https://github.com/JDevlieghere created
https://github.com/llvm/llvm-project/pull/146132
This PR ensures we correctly restore the cursor column after resizing the
statusline. To ensure we have space for the statusline, we have to emit a
newline to move up everything on screen. The newline causes the cursor to move
to the start of the next line, which needs to be undone.
Normally, we would use escape codes to save & restore the cursor position, but
that doesn't work here, as the cursor position may have (purposely) changed.
Instead, we move the cursor up one line using an escape code, but we weren't
restoring the column.
Interestingly, Editline was able to recover from this issue through the
LineInfo struct which contains the buffer and the cursor location, which allows
us to compute the column. This PR addresses the bug by having Editline
"refresh" the cursor position.
Fixes #134064
>From e601025c14fb609635dc6a9adea5b1ae8b8e4540 Mon Sep 17 00:00:00 2001
From: Jonas Devlieghere <jo...@devlieghere.com>
Date: Fri, 27 Jun 2025 11:08:08 -0700
Subject: [PATCH] [lldb] Correctly restore the cursor column after resizing the
statusline
This PR ensures we correctly restore the cursor column after resizing
the statusline. To ensure we have space for the statusline, we have to
emit a newline to move up everything on screen. The newline causes the
cursor to move to the start of the next line, which needs to be undone.
Normally, we would use escape codes to save & restore the cursor
position, but that doesn't work here, as the cursor position may have
(purposely) changed. Instead, we move the cursor up one line using an
escape code, but we weren't restoring the column.
Interestingly, Editline was able to recover from this issue through the
LineInfo struct which contains the buffer and the cursor location, which
allows us to compute the column. This PR addresses the bug by having
Editline "refresh" the cursor position.
Fixes #134064
---
lldb/include/lldb/Core/Debugger.h | 2 ++
lldb/include/lldb/Core/IOHandler.h | 4 ++++
lldb/include/lldb/Host/Editline.h | 2 ++
lldb/source/Core/Debugger.cpp | 7 +++++++
lldb/source/Core/IOHandler.cpp | 7 +++++++
lldb/source/Core/Statusline.cpp | 19 +++++++++++--------
lldb/source/Host/common/Editline.cpp | 7 +++++++
7 files changed, 40 insertions(+), 8 deletions(-)
diff --git a/lldb/include/lldb/Core/Debugger.h
b/lldb/include/lldb/Core/Debugger.h
index 2087ef2a11562..504f936fe317a 100644
--- a/lldb/include/lldb/Core/Debugger.h
+++ b/lldb/include/lldb/Core/Debugger.h
@@ -227,6 +227,8 @@ class Debugger : public
std::enable_shared_from_this<Debugger>,
const char *GetIOHandlerHelpPrologue();
+ void RefreshIOHandler();
+
void ClearIOHandlers();
bool EnableLog(llvm::StringRef channel,
diff --git a/lldb/include/lldb/Core/IOHandler.h
b/lldb/include/lldb/Core/IOHandler.h
index 2fb3d7a7c9cc3..2672bbe5da2b3 100644
--- a/lldb/include/lldb/Core/IOHandler.h
+++ b/lldb/include/lldb/Core/IOHandler.h
@@ -90,6 +90,8 @@ class IOHandler {
virtual void TerminalSizeChanged() {}
+ virtual void Refresh() {}
+
virtual const char *GetPrompt() {
// Prompt support isn't mandatory
return nullptr;
@@ -404,6 +406,8 @@ class IOHandlerEditline : public IOHandler {
void PrintAsync(const char *s, size_t len, bool is_stdout) override;
+ void Refresh() override;
+
private:
#if LLDB_ENABLE_LIBEDIT
bool IsInputCompleteCallback(Editline *editline, StringList &lines);
diff --git a/lldb/include/lldb/Host/Editline.h
b/lldb/include/lldb/Host/Editline.h
index c202a76758e13..947ad3bfe5ec6 100644
--- a/lldb/include/lldb/Host/Editline.h
+++ b/lldb/include/lldb/Host/Editline.h
@@ -267,6 +267,8 @@ class Editline {
size_t GetTerminalHeight() { return m_terminal_height; }
+ void Refresh();
+
private:
/// Sets the lowest line number for multi-line editing sessions. A value of
/// zero suppresses line number printing in the prompt.
diff --git a/lldb/source/Core/Debugger.cpp b/lldb/source/Core/Debugger.cpp
index 445baf1f63785..ed674ee1275c7 100644
--- a/lldb/source/Core/Debugger.cpp
+++ b/lldb/source/Core/Debugger.cpp
@@ -1445,6 +1445,13 @@ bool Debugger::PopIOHandler(const IOHandlerSP
&pop_reader_sp) {
return true;
}
+void Debugger::RefreshIOHandler() {
+ std::lock_guard<std::recursive_mutex> guard(m_io_handler_stack.GetMutex());
+ IOHandlerSP reader_sp(m_io_handler_stack.Top());
+ if (reader_sp)
+ reader_sp->Refresh();
+}
+
StreamUP Debugger::GetAsyncOutputStream() {
return std::make_unique<StreamAsynchronousIO>(*this,
StreamAsynchronousIO::STDOUT);
diff --git a/lldb/source/Core/IOHandler.cpp b/lldb/source/Core/IOHandler.cpp
index 8aac507eaa0c2..f65a1113f3592 100644
--- a/lldb/source/Core/IOHandler.cpp
+++ b/lldb/source/Core/IOHandler.cpp
@@ -663,3 +663,10 @@ void IOHandlerEditline::PrintAsync(const char *s, size_t
len, bool is_stdout) {
#endif
}
}
+
+void IOHandlerEditline::Refresh() {
+#if LLDB_ENABLE_LIBEDIT
+ if (m_editline_up)
+ m_editline_up->Refresh();
+#endif
+}
diff --git a/lldb/source/Core/Statusline.cpp b/lldb/source/Core/Statusline.cpp
index 8a8640805cac0..8ec57c9fa5bac 100644
--- a/lldb/source/Core/Statusline.cpp
+++ b/lldb/source/Core/Statusline.cpp
@@ -103,20 +103,23 @@ void Statusline::UpdateScrollWindow(ScrollWindowMode
mode) {
(mode == DisableStatusline) ? m_terminal_height : m_terminal_height - 1;
LockedStreamFile locked_stream = stream_sp->Lock();
+
+ if (mode == EnableStatusline) {
+ // Move everything on the screen up.
+ locked_stream << '\n';
+ locked_stream.Printf(ANSI_UP_ROWS, 1);
+ }
+
locked_stream << ANSI_SAVE_CURSOR;
locked_stream.Printf(ANSI_SET_SCROLL_ROWS, scroll_height);
locked_stream << ANSI_RESTORE_CURSOR;
- switch (mode) {
- case EnableStatusline:
- // Move everything on the screen up.
- locked_stream.Printf(ANSI_UP_ROWS, 1);
- locked_stream << '\n';
- break;
- case DisableStatusline:
+
+ if (mode == DisableStatusline) {
// Clear the screen below to hide the old statusline.
locked_stream << ANSI_CLEAR_BELOW;
- break;
}
+
+ m_debugger.RefreshIOHandler();
}
void Statusline::Redraw(bool update) {
diff --git a/lldb/source/Host/common/Editline.cpp
b/lldb/source/Host/common/Editline.cpp
index 431f931d5f3fc..fe4643da21ee0 100644
--- a/lldb/source/Host/common/Editline.cpp
+++ b/lldb/source/Host/common/Editline.cpp
@@ -1709,6 +1709,13 @@ void Editline::PrintAsync(lldb::LockableStreamFileSP
stream_sp, const char *s,
}
}
+void Editline::Refresh() {
+ if (!m_editline || !m_output_stream_sp)
+ return;
+ LockedStreamFile locked_stream = m_output_stream_sp->Lock();
+ MoveCursor(CursorLocation::EditingPrompt, CursorLocation::EditingCursor);
+}
+
bool Editline::CompleteCharacter(char ch, EditLineGetCharType &out) {
#if !LLDB_EDITLINE_USE_WCHAR
if (ch == (char)EOF)
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