[Lldb-commits] [lldb] [lldb][windows] prevent IOHandlerProcessSTDIOWindows from consuming non text inputs (PR #175812)

[Charles Zablit via lldb-commits]

https://github.com/charles-zablit updated https://github.com/llvm/llvm-project/pull/175812

>From ca113a51b42d08382e0a9b6dd0636eba9f0d6ab4 Mon Sep 17 00:00:00 2001
From: Charles Zablit <c_zablit at apple.com>
Date: Tue, 13 Jan 2026 18:54:43 +0000
Subject: [PATCH 1/3] [lldb][windows] prevent IOHandlerProcessSTDIOWindows from
 consuming non text inputs

---
 .../Process/Windows/Common/ProcessWindows.cpp   | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/lldb/source/Plugins/Process/Windows/Common/ProcessWindows.cpp b/lldb/source/Plugins/Process/Windows/Common/ProcessWindows.cpp
index 127dd0f59e9ae..72043d16313cd 100644
--- a/lldb/source/Plugins/Process/Windows/Common/ProcessWindows.cpp
+++ b/lldb/source/Plugins/Process/Windows/Common/ProcessWindows.cpp
@@ -981,6 +981,9 @@ class IOHandlerProcessSTDIOWindows : public IOHandler {
     HANDLE hInterrupt = (HANDLE)_get_osfhandle(m_pipe.GetReadFileDescriptor());
     HANDLE waitHandles[2] = {hStdin, hInterrupt};
 
+    DWORD consoleMode;
+    bool isConsole = GetConsoleMode(hStdin, &consoleMode) != 0;
+
     while (true) {
       {
         std::lock_guard<std::mutex> guard(m_mutex);
@@ -993,6 +996,20 @@ class IOHandlerProcessSTDIOWindows : public IOHandler {
       case WAIT_FAILED:
         goto exit_loop;
       case WAIT_OBJECT_0: {
+        if (isConsole) {
+          INPUT_RECORD inputRecord;
+          DWORD numRead = 0;
+          if (!PeekConsoleInput(hStdin, &inputRecord, 1, &numRead) ||
+              numRead == 0)
+            goto exit_loop;
+          // We only care about text input. Ignore all non text input events and
+          // let other IOHandlers handle them.
+          if (inputRecord.EventType != KEY_EVENT ||
+              !inputRecord.Event.KeyEvent.bKeyDown ||
+              inputRecord.Event.KeyEvent.uChar.AsciiChar == 0)
+            break;
+        }
+
         char ch = 0;
         DWORD read = 0;
         if (!ReadFile(hStdin, &ch, 1, &read, nullptr) || read != 1)

>From 0fa56fa8a08ea20f031baddce32d85f4bef20a41 Mon Sep 17 00:00:00 2001
From: Charles Zablit <c_zablit at apple.com>
Date: Mon, 19 Jan 2026 13:50:09 +0000
Subject: [PATCH 2/3] consume non text input

---
 .../Process/Windows/Common/ProcessWindows.cpp | 28 +++++++++++--------
 1 file changed, 17 insertions(+), 11 deletions(-)

diff --git a/lldb/source/Plugins/Process/Windows/Common/ProcessWindows.cpp b/lldb/source/Plugins/Process/Windows/Common/ProcessWindows.cpp
index 72043d16313cd..ed02f243a5445 100644
--- a/lldb/source/Plugins/Process/Windows/Common/ProcessWindows.cpp
+++ b/lldb/source/Plugins/Process/Windows/Common/ProcessWindows.cpp
@@ -997,17 +997,23 @@ class IOHandlerProcessSTDIOWindows : public IOHandler {
         goto exit_loop;
       case WAIT_OBJECT_0: {
         if (isConsole) {
-          INPUT_RECORD inputRecord;
-          DWORD numRead = 0;
-          if (!PeekConsoleInput(hStdin, &inputRecord, 1, &numRead) ||
-              numRead == 0)
-            goto exit_loop;
-          // We only care about text input. Ignore all non text input events and
-          // let other IOHandlers handle them.
-          if (inputRecord.EventType != KEY_EVENT ||
-              !inputRecord.Event.KeyEvent.bKeyDown ||
-              inputRecord.Event.KeyEvent.uChar.AsciiChar == 0)
-            break;
+          while (true) {
+            INPUT_RECORD inputRecord;
+            DWORD numRead = 0;
+            if (!PeekConsoleInput(hStdin, &inputRecord, 1, &numRead) ||
+                numRead == 0)
+              goto exit_loop;
+
+            // We only care about text input. Consume all non text input events before letting ReadFile handle text input.
+            if (inputRecord.EventType == KEY_EVENT &&
+                inputRecord.Event.KeyEvent.bKeyDown &&
+                inputRecord.Event.KeyEvent.uChar.AsciiChar != 0)
+              break;
+
+            if (!ReadConsoleInput(hStdin, &inputRecord, 1, &numRead) ||
+                numRead == 0)
+              goto exit_loop;
+          }
         }
 
         char ch = 0;

>From 275e21f2179b313337d56f0ada62f6fb70dd767d Mon Sep 17 00:00:00 2001
From: Charles Zablit <c_zablit at apple.com>
Date: Mon, 19 Jan 2026 13:57:50 +0000
Subject: [PATCH 3/3] fix formatting

---
 lldb/source/Plugins/Process/Windows/Common/ProcessWindows.cpp | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/lldb/source/Plugins/Process/Windows/Common/ProcessWindows.cpp b/lldb/source/Plugins/Process/Windows/Common/ProcessWindows.cpp
index ed02f243a5445..0717f4f50a02a 100644
--- a/lldb/source/Plugins/Process/Windows/Common/ProcessWindows.cpp
+++ b/lldb/source/Plugins/Process/Windows/Common/ProcessWindows.cpp
@@ -1004,7 +1004,8 @@ class IOHandlerProcessSTDIOWindows : public IOHandler {
                 numRead == 0)
               goto exit_loop;
 
-            // We only care about text input. Consume all non text input events before letting ReadFile handle text input.
+            // We only care about text input. Consume all non text input events
+            // before letting ReadFile handle text input.
             if (inputRecord.EventType == KEY_EVENT &&
                 inputRecord.Event.KeyEvent.bKeyDown &&
                 inputRecord.Event.KeyEvent.uChar.AsciiChar != 0)