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The definition of py_types in python/generator.py does not use the correct PyArg_ParseTuple specifiers. It confuses signed and unsigned integers. The C standard defines an "int" as implementation-specific signedness. You cannot rely on it being one particular way. On Intel, it's generally signed; on ARM, generally unsigned. There exist separate PyArg_ParseTuple specifiers for unsigned integers ("i", "k" and "K" for unsigned int, unsigned long and unsigned long long respectively). When creating bindings for unsigned integer types, python/generator.py should use these specifiers to prevent potential signed/unsigned conversion errors on ARM. It looks like differentiation is already present, but the specifiers are just wrong for the unsigned cases. I don't have a specific failure case; I noticed this when addressing a separate issue and thought I should flag this.
Present in commit 12dc729a711ef586ba632e90ff48667b4176f41f
(In reply to Robie Basak from comment #0) > The definition of py_types in python/generator.py does not use the correct > PyArg_ParseTuple specifiers. It confuses signed and unsigned integers. > > The C standard defines an "int" as implementation-specific signedness. You > cannot rely on it being one particular way. On Intel, it's generally signed; > on ARM, generally unsigned. Wrong. 'char' has implementation-specific signedness, but 'int' is always signed. (See C99 6.2.5 paragraph 4) > > There exist separate PyArg_ParseTuple specifiers for unsigned integers ("i", > "k" and "K" for unsigned int, unsigned long and unsigned long long > respectively). When creating bindings for unsigned integer types, > python/generator.py should use these specifiers to prevent potential > signed/unsigned conversion errors on ARM. It looks like differentiation is > already present, but the specifiers are just wrong for the unsigned cases. Using the correct specifier is still a good idea, for better overflow checking.
> Wrong. 'char' has implementation-specific signedness, but 'int' is always signed. (See C99 6.2.5 paragraph 4) Ah. Thank you for the correction.
I believe this was fixed, there's a series of commits like: commit 1bba3ca4e250c20b63515085f7be4b2c8ec5e237 Author: Pavel Hrdina <phrdina> Date: Tue Feb 23 13:46:45 2016 +0100 libvirt-override: fix PyArg_ParseTuple for size_t