cast FFI strings

Author: mgeier

sounddevice.py

@@ -572,7 +572,7 @@ def query_devices(device=None, kind=None):
     if not info:
         raise PortAudioError(f'Error querying device {device}')
     assert info.structVersion == 2
-    name_bytes = _ffi.string(info.name)
+    name_bytes = _ffi_string(info.name)
     try:
         # We don't know beforehand if DirectSound and MME device names use
         # 'utf-8' or 'mbcs' encoding.  Let's try 'utf-8' first, because it more
@@ -652,7 +652,7 @@ def query_hostapis(index=None):
         raise PortAudioError(f'Error querying host API {index}')
     assert info.structVersion == 1
     return {
-        'name': _ffi.string(info.name).decode(),
+        'name': _ffi_string(info.name).decode(),
         'devices': [_lib.Pa_HostApiDeviceIndexToDeviceIndex(index, i)
                     for i in range(info.deviceCount)],
         'default_input_device': info.defaultInputDevice,
@@ -722,7 +722,7 @@ def get_portaudio_version():
         (1899, 'PortAudio V19-devel (built Feb 15 2014 23:28:00)')
 
     """
-    return _lib.Pa_GetVersion(), _ffi.string(_lib.Pa_GetVersionText()).decode()
+    return _lib.Pa_GetVersion(), _ffi_string(_lib.Pa_GetVersionText()).decode()
 
 
 class _StreamBase:
@@ -2658,6 +2658,10 @@ def wait(self, ignore_errors=True):
         return self.status if self.status else None
 
 
+def _ffi_string(cdata):
+    return _t.cast(bytes, _ffi.string(cdata))
+
+
 def _remove_self(d):
     """Return a copy of d without the 'self' entry."""
     d = d.copy()
@@ -2788,7 +2792,7 @@ def _check(err, msg=''):
     if err >= 0:
         return err
 
-    errormsg = _ffi.string(_lib.Pa_GetErrorText(err)).decode()
+    errormsg = _ffi_string(_lib.Pa_GetErrorText(err)).decode()
     if msg:
         errormsg = f'{msg}: {errormsg}'
 
@@ -2799,7 +2803,7 @@ def _check(err, msg=''):
         # in scenarios where multiple APIs are being used simultaneously.
         info = _lib.Pa_GetLastHostErrorInfo()
         host_api = _lib.Pa_HostApiTypeIdToHostApiIndex(info.hostApiType)
-        hosterror_text = _ffi.string(info.errorText).decode()
+        hosterror_text = _ffi_string(info.errorText).decode()
         hosterror_info = host_api, info.errorCode, hosterror_text
         raise PortAudioError(errormsg, err, hosterror_info)