#!/bin/sh -
#
#   Oliver Fromme  <olli@fromme.com>
#
#   BSD-style copyright and standard disclaimer applies.
#
#   Save this script as ``errno'' and make a link or symlink
#   to ``signal''.  If called as ``signal'', it will print
#   all signal names and numbers with comments.  If called as
#   ``errno'', it will print all error names and numbers with
#   comments.
#
#   If either a name or a number is specified, that name or
#   number is looked up and displayed.
#
#   Portability:  Tested on FreeBSD and Solaris, probably works on
#                 other platforms, too (depends on the structure
#                 and contents of C header files).
#

case "$0" in
	*sig*)	ACTION=signal
		HEADER=/usr/include/sys/signal.h
		FILTER='1,/typedef/s/#define[ 	]\(SIG[A-Z]\)/\1/p'
		#   Note: There's a space and a tab inside the brackets!
		;;
	*err*)	ACTION=error
		HEADER=/usr/include/sys/errno.h
		FILTER='1,/pseudo-error/s/#define[ 	]\(E[A-Z]\)/\1/p'
		#   Note: There's a space and a tab inside the brackets!
		;;
	*)	echo "${0}:  Don't know what to do." >&2
		exit 1;
		;;
esac

if [ $# -gt 1 ] || expr "x$1" : "x-" >/dev/null; then
	echo "Usage:  `basename $0` [$ACTION name or number]" >&2
	exit 1;
fi

if [ $# -eq 1 ]; then
	if expr "$1" : '[0-9][0-9]*$' >/dev/null; then
		#   Search signal/error number.
		sed -n "$FILTER" < "$HEADER" \
		| awk '
			BEGIN{ found = 0; }
			($2 == '$1'){ found = 1; print; }
			END{ if (!found)
				print "'$ACTION' number '$1' not found";
			}
		'
	elif expr "$1" : '[A-Za-z][A-Za-z]*$' >/dev/null; then
		#   Search signal/error name.
		NAME=`echo $1 | tr '[a-z]' '[A-Z]'`
		sed -n "$FILTER" < "$HEADER" \
		| awk '
			BEGIN{ found = 0; }
			/'$NAME'/{ found = 1; print; }
			END{ if (!found)
				print "'$ACTION' name '$NAME' not found";
			}
		'
	else
		echo "`basename $0`:  syntax error" >&2
		exit 1
	fi
elif [ -t 1 ]; then
	if [ "x$PAGER" = "x" ];then
		PAGER=more
	fi
	sed -n "$FILTER" < "$HEADER" | $PAGER
else
	sed -n "$FILTER" < "$HEADER"
fi