//===- MinGW/Driver.cpp ---------------------------------------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
// MinGW is a GNU development environment for Windows. It consists of GNU
// tools such as GCC and GNU ld. Unlike Cygwin, there's no POSIX-compatible
// layer, as it aims to be a native development toolchain.
//
// lld/MinGW is a drop-in replacement for GNU ld/MinGW.
//
// Being a native development tool, a MinGW linker is not very different from
// Microsoft link.exe, so a MinGW linker can be implemented as a thin wrapper
// for lld/COFF. This driver takes Unix-ish command line options, translates
// them to Windows-ish ones, and then passes them to lld/COFF.
//
// When this driver calls the lld/COFF driver, it passes a hidden option
// "-lldmingw" along with other user-supplied options, to run the lld/COFF
// linker in "MinGW mode".
//
// There are subtle differences between MS link.exe and GNU ld/MinGW, and GNU
// ld/MinGW implements a few GNU-specific features. Such features are directly
// implemented in lld/COFF and enabled only when the linker is running in MinGW
// mode.
//
//===----------------------------------------------------------------------===//

#include "lld/Common/Driver.h"
#include "lld/Common/ErrorHandler.h"
#include "lld/Common/Version.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/Optional.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/Option/Arg.h"
#include "llvm/Option/ArgList.h"
#include "llvm/Option/Option.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/Path.h"

#if !defined(_MSC_VER) && !defined(__MINGW32__)
#include <unistd.h>
#endif

using namespace lld;
using namespace llvm;

// Create OptTable
enum {
  OPT_INVALID = 0,
#define OPTION(_1, _2, ID, _4, _5, _6, _7, _8, _9, _10, _11, _12) OPT_##ID,
#include "Options.inc"
#undef OPTION
};

// Create prefix string literals used in Options.td
#define PREFIX(NAME, VALUE) static const char *const NAME[] = VALUE;
#include "Options.inc"
#undef PREFIX

// Create table mapping all options defined in Options.td
static const opt::OptTable::Info InfoTable[] = {
#define OPTION(X1, X2, ID, KIND, GROUP, ALIAS, X7, X8, X9, X10, X11, X12)      \
  {X1, X2, X10,         X11,         OPT_##ID, opt::Option::KIND##Class,       \
   X9, X8, OPT_##GROUP, OPT_##ALIAS, X7,       X12},
#include "Options.inc"
#undef OPTION
};

namespace {
class MinGWOptTable : public opt::OptTable {
public:
  MinGWOptTable() : OptTable(InfoTable, false) {}
  opt::InputArgList parse(ArrayRef<const char *> Argv);
};
} // namespace

static void printHelp(const char *Argv0) {
  MinGWOptTable().PrintHelp(
      outs(), (std::string(Argv0) + " [options] file...").c_str(), "lld",
      false /*ShowHidden*/, true /*ShowAllAliases*/);
  outs() << "\n";
}

opt::InputArgList MinGWOptTable::parse(ArrayRef<const char *> Argv) {
  unsigned MissingIndex;
  unsigned MissingCount;

  SmallVector<const char *, 256> Vec(Argv.data(), Argv.data() + Argv.size());
  opt::InputArgList Args = this->ParseArgs(Vec, MissingIndex, MissingCount);

  if (MissingCount)
    fatal(StringRef(Args.getArgString(MissingIndex)) + ": missing argument");
  for (auto *Arg : Args.filtered(OPT_UNKNOWN))
    fatal("unknown argument: " + Arg->getSpelling());
  return Args;
}

// Find a file by concatenating given paths.
static Optional<std::string> findFile(StringRef Path1, const Twine &Path2) {
  SmallString<128> S;
  sys::path::append(S, Path1, Path2);
  if (sys::fs::exists(S))
    return S.str().str();
  return None;
}

// This is for -lfoo. We'll look for libfoo.dll.a or libfoo.a from search paths.
static std::string
searchLibrary(StringRef Name, ArrayRef<StringRef> SearchPaths, bool BStatic) {
  if (Name.startswith(":")) {
    for (StringRef Dir : SearchPaths)
      if (Optional<std::string> S = findFile(Dir, Name.substr(1)))
        return *S;
    fatal("unable to find library -l" + Name);
  }

  for (StringRef Dir : SearchPaths) {
    if (!BStatic)
      if (Optional<std::string> S = findFile(Dir, "lib" + Name + ".dll.a"))
        return *S;
    if (Optional<std::string> S = findFile(Dir, "lib" + Name + ".a"))
      return *S;
  }
  fatal("unable to find library -l" + Name);
}

// Convert Unix-ish command line arguments to Windows-ish ones and
// then call coff::link.
bool mingw::link(ArrayRef<const char *> ArgsArr, raw_ostream &Diag) {
  MinGWOptTable Parser;
  opt::InputArgList Args = Parser.parse(ArgsArr.slice(1));

  if (Args.hasArg(OPT_help)) {
    printHelp(ArgsArr[0]);
    return true;
  }

  // A note about "compatible with GNU linkers" message: this is a hack for
  // scripts generated by GNU Libtool 2.4.6 (released in February 2014 and
  // still the newest version in March 2017) or earlier to recognize LLD as
  // a GNU compatible linker. As long as an output for the -v option
  // contains "GNU" or "with BFD", they recognize us as GNU-compatible.
  if (Args.hasArg(OPT_v) || Args.hasArg(OPT_version))
    message(getLLDVersion() + " (compatible with GNU linkers)");

  // The behavior of -v or --version is a bit strange, but this is
  // needed for compatibility with GNU linkers.
  if (Args.hasArg(OPT_v) && !Args.hasArg(OPT_INPUT) && !Args.hasArg(OPT_l))
    return true;
  if (Args.hasArg(OPT_version))
    return true;

  if (!Args.hasArg(OPT_INPUT) && !Args.hasArg(OPT_l))
    fatal("no input files");

  std::vector<std::string> LinkArgs;
  auto Add = [&](const Twine &S) { LinkArgs.push_back(S.str()); };

  Add("lld-link");
  Add("-lldmingw");

  if (auto *A = Args.getLastArg(OPT_entry)) {
    StringRef S = A->getValue();
    if (Args.getLastArgValue(OPT_m) == "i386pe" && S.startswith("_"))
      Add("-entry:" + S.substr(1));
    else
      Add("-entry:" + S);
  }

  if (auto *A = Args.getLastArg(OPT_subs))
    Add("-subsystem:" + StringRef(A->getValue()));
  if (auto *A = Args.getLastArg(OPT_out_implib))
    Add("-implib:" + StringRef(A->getValue()));
  if (auto *A = Args.getLastArg(OPT_stack))
    Add("-stack:" + StringRef(A->getValue()));
  if (auto *A = Args.getLastArg(OPT_output_def))
    Add("-output-def:" + StringRef(A->getValue()));
  if (auto *A = Args.getLastArg(OPT_image_base))
    Add("-base:" + StringRef(A->getValue()));
  if (auto *A = Args.getLastArg(OPT_map))
    Add("-lldmap:" + StringRef(A->getValue()));

  if (auto *A = Args.getLastArg(OPT_o))
    Add("-out:" + StringRef(A->getValue()));
  else if (Args.hasArg(OPT_shared))
    Add("-out:a.dll");
  else
    Add("-out:a.exe");

  if (auto *A = Args.getLastArg(OPT_pdb)) {
    Add("-debug");
    StringRef V = A->getValue();
    if (!V.empty())
      Add("-pdb:" + V);
  } else if (Args.hasArg(OPT_strip_debug)) {
    Add("-debug:symtab");
  } else if (!Args.hasArg(OPT_strip_all)) {
    Add("-debug:dwarf");
  }

  if (Args.hasArg(OPT_shared))
    Add("-dll");
  if (Args.hasArg(OPT_verbose))
    Add("-verbose");
  if (Args.hasArg(OPT_exclude_all_symbols))
    Add("-exclude-all-symbols");
  if (Args.hasArg(OPT_export_all_symbols))
    Add("-export-all-symbols");
  if (Args.hasArg(OPT_large_address_aware))
    Add("-largeaddressaware");
  if (Args.hasArg(OPT_kill_at))
    Add("-kill-at");
  if (Args.hasArg(OPT_appcontainer))
    Add("-appcontainer");

  if (Args.getLastArgValue(OPT_m) != "thumb2pe" &&
      Args.getLastArgValue(OPT_m) != "arm64pe" && !Args.hasArg(OPT_dynamicbase))
    Add("-dynamicbase:no");

  if (Args.hasFlag(OPT_no_insert_timestamp, OPT_insert_timestamp, false))
    Add("-timestamp:0");

  if (Args.hasFlag(OPT_gc_sections, OPT_no_gc_sections, false))
    Add("-opt:ref");
  else
    Add("-opt:noref");

  if (auto *A = Args.getLastArg(OPT_icf)) {
    StringRef S = A->getValue();
    if (S == "all")
      Add("-opt:icf");
    else if (S == "safe" || S == "none")
      Add("-opt:noicf");
    else
      fatal("unknown parameter: --icf=" + S);
  } else {
    Add("-opt:noicf");
  }

  if (auto *A = Args.getLastArg(OPT_m)) {
    StringRef S = A->getValue();
    if (S == "i386pe")
      Add("-machine:x86");
    else if (S == "i386pep")
      Add("-machine:x64");
    else if (S == "thumb2pe")
      Add("-machine:arm");
    else if (S == "arm64pe")
      Add("-machine:arm64");
    else
      fatal("unknown parameter: -m" + S);
  }

  for (auto *A : Args.filtered(OPT_mllvm))
    Add("-mllvm:" + StringRef(A->getValue()));

  for (auto *A : Args.filtered(OPT_Xlink))
    Add(A->getValue());

  if (Args.getLastArgValue(OPT_m) == "i386pe")
    Add("-alternatename:__image_base__=___ImageBase");
  else
    Add("-alternatename:__image_base__=__ImageBase");

  for (auto *A : Args.filtered(OPT_require_defined))
    Add("-include:" + StringRef(A->getValue()));
  for (auto *A : Args.filtered(OPT_undefined))
    Add("-includeoptional:" + StringRef(A->getValue()));

  std::vector<StringRef> SearchPaths;
  for (auto *A : Args.filtered(OPT_L)) {
    SearchPaths.push_back(A->getValue());
    Add("-libpath:" + StringRef(A->getValue()));
  }

  StringRef Prefix = "";
  bool Static = false;
  for (auto *A : Args) {
    switch (A->getOption().getUnaliasedOption().getID()) {
    case OPT_INPUT:
      if (StringRef(A->getValue()).endswith_lower(".def"))
        Add("-def:" + StringRef(A->getValue()));
      else
        Add(Prefix + StringRef(A->getValue()));
      break;
    case OPT_l:
      Add(Prefix + searchLibrary(A->getValue(), SearchPaths, Static));
      break;
    case OPT_whole_archive:
      Prefix = "-wholearchive:";
      break;
    case OPT_no_whole_archive:
      Prefix = "";
      break;
    case OPT_Bstatic:
      Static = true;
      break;
    case OPT_Bdynamic:
      Static = false;
      break;
    }
  }

  if (Args.hasArg(OPT_verbose) || Args.hasArg(OPT__HASH_HASH_HASH))
    outs() << llvm::join(LinkArgs, " ") << "\n";

  if (Args.hasArg(OPT__HASH_HASH_HASH))
    return true;

  // Repack vector of strings to vector of const char pointers for coff::link.
  std::vector<const char *> Vec;
  for (const std::string &S : LinkArgs)
    Vec.push_back(S.c_str());
  return coff::link(Vec, true);
}