[Lldb-commits] [lldb] [lldb-dap][windows] don't use the ConPTY in internalConsole mode (PR #186472)
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lldb-commits at lists.llvm.org
Fri Mar 13 10:53:22 PDT 2026
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-lldb
Author: Charles Zablit (charles-zablit)
<details>
<summary>Changes</summary>
In `internalConsole` mode (especially in VSCode), lldb-dap should not use the ConPTY to read the process' output. This is because the internalConsole is not a real terminal, there is no reason to use terminal emulation, which will add arbitrary line returns to the output.
Instead, this patch introduces the `eLaunchFlagUsePipes` flag in ProcessLaunchInfo which tells ProcessLaunchWindows to use regular pipes instead of a ConPTY to get the stdin and stdout of the debuggee.
The result is that output which is supposed to be on a single line is properly rendered:
# Before
<img width="2214" height="672" alt="Screenshot 2026-03-13 at 17 07 35" src="https://github.com/user-attachments/assets/26292d11-2288-46ee-a6d2-0b66bfa41288" />
# After
<img width="2215" height="689" alt="Screenshot 2026-03-13 at 17 12 39" src="https://github.com/user-attachments/assets/c9cad9af-b1ce-4c7b-91d5-f684e48e64ca" />
---
Full diff: https://github.com/llvm/llvm-project/pull/186472.diff
8 Files Affected:
- (modified) lldb/include/lldb/Host/ProcessLaunchInfo.h (+9-1)
- (modified) lldb/include/lldb/Host/windows/PseudoConsole.h (+26-1)
- (modified) lldb/include/lldb/lldb-enumerations.h (+4)
- (modified) lldb/source/Host/common/ProcessLaunchInfo.cpp (+8)
- (modified) lldb/source/Host/windows/ProcessLauncherWindows.cpp (+32-6)
- (modified) lldb/source/Host/windows/PseudoConsole.cpp (+62)
- (modified) lldb/source/Target/Target.cpp (+13-2)
- (modified) lldb/tools/lldb-dap/Handler/RequestHandler.cpp (+4)
``````````diff
diff --git a/lldb/include/lldb/Host/ProcessLaunchInfo.h b/lldb/include/lldb/Host/ProcessLaunchInfo.h
index 7801662b244ad..365d1952d173f 100644
--- a/lldb/include/lldb/Host/ProcessLaunchInfo.h
+++ b/lldb/include/lldb/Host/ProcessLaunchInfo.h
@@ -64,6 +64,14 @@ class ProcessLaunchInfo : public ProcessInfo {
// but stderr doesn't, then only stderr will be redirected to a pty.)
llvm::Error SetUpPtyRedirection();
+#ifdef _WIN32
+ // Redirect stdin/stdout/stderr to anonymous pipes instead of a ConPTY.
+ // Used when terminal emulation is not needed (e.g. lldb-dap internalConsole).
+ llvm::Error SetUpPipeRedirection();
+#endif
+
+ bool HasPTY() const { return m_pty != nullptr; }
+
size_t GetNumFileActions() const { return m_file_actions.size(); }
const FileAction *GetFileActionAtIndex(size_t idx) const;
@@ -138,7 +146,7 @@ class ProcessLaunchInfo : public ProcessInfo {
#ifdef _WIN32
if (!m_pty)
return false;
- return GetPTY().GetPseudoTerminalHandle() != ((HANDLE)(long long)-1) &&
+ return GetPTY().GetMode() != PseudoConsole::Mode::None &&
GetNumFileActions() == 0;
#else
return true;
diff --git a/lldb/include/lldb/Host/windows/PseudoConsole.h b/lldb/include/lldb/Host/windows/PseudoConsole.h
index a1967fc85188c..7d7e00cbb1d7a 100644
--- a/lldb/include/lldb/Host/windows/PseudoConsole.h
+++ b/lldb/include/lldb/Host/windows/PseudoConsole.h
@@ -22,6 +22,8 @@ namespace lldb_private {
class PseudoConsole {
public:
+ enum Mode { ConPTY, Pipe, None };
+
PseudoConsole() = default;
~PseudoConsole();
@@ -40,14 +42,25 @@ class PseudoConsole {
/// otherwise.
llvm::Error OpenPseudoConsole();
+ /// Creates a pair of anonymous pipes to use for stdio instead of a ConPTY.
+ ///
+ /// \return
+ /// An llvm::Error if the pipes could not be created.
+ llvm::Error OpenAnonymousPipes();
+
/// Closes the ConPTY and invalidates its handle, without closing the STDIN
/// and STDOUT pipes. Closing the ConPTY signals EOF to any process currently
/// attached to it.
void Close();
- /// Closes the STDIN and STDOUT pipe handles and invalidates them
+ /// Closes the STDIN and STDOUT pipe handles and invalidates them.
void ClosePipes();
+ /// Closes the child-side pipe handles (stdin read end and stdout/stderr write
+ /// end) that were passed to CreateProcessW. Must be called after a successful
+ /// CreateProcessW to avoid keeping the pipes alive indefinitely.
+ void CloseChildHandles();
+
/// Returns whether the ConPTY and its pipes are currently open and valid.
bool IsConnected() const;
@@ -78,6 +91,14 @@ class PseudoConsole {
/// invalid.
HANDLE GetSTDINHandle() const { return m_conpty_input; };
+ /// The child-side stdin read HANDLE (pipe mode only).
+ HANDLE GetChildStdinHandle() const { return m_pipe_child_stdin; };
+
+ /// The child-side stdout/stderr write HANDLE (pipe mode only).
+ HANDLE GetChildStdoutHandle() const { return m_pipe_child_stdout; };
+
+ Mode GetMode() const { return m_mode; };
+
/// Drains initialization sequences from the ConPTY output pipe.
///
/// When a process first attaches to a ConPTY, Windows emits VT100/ANSI escape
@@ -112,6 +133,10 @@ class PseudoConsole {
HANDLE m_conpty_handle = ((HANDLE)(long long)-1);
HANDLE m_conpty_output = ((HANDLE)(long long)-1);
HANDLE m_conpty_input = ((HANDLE)(long long)-1);
+ // Pipe mode: child-side handles passed to CreateProcessW, closed after launch
+ HANDLE m_pipe_child_stdin = ((HANDLE)(long long)-1);
+ HANDLE m_pipe_child_stdout = ((HANDLE)(long long)-1);
+ Mode m_mode = Mode::None;
std::mutex m_mutex{};
std::condition_variable m_cv{};
std::atomic<bool> m_stopping = false;
diff --git a/lldb/include/lldb/lldb-enumerations.h b/lldb/include/lldb/lldb-enumerations.h
index d2600d0a6ce44..11b7808bb1b61 100644
--- a/lldb/include/lldb/lldb-enumerations.h
+++ b/lldb/include/lldb/lldb-enumerations.h
@@ -132,6 +132,10 @@ FLAGS_ENUM(LaunchFlags){
///< permissions but instead inherit them from its parent.
eLaunchFlagMemoryTagging =
(1u << 13), ///< Launch process with memory tagging explicitly enabled.
+ eLaunchFlagUsePipes =
+ (1u << 14), ///< Use anonymous pipes for stdio instead of a ConPTY on
+ ///< Windows. Useful when terminal emulation is not needed
+ ///< (e.g. lldb-dap internalConsole mode).
};
/// Thread Run Modes.
diff --git a/lldb/source/Host/common/ProcessLaunchInfo.cpp b/lldb/source/Host/common/ProcessLaunchInfo.cpp
index 2f67a417996ac..9f87e6a783adc 100644
--- a/lldb/source/Host/common/ProcessLaunchInfo.cpp
+++ b/lldb/source/Host/common/ProcessLaunchInfo.cpp
@@ -242,6 +242,14 @@ llvm::Error ProcessLaunchInfo::SetUpPtyRedirection() {
#endif
}
+#ifdef _WIN32
+llvm::Error ProcessLaunchInfo::SetUpPipeRedirection() {
+ if (!m_pty)
+ m_pty = std::make_shared<PTY>();
+ return m_pty->OpenAnonymousPipes();
+}
+#endif
+
bool ProcessLaunchInfo::ConvertArgumentsForLaunchingInShell(
Status &error, bool will_debug, bool first_arg_is_full_shell_command,
uint32_t num_resumes) {
diff --git a/lldb/source/Host/windows/ProcessLauncherWindows.cpp b/lldb/source/Host/windows/ProcessLauncherWindows.cpp
index fb091eb75d9b8..11c9d6ec30925 100644
--- a/lldb/source/Host/windows/ProcessLauncherWindows.cpp
+++ b/lldb/source/Host/windows/ProcessLauncherWindows.cpp
@@ -130,7 +130,9 @@ ProcessLauncherWindows::LaunchProcess(const ProcessLaunchInfo &launch_info,
startupinfoex.StartupInfo.cb = sizeof(STARTUPINFOEXW);
startupinfoex.StartupInfo.dwFlags |= STARTF_USESTDHANDLES;
- bool use_pty = launch_info.ShouldUsePTY();
+ PseudoConsole::Mode pty_mode = launch_info.ShouldUsePTY()
+ ? launch_info.GetPTY().GetMode()
+ : PseudoConsole::Mode::None;
HANDLE stdin_handle = GetStdioHandle(launch_info, STDIN_FILENO);
HANDLE stdout_handle = GetStdioHandle(launch_info, STDOUT_FILENO);
@@ -152,13 +154,31 @@ ProcessLauncherWindows::LaunchProcess(const ProcessLaunchInfo &launch_info,
ProcThreadAttributeList attributelist = std::move(*attributelist_or_err);
std::vector<HANDLE> inherited_handles;
- if (use_pty) {
+ switch (pty_mode) {
+ case PseudoConsole::Mode::ConPTY: {
HPCON hPC = launch_info.GetPTY().GetPseudoTerminalHandle();
if (auto err = attributelist.SetupPseudoConsole(hPC)) {
error = Status::FromError(std::move(err));
return HostProcess();
}
- } else {
+ break;
+ }
+ case PseudoConsole::Mode::Pipe: {
+ PseudoConsole &pty = launch_info.GetPTY();
+ startupinfoex.StartupInfo.hStdInput = pty.GetChildStdinHandle();
+ startupinfoex.StartupInfo.hStdOutput = pty.GetChildStdoutHandle();
+ startupinfoex.StartupInfo.hStdError = pty.GetChildStdoutHandle();
+ inherited_handles = {pty.GetChildStdinHandle(), pty.GetChildStdoutHandle()};
+ if (!UpdateProcThreadAttribute(
+ startupinfoex.lpAttributeList, 0, PROC_THREAD_ATTRIBUTE_HANDLE_LIST,
+ inherited_handles.data(), inherited_handles.size() * sizeof(HANDLE),
+ nullptr, nullptr)) {
+ error = Status(::GetLastError(), eErrorTypeWin32);
+ return HostProcess();
+ }
+ break;
+ }
+ case PseudoConsole::Mode::None: {
auto inherited_handles_or_err =
GetInheritedHandles(startupinfoex, &launch_info, stdout_handle,
stderr_handle, stdin_handle);
@@ -167,6 +187,8 @@ ProcessLauncherWindows::LaunchProcess(const ProcessLaunchInfo &launch_info,
return HostProcess();
}
inherited_handles = std::move(*inherited_handles_or_err);
+ break;
+ }
}
const char *hide_console_var =
@@ -182,7 +204,8 @@ ProcessLauncherWindows::LaunchProcess(const ProcessLaunchInfo &launch_info,
if (launch_info.GetFlags().Test(eLaunchFlagDebug))
flags |= DEBUG_ONLY_THIS_PROCESS;
- if (launch_info.GetFlags().Test(eLaunchFlagDisableSTDIO) || use_pty)
+ if (launch_info.GetFlags().Test(eLaunchFlagDisableSTDIO) ||
+ pty_mode != PseudoConsole::Mode::None)
flags &= ~CREATE_NEW_CONSOLE;
std::vector<wchar_t> environment =
@@ -210,8 +233,9 @@ ProcessLauncherWindows::LaunchProcess(const ProcessLaunchInfo &launch_info,
BOOL result = ::CreateProcessW(
wexecutable.c_str(), pwcommandLine, NULL, NULL,
- /*bInheritHandles=*/!inherited_handles.empty() || use_pty, flags,
- environment.data(),
+ /*bInheritHandles=*/!inherited_handles.empty() ||
+ pty_mode != PseudoConsole::Mode::None,
+ flags, environment.data(),
wworkingDirectory.size() == 0 ? NULL : wworkingDirectory.c_str(),
reinterpret_cast<STARTUPINFOW *>(&startupinfoex), &pi);
@@ -226,6 +250,8 @@ ProcessLauncherWindows::LaunchProcess(const ProcessLaunchInfo &launch_info,
// Do not call CloseHandle on pi.hProcess, since we want to pass that back
// through the HostProcess.
::CloseHandle(pi.hThread);
+ if (pty_mode == PseudoConsole::Mode::Pipe)
+ launch_info.GetPTY().CloseChildHandles();
}
if (!result)
diff --git a/lldb/source/Host/windows/PseudoConsole.cpp b/lldb/source/Host/windows/PseudoConsole.cpp
index b8b74091fe474..fed2336a191f8 100644
--- a/lldb/source/Host/windows/PseudoConsole.cpp
+++ b/lldb/source/Host/windows/PseudoConsole.cpp
@@ -126,6 +126,7 @@ llvm::Error PseudoConsole::OpenPseudoConsole() {
m_conpty_handle = hPC;
m_conpty_output = hOutputRead;
m_conpty_input = hInputWrite;
+ m_mode = Mode::ConPTY;
if (auto error = DrainInitSequences()) {
Log *log = GetLog(LLDBLog::Host);
@@ -137,6 +138,9 @@ llvm::Error PseudoConsole::OpenPseudoConsole() {
}
bool PseudoConsole::IsConnected() const {
+ if (m_mode == Mode::Pipe)
+ return m_conpty_input != INVALID_HANDLE_VALUE &&
+ m_conpty_output != INVALID_HANDLE_VALUE;
return m_conpty_handle != INVALID_HANDLE_VALUE &&
m_conpty_input != INVALID_HANDLE_VALUE &&
m_conpty_output != INVALID_HANDLE_VALUE;
@@ -162,6 +166,64 @@ void PseudoConsole::ClosePipes() {
m_conpty_output = INVALID_HANDLE_VALUE;
}
+void PseudoConsole::CloseChildHandles() {
+ if (m_pipe_child_stdin != INVALID_HANDLE_VALUE)
+ CloseHandle(m_pipe_child_stdin);
+ if (m_pipe_child_stdout != INVALID_HANDLE_VALUE)
+ CloseHandle(m_pipe_child_stdout);
+
+ m_pipe_child_stdin = INVALID_HANDLE_VALUE;
+ m_pipe_child_stdout = INVALID_HANDLE_VALUE;
+}
+
+llvm::Error PseudoConsole::OpenAnonymousPipes() {
+ SECURITY_ATTRIBUTES sa = {sizeof(SECURITY_ATTRIBUTES), NULL, TRUE};
+ HANDLE hStdinRead = INVALID_HANDLE_VALUE;
+ HANDLE hStdinWrite = INVALID_HANDLE_VALUE;
+ if (!CreatePipe(&hStdinRead, &hStdinWrite, &sa, 0))
+ return llvm::errorCodeToError(
+ std::error_code(GetLastError(), std::system_category()));
+ // Parent write end must not be inherited by the child.
+ SetHandleInformation(hStdinWrite, HANDLE_FLAG_INHERIT, 0);
+
+ wchar_t pipe_name[MAX_PATH];
+ swprintf(pipe_name, MAX_PATH, L"\\\\.\\pipe\\pipes-lldb-%d-%p",
+ GetCurrentProcessId(), this);
+
+ HANDLE hStdoutRead =
+ CreateNamedPipeW(pipe_name, PIPE_ACCESS_INBOUND | FILE_FLAG_OVERLAPPED,
+ PIPE_TYPE_BYTE | PIPE_WAIT, 1, 4096, 4096, 0, NULL);
+ if (hStdoutRead == INVALID_HANDLE_VALUE) {
+ CloseHandle(hStdinRead);
+ CloseHandle(hStdinWrite);
+ return llvm::errorCodeToError(
+ std::error_code(GetLastError(), std::system_category()));
+ }
+
+ SECURITY_ATTRIBUTES child_security_attributes = {sizeof(SECURITY_ATTRIBUTES),
+ NULL, TRUE};
+ HANDLE hStdoutWrite =
+ CreateFileW(pipe_name, GENERIC_WRITE, 0, &child_security_attributes,
+ OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);
+ if (hStdoutWrite == INVALID_HANDLE_VALUE) {
+ CloseHandle(hStdinRead);
+ CloseHandle(hStdinWrite);
+ CloseHandle(hStdoutRead);
+ return llvm::errorCodeToError(
+ std::error_code(GetLastError(), std::system_category()));
+ }
+
+ DWORD mode = PIPE_NOWAIT;
+ SetNamedPipeHandleState(hStdoutRead, &mode, NULL, NULL);
+
+ m_conpty_input = hStdinWrite;
+ m_conpty_output = hStdoutRead;
+ m_pipe_child_stdin = hStdinRead;
+ m_pipe_child_stdout = hStdoutWrite;
+ m_mode = Mode::Pipe;
+ return llvm::Error::success();
+}
+
llvm::Error PseudoConsole::DrainInitSequences() {
STARTUPINFOEXW startupinfoex = {};
startupinfoex.StartupInfo.cb = sizeof(STARTUPINFOEXW);
diff --git a/lldb/source/Target/Target.cpp b/lldb/source/Target/Target.cpp
index 9c8124a15333b..939c848395730 100644
--- a/lldb/source/Target/Target.cpp
+++ b/lldb/source/Target/Target.cpp
@@ -3859,8 +3859,19 @@ void Target::FinalizeFileActions(ProcessLaunchInfo &info) {
}
if (default_to_use_pty) {
- llvm::Error Err = info.SetUpPtyRedirection();
- LLDB_LOG_ERROR(log, std::move(Err), "SetUpPtyRedirection failed: {0}");
+#ifdef _WIN32
+ if (info.GetFlags().Test(eLaunchFlagUsePipes)) {
+ llvm::Error Err = info.SetUpPipeRedirection();
+ LLDB_LOG_ERROR(log, std::move(Err),
+ "SetUpPipeRedirection failed: {0}");
+ } else {
+#endif
+ llvm::Error Err = info.SetUpPtyRedirection();
+ LLDB_LOG_ERROR(log, std::move(Err),
+ "SetUpPtyRedirection failed: {0}");
+#ifdef _WIN32
+ }
+#endif
}
}
}
diff --git a/lldb/tools/lldb-dap/Handler/RequestHandler.cpp b/lldb/tools/lldb-dap/Handler/RequestHandler.cpp
index 5e8c2163c838f..f7aad21c0be41 100644
--- a/lldb/tools/lldb-dap/Handler/RequestHandler.cpp
+++ b/lldb/tools/lldb-dap/Handler/RequestHandler.cpp
@@ -223,6 +223,10 @@ llvm::Error BaseRequestHandler::LaunchProcess(
SetLaunchFlag(flags, arguments.disableASLR, lldb::eLaunchFlagDisableASLR);
flags = SetLaunchFlag(flags, arguments.disableSTDIO,
lldb::eLaunchFlagDisableSTDIO);
+#ifdef _WIN32
+ flags = SetLaunchFlag(flags, arguments.console == protocol::eConsoleInternal,
+ lldb::eLaunchFlagUsePipes);
+#endif
launch_info.SetLaunchFlags(flags | lldb::eLaunchFlagDebug |
lldb::eLaunchFlagStopAtEntry);
``````````
</details>
https://github.com/llvm/llvm-project/pull/186472
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