Re: [be] Need help installing onto my Mac

[Neil Mayhew]

Hi John,

On 2012-02-03 3:12 PM John Brownie wrote:
> I tried installing Bibledit on my Mac with 10.7.3, and ran into a 
> library conflict when trying to start X11. Basically, there seem to be 
> two JPEG libraries, the one installed with MacPorts in /opt/local/lib 
> and the one in the system framework ImageIO. Somehow the library 
> search order is wrong, looking for a routine in ImageIO in 
> /opt/local/lib and failing:
>
> Dyld Error Message:
>   Symbol not found: __cg_jpeg_resync_to_restart
>   Referenced from: 
> /System/Library/Frameworks/ApplicationServices.framework/Versions/A/Frameworks/ImageIO.framework/Versions/A/ImageIO
>   Expected in: /opt/local/lib/libJPEG.dylib
>  in 
> /System/Library/Frameworks/ApplicationServices.framework/Versions/A/Frameworks/ImageIO.framework/Versions/A/ImageIO

I looked around for a bit and my understanding of the problem is as 
follows:

The main library in ImageIO.framework references libJPEG.dylib
libJPEG.dylib exists as a private library of ImageIO.framework
libjpeg.dylib also exists in /opt/local/lib
HFS+ is case-insensitive (by default) so these are considered the same
ImageIO's private build of libjpeg prepends _cg_ to all the library 
function names
The standard libjpeg has the function name without the _cg_
The standard libjpeg is loaded but doesn't have the function ImageIO is 
referencing

> It may be possible to find a work-around by fiddling with library 
> search paths, but I'm not sure how or where to do that.

Unfortunately, if you were to change the search order so that ImageIO's 
libJPEG is loaded instead, anything that needs the functions from the 
standard version won't be able to access them. So this is a no-win 
situation.

> The same problem came up when I was trying to install mono for getting 
> FieldWorks to try to compile, so it's not just Bibledit that has the 
> problem. Hence the cross-post to Collaborate Forum.

It seems to me that Bibledit may not need the MacPorts libjpeg, and it's 
there only because of the work you did with FieldWorks. You could try 
deactivating the jpeg port. which would hide the library, and Bibledit 
might then work.

If this doesn't work, you would have to do something to ensure the two 
libraries have different names. Renaming the ones in ImageIO is 
definitely risky, but maybe you could do something with the MacPorts 
one. For example, /opt/local/lib/libjpeg.dylib is just a symlink to 
libjpeg.8.dylib, and it could be that many things would still work if 
you removed the symlink, since they actually refer to libjpeg.8.dylib.

If Apple is going to use private versions of open-source libraries, they 
should really give them different names, not just rename the functions.

--Neil