[lldb/Driver] Support terminal resizing

lldb/include/lldb/Core/IOHandler.h

@@ -95,6 +95,8 @@ class IOHandler {
 
   virtual void Deactivate() { m_active = false; }
 
+  virtual void TerminalSizeChanged() {}
+
   virtual const char *GetPrompt() {
     // Prompt support isn't mandatory
     return nullptr;
@@ -369,6 +371,8 @@ class IOHandlerEditline : public IOHandler {
 
   void Deactivate() override;
 
+  void TerminalSizeChanged() override;
+
   ConstString GetControlSequence(char ch) override {
     return m_delegate.IOHandlerGetControlSequence(ch);
   }

lldb/include/lldb/Host/Editline.h

@@ -19,13 +19,10 @@
 //    good amount of the text will
 //    disappear.  It's still in the buffer, just invisible.
 // b) The prompt printing logic for dealing with ANSI formatting characters is
-// broken, which is why we're
-//    working around it here.
-// c) When resizing the terminal window, if the cursor moves between rows
-// libedit will get confused. d) The incremental search uses escape to cancel
-// input, so it's confused by
+// broken, which is why we're working around it here.
+// c) The incremental search uses escape to cancel input, so it's confused by
 // ANSI sequences starting with escape.
-// e) Emoji support is fairly terrible, presumably it doesn't understand
+// d) Emoji support is fairly terrible, presumably it doesn't understand
 // composed characters?
 
 #ifndef liblldb_Editline_h_
@@ -50,6 +47,7 @@
 #include <histedit.h>
 #endif
 
+#include <csignal>
 #include <mutex>
 #include <string>
 #include <vector>
@@ -171,9 +169,7 @@ class Editline {
   /// editing scenarios.
   void SetContinuationPrompt(const char *continuation_prompt);
 
-  /// Required to update the width of the terminal registered for I/O.  It is
-  /// critical that this
-  /// be correct at all times.
+  /// Call when the terminal size changes
   void TerminalSizeChanged();
 
   /// Returns the prompt established by SetPrompt()
@@ -328,6 +324,8 @@ class Editline {
 
   bool CompleteCharacter(char ch, EditLineGetCharType &out);
 
+  void ApplyTerminalSizeChange();
+
 private:
 #if LLDB_EDITLINE_USE_WCHAR
   std::wstring_convert<std::codecvt_utf8<wchar_t>> m_utf8conv;
@@ -350,6 +348,7 @@ class Editline {
   std::string m_set_continuation_prompt;
   std::string m_current_prompt;
   bool m_needs_prompt_repaint = false;
+  volatile std::sig_atomic_t m_terminal_size_has_changed = 0;
   std::string m_editor_name;
   FILE *m_input_file;
   FILE *m_output_file;

lldb/source/Core/Debugger.cpp

@@ -388,6 +388,9 @@ uint32_t Debugger::GetTerminalWidth() const {
 }
 
 bool Debugger::SetTerminalWidth(uint32_t term_width) {
+  if (auto handler_sp = m_io_handler_stack.Top())
+    handler_sp->TerminalSizeChanged();
+
   const uint32_t idx = ePropertyTerminalWidth;
   return m_collection_sp->SetPropertyAtIndexAsSInt64(nullptr, idx, term_width);
 }

lldb/source/Core/IOHandler.cpp

@@ -287,6 +287,12 @@ void IOHandlerEditline::Deactivate() {
   m_delegate.IOHandlerDeactivated(*this);
 }
 
+void IOHandlerEditline::TerminalSizeChanged() {
+#if LLDB_ENABLE_LIBEDIT
+  m_editline_up->TerminalSizeChanged();
+#endif
+}
+
 // Split out a line from the buffer, if there is a full one to get.
 static Optional<std::string> SplitLine(std::string &line_buffer) {
   size_t pos = line_buffer.find('\n');

lldb/source/Host/common/Editline.cpp

@@ -563,6 +563,9 @@ int Editline::GetCharacter(EditLineGetCharType *c) {
     lldb::ConnectionStatus status = lldb::eConnectionStatusSuccess;
     char ch = 0;
 
+    if (m_terminal_size_has_changed)
+      ApplyTerminalSizeChange();
+
     // This mutex is locked by our caller (GetLine). Unlock it while we read a
     // character (blocking operation), so we do not hold the mutex
     // indefinitely. This gives a chance for someone to interrupt us. After
@@ -1055,7 +1058,7 @@ void Editline::ConfigureEditor(bool multiline) {
 
   m_editline =
       el_init(m_editor_name.c_str(), m_input_file, m_output_file, m_error_file);
-  TerminalSizeChanged();
+  ApplyTerminalSizeChange();
 
   if (m_history_sp && m_history_sp->IsValid()) {
     if (!m_history_sp->Load()) {
@@ -1308,28 +1311,32 @@ void Editline::SetContinuationPrompt(const char *continuation_prompt) {
       continuation_prompt == nullptr ? "" : continuation_prompt;
 }
 
-void Editline::TerminalSizeChanged() {
-  if (m_editline != nullptr) {
-    el_resize(m_editline);
-    int columns;
-    // This function is documenting as taking (const char *, void *) for the
-    // vararg part, but in reality in was consuming arguments until the first
-    // null pointer. This was fixed in libedit in April 2019
-    // <http://mail-index.netbsd.org/source-changes/2019/04/26/msg105454.html>,
-    // but we're keeping the workaround until a version with that fix is more
-    // widely available.
-    if (el_get(m_editline, EL_GETTC, "co", &columns, nullptr) == 0) {
-      m_terminal_width = columns;
-      if (m_current_line_rows != -1) {
-        const LineInfoW *info = el_wline(m_editline);
-        int lineLength =
-            (int)((info->lastchar - info->buffer) + GetPromptWidth());
-        m_current_line_rows = (lineLength / columns) + 1;
-      }
-    } else {
-      m_terminal_width = INT_MAX;
-      m_current_line_rows = 1;
+void Editline::TerminalSizeChanged() { m_terminal_size_has_changed = 1; }
+
+void Editline::ApplyTerminalSizeChange() {
+  if (!m_editline)
+    return;
+
+  m_terminal_size_has_changed = 0;
+  el_resize(m_editline);
+  int columns;
+  // This function is documenting as taking (const char *, void *) for the
+  // vararg part, but in reality in was consuming arguments until the first
+  // null pointer. This was fixed in libedit in April 2019
+  // <http://mail-index.netbsd.org/source-changes/2019/04/26/msg105454.html>,
+  // but we're keeping the workaround until a version with that fix is more
+  // widely available.
+  if (el_get(m_editline, EL_GETTC, "co", &columns, nullptr) == 0) {
+    m_terminal_width = columns;
+    if (m_current_line_rows != -1) {
+      const LineInfoW *info = el_wline(m_editline);
+      int lineLength =
+          (int)((info->lastchar - info->buffer) + GetPromptWidth());
+      m_current_line_rows = (lineLength / columns) + 1;
     }
+  } else {
+    m_terminal_width = INT_MAX;
+    m_current_line_rows = 1;
   }
 }
 

lldb/test/API/iohandler/resize/TestIOHandlerResize.py

@@ -0,0 +1,36 @@
+"""
+Test resizing in our IOHandlers.
+"""
+
+import os
+
+import lldb
+from lldbsuite.test.decorators import *
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test.lldbpexpect import PExpectTest
+
+class IOHandlerCompletionTest(PExpectTest):
+
+    mydir = TestBase.compute_mydir(__file__)
+
+    # PExpect uses many timeouts internally and doesn't play well
+    # under ASAN on a loaded machine..
+    @skipIfAsan
+    @skipIfEditlineSupportMissing
+    def test_resize(self):
+
+        # Start with a small window
+        self.launch(dimensions=(10,10))
+
+        self.child.send("his is a long sentence missing its first letter.")
+
+        # Now resize to something bigger
+        self.child.setwinsize(100,500)
+
+        # Hit "left" 60 times (to go to the beginning of the line) and insert
+        # a character.
+        self.child.send(60 * "\033[D")
+        self.child.send("T")
+
+        self.child.expect_exact("(lldb) This is a long sentence missing its first letter.")
+        self.quit()