#!/bin/sh

set -eu

if [ "$#" -lt 2 ]
then
    echo Usage: `basename $0` "<limit> <command>..."
    exit 1
fi

limit="$1"
shift
cgname="limitmem_$$"
echo "limiting memory to $limit (cgroup $cgname) for command $@"

cgm create memory "$cgname" >/dev/null
cgm setvalue memory "$cgname" memory.limit_in_bytes "$limit" >/dev/null
# try also limiting swap usage, but this fails if the system has no swap
cgm setvalue memory "$cgname" memsw.limit_in_bytes "$limit" >/dev/null 2>&1 || true

# spawn subshell to run in the cgroup
set +e
(
set -e
cgm movepid memory "$cgname" `sh -c 'echo $PPID'` > /dev/null
exec "$@"
)
# grab exit code
exitcode=`echo $?`

set -e

echo -n "peak memory used: "
cgm getvalue memory "$cgname" memory.max_usage_in_bytes | tail -1 | cut -f2 -d\"

cgm remove memory "$cgname" >/dev/null
exit $exitcode