1 files changed, 158 insertions, 27 deletions

diff --git a/lib/Frontend/ModuleDependencyCollector.cpp b/lib/Frontend/ModuleDependencyCollector.cpp
index 9768a164acbc..ca11f9b863bb 100644
--- a/lib/Frontend/ModuleDependencyCollector.cpp
+++ b/lib/Frontend/ModuleDependencyCollector.cpp
@@ -11,9 +11,11 @@
 //
 //===----------------------------------------------------------------------===//
 
+#include "clang/Basic/CharInfo.h"
 #include "clang/Frontend/Utils.h"
+#include "clang/Lex/Preprocessor.h"
 #include "clang/Serialization/ASTReader.h"
-#include "llvm/ADT/StringSet.h"
+#include "llvm/ADT/StringMap.h"
 #include "llvm/ADT/iterator_range.h"
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/Path.h"
@@ -22,73 +24,202 @@
 using namespace clang;
 
 namespace {
-/// Private implementation for ModuleDependencyCollector
+/// Private implementations 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,
-                      bool IsExplicitModule) override;
+                      bool IsExplicitModule) override {
+    Collector.addFile(Filename);
+    return true;
+  }
+};
+
+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(FileManager *FileMgr,
+                                  const FileEntry *Header) override {
+    StringRef HeaderFilename = Header->getName();
+    moduleMapAddHeader(HeaderFilename);
+    // The FileManager can find and cache the symbolic link for a framework
+    // header before its real path, this means a module can have some of its
+    // headers to use other paths. Although this is usually not a problem, it's
+    // inconsistent, and not collecting the original path header leads to
+    // umbrella clashes while rebuilding modules in the crash reproducer. For
+    // example:
+    //    ApplicationServices.framework/Frameworks/ImageIO.framework/ImageIO.h
+    // instead of:
+    //    ImageIO.framework/ImageIO.h
+    //
+    // FIXME: this shouldn't be necessary once we have FileName instances
+    // around instead of FileEntry ones. For now, make sure we collect all
+    // that we need for the reproducer to work correctly.
+    StringRef UmbreallDirFromHeader =
+        llvm::sys::path::parent_path(HeaderFilename);
+    StringRef UmbrellaDir = Header->getDir()->getName();
+    if (!UmbrellaDir.equals(UmbreallDirFromHeader)) {
+      SmallString<128> AltHeaderFilename;
+      llvm::sys::path::append(AltHeaderFilename, UmbrellaDir,
+                              llvm::sys::path::filename(HeaderFilename));
+      if (FileMgr->getFile(AltHeaderFilename))
+        moduleMapAddHeader(AltHeaderFilename);
+    }
+  }
 };
+
+}
+
+// TODO: move this to Support/Path.h and check for HAVE_REALPATH?
+static bool real_path(StringRef SrcPath, SmallVectorImpl<char> &RealPath) {
+#ifdef LLVM_ON_UNIX
+  char CanonicalPath[PATH_MAX];
+
+  // TODO: emit a warning in case this fails...?
+  if (!realpath(SrcPath.str().c_str(), CanonicalPath))
+    return false;
+
+  SmallString<256> RPath(CanonicalPath);
+  RealPath.swap(RPath);
+  return true;
+#else
+  // FIXME: Add support for systems without realpath.
+  return false;
+#endif
 }
 
 void ModuleDependencyCollector::attachToASTReader(ASTReader &R) {
   R.addListener(llvm::make_unique<ModuleDependencyListener>(*this));
 }
 
+void ModuleDependencyCollector::attachToPreprocessor(Preprocessor &PP) {
+  PP.getHeaderSearchInfo().getModuleMap().addModuleMapCallbacks(
+      llvm::make_unique<ModuleDependencyMMCallbacks>(*this));
+}
+
+static bool isCaseSensitivePath(StringRef Path) {
+  SmallString<256> TmpDest = Path, UpperDest, RealDest;
+  // Remove component traversals, links, etc.
+  if (!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 absense 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 (real_path(UpperDest, RealDest) && Path.equals(RealDest))
+    return false;
+  return true;
+}
+
 void ModuleDependencyCollector::writeFileMap() {
   if (Seen.empty())
     return;
 
-  SmallString<256> Dest = getDest();
-  llvm::sys::path::append(Dest, "vfs.yaml");
+  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;
-  llvm::raw_fd_ostream OS(Dest, EC, llvm::sys::fs::F_Text);
+  SmallString<256> YAMLPath = VFSDir;
+  llvm::sys::path::append(YAMLPath, "vfs.yaml");
+  llvm::raw_fd_ostream OS(YAMLPath, EC, llvm::sys::fs::F_Text);
   if (EC) {
-    setHasErrors();
+    HasErrors = true;
     return;
   }
   VFSWriter.write(OS);
 }
 
-std::error_code ModuleDependencyListener::copyToRoot(StringRef Src) {
+bool ModuleDependencyCollector::getRealPath(StringRef SrcPath,
+                                            SmallVectorImpl<char> &Result) {
+  using namespace llvm::sys;
+  SmallString<256> RealPath;
+  StringRef FileName = path::filename(SrcPath);
+  std::string Dir = path::parent_path(SrcPath).str();
+  auto DirWithSymLink = SymLinkMap.find(Dir);
+
+  // 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()) {
+    if (!real_path(Dir, RealPath))
+      return false;
+    SymLinkMap[Dir] = RealPath.str();
+  } else {
+    RealPath = DirWithSymLink->second;
+  }
+
+  path::append(RealPath, FileName);
+  Result.swap(RealPath);
+  return true;
+}
+
+std::error_code ModuleDependencyCollector::copyToRoot(StringRef Src) {
   using namespace llvm::sys;
 
-  // We need an absolute path to append to the root.
+  // We need an absolute src path to append to the root.
   SmallString<256> AbsoluteSrc = Src;
   fs::make_absolute(AbsoluteSrc);
-  // Canonicalize to a native path to avoid mixed separator styles.
+  // Canonicalize src to a native path to avoid mixed separator styles.
   path::native(AbsoluteSrc);
-  // TODO: We probably need to handle .. as well as . in order to have valid
-  // input to the YAMLVFSWriter.
-  path::remove_dots(AbsoluteSrc);
+  // Remove redundant leading "./" pieces and consecutive separators.
+  AbsoluteSrc = path::remove_leading_dotslash(AbsoluteSrc);
 
-  // Build the destination path.
-  SmallString<256> Dest = Collector.getDest();
-  path::append(Dest, path::relative_path(AbsoluteSrc));
+  // Canonicalize the source path by removing "..", "." components.
+  SmallString<256> CanonicalPath = AbsoluteSrc;
+  path::remove_dots(CanonicalPath, /*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> RealPath;
+  if (!getRealPath(AbsoluteSrc, RealPath))
+    RealPath = CanonicalPath;
+  SmallString<256> Dest = getDest();
+  path::append(Dest, path::relative_path(RealPath));
 
   // 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, Dest))
+  if (std::error_code EC = fs::copy_file(RealPath, Dest))
     return EC;
-  // Use the absolute path under the root for the file mapping.
-  Collector.addFileMapping(AbsoluteSrc, Dest);
+
+  // 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 redifinition
+  // errors.
+  addFileMapping(CanonicalPath, Dest);
   return std::error_code();
 }
 
-bool ModuleDependencyListener::visitInputFile(StringRef Filename, bool IsSystem,
-                                              bool IsOverridden,
-                                              bool IsExplicitModule) {
-  if (Collector.insertSeen(Filename))
+void ModuleDependencyCollector::addFile(StringRef Filename) {
+  if (insertSeen(Filename))
     if (copyToRoot(Filename))
-      Collector.setHasErrors();
-  return true;
+      HasErrors = true;
 }