Arguments via environment variables in delink.sh

It was really annoying having to type all that in every time.

ghidra/delink.sh

@@ -3,11 +3,21 @@
 # objects.csv and a Ghidra project via boricj's delinker extension
 
 main() {
-	if [ $# -ne 3 ]; then usage; fi
-
-	ghidra_path=$1
-	project_path=$2
-	project_name=$3
+	if \
+		[ $# -eq 0                        ] &&\
+		[ -n "${GHIDRA_HOME-}"            ] &&\
+		[ -n "${JSRFDECOMP_PROJECTPATH-}" ] &&\
+		[ -n "${JSRFDECOMP_PROJECTNAME-}" ]
+	then
+		ghidra_path=$GHIDRA_HOME
+		project_path=$JSRFDECOMP_PROJECTPATH
+		project_name=$JSRFDECOMP_PROJECTNAME
+	elif [ $# -eq 3 ]; then
+		ghidra_path=$1
+		project_path=$2
+		project_name=$3
+	else usage
+	fi
 
 	printf '=== Delinking object files into ../decompile/target/ ===\n'
 
@@ -39,6 +49,9 @@ usage() {
 		'    GHIDRA_PATH is the path to your Ghidra installation'\
 		'    PROJECT_PATH is the path to your JSRF Ghidra project'\
 		'    PROJECT_NAME is the name of your JSRF Ghidra project'\
+		'Alternatively, the environment variables $GHIDRA_HOME, $JSRFDECOMP_PROJECTPATH,'\
+		'and $JSRFDECOMP_PROJECTNAME can be set, and the script can be called with no'\
+		'arguments.'\
 		''\
 		'Populates the target/ directory with delinked object files using the address'\
 		'ranges given in objects.csv.' >& 2