Which PID listens on a given mach port

Question

My application receives mach IPC messages and return answers for the callers. I have mach caller port(msgh_remote_port) and I want to know PID of the caller. Can I find on OSX by the mach port a PID which listen for specific mach port?

Answer 1

The mach port is not directly associated with a process, but instead with a task. The task is then associated with the bsd process structure. To query the ports of a task you can use the mach_port_names function. To get all the open mach ports iterate over all the tasks and use the above mentioned function.

A different approach is to use the procfs filesystem. The procfs filesystem is implemented on top of the fuse filesystem and needs to be manually installed on a system. It is a open source solution. Once the procfs filesystem is installed you can query the ports of a task by accessing the file /proc/proc-id/task/ports. Have a look at Link.