Function esp_idf_sys::esp_tls_get_bytes_avail

pub unsafe extern "C" fn esp_tls_get_bytes_avail(
    tls: *mut esp_tls_t,
) -> isize

@brief Return the number of application data bytes remaining to be read from the current record

This API is a wrapper over mbedtls’s mbedtls_ssl_get_bytes_avail() API.

@param[in] tls pointer to esp-tls as esp-tls handle.

@return - -1 in case of invalid arg - bytes available in the application data record read buffer