[Lldb-commits] [lldb] [lldb/Interpreter] Propagate `script` output back to command return object (PR #109440)

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llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-lldb

Author: Med Ismail Bennani (medismailben)

<details>
<summary>Changes</summary>

When running a oneliner script expression, if the script interpreter returned a value, that value would be printed to the debugger standard output straight from the interpreter instead of being propagated back to the command return object, which would then forward it to its output stream.

This implies that when evaluating a oneliner script expression (with `SBCommandInterpreter::HandleCommand`), the return value would get printed to stdout, but we would not be able to fetch it from the command return object.

This patch solves this issue by extending the default Python `InteractiveConsole` class to keep track of the return value, before include it to the command return object.

rdar://132420488

---
Full diff: https://github.com/llvm/llvm-project/pull/109440.diff


2 Files Affected:

- (modified) lldb/source/Interpreter/embedded_interpreter.py (+36-3) 
- (modified) lldb/source/Plugins/ScriptInterpreter/Python/ScriptInterpreterPython.cpp (+5-2) 


``````````diff
diff --git a/lldb/source/Interpreter/embedded_interpreter.py b/lldb/source/Interpreter/embedded_interpreter.py
index a487592ef1aee5..fd5c44d0121fbd 100644
--- a/lldb/source/Interpreter/embedded_interpreter.py
+++ b/lldb/source/Interpreter/embedded_interpreter.py
@@ -8,6 +8,8 @@
 import lldb
 import traceback
 
+from io import StringIO
+
 try:
     import readline
     import rlcompleter
@@ -116,19 +118,50 @@ def run_python_interpreter(local_dict):
             print("Script exited with code %s" % e.code)
 
 
+class LLDBInteractiveConsole(code.InteractiveConsole):
+    def __init__(self, locals=None):
+        super().__init__(locals)
+        self.result_output = None
+
+    ### Implementation detail:
+    ### https://docs.python.org/3/library/code.html#code.InteractiveInterpreter.runsource
+    def runsource(self, source, filename="<input>", symbol="single"):
+        # Redirect stdout to capture print statements
+        old_stdout = sys.stdout
+        sys.stdout = result_output = StringIO()
+
+        try:
+            compiled_code = self.compile(source, filename, symbol)
+            if compiled_code is None:
+                return False
+
+            exec(compiled_code, self.locals)
+            return True
+        except Exception as e:
+            self.showsyntaxerror(filename)
+            return False
+        finally:
+            self.result_output = result_output
+            sys.stdout = old_stdout
+
+    def get_last_result(self):
+        return self.result_output.getvalue()
+
 def run_one_line(local_dict, input_string):
     global g_run_one_line_str
     try:
         input_string = strip_and_check_exit(input_string)
-        repl = code.InteractiveConsole(local_dict)
+        repl = LLDBInteractiveConsole(local_dict)
         if input_string:
             # A newline is appended to support one-line statements containing
             # control flow. For example "if True: print(1)" silently does
             # nothing, but works with a newline: "if True: print(1)\n".
             input_string += "\n"
-            repl.runsource(input_string)
+            if repl.runsource(input_string):
+                return repl.get_last_result()
         elif g_run_one_line_str:
-            repl.runsource(g_run_one_line_str)
+            if repl.runsource(g_run_one_line_str):
+                return repl.get_last_result()
     except LLDBExit:
         pass
     except SystemExit as e:
diff --git a/lldb/source/Plugins/ScriptInterpreter/Python/ScriptInterpreterPython.cpp b/lldb/source/Plugins/ScriptInterpreter/Python/ScriptInterpreterPython.cpp
index 63691d24f0dadb..30b67ce48a4be9 100644
--- a/lldb/source/Plugins/ScriptInterpreter/Python/ScriptInterpreterPython.cpp
+++ b/lldb/source/Plugins/ScriptInterpreter/Python/ScriptInterpreterPython.cpp
@@ -884,9 +884,12 @@ bool ScriptInterpreterPythonImpl::ExecuteOneLine(
                   PyRefType::Owned,
                   PyObject_CallObject(m_run_one_line_function.get(),
                                       pargs.get()));
-              if (return_value.IsValid())
+              if (return_value.IsValid()) {
                 success = true;
-              else if (options.GetMaskoutErrors() && PyErr_Occurred()) {
+                PythonString repr = return_value.Repr();
+                if (repr && repr.GetSize())
+                  result->AppendMessage(repr.GetString());
+              } else if (options.GetMaskoutErrors() && PyErr_Occurred()) {
                 PyErr_Print();
                 PyErr_Clear();
               }

``````````

</details>


https://github.com/llvm/llvm-project/pull/109440