Hi, We are close to the 3.7a3 release and the bug is not fixed yet. I propose to revert the changes on memory allocators right now, and take time to design a proper fix which will respect all constraints.
https://github.com/python/cpython/pull/4532 Today, someone came to me on IRC to complain that calling Py_DecodeLocale() does now crash on Python 3.7. He is doing tests to embed Python on Android. Later he asks me about PyImport_AppendInittab(), but I don't know this function. He told me that it does crash in PyMem_Realloc()... But PyImport_AppendInittab() must be called before Py_Initialize()... It confirms that Python is embedded and that the C API is used before Py_Initialize(). We don't know yet exactly how the the C API is used, which functions are called before Py_Initialize(). Moreover, PEP 432 implementation is still incomplete, and calling _PyRuntime_Initialize() is just not possible, since it's a private API which is not exported... Victor 2017-11-18 1:01 GMT+01:00 Victor Stinner <victor.stin...@gmail.com>: > Hi, > > The CPython internals evolved during Python 3.7 cycle. I would like to > know if we broke the C API or not. > > Nick Coghlan and Eric Snow are working on cleaning up the Python > initialization with the "on going" PEP 432: > https://www.python.org/dev/peps/pep-0432/ > > Many global variables used by the "Python runtime" were move to a new > single "_PyRuntime" variable (big structure made of sub-structures). > See Include/internal/pystate.h. > > A side effect of moving variables from random files into header files > is that it's not more possible to fully initialize _PyRuntime at > "compilation time". For example, previously, it was possible to refer > to local C function (functions declared with "static", so only visible > in the current file). Now a new "initialization function" is required > to must be called. > > In short, it means that using the "Python runtime" before it's > initialized by _PyRuntime_Initialize() is now likely to crash. For > example, calling PyMem_RawMalloc(), before calling > _PyRuntime_Initialize(), now calls the function NULL: dereference a > NULL pointer, and so immediately crash with a segmentation fault. > > I'm writing this email to ask if this change is an issue or not to > embedded Python and the Python C API. Is it still possible to call > "all" functions of the C API before calling Py_Initialize()? > > I was bitten by the bug while reworking the Py_Main() function to > split it into subfunctions and cleanup the code to handle the command > line arguments and environment variables. I fixed the issue in main() > by calling _PyRuntime_Initialize() as soon as possible: it's now the > first instruction of main() :-) (See Programs/python.c) > > To give a more concrete example: Py_DecodeLocale() is the recommanded > function to decode bytes from the operating system, but this function > calls PyMem_RawMalloc() which does crash before > _PyRuntime_Initialize() is called. Is Py_DecodeLocale() used to > initialize Python? > > For example, "void Py_SetProgramName(wchar_t *);" expects a text > string, whereas main() gives argv as bytes. Calling > Py_SetProgramName() from argv requires to decode bytes... So use > Py_DecodeLocale()... > > Should we do something in Py_DecodeLocale()? Maybe crash if > _PyRuntime_Initialize() wasn't called yet? > > Maybe, the minimum change is to expose _PyRuntime_Initialize() in the > public C API? > > Victor _______________________________________________ Python-Dev mailing list Python-Dev@python.org https://mail.python.org/mailman/listinfo/python-dev Unsubscribe: https://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
