Thomas Heller <[EMAIL PROTECTED]> added the comment:
>> AFAIU, set_errno/get_errno should provide a ctypes-private copy of the real
>> errno.
>> The copy is copied into the 'real' errno just before ffi_call (in
>> Modules/_ctypes/callproc.c),
>> and the real errno is copied in to ctypes copy right after the call.
>
> If you clear errno, anyway, you can also drop the set_errno call, and
My code sample did not intend to clear errno, it was intended to set errno
to the last value that the ctypes-copy had before the call.
> zero-initialize errno before each call. The point of set_errno would
> be that you have the choice of *not* calling it, i.e. passing into
> the function the errno value that was there before you made the API
> call. If you fill something else into errno always, the application has
> no way of not modifying errno before the API call.
To make my point clear (in case is isn't already): In the code
sample that Armin posted, it is impossible to guarantee that no
stdlib function is called between the readdir() and the get_errno() call:
dirent = linux_c_lib.readdir(byref(dir))
if not dirent:
if ctypes.get_errno() == 0:
Consider the garbage collector free some objects that release resources
they have, in other words call functions different from free(3).
Similarly for calling set_errno() or not calling it; other stdlib function
calls in the meantime may have changed errno and that might not be what
the Python programmer expects.
Anyway, how can we proceed? Do you have a suggestion?
Should set_errno() set a flag that is examined and consumed before
call_function_pointer() is called?
__________________________________
Tracker <[EMAIL PROTECTED]>
<http://bugs.python.org/issue1798>
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