Replace exec() function in compression operation

For the site I am working for, Exec() operation is not permitted :

exec() has been disabled for security reasons dans site_path/sites/all/modules/db_maintenance/db_maintenance.module at line 500.

Guess this is due to server configuration.
I have a quick look at Backup and Migrate module to understand how the compression operation is done because it work well and I noticed exec function is not used.
It could be a usefull improvement to 1/ replace the exec() function by such code or 2/ keep exec() function and add such code with a selector.