CODEWITHSUNDEEP
phpftp
Paul Macey
Paul Macey

Reputation: 113

Check files on remote FTP server for duplicate content with PHP

I've written a script that transfers local files into a folder structure on a remote FTP server with PHP. I'm currently using ftp_connect() to connect to the remote server and ftp_put() to transfer the file, in this case, a CSV file.

My question is, how would one verify that a file's contents (on the remote FTP server) are not a duplicate of the local file's contents? Is there any way to parse the contents of the remote file in question, as well as a local version and then compare them using a PHP function?

I have tried comparing the filesizes of the local file using filesize() and the remote file using ftp_size(), respectively. However, even with different data, but the same number of characters it generates a false positive for duplication as the file-sizes are the same number of bytes.

Please note, the FTP in question is not under my control, so I can't put any scripts on the remote server.

Update

Thanks to both Mark and gafreax, here is the final working code:

$temp_local_file = fopen($conf['absolute_installation_path'] . 'data/temp/ftp_temp.csv', 'w');
if ( ftp_fget($connection, $temp_local_file, $remote_filename, FTP_ASCII) ) {
    $temp_local_stream = file_get_contents($conf['absolute_installation_path'] . 'data/temp/ftp_temp.csv');
    $local_stream = file_get_contents($conf['absolute_installation_path'] . $local_filename);
    $temp_hash = md5($temp_local_stream);
    $local_hash = md5($local_stream);
    if($temp_hash !== $local_hash) {
        $remote_file_duplicate = FALSE;
    } else {
        $remote_file_duplicate = TRUE;
    }                       
}

Upvotes: 2

Views: 1691

Answers (2)

Linblow
Linblow

Reputation: 479

You could also compare the last modified time of each file. You'd upload the local file only if it is more recent than the remote one. See filemtime and ftp_mdtm. Both of those return a UNIX timestamp you can easily compare. This is faster than getting the file contents and calculating a hash.

Upvotes: 1

gafreax
gafreax

Reputation: 410

You can use hashing function like md5 and check against two generated md5 if they match.

For example:

 $a = file_get_contents('a_local');
 $b = file_get_contents('b_local');
 $a_hash = md5($a);
 $b_hash = md5($b);
 if($a_hash !== $b_hash) 
    echo "File differ";
 else 
    echo "File are the same";

The md5 function is useful to avoid problem on reading strange data on file

Upvotes: 1

Related Questions