ELF/DriverUtils.cpp

//===- DriverUtils.cpp ----------------------------------------------------===//
//
//                             The LLVM Linker
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file contains utility functions for the driver. Because there
// are so many small functions, we created this separate file to make
// Driver.cpp less cluttered.
//
//===----------------------------------------------------------------------===//

#include "Driver.h"
#include "Error.h"
#include "lld/Config/Version.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/Triple.h"
#include "llvm/Option/Option.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/Path.h"
#include "llvm/Support/StringSaver.h"

using namespace llvm;
using namespace llvm::sys;

using namespace lld;
using namespace lld::elf;

// Create OptTable

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

// Create table mapping all options defined in Options.td
static const opt::OptTable::Info OptInfo[] = {
#define OPTION(X1, X2, ID, KIND, GROUP, ALIAS, X6, X7, X8, X9, X10)            \
  {                                                                            \
    X1, X2, X9, X10, OPT_##ID, opt::Option::KIND##Class, X8, X7, OPT_##GROUP,  \
        OPT_##ALIAS, X6                                                        \
  },
#include "Options.inc"
#undef OPTION
};

ELFOptTable::ELFOptTable() : OptTable(OptInfo) {}

static cl::TokenizerCallback getQuotingStyle(opt::InputArgList &Args) {
  if (auto *Arg = Args.getLastArg(OPT_rsp_quoting)) {
    StringRef S = Arg->getValue();
    if (S != "windows" && S != "posix")
      error("invalid response file quoting: " + S);
    if (S == "windows")
      return cl::TokenizeWindowsCommandLine;
    return cl::TokenizeGNUCommandLine;
  }
  if (Triple(sys::getProcessTriple()).getOS() == Triple::Win32)
    return cl::TokenizeWindowsCommandLine;
  return cl::TokenizeGNUCommandLine;
}

// Parses a given list of options.
opt::InputArgList ELFOptTable::parse(ArrayRef<const char *> Argv) {
  // Make InputArgList from string vectors.
  unsigned MissingIndex;
  unsigned MissingCount;
  SmallVector<const char *, 256> Vec(Argv.data(), Argv.data() + Argv.size());

  // We need to get the quoting style for response files before parsing all
  // options so we parse here before and ignore all the options but
  // --rsp-quoting.
  opt::InputArgList Args = this->ParseArgs(Vec, MissingIndex, MissingCount);

  // Expand response files. '@<filename>' is replaced by the file's contents.
  StringSaver Saver(Alloc);
  cl::ExpandResponseFiles(Saver, getQuotingStyle(Args), Vec);

  // Parse options and then do error checking.
  Args = this->ParseArgs(Vec, MissingIndex, MissingCount);
  if (MissingCount)
    error(Twine("missing arg value for \"") + Args.getArgString(MissingIndex) +
          "\", expected " + Twine(MissingCount) +
          (MissingCount == 1 ? " argument.\n" : " arguments"));

  for (auto *Arg : Args.filtered(OPT_UNKNOWN))
    error("unknown argument: " + Arg->getSpelling());
  return Args;
}

void elf::printHelp(const char *Argv0) {
  ELFOptTable Table;
  Table.PrintHelp(outs(), Argv0, "lld", false);
}

std::string elf::getVersionString() {
  std::string Version = getLLDVersion();
  std::string Repo = getLLDRepositoryVersion();
  if (Repo.empty())
    return "LLD " + Version + "\n";
  return "LLD " + Version + " " + Repo + "\n";
}

// Makes a given pathname an absolute path first, and then remove
// beginning /. For example, "../foo.o" is converted to "home/john/foo.o",
// assuming that the current directory is "/home/john/bar".
std::string elf::relativeToRoot(StringRef Path) {
  SmallString<128> Abs = Path;
  if (std::error_code EC = fs::make_absolute(Abs))
    fatal("make_absolute failed: " + EC.message());
  path::remove_dots(Abs, /*remove_dot_dot=*/true);

  // This is Windows specific. root_name() returns a drive letter
  // (e.g. "c:") or a UNC name (//net). We want to keep it as part
  // of the result.
  SmallString<128> Res;
  StringRef Root = path::root_name(Abs);
  if (Root.endswith(":"))
    Res = Root.drop_back();
  else if (Root.startswith("//"))
    Res = Root.substr(2);

  path::append(Res, path::relative_path(Abs));
  return Res.str();
}

CpioFile::CpioFile(std::unique_ptr<raw_fd_ostream> OS, StringRef S)
    : OS(std::move(OS)), Basename(S) {}

CpioFile *CpioFile::create(StringRef OutputPath) {
  std::string Path = (OutputPath + ".cpio").str();
  std::error_code EC;
  auto OS = llvm::make_unique<raw_fd_ostream>(Path, EC, fs::F_None);
  if (EC) {
    error(EC, "--reproduce: failed to open " + Path);
    return nullptr;
  }
  return new CpioFile(std::move(OS), path::filename(OutputPath));
}

static void writeMember(raw_fd_ostream &OS, StringRef Path, StringRef Data) {
  // The c_dev/c_ino pair should be unique according to the spec,
  // but no one seems to care.
  OS << "070707";                        // c_magic
  OS << "000000";                        // c_dev
  OS << "000000";                        // c_ino
  OS << "100664";                        // c_mode: C_ISREG | rw-rw-r--
  OS << "000000";                        // c_uid
  OS << "000000";                        // c_gid
  OS << "000001";                        // c_nlink
  OS << "000000";                        // c_rdev
  OS << "00000000000";                   // c_mtime
  OS << format("%06o", Path.size() + 1); // c_namesize
  OS << format("%011o", Data.size());    // c_filesize
  OS << Path << '\0';                    // c_name
  OS << Data;                            // c_filedata
}

void CpioFile::append(StringRef Path, StringRef Data) {
  if (!Seen.insert(Path).second)
    return;

  // Construct an in-archive filename so that /home/foo/bar is stored
  // as baz/home/foo/bar where baz is the basename of the output file.
  // (i.e. in that case we are creating baz.cpio.)
  SmallString<128> Fullpath;
  path::append(Fullpath, Basename, Path);

  // Use unix path separators so the cpio can be extracted on both unix and
  // windows.
  std::replace(Fullpath.begin(), Fullpath.end(), '\\', '/');

  writeMember(*OS, Fullpath, Data);

  // Print the trailer and seek back.
  // This way we have a valid archive if we crash.
  uint64_t Pos = OS->tell();
  writeMember(*OS, "TRAILER!!!", "");
  OS->seek(Pos);
}

// Quote a given string if it contains a space character.
static std::string quote(StringRef S) {
  if (S.find(' ') == StringRef::npos)
    return S;
  return ("\"" + S + "\"").str();
}

static std::string rewritePath(StringRef S) {
  if (fs::exists(S))
    return relativeToRoot(S);
  return S;
}

static std::string stringize(opt::Arg *Arg) {
  std::string K = Arg->getSpelling();
  if (Arg->getNumValues() == 0)
    return K;
  std::string V = quote(Arg->getValue());
  if (Arg->getOption().getRenderStyle() == opt::Option::RenderJoinedStyle)
    return K + V;
  return K + " " + V;
}

// Reconstructs command line arguments so that so that you can re-run
// the same command with the same inputs. This is for --reproduce.
std::string elf::createResponseFile(const opt::InputArgList &Args) {
  SmallString<0> Data;
  raw_svector_ostream OS(Data);

  // Copy the command line to the output while rewriting paths.
  for (auto *Arg : Args) {
    switch (Arg->getOption().getID()) {
    case OPT_reproduce:
      break;
    case OPT_INPUT:
      OS << quote(rewritePath(Arg->getValue())) << "\n";
      break;
    case OPT_L:
    case OPT_dynamic_list:
    case OPT_rpath:
    case OPT_alias_script_T:
    case OPT_script:
    case OPT_version_script:
      OS << Arg->getSpelling() << " "
         << quote(rewritePath(Arg->getValue())) << "\n";
      break;
    default:
      OS << stringize(Arg) << "\n";
    }
  }
  return Data.str();
}

std::string elf::findFromSearchPaths(StringRef Path) {
  for (StringRef Dir : Config->SearchPaths) {
    std::string FullPath = buildSysrootedPath(Dir, Path);
    if (fs::exists(FullPath))
      return FullPath;
  }
  return "";
}

// Searches a given library from input search paths, which are filled
// from -L command line switches. Returns a path to an existent library file.
std::string elf::searchLibrary(StringRef Path) {
  if (Path.startswith(":"))
    return findFromSearchPaths(Path.substr(1));
  for (StringRef Dir : Config->SearchPaths) {
    if (!Config->Static) {
      std::string S = buildSysrootedPath(Dir, ("lib" + Path + ".so").str());
      if (fs::exists(S))
        return S;
    }
    std::string S = buildSysrootedPath(Dir, ("lib" + Path + ".a").str());
    if (fs::exists(S))
      return S;
  }
  return "";
}

// Makes a path by concatenating Dir and File.
// If Dir starts with '=' the result will be preceded by Sysroot,
// which can be set with --sysroot command line switch.
std::string elf::buildSysrootedPath(StringRef Dir, StringRef File) {
  SmallString<128> Path;
  if (Dir.startswith("="))
    path::append(Path, Config->Sysroot, Dir.substr(1), File);
  else
    path::append(Path, Dir, File);
  return Path.str();
}