Mac OS X: Getting detailed process information (specifically its launch arguments) for arbitrary running applications using its PID.

Question

I am trying to detect when particular applications are launched.

Currently I am using NSWorkspace, registering for the "did launch application" notification. I also use the runningApplications method to get apps that are currently running when my app starts.

For most apps, the name of the app bundle is enough. I have a plist of "known apps" that I cross check with the name of that passed in the notification.

This works fine until you come across an app that acts as a proxy for launching another application using command line arguments.

Example: The newly released Portal on the Mac doesn't have a dedicated app bundle. Steam can create a shortcut, which serves as nothing more than to launch the hl2_osx app with the -game argument and portal as it's parameter.

Since more Source based games are heading to the Mac, I imagine they'll use the same method to launch, effectively running the hl2_osx app with the -game argument.

Is there a nice way to get a list of the arguments (and their parameters) using a Cocoa API?

NSProcessInfo comes close, offering an `-arguments' method, but only provides information for its own process...

NSRunningApplication offers the ability to get information about arbitrary apps using a PID, but no command line args...

Is there anything that fills the gap between the two?

I'm trying not to go down the route of spawning an NSTask to run ps -p [pid] and parsing the output... I'd prefer something more high level.

Answer 1

Nope - running ps is your best bet. Standard process info interfaces aren't supported on OS X (noop versions were provided in OS X 10.4, but removed thereafter) and the private interfaces are likely to change between OS X revisions.

If you're willing to lock yourself into a single OS X version, all the source is available, for example for ps or libproc; you'll also need to run as root.

Answer 2

You could use whatever ps uses, though it isn't cocoa based. According to Singh, ps is based on kvm and sysctl calls. Pouring over the source, the pertinant calls seem to be kvm_openfiles, kvm_getprocs and kvm_getargv. To get the command line arguments, first call kvm_openfiles to get access to the kernel memory space, then use kvm_getprocs to get kernel process info, then kvm_getargv.

The use of sysctl in ps seems less relevant to your goal; it's used to get other information, such as the group ID and parent proces ID. The particular sysctl name used is {CTL_KERN, KERN_PROC, KERN_PROC_which, flags}, where which specifies a process filter (e.g. ALL, PID) and flags are arguments for the filter (the details are in the sysctl man page).

OS X doesn't have support procfs, but Singh developed a FUSE based version, released under GPLv2. If you bundle it with your application, you'll have to release it under GPLv2 as well. Most of MacFUSE is released under a BSD-style license, so it can be distributed with your app without making it open source (fusefs/fuse_nodehash.c is released under Apple's open source license, but it also allows linking to closed source apps).

The question "Get other process' argv in OS X using C" should be of use, as it has sample code using kvm and sysctl. TN 2050 "Observing Process Lifetimes Without Polling" may also be of use to you.