July 2011 - launchd-dev - lists.macosforge.org

Install and load a launch daemon without a reboot
by Jeremy Reichman 20 Oct '11

20 Oct '11

What is considered the current best practice for installing and then running a launch daemon, while avoiding a reboot? I didn't see exactly what I was looking for in my list archive or found it in any documentation on installation packages. I have reviewed TN2083, specifically the "Starting a Daemon" section. That answers most of my question but it would be helpful to have confirmation. Besides the conditions listed in TN2083, I'd like my installer to behave well when installed to a disk other than the current startup volume. I need to target Mac OS X 10.5 and 10.6. It looks as if I'd need to test for the right conditions and then run launchctl to load the property list. Roughly -- not production code -- it looks like I'd need a postinstall and postupgrade script to do the following: # Test if the destination volume for the payload and the root volume path are the same if [ "$3" = "$4" ] ; then # Quick test to see if the script is run by root if [ `/usr/bin/whoami` = "root" ] ; then /bin/launchctl load "$3/Library/LaunchDaemons/com.vendor.launchdaemon.plist" fi fi exit 0 Is that the right approach? Thanks! -- Jeremy

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Bug in Lion: WatchPath agents succeed, but respawned for a second launch
by Jerry Krinock 28 Jul '11

28 Jul '11

In Lion, launchd tasks with a WatchPath trigger are triggered as expected, but are then respawned to run after a second time after their ThrottleInterval. This does not happen in Snow Leopard. One would think that this bug might have something to do with document Auto Save if the WatchPath was opened in an app that had Auto Save enabled, but that is not necessary; as shown in the steps below, it occurs if I simply 'touch' the WatchPath. Same thing happens if I modify the WatchPath file in BBEdit 9.0, which does not have Auto Save enabled. Also, this bug does not require opening a text file; I discovered it by testing my app which launches a background tool which works for about 10 seconds and then quits. When running under OS X Lion, it always gets launched twice. Please look at my steps below and tell me if my expectations are incorrect. Does anyone think that this is not a serious bug in Lion? Thanks, Jerry Krinock STEPS TO REPRODUCE: 1. Create a target text file named "Junk.txt", with any text, in your Home folder. 2. Create a trigger text file named "TriggerFile.txt", with any text, on your Desktop. 3. Create a launch agent file named "jerry.launchd.test.plist" in ~/Library/LaunchAgents containing the following text: <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd"> <plist version="1.0"> <dict> <key>Label</key> <string>jerry.launchd.test</string> <key>ProgramArguments</key> <array> <string>/usr/bin/open</string> <string>/Users/jk/Junk.txt</string> </array> <key>ThrottleInterval</key> <integer>61</integer> <key>WatchPaths</key> <array> <string>/Users/jk/Desktop/TriggerFile.txt</string> </array> </dict> </plist> where, of course, you have replaced /jk/ with /yourShortName/. 4. Load the agent file by running this command launchctl load ~/Library/LaunchAgents/jerry.launchd.test.plist. 5. In Console.app, open a window to System Log Queries ▸ All Messages. 6. Trigger the agent by running this command: touch ~/Desktop/TriggerFile.txt Expected and Actual Result: The file Junk.txt opens in your text editor. Additional Unexpected Results: Message is logged into Console: com.apple.launchd.peruser.501: (jerry.launchd.test) Throttling respawn: Will start in 61 seconds Note that 61 seconds is the ThrottleInterval. 7. Close the window to Junk.txt which has opened. Additional Bad (but not unexpected) Result: The window to Junk.txt opens *again* 61 seconds after the first opening. Regression: Repeat the test in Snow Leopard; the target file is only opened once, as expected.

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Setting up an AF_UNIX based launchd server
by mailist＠ericgorr.net 25 Jul '11

25 Jul '11

I have been able to setup a AF_INET launchd based server, but, as I understand it, an AF_UNIX based server offers better performance and there is no need to even think about allowing anything outside of the local machine to access the server. I have made an attempt to get something working, but it is not working yet. I am sure there are several problems with the test code, which can be found at: http://ericgorr.net/pq/AF_UNIX.zip (Developed on Mac OS X 10.6.8 using Xcode 4) On the client side, I try to connect to the server with the following code: #define kServerSocketPath "/var/tmp/net.ericgorr.testserver/Socket" int client_connect( void ) { int socketFD = socket( AF_UNIX, SOCK_STREAM, 0 ); assert( socketFD != -1 ); struct sockaddr_un addr; addr.sun_len = sizeof( addr ); addr.sun_family = AF_UNIX; strcpy( addr.sun_path, kServerSocketPath ); int result; int err; result = connect( socketFD, (struct sockaddr *)&socketFD, sizeof( socketFD ) ); err = MoreUNIXErrno( result ); CFShow( CFStringCreateWithFormat( NULL, NULL, CFSTR( "client_connect: %d" ), err ) ); assert( err == 0 ); return socketFD; } However, the connect call sets errno to 2, which I believes means that it cannot find kServerSocketPath. On the server side, I have the following plist: <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd"> <plist version="1.0"> <dict> <key>EnableTransactions</key> <true/> <key>Label</key> <string>net.ericgorr.testserver</string> <key>Program</key> <string>/usr/local/libexec/testserver</string> <key>ProgramArguments</key> <array> <string>testserver</string> <string>launchd</string> </array> <key>Sockets</key> <dict> <key>net.ericgorr.testserver.sock</key> <dict> <key>SockFamily</key> <string>Unix</string> <key>SockPathName</key> <string>/var/tmp/net.ericgorr.testserver/Socket</string> <key>SockPathMode</key> <integer>438</integer> <key>SockType</key> <string>Stream</string> </dict> </dict> </dict> </plist> One question is how should /var/tmp/net.ericgorr.testserver/Socket be created? Another question is, after I can launch the server, the server will need to check in with launchd and I need to know what index should be passed to launch_data_array_get_index...? And, where is this documented? These questions seem like they should be straightforward... Thank you.

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How to run a few instances of a daemon (agent)?
by Nick 12 Jul '11

12 Jul '11

Hello By default, launchd starts a daemon or an agent, by doing the following 1) either "launchctl load /path/to/daemon.plist" is executed, or the plist is loaded automatically when the system starts 2) "launchctl start" is executed (if <string>RunAnLoad</string> is set to <boolean>false</boolean> then, only one instance is being run. I am wondering, if I could run several instances of the same daemon or agent (using launchd). Would it be possible, or I need to daemonize the process by myself, using an old unix way? Thanks, Nick

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