launchd-dev

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April 2010

3 participants
2 discussions

launchd check-in returns error 2 (ENOENT)
by Brent Gulanowski 23 Apr '10

23 Apr '10

This is not urgent but I clearly don't understand something about launchd check-in. We have a couple of daemons that are launched in response to a socket connection. Now, I'm going to straight-up guess that my problem is because I'm not playing by the "rules" -- the daemon's are in inetd mode with Wait as NO. So perhaps launchd just assumes the socket is no good to me and therefore nothing else in the job's plist is of any use. Not sure why it would make such an assumption, but I suppose it's because I can easily read the job property list myself from the file system. Although since you can submit a job directly without a property list file, it would be nice to access it through check-in anyway, say, to read the name of the StandardErrorPath. The daemon runs as a dedicated background user in the root launchd domain. check-in returns NULL and errno was not 2 before calling launch_msg(). As an aside, when I run the daemon from Xcode, errno is 1 (EPERM), which seems weird (what don't I have permission to do?). It would be cool if someone would write a good book on launchd. It's so awesome in so many ways, but it's just not getting the support it deserves. It would also be nice if it had a full-featured Cocoa API. -- #pragma mark signature [[self mailClient] send:[Mail messageWithText:@"From: Brent Gulanowski\nTo: You"];

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launchctl - LAUNCHD_SOCKET
by Eric Long 19 Apr '10

19 Apr '10

Hi, I have a daemon and one of its tasks is to check for launchd jobs in user LaunchAgents folders, see if they failed to execute because the machine was off, or whatever, and start the jobs that were missed. These jobs are all directly related to a feature in our software. The daemon runs in the global root context. When it performs checks it iterates jobs for all logged in users. To start a job, I use NSTask to launch launchctl. If I fail to set the euid to the user whose job I want to start, I get an error saying no such process, or something to that effect. When I set the euid before launching the task, I get back an error saying I must be the root user to conduct the operation and also a socket not connected error message. Looking at the man page for launchctl I see an environment variable named LAUNCHD_SOCKET. My guess is that even though I'm launching the task while the euid is set to the correct user, its still not executing in the user context. I'd attempt to set the LAUNCHD_SOCKET path, but I don't know what the path should point to. Looking at the docs, I see: > Each instance of launchd has a directory in /var/launchd, identified by the > uid or by the uid followed by a pid number, containing a socket for > communicating with it. The environment variable LAUNCHD_SOCKET, when set to > the full path of one of these socket files, specifies a specific instance of > launchd to communicate with. I see directories for users, but the directories are empty. What is the proper way to start the missed job for a given user from my daemon? Thanks, Eric

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