cscript/cscript

#!/usr/bin/env sh

# Show help
if [ -z "$1" ] || [ "$1" = "--help" ] || [ "$1" = "-help" ]; then
	echo "Usage:"
	echo "  $(basename "$0") <source.c>... <-option>... [-- <args>...]"
	echo "Or at the beginning of a C file:"
	echo "  #!$(basename "$0") -s [<options>...]"
	echo
	echo "To debug the program in GDB, just set CSCRIPT_GDB=1."
	exit 1
fi

[ -n "$CSCRIPT_GDB" ] && ([ "$CSCRIPT_GDB" = "0" ] || [ "$CSCRIPT_GDB" = "false" ]) && unset CSCRIPT_GDB

# Get file names, options and passed-through args
basedir="."
files=""
opts="-Wall
-pedantic"
shebang_mode=""
at_args=""
args=""
arg() {
	if [ -z "$shebang_mode" ] && [ -n "$at_args" ]; then
		args="$(printf "%s\n%s" "$args" "$1")"
	elif [ "$shebang_mode" = "next_is_file" ]; then
		basedir="$(dirname "$1")"
		files="$(printf "%s\n%s" "$files" "$(basename "$1")")"
		shebang_mode=1
	elif [ -n "$shebang_mode" ]; then
		args="$(printf "%s\n%s" "$args" "$1")"
	else
		case "$1" in
			# Pass through following args
			--)
				at_args=1
				;;
			# Shebang mode (shebang args are not automatically separated;
			# the following arg is always the script filename)
			-s*)
				for a in $(eval "echo $(echo "$1" | cut -c3-)"); do
					arg "$a"
				done
				shebang_mode="next_is_file"
				;;
			# Add option
			-*)
				opts="$(printf "%s\n%s" "$opts" "$1")"
				;;
			# Add source file
			*)
				files="$(printf "%s\n%s" "$files" "$1")"
				;;
		esac
	fi
}
for a in "$@"; do
	arg "$a"
done
[ -n "$CSCRIPT_GDB" ] && opts="$(printf "%s\n%s" "$opts" "-ggdb")"
# Remove empty lines
files="$(printf "%s" "$files" | grep '.')"
opts="$(printf "%s" "$opts" | grep '.')"
args="$(printf "%s" "$args" | grep '.')"

cd "$basedir"

# Check for invalid files
[ -z "$files" ] && echo "No input files" && exit 1
while IFS= read -r l; do
	[ ! -f "$l" ] && [ ! -L "$l" ] &&
		echo "Source file '$l' does not exist" &&
		exit 1
done << EOF
$files
EOF

# Compile and run C program
cleanup() {
	printf "%s" "$files" | xargs -d'\n' sed "s@^//#!@#!@g" -i
	rm -f "$tmpfile"
}
tmpfile="$(mktemp -t "cscript.XXXXXXXXXX")"
printf "%s" "$files" | xargs -d'\n' sed "s@^#!@//#!@g" -i
trap 'cleanup; exit 130' INT
if ! printf "%s\n%s" "$files" "$opts" | xargs -d'\n' cc -o "$tmpfile"; then
	cleanup
	exit 1
fi
if [ -n "$CSCRIPT_GDB" ]; then
	printf "%s" "$args" | xargs -o -d'\n' gdb --args "$tmpfile"
else
	printf "%s" "$args" | xargs -o -d'\n' "$tmpfile"
fi
trap - INT
cleanup