compress string with zlib than download it as .gz file.. how?

[markg85]

hey,

ive created a database backup script which is working fine the way it works now.. the only problem is that the backup function is returning a database backup string. so all the content of the database in a string.. that isnt a big problem when you have a small database but it will get a problem when you have a 10MB db backup.. and that would be the raw .sql file. now to fix that issue i want to compress the string using zlib..

this is the code that i use to create the raw .sql file send it as a download to the user:

        // Disable caching of the current document:
        header('Cache-Control: no-cache, no-store, max-age=0, must-revalidate');
        header('Expires: Mon, 26 Jul 1997 05:00:00 GMT'); // Date in the past
        header('Pragma: no-cache');

    $test = new backupdb;
    $test->db_name = 'magedb';
    $filename = "MageDB_db_backup_" . time() . ".sql";
    //header('Content-Type: text/html; charset=utf-8');
    //header('Content-Type: text/plain');
    header('Content-Type: application/octet-stream');
    header('Content-Disposition: attachment; filename="'.$filename.'"'); 
    header('Content-Transfer-Encoding: binary');
    header('Content-Type: application/force-download');

    //header('Content-Type: text/plain'); // plain text file
    echo $test->structure_dbbackup();
    exit();

but that`s UNCOMPRESSED.. what do i need to change to make it compressed insize a .gz file?
i was thinking of this:

        // Disable caching of the current document:
        header('Cache-Control: no-cache, no-store, max-age=0, must-revalidate');
        header('Expires: Mon, 26 Jul 1997 05:00:00 GMT'); // Date in the past
        header('Pragma: no-cache');

    $test = new backupdb;
    $test->db_name = 'magedb';
    $filename = "MageDB_db_backup_" . time() . ".sql.gz";
    //header('Content-Type: text/html; charset=utf-8');
    //header('Content-Type: text/plain');
    header('Content-Type: application/octet-stream');
    header('Content-Disposition: attachment; filename="'.$filename.'"'); 
    header('Content-Transfer-Encoding: binary');
    header('Content-Type: application/force-download');

    //header('Content-Type: text/plain'); // plain text file
    echo gzcompress($test->structure_dbbackup(), 9);
    exit();

but that isnt working.. the file is being send to me.. and i can download it however i cant open the compressed file.. so i must have made a mistake somewhere.. i just can`t find where.

and i dont want the sql file to be stored on the server in a folder, than create a .gz file and than download that because thats higly insecure.. if someone is bored and tries to find out where the files are stored he could find the location of the database backups (with usernames and (md5 encrypted) passwords).. so the file can`t be stored on the server!!

anyone with some idea`s?
thanx.

[Weedpacket]

Consider using on-the-wire compression, where the client decompresses the file as it is received (so that all the bandwidth is saved, but there isn't that extra step of uncompressing the file manually).
There is a configuration setting for this, but it does compression on all output (and if you're going to do that you might as well use mod_gzip). An alternative is to use [man]ob_gzhandler[/man] to compress the output buffer.

(Incidentally, there is no such MIME type as application/force-download. You're wanting application/octet-stream. Or perhaps application/x-gzip).

[markg85]

thats interesting.. but isnt zlib installed on almost all php servers by default (that`s why i took zlib)?

and i rather have a .gz file send to the user that contains the .sql.. instead of compressing the stream and let the browser do the decompressing.. so any help on that would be gread 🙂

thanx.

[Weedpacket]

So ... did you read up on those two options? They both use zlib.

And you might also try following up that not on the [man]gzcompress[/man] page that says that it's not the same thing as [man]gzencode[/man].

[markg85]

well.. in my search on how to compress something i`ve read up both of those 2 you suggest.

and gzencode did the trick for me 🙂 sometimes you just forget that the solution might be so simple 😛 and i did look over all the options for zlib...

o well.. another question.. as you can see in the code that ive posted earlyer im using header functions to send the file to the user but what i actually want is having a link where i can click on for the database backup.. but is that possible without creating the file on the server and without using ajax? (ajax is fine for me.. just not for database backups because that must work in all browsers)