//===--- Hurd.cpp - Hurd ToolChain Implementations --------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

#include "Hurd.h"
#include "CommonArgs.h"
#include "clang/Config/config.h"
#include "clang/Driver/Driver.h"
#include "clang/Driver/Options.h"
#include "llvm/Support/Path.h"
#include "llvm/Support/VirtualFileSystem.h"

using namespace clang::driver;
using namespace clang::driver::toolchains;
using namespace clang;
using namespace llvm::opt;

using tools::addPathIfExists;

/// Get our best guess at the multiarch triple for a target.
///
/// Debian-based systems are starting to use a multiarch setup where they use
/// a target-triple directory in the library and header search paths.
/// Unfortunately, this triple does not align with the vanilla target triple,
/// so we provide a rough mapping here.
static std::string getMultiarchTriple(const Driver &D,
                                      const llvm::Triple &TargetTriple,
                                      StringRef SysRoot) {
  if (TargetTriple.getArch() == llvm::Triple::x86) {
    // We use the existence of '/lib/<triple>' as a directory to detect some
    // common hurd triples that don't quite match the Clang triple for both
    // 32-bit and 64-bit targets. Multiarch fixes its install triples to these
    // regardless of what the actual target triple is.
    if (D.getVFS().exists(SysRoot + "/lib/i386-gnu"))
      return "i386-gnu";
  }

  // For most architectures, just use whatever we have rather than trying to be
  // clever.
  return TargetTriple.str();
}

static StringRef getOSLibDir(const llvm::Triple &Triple, const ArgList &Args) {
  // It happens that only x86 and PPC use the 'lib32' variant of oslibdir, and
  // using that variant while targeting other architectures causes problems
  // because the libraries are laid out in shared system roots that can't cope
  // with a 'lib32' library search path being considered. So we only enable
  // them when we know we may need it.
  //
  // FIXME: This is a bit of a hack. We should really unify this code for
  // reasoning about oslibdir spellings with the lib dir spellings in the
  // GCCInstallationDetector, but that is a more significant refactoring.

  if (Triple.getArch() == llvm::Triple::x86)
    return "lib32";

  return Triple.isArch32Bit() ? "lib" : "lib64";
}

static void addMultilibsFilePaths(const Driver &D, const MultilibSet &Multilibs,
                                  const Multilib &Multilib,
                                  StringRef InstallPath,
                                  ToolChain::path_list &Paths) {
  if (const auto &PathsCallback = Multilibs.filePathsCallback())
    for (const auto &Path : PathsCallback(Multilib))
      addPathIfExists(D, InstallPath + Path, Paths);
}

Hurd::Hurd(const Driver &D, const llvm::Triple &Triple,
           const ArgList &Args)
    : Generic_ELF(D, Triple, Args) {
  GCCInstallation.init(Triple, Args);
  Multilibs = GCCInstallation.getMultilibs();
  SelectedMultilib = GCCInstallation.getMultilib();
  std::string SysRoot = computeSysRoot();

  // Cross-compiling binutils and GCC installations (vanilla and openSUSE at
  // least) put various tools in a triple-prefixed directory off of the parent
  // of the GCC installation. We use the GCC triple here to ensure that we end
  // up with tools that support the same amount of cross compiling as the
  // detected GCC installation. For example, if we find a GCC installation
  // targeting x86_64, but it is a bi-arch GCC installation, it can also be
  // used to target i386.
  // FIXME: This seems unlikely to be Linux- or Hurd-specific.
  ToolChain::path_list &PPaths = getProgramPaths();
  if (GCCInstallation.isValid()) {
    PPaths.push_back(Twine(GCCInstallation.getParentLibPath() + "/../" +
                           GCCInstallation.getTriple().str() + "/bin")
                         .str());
  }

#ifdef ENABLE_LINKER_BUILD_ID
  ExtraOpts.push_back("--build-id");
#endif

  // The selection of paths to try here is designed to match the patterns which
  // the GCC driver itself uses, as this is part of the GCC-compatible driver.
  // This was determined by running GCC in a fake filesystem, creating all
  // possible permutations of these directories, and seeing which ones it added
  // to the link paths.
  path_list &Paths = getFilePaths();

  const std::string OSLibDir = getOSLibDir(Triple, Args);
  const std::string MultiarchTriple = getMultiarchTriple(D, Triple, SysRoot);

  // Add the multilib suffixed paths where they are available.
  if (GCCInstallation.isValid()) {
    const llvm::Triple &GCCTriple = GCCInstallation.getTriple();
    const std::string &LibPath = GCCInstallation.getParentLibPath();

    // Add toolchain / multilib specific file paths.
    addMultilibsFilePaths(D, Multilibs, SelectedMultilib,
                          GCCInstallation.getInstallPath(), Paths);

    // Sourcery CodeBench MIPS toolchain holds some libraries under
    // a biarch-like suffix of the GCC installation.
    addPathIfExists(
        D, GCCInstallation.getInstallPath() + SelectedMultilib.gccSuffix(),
        Paths);

    // GCC cross compiling toolchains will install target libraries which ship
    // as part of the toolchain under <prefix>/<triple>/<libdir> rather than as
    // any part of the GCC installation in
    // <prefix>/<libdir>/gcc/<triple>/<version>. This decision is somewhat
    // debatable, but is the reality today. We need to search this tree even
    // when we have a sysroot somewhere else. It is the responsibility of
    // whomever is doing the cross build targeting a sysroot using a GCC
    // installation that is *not* within the system root to ensure two things:
    //
    //  1) Any DSOs that are linked in from this tree or from the install path
    //     above must be present on the system root and found via an
    //     appropriate rpath.
    //  2) There must not be libraries installed into
    //     <prefix>/<triple>/<libdir> unless they should be preferred over
    //     those within the system root.
    //
    // Note that this matches the GCC behavior. See the below comment for where
    // Clang diverges from GCC's behavior.
    addPathIfExists(D, LibPath + "/../" + GCCTriple.str() + "/lib/../" +
                           OSLibDir + SelectedMultilib.osSuffix(),
                    Paths);

    // If the GCC installation we found is inside of the sysroot, we want to
    // prefer libraries installed in the parent prefix of the GCC installation.
    // It is important to *not* use these paths when the GCC installation is
    // outside of the system root as that can pick up unintended libraries.
    // This usually happens when there is an external cross compiler on the
    // host system, and a more minimal sysroot available that is the target of
    // the cross. Note that GCC does include some of these directories in some
    // configurations but this seems somewhere between questionable and simply
    // a bug.
    if (StringRef(LibPath).startswith(SysRoot)) {
      addPathIfExists(D, LibPath + "/" + MultiarchTriple, Paths);
      addPathIfExists(D, LibPath + "/../" + OSLibDir, Paths);
    }
  }

  // Similar to the logic for GCC above, if we currently running Clang inside
  // of the requested system root, add its parent library paths to
  // those searched.
  // FIXME: It's not clear whether we should use the driver's installed
  // directory ('Dir' below) or the ResourceDir.
  if (StringRef(D.Dir).startswith(SysRoot)) {
    addPathIfExists(D, D.Dir + "/../lib/" + MultiarchTriple, Paths);
    addPathIfExists(D, D.Dir + "/../" + OSLibDir, Paths);
  }

  addPathIfExists(D, SysRoot + "/lib/" + MultiarchTriple, Paths);
  addPathIfExists(D, SysRoot + "/lib/../" + OSLibDir, Paths);

  addPathIfExists(D, SysRoot + "/usr/lib/" + MultiarchTriple, Paths);
  addPathIfExists(D, SysRoot + "/usr/lib/../" + OSLibDir, Paths);

  // Try walking via the GCC triple path in case of biarch or multiarch GCC
  // installations with strange symlinks.
  if (GCCInstallation.isValid()) {
    addPathIfExists(D,
                    SysRoot + "/usr/lib/" + GCCInstallation.getTriple().str() +
                        "/../../" + OSLibDir,
                    Paths);

    // Add the 'other' biarch variant path
    Multilib BiarchSibling;
    if (GCCInstallation.getBiarchSibling(BiarchSibling)) {
      addPathIfExists(D, GCCInstallation.getInstallPath() +
                             BiarchSibling.gccSuffix(),
                      Paths);
    }

    // See comments above on the multilib variant for details of why this is
    // included even from outside the sysroot.
    const std::string &LibPath = GCCInstallation.getParentLibPath();
    const llvm::Triple &GCCTriple = GCCInstallation.getTriple();
    const Multilib &Multilib = GCCInstallation.getMultilib();
    addPathIfExists(D, LibPath + "/../" + GCCTriple.str() + "/lib" +
                           Multilib.osSuffix(),
                    Paths);

    // See comments above on the multilib variant for details of why this is
    // only included from within the sysroot.
    if (StringRef(LibPath).startswith(SysRoot))
      addPathIfExists(D, LibPath, Paths);
  }

  // Similar to the logic for GCC above, if we are currently running Clang
  // inside of the requested system root, add its parent library path to those
  // searched.
  // FIXME: It's not clear whether we should use the driver's installed
  // directory ('Dir' below) or the ResourceDir.
  if (StringRef(D.Dir).startswith(SysRoot))
    addPathIfExists(D, D.Dir + "/../lib", Paths);

  addPathIfExists(D, SysRoot + "/lib", Paths);
  addPathIfExists(D, SysRoot + "/usr/lib", Paths);
}

bool Hurd::HasNativeLLVMSupport() const { return true; }

Tool *Hurd::buildLinker() const { return new tools::gnutools::Linker(*this); }

Tool *Hurd::buildAssembler() const {
  return new tools::gnutools::Assembler(*this);
}

std::string Hurd::computeSysRoot() const {
  if (!getDriver().SysRoot.empty())
    return getDriver().SysRoot;

  return std::string();
}

std::string Hurd::getDynamicLinker(const ArgList &Args) const {
  if (getArch() == llvm::Triple::x86)
    return "/lib/ld.so";

  llvm_unreachable("unsupported architecture");
}

void Hurd::AddClangSystemIncludeArgs(const ArgList &DriverArgs,
                                     ArgStringList &CC1Args) const {
  const Driver &D = getDriver();
  std::string SysRoot = computeSysRoot();

  if (DriverArgs.hasArg(clang::driver::options::OPT_nostdinc))
    return;

  if (!DriverArgs.hasArg(options::OPT_nostdlibinc))
    addSystemInclude(DriverArgs, CC1Args, SysRoot + "/usr/local/include");

  if (!DriverArgs.hasArg(options::OPT_nobuiltininc)) {
    SmallString<128> P(D.ResourceDir);
    llvm::sys::path::append(P, "include");
    addSystemInclude(DriverArgs, CC1Args, P);
  }

  if (DriverArgs.hasArg(options::OPT_nostdlibinc))
    return;

  // Check for configure-time C include directories.
  StringRef CIncludeDirs(C_INCLUDE_DIRS);
  if (CIncludeDirs != "") {
    SmallVector<StringRef, 5> Dirs;
    CIncludeDirs.split(Dirs, ":");
    for (StringRef Dir : Dirs) {
      StringRef Prefix =
          llvm::sys::path::is_absolute(Dir) ? StringRef(SysRoot) : "";
      addExternCSystemInclude(DriverArgs, CC1Args, Prefix + Dir);
    }
    return;
  }

  // Lacking those, try to detect the correct set of system includes for the
  // target triple.

  // Add include directories specific to the selected multilib set and multilib.
  if (GCCInstallation.isValid()) {
    const auto &Callback = Multilibs.includeDirsCallback();
    if (Callback) {
      for (const auto &Path : Callback(GCCInstallation.getMultilib()))
        addExternCSystemIncludeIfExists(
            DriverArgs, CC1Args, GCCInstallation.getInstallPath() + Path);
    }
  }

  if (getTriple().getArch() == llvm::Triple::x86) {
    std::string Path = SysRoot + "/usr/include/i386-gnu";
    if (D.getVFS().exists(Path))
      addExternCSystemInclude(DriverArgs, CC1Args, Path);
  }

  // Add an include of '/include' directly. This isn't provided by default by
  // system GCCs, but is often used with cross-compiling GCCs, and harmless to
  // add even when Clang is acting as-if it were a system compiler.
  addExternCSystemInclude(DriverArgs, CC1Args, SysRoot + "/include");

  addExternCSystemInclude(DriverArgs, CC1Args, SysRoot + "/usr/include");
}

static std::string DetectLibcxxIncludePath(llvm::vfs::FileSystem &vfs,
                                           StringRef base) {
  std::error_code EC;
  int MaxVersion = 0;
  std::string MaxVersionString = "";
  for (llvm::vfs::directory_iterator LI = vfs.dir_begin(base, EC), LE;
       !EC && LI != LE; LI = LI.increment(EC)) {
    StringRef VersionText = llvm::sys::path::filename(LI->path());
    int Version;
    if (VersionText[0] == 'v' &&
        !VersionText.slice(1, StringRef::npos).getAsInteger(10, Version)) {
      if (Version > MaxVersion) {
        MaxVersion = Version;
        MaxVersionString = VersionText;
      }
    }
  }
  return MaxVersion ? (base + "/" + MaxVersionString).str() : "";
}

void Hurd::addLibCxxIncludePaths(const llvm::opt::ArgList &DriverArgs,
                                 llvm::opt::ArgStringList &CC1Args) const {
  const std::string& SysRoot = computeSysRoot();
  const std::string LibCXXIncludePathCandidates[] = {
      DetectLibcxxIncludePath(getVFS(), getDriver().Dir + "/../include/c++"),
      // If this is a development, non-installed, clang, libcxx will
      // not be found at ../include/c++ but it likely to be found at
      // one of the following two locations:
      DetectLibcxxIncludePath(getVFS(), SysRoot + "/usr/local/include/c++"),
      DetectLibcxxIncludePath(getVFS(), SysRoot + "/usr/include/c++") };
  for (const auto &IncludePath : LibCXXIncludePathCandidates) {
    if (IncludePath.empty() || !getVFS().exists(IncludePath))
      continue;
    // Use the first candidate that exists.
    addSystemInclude(DriverArgs, CC1Args, IncludePath);
    return;
  }
}

void Hurd::addLibStdCxxIncludePaths(const llvm::opt::ArgList &DriverArgs,
                                    llvm::opt::ArgStringList &CC1Args) const {
  // We need a detected GCC installation on Hurd to provide libstdc++'s
  // headers.
  if (!GCCInstallation.isValid())
    return;

  // By default, look for the C++ headers in an include directory adjacent to
  // the lib directory of the GCC installation. Note that this is expect to be
  // equivalent to '/usr/include/c++/X.Y' in almost all cases.
  StringRef LibDir = GCCInstallation.getParentLibPath();
  StringRef InstallDir = GCCInstallation.getInstallPath();
  StringRef TripleStr = GCCInstallation.getTriple().str();
  const Multilib &Multilib = GCCInstallation.getMultilib();
  const std::string GCCMultiarchTriple = getMultiarchTriple(
      getDriver(), GCCInstallation.getTriple(), getDriver().SysRoot);
  const std::string TargetMultiarchTriple =
      getMultiarchTriple(getDriver(), getTriple(), getDriver().SysRoot);
  const GCCVersion &Version = GCCInstallation.getVersion();

  // The primary search for libstdc++ supports multiarch variants.
  if (addLibStdCXXIncludePaths(LibDir.str() + "/../include",
                               "/c++/" + Version.Text, TripleStr,
                               GCCMultiarchTriple, TargetMultiarchTriple,
                               Multilib.includeSuffix(), DriverArgs, CC1Args))
    return;

  // Otherwise, fall back on a bunch of options which don't use multiarch
  // layouts for simplicity.
  const std::string LibStdCXXIncludePathCandidates[] = {
      // Gentoo is weird and places its headers inside the GCC install,
      // so if the first attempt to find the headers fails, try these patterns.
      InstallDir.str() + "/include/g++-v" + Version.Text,
      InstallDir.str() + "/include/g++-v" + Version.MajorStr + "." +
          Version.MinorStr,
      InstallDir.str() + "/include/g++-v" + Version.MajorStr,
      // Android standalone toolchain has C++ headers in yet another place.
      LibDir.str() + "/../" + TripleStr.str() + "/include/c++/" + Version.Text,
      // Freescale SDK C++ headers are directly in <sysroot>/usr/include/c++,
      // without a subdirectory corresponding to the gcc version.
      LibDir.str() + "/../include/c++",
  };

  for (const auto &IncludePath : LibStdCXXIncludePathCandidates) {
    if (addLibStdCXXIncludePaths(IncludePath, /*Suffix*/ "", TripleStr,
                                 /*GCCMultiarchTriple*/ "",
                                 /*TargetMultiarchTriple*/ "",
                                 Multilib.includeSuffix(), DriverArgs, CC1Args))
      break;
  }
}