llvm-project/lldb/docs/use/python-reference.rst
rchamala 1ee03d1e09
[lldb] Add ScriptedSymbolLocator plugin for source file resolution (#181334)
## Summary                                                        
                                                                    
Based on discussion from
[RFC](https://discourse.llvm.org/t/rfc-python-callback-for-source-file-resolution/83545),
this PR adds a new `SymbolLocatorScripted` plugin that allows Python
scripts to implement custom symbol and source file resolution logic.
This enables downstream users to build custom symbol servers, source
file remapping, and build artifact resolution entirely in Python.
                                                                    
  ### Changes

- Adds `LocateSourceFile()` to the SymbolLocator plugin interface,
called during source path resolution with a fully loaded `ModuleSP`, so
the plugin has access to the module's UUID, file paths, and symbols.
- Adds `SymbolLocatorScripted` plugin that delegates all four
SymbolLocator methods (`LocateExecutableObjectFile`,
`LocateExecutableSymbolFile`, `DownloadObjectAndSymbolFile`,
`LocateSourceFile`) to a user-provided Python class.
- Adds `ScriptedSymbolLocatorPythonInterface` to bridge C++ calls to
Python, with proper GIL management and error handling.
- Results for `LocateSourceFile` are cached per (module UUID, source
file) pair.
- The Python class is configured via: `settings set
plugin.symbol-locator.scripted.script-class module.ClassName`

  ### Python class interface

  ```python
  class MyLocator:
      def __init__(self, exe_ctx, args): ...
      def locate_source_file(self, module, original_source_file):
  ...
      def locate_executable_object_file(self, module_spec): ...
      def locate_executable_symbol_file(self, module_spec,
  default_search_paths): ...
      def download_object_and_symbol_file(self, module_spec,
  force_lookup, copy_executable): ...
```

  ### Test plan
```
  Added TestScriptedSymbolLocator.py with 3 test cases:
  - test_locate_source_file — verifies the locator resolves source
  files, receives a valid SBModule with UUID, and remaps paths correctly
  - test_locate_source_file_none_fallthrough — verifies returning
None falls through to default LLDB resolution, and that having no script
  class set works normally
  - test_invalid_script_class — verifies graceful handling of
  invalid class names without crashing
```

Co-authored-by: Rahul Reddy Chamala <rachamal@fb.com>
2026-02-14 07:39:00 -08:00

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Python Reference
================
The entire LLDB API is available as Python functions through a script bridging
interface. This means the LLDB API's can be used directly from python either
interactively or to build python apps that provide debugger features.
Additionally, Python can be used as a programmatic interface within the lldb
command interpreter (we refer to this for brevity as the embedded interpreter).
Of course, in this context it has full access to the LLDB API - with some
additional conveniences we will call out in the FAQ.
Python Tutorials
-----------------
The following tutorials and documentation demonstrate various Python capabilities within LLDB:
.. toctree::
:maxdepth: 1
tutorials/accessing-documentation
tutorials/python-embedded-interpreter
tutorials/script-driven-debugging
tutorials/breakpoint-triggered-scripts
tutorials/creating-custom-breakpoints
tutorials/automating-stepping-logic
tutorials/writing-custom-commands
tutorials/implementing-standalone-scripts
tutorials/custom-frame-recognizers
tutorials/extending-target-stop-hooks
tutorials/scripted-symbol-locator