pylibfdt: fix get_mem_rsv for newer Python versions

[blmaier]

The test for get_mem_rsv fails on newer versions of Python with the following error.

Traceback (most recent call last): File "/__w/dtc/dtc/tests/pylibfdt_tests.py", line 421, in testReserveMap self.assertEqual([ 0xdeadbeef00000000, 0x100000], AssertionError: Lists differ: [16045690981097406464, 1048576] != [0, 16045690981097406464, 1048576]

First differing element 0: 16045690981097406464 0

Second list contains 1 additional elements. First extra element 2: 1048576

• [16045690981097406464, 1048576]
• [0, 16045690981097406464, 1048576] ? +++

It appears this is because the PyTuple_GET_SIZE() function that was used to build the fdt_get_mem_rsv() return value has changed. It now is returning a non-zero value when it's passed an integer, which causes the SWIG wrapper to append the returned arguments to the return error rather then ignore them.

This is valid behavior per Python's documentation, which says it will "Return the size of the tuple p, which must be non-NULL and point to a tuple; no error checking is performed"[1]. As passing an integer is not a tuple, its return value is undefined.

Fix this issue on older and newer versions by avoiding PyTuple_GET_SIZE() entirely. Always append the arguments to the list, and instead use the wrapper python function to check the first argument and then splice the last two arguments as the return value.

[1] https://docs.python.org/3/c-api/tuple.html#c.PyTuple_GET_SIZE

[blmaier]

Note that the Alpine test failed on the most recent run. This is unrelated to these changes, but is an intermittent failure due to missing Meson dependencies. See this PR for fix https://github.com/dgibson/dtc/pull/129

[dgibson]

Thanks so much for this long overdue fix. Merged.