llvm-project/lld/lib/Driver/WinLinkDriver.cpp

//===- lib/Driver/WinLinkDriver.cpp ---------------------------------------===//
//
//                             The LLVM Linker
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
///
/// \file
///
/// Concrete instance of the Driver for Windows link.exe.
///
//===----------------------------------------------------------------------===//

#include <cstdlib>
#include <sstream>
#include <map>

#include "lld/Driver/Driver.h"
#include "lld/Driver/WinLinkInputGraph.h"
#include "lld/ReaderWriter/PECOFFLinkingContext.h"

#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/StringSwitch.h"
#include "llvm/Option/Arg.h"
#include "llvm/Option/Option.h"
#include "llvm/Support/Path.h"

namespace lld {

namespace {

// Create enum with OPT_xxx values for each option in WinLinkOptions.td
enum {
  OPT_INVALID = 0,
#define OPTION(PREFIX, NAME, ID, KIND, GROUP, ALIAS, ALIASARGS, FLAGS, PARAM, \
               HELP, META) \
          OPT_##ID,
#include "WinLinkOptions.inc"
#undef OPTION
};

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

// Create table mapping all options defined in WinLinkOptions.td
static const llvm::opt::OptTable::Info infoTable[] = {
#define OPTION(PREFIX, NAME, ID, KIND, GROUP, ALIAS, ALIASARGS, FLAGS, PARAM, \
               HELPTEXT, METAVAR)   \
  { PREFIX, NAME, HELPTEXT, METAVAR, OPT_##ID, llvm::opt::Option::KIND##Class, \
    PARAM, FLAGS, OPT_##GROUP, OPT_##ALIAS, ALIASARGS },
#include "WinLinkOptions.inc"
#undef OPTION
};

// Create OptTable class for parsing actual command line arguments
class WinLinkOptTable : public llvm::opt::OptTable {
public:
  // link.exe's command line options are case insensitive, unlike
  // other driver's options for Unix.
  WinLinkOptTable()
      : OptTable(infoTable, llvm::array_lengthof(infoTable),
                 /* ignoreCase */ true) {}
};

// Split the given string with spaces.
std::vector<std::string> splitArgList(std::string str) {
  std::stringstream stream(str);
  std::istream_iterator<std::string> begin(stream);
  std::istream_iterator<std::string> end;
  return std::vector<std::string>(begin, end);
}

// Split the given string with the path separator.
std::vector<StringRef> splitPathList(StringRef str) {
  std::vector<StringRef> ret;
  while (!str.empty()) {
    StringRef path;
    llvm::tie(path, str) = str.split(';');
    ret.push_back(path);
  }
  return std::move(ret);
}

// Parse an argument for /base, /stack or /heap. The expected string
// is "<integer>[,<integer>]".
bool parseMemoryOption(StringRef arg, uint64_t &reserve, uint64_t &commit) {
  StringRef reserveStr, commitStr;
  llvm::tie(reserveStr, commitStr) = arg.split(',');
  if (reserveStr.getAsInteger(0, reserve))
    return true;
  if (!commitStr.empty() && (commitStr.getAsInteger(0, commit)))
    return true;
  return false;
}

// Returns subsystem type for the given string.
llvm::COFF::WindowsSubsystem stringToWinSubsystem(StringRef str) {
  return llvm::StringSwitch<llvm::COFF::WindowsSubsystem>(str.lower())
      .Case("windows", llvm::COFF::IMAGE_SUBSYSTEM_WINDOWS_GUI)
      .Case("console", llvm::COFF::IMAGE_SUBSYSTEM_WINDOWS_CUI)
      .Case("boot_application",
            llvm::COFF::IMAGE_SUBSYSTEM_WINDOWS_BOOT_APPLICATION)
      .Case("efi_application", llvm::COFF::IMAGE_SUBSYSTEM_EFI_APPLICATION)
      .Case("efi_boot_service_driver",
            llvm::COFF::IMAGE_SUBSYSTEM_EFI_BOOT_SERVICE_DRIVER)
      .Case("efi_rom", llvm::COFF::IMAGE_SUBSYSTEM_EFI_ROM)
      .Case("efi_runtime_driver",
            llvm::COFF::IMAGE_SUBSYSTEM_EFI_RUNTIME_DRIVER)
      .Case("native", llvm::COFF::IMAGE_SUBSYSTEM_NATIVE)
      .Case("posix", llvm::COFF::IMAGE_SUBSYSTEM_POSIX_CUI)
      .Default(llvm::COFF::IMAGE_SUBSYSTEM_UNKNOWN);
}

// Handle /failifmatch option.
bool handleFailIfMismatchOption(StringRef option,
                                std::map<StringRef, StringRef> &mustMatch,
                                raw_ostream &diagnostics) {
  StringRef key, value;
  llvm::tie(key, value) = option.split('=');
  if (key.empty() || value.empty()) {
    diagnostics << "error: malformed /failifmatch option: " << option << "\n";
    return true;
  }
  auto it = mustMatch.find(key);
  if (it != mustMatch.end() && it->second != value) {
    diagnostics << "error: mismatch detected: '" << it->second << "' and '"
                << value << "' for key '" << key << "'\n";
    return true;
  }
  mustMatch[key] = value;
  return false;
}

// Process "LINK" environment variable. If defined, the value of the variable
// should be processed as command line arguments.
std::vector<const char *> processLinkEnv(PECOFFLinkingContext &context,
                                         int argc, const char **argv) {
  std::vector<const char *> ret;
  // The first argument is the name of the command. This should stay at the head
  // of the argument list.
  assert(argc > 0);
  ret.push_back(argv[0]);

  // Add arguments specified by the LINK environment variable.
  if (char *envp = ::getenv("LINK"))
    for (std::string &arg : splitArgList(envp))
      ret.push_back(context.allocateString(arg).data());

  // Add the rest of arguments passed via the command line.
  for (int i = 1; i < argc; ++i)
    ret.push_back(argv[i]);
  ret.push_back(nullptr);
  return std::move(ret);
}

// Process "LIB" environment variable. The variable contains a list of search
// paths separated by semicolons.
void processLibEnv(PECOFFLinkingContext &context) {
  if (char *envp = ::getenv("LIB"))
    for (StringRef path : splitPathList(envp))
      context.appendInputSearchPath(context.allocateString(path));
}

// Returns a default entry point symbol name depending on context image type and
// subsystem. These default names are MS CRT compliant.
StringRef getDefaultEntrySymbolName(PECOFFLinkingContext &context) {
  if (context.getImageType() == PECOFFLinkingContext::ImageType::IMAGE_DLL)
    return "__DllMainCRTStartup";
  llvm::COFF::WindowsSubsystem subsystem = context.getSubsystem();
  if (subsystem == llvm::COFF::WindowsSubsystem::IMAGE_SUBSYSTEM_WINDOWS_GUI)
    return "_WinMainCRTStartup";
  if (subsystem == llvm::COFF::WindowsSubsystem::IMAGE_SUBSYSTEM_WINDOWS_CUI)
    return "_mainCRTStartup";
  return "";
}

// Parses the given command line options and returns the result. Returns NULL if
// there's an error in the options.
std::unique_ptr<llvm::opt::InputArgList>
parseArgs(int argc, const char *argv[], raw_ostream &diagnostics,
          bool isDirective) {
  // Parse command line options using WinLinkOptions.td
  std::unique_ptr<llvm::opt::InputArgList> parsedArgs;
  WinLinkOptTable table;
  unsigned missingIndex;
  unsigned missingCount;
  parsedArgs.reset(table.ParseArgs(&argv[1], &argv[argc],
                                   missingIndex, missingCount));
  if (missingCount) {
    diagnostics << "error: missing arg value for '"
                << parsedArgs->getArgString(missingIndex) << "' expected "
                << missingCount << " argument(s).\n";
    return nullptr;
  }

  // Show warning for unknown arguments. In .drectve section, unknown options
  // starting with "-?" are silently ignored. This is a COFF's feature to embed a
  // new linker option to an object file while keeping backward compatibility.
  for (auto it = parsedArgs->filtered_begin(OPT_UNKNOWN),
            ie = parsedArgs->filtered_end(); it != ie; ++it) {
    StringRef arg = (*it)->getAsString(*parsedArgs);
    if (isDirective && arg.startswith("-?"))
      continue;
    diagnostics << "warning: ignoring unknown argument: " << arg << "\n";
  }
  return parsedArgs;
}

} // namespace

llvm::ErrorOr<StringRef> PECOFFFileNode::path(const LinkingContext &) const {
  if (_path.endswith(".lib"))
    return _ctx.searchLibraryFile(_path);
  if (llvm::sys::path::extension(_path).empty())
    return (_ctx.allocateString(_path.str() + ".obj"));
  return _path;
}

llvm::ErrorOr<StringRef> PECOFFLibraryNode::path(const LinkingContext &) const {
  if (!_path.endswith(".lib"))
    return _ctx.searchLibraryFile(_ctx.allocateString(_path.str() + ".lib"));
  return _ctx.searchLibraryFile(_path);
}

bool WinLinkDriver::linkPECOFF(int argc, const char *argv[],
                               raw_ostream &diagnostics) {
  PECOFFLinkingContext context;
  std::vector<const char *> newargv = processLinkEnv(context, argc, argv);
  processLibEnv(context);
  if (parse(newargv.size() - 1, &newargv[0], context, diagnostics))
    return true;
  return link(context, diagnostics);
}

bool WinLinkDriver::parse(int argc, const char *argv[], PECOFFLinkingContext &ctx,
                          raw_ostream &diagnostics, bool isDirective) {
  std::map<StringRef, StringRef> failIfMismatchMap;
  // Parse the options.
  std::unique_ptr<llvm::opt::InputArgList> parsedArgs = parseArgs(
      argc, argv, diagnostics, isDirective);
  if (!parsedArgs)
    return true;

  if (!ctx.hasInputGraph())
    ctx.setInputGraph(std::unique_ptr<InputGraph>(new InputGraph()));

  InputGraph &inputGraph = ctx.inputGraph();

  // handle /help
  if (parsedArgs->getLastArg(OPT_help)) {
    WinLinkOptTable table;
    table.PrintHelp(llvm::outs(), argv[0], "LLVM Linker", false);
    return true;
  }

  // handle /defaultlib
  std::vector<StringRef> defaultLibs;
  for (llvm::opt::arg_iterator it = parsedArgs->filtered_begin(OPT_defaultlib),
                               ie = parsedArgs->filtered_end();
       it != ie; ++it) {
    defaultLibs.push_back((*it)->getValue());
  }

  // Process all the arguments and create Input Elements
  for (auto inputArg : *parsedArgs) {
    switch (inputArg->getOption().getID()) {
    case OPT_mllvm:
      ctx.appendLLVMOption(inputArg->getValue());
      break;

    case OPT_base:
      // Parse /base command line option. The argument for the parameter is in
      // the
      // form of "<address>[:<size>]".
      uint64_t addr, size;
      // Size should be set to SizeOfImage field in the COFF header, and if
      // it's smaller than the actual size, the linker should warn about that.
      // Currently we just ignore the value of size parameter.
      if (parseMemoryOption(inputArg->getValue(), addr, size))
        return true;
      ctx.setBaseAddress(addr);
      break;
    case OPT_stack: {
      // Parse /stack command line option
      uint64_t reserve;
      uint64_t commit = ctx.getStackCommit();
      if (parseMemoryOption(inputArg->getValue(), reserve, commit))
        return true;
      ctx.setStackReserve(reserve);
      ctx.setStackCommit(commit);
      break;
    }
    case OPT_heap: {
      // Parse /heap command line option
      uint64_t reserve;
      uint64_t commit = ctx.getHeapCommit();
      if (parseMemoryOption(inputArg->getValue(), reserve, commit))
        return true;
      ctx.setHeapReserve(reserve);
      ctx.setHeapCommit(commit);
      break;
    }
    case OPT_machine: {
      StringRef platform = inputArg->getValue();
      if (!platform.equals_lower("x64")) {
        diagnostics << "error: LLD does not support non-x64 platform, "
                    << "but got /machine:" << platform << "\n";
        return true;
      }
      break;
    }
    case OPT_subsystem: {
      // Parse /subsystem command line option. The form of /subsystem is
      // "subsystem_name[,majorOSVersion[.minorOSVersion]]".
      StringRef subsystemStr, osVersion;
      llvm::tie(subsystemStr, osVersion) =
          StringRef(inputArg->getValue()).split(',');
      if (!osVersion.empty()) {
        StringRef majorVersion, minorVersion;
        llvm::tie(majorVersion, minorVersion) = osVersion.split('.');
        if (minorVersion.empty())
          minorVersion = "0";
        int32_t major, minor;
        if (majorVersion.getAsInteger(0, major))
          return true;
        if (minorVersion.getAsInteger(0, minor))
          return true;
        ctx.setMinOSVersion(PECOFFLinkingContext::OSVersion(major, minor));
      }
      // Parse subsystem name.
      llvm::COFF::WindowsSubsystem subsystem =
          stringToWinSubsystem(subsystemStr);
      if (subsystem == llvm::COFF::IMAGE_SUBSYSTEM_UNKNOWN) {
        diagnostics << "error: unknown subsystem name: " << subsystemStr
                    << "\n";
        return true;
      }
      ctx.setSubsystem(subsystem);
      break;
    }

    case OPT_failifmismatch:
      if (handleFailIfMismatchOption(inputArg->getValue(), failIfMismatchMap,
                                     diagnostics))
        return true;
      break;

    case OPT_entry:
      // handle /entry
      ctx.setEntrySymbolName(inputArg->getValue());
      break;

    case OPT_libpath:
      // handle /libpath
      ctx.appendInputSearchPath(inputArg->getValue());
      break;

    case OPT_force:
    case OPT_force_unresolved:
      // handle /force or /force:unresolved. We do not currently support
      // /force:multiple.
      ctx.setAllowRemainingUndefines(true);
      break;

    case OPT_no_ref:
      // Handle /opt:noref
      ctx.setDeadStripping(false);
      break;

    case OPT_no_nxcompat:
      // handle /nxcompat:no
      ctx.setNxCompat(false);
      break;

    case OPT_largeaddressaware:
      // handle /largeaddressaware
      ctx.setLargeAddressAware(true);
      break;

    case OPT_fixed:
      // handle /fixed

      // make sure /dynamicbase wasn't specified
      if (parsedArgs->getLastArg(OPT_dynamicbase)) {
        diagnostics << "/dynamicbase must not be specified with /fixed\n";
        return true;
      }

      ctx.setBaseRelocationEnabled(false);
      ctx.setDynamicBaseEnabled(false);
      break;

    case OPT_no_dynamicbase:
      // handle /dynamicbase:no
      ctx.setDynamicBaseEnabled(false);
      break;

    case OPT_tsaware:
      // handle /tsaware
      ctx.setTerminalServerAware(true);
      break;

    case OPT_no_tsaware:
      // handle /tsaware:no
      ctx.setTerminalServerAware(false);
      break;

    case OPT_incl:
      // handle /incl
      ctx.addInitialUndefinedSymbol(inputArg->getValue());
      break;

    case OPT_out:
      // handle /out
      ctx.setOutputPath(inputArg->getValue());
      break;

    case OPT_INPUT:
      inputGraph.addInputElement(std::unique_ptr<InputElement>(
          new PECOFFFileNode(ctx, inputArg->getValue())));
      break;

    default:
      break;
    }
  }

  // Use the default entry name if /entry option is not given.
  if (ctx.entrySymbolName().empty())
    ctx.setEntrySymbolName(getDefaultEntrySymbolName(ctx));

  // Specifying both /opt:ref and /opt:noref is an error.
  if (parsedArgs->getLastArg(OPT_ref) && parsedArgs->getLastArg(OPT_no_ref)) {
    diagnostics << "/opt:ref must not be specified with /opt:noref\n";
    return true;
  }

  // If dead-stripping is enabled, we need to add the entry symbol and
  // symbols given by /include to the dead strip root set, so that it
  // won't be removed from the output.
  if (ctx.deadStrip()) {
    ctx.addDeadStripRoot(ctx.entrySymbolName());
    for (const StringRef symbolName : ctx.initialUndefinedSymbols())
      ctx.addDeadStripRoot(symbolName);
  }

  // Arguments after "--" are interpreted as filenames even if they
  // start with a hypen or a slash. This is not compatible with link.exe
  // but useful for us to test lld on Unix.
  if (llvm::opt::Arg *dashdash = parsedArgs->getLastArg(OPT_DASH_DASH)) {
    for (const StringRef value : dashdash->getValues())
      inputGraph.addInputElement(
          std::unique_ptr<InputElement>(new PECOFFFileNode(ctx, value)));
  }

  // Add ".lib" extension if the path does not already have the extension to
  // mimic link.exe behavior.
  for (auto defaultLibPath : defaultLibs)
    inputGraph.addInputElement(std::unique_ptr<InputElement>(
        new PECOFFLibraryNode(ctx, defaultLibPath)));

  if (!inputGraph.numFiles()) {
    diagnostics << "No input files\n";
    return true;
  }

  // A list of undefined symbols will be added to the input
  // file list to force the core linker to try to resolve
  // the undefined symbols.
  inputGraph.addInternalFile(ctx.createInternalFiles());

  // If /out option was not specified, the default output file name is
  // constructed by replacing an extension of the first input file
  // with ".exe".
  if (ctx.outputPath().empty()) {
    SmallString<128> firstInputFilePath =
        *llvm::dyn_cast<FileNode>(&inputGraph[0])->path(ctx);
    llvm::sys::path::replace_extension(firstInputFilePath, ".exe");
    ctx.setOutputPath(ctx.allocateString(firstInputFilePath.str()));
  }

  // Validate the combination of options used.
  return ctx.validate(diagnostics);
}

} // namespace lld