Method and apparatus for performing antivirus tasks in a mobile wireless device

A method of performing an antivirus task in a mobile wireless device, the method comprising:

• replacing a first instruction in an original function code with a reference to an antivirus function code in a mobile wireless device running an embedded operating system;
• creating a stub code comprising the first instruction from the original function code;
• redirecting a call received by the original function code to the antivirus function code by way of the reference to the antivirus function code;
• performing an antivirus task with the antivirus function code;
• executing the first instruction in the stub code after performing the antivirus task;
• executing a second instruction in the stub code to execute a third instruction in the original function code;
• restoring the original function code to its previous form prior to replacing the first instruction in the original function code after assuring that each call redirected to the antivirus function code has exited the antivirus function code;
• wherein assuring that each call redirected to the antivirus function code has exited the antivirus function code comprises incrementing a counter when a call is redirected to the antivirus function code, decrementing the counter when the call is forwarded to the original function code;
• and assuring the counter is zero before restoring the original function code to its previous form.