#!/usr/bin/env bash
set -u
set -e

verbose=false
OPTIND=1
while getopts ":v" opt; do
    case "$opt" in
        v) verbose=true ;;
        [?])
			echo "Unknown option -$OPTARG" >&2
            exit 1
        ;;
        :)
			echo "Option -$OPTARG requires an argument" >&2
            exit 1
        ;;
    esac
done
shift $((OPTIND-1))
if [[ "${1:-}" = "--" ]]; then shift; fi

shm_users=()
shm_count=()

while read -r key shmid owner perms bytes nattch stat; do
	[[ "$nattch" = "0" ]] || continue

	if [[ -z "$key" ]] || [[ -z "$shmid" ]] || [[ -z "$owner" ]]; then
		echo "Invalid line from ipcs: \"${key} ${shmid} ${owner} ${nattch}\"!" >&2
		exit 1
	fi
	
	if ! output=$(ipcrm shm "$shmid" 2>&1); then
		echo "Failed to delete line from ipcs: \"${key} ${shmid} ${owner} ${nattch}\"!" >&2
		echo "Output given: \"${output}\"" >&2
		exit 1
	fi
	
	found=false
	i=0
	if [[ -n "${shm_users[*]:-}" ]]; then
		for user in "${shm_users[@]}"; do
			if [[ "$user" = "$owner" ]]; then
				(( ++shm_count[i] ))
				continue 2
			fi
			(( ++i ))
		done
	fi

	shm_users[${#shm_users[*]}]=${owner}
	shm_count[${#shm_count[*]}]=1
done < <(ipcs -m | grep "^0x")

if [[ -z "${shm_users[*]:-}" ]]; then
	! $verbose || echo "No unattached SHM segments found."
	exit 0
fi

total=0
echo "Removed SHM Segments:"
echo "___________________________"
echo "|   OWNER    |   COUNT    |"
echo "|------------|------------|"
for i in $(seq 0 $(( ${#shm_users[*]} - 1 ))); do
	printf '| %-10s | %10d |\n' "${shm_users[i]}" "${shm_count[i]}"
	(( total += shm_count[i] ))
done
echo "|____________|____________|"
echo
echo "Total: $total"