  First member : / (may exist, if it exists, points to the symbol table )
  //  Second member : // (may exist, if it exists, points to the string table)
  //  Note : The string table is used if the filename exceeds 15 characters
  // BSD archive format
  //  First member : __.SYMDEF or "__.SYMDEF SORTED" (the symbol table)
  //  There is no string table, if the filename exceeds 15 characters or has a
  //  embedded space, the filename has #1/<size>, The size represents the size
  //  of the filename that needs to be read after the archive header
  // COFF archive format
  //  First member : /
  //  Second member : / (provides a directory of symbols)
  //  Third member : // (may exist, if it exists, contains the string table)
  //  Note: Microsoft PE/COFF Spec 8.3 says that the third member is present
  //  even if the string table is empty. However, lib.exe does not in fact
  //  seem to create the third member if there's no member whose filename
  //  exceeds 15 characters. So the third member is optional.

  if (Name == "__.SYMDEF") {
    Format = K_BSD;
    SymbolTable = i;
    ++i;
    FirstRegular = i;
    ec = object_error::success;
    return;
  }

  if (Name.startswith("#1/")) {
    Format = K_BSD;
    // We know this is BSD, so getName will work since there is no string table.
    ErrorOr<StringRef> NameOrErr = i->getName();
    ec = NameOrErr.getError();
    if (ec)
      return;
    Name = NameOrErr.get();
    if (Name == "__.SYMDEF SORTED") {
      SymbolTable = i;
      ++i;
    }
    FirstRegular = i;
    return;
  }

  if (Name == "/") {
    SymbolTable = i;

    ++i;
    if (i == e) {
      ec = object_error::parse_failed;
      return;
    }
    Name = i->getRawName();
  }

  if (Name == "//") {
    Format = K_GNU;
    StringTable = i;
    ++i;
    FirstRegular = i;
    ec = object_error::success;
    return;
  }

  if (Name[0] != '/') {
    Format = K_GNU;
    FirstRegular = i;
    ec = object_error::success;
    return;
  }

  if (Name != "/") {
    ec = object_error::parse_failed;
    return;
  }

  Format = K_COFF;
  SymbolTable = i;

  ++i;
  if (i == e) {
    FirstRegular = i;
    ec = object_error::success;
    return;
  }

  Name = i->getRawName();

  if (Name == "//") {
    StringTable = i;
    ++i;
  }

  FirstRegular = i;
  ec = object_error::success;
}

Archive::child_iterator Archive::child_begin(bool SkipInternal) const {
  if (Data->getBufferSize() == 8) // empty archive.
    return child_end();

  if (SkipInternal)
    return FirstRegular;

  const char *Loc = Data->getBufferStart() + strlen(Magic);
  Child c(this, Loc);
  return c;
}

Archive::child_iterator Archive::child_end() const {
  return Child(this, nullptr);
}

StringRef Archive::Symbol::getName() const {
  return Parent->SymbolTable->getBuffer().begin() + StringIndex;
}

ErrorOr<Archive::child_iterator> Archive::Symbol::getMember() const {
  const char *Buf = Parent->SymbolTable->getBuffer().begin();
  const char *Offsets = Buf + 4;
  uint32_t Offset = 0;
  if (Parent->kind() == K_GNU) {
    Offset = *(reinterpret_cast<const support::ubig32_t*>(Offsets)
               + SymbolIndex);
  } else if (Parent->kind() == K_BSD) {
    llvm_unreachable("BSD format is not supported");
  } else {
    uint32_t MemberCount = *reinterpret_cast<const support::ulittle32_t*>(Buf);
    
    // Skip offsets.
    Buf += sizeof(support::ulittle32_t)
           + (MemberCount * sizeof(support::ulittle32_t));

    uint32_t SymbolCount = *reinterpret_cast<const support::ulittle32_t*>(Buf);

    if (SymbolIndex >= SymbolCount)
      return object_error::parse_failed;

    // Skip SymbolCount to get to the indices table.
    const char *Indices = Buf + sizeof(support::ulittle32_t);

    // Get the index of the offset in the file member offset table for this
    // symbol.
    uint16_t OffsetIndex =
      *(reinterpret_cast<const support::ulittle16_t*>(Indices)
        + SymbolIndex);
    // Subtract 1 since OffsetIndex is 1 based.
    --OffsetIndex;

    if (OffsetIndex >= MemberCount)
      return object_error::parse_failed;

    Offset = *(reinterpret_cast<const support::ulittle32_t*>(Offsets)
               + OffsetIndex);
  }

  const char *Loc = Parent->getData().begin() + Offset;
  child_iterator Iter(Child(Parent, Loc));
  return Iter;
}

Archive::Symbol Archive::Symbol::getNext() const {
  Symbol t(*this);
  // Go to one past next null.
  t.StringIndex =
      Parent->SymbolTable->getBuffer().find('\0', t.StringIndex) + 1;
  ++t.SymbolIndex;
  return t;
}

Archive::symbol_iterator Archive::symbol_begin() const {
  if (!hasSymbolTable())
    return symbol_iterator(Symbol(this, 0, 0));

  const char *buf = SymbolTable->getBuffer().begin();
  if (kind() == K_GNU) {
    uint32_t symbol_count = 0;
    symbol_count = *reinterpret_cast<const support::ubig32_t*>(buf);
    buf += sizeof(uint32_t) + (symbol_count * (sizeof(uint32_t)));
  } else if (kind() == K_BSD) {
    llvm_unreachable("BSD archive format is not supported");
  } else {
    uint32_t member_count = 0;
    uint32_t symbol_count = 0;
    member_count = *reinterpret_cast<const support::ulittle32_t*>(buf);
    buf += 4 + (member_count * 4); // Skip offsets.
    symbol_count = *reinterpret_cast<const support::ulittle32_t*>(buf);
    buf += 4 + (symbol_count * 2); // Skip indices.
  }
  uint32_t string_start_offset = buf - SymbolTable->getBuffer().begin();
  return symbol_iterator(Symbol(this, 0, string_start_offset));
}

Archive::symbol_iterator Archive::symbol_end() const {
  if (!hasSymbolTable())
    return symbol_iterator(Symbol(this, 0, 0));

  const char *buf = SymbolTable->getBuffer().begin();
  uint32_t symbol_count = 0;
  if (kind() == K_GNU) {
    symbol_count = *reinterpret_cast<const support::ubig32_t*>(buf);
  } else if (kind() == K_BSD) {
    llvm_unreachable("BSD archive format is not supported");
  } else {
    uint32_t member_count = 0;
    member_count = *reinterpret_cast<const support::ulittle32_t*>(buf);
    buf += 4 + (member_count * 4); // Skip offsets.
    symbol_count = *reinterpret_cast<const support::ulittle32_t*>(buf);
  }
  return symbol_iterator(
    Symbol(this, symbol_count, 0));
}

Archive::child_iterator Archive::findSym(StringRef name) const {
  Archive::symbol_iterator bs = symbol_begin();
  Archive::symbol_iterator es = symbol_end();

  for (; bs != es; ++bs) {
    StringRef SymName = bs->getName();
    if (SymName == name) {
      ErrorOr<Archive::child_iterator> ResultOrErr = bs->getMember();
      // FIXME: Should we really eat the error?
      if (ResultOrErr.getError())
        return child_end();
      return ResultOrErr.get();
    }
  }
  return child_end();
}

bool Archive::hasSymbolTable() const {
  return SymbolTable != child_end();
}