I'll be back in a sex

RubyCocoa and Keychain access [U]

There have been a few posts asking how to access and manipulate the Keychain from within RubyCocoa but no answers supplied. As someone who is just getting into RubyCocoa (and Cocoa all together for that matter), I thought I’d document once and for all the process I took to get it working.

I am running on Leopard and while 10.5 is supposed to ship with BridgeSupport for most frameworks, the Security framework must have been left out. After playing around with using other frameworks (such as the AddressBook framework) and seeing how they were used, I did a bit of digging in the Apple Developer Documentation (incredible resource for anyone starting out) and stumbled across this gem: Generate Framework Metadata.

After reading this, I was accessing the keychain within 5 minutes. Here’s how:

1. Run the following commands (first one will take some time):
   gen_bridge_metadata -f Security -o Security.bridgesupport
mkdir -p /Library/BridgeSupport
mv Security.bridgesupport /Library/BridgeSupport
2. Open an IRB session to test it:
   >> require 'osx/cocoa'
=> true
>> OSX.require_framework 'Security'
=> true
>> defined? OSX::SecKeychainAddGenericPassword()
=> "method"

Hoorah! Two steps! Well, one because the second one was just testing… Now go make password-able RubyCocoa application! I am not sure how to pull this off with deployable apps but I suggest your apps could ship with the file or run those commands on first-run or if the Security.bridgesupport file doesn’t exist. Note: I have not tested either of those scenarios, but I would guess the latter would be more reliable for cross-version development (i.e. Tiger + Leopard)

[ADDITION:] I am just adding an explanation of how to actually use these methods.

1. # Require needed libraries
   
require 'osx/cocoa'
include OSX
require_framework 'Security'


2. # Set up some relevant variables

service = "Test Service"
account = "MyUsername"
password = "MyPassword"


3. # Add password to default keychain (first param)

SecKeychainAddGenericPassword(nil, service.length, service, account.length, account, password.length, password, nil)


4. # Finding a password in default keychain (first param)
   
   status, *password = SecKeychainFindGenericPassword(nil, service.length, service, account.length, account)

# Password-related data
password_length = password.shift # => 10
password_data = password.shift # OSX::ObjcPtr object
password = password_data.bytestr(password_length)

# The last item is another OSX::ObjcPtr. I haven't figured
# out how to cast or use this yet but will post when I've
# figured it out
keychain_item = password.shift

# Yay it works! You can also check the password exists
# in the Keychain Access utility. I've confirmed that
# this works
puts password # => "MyPassword"

[UPDATE 4/8/08]: Below is a fix for the REXML bug some people have been getting (myself included)

There is good news for anyone that has been getting the following error:

undefined local variable or method `trans’ for <UNDEFINED> … </>:REXML::Document

Usage: gen_bridge_metadata [options] <headers…>

Use the `-h’ flag or consult gen_bridge_metadata(1) for help.

There is a very simple fix. This is caused by a typo in the source of REXML. It’s such a massive bug I can’t believe it made it into the release of Ruby but i did some poking around and it looks like they renamed a method and didn’t change all references to it. 

There are two ways to fix it—patching REXML; and patching gen_brige_metadata.

Personally I prefer patching the generator for peace of mind and have submitted the patch at http://bridgesupport.macosforge.org/trac/ticket/1, but I’ll show both fixes.

Patching gen_bridge_metadata

1. Open /usr/bin/gen_bridge_metadata and find the method definition for generate_xml (should be on line 1531)
   
2. Replace 0 in the xml_document.write() with -1 (both occurrences)
3. Save!

Patching REXML

1. Open /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/rexml/document.rb
   
2. Find the line that has ‘if trans’ and change it to ‘if transitive’
3. Save!

Gun on US flight misfires

“A gun carried by a US pilot discharged in mid-air during a packed flight over the Easter holiday. None of the 124 passengers and five crew members on the flight from Denver to Charlotte, North Carolina, was injured and the US Airways Airbus A319 plane landed safely in Charlotte. The pilot, who was not identified, was allowed to carry the gun as part of an anti-terrorist program.” - MX Brisbane,  25 March 2008

In my opinion that is total bullshit. That’s America’s idea of an anti-terrorist tactic on a plane, put a gun ON the plane. I can only think of oh… a hundred ways that could go wrong.