Fix a relatively nasty bug with fs::getPathFromOpenFD() on Windows. The GetFinalPathNameByHandle API does not behave as documented; if given a buffer that has enough space for the path but not the null terminator, the call will return the number of characters required *without* the null terminator (despite being documented otherwise) and it will not set GetLastError(). The result was that this function would return a bogus path and no error. Instead, ensure there is sufficient space for a null terminator (we already strip it off manually for compatibility with older versions of Windows).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@273195 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 33 insertions, 0 deletions

diff --git a/unittests/Support/Path.cpp b/unittests/Support/Path.cpp
index 705a90bd0a3..74b74ac4195 100644
--- a/unittests/Support/Path.cpp
+++ b/unittests/Support/Path.cpp
@@ -1024,6 +1024,39 @@ TEST_F(FileSystemTest, PathFromFD) {
   ::close(FileDescriptor);
 }
 
+TEST_F(FileSystemTest, PathFromFDWin32) {
+  // Create a temp file.
+  int FileDescriptor;
+  SmallString<64> TempPath;
+  ASSERT_NO_ERROR(
+    fs::createTemporaryFile("prefix", "temp", FileDescriptor, TempPath));
+
+  // Make sure it exists.
+  ASSERT_TRUE(sys::fs::exists(Twine(TempPath)));
+  
+  SmallVector<char, 8> ResultPath;
+  std::error_code ErrorCode =
+    fs::getPathFromOpenFD(FileDescriptor, ResultPath);
+
+  if (!ErrorCode) {
+    // Now that we know how much space is required for the path, create a path
+    // buffer with exactly enough space (sans null terminator, which should not
+    // be present), and call getPathFromOpenFD again to ensure that the API
+    // properly handles exactly-sized buffers.
+    SmallVector<char, 8> ExactSizedPath(ResultPath.size());
+    ErrorCode = fs::getPathFromOpenFD(FileDescriptor, ExactSizedPath);
+    ResultPath = ExactSizedPath;
+  }
+
+  if (!ErrorCode) {
+    fs::UniqueID D1, D2;
+    ASSERT_NO_ERROR(fs::getUniqueID(Twine(TempPath), D1));
+    ASSERT_NO_ERROR(fs::getUniqueID(Twine(ResultPath), D2));
+    ASSERT_EQ(D1, D2);
+  }
+  ::close(FileDescriptor);
+}
+
 TEST_F(FileSystemTest, OpenFileForRead) {
   // Create a temp file.
   int FileDescriptor;