From 404a72729be98fbc41051197e0c9bb1b48c28e94 Mon Sep 17 00:00:00 2001
From: Saleem Abdulrasool <compnerd@compnerd.org>
Date: Tue, 11 Mar 2014 22:05:42 +0000
Subject: [PATCH] support: add a utility function to normalise path separators

Add a utility function to convert the Windows path separator to Unix style path
separators.  This is used by a subsequent change in clang to enable the use of
Windows SDK headers on Linux.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@203611 91177308-0d34-0410-b5e6-96231b3b80d8
---
 include/llvm/Support/FileSystem.h |  8 +++++++
 lib/Support/Unix/Path.inc         | 13 +++++++++++
 lib/Support/Windows/Path.inc      |  5 +++++
 unittests/Support/Path.cpp        | 37 +++++++++++++++++++++++++++++++
 4 files changed, 63 insertions(+)

diff --git a/include/llvm/Support/FileSystem.h b/include/llvm/Support/FileSystem.h
index 906f37f7c18..c5c84157533 100644
--- a/include/llvm/Support/FileSystem.h
+++ b/include/llvm/Support/FileSystem.h
@@ -269,6 +269,14 @@ private:
 ///          platform specific error_code.
 error_code make_absolute(SmallVectorImpl<char> &path);
 
+/// @brief Normalize path separators in \a Path
+///
+/// If the path contains any '\' separators, they are transformed into '/'.
+/// This is particularly useful when cross-compiling Windows on Linux, but is
+/// safe to invoke on Windows, which accepts both characters as a path
+/// separator.
+error_code normalize_separators(SmallVectorImpl<char> &Path);
+
 /// @brief Create all the non-existent directories in path.
 ///
 /// @param path Directories to create.
diff --git a/lib/Support/Unix/Path.inc b/lib/Support/Unix/Path.inc
index 2b29baca738..500b7fecb74 100644
--- a/lib/Support/Unix/Path.inc
+++ b/lib/Support/Unix/Path.inc
@@ -272,6 +272,19 @@ error_code create_directory(const Twine &path, bool IgnoreExisting) {
   return error_code::success();
 }
 
+error_code normalize_separators(SmallVectorImpl<char> &Path) {
+  for (auto PI = Path.begin(), PE = Path.end(); PI < PE; ++PI) {
+    if (*PI == '\\') {
+      auto PN = PI + 1;
+      if (PN < PE && *PN == '\\')
+        ++PI; // increment once, the for loop will move over the escaped slash
+      else
+        *PI = '/';
+    }
+  }
+  return error_code::success();
+}
+
 // Note that we are using symbolic link because hard links are not supported by
 // all filesystems (SMB doesn't).
 error_code create_link(const Twine &to, const Twine &from) {
diff --git a/lib/Support/Windows/Path.inc b/lib/Support/Windows/Path.inc
index a555f3e794e..e59888e3858 100644
--- a/lib/Support/Windows/Path.inc
+++ b/lib/Support/Windows/Path.inc
@@ -158,6 +158,11 @@ error_code create_directory(const Twine &path, bool IgnoreExisting) {
   return error_code::success();
 }
 
+error_code normalize_separators(SmallVectorImpl<char> &Path) {
+  (void) Path;
+  return error_code::success();
+}
+
 // We can't use symbolic links for windows.
 error_code create_link(const Twine &to, const Twine &from) {
   // Get arguments.
diff --git a/unittests/Support/Path.cpp b/unittests/Support/Path.cpp
index 91e421d3827..b79d05505c4 100644
--- a/unittests/Support/Path.cpp
+++ b/unittests/Support/Path.cpp
@@ -620,4 +620,41 @@ TEST_F(FileSystemTest, FileMapping) {
   fs::mapped_file_region mfrrv(std::move(m));
   EXPECT_EQ(mfrrv.const_data(), Data);
 }
+
+TEST(Support, NormalizePath) {
+#if defined(LLVM_ON_WIN32)
+#define EXPECT_PATH_IS(path__, windows__, not_windows__)                        \
+  EXPECT_EQ(path__, windows__);
+#else
+#define EXPECT_PATH_IS(path__, windows__, not_windows__)                        \
+  EXPECT_EQ(path__, not_windows__);
+#endif
+
+  SmallString<64> Path1("a");
+  SmallString<64> Path2("a/b");
+  SmallString<64> Path3("a\\b");
+  SmallString<64> Path4("a\\\\b");
+  SmallString<64> Path5("\\a");
+  SmallString<64> Path6("a\\");
+
+  ASSERT_NO_ERROR(fs::normalize_separators(Path1));
+  EXPECT_PATH_IS(Path1, "a", "a");
+
+  ASSERT_NO_ERROR(fs::normalize_separators(Path2));
+  EXPECT_PATH_IS(Path2, "a/b", "a/b");
+
+  ASSERT_NO_ERROR(fs::normalize_separators(Path3));
+  EXPECT_PATH_IS(Path3, "a\\b", "a/b");
+
+  ASSERT_NO_ERROR(fs::normalize_separators(Path4));
+  EXPECT_PATH_IS(Path4, "a\\\\b", "a\\\\b");
+
+  ASSERT_NO_ERROR(fs::normalize_separators(Path5));
+  EXPECT_PATH_IS(Path5, "\\a", "/a");
+
+  ASSERT_NO_ERROR(fs::normalize_separators(Path6));
+  EXPECT_PATH_IS(Path6, "a\\", "a/");
+
+#undef EXPECT_PATH_IS
+}
 } // anonymous namespace