shell-signal

#!/bin/sh -efu
### This file is covered by the GNU General Public License,
### which should be included with libshell as the file LICENSE.
### All copyright information are listed in the COPYING.

if [ -z "${__included_shell_signal-}" ]; then
__included_shell_signal=1

. shell-error
. shell-quote

__shell_signal_handlers=
### Set handler code whan any of the specified signals are received.
### Return code of handler function will be ignored. Special handlers is
### SIG_IGN and SIG_DFL (See signal(2)).
###
### Usage example:
### signal_handler 'echo $arg' TERM EXIT HUP
### signal_handler SIG_IGN     TERM EXIT HUP
### signal_handler SIG_DFL     TERM EXIT HUP
signal_handler()
{
	local action real_action sign
	action="$1"; shift

	for sign; do
		sign="${sign#SIG}"
		case "$action" in
			SIG_IGN)
				eval "unset __signal_handlers_$sign"
				real_action=:
				trap : "$sign"
				;;
			SIG_DFL)
				eval "unset __signal_handlers_$sign"
				real_action=-
				trap - "$sign"
				;;
			*)
				eval "handler=\"\${__signal_handlers_$sign-} \$action;\""
				trap "$handler" "$sign"
				eval "__signal_handlers_$sign=\"\$handler\""
				;;
		esac
	done
}

### Set exit handler. Return code of handler function will be ignored.
###
### Usage example:
### exit_function() { echo "Exit with return code '$1'"; }
### set_cleanup_handler exit_function
__cleanup_handler_name=
set_cleanup_handler()
{
	__cleanup_handler_name="${1-}"
	__cleanup_handler()
	{
		trap - EXIT
		[ -z "${__cleanup_handler_name-}" ] ||
			"$__cleanup_handler_name" "$1" ||:
		exit "$1"
	}
	signal_handler '__cleanup_handler $?' EXIT
	signal_handler '__cleanup_handler  1' HUP PIPE INT QUIT TERM
}

### Remove exit handler.
###
### Usage example: unset_cleanup_handler
unset_cleanup_handler()
{
	signal_handler SIG_DFL EXIT HUP PIPE INT QUIT TERM
	__cleanup_handler_name=
}

fi #__included_shell_signal