CTypes on a 64 bit machine truncates pointers to 32 bits?

[Ron Garret]

CTypes on a 64-bit machine appears to be truncating pointers to 32 bits:

[ron@monster1:~]$ uname -a
Linux monster1 2.6.18-6-amd64 #1 SMP Mon Jun 16 22:30:01 UTC 2008 x86_64
GNU/Linux
[ron@monster1:~]$ cat foo.c
void* foo(void* x) { return x; }
[ron@monster1:~]$ gcc -fPIC -shared foo.c -o foo.so
[ron@monster1:~]$ file foo.so
foo.so: ELF 64-bit LSB shared object, AMD x86-64, version 1 (SYSV), not
stripped
[ron@monster1:~]$ python
Python 2.5 (release25-maint, Jul 23 2008, 18:15:29)
[GCC 4.1.2 20061115 (prerelease) (Debian 4.1.1-21)] on linux2
Type "help", "copyright" , "credits" or "license" for more information.

>>from ctypes import *
>>foolib = cdll.LoadLibrar y('foo.so')
>>foolib.foo(0x F00000000)

0

>>sizeof(c_void _p)

8

>>>

I am aware of http://bugs.python.org/issue1703286 but I get the same
result in Python2.5.2:

[ron@monster1:~]$ py252/bin/python
Python 2.5.2 (r252:60911, Sep 18 2008, 10:48:29)
[GCC 4.1.2 20061115 (prerelease) (Debian 4.1.1-21)] on linux2
Type "help", "copyright" , "credits" or "license" for more information.

>>from ctypes import *
>>foolib = cdll.LoadLibrar y('foo.so')
>>foolib.foo(0x F00000000)

0

>>sizeof(c_void _p)

8

>>>

[=?ISO-8859-1?Q?=22Martin_v=2E_L=F6wis=22?=]

Re: CTypes on a 64 bit machine truncates pointers to 32 bits?

>>>foolib = cdll.LoadLibrar y('foo.so')

>>>foolib.foo(0 xF00000000)

0

Shouldn't you tell ctypes that the argument and the result
of foo is a pointer?

Regards,
Martin

[Ron Garret]

Re: CTypes on a 64 bit machine truncates pointers to 32 bits?

In article <48d34449$0$236 3$9b622d9e@news .freenet.de>,
"Martin v. Löwis" <martin@v.loewi s.dewrote:

>>foolib = cdll.LoadLibrar y('foo.so')
>>foolib.foo(0x F00000000)

0

>
Shouldn't you tell ctypes that the argument and the result
of foo is a pointer?

Yeah... that's it. Default return type is int, which I assumed would be
64 bits on a 64 bit machine, but turns out it's 32. Stupid.

rg

[Lawrence D'Oliveiro]

Re: CTypes on a 64 bit machine truncates pointers to 32 bits?

In message <rNOSPAMon-B959CC.23290518 092008@news.gha .chartermi.net> , Ron
Garret wrote:

Default return type is int, which I assumed would be
64 bits on a 64 bit machine, but turns out it's 32. Stupid.

I think preferred ABIs these days are LP64, not ILP64 or LLP64.