linux: getting umask of an already running process?

Question

How can I check the umask of a program which is currently running?

[update: another process, not the current process.]

Answer 1

You can attach gdb to a running process and then call umask in the debugger:

(gdb) call umask(0)
[Switching to Thread -1217489200 (LWP 11037)]
$1 = 18
(gdb) call umask(18)
$2 = 0
(gdb) 

(note: 18 = O22)

This suggests that there may be a really ugly way to get the umask using ptrace.