third_party/rust/uniffi_bindgen/src/bindings/python/templates/Helpers.py

   1 # A handful of classes and functions to support the generated data structures.
   2 # This would be a good candidate for isolating in its own ffi-support lib.
   3
   4 class InternalError(Exception):
   5     pass
   6
   7 class _UniffiRustCallStatus(ctypes.Structure):
   8     """
   9     Error runtime.
  10     """
  11     _fields_ = [
  12         ("code", ctypes.c_int8),
  13         ("error_buf", _UniffiRustBuffer),
  14     ]
  15
  16     # These match the values from the uniffi::rustcalls module
  17     CALL_SUCCESS = 0
  18     CALL_ERROR = 1
  19     CALL_PANIC = 2
  20
  21     def __str__(self):
  22         if self.code == _UniffiRustCallStatus.CALL_SUCCESS:
  23             return "_UniffiRustCallStatus(CALL_SUCCESS)"
  24         elif self.code == _UniffiRustCallStatus.CALL_ERROR:
  25             return "_UniffiRustCallStatus(CALL_ERROR)"
  26         elif self.code == _UniffiRustCallStatus.CALL_PANIC:
  27             return "_UniffiRustCallStatus(CALL_PANIC)"
  28         else:
  29             return "_UniffiRustCallStatus(<invalid code>)"
  30
  31 def _rust_call(fn, *args):
  32     # Call a rust function
  33     return _rust_call_with_error(None, fn, *args)
  34
  35 def _rust_call_with_error(error_ffi_converter, fn, *args):
  36     # Call a rust function and handle any errors
  37     #
  38     # This function is used for rust calls that return Result<> and therefore can set the CALL_ERROR status code.
  39     # error_ffi_converter must be set to the _UniffiConverter for the error class that corresponds to the result.
  40     call_status = _UniffiRustCallStatus(code=_UniffiRustCallStatus.CALL_SUCCESS, error_buf=_UniffiRustBuffer(0, 0, None))
  41
  42     args_with_error = args + (ctypes.byref(call_status),)
  43     result = fn(*args_with_error)
  44     _uniffi_check_call_status(error_ffi_converter, call_status)
  45     return result
  46
  47 def _uniffi_check_call_status(error_ffi_converter, call_status):
  48     if call_status.code == _UniffiRustCallStatus.CALL_SUCCESS:
  49         pass
  50     elif call_status.code == _UniffiRustCallStatus.CALL_ERROR:
  51         if error_ffi_converter is None:
  52             call_status.error_buf.free()
  53             raise InternalError("_rust_call_with_error: CALL_ERROR, but error_ffi_converter is None")
  54         else:
  55             raise error_ffi_converter.lift(call_status.error_buf)
  56     elif call_status.code == _UniffiRustCallStatus.CALL_PANIC:
  57         # When the rust code sees a panic, it tries to construct a _UniffiRustBuffer
  58         # with the message.  But if that code panics, then it just sends back
  59         # an empty buffer.
  60         if call_status.error_buf.len > 0:
  61             msg = _UniffiConverterString.lift(call_status.error_buf)
  62         else:
  63             msg = "Unknown rust panic"
  64         raise InternalError(msg)
  65     else:
  66         raise InternalError("Invalid _UniffiRustCallStatus code: {}".format(
  67             call_status.code))
  68
  69 # A function pointer for a callback as defined by UniFFI.
  70 # Rust definition `fn(handle: u64, method: u32, args: _UniffiRustBuffer, buf_ptr: *mut _UniffiRustBuffer) -> int`
  71 _UNIFFI_FOREIGN_CALLBACK_T = ctypes.CFUNCTYPE(ctypes.c_int, ctypes.c_ulonglong, ctypes.c_ulong, ctypes.POINTER(ctypes.c_char), ctypes.c_int, ctypes.POINTER(_UniffiRustBuffer))
  72
  73 # UniFFI future continuation
  74 _UNIFFI_FUTURE_CONTINUATION_T = ctypes.CFUNCTYPE(None, ctypes.c_size_t, ctypes.c_int8)
  75