使用rust libc::setsockopt 转换为 c_void

Question

我正在尝试调用 setsockopt但无法弄清楚 c_void 的转换。 IP_HDRINCL 不在 nix 或 socket 包中，所以我必须使用 libc。我以 How to set the socket option SO_REUSEPORT in Rust? 为例

let trueval: c_int = 1;
let ret = setsockopt(mysocket, IPPROTO_IP, IP_HDRINCL, &trueval as *const _ as *const c_void, mem::size_of_val(&trueval) as socklen_t);

error: expected expression, found keyword `const`
  --> src/igmp.rs:30:97
   |
30 |         let ret = setsockopt(mysocket, IPPROTO_IP, IP_HDRINCL, &trueval as *const _ *const c_void, mem::size_of_val(&trueval) as socklen_t);
   |                                                                                      ^^^^^ expected expression

Answer 1

将 trueval 更改为类型 u8 允许代码工作。