[PATCH] gitk: fix MacOS 10.14 "Mojave" crash on launch

From: Eric Sunshine <sunshine@sunshineco.com>
Date: Jul 24, 2018, 06:51 UTC
Message-ID: <20180724065120.7664-1-sunshine@sunshineco.com>
In-Reply-To: <CAPig+cTJvJLMe4CFOb-yxqwF4udvs4G-BUiT=Kp-NZcfAWAyiQ@mail.gmail.com>

On MacOS, a "wish" application started from the terminal opens in the background, thus doesn't match user expectation that a newly-launched application ought to be placed in the foreground. To address this shortcoming, both gitk and git-gui use Apple Events to send a message to "System Events" instructing it to foreground the "wish" application by PID.

Unfortunately, MacOS 10.14 tightens restrictions on Apple Events, requiring explicit granting of permission to control applications in this fashion, and apparently such granting for "Automation" is not allowed at all[1]. As a consequence gitk crashes outright at launch time with a "Not authorized to send Apple events to System Events" error, thus is entirely unusable on "Mojave".

In contrast, git-gui does not crash since it deliberately[2] catches and ignores Apple Events errors. This does mean that git-gui will not automatically become the foreground application on "Mojave", which is a minor inconvenience but far better than crashing outright as gitk does.

Update gitk to catch and ignore Apple Events errors, mirroring git-gui's behavior, to avoid this crash.

(Finding and implementing an alternate approach to foregrounding the "wish" application on "Mojave" may be desirable but is outside the scope of this crash fix.)

[1]: https://public-inbox.org/git/D295145E-7596-4409-9681-D8ADBB9EBB0C@me.com/ [2]: https://public-inbox.org/git/CABNJ2G+h3zh+=wLA0KHjUn8TsfhqUK1Kn-1_=6hnXVRJUPhuuA@mail.gmail.com/

Reported-by: Evgeny Cherpak <cherpake@me.com>
Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
---

Lack of 'catch' in the 'osascript' invocation in gitk was recognized as a potential problem as far back as June 2013 [3,4]; now it's biting "Mojave" users, making gitk unusable.

[3]: https://public-inbox.org/git/7vk3m7yukc.fsf@alter.siamese.dyndns.org/ [4]: https://public-inbox.org/git/1l424u5.uk987q18u3oxfM%25lists@haller-berlin.de/

 gitk-git/gitk | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/gitk-git/gitk b/gitk-git/gitk
index a14d7a16b2..f13d1807bb 100755
--- a/gitk-git/gitk
+++ b/gitk-git/gitk
@@ -12210,11 +12210,13 @@ if {[catch {package require Tk 8.4} err]} {
 
 # on OSX bring the current Wish process window to front
 if {[tk windowingsystem] eq "aqua"} {
-    exec osascript -e [format {
-        tell application "System Events"
-            set frontmost of processes whose unix id is %d to true
-        end tell
-    } [pid] ]
+    catch {
+	exec osascript -e [format {
+	    tell application "System Events"
+		set frontmost of processes whose unix id is %d to true
+	    end tell
+	} [pid] ]
+    }
 }
 
 # Unset GIT_TRACE var if set

-- 
2.18.0.345.g5c9ce644c3