too many redirects in htaccess - apache

Question

I want to accomplish the following:
redirect non-www to www for all users
redirect desktop users to www.example.com/homepage
redirect mobile users to www.example.com/m
hide /homepage and /m from url so users will see www.example.com only
Here is my htaccess code. I am having a lot of problems with it, like things not redirecting to /m, and iphone users see "too many redirects", and sometimes desktop users are taken to /m even though they should be taken to /homepage.
RewriteEngine On
RewriteCond %{HTTP_HOST} ^example.com [NC]
RewriteRule ^(.*)$ http://www.example.com/$1 [L,R=301]
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteRule ^$ /homepage/ [R=301]
</IfModule>
RewriteCond %{HTTP_USER_AGENT} ^.*iPad.*$
RewriteRule ^(.*)$ http://www.example.com/m [R=301]
RewriteCond %{HTTP_USER_AGENT} ^.*iPod.*$
RewriteRule ^(.*)$ http://www.example.com/m [R=301]
RewriteCond %{HTTP_USER_AGENT} ^.*iPhone.*$
RewriteRule ^(.*)$ http://www.example.com/m [R=301]
RewriteCond %{HTTP_USER_AGENT} ^.*iemobile.*$
RewriteRule ^(.*)$ http://www.example.com/m [R=301]
RewriteCond %{HTTP_USER_AGENT} ^.*blackberry.*$
RewriteRule ^(.*)$ http://www.example.com/m [R=301]
RewriteCond %{HTTP_USER_AGENT} ^.*Android.*$
RewriteRule ^(.*)$ http://www.example.com/m [R=301]

Answer 1

This will give you too many redirects because you're only looking at the user agent, not the URI that's being requested, so every time a mobile user agent matches you continually redirect them to www.example.com/m. You can also add all the user agents into a single regex to reduce the number of rules you need to maintain.
You need to add a condition to look at the REQUEST_URI. Something like to the following should do:
RewriteCond %{HTTP_USER_AGENT} ^.*(ip(ad|od|hone)|blackberry|iemobile|android).*$ [NC]
RewriteCond %{REQUEST_URI} !^/m/.*
RewriteRule ^.*$ http://www.example.com/m [R=301,L]