Question

What happens when an application calls an operating system API?

a.

The user-mode API performs basic parameter validation checks and calls into the kernel to actually perform the requested operation.

b.

The kernel-mode API performs basic parameter validation checks and calls into the user-mode to actually perform the requested operation.

c.

The user-mode API directly calls a kernel function.

d.

The kernel-mode API directly calls a user-mode function.

Posted under Reverse Engineering

Answer: (a).The user-mode API performs basic parameter validation checks and calls into the kernel to actually perform the requested operation. Explanation:When an application calls an operating system API, the user-mode API usually performs basic parameter validation checks and calls into the kernel to actually perform the requested operation.

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