Recursion and shell functions

[DervishD <raul@pleyades.net>]

    Hi all :))

    First of all, please excuse this a-bit-off-topic question, but I
need to know if a feature available in zsh is portable.

    I need to do recursion in a directory tree and have two options;
first one is doing a 'for' loop recursively calling the shell
function which performs the actions:

    function () {

        for item
        do
            if [ -d $item ]
            then
                do_some_action
                chmod u+w $item
                cd $item
                function           <-- Overwrites 'item', of course
                chmod u-w $item    <-- Oh-oh... $item is not as before...
                ...
            fi 
        fi
        ...
    }

    Second is using 'find' to do the proper operations, although I
don't want the piece of software dependent on 'find'. The problem is
if I can do recursion safely (well, portably), if it is supported by
POSIX (I can't find a word about it in SuSv3) or at least if it is
common practice: don't want to find a tiny non-interactive shell
failing because of this...

    Just in case you can help me, I need to copy a hierarchy from one
place to another (where some files can be already present) setting
permissions in the process. Other solution I'm considering is doing a
'cp -fpR' over the tree and after that the recursion above for
setting the permissions. This may seems unreasonable (two
recursions...) but it's necessary since the recursive function call
overwrites local variables, and I *cannot* set them as local, since
'local' is not a portable keyword :((( I need 

    Suggestions welcome and thanks in advance :))

    Raúl