link_section/
lib.rs

1#![doc = include_str!("../README.md")]
2#![allow(unsafe_code)]
3
4/// Declarative forms of the `#[section]` and `#[in_section(...)]` macros.
5///
6/// The declarative forms wrap and parse a proc_macro-like syntax like so, and
7/// are identical in expansion to the undecorated procedural macros. The
8/// declarative forms support the same attribute parameters as the procedural
9/// macros.
10pub mod declarative {
11    pub use crate::__in_section_parse as in_section;
12    pub use crate::__section_parse as section;
13}
14
15#[doc(hidden)]
16pub mod __support {
17    pub use crate::__add_section_link_attribute as add_section_link_attribute;
18    pub use crate::__def_section_name as def_section_name;
19    pub use crate::__get_section as get_section;
20    pub use crate::__in_section_crate as in_section_crate;
21    pub use crate::__in_section_parse as in_section_parse;
22    pub use crate::__section_parse as section_parse;
23
24    #[cfg(feature = "proc_macro")]
25    pub use link_section_proc_macro::hash;
26    #[cfg(feature = "proc_macro")]
27    pub use link_section_proc_macro::ident_concat;
28
29    /// Declares the section_name macro.
30    #[macro_export]
31    #[doc(hidden)]
32    macro_rules! __def_section_name {
33        (
34            {$(
35                $__section:ident $__type:ident => $__prefix:tt __ $__suffix:tt;
36            )*}
37            AUXILIARY = $__aux_sep:literal;
38            MAX_LENGTH = $__max_length:literal;
39            HASH_LENGTH = $__hash_length:literal;
40            VALID_SECTION_CHARS = $__valid_section_chars:literal;
41        ) => {
42            /// Internal macro for generating a section name.
43            #[macro_export]
44            #[doc(hidden)]
45            macro_rules! __section_name {
46                $(
47                    (raw $__section $__type $name:ident) => {
48                        concat!(concat! $__prefix, stringify!($name), concat! $__suffix);
49                    };
50                    (raw $__section $__type $name:ident $aux:ident) => {
51                        concat!(concat! $__prefix, stringify!($name), $__aux_sep, stringify!($aux), concat! $__suffix);
52                    };
53                    ($pattern:tt $__section $__type $name:ident) => {
54                        $crate::__support::hash!($pattern ($__prefix) $name ($__suffix) $__hash_length $__max_length $__valid_section_chars);
55                    };
56                    ($pattern:tt $__section $__type $name:ident $aux:ident) => {
57                        $crate::__support::hash!($pattern ($__prefix) ($name $__aux_sep $aux) ($__suffix) $__hash_length $__max_length $__valid_section_chars);
58                    };
59                )*
60                ($pattern:tt $unknown_section:ident $unknown_type:ident $name:ident) => {
61                    const _: () = {
62                        compile_error!("Unknown section type: `{}`/`{}`", stringify!($unknown_section), stringify!($unknown_type));
63                    };
64                };
65            }
66        };
67    }
68
69    #[cfg(feature = "proc_macro")]
70    #[doc(hidden)]
71    #[macro_export]
72    macro_rules! __add_section_link_attribute(
73        ($section:ident $type:ident $name:ident $($aux:ident)? #[$attr:ident = __] $item:item) => {
74            $crate::__section_name!(
75                (#[$attr = __] #[allow(unsafe_code)] $item)
76                $section $type $name $($aux)?
77            );
78        }
79    );
80
81    #[cfg(not(feature = "proc_macro"))]
82    #[doc(hidden)]
83    #[macro_export]
84    macro_rules! __add_section_link_attribute(
85        ($section:ident $type:ident $name:ident #[$attr:ident = __] $item:item) => {
86            #[$attr = $crate::__section_name!(
87                raw $section $type $name
88            )] $item
89        }
90    );
91
92    // \x01: "do not mangle" (ref https://github.com/rust-lang/rust-bindgen/issues/2935)
93    #[cfg(target_vendor = "apple")]
94    def_section_name! {
95        {
96            data bare =>    ("__DATA,") __ ();
97            code bare =>    ("__TEXT,") __ ();
98            data section => ("__DATA,") __ (",regular,no_dead_strip");
99            code section => ("__TEXT,") __ (",regular,no_dead_strip");
100            data start =>   ("\x01section$start$__DATA$") __ ();
101            data end =>     ("\x01section$end$__DATA$") __ ();
102        }
103        AUXILIARY = "_";
104        MAX_LENGTH = 16;
105        HASH_LENGTH = 6;
106        VALID_SECTION_CHARS = "_ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
107    }
108
109    #[cfg(target_family = "wasm")]
110    def_section_name! {
111        {
112            data bare =>    (".data", ".link_section.") __ ();
113            data section => (".data", ".link_section.") __ ();
114            code bare =>    (".text", ".link_section.") __ ();
115            code section => (".text", ".link_section.") __ ();
116        }
117        AUXILIARY = ".";
118        MAX_LENGTH = 16;
119        HASH_LENGTH = 6;
120        VALID_SECTION_CHARS = "_ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
121    }
122
123    #[cfg(all(
124        not(target_vendor = "apple"),
125        not(target_vendor = "pc"),
126        not(target_family = "wasm")
127    ))]
128    def_section_name! {
129        {
130            data bare =>    ("_data", "_link_section_") __ ();
131            data section => ("_data", "_link_section_") __ ();
132            data start =>   ("__start_", "_data", "_link_section_") __ ();
133            data end =>     ("__stop_", "_data", "_link_section_") __ ();
134            code bare =>    ("_text", "_link_section_") __ ();
135            code section => ("_text", "_link_section_") __ ();
136            code start =>   ("__start_", "_text", "_link_section_") __ ();
137            code end =>     ("__stop_", "_text", "_link_section_") __ ();
138        }
139        AUXILIARY = "_";
140        MAX_LENGTH = 64;
141        HASH_LENGTH = 10;
142        VALID_SECTION_CHARS = "_ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
143    }
144
145    #[cfg(target_vendor = "pc")]
146    def_section_name! {
147        {
148            data bare =>    (".data", "$") __ ();
149            data section => (".data", "$") __ ("$b");
150            data start =>   (".data", "$") __ ("$a");
151            data end =>     (".data", "$") __ ("$c");
152            code bare =>    (".text", "$") __ ();
153            code section => (".text", "$") __ ("$b");
154            code start =>   (".text", "$") __ ("$a");
155            code end =>     (".text", "$") __ ("$c");
156        }
157        AUXILIARY = "$d$";
158        MAX_LENGTH = 64;
159        HASH_LENGTH = 10;
160        VALID_SECTION_CHARS = "_ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
161    }
162
163    #[cfg(not(feature = "proc_macro"))]
164    #[doc(hidden)]
165    #[macro_export]
166    macro_rules! __declare_macro {
167        ($vis:vis $ident:ident $generic_macro:ident $args:tt) => {
168            /// Internal macro for parsing the section. This is exported with
169            /// the same name as the type below.
170            #[doc(hidden)]
171            $vis use $crate::$generic_macro as $ident;
172        };
173    }
174
175    #[cfg(feature = "proc_macro")]
176    #[doc(hidden)]
177    #[macro_export]
178    macro_rules! __declare_macro {
179        ($vis:vis $ident:ident $generic_macro:ident $args:tt) => {
180            $crate::__support::ident_concat!(
181                (#[macro_export]
182                #[doc(hidden)]
183                macro_rules!)  (__ $ident __link_section_private_macro__) ({
184                    ($passthru:tt) => {
185                        $crate::$generic_macro!($passthru $args);
186                    };
187                })
188            );
189
190            $crate::__support::ident_concat!(
191                (#[doc(hidden)] pub use) (__ $ident __link_section_private_macro__) (as $ident;)
192            );
193        }
194    }
195
196    /// Define a link section.
197    #[macro_export]
198    #[doc(hidden)]
199    macro_rules! __section_parse {
200        // Has a generic (note that $generic eats the trailing semicolon)
201        (#[section $($args:tt)*] $(#[$meta:meta])* $vis:vis static $ident:ident : $(:: $path_prefix:ident ::)? $($path:ident)::* < $($generic:tt)*) => {
202            $crate::__section_parse!(@parsed #[section $($args)*] $(#[$meta])* $vis static $ident: ( $(:: $path_prefix ::)? $($path)::* < $($generic)*) ( $($generic)* ) __in_section_helper_macro_generic);
203        };
204        // No generic
205        (#[section $($args:tt)*] $(#[$meta:meta])* $vis:vis static $ident:ident : $(:: $path_prefix:ident ::)? $($path:ident)::* ;) => {
206            $crate::__section_parse!(@parsed #[section $($args)*] $(#[$meta])* $vis static $ident: ( $(:: $path_prefix ::)? $($path)::* ;) ( () > ; ) __in_section_helper_macro_no_generic);
207        };
208        // Both end up here...
209        (@parsed #[section $($args:tt)*] $(#[$meta:meta])* $vis:vis static $ident:ident : ($ty:ty ;) ( $generic_ty:ty > ; ) $generic_macro:ident) => {
210            $crate::__declare_macro!($vis $ident $generic_macro ($($args)*));
211            $crate::__section_parse!(@generate #[section $($args)*] $(#[$meta])* $vis static $ident: $ty, $generic_ty, $generic_macro);
212        };
213        (@generate #[section $($args:tt)*] $(#[$meta:meta])* $vis:vis static $ident:ident : $ty:ty, $generic_ty:ty, __in_section_helper_macro_generic) => {
214            $crate::__section_parse!(@generate #[section $($args)*] $(#[$meta])* $vis static $ident: $ty, $generic_ty, __base_case__);
215
216            impl ::core::iter::IntoIterator for $ident {
217                type Item = &'static $generic_ty;
218                type IntoIter = ::core::slice::Iter<'static, $generic_ty>;
219                fn into_iter(self) -> Self::IntoIter {
220                    $ident.as_slice().iter()
221                }
222            }
223        };
224        (@generate #[section $($args:tt)*] $(#[$meta:meta])* $vis:vis static $ident:ident : $ty:ty, $generic_ty:ty, $generic_macro:ident) => {
225            $(#[$meta])*
226            #[allow(non_camel_case_types)]
227            $vis struct $ident;
228
229            impl $crate::__support::SectionItemType for $ident {
230                type Item = $generic_ty;
231            }
232
233            impl ::core::fmt::Debug for $ident {
234                fn fmt(&self, f: &mut ::core::fmt::Formatter<'_>) -> ::core::fmt::Result {
235                    ::core::ops::Deref::deref(self).fmt(f)
236                }
237            }
238
239            impl ::core::ops::Deref for $ident {
240                type Target = $ty;
241                fn deref(&self) -> &Self::Target {
242                    self.const_deref()
243                }
244            }
245
246            $crate::__section_parse!(@deref #[section $($args)*] $(#[$meta])* $vis static $ident: $ty, $generic_ty, __base_case__);
247        };
248        (@deref #[section] $(#[$meta:meta])* $vis:vis static $ident:ident : $ty:ty, $generic_ty:ty, __base_case__) => {
249            impl $ident {
250                /// Get a `const` reference to the underlying section. In
251                /// non-const contexts, `deref` is sufficient.
252                pub const fn const_deref(&self) -> &$ty {
253                    static SECTION: $ty = {
254                        let section = $crate::__support::get_section!(name=$ident, type=$generic_ty, aux=);
255                        let name = $crate::__section_name!(
256                            raw data bare $ident
257                        );
258                        unsafe { <$ty>::new(name, section.0, section.1) }
259                    };
260                    &SECTION
261                }
262            }
263        };
264        (@deref #[section(aux=$aux:ident)] $(#[$meta:meta])* $vis:vis static $ident:ident : $ty:ty, $generic_ty:ty, __base_case__) => {
265            impl $ident {
266                /// Get a `const` reference to the underlying section. In
267                /// non-const contexts, `deref` is sufficient.
268                pub const fn const_deref(&self) -> &$ty {
269                    static SECTION: $ty = {
270                        let section = $crate::__support::get_section!(name=$ident, type=$generic_ty, aux=$aux);
271                        let name = $crate::__section_name!(
272                            raw data bare $aux $ident // swap
273                        );
274                        unsafe { <$ty>::new(name, section.0, section.1) }
275                    };
276                    &SECTION
277                }
278            }
279        };
280    }
281
282    #[cfg(miri)]
283    #[doc(hidden)]
284    #[macro_export]
285    macro_rules! __get_section {
286        (name=$ident:ident, type=$generic_ty:ty, aux=$($aux:ident)?) => {
287            // Disable link sections for miri (`extern static `␁section$start$__DATA$CTOR` is not supported by Miri`)
288            {
289                (std::ptr::null_mut(), std::ptr::null_mut())
290            }
291        };
292    }
293
294    #[cfg(all(not(miri), target_family = "wasm"))]
295    #[doc(hidden)]
296    #[macro_export]
297    macro_rules! __get_section {
298        (name=$ident:ident, type=$generic_ty:ty, aux=$($aux:ident)?) => {
299            {
300                static __START: ::core::sync::atomic::AtomicPtr::<::core::marker::PhantomData<$generic_ty>> = unsafe {
301                    ::core::sync::atomic::AtomicPtr::<::core::marker::PhantomData<$generic_ty>>::new(::core::ptr::null_mut())
302                };
303                static __END: ::core::sync::atomic::AtomicPtr::<::core::marker::PhantomData<$generic_ty>> = unsafe {
304                    ::core::sync::atomic::AtomicPtr::<::core::marker::PhantomData<$generic_ty>>::new(::core::ptr::null_mut())
305                };
306
307                $crate::__support::ident_concat!((#[no_mangle]pub extern "C" fn) (register_link_section_ $ident) ((data_ptr: *const u8, data_len: usize) {
308                    unsafe {
309                        __START.store(data_ptr as *mut ::core::marker::PhantomData<$generic_ty>, ::core::sync::atomic::Ordering::Relaxed);
310                        __END.store(data_ptr.add(data_len) as *mut ::core::marker::PhantomData<$generic_ty>, ::core::sync::atomic::Ordering::Relaxed);
311                    }
312                }));
313
314                (&__START, &__END)
315            }
316        }
317    }
318
319    #[cfg(all(not(miri), target_vendor = "pc"))]
320    #[doc(hidden)]
321    #[macro_export]
322    macro_rules! __get_section {
323        (name=$ident:ident, type=$generic_ty:ty, aux=$($aux:ident)?) => {
324            {
325                $crate::__support::add_section_link_attribute!(
326                    data start $ident $($aux)?
327                    #[link_section = __]
328                    static __START: [$generic_ty; 0] = [];
329                );
330                $crate::__support::add_section_link_attribute!(
331                    data end $ident $($aux)?
332                    #[link_section = __]
333                    static __END: [$generic_ty; 0] = [];
334                );
335
336                (
337                    unsafe { &raw const __START as $crate::__support::SectionPtr<$generic_ty> },
338                    unsafe { &raw const __END as $crate::__support::SectionPtr<$generic_ty> },
339                )
340            }
341        }
342    }
343
344    #[cfg(all(not(miri), not(target_family = "wasm"), not(target_vendor = "pc")))]
345    #[doc(hidden)]
346    #[macro_export]
347    macro_rules! __get_section {
348        (name=$ident:ident, type=$generic_ty:ty, aux=$($aux:ident)?) => {
349            {
350                extern "C" {
351                    $crate::__support::add_section_link_attribute!(
352                        data start $ident $($aux)?
353                        #[link_name = __]
354                        static __START: $crate::__support::SectionPtr<$generic_ty>;
355                    );
356                }
357                extern "C" {
358                    $crate::__support::add_section_link_attribute!(
359                        data end $ident $($aux)?
360                        #[link_name = __]
361                        static __END: $crate::__support::SectionPtr<$generic_ty>;
362                    );
363                }
364
365                (
366                    unsafe { &raw const __START as $crate::__support::SectionPtr<$generic_ty> },
367                    unsafe { &raw const __END as $crate::__support::SectionPtr<$generic_ty> },
368                )
369            }
370        }
371    }
372
373    /// Export a symbol into a link section.
374    #[macro_export]
375    #[doc(hidden)]
376    macro_rules! __in_section_parse {
377        // Needs to handle:
378        //  <name>
379        //  :: <name>
380        //  <path> :: <name>
381        //  :: <path> :: <name>
382        //  etc...
383        (#[in_section(unsafe, type = $stored_ty:ty, name = $ident:ident $( , aux = $aux:ident)?)] $($item:tt)*) => {
384            $crate::__support::in_section_crate!((type = $stored_ty), $ident, $($aux)?, $ident, ($($item)*));
385        };
386        (#[in_section(unsafe, name = $ident:ident $( , aux = $aux:ident)?)] $($item:tt)*) => {
387            $crate::__support::in_section_crate!(data, $ident, $($aux)?, $ident, ($($item)*));
388        };
389        (#[in_section( $($path:tt)* )] $($item:tt)*) => {
390            $crate::__support::in_section_parse!(path=[$($path)*] #[in_section($($path)*)] $($item)*);
391        };
392        (path=[$orig_path:path] #[in_section($name:ident)] $($item:tt)*) => {
393            $orig_path ! (
394                (v=0 (name=$name (path=[$orig_path] (item=($($item)*) ()))))
395            );
396        };
397        (path=[$orig_path:path] #[in_section(:: $($path:ident)::*)] $($item:tt)*) => {
398            $crate::__support::in_section_parse!(path=[$orig_path] #[in_section($($path)::*)] $($item)*);
399        };
400        (path=[$orig_path:path] #[in_section($prefix:ident :: $($path:ident)::*)] $($item:tt)*) => {
401            $crate::__support::in_section_parse!(path=[$orig_path] #[in_section($($path)::*)] $($item)*);
402        };
403    }
404
405    #[macro_export]
406    #[doc(hidden)]
407    macro_rules! __in_section_helper_macro_generic {
408        ((v=0 (name=$ident:ident (path=[$path:path] (item=$item:tt $rest:tt))))) => {
409            $crate::__support::in_section_crate!(section, $ident,, $path, $item);
410        };
411        ((v=0 (name=$ident:ident (path=[$path:path] (item=$item:tt $rest:tt)))) ((aux=$aux:ident)) )=> {
412            $crate::__support::in_section_crate!(section, $ident, $aux, $path, $item);
413        };
414        ((v=0 (name=$ident:ident (path=[$path:path] (item=$item:tt $rest:tt)))) () )=> {
415            $crate::__support::in_section_crate!(section, $ident,, $path, $item);
416        };
417        (v=$v:literal $rest:tt) => {
418            const _: () = {
419                compile_error!(concat!(
420                    "link-section: Unsupported version: `",
421                    stringify!($v),
422                    "`: ",
423                    stringify!($rest)
424                ));
425            };
426        };
427    }
428
429    #[macro_export]
430    #[doc(hidden)]
431    macro_rules! __in_section_helper_macro_no_generic {
432        ((v=0 (name=$ident:ident (path=[$path:path] (item=$item:tt $rest:tt))))) => {
433            $crate::__support::in_section_crate!(data, $ident,, $path, $item);
434        };
435        ((v=0 (name=$ident:ident (path=[$path:path] (item=$item:tt $rest:tt)))) ((aux=$aux:ident)) )=> {
436            $crate::__support::in_section_crate!(data, $ident, $aux, $path, $item);
437        };
438        ((v=0 (name=$ident:ident (path=[$path:path] (item=$item:tt $rest:tt)))) () )=> {
439            $crate::__support::in_section_crate!(data, $ident,, $path, $item);
440        };
441        (v=$v:literal $rest:tt) => {
442            const _: () = {
443                compile_error!(concat!(
444                    "link-section: Unsupported version: `",
445                    stringify!($v),
446                    "`: ",
447                    stringify!($rest)
448                ));
449            };
450        };
451    }
452
453    #[macro_export]
454    #[doc(hidden)]
455    #[allow(unknown_lints, edition_2024_expr_fragment_specifier)]
456    macro_rules! __in_section_crate {
457        (@type_select section $path:path, $item_ty:ty) => {
458            <$path as $crate::__support::SectionItemType>::Item
459        };
460        (@type_select data $path:path, $item_ty:ty) => {
461            $item_ty
462        };
463        (@type_select (type = $stored_ty:ty) $path:path, $item_ty:ty) => {
464            $stored_ty
465        };
466        ($type_source:tt, $ident:ident, $($aux:ident)?, $path:path, ($(#[$meta:meta])* $vis:vis fn $ident_fn:ident($($args:tt)*) $(-> $ret:ty)? $body:block)) => {
467            $crate::__add_section_link_attribute!(
468                data section $ident $($aux)?
469                #[link_section = __]
470                $(#[$meta])*
471                #[used]
472                #[allow(non_upper_case_globals)]
473                $vis static $ident_fn: $crate::__in_section_crate!(@type_select $type_source $path, fn($($args)*) $(-> $ret)?) =
474                    {
475                        $crate::__add_section_link_attribute!(
476                            code section $ident $($aux)?
477                            #[link_section = __]
478                            fn $ident_fn($($args)*) $(-> $ret)? $body
479                        );
480                        $ident_fn
481                    };
482            );
483        };
484        ($type_source:tt, $ident:ident, $($aux:ident)?, $path:path, ($(#[$meta:meta])* $vis:vis static _ : $ty:ty = $value:expr;)) => {
485            const _: () = {
486                $crate::__add_section_link_attribute!(
487                    data section $ident $($aux)?
488                    #[link_section = __]
489                    $(#[$meta])* #[used] $vis static ANONYMOUS: $crate::__in_section_crate!(@type_select $type_source $path, $ty) = $value;
490                );
491            };
492        };
493        ($type_source:tt, $ident:ident, $($aux:ident)?, $path:path, ($(#[$meta:meta])* $vis:vis static $ident_static:ident : $ty:ty = $value:expr;)) => {
494            $crate::__add_section_link_attribute!(
495                data section $ident $($aux)?
496                #[link_section = __]
497                $(#[$meta])* #[used] $vis static $ident_static: $crate::__in_section_crate!(@type_select $type_source $path, $ty) = $value;
498            );
499        };
500        (data, $ident:ident, $($aux:ident)?, $path:path, ($(#[$meta:meta])* $item:item)) => {
501            $crate::__add_section_link_attribute!(
502                data section $ident $($aux)?
503                #[link_section = __]
504                $(#[$meta])* #[used] $item
505            );
506        };
507    }
508
509    pub trait SectionItemType {
510        type Item;
511    }
512
513    impl<T> SectionItemType for super::TypedSection<T> {
514        type Item = T;
515    }
516
517    /// On Apple platforms, the linker provides a pointer to the start and end
518    /// of the section regardless of the section's name.
519    #[cfg(all(not(target_vendor = "pc"), not(target_family = "wasm")))]
520    pub type SectionPtr<T> = *const ::core::marker::PhantomData<T>;
521    /// On LLVM/GCC/MSVC platforms, we cannot use start/end symbols for sections
522    /// without C-compatible names, so instead we drop a [T; 0] at the start and
523    /// end of the section.
524    #[cfg(target_vendor = "pc")]
525    pub type SectionPtr<T> = *const [T; 0];
526    /// On WASM, we use an atomic pointer to the start and end of the section.
527    #[cfg(target_family = "wasm")]
528    pub type SectionPtr<T> =
529        &'static ::core::sync::atomic::AtomicPtr<::core::marker::PhantomData<T>>;
530}
531
532/// Define a link section.
533///
534/// # Example
535/// ```rust
536/// use link_section::{in_section, section};
537///
538/// #[section]
539/// pub static DATA_SECTION: link_section::Section;
540///
541/// #[in_section(DATA_SECTION)]
542/// pub fn data_function() {
543///     println!("data_function");
544/// }
545/// ```
546#[cfg(feature = "proc_macro")]
547pub use ::link_section_proc_macro::section;
548
549/// Place an item into a link section.
550///
551/// # Functions and typed sections
552///
553/// As a special case, since function declarations by themselves are not sized,
554/// functions in typed sections are split and stored as function pointers.
555#[cfg(feature = "proc_macro")]
556pub use ::link_section_proc_macro::in_section;
557
558/// An untyped link section that can be used to store any type. The underlying
559/// data is not enumerable.
560#[repr(C)]
561pub struct Section {
562    name: &'static str,
563    start: __support::SectionPtr<()>,
564    end: __support::SectionPtr<()>,
565}
566
567impl Section {
568    #[doc(hidden)]
569    pub const unsafe fn new(
570        name: &'static str,
571        start: __support::SectionPtr<()>,
572        end: __support::SectionPtr<()>,
573    ) -> Self {
574        Self { name, start, end }
575    }
576}
577
578#[cfg(target_family = "wasm")]
579impl Section {
580    /// The start address of the section.
581    pub fn start_ptr(&self) -> *const () {
582        let ptr = self.start.load(::core::sync::atomic::Ordering::Relaxed) as *const ();
583        if ptr.is_null() {
584            panic!(
585                "Section {} was not initialized by the host environment",
586                self.name
587            );
588        }
589        ptr
590    }
591    /// The end address of the section.
592    pub fn end_ptr(&self) -> *const () {
593        let ptr = self.end.load(::core::sync::atomic::Ordering::Relaxed) as *const ();
594        if ptr.is_null() {
595            panic!(
596                "Section {} was not initialized by the host environment",
597                self.name
598            );
599        }
600        ptr
601    }
602    /// The byte length of the section.
603    pub fn byte_len(&self) -> usize {
604        unsafe { (self.end_ptr() as *const u8).offset_from(self.start_ptr() as *const u8) as usize }
605    }
606}
607
608#[cfg(not(target_family = "wasm"))]
609impl Section {
610    /// The start address of the section.
611    pub const fn start_ptr(&self) -> *const () {
612        self.start as *const ()
613    }
614    /// The end address of the section.
615    pub const fn end_ptr(&self) -> *const () {
616        self.end as *const ()
617    }
618    /// The byte length of the section.
619    pub const fn byte_len(&self) -> usize {
620        unsafe { (self.end_ptr() as *const u8).offset_from(self.start_ptr() as *const u8) as usize }
621    }
622}
623
624impl ::core::fmt::Debug for Section {
625    fn fmt(&self, f: &mut ::core::fmt::Formatter<'_>) -> ::core::fmt::Result {
626        f.debug_struct("Section")
627            .field("name", &self.name)
628            .field("start", &self.start_ptr())
629            .field("end", &self.end_ptr())
630            .field("byte_len", &self.byte_len())
631            .finish()
632    }
633}
634
635unsafe impl Sync for Section {}
636unsafe impl Send for Section {}
637
638/// A typed link section that can be used to store any sized type. The
639/// underlying data is enumerable.
640#[repr(C)]
641pub struct TypedSection<T: 'static> {
642    name: &'static str,
643    start: __support::SectionPtr<T>,
644    end: __support::SectionPtr<T>,
645    _phantom: ::core::marker::PhantomData<T>,
646}
647
648#[cfg(target_family = "wasm")]
649impl<T: 'static> TypedSection<T> {
650    /// The start address of the section.
651    pub fn start_ptr(&self) -> *const T {
652        let ptr = self.start.load(::core::sync::atomic::Ordering::Relaxed) as *const T;
653        if ptr.is_null() {
654            panic!(
655                "TypedSection {} was not initialized by the host environment",
656                self.name
657            );
658        }
659        ptr
660    }
661
662    /// The end address of the section.
663    pub fn end_ptr(&self) -> *const T {
664        let ptr = self.end.load(::core::sync::atomic::Ordering::Relaxed) as *const T;
665        if ptr.is_null() {
666            panic!(
667                "TypedSection {} was not initialized by the host environment",
668                self.name
669            );
670        }
671        ptr
672    }
673
674    /// The byte length of the section.
675    pub fn byte_len(&self) -> usize {
676        unsafe { (self.end_ptr() as *const u8).offset_from(self.start_ptr() as *const u8) as usize }
677    }
678
679    /// The number of elements in the section.
680    pub fn len(&self) -> usize {
681        self.byte_len() / self.stride()
682    }
683
684    /// True if the section is empty.
685    pub fn is_empty(&self) -> bool {
686        self.len() == 0
687    }
688
689    /// The section as a slice.
690    pub fn as_slice(&self) -> &[T] {
691        if self.is_empty() {
692            &[]
693        } else {
694            unsafe { ::core::slice::from_raw_parts(self.start_ptr(), self.len()) }
695        }
696    }
697}
698
699#[cfg(not(target_family = "wasm"))]
700impl<T: 'static> TypedSection<T> {
701    /// The start address of the section.
702    pub const fn start_ptr(&self) -> *const T {
703        self.start as *const T
704    }
705
706    /// The end address of the section.
707    pub const fn end_ptr(&self) -> *const T {
708        self.end as *const T
709    }
710
711    /// The byte length of the section.
712    pub const fn byte_len(&self) -> usize {
713        unsafe { (self.end_ptr() as *const u8).offset_from(self.start_ptr() as *const u8) as usize }
714    }
715
716    /// The number of elements in the section.
717    pub const fn len(&self) -> usize {
718        self.byte_len() / self.stride()
719    }
720
721    /// True if the section is empty.
722    pub const fn is_empty(&self) -> bool {
723        self.len() == 0
724    }
725
726    /// The section as a slice.
727    pub const fn as_slice(&self) -> &[T] {
728        if self.is_empty() {
729            &[]
730        } else {
731            unsafe { ::core::slice::from_raw_parts(self.start_ptr(), self.len()) }
732        }
733    }
734}
735
736// Non-const, shared functions (or functions that don't depend on the pointers)
737impl<T: 'static> TypedSection<T> {
738    #[doc(hidden)]
739    pub const unsafe fn new(
740        name: &'static str,
741        start: __support::SectionPtr<T>,
742        end: __support::SectionPtr<T>,
743    ) -> Self {
744        Self {
745            name,
746            start,
747            end,
748            _phantom: ::core::marker::PhantomData,
749        }
750    }
751
752    /// The stride of the typed section.
753    pub const fn stride(&self) -> usize {
754        assert!(
755            ::core::mem::size_of::<T>() > 0
756                && ::core::mem::size_of::<T>() * 2 == ::core::mem::size_of::<[T; 2]>()
757        );
758        ::core::mem::size_of::<T>()
759    }
760
761    /// The offset of the item in the section, if it is in the section.
762    pub fn offset_of(&self, item: &T) -> Option<usize> {
763        let ptr = item as *const T;
764        if ptr < self.start_ptr() || ptr >= self.end_ptr() {
765            None
766        } else {
767            Some(unsafe { ptr.offset_from(self.start_ptr()) as usize })
768        }
769    }
770
771    /// The section as a mutable slice.
772    ///
773    /// # Safety
774    ///
775    /// This cannot be safely used and is _absolutely unsound_ if any other
776    /// slices are live.
777    #[allow(clippy::mut_from_ref)]
778    pub unsafe fn as_mut_slice(&self) -> &mut [T] {
779        if self.is_empty() {
780            &mut []
781        } else {
782            unsafe { ::core::slice::from_raw_parts_mut(self.start_ptr() as *mut T, self.len()) }
783        }
784    }
785}
786
787impl<'a, T> ::core::iter::IntoIterator for &'a TypedSection<T> {
788    type Item = &'a T;
789    type IntoIter = ::core::slice::Iter<'a, T>;
790    fn into_iter(self) -> Self::IntoIter {
791        self.as_slice().iter()
792    }
793}
794
795impl<T> ::core::ops::Deref for TypedSection<T> {
796    type Target = [T];
797    fn deref(&self) -> &Self::Target {
798        self.as_slice()
799    }
800}
801
802impl<T> ::core::fmt::Debug for TypedSection<T> {
803    fn fmt(&self, f: &mut ::core::fmt::Formatter<'_>) -> ::core::fmt::Result {
804        f.debug_struct("TypedSection")
805            .field("name", &self.name)
806            .field("start", &self.start_ptr())
807            .field("end", &self.end_ptr())
808            .field("len", &self.len())
809            .field("stride", &self.stride())
810            .finish()
811    }
812}
813
814unsafe impl<T> Sync for TypedSection<T> where T: Sync {}
815unsafe impl<T> Send for TypedSection<T> where T: Send {}
link_section/lib.rs

link_section/
lib.rs
