Question

We are using an .htaccess in combination with anchor tags to serve files and conceal the server directory structure.

RewriteEngine On
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*)$ /_docu/clients/$1/$2/$3.pdf [NC,L]

For example, all files are stored under /public_html/_docu/clients/ and inside that folder are listed all the clients, and then under each client their projects. However, an anchor tag for a file would read only:

http://mydomain.com/client-name/proj-name/docname.pdf

(the /_docu/clients/ being omitted – there is a good reason for this). The above .htaccess grabs the client-name, proj-name and docname and serves it from the correct folder:

http://mydomain.com/_docu/clients/client-name/proj-name/docname.pdf

whilst preserving in the address bar the incorrect (concealed) directory structure.

I wish to handle the error condition of a document not existing. This should never happen, but it could. Can anyone suggest a way of dealing with this? Can something functionally akin to “if fileexist($1/$2/%3.pdf)” be somehow constructed in an .htaccess file?

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EDIT:

Delayed response as JL’s answer below required research and experimentation. Thanks, Jon, for the gentle push in the right direction but I haven’t got it to work just yet. Here’s what I tried:

RewriteEngine On
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
# check if the requested file exists in the "_docu/clients" directory
RewriteCond %{DOCUMENT_ROOT}/_docu/clients/$1/$2/$3.pdf -f
RewriteRule ^([a-z0-9])/([a-z0-9])/([a-z0-9]*).pdf$ /_docu/clients/$1/$2/$3.pdf [NC,L]
RewriteRule ^(.*)$ /errors/404.php [L]

I thought that what that should do is:

1. If http://mydomain.com/_docu/clients/$1/$2/$3.pdf does not exist,
2. GoTo page http://mydomain.com/errors/404.php

Actual outcome is an “internal server error” message.

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EDIT TWO:

Latest changes:

RewriteEngine On
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_URI} ^/([a-z0-9])/([a-z0-9])/([a-z0-9]*).pdf$
RewriteCond %{DOCUMENT_ROOT}/_data/cli/%1/%2/%3.pdf -f
RewriteRule ^([a-z0-9])/([a-z0-9])/([a-z0-9]*).pdf$ /_data/cli/$1/$2/$3.pdf [NC,L]
RewriteCond %{ENV:REDIRECT_STATUS} !200
RewriteRule ^(.*)$ /metshare/404.php [L]

The problem with this one is that legitimate pages also are directed to 404.php

MESSAGE TO FUTURE READERS:

All of the above concerns were addressed in Jon Lin’s final answer. As issues were detected, he modified his answer until it was a perfect, working solution. I am leaving the above as it is because there are some good ULOs within (unscheduled learning opportunities) for those who want to compare versions.

Answer 1

You need to use a condition like this:

RewriteCond %{DOCUMENT_ROOT}/_docu/clients%{REQUEST_URI} -f

So that your rules looks ssomething like:

RewriteEngine On
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
# check if the requested file exists in the "_docu/clients" directory
RewriteCond %{DOCUMENT_ROOT}/_docu/clients%{REQUEST_URI} -f
RewriteRule ^ /_docu/clients%{REQUEST_URI} [L]

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EDIT: Response to edit in question

You can’t do this:

RewriteCond %{DOCUMENT_ROOT}/_docu/clients/$1/$2/$3.pdf -f

Because the backreferences for $1/$2/$3 don’t exist yet, they are matched in the groupings in your RewriteRule, which hasn’t happened yet at this point. But you can try something like this:

RewriteEngine On
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
# check if the requested file exists in the "_docu/clients" directory
RewriteCond %{REQUEST_URI} ^/([a-z0-9])/([a-z0-9])/([a-z0-9]*).pdf$
RewriteCond %{DOCUMENT_ROOT}/_docu/clients/%1/%2/%3.pdf -f
RewriteRule ^([a-z0-9])/([a-z0-9])/([a-z0-9]*).pdf$ /_docu/clients/$1/$2/$3.pdf [NC,L]

RewriteCond %{ENV:REDIRECT_STATUS} !200
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*)$ /errors/404.php [L]

Essentially creating a match against %{REQUEST_URI} in a previous RewriteCond then using the %N backreferences in the following RewriteCond.