1 files changed, 109 insertions, 0 deletions
diff --git a/clang/lib/Frontend/ModuleDependencyCollector.cpp b/clang/lib/Frontend/ModuleDependencyCollector.cpp
new file mode 100644
index 00000000000..8e4402b8eda
--- /dev/null
+++ b/clang/lib/Frontend/ModuleDependencyCollector.cpp
@@ -0,0 +1,109 @@
+//===--- ModuleDependencyCollector.cpp - Collect module dependencies ------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// Collect the dependencies of a set of modules.
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/Frontend/Utils.h"
+#include "clang/Serialization/ASTReader.h"
+#include "llvm/ADT/iterator_range.h"
+#include "llvm/ADT/StringSet.h"
+#include "llvm/Support/Filesystem.h"
+#include "llvm/Support/Path.h"
+#include "llvm/Support/raw_ostream.h"
+
+using namespace clang;
+
+namespace {
+/// Private implementation for ModuleDependencyCollector
+class ModuleDependencyListener : public ASTReaderListener {
+  ModuleDependencyCollector &Collector;
+
+  std::error_code copyToRoot(StringRef Src);
+public:
+  ModuleDependencyListener(ModuleDependencyCollector &Collector)
+      : Collector(Collector) {}
+  bool needsInputFileVisitation() override { return true; }
+  bool needsSystemInputFileVisitation() override { return true; }
+  bool visitInputFile(StringRef Filename, bool IsSystem,
+                      bool IsOverridden) override;
+};
+}
+
+void ModuleDependencyCollector::attachToASTReader(ASTReader &R) {
+  R.addListener(new ModuleDependencyListener(*this));
+}
+
+void ModuleDependencyCollector::writeFileMap() {
+  if (Seen.empty())
+    return;
+
+  SmallString<256> Dest = getDest();
+  llvm::sys::path::append(Dest, "vfs.yaml");
+
+  std::string ErrorInfo;
+  llvm::raw_fd_ostream OS(Dest.c_str(), ErrorInfo, llvm::sys::fs::F_Text);
+  if (!ErrorInfo.empty()) {
+    setHasErrors();
+    return;
+  }
+  VFSWriter.write(OS);
+}
+
+/// Append the absolute path in Nested to the path given by Root. This will
+/// remove directory traversal from the resulting nested path.
+static void appendNestedPath(SmallVectorImpl<char> &Root, StringRef Nested) {
+  using namespace llvm::sys;
+  SmallVector<StringRef, 16> ComponentStack;
+
+  StringRef Rel = path::relative_path(Nested);
+  for (StringRef C : llvm::make_range(path::begin(Rel), path::end(Rel))) {
+    if (C == ".")
+      continue;
+    if (C == "..") {
+      assert(ComponentStack.size() && "Path traverses out of parent");
+      ComponentStack.pop_back();
+    } else
+      ComponentStack.push_back(C);
+  }
+  // The stack is now the path without any directory traversal.
+  for (StringRef C : ComponentStack)
+    path::append(Root, C);
+}
+
+std::error_code ModuleDependencyListener::copyToRoot(StringRef Src) {
+  using namespace llvm::sys;
+
+  // We need an absolute path to append to the root.
+  SmallString<256> AbsoluteSrc = Src;
+  fs::make_absolute(AbsoluteSrc);
+  // Build the destination path.
+  SmallString<256> Dest = Collector.getDest();
+  size_t RootLen = Dest.size();
+  appendNestedPath(Dest, AbsoluteSrc);
+
+  // Copy the file into place.
+  if (std::error_code EC = fs::create_directories(path::parent_path(Dest),
+                                                   /*IgnoreExisting=*/true))
+    return EC;
+  if (std::error_code EC = fs::copy_file(AbsoluteSrc.str(), Dest.str()))
+    return EC;
+  // Use the absolute path under the root for the file mapping.
+  Collector.addFileMapping(Dest.substr(RootLen), Dest.str());
+  return std::error_code();
+}
+
+bool ModuleDependencyListener::visitInputFile(StringRef Filename, bool IsSystem,
+                                              bool IsOverridden) {
+  if (Collector.insertSeen(Filename))
+    if (copyToRoot(Filename))
+      Collector.setHasErrors();
+  return true;
+}