[Lldb-commits] [lldb] Fix a bug in handling ^C at the "y/n/a" completion prompt. (PR #67621)

[via lldb-commits]

https://github.com/jimingham created https://github.com/llvm/llvm-project/pull/67621

We just forget to check for interrupt while waiting for the answer to the prompt. But if we are in the interrupt state then the lower layers of the EditLine code just eat all characters so we never get out of the query prompt. You're pretty much stuck and have to kill lldb.

The solution is to check for the interrupt. The patch is a little bigger because where I needed to check the Interrupt state I only had the ::EditLine object, but the editor state is held in lldb's EditLine wrapper, so I had to do a little work to get my hands on it.

>From fab5e1f67433a29a5d54198d83960d7e608dc480 Mon Sep 17 00:00:00 2001
From: Jim Ingham <jingham at apple.com>
Date: Wed, 27 Sep 2023 17:07:33 -0700
Subject: [PATCH] Fix a bug in handling ^C at the "y/n/a" completion prompt.

We just forget to check for interrupt while waiting for the answer to the prompt. But if we are in the interrupt state then the lower
layers of the EditLine code just eat all characters so we never get out of the query prompt. You're pretty much stuck and have to kill lldb.

The solution is to check for the interrupt. The patch is a little bigger because where I needed to check the Interrupt state I only
had the ::EditLine object, but the editor state is held in lldb's EditLine wrapper, so I had to do a little work to get my hands on it.
---
 lldb/include/lldb/Host/Editline.h             |  4 +++
 lldb/source/Host/common/Editline.cpp          | 28 ++++++++++++-------
 .../completion/TestIOHandlerCompletion.py     |  6 ++++
 3 files changed, 28 insertions(+), 10 deletions(-)

diff --git a/lldb/include/lldb/Host/Editline.h b/lldb/include/lldb/Host/Editline.h
index e1807aa5492680e..c598244150788da 100644
--- a/lldb/include/lldb/Host/Editline.h
+++ b/lldb/include/lldb/Host/Editline.h
@@ -161,6 +161,10 @@ class Editline {
   /// of Editline.
   static Editline *InstanceFor(::EditLine *editline);
 
+  static void
+  DisplayCompletions(Editline &editline,
+                     llvm::ArrayRef<CompletionResult::Completion> results);
+
   /// Sets a string to be used as a prompt, or combined with a line number to
   /// form a prompt.
   void SetPrompt(const char *prompt);
diff --git a/lldb/source/Host/common/Editline.cpp b/lldb/source/Host/common/Editline.cpp
index edefbf4008129e4..82e17ec753ab235 100644
--- a/lldb/source/Host/common/Editline.cpp
+++ b/lldb/source/Host/common/Editline.cpp
@@ -943,12 +943,12 @@ PrintCompletion(FILE *output_file,
   }
 }
 
-static void
-DisplayCompletions(::EditLine *editline, FILE *output_file,
-                   llvm::ArrayRef<CompletionResult::Completion> results) {
+void Editline::DisplayCompletions(
+    Editline &editline, llvm::ArrayRef<CompletionResult::Completion> results) {
   assert(!results.empty());
 
-  fprintf(output_file, "\n" ANSI_CLEAR_BELOW "Available completions:\n");
+  fprintf(editline.m_output_file,
+          "\n" ANSI_CLEAR_BELOW "Available completions:\n");
   const size_t page_size = 40;
   bool all = false;
 
@@ -960,7 +960,7 @@ DisplayCompletions(::EditLine *editline, FILE *output_file,
   const size_t max_len = longest->GetCompletion().size();
 
   if (results.size() < page_size) {
-    PrintCompletion(output_file, results, max_len);
+    PrintCompletion(editline.m_output_file, results, max_len);
     return;
   }
 
@@ -969,17 +969,25 @@ DisplayCompletions(::EditLine *editline, FILE *output_file,
     size_t remaining = results.size() - cur_pos;
     size_t next_size = all ? remaining : std::min(page_size, remaining);
 
-    PrintCompletion(output_file, results.slice(cur_pos, next_size), max_len);
+    PrintCompletion(editline.m_output_file, results.slice(cur_pos, next_size),
+                    max_len);
 
     cur_pos += next_size;
 
     if (cur_pos >= results.size())
       break;
 
-    fprintf(output_file, "More (Y/n/a): ");
+    fprintf(editline.m_output_file, "More (Y/n/a): ");
     char reply = 'n';
-    int got_char = el_getc(editline, &reply);
-    fprintf(output_file, "\n");
+    int got_char = el_getc(editline.m_editline, &reply);
+    // Check for a ^C or other interruption.
+    if (editline.m_editor_status == EditorStatus::Interrupted) {
+      editline.m_editor_status = EditorStatus::Editing;
+      fprintf(editline.m_output_file, "^C\n");
+      break;
+    }
+
+    fprintf(editline.m_output_file, "\n");
     if (got_char == -1 || reply == 'n')
       break;
     if (reply == 'a')
@@ -1050,7 +1058,7 @@ unsigned char Editline::TabCommand(int ch) {
     return CC_REDISPLAY;
   }
 
-  DisplayCompletions(m_editline, m_output_file, results);
+  DisplayCompletions(*this, results);
 
   DisplayInput();
   MoveCursor(CursorLocation::BlockEnd, CursorLocation::EditingCursor);
diff --git a/lldb/test/API/iohandler/completion/TestIOHandlerCompletion.py b/lldb/test/API/iohandler/completion/TestIOHandlerCompletion.py
index 0e28a94adf1e4a3..a74a6572f71f872 100644
--- a/lldb/test/API/iohandler/completion/TestIOHandlerCompletion.py
+++ b/lldb/test/API/iohandler/completion/TestIOHandlerCompletion.py
@@ -75,6 +75,12 @@ def test_completion(self):
         self.child.send("n")
         self.expect_prompt()
 
+        # Start tab completion and abort showing more commands with '^C'.
+        self.child.send("\t")
+        self.child.expect_exact("More (Y/n/a)")
+        self.child.sendcontrol('c')
+        self.expect_prompt()
+
         # Shouldn't crash or anything like that.
         self.child.send("regoinvalid\t")
         self.expect_prompt()