函数 av_size_mult 

pub unsafe extern "C" fn av_size_mult(
    a: usize,
    b: usize,
    r: *mut usize,
) -> c_int

Multiply two size_t values checking for overflow.

@param[in] a Operand of multiplication @param[in] b Operand of multiplication @param[out] r Pointer to the result of the operation @return 0 on success, AVERROR(EINVAL) on overflow