Open Radar

 
Summary:
CSBackupIsItemExcluded has several issues affecting its accuracy with path exclusions, including relative paths, symbolic links and user-excluded versus programmatically-excluded paths.

Steps to Reproduce:
1. Create a folder named "exclusions" in your home folder, which should not be excluded from Time Machine.

% mkdir exclusions

2. Create a symbolic link from "exclusions-link" to this folder:

% ln -s exclusions exclusions-link

3. Compile the attached source file in the folder:

% clang -framework CoreServices -o excluded excluded.c

4. Create three folders in exclusions-link.  Exclude one from Time Machine by path with Time Machine System Preferences, one by path with tmutil, and one by "stickiness" with tmutil:

% cd exclusions-link
% mkdir ExcludedByPathWithTimeMachineSystemPreferences ExcludedByPathWithTmutil ExcludedByStickiness
% sudo tmutil addexclusion -p ExcludedByPathWithTmutil
Password:
% tmutil addexclusion ExcludedByStickiness           
% open .
[drag "ExcludedByPathWithTimeMachineSystemPreferences" into System Preferences > Time Machine > Options…]

5. Examine these folders for exclusion status with tmutil and with CSBackupIsItemExcluded, with relative, absolute and canonicalized paths:

% tmutil isexcluded Excluded*
% echo Excluded* | xargs -n 1 ./excluded
% echo $PWD/Excluded* | xargs -n 1 ./excluded
% cd ../exclusions
% echo $PWD/Excluded* | xargs -n 1 ./excluded

Expected Results:
All four methods correctly show the paths are excluded.

Actual Results:
tmutil returns as expected; note that it canonicalizes paths as it prints them:

% tmutil isexcluded Excluded*
[Excluded]	/Users/local/exclusions/ExcludedByPathWithTimeMachineSystemPreferences
[Excluded]	/Users/local/exclusions/ExcludedByPathWithTmutil
[Excluded]	/Users/local/exclusions/ExcludedByStickiness

CSBackupIsItemExcluded only returns true for the "sticky" folder, for absolute and relative paths.  Note that the base URL printed below has already been canonicalized:

% echo Excluded* | xargs -n 1 ./excluded
<CFURL 0x7fe2b2c083d0 [0x7fff77512eb0]>{string = ExcludedByPathWithTimeMachineSystemPreferences, encoding = 134217984
	base = <CFURL 0x7fe2b2c08450 [0x7fff77512eb0]>{string = file:///Users/local/exclusions/, encoding = 134217984, base = (null)}}
not excluded
<CFURL 0x7ff0b1d04c20 [0x7fff77512eb0]>{string = ExcludedByPathWithTmutil, encoding = 134217984
	base = <CFURL 0x7ff0b1d04c60 [0x7fff77512eb0]>{string = file:///Users/local/exclusions/, encoding = 134217984, base = (null)}}
not excluded
<CFURL 0x7fcce0e04900 [0x7fff77512eb0]>{string = ExcludedByStickiness, encoding = 134217984
	base = <CFURL 0x7fcce0e04940 [0x7fff77512eb0]>{string = file:///Users/local/exclusions/, encoding = 134217984, base = (null)}}
excluded
% echo $PWD/Excluded* | xargs -n 1 ./excluded
<CFURL 0x7fd368504c50 [0x7fff77512eb0]>{string = file:///Users/local/exclusions-link/ExcludedByPathWithTimeMachineSystemPreferences, encoding = 134217984, base = (null)}
not excluded
<CFURL 0x7fc54b504c40 [0x7fff77512eb0]>{string = file:///Users/local/exclusions-link/ExcludedByPathWithTmutil, encoding = 134217984, base = (null)}
not excluded
<CFURL 0x7fa4f1504bf0 [0x7fff77512eb0]>{string = file:///Users/local/exclusions-link/ExcludedByStickiness, encoding = 134217984, base = (null)}
excluded

With a canonicalized path, CSBackupIsItemExcluded returns true for the programmatically excluded path, but still not the user-excluded one:

% cd ../exclusions
% echo $PWD/Excluded* | xargs -n 1 ./excluded
<CFURL 0x7fa00ac083b0 [0x7fff77512eb0]>{string = file:///Users/local/exclusions/ExcludedByPathWithTimeMachineSystemPreferences, encoding = 134217984, base = (null)}
not excluded
<CFURL 0x7f9513e049d0 [0x7fff77512eb0]>{string = file:///Users/local/exclusions/ExcludedByPathWithTmutil, encoding = 134217984, base = (null)}
excluded by path
<CFURL 0x7f9048c083d0 [0x7fff77512eb0]>{string = file:///Users/local/exclusions/ExcludedByStickiness, encoding = 134217984, base = (null)}
excluded

Version:
Xcode 5.0.2 (5A3005); OS X 10.9.1 (13B42)

Notes:
Canonicalizing the path before calling CSBackupIsItemExcluded would work around the issue with the programmatically-excluded path.  Reading the SkipPaths default from com.apple.TimeMachine directly would allow me to match against the user-excluded path.

% defaults read /Library/Preferences/com.apple.TimeMachine SkipPaths
(
[…]    "~local/exclusions/ExcludedByPathWithTimeMachineSystemPreferences"
)

Configuration:
Mac mini Mid 2011, 2.5 GHz Core i5, 8 GB RAM, RADEON HD 6630M, OS X 10.9.1 (13B42) 
Mac mini Late 2012, 2.6 GHz Core i7, 16 GB RAM, Intel HD4000, OS X 10.8.5 (12F45)

Attachments:
'excluded.c' was successfully uploaded.

[Attached file is uploaded to <http://sabi.net/temp/15909530.c>.]