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errno (and LastError, on Windows). ctypes maintains a module-global, but thread-local, variable that contains an error number; called 'ctypes_errno' for this discussion. This variable is a private copy of the systems 'errno' value; the copy is swapped with the 'errno' variable on several occasions. Foreign functions created with CDLL(..., use_errno=True), when called, swap the values just before the actual function call, and swapped again immediately afterwards. The 'use_errno' parameter defaults to False, in this case 'ctypes_errno' is not touched. The values are also swapped immeditately before and after ctypes callback functions are called, if the callbacks are constructed using the new optional use_errno parameter set to True: CFUNCTYPE(..., use_errno=TRUE) or WINFUNCTYPE(..., use_errno=True). Two new ctypes functions are provided to access the 'ctypes_errno' value from Python: - ctypes.set_errno(value) sets ctypes_errno to 'value', the previous ctypes_errno value is returned. - ctypes.get_errno() returns the current ctypes_errno value. --- On Windows, the same scheme is implemented for the error value which is managed by the GetLastError() and SetLastError() windows api calls. The ctypes functions are 'ctypes.set_last_error(value)' and 'ctypes.get_last_error()', the CDLL and WinDLL optional parameter is named 'use_last_error', defaults to False. --- On Windows, TlsSetValue and TlsGetValue calls are used to provide thread local storage for the variables; ctypes compiled with __GNUC__ uses __thread variables. |
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| .. | ||
| darwin | ||
| libffi | ||
| libffi_arm_wince | ||
| libffi_msvc | ||
| libffi_osx | ||
| _ctypes.c | ||
| _ctypes_test.c | ||
| _ctypes_test.h | ||
| callbacks.c | ||
| callproc.c | ||
| cfield.c | ||
| ctypes.h | ||
| ctypes_dlfcn.h | ||
| malloc_closure.c | ||
| stgdict.c | ||