Enhanced process coredump routines.
This brings in the following features:
1) Limit number of cores per process via the %I coredump formatter.
Example:
if corefilename is set to %N.%I.core AND num_cores = 3, then
if a process "rpd" cores, then the corefile will be named
"rpd.0.core", however if it cores again, then the kernel will
generate "rpd.1.core" until we hit the limit of "num_cores".
this is useful to get several corefiles, but also prevent filling
the machine with corefiles.
2) Encode machine hostname in core dump name via %H.
3) Compress coredumps, useful for embedded platforms with limited space.
A sysctl kern.compress_user_cores is made available if turned on.
To enable compressed coredumps, the following config options need to be set:
options COMPRESS_USER_CORES
device zlib # brings in the zlib requirements.
device gzio # brings in the kernel vnode gzip output module.
4) Eventhandlers are fired to indicate coredumps in progress.
5) The imgact sv_coredump routine has grown a flag to pass in more
state, currently this is used only for passing a flag down to compress
the coredump or not.
Note that the gzio facility can be used for generic output of gzip'd
streams via vnodes.
Obtained from: Juniper Networks
Reviewed by: kan
e722820434