[Lldb-commits] [lldb] [lldb][windows] fix command source hitting EOF (PR #194950)

[Charles Zablit via lldb-commits]

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@@ -356,6 +356,15 @@ FILE *NativeFile::GetStream() {
         if (m_stream) {
           m_own_stream = true;
           m_own_descriptor = false;
+#ifdef _WIN32
+          // On Windows, the first fgets() fills the C-runtime's internal
+          // buffer with one large OS read, leaving the underlying fd at EOF.
+          // Code that later opens the same fd then immediately hits EOF.
+          // Disabling buffering here, before any I/O touches the stream, keeps
+          // the fd in sync with what has been logically consumed.
+          if ((m_options & OpenOptionsModeMask) == eOpenOptionReadOnly)
+            setvbuf(m_stream, nullptr, _IONBF, 0);
+#endif
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charles-zablit wrote:

> What exactly is your concern? If we design it right, parts of the implementation will remain in Common and only the platform specific parts are moved out.

You are right, I was thinking of `ProcessLauncher` and `NativeProcessWindows`, but they are very different.

I opened a PR to make the refactor here:
- https://github.com/llvm/llvm-project/pull/196293

https://github.com/llvm/llvm-project/pull/194950