FIX: Handle special shell characters when filtering TERM.

The double quotes used in the filter_command erroneously expand $VARIABLE, and due to missing quoting in the eval() of filter_command, multiple spaces are condensed into a single space.
Introduce a new function shellquote() to correctly quote each filter TERM.

tests/t1300-ls.sh

@@ -94,6 +94,40 @@ TODO: 1 of 3 tasks shown
 TODO: 1 of 3 tasks shown
 EOF
 
+#
+# check the filtering of TERM containing characters that are special to the
+# shell, like variables, quotes, and multiple subsequent spaces.
+#
+cat > todo.txt <<'EOF'
+earn some pennies
+earn some $$
+earn some "money"
+get money from O'Brian
+just get   money!
+EOF
+test_todo_session 'checking filtering of special characters' <<'EOF'
+>>> todo.sh ls '$$'
+2 earn some $$
+--
+TODO: 1 of 5 tasks shown
+
+>>> todo.sh ls '"money"'
+3 earn some "money"
+--
+TODO: 1 of 5 tasks shown
+
+>>> todo.sh ls "O'Brian"
+4 get money from O'Brian
+--
+TODO: 1 of 5 tasks shown
+
+>>> todo.sh ls "get   money"
+5 just get   money!
+--
+TODO: 1 of 5 tasks shown
+EOF
+
+
 #
 # check the x command line option
 #

todo.sh

@@ -663,6 +663,11 @@ _addto() {
     fi
 }
 
+shellquote()
+{
+    typeset -r qq=\'; printf %s\\n "'${1//\'/${qq}\\${qq}${qq}}'";
+}
+
 filtercommand()
 {
     filter=${1:-}
@@ -677,13 +682,13 @@ filtercommand()
         then
             ## First character isn't a dash: hide lines that don't match
             ## this $search_term
-            filter="${filter:-}${filter:+ | }grep -i \"$search_term\""
+            filter="${filter:-}${filter:+ | }grep -i $(shellquote "$search_term")"
         else
             ## First character is a dash: hide lines that match this
             ## $search_term
             #
             ## Remove the first character (-) before adding to our filter command
-            filter="${filter:-}${filter:+ | }grep -v -i \"${search_term:1}\""
+            filter="${filter:-}${filter:+ | }grep -v -i '$(shellquote "${search_term:1}")'"
         fi
     done
 
@@ -736,7 +741,7 @@ _list() {
         | grep -v "^[ 0-9]\+ *$"
     )
     if [ "${filter_command}" ]; then
-        filtered_items=$(echo -n "$items" | eval ${filter_command})
+        filtered_items=$(echo -n "$items" | eval "${filter_command}")
     else
         filtered_items=$items
     fi
@@ -790,7 +795,7 @@ _list() {
     fi
 }
 
-export -f cleaninput filtercommand _list die
+export -f cleaninput shellquote filtercommand _list die
 
 # == HANDLE ACTION ==
 action=$( printf "%s\n" "$ACTION" | tr 'A-Z' 'a-z' )
@@ -1056,7 +1061,7 @@ case $action in
 
 "listproj" | "lsprj" )
     shift
-    eval $(filtercommand 'cat "$TODO_FILE"' '' "$@") | grep -o '[^ ]*+[^ ]\+' | grep '^+' | sort -u
+    eval "$(filtercommand 'cat "$TODO_FILE"' '' "$@")" | grep -o '[^ ]*+[^ ]\+' | grep '^+' | sort -u
     ;;
 
 "listpri" | "lsp" )