1 files changed, 268 insertions, 0 deletions
diff --git a/llvm/lib/Support/FileCollector.cpp b/llvm/lib/Support/FileCollector.cpp
new file mode 100644
index 000000000000..47fca6413722
--- /dev/null
+++ b/llvm/lib/Support/FileCollector.cpp
@@ -0,0 +1,268 @@
+//===-- FileCollector.cpp ---------------------------------------*- 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 "llvm/Support/FileCollector.h"
+#include "llvm/ADT/SmallString.h"
+#include "llvm/Support/FileSystem.h"
+#include "llvm/Support/Path.h"
+#include "llvm/Support/Process.h"
+
+using namespace llvm;
+
+static bool isCaseSensitivePath(StringRef Path) {
+  SmallString<256> TmpDest = Path, UpperDest, RealDest;
+
+  // Remove component traversals, links, etc.
+  if (!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 real_path, since this is the YAMLVFSWriter
+  // default.
+  UpperDest = Path.upper();
+  if (sys::fs::real_path(UpperDest, RealDest) && Path.equals(RealDest))
+    return false;
+  return true;
+}
+
+FileCollector::FileCollector(std::string Root, std::string OverlayRoot)
+    : Root(std::move(Root)), OverlayRoot(std::move(OverlayRoot)) {
+  sys::fs::create_directories(this->Root, true);
+}
+
+bool FileCollector::getRealPath(StringRef SrcPath,
+                                SmallVectorImpl<char> &Result) {
+  SmallString<256> RealPath;
+  StringRef FileName = sys::path::filename(SrcPath);
+  std::string Directory = sys::path::parent_path(SrcPath).str();
+  auto DirWithSymlink = SymlinkMap.find(Directory);
+
+  // Use real_path to fix any symbolic link component present in a path.
+  // Computing the real path is expensive, cache the search through the parent
+  // path Directory.
+  if (DirWithSymlink == SymlinkMap.end()) {
+    auto EC = sys::fs::real_path(Directory, RealPath);
+    if (EC)
+      return false;
+    SymlinkMap[Directory] = RealPath.str();
+  } else {
+    RealPath = DirWithSymlink->second;
+  }
+
+  sys::path::append(RealPath, FileName);
+  Result.swap(RealPath);
+  return true;
+}
+
+void FileCollector::addFile(const Twine &file) {
+  std::lock_guard<std::mutex> lock(Mutex);
+  std::string FileStr = file.str();
+  if (markAsSeen(FileStr))
+    addFileImpl(FileStr);
+}
+
+void FileCollector::addFileImpl(StringRef SrcPath) {
+  // We need an absolute src path to append to the root.
+  SmallString<256> AbsoluteSrc = SrcPath;
+  sys::fs::make_absolute(AbsoluteSrc);
+
+  // Canonicalize src to a native path to avoid mixed separator styles.
+  sys::path::native(AbsoluteSrc);
+
+  // Remove redundant leading "./" pieces and consecutive separators.
+  AbsoluteSrc = sys::path::remove_leading_dotslash(AbsoluteSrc);
+
+  // Canonicalize the source path by removing "..", "." components.
+  SmallString<256> VirtualPath = AbsoluteSrc;
+  sys::path::remove_dots(VirtualPath, /*remove_dot_dot=*/true);
+
+  // If a ".." component is present after a symlink component, remove_dots may
+  // lead to the wrong real destination path. Let the source be canonicalized
+  // like that but make sure we always use the real path for the destination.
+  SmallString<256> CopyFrom;
+  if (!getRealPath(AbsoluteSrc, CopyFrom))
+    CopyFrom = VirtualPath;
+
+  SmallString<256> DstPath = StringRef(Root);
+  sys::path::append(DstPath, sys::path::relative_path(CopyFrom));
+
+  // 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.
+  addFileToMapping(VirtualPath, DstPath);
+}
+
+/// Set the access and modification time for the given file from the given
+/// status object.
+static std::error_code
+copyAccessAndModificationTime(StringRef Filename,
+                              const sys::fs::file_status &Stat) {
+  int FD;
+
+  if (auto EC =
+          sys::fs::openFileForWrite(Filename, FD, sys::fs::CD_OpenExisting))
+    return EC;
+
+  if (auto EC = sys::fs::setLastAccessAndModificationTime(
+          FD, Stat.getLastAccessedTime(), Stat.getLastModificationTime()))
+    return EC;
+
+  if (auto EC = sys::Process::SafelyCloseFileDescriptor(FD))
+    return EC;
+
+  return {};
+}
+
+std::error_code FileCollector::copyFiles(bool StopOnError) {
+  for (auto &entry : VFSWriter.getMappings()) {
+    // Create directory tree.
+    if (std::error_code EC =
+            sys::fs::create_directories(sys::path::parent_path(entry.RPath),
+                                        /*IgnoreExisting=*/true)) {
+      if (StopOnError)
+        return EC;
+    }
+
+    // Get the status of the original file/directory.
+    sys::fs::file_status Stat;
+    if (std::error_code EC = sys::fs::status(entry.VPath, Stat)) {
+      if (StopOnError)
+        return EC;
+      continue;
+    }
+
+    if (Stat.type() == sys::fs::file_type::directory_file) {
+      // Construct a directory when it's just a directory entry.
+      if (std::error_code EC =
+              sys::fs::create_directories(entry.RPath,
+                                          /*IgnoreExisting=*/true)) {
+        if (StopOnError)
+          return EC;
+      }
+      continue;
+    }
+
+    // Copy file over.
+    if (std::error_code EC = sys::fs::copy_file(entry.VPath, entry.RPath)) {
+      if (StopOnError)
+        return EC;
+    }
+
+    // Copy over permissions.
+    if (auto perms = sys::fs::getPermissions(entry.VPath)) {
+      if (std::error_code EC = sys::fs::setPermissions(entry.RPath, *perms)) {
+        if (StopOnError)
+          return EC;
+      }
+    }
+
+    // Copy over modification time.
+    copyAccessAndModificationTime(entry.RPath, Stat);
+  }
+  return {};
+}
+
+std::error_code FileCollector::writeMapping(StringRef mapping_file) {
+  std::lock_guard<std::mutex> lock(Mutex);
+
+  VFSWriter.setOverlayDir(OverlayRoot);
+  VFSWriter.setCaseSensitivity(isCaseSensitivePath(OverlayRoot));
+  VFSWriter.setUseExternalNames(false);
+
+  std::error_code EC;
+  raw_fd_ostream os(mapping_file, EC, sys::fs::OF_Text);
+  if (EC)
+    return EC;
+
+  VFSWriter.write(os);
+
+  return {};
+}
+
+namespace {
+
+class FileCollectorFileSystem : public vfs::FileSystem {
+public:
+  explicit FileCollectorFileSystem(IntrusiveRefCntPtr<vfs::FileSystem> FS,
+                                   std::shared_ptr<FileCollector> Collector)
+      : FS(std::move(FS)), Collector(std::move(Collector)) {}
+
+  llvm::ErrorOr<llvm::vfs::Status> status(const Twine &Path) override {
+    auto Result = FS->status(Path);
+    if (Result && Result->exists())
+      Collector->addFile(Path);
+    return Result;
+  }
+
+  llvm::ErrorOr<std::unique_ptr<llvm::vfs::File>>
+  openFileForRead(const Twine &Path) override {
+    auto Result = FS->openFileForRead(Path);
+    if (Result && *Result)
+      Collector->addFile(Path);
+    return Result;
+  }
+
+  llvm::vfs::directory_iterator dir_begin(const llvm::Twine &Dir,
+                                          std::error_code &EC) override {
+    auto It = FS->dir_begin(Dir, EC);
+    if (EC)
+      return It;
+    // Collect everything that's listed in case the user needs it.
+    Collector->addFile(Dir);
+    for (; !EC && It != llvm::vfs::directory_iterator(); It.increment(EC)) {
+      if (It->type() == sys::fs::file_type::regular_file ||
+          It->type() == sys::fs::file_type::directory_file ||
+          It->type() == sys::fs::file_type::symlink_file) {
+        Collector->addFile(It->path());
+      }
+    }
+    if (EC)
+      return It;
+    // Return a new iterator.
+    return FS->dir_begin(Dir, EC);
+  }
+
+  std::error_code getRealPath(const Twine &Path,
+                              SmallVectorImpl<char> &Output) const override {
+    auto EC = FS->getRealPath(Path, Output);
+    if (!EC) {
+      Collector->addFile(Path);
+      if (Output.size() > 0)
+        Collector->addFile(Output);
+    }
+    return EC;
+  }
+
+  std::error_code isLocal(const Twine &Path, bool &Result) override {
+    return FS->isLocal(Path, Result);
+  }
+
+  llvm::ErrorOr<std::string> getCurrentWorkingDirectory() const override {
+    return FS->getCurrentWorkingDirectory();
+  }
+
+  std::error_code setCurrentWorkingDirectory(const llvm::Twine &Path) override {
+    return FS->setCurrentWorkingDirectory(Path);
+  }
+
+private:
+  IntrusiveRefCntPtr<vfs::FileSystem> FS;
+  std::shared_ptr<FileCollector> Collector;
+};
+
+} // end anonymous namespace
+
+IntrusiveRefCntPtr<vfs::FileSystem>
+FileCollector::createCollectorVFS(IntrusiveRefCntPtr<vfs::FileSystem> BaseFS,
+                                  std::shared_ptr<FileCollector> Collector) {
+  return new FileCollectorFileSystem(std::move(BaseFS), std::move(Collector));
+}