Chris Adams

I've started adding some more advanced ctypes wrappers for the OS X Keychain to PyMacAdmin. There's still a bunch of work to do but the upshot is that you can write code like this and expect it to work:

try:
 keychain = Keychain(options.keychain)
 item = keychain.find_generic_password(
service_name=options.service,
account_name=options.account
 )
print "Removing %s" % item
 keychain.remove(item)
except KeyError, exc:
 print >>sys.stderr, exc.message
except RuntimeError, exc:
 print >>sys.stderr, "Unable to delete keychain item: %s" % exc

and get output like this:

chris@Enceladus:~/Development/pymacadmin [git master] $ ./bin/keychain-delete.py -a "acdha"
Removing GenericPassword(service_name='', account_name='acdha', label='Audioscrobbler: acdha')

There's a bunch of stuff going on behind the scenes now to make things easier than the sadly-unimproved state discussed at length by Wil Shipley back in 2006:

• PyMacAdmin.Security now defines many of the kSec* defines from SecKeychainItem.h, simplifying many calls which either required magic numbers or complicated struct.unpack() calls.
• PyMacAdmin.Security.Keychain now defines a few classes which represent some of the native typedefs: SecKeychainAttribute, SecKeychainAttributeList and SecKeychainAttributeInfo.
• Core PyMacAdmin improvements to make it a little easier to work with Carbon-style APIs:

• mac_strerror() provides a way to lookup the error message for Carbon return codes
• carbon_call() simplifies the process of calling a Carbon function by automatically checking its return code and throwing an exception any time the return code is negative.
• carbon_errcheck() can be used as a ctypes errcheck function using the same logic as carbon_call()
• load_carbon_framework() wraps the ctypes LoadLibrary() method to automatically use carbon_errcheck() for every function in the loaded library - this won't work for functions which use negative return codes for non-error results but the Carbon APIs are pretty consistent in that regard.

If you have any interest in wrapping native Mac APIs with Python please join the discussion over on the PyMacAdmin group - any sort of Python-OS X integration discussion is welcome.