1 files changed, 39 insertions, 15 deletions

diff --git a/clang/lib/Basic/VirtualFileSystem.cpp b/clang/lib/Basic/VirtualFileSystem.cpp
index 6977f40..68ad428 100644
--- a/clang/lib/Basic/VirtualFileSystem.cpp
+++ b/clang/lib/Basic/VirtualFileSystem.cpp
@@ -111,6 +111,20 @@ bool FileSystem::exists(const Twine &Path) {
   return Status && Status->exists();
 }
 
+#ifndef NDEBUG
+static bool isTraversalComponent(StringRef Component) {
+  return Component.equals("..") || Component.equals(".");
+}
+
+static bool pathHasTraversal(StringRef Path) {
+  using namespace llvm::sys;
+  for (StringRef Comp : llvm::make_range(path::begin(Path), path::end(Path)))
+    if (isTraversalComponent(Comp))
+      return true;
+  return false;
+}
+#endif
+
 //===-----------------------------------------------------------------------===/
 // RealFileSystem implementation
 //===-----------------------------------------------------------------------===/
@@ -807,6 +821,9 @@ public:
 ///
 /// and inherit their attributes from the external contents.
 ///
+/// Virtual file paths and external files are expected to be canonicalized
+/// without "..", "." and "./" in their paths.
+///
 /// In both cases, the 'name' field may contain multiple path components (e.g.
 /// /path/to/file). However, any directory that contains more than one child
 /// must be uniquely represented by a directory entry.
@@ -1004,7 +1021,13 @@ class RedirectingFileSystemParser {
       if (Key == "name") {
         if (!parseScalarString(I->getValue(), Value, Buffer))
           return nullptr;
-        Name = Value;
+
+        SmallString<256> Path(Value);
+        // Guarantee that old YAML files containing paths with ".." and "." are
+        // properly canonicalized before read into the VFS.
+        Path = sys::path::remove_leading_dotslash(Path);
+        sys::path::remove_dots(Path, /*remove_dot_dot=*/true);
+        Name = Path.str();
       } else if (Key == "type") {
         if (!parseScalarString(I->getValue(), Value, Buffer))
           return nullptr;
@@ -1048,7 +1071,12 @@ class RedirectingFileSystemParser {
         HasContents = true;
         if (!parseScalarString(I->getValue(), Value, Buffer))
           return nullptr;
-        ExternalContentsPath = Value;
+        SmallString<256> Path(Value);
+        // Guarantee that old YAML files containing paths with ".." and "." are
+        // properly canonicalized before read into the VFS.
+        Path = sys::path::remove_leading_dotslash(Path);
+        sys::path::remove_dots(Path, /*remove_dot_dot=*/true);
+        ExternalContentsPath = Path.str();
       } else if (Key == "use-external-name") {
         bool Val;
         if (!parseScalarBool(I->getValue(), Val))
@@ -1238,6 +1266,12 @@ ErrorOr<Entry *> RedirectingFileSystem::lookupPath(const Twine &Path_) {
   if (std::error_code EC = makeAbsolute(Path))
     return EC;
 
+  // Canonicalize path by removing ".", "..", "./", etc components. This is
+  // a VFS request, do bot bother about symlinks in the path components
+  // but canonicalize in order to perform the correct entry search.
+  Path = sys::path::remove_leading_dotslash(Path);
+  sys::path::remove_dots(Path, /*remove_dot_dot=*/true);
+
   if (Path.empty())
     return make_error_code(llvm::errc::invalid_argument);
 
@@ -1254,10 +1288,10 @@ ErrorOr<Entry *> RedirectingFileSystem::lookupPath(const Twine &Path_) {
 ErrorOr<Entry *>
 RedirectingFileSystem::lookupPath(sys::path::const_iterator Start,
                                   sys::path::const_iterator End, Entry *From) {
-  if (Start->equals("."))
-    ++Start;
+  assert(!isTraversalComponent(*Start) &&
+         !isTraversalComponent(From->getName()) &&
+         "Paths should not contain traversal components");
 
-  // FIXME: handle ..
   if (CaseSensitive ? !Start->equals(From->getName())
                     : !Start->equals_lower(From->getName()))
     // failure to match
@@ -1376,16 +1410,6 @@ UniqueID vfs::getNextVirtualUniqueID() {
   return UniqueID(std::numeric_limits<uint64_t>::max(), ID);
 }
 
-#ifndef NDEBUG
-static bool pathHasTraversal(StringRef Path) {
-  using namespace llvm::sys;
-  for (StringRef Comp : llvm::make_range(path::begin(Path), path::end(Path)))
-    if (Comp == "." || Comp == "..")
-      return true;
-  return false;
-}
-#endif
-
 void YAMLVFSWriter::addFileMapping(StringRef VirtualPath, StringRef RealPath) {
   assert(sys::path::is_absolute(VirtualPath) && "virtual path not absolute");
   assert(sys::path::is_absolute(RealPath) && "real path not absolute");