TypeDef Basic explanation

Question

typedef size_t (CCAUTH_CALL *ccauth_sign_callback)(struct ccauth_handle *handle, const unsigned char *plain, size_t
size, unsigned char *buffer, size_t buffer_size); 

could you please explain the line. I am getting this typedef line.

Answer 1

It's a typedef for a function pointer.

It creates a type called ccauth_sign_callback which is a pointer to a function with arguments of types struct ccauth_handle *, const unsigned char *, size_t, unsigned char *, and size_t, and returns a value of type size_t

CCAUTH_CALL looks like a macro. It probably adds compiler-specific attributes.