//===--- ModuleDependencyCollector.cpp - Collect module dependencies ------===//

//

// 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

//

//===----------------------------------------------------------------------===//

//

// Collect the dependencies of a set of modules.

//

//===----------------------------------------------------------------------===//

#include "clang/Basic/CharInfo.h"

#include "clang/Frontend/Utils.h"

#include "clang/Lex/Preprocessor.h"

#include "clang/Serialization/ASTReader.h"

#include "llvm/ADT/iterator_range.h"

#include "llvm/Config/llvm-config.h"

#include "llvm/Support/FileSystem.h"

#include "llvm/Support/Path.h"

#include "llvm/Support/raw_ostream.h"

using namespace clang;

namespace {

/// Private implementations for ModuleDependencyCollector

class ModuleDependencyListener : public ASTReaderListener {

  ModuleDependencyCollector &Collector;

  FileManager &FileMgr;

public:

  ModuleDependencyListener(ModuleDependencyCollector &Collector,

                           FileManager &FileMgr)

      : Collector(Collector), FileMgr(FileMgr) {}

  bool needsInputFileVisitation() override { return true; }

  bool needsSystemInputFileVisitation() override { return true; }

  bool visitInputFile(StringRef Filename, bool IsSystem, bool IsOverridden,

                      bool IsExplicitModule) override {

    // Run this through the FileManager in order to respect 'use-external-name'

    // in case we have a VFS overlay.

    if (auto FE = FileMgr.getOptionalFileRef(Filename))

      Filename = FE->getName();

    Collector.addFile(Filename);

    return true;

  }

};

struct ModuleDependencyPPCallbacks : public PPCallbacks {

  ModuleDependencyCollector &Collector;

  SourceManager &SM;

  ModuleDependencyPPCallbacks(ModuleDependencyCollector &Collector,

                              SourceManager &SM)

      : Collector(Collector), SM(SM) {}

  void InclusionDirective(SourceLocation HashLoc, const Token &IncludeTok,

                          StringRef FileName, bool IsAngled,

                          CharSourceRange FilenameRange,

                          OptionalFileEntryRef File, StringRef SearchPath,

                          StringRef RelativePath, const Module *Imported,

                          SrcMgr::CharacteristicKind FileType) override {

    if (!File)

      return;

    Collector.addFile(File->getName());

  }

};

struct ModuleDependencyMMCallbacks : public ModuleMapCallbacks {

  ModuleDependencyCollector &Collector;

  ModuleDependencyMMCallbacks(ModuleDependencyCollector &Collector)

      : Collector(Collector) {}

  void moduleMapAddHeader(StringRef HeaderPath) override {

    if (llvm::sys::path::is_absolute(HeaderPath))

      Collector.addFile(HeaderPath);

  }

  void moduleMapAddUmbrellaHeader(FileEntryRef Header) override {

    moduleMapAddHeader(Header.getNameAsRequested());

  }

};

} // namespace

void ModuleDependencyCollector::attachToASTReader(ASTReader &R) {

  R.addListener(

      std::make_unique<ModuleDependencyListener>(*this, R.getFileManager()));

}

void ModuleDependencyCollector::attachToPreprocessor(Preprocessor &PP) {

  PP.addPPCallbacks(std::make_unique<ModuleDependencyPPCallbacks>(

      *this, PP.getSourceManager()));

  PP.getHeaderSearchInfo().getModuleMap().addModuleMapCallbacks(

      std::make_unique<ModuleDependencyMMCallbacks>(*this));

}

static bool isCaseSensitivePath(StringRef Path) {

  SmallString<256> TmpDest = Path, UpperDest, RealDest;

  // Remove component traversals, links, etc.

  if (llvm::sys::fs::real_path(Path, TmpDest))

    return true; // Current default value in vfs.yaml

  Path = TmpDest;

  // Change path to all upper case and ask for its real path, if the latter

  // exists and is equal to Path, it's not case sensitive. Default to case

  // sensitive in the absence of realpath, since this is what the VFSWriter

  // already expects when sensitivity isn't setup.

  for (auto &C : Path)

    UpperDest.push_back(toUppercase(C));

  if (!llvm::sys::fs::real_path(UpperDest, RealDest) && Path.equals(RealDest))

    return false;

  return true;

}

void ModuleDependencyCollector::writeFileMap() {

  if (Seen.empty())

    return;

  StringRef VFSDir = getDest();

  // Default to use relative overlay directories in the VFS yaml file. This

  // allows crash reproducer scripts to work across machines.

  VFSWriter.setOverlayDir(VFSDir);

  // Explicitly set case sensitivity for the YAML writer. For that, find out

  // the sensitivity at the path where the headers all collected to.

  VFSWriter.setCaseSensitivity(isCaseSensitivePath(VFSDir));

  // Do not rely on real path names when executing the crash reproducer scripts

  // since we only want to actually use the files we have on the VFS cache.

  VFSWriter.setUseExternalNames(false);

  std::error_code EC;

  SmallString<256> YAMLPath = VFSDir;

  llvm::sys::path::append(YAMLPath, "vfs.yaml");

  llvm::raw_fd_ostream OS(YAMLPath, EC, llvm::sys::fs::OF_TextWithCRLF);

  if (EC) {

    HasErrors = true;

    return;

  }

  VFSWriter.write(OS);

}

std::error_code ModuleDependencyCollector::copyToRoot(StringRef Src,

                                                      StringRef Dst) {

  using namespace llvm::sys;

  llvm::FileCollector::PathCanonicalizer::PathStorage Paths =

      Canonicalizer.canonicalize(Src);

  SmallString<256> CacheDst = getDest();

  if (Dst.empty()) {

    // The common case is to map the virtual path to the same path inside the

    // cache.

    path::append(CacheDst, path::relative_path(Paths.CopyFrom));

  } else {

    // When collecting entries from input vfsoverlays, copy the external

    // contents into the cache but still map from the source.

    if (!fs::exists(Dst))

      return std::error_code();

    path::append(CacheDst, Dst);

    Paths.CopyFrom = Dst;

  }

  // Copy the file into place.

  if (std::error_code EC = fs::create_directories(path::parent_path(CacheDst),

                                                  /*IgnoreExisting=*/true))

    return EC;

  if (std::error_code EC = fs::copy_file(Paths.CopyFrom, CacheDst))

    return EC;

  // Always map a canonical src path to its real path into the YAML, by doing

  // this we map different virtual src paths to the same entry in the VFS

  // overlay, which is a way to emulate symlink inside the VFS; this is also

  // needed for correctness, not doing that can lead to module redefinition

  // errors.

  addFileMapping(Paths.VirtualPath, CacheDst);

  return std::error_code();

}

void ModuleDependencyCollector::addFile(StringRef Filename, StringRef FileDst) {

  if (insertSeen(Filename))

    if (copyToRoot(Filename, FileDst))

      HasErrors = true;

}