Conflict between dynamic linking priority in OSX?

Question

There is a dynamic-linking-conflict between different libjpeg dynamic libraries on OSX. First there is a standard native libJPEG.dylib (in /System/Library/Frameworks/ImageIO

Answer 1

You should not set library paths using DYLD_LIBRARY_PATH. As you've discovered, that tends to explode. Executables and libraries should have their library requirements built into them at link time. Use otool -L to find out what the file is looking for:

$ otool -L /System/Library/Frameworks/ImageIO.framework/Versions/A/ImageIO
/System/Library/Frameworks/ImageIO.framework/Versions/A/ImageIO:
    /System/Library/Frameworks/ImageIO.framework/Versions/A/ImageIO (compatibility version 1.0.0, current version 1.0.0)
    ...
    /usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 1197.1.1)

For an example of one of my homebrew-built programs:

$ otool -L /usr/local/bin/gifcolor
/usr/local/bin/gifcolor:
    /usr/local/Cellar/giflib/4.1.6/lib/libgif.4.dylib (compatibility version 6.0.0, current version 6.6.0)
    /usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 159.1.0)

Note that it references /usr/local. If you've built it in such a way that it references the wrong library, I recommend rebuilding and pointing it to the correctly library.

If that's impossible, it is possible to edit what path is used using install_name_tool, but there are cases where this doesn't work, such as if the new path is longer than the old path and you didn't link it with -header_pad_max_install_names. Rebuilding with the correct path is preferred.

Note that there are a few "special" paths available that allow libraries to be found relative to their loader. See @executable_path/ and its kin in the dyld(1) man page.