[Support] [Windows] Convert paths to the preferred form

This normalizes most paths (except ones input from the user as command
line arguments) into the preferred form, if `real_style()` evaluates to
`windows_forward`.

Differential Revision: https://reviews.llvm.org/D111880

llvm/lib/Support/Windows/Path.inc

@@ -74,6 +74,11 @@ std::error_code widenPath(const Twine &Path8, SmallVectorImpl<wchar_t> &Path16,
   SmallString<MAX_PATH> Path8Str;
   Path8.toVector(Path8Str);
 
+  // If the path is a long path, mangled into forward slashes, normalize
+  // back to backslashes here.
+  if (Path8Str.startswith("//?/"))
+    llvm::sys::path::native(Path8Str, path::Style::windows_backslash);
+
   if (std::error_code EC = UTF8ToUTF16(Path8Str, Path16))
     return EC;
 
@@ -100,8 +105,10 @@ std::error_code widenPath(const Twine &Path8, SmallVectorImpl<wchar_t> &Path16,
   }
 
   // Remove '.' and '..' because long paths treat these as real path components.
+  // Explicitly use the backslash form here, as we're prepending the \\?\
+  // prefix.
   llvm::sys::path::native(Path8Str, path::Style::windows);
-  llvm::sys::path::remove_dots(Path8Str, true);
+  llvm::sys::path::remove_dots(Path8Str, true, path::Style::windows);
 
   const StringRef RootName = llvm::sys::path::root_name(Path8Str);
   assert(!RootName.empty() &&
@@ -145,6 +152,7 @@ std::string getMainExecutable(const char *argv0, void *MainExecAddr) {
   if (UTF16ToUTF8(PathName.data(), PathName.size(), PathNameUTF8))
     return "";
 
+  llvm::sys::path::make_preferred(PathNameUTF8);
   return std::string(PathNameUTF8.data());
 }
 
@@ -207,7 +215,13 @@ std::error_code current_path(SmallVectorImpl<char> &result) {
   // On success, GetCurrentDirectoryW returns the number of characters not
   // including the null-terminator.
   cur_path.set_size(len);
-  return UTF16ToUTF8(cur_path.begin(), cur_path.size(), result);
+
+  if (std::error_code EC =
+          UTF16ToUTF8(cur_path.begin(), cur_path.size(), result))
+    return EC;
+
+  llvm::sys::path::make_preferred(result);
+  return std::error_code();
 }
 
 std::error_code set_current_path(const Twine &path) {
@@ -388,7 +402,11 @@ static std::error_code realPathFromHandle(HANDLE H,
   }
 
   // Convert the result from UTF-16 to UTF-8.
-  return UTF16ToUTF8(Data, CountChars, RealPath);
+  if (std::error_code EC = UTF16ToUTF8(Data, CountChars, RealPath))
+    return EC;
+
+  llvm::sys::path::make_preferred(RealPath);
+  return std::error_code();
 }
 
 std::error_code is_local(int FD, bool &Result) {
@@ -1407,6 +1425,8 @@ static bool getKnownFolderPath(KNOWNFOLDERID folderId,
 
   bool ok = !UTF16ToUTF8(path, ::wcslen(path), result);
   ::CoTaskMemFree(path);
+  if (ok)
+    llvm::sys::path::make_preferred(result);
   return ok;
 }
 
@@ -1467,6 +1487,7 @@ void system_temp_directory(bool ErasedOnReboot, SmallVectorImpl<char> &Result) {
   // Fall back to a system default.
   const char *DefaultResult = "C:\\Temp";
   Result.append(DefaultResult, DefaultResult + strlen(DefaultResult));
+  llvm::sys::path::make_preferred(Result);
 }
 } // end namespace path
 

llvm/lib/Support/Windows/Process.inc

@@ -261,6 +261,7 @@ windows::GetCommandLineArguments(SmallVectorImpl<const char *> &Args,
   EC = GetExecutableName(Filename);
   if (EC)
     return EC;
+  sys::path::make_preferred(Arg0);
   sys::path::append(Arg0, Filename);
   Args[0] = Saver.save(Arg0).data();
   return std::error_code();

llvm/lib/Support/Windows/Program.inc

@@ -103,6 +103,7 @@ ErrorOr<std::string> sys::findProgramByName(StringRef Name,
   if (U8Result.empty())
     return mapWindowsError(::GetLastError());
 
+  llvm::sys::path::make_preferred(U8Result);
   return std::string(U8Result.begin(), U8Result.end());
 }
 

llvm/unittests/Support/CommandLineTest.cpp

@@ -1112,6 +1112,11 @@ TEST(CommandLineTest, PositionalEatArgsError) {
 }
 
 #ifdef _WIN32
+void checkSeparators(StringRef Path) {
+  char UndesiredSeparator = sys::path::get_separator()[0] == '/' ? '\\' : '/';
+  ASSERT_EQ(Path.find(UndesiredSeparator), StringRef::npos);
+}
+
 TEST(CommandLineTest, GetCommandLineArguments) {
   int argc = __argc;
   char **argv = __argv;
@@ -1121,6 +1126,7 @@ TEST(CommandLineTest, GetCommandLineArguments) {
 
   EXPECT_EQ(llvm::sys::path::is_absolute(argv[0]),
             llvm::sys::path::is_absolute(__argv[0]));
+  checkSeparators(argv[0]);
 
   EXPECT_TRUE(
       llvm::sys::path::filename(argv[0]).equals_insensitive("supporttests.exe"))

llvm/unittests/Support/Path.cpp

@@ -64,6 +64,13 @@ using namespace llvm::sys;
 
 namespace {
 
+void checkSeparators(StringRef Path) {
+#ifdef _WIN32
+  char UndesiredSeparator = sys::path::get_separator()[0] == '/' ? '\\' : '/';
+  ASSERT_EQ(Path.find(UndesiredSeparator), StringRef::npos);
+#endif
+}
+
 struct FileDescriptorCloser {
   explicit FileDescriptorCloser(int FD) : FD(FD) {}
   ~FileDescriptorCloser() { ::close(FD); }
@@ -436,6 +443,9 @@ std::string getEnvWin(const wchar_t *Var) {
     ArrayRef<char> ref{reinterpret_cast<char const *>(path),
                        pathLen * sizeof(wchar_t)};
     convertUTF16ToUTF8String(ref, expected);
+    SmallString<32> Buf(expected);
+    path::make_preferred(Buf);
+    expected.assign(Buf.begin(), Buf.end());
   }
   return expected;
 }
@@ -583,9 +593,15 @@ TEST(Support, TempDirectory) {
 #ifdef _WIN32
 static std::string path2regex(std::string Path) {
   size_t Pos = 0;
+  bool Forward = path::get_separator()[0] == '/';
   while ((Pos = Path.find('\\', Pos)) != std::string::npos) {
-    Path.replace(Pos, 1, "\\\\");
-    Pos += 2;
+    if (Forward) {
+      Path.replace(Pos, 1, "/");
+      Pos += 1;
+    } else {
+      Path.replace(Pos, 1, "\\\\");
+      Pos += 2;
+    }
   }
   return Path;
 }
@@ -732,10 +748,12 @@ TEST_F(FileSystemTest, RealPath) {
   // how we specified it.  Make sure to compare against the real_path of the
   // TestDirectory, and not just the value of TestDirectory.
   ASSERT_NO_ERROR(fs::real_path(TestDirectory, RealBase));
+  checkSeparators(RealBase);
   path::native(Twine(RealBase) + "/test1/test2", Expected);
 
   ASSERT_NO_ERROR(fs::real_path(
       Twine(TestDirectory) + "/././test1/../test1/test2/./test3/..", Actual));
+  checkSeparators(Actual);
 
   EXPECT_EQ(Expected, Actual);
 
@@ -744,7 +762,9 @@ TEST_F(FileSystemTest, RealPath) {
   // This can fail if $HOME is not set and getpwuid fails.
   bool Result = llvm::sys::path::home_directory(HomeDir);
   if (Result) {
+    checkSeparators(HomeDir);
     ASSERT_NO_ERROR(fs::real_path(HomeDir, Expected));
+    checkSeparators(Expected);
     ASSERT_NO_ERROR(fs::real_path("~", Actual, true));
     EXPECT_EQ(Expected, Actual);
     ASSERT_NO_ERROR(fs::real_path("~/", Actual, true));
@@ -2266,6 +2286,30 @@ TEST_F(FileSystemTest, widenPath) {
 
   ASSERT_NO_ERROR(windows::widenPath(Input, Result));
   EXPECT_EQ(Result, Expected);
+  // Pass a path with forward slashes, check that it ends up with
+  // backslashes when widened with the long path prefix.
+  SmallString<MAX_PATH + 16> InputForward(Input);
+  path::make_preferred(InputForward, path::Style::windows_slash);
+  ASSERT_NO_ERROR(windows::widenPath(InputForward, Result));
+  EXPECT_EQ(Result, Expected);
+
+  // Pass a path which has the long path prefix prepended originally, but
+  // which is short enough to not require the long path prefix. If such a
+  // path is passed with forward slashes, make sure it gets normalized to
+  // backslashes.
+  SmallString<MAX_PATH + 16> PrefixedPath("\\\\?\\C:\\foldername");
+  ASSERT_NO_ERROR(windows::UTF8ToUTF16(PrefixedPath, Expected));
+  // Mangle the input to forward slashes.
+  path::make_preferred(PrefixedPath, path::Style::windows_slash);
+  ASSERT_NO_ERROR(windows::widenPath(PrefixedPath, Result));
+  EXPECT_EQ(Result, Expected);
+
+  // A short path with an inconsistent prefix is passed through as-is; this
+  // is a degenerate case that we currently don't care about handling.
+  PrefixedPath.assign("/\\?/C:/foldername");
+  ASSERT_NO_ERROR(windows::UTF8ToUTF16(PrefixedPath, Expected));
+  ASSERT_NO_ERROR(windows::widenPath(PrefixedPath, Result));
+  EXPECT_EQ(Result, Expected);
 
   // Test that UNC paths are handled correctly.
   const std::string ShareName("\\\\sharename\\");

llvm/unittests/Support/ProgramTest.cpp

@@ -110,17 +110,26 @@ protected:
 };
 
 #ifdef _WIN32
+void checkSeparators(StringRef Path) {
+  char UndesiredSeparator = sys::path::get_separator()[0] == '/' ? '\\' : '/';
+  ASSERT_EQ(Path.find(UndesiredSeparator), StringRef::npos);
+}
+
 TEST_F(ProgramEnvTest, CreateProcessLongPath) {
   if (getenv("LLVM_PROGRAM_TEST_LONG_PATH"))
     exit(0);
 
   // getMainExecutable returns an absolute path; prepend the long-path prefix.
-  std::string MyAbsExe =
-      sys::fs::getMainExecutable(TestMainArgv0, &ProgramTestStringArg1);
+  SmallString<128> MyAbsExe(
+      sys::fs::getMainExecutable(TestMainArgv0, &ProgramTestStringArg1));
+  checkSeparators(MyAbsExe);
+  // Force a path with backslashes, when we are going to prepend the \\?\
+  // prefix.
+  sys::path::native(MyAbsExe, sys::path::Style::windows_backslash);
   std::string MyExe;
   if (!StringRef(MyAbsExe).startswith("\\\\?\\"))
     MyExe.append("\\\\?\\");
-  MyExe.append(MyAbsExe);
+  MyExe.append(std::string(MyAbsExe.begin(), MyAbsExe.end()));
 
   StringRef ArgV[] = {MyExe,
                       "--gtest_filter=ProgramEnvTest.CreateProcessLongPath"};