Re: [Pytables-users] New find_library('hdf5dll.dll') call fails in frozen app

[Christoph G. <cg...@uc...>]

On 8/27/2012 9:42 AM, Antonio Valentino wrote:
> Hi Stuart,
>
> Il 27/08/2012 17:43, Stuart Mentzer ha scritto:
>> Hello,
>>
>> I upgraded to PyTables 2.4.0 and I was "freezing" an application on Windows with PyInstaller. The frozen app fails at this new find_library call in __init__.py:
>>
>>        if not ctypes.util.find_library('hdf5dll.dll'):
>>            raise ImportError('Could not load "hdf5dll.dll", please ensure' +
>>                    ' that it can be found in the system path')
>>
>> PyInstaller correctly places this DLL in the same directory as the application .exe where standard Windows DLL search logic will find it. Apparently the find_library doesn't do that in a frozen application. That is a big problem. I had to comment this code out to get a working frozen app.
>>
>> That code was added in revision e9f6919.
>>
>
> It is mainly a sanity check added under request of one of our users:
> https://github.com/PyTables/PyTables/pull/146
>
>
>> This is on Windows 7 64-bit with a 32-bit Python toolchain. Trying both PyInstaller 1.5.1 and 2.0.
>>
>> Should I file a bug report? Any easy work-around?
>>
>> Thanks,
>> Stuart
>>
>
> Yes please file a pull request with your patch.
> It would be nice to preserve the sanity check in standard case so,
> maybe, a good solution could be adding some check on sys.frozen or
> something like that.
>
> Thank you
>

Hello,

As a workaround for frozen distributions, try to add the sys.executable 
directory to os.environ['PATH'] before importing tables.

Ctypes only tries to find a library in the os.environ['PATH'] 
directories, not the current directory or the sys.executable directory 
as one could expect.
http://hg.python.org/cpython/file/64640a02b0ca/Lib/ctypes/util.py#l48

As a workaround, for distributions that place the HDF5 and other DLLs in 
the tables package directory, tables.__init__.py adds the tables package 
directory to os.environ['PATH']. This also makes sure that the DLLs are 
found when loading the hdf5Extension.pyd and other C extension modules 
(another common problem). The use of __file__ to get the tables 
directory should better be wrapped in a try..except statement.
https://github.com/PyTables/PyTables/blob/develop/tables/__init__.py#L24

Christoph