//===- lib/ReaderWriter/ELF/ELFLinkingContext.cpp -------------------------===//
//
//                             The LLVM Linker
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

#include "lld/ReaderWriter/ELFLinkingContext.h"

#include "File.h"
#include "TargetHandler.h"
#include "Targets.h"

#include "lld/Core/Instrumentation.h"
#include "lld/Passes/LayoutPass.h"
#include "lld/ReaderWriter/ReaderLinkerScript.h"

#include "llvm/ADT/Triple.h"
#include "llvm/Support/ELF.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/Path.h"

namespace lld {

class CommandLineUndefinedAtom : public SimpleUndefinedAtom {
public:
  CommandLineUndefinedAtom(const File &f, StringRef name)
      : SimpleUndefinedAtom(f, name) {}

  virtual CanBeNull canBeNull() const {
    return CanBeNull::canBeNullAtBuildtime;
  }
};

ELFLinkingContext::ELFLinkingContext(
    llvm::Triple triple, std::unique_ptr<TargetHandlerBase> targetHandler)
    : _outputFileType(elf::ET_EXEC), _triple(triple),
      _targetHandler(std::move(targetHandler)), _baseAddress(0),
      _isStaticExecutable(false), _outputYAML(false), _noInhibitExec(false),
      _mergeCommonStrings(false), _runLayoutPass(true),
      _useShlibUndefines(false), _dynamicLinkerArg(false),
      _noAllowDynamicLibraries(false), _outputMagic(OutputMagic::DEFAULT),
      _sysrootPath("") {}

bool ELFLinkingContext::is64Bits() const { return getTriple().isArch64Bit(); }

bool ELFLinkingContext::isLittleEndian() const {
  // TODO: Do this properly. It is not defined purely by arch.
  return true;
}

void ELFLinkingContext::addPasses(PassManager &pm) const {
  if (_runLayoutPass)
    pm.add(std::unique_ptr<Pass>(new LayoutPass()));
}

uint16_t ELFLinkingContext::getOutputMachine() const {
  switch (getTriple().getArch()) {
  case llvm::Triple::x86:
    return llvm::ELF::EM_386;
  case llvm::Triple::x86_64:
    return llvm::ELF::EM_X86_64;
  case llvm::Triple::hexagon:
    return llvm::ELF::EM_HEXAGON;
  case llvm::Triple::ppc:
    return llvm::ELF::EM_PPC;
  default:
    llvm_unreachable("Unhandled arch");
  }
}

StringRef ELFLinkingContext::entrySymbolName() const {
  if (_outputFileType == elf::ET_EXEC && _entrySymbolName.empty())
    return "_start";
  return _entrySymbolName;
}

bool ELFLinkingContext::validateImpl(raw_ostream &diagnostics) {
  _elfReader = createReaderELF(*this);
  _linkerScriptReader.reset(new ReaderLinkerScript(*this));
  _writer = _outputYAML ? createWriterYAML(*this) : createWriterELF(*this);
  return false;
}

bool ELFLinkingContext::isDynamic() const {
  switch (_outputFileType) {
  case llvm::ELF::ET_EXEC:
    return !_isStaticExecutable;
  case llvm::ELF::ET_DYN:
    return true;
  }
  return false;
}

bool ELFLinkingContext::isRelativeReloc(const Reference &) const {
  return false;
}

error_code ELFLinkingContext::parseFile(LinkerInput &input,
    std::vector<std::unique_ptr<File>> &result) const {
  ScopedTask task(getDefaultDomain(), "parseFile");
  error_code ec = _elfReader->parseFile(input, result);
  if (!ec)
    return ec;

  // Not an ELF file, check file extension to see if it might be yaml
  StringRef path = input.getBuffer().getBufferIdentifier();
  if (path.endswith(".objtxt")) {
    ec = _yamlReader->parseFile(input, result);
    if (!ec)
      return ec;
  }

  // Not a yaml file, assume it is a linkerscript
  return _linkerScriptReader->parseFile(input, result);
}

Writer &ELFLinkingContext::writer() const { return *_writer; }

std::unique_ptr<ELFLinkingContext>
ELFLinkingContext::create(llvm::Triple triple) {
  switch (triple.getArch()) {
  case llvm::Triple::x86:
    return std::unique_ptr<ELFLinkingContext>(
        new lld::elf::X86LinkingContext(triple));
  case llvm::Triple::x86_64:
    return std::unique_ptr<ELFLinkingContext>(
        new lld::elf::X86_64LinkingContext(triple));
  case llvm::Triple::hexagon:
    return std::unique_ptr<ELFLinkingContext>(
        new lld::elf::HexagonLinkingContext(triple));
  case llvm::Triple::ppc:
    return std::unique_ptr<ELFLinkingContext>(
        new lld::elf::PPCLinkingContext(triple));
  default:
    return nullptr;
  }
}

llvm::ErrorOr<std::string> ELFLinkingContext::searchLibrary(
    StringRef libName, const std::vector<StringRef> &searchPath) const {
  bool foundFile = false;
  StringRef pathref;
  for (StringRef dir : searchPath) {
    // Search for dynamic library
    if (!_isStaticExecutable) {
      SmallString<128> dynlibPath;
      if (dir.startswith("=/")) {
        dynlibPath.assign(_sysrootPath);
        dynlibPath.append(dir.substr(1));
      } else {
        dynlibPath.assign(dir);
      }
      llvm::sys::path::append(dynlibPath, Twine("lib") + libName + ".so");
      pathref = dynlibPath.str();
      if (llvm::sys::fs::exists(pathref)) {
        foundFile = true;
      }
    }
    // Search for static libraries too
    if (!foundFile) {
      SmallString<128> archivefullPath;
      if (dir.startswith("=/")) {
        archivefullPath.assign(_sysrootPath);
        archivefullPath.append(dir.substr(1));
      } else {
        archivefullPath.assign(dir);
      }
      llvm::sys::path::append(archivefullPath, Twine("lib") + libName + ".a");
      pathref = archivefullPath.str();
      if (llvm::sys::fs::exists(pathref)) {
        foundFile = true;
      }
    }
    if (foundFile)
      return (*(new (_alloc) std::string(pathref.str())));
  }
  if (!llvm::sys::fs::exists(libName))
    return llvm::make_error_code(llvm::errc::no_such_file_or_directory);

  return std::string(libName);
}

std::unique_ptr<File> ELFLinkingContext::createUndefinedSymbolFile() {
  if (_initialUndefinedSymbols.empty())
    return nullptr;
  std::unique_ptr<SimpleFile> undefinedSymFile(
      new SimpleFile(*this, "command line option -u"));
  for (auto undefSymStr : _initialUndefinedSymbols)
    undefinedSymFile->addAtom(*(new (_allocator) CommandLineUndefinedAtom(
                                   *undefinedSymFile, undefSymStr)));
  return std::move(undefinedSymFile);
}

} // end namespace lld