POSIX sh equivalent for Bash’s printf %q

Question

Suppose I have a #!/bin/sh script which can take a variety of positional parameters, some of which may include spaces, either/both kinds of quotes, etc. I want

Answer 1

The following seems to work with everything I have thrown at it so far, including spaces, both kinds of quotes and a variety of other metacharacters, and embedded newlines:

#!/bin/sh
quote() {
    echo "$1" | sed "s/'/'\"'\"'/g"
}
args=
for arg in "$@"
do
    argq="'"`quote "$arg"`"'"
    args="$argq $args"
done
eval "ls $args"