From 6bc635ef56b9589a70e87737e788d9895e3cd0e4 Mon Sep 17 00:00:00 2001
From: Nico Weber <nicolasweber@gmx.de>
Date: Fri, 27 Apr 2018 20:29:57 +0000
Subject: [PATCH] Revert r329698 (and r329702).

Speculative. ClangMoveTests started failing on
http://lab.llvm.org:8011/builders/clang-x64-ninja-win7/builds/9958
after this change. I can't reproduce on my machine, let's see
if it was due to this change.

llvm-svn: 331077
---
 clang/lib/Basic/FileManager.cpp                  | 18 ++++++++++++++++--
 clang/lib/Frontend/ModuleDependencyCollector.cpp | 24 +++++++++++++++++++++---
 2 files changed, 37 insertions(+), 5 deletions(-)

diff --git a/clang/lib/Basic/FileManager.cpp b/clang/lib/Basic/FileManager.cpp
index 6fc00d9..719b2f6 100644
--- a/clang/lib/Basic/FileManager.cpp
+++ b/clang/lib/Basic/FileManager.cpp
@@ -534,9 +534,23 @@ StringRef FileManager::getCanonicalName(const DirectoryEntry *Dir) {
 
   StringRef CanonicalName(Dir->getName());
 
-  SmallString<256> CanonicalNameBuf;
-  if (!llvm::sys::fs::real_path(Dir->getName(), CanonicalNameBuf))
+#ifdef LLVM_ON_UNIX
+  char CanonicalNameBuf[PATH_MAX];
+  if (realpath(Dir->getName().str().c_str(), CanonicalNameBuf))
     CanonicalName = StringRef(CanonicalNameBuf).copy(CanonicalNameStorage);
+#else
+  SmallString<256> CanonicalNameBuf(CanonicalName);
+  llvm::sys::fs::make_absolute(CanonicalNameBuf);
+  llvm::sys::path::native(CanonicalNameBuf);
+  // We've run into needing to remove '..' here in the wild though, so
+  // remove it.
+  // On Windows, symlinks are significantly less prevalent, so removing
+  // '..' is pretty safe.
+  // Ideally we'd have an equivalent of `realpath` and could implement
+  // sys::fs::canonical across all the platforms.
+  llvm::sys::path::remove_dots(CanonicalNameBuf, /* remove_dot_dot */ true);
+  CanonicalName = StringRef(CanonicalNameBuf).copy(CanonicalNameStorage);
+#endif
 
   CanonicalDirNames.insert(std::make_pair(Dir, CanonicalName));
   return CanonicalName;
diff --git a/clang/lib/Frontend/ModuleDependencyCollector.cpp b/clang/lib/Frontend/ModuleDependencyCollector.cpp
index 5fa0e13..3546508 100644
--- a/clang/lib/Frontend/ModuleDependencyCollector.cpp
+++ b/clang/lib/Frontend/ModuleDependencyCollector.cpp
@@ -97,6 +97,24 @@ struct ModuleDependencyMMCallbacks : public ModuleMapCallbacks {
 
 }
 
+// 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));
 }
@@ -111,7 +129,7 @@ void ModuleDependencyCollector::attachToPreprocessor(Preprocessor &PP) {
 static bool isCaseSensitivePath(StringRef Path) {
   SmallString<256> TmpDest = Path, UpperDest, RealDest;
   // Remove component traversals, links, etc.
-  if (llvm::sys::fs::real_path(Path, TmpDest))
+  if (!real_path(Path, TmpDest))
     return true; // Current default value in vfs.yaml
   Path = TmpDest;
 
@@ -121,7 +139,7 @@ static bool isCaseSensitivePath(StringRef Path) {
   // 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))
+  if (real_path(UpperDest, RealDest) && Path.equals(RealDest))
     return false;
   return true;
 }
@@ -171,7 +189,7 @@ bool ModuleDependencyCollector::getRealPath(StringRef SrcPath,
   // Computing the real path is expensive, cache the search through the
   // parent path directory.
   if (DirWithSymLink == SymLinkMap.end()) {
-    if (llvm::sys::fs::real_path(Dir, RealPath))
+    if (!real_path(Dir, RealPath))
       return false;
     SymLinkMap[Dir] = RealPath.str();
   } else {
-- 
2.7.4