# lib.rs - source
Source of the Rust file `/home/runner/.cargo/registry/src/github.com-1ecc6299db9ec823/ctor-0.1.20/src/lib.rs`.
Keywords: rust, rustlang, rust-lang

      1
      2
      3
      4
      5
      6
      7
      8
      9
     10
     11
     12
     13
     14
     15
     16
     17
     18
     19
     20
     21
     22
     23
     24
     25
     26
     27
     28
     29
     30
     31
     32
     33
     34
     35
     36
     37
     38
     39
     40
     41
     42
     43
     44
     45
     46
     47
     48
     49
     50
     51
     52
     53
     54
     55
     56
     57
     58
     59
     60
     61
     62
     63
     64
     65
     66
     67
     68
     69
     70
     71
     72
     73
     74
     75
     76
     77
     78
     79
     80
     81
     82
     83
     84
     85
     86
     87
     88
     89
     90
     91
     92
     93
     94
     95
     96
     97
     98
     99
    100
    101
    102
    103
    104
    105
    106
    107
    108
    109
    110
    111
    112
    113
    114
    115
    116
    117
    118
    119
    120
    121
    122
    123
    124
    125
    126
    127
    128
    129
    130
    131
    132
    133
    134
    135
    136
    137
    138
    139
    140
    141
    142
    143
    144
    145
    146
    147
    148
    149
    150
    151
    152
    153
    154
    155
    156
    157
    158
    159
    160
    161
    162
    163
    164
    165
    166
    167
    168
    169
    170
    171
    172
    173
    174
    175
    176
    177
    178
    179
    180
    181
    182
    183
    184
    185
    186
    187
    188
    189
    190
    191
    192
    193
    194
    195
    196
    197
    198
    199
    200
    201
    202
    203
    204
    205
    206
    207
    208
    209
    210
    211
    212
    213
    214
    215
    216
    217
    218
    219
    220
    221
    222
    223
    224
    225
    226
    227
    228
    229
    230
    231
    232
    233
    234
    235
    236
    237
    238
    239
    240
    241
    242
    243
    244
    245
    246
    247
    248
    249
    250
    251
    252
    253
    254
    255
    256
    257
    258
    259
    260
    261
    262
    263
    264
    265
    266
    267
    268
    269
    270
    271
    272
    273
    274
    275
    276
    277
    278
    279
    280
    281
    282
    283
    284
    285
    286
    287
    288
    289
    290
    291
    292
    293
    294
    295
    296
    297
    298
    299
    300
    301
    302
    303
    304
    305
    306
    307
    308
    309
    310
    311
    312
    313
    314
    315
    316
    317
    318
    319
    320
    321
    322
    323
    324
    325
    326
    327
    328
    329
    330
    331
    332
    333
    334
    335
    336
    337
    338
    339
    340
    341
    342
    343
    344
    345
    346
    347
    348
    349
    350
    351
    352
    353
    354
    355
    356
    357
    358
    359
    360
    361
    362
    363
    364
    365
    366
    367
    368
    369
    370
    371
    372
    373
    374
    375
    376
    377
    378
    379
    380
    381
    382
    383
    384
    385
    386
    387
    388
    389
    390
    391
    392
    393
    394

    #![recursion_limit = "256"]

    //! Procedural macro for defining global constructor/destructor functions.
    //!
    //! This provides module initialization/teardown functions for Rust (like
    //! `__attribute__((constructor))` in C/C++) for Linux, OSX, and Windows via
    //! the `#[ctor]` and `#[dtor]` macros.
    //!
    //! This library works and has been tested for Linux, OSX and Windows. This
    //! library will also work as expected in both `bin` and `cdylib` outputs,
    //! ie: the `ctor` and `dtor` will run at executable or library
    //! startup/shutdown respectively.
    //!
    //! This library currently requires Rust > `1.31.0` at a minimum for the
    //! procedural macro support.

    // Code note:

    // You might wonder why we don't use `__attribute__((destructor))`/etc for
    // dtor. Unfortunately mingw doesn't appear to properly support section-based
    // hooks for shutdown, ie:

    // https://github.com/Alexpux/mingw-w64/blob/d0d7f784833bbb0b2d279310ddc6afb52fe47a46/mingw-w64-crt/crt/crtdll.c

    extern crate proc_macro;
    extern crate syn;
    #[macro_use]
    extern crate quote;

    use proc_macro::TokenStream;

    /// Marks a function or static variable as a library/executable constructor.
    /// This uses OS-specific linker sections to call a specific function at
    /// load time.
    ///
    /// Multiple startup functions/statics are supported, but the invocation order is not
    /// guaranteed.
    ///
    /// # Examples
    ///
    /// Print a startup message:
    ///
    /// ```rust
    /// # extern crate ctor;
    /// # use ctor::*;
    /// #[ctor]
    /// fn foo() {
    ///   println!("Hello, world!");
    /// }
    ///
    /// # fn main() {
    /// println!("main()");
    /// # }
    /// ```
    ///
    /// Make changes to `static` variables:
    ///
    /// ```rust
    /// # extern crate ctor;
    /// # use ctor::*;
    /// # use std::sync::atomic::{AtomicBool, Ordering};
    /// static INITED: AtomicBool = AtomicBool::new(false);
    ///
    /// #[ctor]
    /// fn foo() {
    ///   INITED.store(true, Ordering::SeqCst);
    /// }
    /// ```
    ///
    /// Initialize a `HashMap` at startup time:
    ///
    /// ```rust
    /// # extern crate ctor;
    /// # use std::collections::HashMap;
    /// # use ctor::*;
    /// #[ctor]
    /// static STATIC_CTOR: HashMap<u32, String> = {
    ///   let mut m = HashMap::new();
    ///   for i in 0..100 {
    ///     m.insert(i, format!("x*100={}", i*100));
    ///   }
    ///   m
    /// };
    ///
    /// # pub fn main() {
    /// #   assert_eq!(STATIC_CTOR.len(), 100);
    /// #   assert_eq!(STATIC_CTOR[&20], "x*100=2000");
    /// # }
    /// ```
    ///
    /// # Details
    ///
    /// The `#[ctor]` macro makes use of linker sections to ensure that a
    /// function is run at startup time.
    ///
    /// The above example translates into the following Rust code (approximately):
    ///
    ///```rust
    /// #[used]
    /// #[cfg_attr(any(target_os = "linux", target_os = "android"), link_section = ".init_array")]
    /// #[cfg_attr(target_os = "freebsd", link_section = ".init_array")]
    /// #[cfg_attr(target_os = "netbsd", link_section = ".init_array")]
    /// #[cfg_attr(target_os = "openbsd", link_section = ".init_array")]
    /// #[cfg_attr(target_os = "illumos", link_section = ".init_array")]
    /// #[cfg_attr(any(target_os = "macos", target_os = "ios"), link_section = "__DATA,__mod_init_func")]
    /// #[cfg_attr(target_os = "windows", link_section = ".CRT$XCU")]
    /// static FOO: extern fn() = {
    ///   #[cfg_attr(any(target_os = "linux", target_os = "android"), link_section = ".text.startup")]
    ///   extern fn foo() { /* ... */ };
    ///   foo
    /// };
    /// ```
    #[proc_macro_attribute]
    pub fn ctor(_attribute: TokenStream, function: TokenStream) -> TokenStream {
        let item: syn::Item = syn::parse_macro_input!(function);
        if let syn::Item::Fn(function) = item {
            validate_item("ctor", &function);

            let syn::ItemFn {
                attrs,
                block,
                vis,
                sig:
                    syn::Signature {
                        ident,
                        unsafety,
                        constness,
                        abi,
                        ..
                    },
                ..
            } = function;

            // Linux/ELF: https://www.exploit-db.com/papers/13234

            // Mac details: https://blog.timac.org/2016/0716-constructor-and-destructor-attributes/

            // Why .CRT$XCU on Windows? https://www.cnblogs.com/sunkang/archive/2011/05/24/2055635.html
            // 'I'=C init, 'C'=C++ init, 'P'=Pre-terminators and 'T'=Terminators

            let ctor_ident =
                syn::parse_str::<syn::Ident>(format!("{}___rust_ctor___ctor", ident).as_ref())
                    .expect("Unable to create identifier");

            let output = quote!(
                #[cfg(not(any(target_os = "linux", target_os = "android", target_os = "freebsd", target_os = "netbsd", target_os = "openbsd", target_os = "illumos", target_os = "macos", target_os = "ios", windows)))]
                compile_error!("#[ctor] is not supported on the current target");

                #(#attrs)*
                #vis #unsafety extern #abi #constness fn #ident() #block

                #[used]
                #[allow(non_upper_case_globals)]
                #[cfg_attr(any(target_os = "linux", target_os = "android"), link_section = ".init_array")]
                #[cfg_attr(target_os = "freebsd", link_section = ".init_array")]
                #[cfg_attr(target_os = "netbsd", link_section = ".init_array")]
                #[cfg_attr(target_os = "openbsd", link_section = ".init_array")]
                #[cfg_attr(target_os = "illumos", link_section = ".init_array")]
                #[cfg_attr(any(target_os = "macos", target_os = "ios"), link_section = "__DATA,__mod_init_func")]
                #[cfg_attr(windows, link_section = ".CRT$XCU")]
                static #ctor_ident
                :
                unsafe extern "C" fn() =
                {
                    #[cfg_attr(any(target_os = "linux", target_os = "android"), link_section = ".text.startup")]
                    unsafe extern "C" fn #ctor_ident() { #ident() };
                    #ctor_ident
                }
                ;
            );

            // eprintln!("{}", output);

            output.into()
        } else if let syn::Item::Static(var) = item {
            let syn::ItemStatic {
                ident,
                mutability,
                expr,
                attrs,
                ty,
                vis,
                ..
            } = var;

            if let Some(_) = mutability {
                panic!("#[ctor]-annotated static objects must not be mutable");
            }

            if attrs.iter().any(|attr| {
                attr.path
                    .segments
                    .iter()
                    .any(|segment| segment.ident == "no_mangle")
            }) {
                panic!("#[ctor]-annotated static objects do not support #[no_mangle]");
            }

            let ctor_ident =
                syn::parse_str::<syn::Ident>(format!("{}___rust_ctor___ctor", ident).as_ref())
                    .expect("Unable to create identifier");
            let storage_ident =
                syn::parse_str::<syn::Ident>(format!("{}___rust_ctor___storage", ident).as_ref())
                    .expect("Unable to create identifier");

            let output = quote!(
                #[cfg(not(any(target_os = "linux", target_os = "android", target_os = "freebsd", target_os = "netbsd", target_os = "openbsd", target_os = "illumos", target_os = "macos", target_os = "ios", windows)))]
                compile_error!("#[ctor] is not supported on the current target");

                // This is mutable, but only by this macro code!
                static mut #storage_ident: Option<#ty> = None;

                #[doc(hidden)]
                #[allow(non_camel_case_types)]
                #vis struct #ident<T> {
                    _data: core::marker::PhantomData<T>
                }

                #(#attrs)*
                #vis static #ident: #ident<#ty> = #ident {
                    _data: core::marker::PhantomData::<#ty>
                };

                impl core::ops::Deref for #ident<#ty> {
                    type Target = #ty;
                    fn deref(&self) -> &'static #ty {
                        unsafe {
                            #storage_ident.as_ref().unwrap()
                        }
                    }
                }

                #[used]
                #[allow(non_upper_case_globals)]
                #[cfg_attr(any(target_os = "linux", target_os = "android"), link_section = ".init_array")]
                #[cfg_attr(target_os = "freebsd", link_section = ".init_array")]
                #[cfg_attr(target_os = "netbsd", link_section = ".init_array")]
                #[cfg_attr(target_os = "openbsd", link_section = ".init_array")]
                #[cfg_attr(target_os = "illumos", link_section = ".init_array")]
                #[cfg_attr(any(target_os = "macos", target_os = "ios"), link_section = "__DATA,__mod_init_func")]
                #[cfg_attr(windows, link_section = ".CRT$XCU")]
                static #ctor_ident
                :
                unsafe extern "C" fn() = {
                    #[cfg_attr(any(target_os = "linux", target_os = "android"), link_section = ".text.startup")]
                    unsafe extern "C" fn initer() {
                        #storage_ident = Some(#expr);
                    }; initer }
                ;
            );

            // eprintln!("{}", output);

            output.into()
        } else {
            panic!("#[ctor] items must be functions or static globals");
        }
    }

    /// Marks a function as a library/executable destructor. This uses OS-specific
    /// linker sections to call a specific function at termination time.
    ///
    /// Multiple shutdown functions are supported, but the invocation order is not
    /// guaranteed.
    ///
    /// `sys_common::at_exit` is usually a better solution for shutdown handling, as
    /// it allows you to use `stdout` in your handlers.
    ///
    /// ```rust
    /// # extern crate ctor;
    /// # use ctor::*;
    /// # fn main() {}
    ///
    /// #[dtor]
    /// fn shutdown() {
    ///   /* ... */
    /// }
    /// ```
    #[proc_macro_attribute]
    pub fn dtor(_attribute: TokenStream, function: TokenStream) -> TokenStream {
        let function: syn::ItemFn = syn::parse_macro_input!(function);
        validate_item("dtor", &function);

        let syn::ItemFn {
            attrs,
            block,
            vis,
            sig:
                syn::Signature {
                    ident,
                    unsafety,
                    constness,
                    abi,
                    ..
                },
            ..
        } = function;

        let mod_ident =
            syn::parse_str::<syn::Ident>(format!("{}___rust_dtor___mod", ident).as_ref())
                .expect("Unable to create identifier");

        let dtor_ident =
            syn::parse_str::<syn::Ident>(format!("{}___rust_dtor___dtor", ident).as_ref())
                .expect("Unable to create identifier");

        let output = quote!(
            #[cfg(not(any(target_os = "linux", target_os = "android", target_os = "freebsd", target_os = "netbsd", target_os = "openbsd", target_os = "illumos", target_os = "macos", target_os = "ios", windows)))]
            compile_error!("#[dtor] is not supported on the current target");

            #(#attrs)*
            #vis #unsafety extern #abi #constness fn #ident() #block

            // Targets that use `atexit`.
            #[cfg(not(any(
                target_os = "macos",
                target_os = "ios",
            )))]
            mod #mod_ident {
                use super::#ident;

                // Avoid a dep on libc by linking directly
                extern "C" {
                    fn atexit(cb: unsafe extern fn());
                }

                #[used]
                #[allow(non_upper_case_globals)]
                #[cfg_attr(any(target_os = "linux", target_os = "android"), link_section = ".init_array")]
                #[cfg_attr(target_os = "freebsd", link_section = ".init_array")]
                #[cfg_attr(target_os = "netbsd", link_section = ".init_array")]
                #[cfg_attr(target_os = "openbsd", link_section = ".init_array")]
                #[cfg_attr(target_os = "illumos", link_section = ".init_array")]
                #[cfg_attr(windows, link_section = ".CRT$XCU")]
                static __dtor_export
                :
                unsafe extern "C" fn() =
                {
                    #[cfg_attr(any(target_os = "linux", target_os = "android"), link_section = ".text.exit")]
                    unsafe extern "C" fn #dtor_ident() { #ident() };
                    #[cfg_attr(any(target_os = "linux", target_os = "android"), link_section = ".text.startup")]
                    unsafe extern fn __dtor_atexit() {
                        atexit(#dtor_ident);
                    };
                    __dtor_atexit
                };
            }

            // Targets that don't rely on `atexit`.
            #[cfg(any(
                target_os = "macos",
                target_os = "ios",
            ))]
            mod #mod_ident {
                use super::#ident;

                #[used]
                #[allow(non_upper_case_globals)]
                #[cfg_attr(any(target_os = "macos", target_os = "ios"), link_section = "__DATA,__mod_term_func")]
                static __dtor_export
                :
                unsafe extern "C" fn() =
                {
                    unsafe extern fn __dtor() { #ident() };
                    __dtor
                };
            }
        );

        // eprintln!("{}", output);

        output.into()
    }

    fn validate_item(typ: &str, item: &syn::ItemFn) {
        let syn::ItemFn { vis, sig, .. } = item;

        // Ensure that visibility modifier is not present
        match vis {
            syn::Visibility::Inherited => {}
            _ => panic!("#[{}] methods must not have visibility modifiers", typ),
        }

        // No parameters allowed
        if sig.inputs.len() > 0 {
            panic!("#[{}] methods may not have parameters", typ);
        }

        // No return type allowed
        match sig.output {
            syn::ReturnType::Default => {}
            _ => panic!("#[{}] methods must not have return types", typ),
        }
    }