lldb: Crash in `RunCommandInterpreter` When Using `force_io_methods=True` in Python API (Regression in LLDB 21)

[patryk4815]

Starting with LLDB 21, calling RunCommandInterpreter crashes when
the debugger's output and error streams are initialized using
lldb.SBFile.Create(..., force_io_methods=True) in Python.

The same code works correctly on LLDB 20.

Removing force_io_methods=True (or explicitly setting it to False)
avoids the crash, indicating a regression in LLDB's handling of SBFile
IO redirection.

Probably regression is introduced by:
58279d1

---

Affected Versions

• LLDB 20 -- OK
• LLDB 21 -- CRASH when invoking RunCommandInterpreter

Tested on:

• Fedora 42 (lldb-20) --- works
• Fedora 43 (lldb-21) --- crashes

Install using:

dnf install lldb -y

---

Minimal Reproduction

import lldb
import sys

lldb.SBDebugger.Initialize()
debugger = lldb.SBDebugger.Create()

debugger.SetOutputFile(lldb.SBFile.Create(sys.stdout, borrow=True, force_io_methods=True))
debugger.SetErrorFile(lldb.SBFile.Create(sys.stderr, borrow=True, force_io_methods=True))

# CRASHES on LLDB 21
debugger.RunCommandInterpreter(
    True, False,
    lldb.SBCommandInterpreterRunOptions(),
    0, False, False
)

Notes

• If force_io_methods=True is removed or set to False, no crash occurs.
• The crash happens immediately upon entering RunCommandInterpreter.

---

Expected Behavior

RunCommandInterpreter should run normally, as it does in LLDB 20.

---

Additional context

stdout and stderr is null, crash SIGSEGV

[llvmbot]

@llvm/issue-subscribers-lldb

Author: None (patryk4815)

Starting with **LLDB 21**, calling `RunCommandInterpreter` crashes when the debugger's output and error streams are initialized using `lldb.SBFile.Create(..., force_io_methods=True)` in Python.

The same code works correctly on LLDB 20.

Removing force_io_methods=True (or explicitly setting it to False)
avoids the crash, indicating a regression in LLDB's handling of SBFile
IO redirection.

Probably regression is introduced by:
58279d1

---

Affected Versions

• LLDB 20 -- OK
• LLDB 21 -- CRASH when invoking RunCommandInterpreter

Tested on:

• Fedora 42 (lldb-20) --- works
• Fedora 43 (lldb-21) --- crashes

Install using:

dnf install lldb -y

---

Minimal Reproduction

import lldb
import sys

lldb.SBDebugger.Initialize()
debugger = lldb.SBDebugger.Create()

debugger.SetOutputFile(lldb.SBFile.Create(sys.stdout, borrow=True, force_io_methods=True))
debugger.SetErrorFile(lldb.SBFile.Create(sys.stderr, borrow=True, force_io_methods=True))

# CRASHES on LLDB 21
debugger.RunCommandInterpreter(
    True, False,
    lldb.SBCommandInterpreterRunOptions(),
    0, False, False
)

Notes

• If force_io_methods=True is removed or set to False, no crash occurs.
• The crash happens immediately upon entering RunCommandInterpreter.

---

Expected Behavior

RunCommandInterpreter should run normally, as it does in LLDB 20.

---

Additional context

<img width="940" height="890" alt="Image" src="https://github.com/user-attachments/assets/798b28bb-158d-4cc4-a1a6-0d55434de0a3" />

stdout and stderr is null, crash SIGSEGV