{"id":45325,"date":"2023-02-24T23:13:33","date_gmt":"2023-06-22T20:03:46","guid":{"rendered":"https:\/\/www.silicloud.com\/zh\/blog\/45325-2\/"},"modified":"2024-04-29T16:07:33","modified_gmt":"2024-04-29T08:07:33","slug":"45325-2","status":"publish","type":"post","link":"https:\/\/www.silicloud.com\/zh\/blog\/45325-2\/","title":{"rendered":""},"content":{"rendered":"

C\u306e\u95a2\u6570\u30dd\u30a4\u30f3\u30bf\u3068Rust\u306e\u95a2\u6570\u30dd\u30a4\u30f3\u30bf<\/h2>\n
#include <stdio.h>\r\n<\/span>\r\ntypedef<\/span> void<\/span> (<\/span>*<\/span>rust_callback<\/span>)(<\/span>int<\/span>);<\/span>\r\nrust_callback<\/span> cb<\/span>;<\/span>\r\n\r\nint<\/span> register_callback<\/span>(<\/span>rust_callback<\/span> callback<\/span>)<\/span> {<\/span>\r\n    cb<\/span> =<\/span> callback<\/span>;<\/span>\r\n    return<\/span> 1<\/span>;<\/span>\r\n}<\/span>\r\n\r\nvoid<\/span> trigger_callback<\/span>()<\/span> {<\/span>\r\n  if<\/span> (<\/span>cb<\/span> !=<\/span> NULL<\/span>)<\/span> {<\/span>\r\n    cb<\/span>(<\/span>7<\/span>);<\/span>\r\n  }<\/span> else<\/span> {<\/span>\r\n    printf<\/span>(<\/span>\"callback function is not set!\"<\/span>);<\/span>\r\n  }<\/span>\r\n}<\/span>\r\n<\/code><\/pre>\n
(\u4ed6\u8a00\u8a9e\u95a2\u6570\u30a4\u30f3\u30bf\u30fc\u30d5\u30a7\u30a4\u30b9\u306e\u3082\u306e\u3092\u6539\u5909)
\n\u3053\u306e\u3088\u3046\u306a\u30b3\u30fc\u30eb\u30d0\u30c3\u30af\u3092\u6271\u3046C\u306e\u30e9\u30a4\u30d6\u30e9\u30ea\u3092\u547c\u3073\u51fa\u3059Rust\u306eFFI\u3092\u4f5c\u308a\u307e\u3057\u3087\u3046\u3002<\/p>\n
\u4ed6\u8a00\u8a9e\u95a2\u6570\u30a4\u30f3\u30bf\u30fc\u30d5\u30a7\u30a4\u30b9\u3067\u306f\u4ee5\u4e0b\u306e\u3088\u3046\u306b\u4f5c\u308b\u3088\u3046\u306b\u66f8\u3044\u3066\u3042\u308a\u307e\u3059\uff1a<\/p>\n
extern<\/span> fn<\/span> callback<\/span>(<\/span>a<\/span>:<\/span> i32<\/span>)<\/span> {<\/span>\r\n    println!<\/span>(<\/span>\"I'm called from C with value {0}\"<\/span>,<\/span> a<\/span>);<\/span>\r\n}<\/span>\r\n\r\n#[link(name<\/span> =<\/span> \"ext\"<\/span>)]<\/span>\r\nextern<\/span> {<\/span>\r\n   fn<\/span> register_callback<\/span>(<\/span>cb<\/span>:<\/span> extern<\/span> fn<\/span>(<\/span>i32<\/span>))<\/span> -><\/span> i32<\/span>;<\/span>\r\n   fn<\/span> trigger_callback<\/span>();<\/span>\r\n}<\/span>\r\n\r\nfn<\/span> main<\/span>()<\/span> {<\/span>\r\n    unsafe<\/span> {<\/span>\r\n        register_callback<\/span>(<\/span>callback<\/span>);<\/span>\r\n        trigger_callback<\/span>();<\/span> \/\/ Triggers the callback<\/span>\r\n    }<\/span>\r\n}<\/span>\r\n<\/code><\/pre>\n
\u3053\u308c\u306f\u52ff\u8ad6\u52d5\u4f5c\u3057\u307e\u3059\u3002\u3057\u304b\u3057\u3001\u3053\u308c\u306f\u672c\u5f53\u306bC\u306eAPI\u3092\u6b63\u3057\u304f\u8e0f\u8972\u3067\u304d\u3066\u3044\u308b\u3067\u3057\u3087\u3046\u304b\uff1f<\/p>\n
\u5143\u306eC\u306e\u30d7\u30ed\u30b0\u30e9\u30e0\u306b\u304a\u3044\u3066\u3001cb\u306b\u306fNULL\u3092\u5165\u308c\u3066\u3082\u3044\u3044\u306f\u305a\u3067\u3059\u3002C\u306eAPI\u3067\u306f\u3001\u30b3\u30fc\u30eb\u30d0\u30c3\u30af\u304c\u5fc5\u8981\u306a\u3044\u5834\u5408\u306f\u95a2\u6570\u30dd\u30a4\u30f3\u30bf\u3068\u3057\u3066NULL\u3092\u5165\u308c\u308b\u3053\u3068\u306f\u3088\u304f\u884c\u308f\u308c\u307e\u3059\u3002<\/p>\n
register_callback<\/span>(<\/span>NULL<\/span>);<\/span>  \/\/ callback\u306f\u767b\u9332\u3057\u306a\u3044<\/span>\r\n<\/code><\/pre>\n
\u3055\u3066\u3053\u3053\u3067\u554f\u984c\u306b\u306a\u308b\u306e\u306fRust\u5074\u306eregister_callback\u306e\u5b9a\u7fa9\u3067\u3059\u3002NULL\u306b\u76f8\u5f53\u3059\u308b\u306e\u306fstd::ptr::null_mut()\u306a\u306e\u3067\u3053\u308c\u3092\u4ee3\u5165\u3057\u3066\u307f\u307e\u3057\u3087\u3046\uff1a<\/p>\n
use<\/span> std<\/span>::<\/span>ptr<\/span>::<\/span>null_mut<\/span>;<\/span>\r\nextern<\/span> \"C\"<\/span> {<\/span>\r\n    fn<\/span> register_callback<\/span>(<\/span>cb<\/span>:<\/span> extern<\/span> \"C\"<\/span> fn<\/span>(<\/span>i32<\/span>))<\/span> -><\/span> i32<\/span>;<\/span>\r\n}<\/span>\r\nfn<\/span> main<\/span>()<\/span> {<\/span>\r\n    unsafe<\/span> {<\/span> register_callback<\/span>(<\/span>null_mut<\/span>())<\/span> };<\/span>\r\n}<\/span>\r\n<\/code><\/pre>\n
\u3053\u308c\u306f\u30b3\u30f3\u30d1\u30a4\u30eb\u3067\u304d\u307e\u305b\u3093\uff1a<\/p>\n
   |\r\n12 |     unsafe { register_callback(null_mut()) };\r\n   |                                ^^^^^^^^^^ expected fn pointer, found *-ptr\r\n   |\r\n   = note: expected type `extern \"C\" fn(i32)`\r\n              found type `*mut _`\r\n<\/code><\/pre>\n
\u3053\u308c\u306fas\u3067\u660e\u793a\u7684\u306b\u5909\u63db\u3057\u3088\u3046\u3068\u3057\u3066\u3082\u3067\u304d\u307e\u305b\u3093\u3002<\/p>\n
Nullable\u306a\u95a2\u6570\u30dd\u30a4\u30f3\u30bf<\/h2>\n
\u3068\u3053\u308d\u3067C\u304b\u3089Rust\u306e\u30d0\u30a4\u30f3\u30c7\u30a3\u30f3\u30b0\u3092\u751f\u6210\u3067\u304d\u308brust-bindgen\u306f\u3069\u3046\u3084\u3063\u3066\u3044\u308b\u306e\u3067\u3057\u3087\u3046\u304b\uff1f\u4e0a\u306eC\u306e\u30b3\u30fc\u30c9\u3092bindgen\u3057\u3066\u307f\u307e\u3057\u3087\u3046<\/p>\n
pub<\/span> type<\/span> rust_callback<\/span> =<\/span> ::<\/span>std<\/span>::<\/span>option<\/span>::<\/span>Option<\/span><<\/span>unsafe<\/span> extern<\/span> \"C\"<\/span> fn<\/span>(<\/span>arg1<\/span>:<\/span> ::<\/span>std<\/span>::<\/span>os<\/span>::<\/span>raw<\/span>::<\/span>c_int<\/span>)<\/span>><\/span>;<\/span>\r\nextern<\/span> \"C\"<\/span> {<\/span>\r\n    #[link_name<\/span> =<\/span> \"<\/span>\\<\/span>u{1}cb\"<\/span>]<\/span>\r\n    pub<\/span> static<\/span> mut<\/span> cb<\/span>:<\/span> rust_callback<\/span>;<\/span>\r\n}<\/span>\r\nextern<\/span> \"C\"<\/span> {<\/span>\r\n    pub<\/span> fn<\/span> register_callback<\/span>(<\/span>callback<\/span>:<\/span> rust_callback<\/span>)<\/span> -><\/span> ::<\/span>std<\/span>::<\/span>os<\/span>::<\/span>raw<\/span>::<\/span>c_int<\/span>;<\/span>\r\n}<\/span>\r\n<\/code><\/pre>\n
#include\u304c\u3042\u308b\u306e\u3067\u4f59\u8a08\u306a\u90e8\u5206\u304c\u305f\u304f\u3055\u3093\u51fa\u3066\u304d\u307e\u3059\u304c\u3001\u8a72\u5f53\u90e8\u5206\u306f\u3053\u308c\u3060\u3051\u3067\u3059\u3002
\nOption\u3092\u4f7f\u3048\u3070\u826f\u3044\u3088\u3046\u3067\u3059\u306d\u3002<\/p>\n
extern<\/span> \"C\"<\/span> fn<\/span> callback<\/span>(<\/span>a<\/span>:<\/span> i32<\/span>)<\/span> {<\/span>\r\n    println!<\/span>(<\/span>\"I'm called from C with value {0}\"<\/span>,<\/span> a<\/span>);<\/span>\r\n}<\/span>\r\n\r\n#[link(name=<\/span>\"ext\"<\/span>)]<\/span>\r\nextern<\/span> \"C\"<\/span> {<\/span>\r\n    fn<\/span> register_callback<\/span>(<\/span>cb<\/span>:<\/span> Option<\/span><<\/span>extern<\/span> \"C\"<\/span> fn<\/span>(<\/span>i32<\/span>)<\/span>><\/span>)<\/span> -><\/span> i32<\/span>;<\/span>\r\n    fn<\/span> trigger_callback<\/span>();<\/span>\r\n}<\/span>\r\n\r\nfn<\/span> main<\/span>()<\/span> {<\/span>\r\n    unsafe<\/span> {<\/span>\r\n        register_callback<\/span>(<\/span>Some<\/span>(<\/span>callback<\/span>));<\/span>\r\n        trigger_callback<\/span>();<\/span>\r\n    }<\/span>\r\n    unsafe<\/span> {<\/span>\r\n        register_callback<\/span>(<\/span>None<\/span>);<\/span>\r\n        trigger_callback<\/span>();<\/span>\r\n    }<\/span>\r\n}<\/span>\r\n<\/code><\/pre>\n
$ cargo run\r\nI'm called from C with value 7\r\ncallback function is not set!\r\n<\/code><\/pre>\n
\u4e0a\u624b\u304f\u3067\u304d\u307e\u3057\u305f(\/\u30fb\u03c9\u30fb)\/<\/p>\n
\u53c2\u8003<\/h2>\n
    Rust\u306e\u95a2\u6570\u30dd\u30a4\u30f3\u30bf\u306e\u843d\u3068\u3057\u7a74<\/ul>\n
    \u4ee5\u4e0a\u306e\u30bd\u30fc\u30b9\u30b3\u30fc\u30c9\u306f https:\/\/github.com\/termoshtt\/nullable_fn_ptr \u306b\u3042\u308a\u307e\u3059<\/p>\n","protected":false},"excerpt":{"rendered":"
    C\u306e\u95a2\u6570\u30dd\u30a4\u30f3\u30bf\u3068Rust\u306e\u95a2\u6570\u30dd\u30a4\u30f3\u30bf #include <stdio.h> typedef v […]<\/p>\n","protected":false},"author":6,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-45325","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"yoast_head":"\n- Blog - Silicon Cloud<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.silicloud.com\/zh\/blog\/45325-2\/\" \/>\n<meta property=\"og:locale\" content=\"zh_CN\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:description\" content=\"C\u306e\u95a2\u6570\u30dd\u30a4\u30f3\u30bf\u3068Rust\u306e\u95a2\u6570\u30dd\u30a4\u30f3\u30bf #include <stdio.h> typedef v […]\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.silicloud.com\/zh\/blog\/45325-2\/\" \/>\n<meta property=\"og:site_name\" content=\"Blog - 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