ctypes help

[gianluca]

Hy,
I need help about use dll with ctypes. I've compiled my dll C library
and I copied it in c:\windows\system32. When I load it with
"myDLL=cdll.LoadLibrary(find_library("myDLL.dll"))" It seem all OK but
python don't see the dll function. with dir(myDLL) I've only this:
['_FuncPtr', '__class__', '__delattr__', '__dict__', '__doc__',
'__getattr__', '__getattribute__', '__getitem__', '__hash__',
'__init__', '__module__', '__new__', '__reduce__', '__reduce_ex__',
'__repr__', '__setattr__', '__str__', '__weakref__', '_handle',
'_name']

Could anybody help me

Thanks

Gianluca

 

[sturlamolden]

Hy,
I need help about use dll with ctypes. I've compiled my dll C library
and I copied it in c:\windows\system32. When I load it with
"myDLL=cdll.LoadLibrary(find_library("myDLL.dll"))" It seem all OK but
python don't see the dll function. with dir(myDLL) I've only this:
['_FuncPtr', '__class__', '__delattr__', '__dict__', '__doc__',
'__getattr__', '__getattribute__', '__getitem__', '__hash__',
'__init__', '__module__', '__new__', '__reduce__', '__reduce_ex__',
'__repr__', '__setattr__', '__str__', '__weakref__', '_handle',
'_name']

I see nothing wrong here.

 

[gianluca]

Hy,
I need help about use dll with ctypes. I've compiled my dll C library
and I copied it in c:\windows\system32. When I load it with
"myDLL=cdll.LoadLibrary(find_library("myDLL.dll"))" It seem all OK but
python don't see the dll function. with dir(myDLL) I've only this:
['_FuncPtr', '__class__', '__delattr__', '__dict__', '__doc__',
'__getattr__', '__getattribute__', '__getitem__', '__hash__',
'__init__', '__module__', '__new__', '__reduce__', '__reduce_ex__',
'__repr__', '__setattr__', '__str__', '__weakref__', '_handle',
'_name']

Could anybody help me

Gianluca

Since it isn't python, dir can'd do much introspection on the object to produce
the type of output you desire. You have to know the functions (methods) that
you want to call in your dll and call them.

-Larry Bates

Yes, I know it but when I load a function (a=myDLL.myFUNCT()) I've an
exception like this:

Traceback (most recent call last):
File "<pyshell#18>", line 1, in <module>
myDLL.myFUNCT()
File "C:\Python25\lib\ctypes\__init__.py", line 353, in __getattr__
func = self.__getitem__(name)
File "C:\Python25\lib\ctypes\__init__.py", line 358, in __getitem__
func = self._FuncPtr((name_or_ordinal, self))
AttributeError: function 'myFUNCT' not found

Thanks for help

 

[Marc 'BlackJack' Rintsch]

Yes, I know it but when I load a function (a=myDLL.myFUNCT()) I've an
exception like this:

Traceback (most recent call last):
File "<pyshell#18>", line 1, in <module>
myDLL.myFUNCT()
File "C:\Python25\lib\ctypes\__init__.py", line 353, in __getattr__
func = self.__getitem__(name)
File "C:\Python25\lib\ctypes\__init__.py", line 358, in __getitem__
func = self._FuncPtr((name_or_ordinal, self))
AttributeError: function 'myFUNCT' not found

Then maybe the DLL doesn't contain a function called `myFUNCT`. Any
chance you compiled your C as C++ and name mangling kicked in?

Can you show a minimal C source for a DLL, how you compiled it, what you
did on the Python side to call it, and how it fails?

Ciao,
Marc 'BlackJack' Rintsch

 

[gianluca]

Then maybe the DLL doesn't contain a function called `myFUNCT`. Any
chance you compiled your C as C++ and name mangling kicked in?

Can you show a minimal C source for a DLL, how you compiled it, what you
did on the Python side to call it, and how it fails?

Ciao,
Marc 'BlackJack' Rintsch

I've located my dll in c:\windows\system32 (in linux I aven't any
problem) and I compiled it with dev-c++. The source code is C standard
ANSII and is quite havy. If you like I can send it via mail (you can
realy at (e-mail address removed)) . I've tryed to build a wrape with swig
olso with same code and I can access at all the function.
thanks
Gianluca

 

[gianluca]

I've located my dll in c:\windows\system32 (in linux I aven't any
problem) and I compiled it with dev-c++. The source code is C standard
ANSII and is quite havy. If you like I can send it via mail (you can
realy at (e-mail address removed)) . I've tryed to build a wrape with swig
olso with same code and I can access at all the function.

You can use objdump from mingw or cygwin to look inside the dll and
see exactly what it is exporting, eg

objdump -x OurSharedCodeLibrary.dll

This prints a great deal of stuff! In the middle you'll see

[snip]
The Export Tables (interpreted .rdata section contents)
[snip]
Ordinal/Name Pointer] Table
[ 0] OSCL_DEBUG_fakeInitComplete
[ 1] OSCL_close
[ 2] OSCL_displayIdent
[ 3] OSCL_getCurrentDynamicParams
[ 4] OSCL_getCurrentStaticParams
[ 5] OSCL_getErrorString
[ 6] OSCL_getIdent
[snip]

This is a dll we used in a project, and those names exactly worked
with ctypes, eg some snips from the ctypes code

self.dll = cdll.LoadLibrary("OurSharedCodeLibrary")
self.dll.OSCL_getErrorString.restype = c_char_p

def getErrorString(self, status):
return self.dll.OSCL_getErrorString(c_int(status))

Thank you for help!
I've done all you suggest and I've a objdump output like this:
....
[ 86](sec 1)(fl 0x00)(ty 20)(scl 2) (nx 0) 0x00003755 _IsCoverRelD
[ 87](sec 1)(fl 0x00)(ty 20)(scl 2) (nx 0) 0x00003657 _IsCoverRelA
[ 88](sec 1)(fl 0x00)(ty 20)(scl 2) (nx 0) 0x000034f5 _IsCoverDX
[ 89](sec 1)(fl 0x00)(ty 20)(scl 2) (nx 0) 0x0000341b _IsCoverA
[ 90](sec 1)(fl 0x00)(ty 20)(scl 2) (nx 0) 0x00003072 _CoreRelD
[ 91](sec 1)(fl 0x00)(ty 20)(scl 2) (nx 0) 0x00002f5e _CoreRelA
....
my funtions are the __IsCoverRelD, __IsCoverRelA, etc but when I call
it (myLIB.__IsCoverRelA or myLIB.__IsCoverRelA()) I've the same
problem.
Hy
gianluca

 

[Terry Reedy]

| Thank you for help!
| I've done all you suggest and I've a objdump output like this:
| ...
| [ 86](sec 1)(fl 0x00)(ty 20)(scl 2) (nx 0) 0x00003755 _IsCoverRelD
| [ 87](sec 1)(fl 0x00)(ty 20)(scl 2) (nx 0) 0x00003657 _IsCoverRelA
| [ 88](sec 1)(fl 0x00)(ty 20)(scl 2) (nx 0) 0x000034f5 _IsCoverDX
| [ 89](sec 1)(fl 0x00)(ty 20)(scl 2) (nx 0) 0x0000341b _IsCoverA
| [ 90](sec 1)(fl 0x00)(ty 20)(scl 2) (nx 0) 0x00003072 _CoreRelD
| [ 91](sec 1)(fl 0x00)(ty 20)(scl 2) (nx 0) 0x00002f5e _CoreRelA

The name above have one underscore.


| my funtions are the __IsCoverRelD, __IsCoverRelA, etc but when I call
| it (myLIB.__IsCoverRelA or myLIB.__IsCoverRelA()) I've the same
| problem.

These all have two. So if that is what you actually did....

tjr