cmpdylib - compare two dynamic shared libraries for compatibility cmpdylib oldLibrary newLibrary cmpdylib compares two versions of a dynamic shared library to see if they are compatible with each other. If the two versions are incompatible, the reason is printed to stdout, and the exit status is nonzero. If they are compatible, nothing is printed, and the exit status is zero.

To see if the two versions are compatible, cmpdylib first verifies that newLibrary was built for all of the architectures that oldLibrary was built for. If so, for each architecture, it checks to see if the global symbols defined in oldLibrary are still defined in newLibrary. It then looks for new symbols, symbols defined in newLibrary that are not defined in oldLibrary. If it finds new symbols, it compares the compatibility version numbers of the two libraries. If the compatibility version number of newLibrary is greater than oldLibrary , the libraries are still compatible. If the compatibility version number is the same or less, the libraries are incompatible.

oldLibrary The older version of the library.

newLibrary The newer version of the library.

This example shows the result of performing cmpdylib on two incompatible versions of the Foundation library. As stated, the versions are incompatible because the newer version was not built for the ppc architecture.

cmpdylib /System/Library/Frameworks/Foundation.framework/Foundation Foundation_proj/Foundation

cmpdylib: file: Foundation_proj/Foundation does not contain architecture: ppc

cmpdylib: new dynamic shared library: Foundation_proj/Foundation does not contain architecture ppc

The exit status is zero if the library versions are compatible and nonzero if they are incompatible. There are lots of other things that could be checked for that are not (such as the Objective C API).