Add dynamic loading support #1846

joechrisellis · 2020-07-27T12:52:27Z

Hi guys,

Following on from issue 1541, here's an implementation for libloading support in bindgen. I'd still consider this a prototype at the minute, so any comments are welcome and appreciated.

Implementation

The existing functionality is maintained if dynamic loading mode is not specified.
We introduce two new flags -- --dynamic-loading and --dynamic-library-name -- which enable dynamic loading mode and specify a name for the shared library respectively. The 'name' of the shared library is what you want the struct containing the bindings to be called. For example, you could call it BZip2 -- then you'd instantiate the dynamically loaded library with let lib = BZip2::new();. If --dynamic-library-name is not specified it'll just default to Lib.
If dynamic loading mode is specified, the bindings are created inside a library struct alongside some libloading boilerplate.

Example

Given the following header.h:

int foo(int x);
void bar(double x);

And the following code inside our build.rs:

let bindings = bindgen::Builder::default()
    .header("header.h")
    // Use dynamic loading
    .dynamic_loading(true)
    .dynamic_library_name("MyLibrary")
    // ...
    .generate()
    .expect("Unable to generate bindings");

We generate the following bindings:

/* automatically generated by rust-bindgen 0.54.1 */

pub struct MyLibrary<'a> {
    foo: libloading::Symbol<
        'a,
        unsafe extern "C" fn(x: ::std::os::raw::c_int) -> ::std::os::raw::c_int,
    >,
    bar: libloading::Symbol<'a, unsafe extern "C" fn(x: f64)>,
}
impl<'a> MyLibrary<'a> {
    pub fn new(lib: &libloading::Library) -> MyLibrary {
        unsafe {
            MyLibrary {
                foo: lib.get("foo".as_bytes()).unwrap(),
                bar: lib.get("bar".as_bytes()).unwrap(),
            }
        }
    }
}

Which we can then use in our code with the following:

#![allow(non_upper_case_globals)]
#![allow(non_camel_case_types)]
#![allow(non_snake_case)]
include!(concat!(env!("OUT_DIR"), "/bindings.rs"));

extern crate libloading;

pub fn main() {
    let lib = libloading::Library::new("/path/to/shared/lib.so").unwrap();
    let library_wrapper = MyLibrary::new(&lib);
    unsafe { (library_wrapper.bar)(123.0) };
}

Multiple Dynamically Loaded Libraries

If you want to use multiple dynamically loaded libraries, the correct approach would be to do this in your build.rs:

let bindings_x = bindgen::Builder::default()
    .header("header_x.h")
    // Use dynamic loading
    .dynamic_loading(true)
    .dynamic_library_name("LibraryX")
    // ...
    .generate()
    .expect("Unable to generate bindings");

let bindings_y = bindgen::Builder::default()
    .header("header_y.h")
    // Use dynamic loading
    .dynamic_loading(true)
    .dynamic_library_name("LibraryY")
    // ...
    .generate()
    .expect("Unable to generate bindings");

let out_path = PathBuf::from(env::var("OUT_DIR").unwrap());
lib1_bindings
    .write_to_file(out_path.join("libx_bindings.rs"))
    .expect("Couldn't write bindings!");
lib2_bindings
    .write_to_file(out_path.join("liby_bindings.rs"))
    .expect("Couldn't write bindings!");

Then do the following in your code:

extern crate libloading;

mod libx {
    include!(concat!(env!("OUT_DIR"), "/libx_bindings.rs"));
}
mod liby {
    include!(concat!(env!("OUT_DIR"), "/liby_bindings.rs"));
}
pub use lib1::LibraryX;
pub use lib2::LibraryY;

(the mod libx { ... } is to prevent namespace collisions if LibraryX and LibraryY have common includes -- e.g. if they both have #include <stdint.h>)

Comments and criticisms absolutely welcome! If this seems like a suitable approach I can update the docs in a separate PR. Cheers! 🍻

dergroncki · 2020-08-02T15:46:28Z

I tested the dynamic loading support with one dll file on windows and it worked like a charm! Exactly what I wanted.

Question: Instead of "MyLibrary" as in your example I used "ModelLib", but "ModelLib" is marked as unknown although the program is compiled without errors. Thanks for any hint.

Program extract of the automatically generated code:

extern crate libloading;
pub struct ModelLib<'a> {
    #[doc = ""]
    createInstance: libloading::Symbol<
        'a,
        unsafe extern "C" fn(lengthBillet_m: f64, radiusBillet_m: f64) -> *mut ModelData,
    >,
    destroyInstance:
        libloading::Symbol<'a, unsafe extern "C" fn(data: *mut ModelData) -> ::std::os::raw::c_int>,
    calculate:
        libloading::Symbol<'a, unsafe extern "C" fn(data: *mut ModelData) -> ::std::os::raw::c_int>,
    enableLogging: libloading::Symbol<
        'a,
        unsafe extern "C" fn(
            data: *mut ModelData,
            path: *const ::std::os::raw::c_char,
        ) -> ::std::os::raw::c_int,
    >,
    errorLog: libloading::Symbol<
        'a,
        unsafe extern "C" fn(msg: *mut ::std::os::raw::c_char, maxSize: ::std::os::raw::c_int),
    >,
    errorLogSize: libloading::Symbol<'a, unsafe extern "C" fn() -> ::std::os::raw::c_int>,
    customer: libloading::Symbol<
        'a,
        unsafe extern "C" fn(msg: *mut ::std::os::raw::c_char, maxSize: ::std::os::raw::c_int),
    >,
    date: libloading::Symbol<
        'a,
        unsafe extern "C" fn(msg: *mut ::std::os::raw::c_char, maxSize: ::std::os::raw::c_int),
    >,
    version: libloading::Symbol<
        'a,
        unsafe extern "C" fn(msg: *mut ::std::os::raw::c_char, maxSize: ::std::os::raw::c_int),
    >,
}
impl<'a> ModelLib<'a> {
    pub fn new(lib: &libloading::Library) -> ModelLib {
        unsafe {
            ModelLib {
                createInstance: lib.get("createInstance".as_bytes()).unwrap(),
                destroyInstance: lib.get("destroyInstance".as_bytes()).unwrap(),
                calculate: lib.get("calculate".as_bytes()).unwrap(),
                enableLogging: lib.get("enableLogging".as_bytes()).unwrap(),
                errorLog: lib.get("errorLog".as_bytes()).unwrap(),
                errorLogSize: lib.get("errorLogSize".as_bytes()).unwrap(),
                customer: lib.get("customer".as_bytes()).unwrap(),
                date: lib.get("date".as_bytes()).unwrap(),
                version: lib.get("version".as_bytes()).unwrap(),
            }
        }
    }
}

joechrisellis · 2020-08-03T08:20:18Z

@dergroncki, good to know that it worked for you! If the program compiles just fine, then the 'not found' error you're seeing is probably because your IDE is unable to process the include macros for whatever reason. You could test this by copying the generated bindings.rs file and dumping it into your file in the place of the include macro -- if this doesn't show any errors, then it's probably that.

On another, rather more general note -- I'm planning on spending some time today to get this PR into a production-ready state. At the moment, it's all rather ad-hoc and will occasionally generate invalid bindings for C++ headers. Happy to see that you have found it useful though. 😄

hug-dev

Looks good 😃 A few comments/questions

hug-dev · 2020-08-06T13:44:13Z

src/lib.rs

+    dynamic_loading: bool,
+
+    /// The name of the dynamic library if we are generating bindings for a shared library.
+    dynamic_library_name: Option<String>,


Would it be possible to merge those two options in the commands and the builder? As in have a dynamic_loading argument taking a name value? Or something similar. That way it would be easier to use and implement maybe 😃 If the value is optional that would be even better to default to the library name in that case. Otherwise we can check if the name string is empty or not.

Yes, that's a much better idea. I'll do this 😄

hug-dev · 2020-08-06T13:51:23Z

src/ir/context.rs

+                // Finally, only generate dynamic bindings for functions (for now! this could
+                // change in the future to support variables).


Interesting, I had not considered dynamically loading variables.

Yeah, AFAIK static constants should be dynamically-loadable too, but I haven't thought about this too much. 👍

goto-bus-stop · 2020-08-08T09:14:11Z

This looks nice! I'm trying to use it with a two-crate setup, one -sys and one Rusty wrapper. Unfortunately that doesn't work right now because the struct members are private. Should they just all be declared pub by default? I think that would match the non-dynamic bindgen behaviour.

joechrisellis · 2020-08-11T10:24:21Z

This looks nice! I'm trying to use it with a two-crate setup, one -sys and one Rusty wrapper. Unfortunately that doesn't work right now because the struct members are private. Should they just all be declared pub by default? I think that would match the non-dynamic bindgen behaviour.

Yes, you're absolutely right, they should be. This is a trivial fix, will update in just a moment. My bad! 🙂

nagisa · 2020-08-23T14:59:04Z

Hi,

Maintainer of libloading here. This is all super cool. I do have a suggestion in terms of what the generated API should look like. I suggest that instead of generating a structure with public fields you may want to expose the symbols through methods on an inherent implementation instead:

struct SomeName<'a> {
    sym1: Symbol<...>,
    sym2: Symbol<...>,
}

impl SomeName<'a> {
    unsafe extern "C" fn sym1(&self, ...) { /* call self.sym1 */ }
    unsafe extern "C" fn sym2(&self, ...) { /* call self.sym2 */ }
}

Doing it this way is somewhat safer, and more future proof as breaking changes to libloading or bindgen most likely would have no effect on the API most people would use.

Another thing that needs to be triple-checked are the globals (i.e. what conventionally translates to extern "C" { static FOO: ...; }).

joechrisellis · 2020-08-25T10:44:32Z

@nagisa thanks for your excellent suggestions! I will update the patch accordingly. 😄

joechrisellis · 2020-08-25T11:49:32Z

@Michael-F-Bryan would it be okay to adapt some of your ideas for this patch? Specifically, we're interested in doing what @nagisa has suggested above, which is very similar to your work. Just wanted to check with you! 😄

timfish · 2020-08-25T20:34:52Z

Many thanks for all the work that's going into getting dynamic support. I've already had to write loads of dynamic bindings manually and it's painful.

@joechrisellis if you're passing the library name to .dynamic_library_name("LibraryY") in build.rs, could you make the path in load_from_path an Option and default to that name is no path is supplied? This would allow users to load from a specific path or pass None to use the OS's default resolution.

So modifying the work from @Michael-F-Bryan :

impl Bindings {
    pub unsafe fn load_from_path<P>(
        path: Option<P>,
    ) -> Result<Self, ::libloading::Error>
    where
        P: AsRef<::std::ffi::OsStr>,
    {
        let path = path.unwrap_or("LibraryY"); // something like this...
        let library = ::libloading::Library::new(path)?;
        ...
    }
}

My dream would be that when I'm creating a *-sys crate, consumers of the crate could switch between dynamic and static with only a feature flag. This would require that both are exposed though the same code paths.

So for dynamic you'd get:

struct SomeName<'a> {
    sym1: Symbol<...>,
    sym2: Symbol<...>,
}

impl SomeName<'a> {
    unsafe extern "C" fn sym1(&self, ...) { /* call self.sym1 */ }
    unsafe extern "C" fn sym2(&self, ...) { /* call self.sym2 */ }
}

and for static you'd get:

struct SomeName;

impl SomeName<'a> {
    unsafe extern "C" fn sym1(&self, ...) { /* call static bindings */ }
    unsafe extern "C" fn sym2(&self, ...) { /* call static bindings */ }
}

Without this, the Rust wrappers for sys crates are going to need some laborious boilerplate abstraction over the top to support both dynamic and static bindings.

I'm not suggesting we modify the default bindgen behaviour, but it would be nice to support this kind of usage.

joechrisellis · 2020-08-26T11:34:32Z

Hi @timfish!

@joechrisellis if you're passing the library name to .dynamic_library_name("LibraryY") in build.rs, could you make the path in load_from_path an Option and default to that name is no path is supplied? This would allow users to load from a specific path or pass None to use the OS's default resolution.

I am a little skeptical of overloading the .dynamic_library_name method -- at the moment, that sets the name of the struct for the generated bindings. The purpose of this is so that we can avoid name collisions if we want to include multiple dynamically-loaded libraries in a single project. This is explained a bit more in the original issue (issue 1541), but I think some of the information there might be slightly outdated now. Unless there is some mechanism/env var like LD_LIBRARY_PATH that can resolve the name of the library (i.e. LibraryY) to a path at runtime that I am unaware of? Let me know if there is! 😄

However, I do like the idea of perhaps passing a path at build-time in build.rs. Something like .dynamic_library_path would work quite well. So, we could do exactly what you suggest, but introduce a new option for it instead of overloading an existing one. Let me know if you think this is the way to go.

My dream would be that when I'm creating a *-sys crate, consumers of the crate could switch between dynamic and static with only a feature flag. This would require that both are exposed though the same code paths.

This is a great idea, although I do think it's probably out-of-scope for this ticket. There might also be some further challenges with doing this. I think that'd work fine for C bindings, but for C++ bindings where we generate structs for classes, we would probably have to find some workaround.

Appreciate your comments, too! Glad to see that people are finding this useful.

Michael-F-Bryan · 2020-08-26T16:21:27Z

@Michael-F-Bryan would it be okay to adapt some of your ideas for this patch? Specifically, we're interested in doing what @nagisa has suggested above, which is very similar to your work. Just wanted to check with you! smile

Yeah, for sure! The best thing that could happen is someone reuses ideas/code from my prototype and integrates them upstream 🙂

hug-dev · 2020-08-27T11:57:52Z

One thing I thought about: some dynamic libraries do not implement all of the functions of their corresponding API (I saw this for the PKCS 11 Crypto API for example).
That means that a call to new would error out if one of the function is not implemented.
If you think this is a problem as well, I can propose the following solution: the Library struct could contain Option of function pointers instead of them directly and the new method would set the corresponding one to None if the get call errors out.
What do you think?

hug-dev · 2020-09-14T11:42:25Z

You have to:

let some_fn_ptr = some_struct.some_fn_ptr;
some_fn_ptr(arg);

Would it be because more parenthesis are needed 😋? As in: (some_struct.some_fn_ptr)(arg). I can see that @joechrisellis has them in the methods but not sure if they are needed there.

In any case, if making fields public is not a problem we could have both things:

being able to directly access the fields
having the methods to make it easier

I would prefer returning a Result as there would be loss of error information during the conversion Err(libloading::Error) -> None. Callers that want to disrecard this could call .ok() on the Result?

timfish · 2020-09-14T12:39:18Z

Would it be because more parenthesis are needed 😋?

Probably! 🤦‍♂️ 🤣

But yes, my point was that the methods make the interface a bit simpler to consume!

Michael-F-Bryan · 2020-09-14T12:53:20Z

Besides ergonomics, exposing the bindings as methods is required for safety. If the fields were public, it'd be too easy for people to extract the underlying function pointer and accidentally use it after the library is unloaded from memory. That's one of the big reasons libloading uses its own Symbol wrapper.

See nagisa/rust_libloading#13 (comment) from the libloading repo and the linked rust-lang/rust#29625 (comment).

hug-dev · 2020-09-14T14:30:27Z

Agree that having Symbol seems safer. So one option would be to have only public fields of type Result<Symbol<..>> and the methods to access the functions easily and that also return a Result.

I think also that what proposed @goto-bus-stop might be a good idea:

I don't know what a good solution would be though—adding a method to check for symbol existence might be too much auto-generated API surface for bindgen, and you'd have to deal with the possibility of loaded symbol names clashing with the bindgen-provided method names…

For each function toto there could be two associated methods on the TestLib struct:

fn can_call_toto(&self) -> Result<(), libloading::Error>: returning basically self.toto.map(|_| ())
fn toto: expected prototype but without returning a Result, directly return the contained value or panic if there was an error when calling get

Then the assumption for callers would be to do something like:

can_call_toto()?;
toto();

Or directly call toto if you are sure!

the possibility of loaded symbol names clashing with the bindgen-provided method names…

Maybe we could address that by having the implementation of the can_call methods inside their own namespace. I believe you can have impl blocks inside submodules. Could even be the can_call module, with the same name as the function:

can_call::toto()?;
toto();

edit: hmm forgot that those are methods on a struct so the namespacing trick will probably not work 🤦

Michael-F-Bryan · 2020-09-15T02:33:57Z

Agree that having Symbol seems safer.

@hug-dev, keep in mind that libloading::Symbol holds a reference to the original library to prevent accidentally using it after the library is unloaded without runtime overhead. Storing a Symbol in your wrapper struct alongside the libloading::Library would create a self-referential type.

That's why the wrapper's constructor (as currently formulated) would dereference a Symbol to get at the function pointer directly, and store that in the generated type.

Safety is maintained by hiding function pointers behind a method call and making sure the wrapper retains ownership of the Library, making sure functions and pointers to static variables can't outlive the library they came from.

So one option would be to have only public fields of type Result<Symbol<..>> and the methods to access the functions easily and that also return a Result.

You can't make the fields public.

If they are public, it's possible to use the fact that Symbol implements Deref<Target=fn(...)> and that function pointers are Copy to use a function pointer after the library it points into is removed from memory.

For each function toto there could be two associated methods on the TestLib struct:

fn can_call_toto(&self) -> Result<(), libloading::Error>: returning basically self.toto.map(|_| ())

fn toto: expected prototype but without returning a Result, directly return the contained value or panic if there was an error when calling get

This approach seems to be the most ergonomic. That way you can look-before-you-leap if you know a symbol will always be present, but also perform the check if you need to. I'm guessing the unwrap() call won't add enough overhead to be noticeable considering you are already doing dynamic dispatch with the function call.

To help with namespacing, what about adding a helper struct so you can write my_bindings.can_call().toto()? So the can_call() method returns a helper type that borrows the bindings and has methods with the equivalent of can_call_toto().

In the unlikely event that a library has a can_call symbol, you could keep prepending/appending underscores until there are no ambiguities.

joechrisellis · 2020-09-15T08:35:42Z

@Michael-F-Bryan has made some excellent points above. I also like @hug-dev's idea of implementing a can_call/look-before-you-leap method. Doing this via a helper struct seems like the right approach.

Thinking about the (probably) more common case where all of the symbols in the dynamic library are guaranteed to be defined, I also think it would be useful to have an option that allows us to fail early if a libloading::Error is raised inside the new method for our dynamic loading library type. This way, we can avoid panicking at runtime if something goes wrong early on when we're trying to load the library. I think that this should be the default option; I would guess that most people aren't working with modular/partially-defined libraries, and in that case, they can deal with an interface that is more ergonomical. I was thinking perhaps --fail-early/fail_early, set to true by default, and with some disclaimer that it's possible to get panics if you choose to turn this off? Would love to hear your thoughts on this. 😄

hug-dev · 2020-09-15T09:05:23Z

Thanks for the explanation, your points make sense and give arguments in favor of having extra helper methods to check the Result only.

I like the idea of the helper struct containing all the can_call_... methods!

I like the idea of the --fail-early option which will also make code generation simpler: the TestLib struct can then directly contain the function pointers and it is no longer need to have the helper struct with the can_call methods. Or they should still be there but always return Ok(()) so that the interface generated does not change with/without the option.

I would agree of adding this option but not sure of what should be the default. If the default is failing late, then a --fail-early option makes sense but if failing early is the default then probably a --fail-late option would be better 😃

joechrisellis · 2020-10-01T08:02:18Z

@emilio hello! I think this is ready for review now -- I think we can add the --fail-early flag in a future PR if you think it's worthwhile. 😄

emilio · 2020-10-06T23:52:37Z

(sorry for the lag here, I've been a bit too busy lately :/)

I'll try to get to this this week. Thanks for the patience!

DominicD · 2020-10-26T10:09:41Z

Hi I am using this (great work btw! 👍 ) and it does work however I have 2 questions/problems.

In the example in the beginning the function dynamic_loading() is called. It seems to me there was some change because in my case it does not exist and it works without calling it.
The bindings are created every time I build. I am not sure if this is related to this pull request or if it is a general bindgen thing? Is there anything I can do to change that?

joechrisellis · 2020-10-26T16:15:26Z

@DominicD thanks for the feedback! To answer your questions:

Things have evolved slightly since this patch was first submitted. The .dynamic_loading({true,false}) builder method has been superseded by .dynamic_library_name("..."). If you specify this option, it'll generate code for dynamic loading. If you don't, it'll run bindgen for your usual static bindings. Thanks for pointing this out though -- it is a good thing to point out for others!
I believe this is a general bindgen thing. FWIW I have heard of some people generating the bindings once (for each platform they need) using bindgen from the CLI. This might be a good choice for you. It has the advantage of quicker build times, (a) bindgen won't need to be run and (b) you won't have to pull in bindgen and its dependencies for a clean build.

emilio

Finally got some time to go through this. Really sorry again for the lag.

I think I might be missing something about why you chose this approach rather than something simpler hanging off the existing code generation machinery? Off-hand it seems this patch just takes a whole separate code generation step, while it could (I think) be part of the current machinery quite easily, unless I'm missing something.

emilio · 2020-10-27T10:46:43Z

src/ir/context.rs

+            .filter(|&(_, item)| {
+                // If the user has not chosen to do dynamic loading, then we have nothing to
+                // do.
+                if !self.options().dynamic_loading {


Seems like this check should really go at the beginning of the function rather than being done for every item.

Quite right -- will fix.

emilio · 2020-10-27T10:47:49Z

src/ir/context.rs

+                // If there is a whitelist and this function is not on it, don't add it.
+                if !self.options().whitelisted_functions.is_empty() &&
+                    !self.options().whitelisted_functions.matches(&name)
+                {


I would expect this to be accounted for via the regular whitelisting mechanism, why is this needed?

Yep, I think this can be simplified. I think I had the wrong idea of the relationship between items, codegen_items, and whitelisted_items. I've changed this to iterate through self.items(), but filter out anything whose item ID is not inside codegen_items. It seems to do the job -- is that what you had in mind?

emilio · 2020-10-27T10:47:54Z

src/ir/context.rs

+                // If there is a blacklist and this function is on it, don't add it.
+                if !self.options().blacklisted_functions.is_empty() &&
+                    self.options.blacklisted_functions.matches(&name)
+                {


Same about this.

emilio · 2020-10-27T10:48:36Z

src/ir/context.rs

+
+                // We don't want to include the root module in the list of items to generate
+                // dynamic bindings for.
+                if item.id() == self.root_module {


We're only generating functions so this check is redundant, right?

Yep, great spot.

emilio · 2020-10-27T10:55:31Z

src/lib.rs

+        mut self,
+        dynamic_library_name: T,
+    ) -> Self {
+        self.options.dynamic_loading = true;


Do you really need to keep track of self.options.dynamic_loading? It seems you really just need a library name, so the dynamic_loading checks could just be self.options.dynamic_library_name.is_some().

Fixed this.

emilio · 2020-10-27T10:56:46Z

src/codegen/mod.rs

@@ -3948,11 +3959,45 @@ pub(crate) fn codegen(
            &(),
        );

+        // If the set of items to generate dynamic bindings for is nonempty...
+        if !context.dyngen_items().is_empty() {


So basically... This is just effectively generating all the functions right now, is that right?

The way I'd have approached this would be something like, maybe:

Add an extra field to CodegenResult (dynamic_functions? / whatever)

Handle this in CodeGenerator for Function (just something like if ctx.options().dynamic_loading { /* generate appropriate things */ }, and instead of pushing to the regular CodegenResult field, push it to the dynamic functions, which you'd then handle here.

Is there any reason such an approach wouldn't work? It'd handle a lot more edge cases than this (template functions, etc, which this patch doesn't handle), and should also be much simpler / not need extra ItemSets.

Co-authored-by: Michael-F-Bryan <[email protected]>

emilio

Sorry for the lag, didn't notice this was updated :(. Feel free to ping next time as needed, I get way too much github mail...

This looks basically good to me, thank you! I have some relatively minor nits, but I think with those addressed this looks good to me.

Given we need to do a breaking release anyhow for f221479, if this is updated soonish we can get it into 0.56.

Or alternatively, if you don't have the time, let me know and I can fix up the review comments myself.

The other great thing to do would be to have a documentation section in the book about this, how to use it and so on.

I don't think I want to block on that but I think it'd be great to add if any of you have the cycles.

Thanks again and sorry for the lag.

emilio · 2020-11-13T19:06:44Z

src/codegen/mod.rs

@@ -4356,6 +4403,35 @@ mod utils {
        args
    }

+    pub fn fnsig_argument_identifiers(


Could you document what this returns? The signature is not super-self-descriptive.

emilio · 2020-11-13T19:07:47Z

src/codegen/mod.rs

@@ -3948,11 +3978,28 @@ pub(crate) fn codegen(
            &(),
        );

+        if context.options().dynamic_library_name.is_some() {


nit: if let Some(ref lib_name) = context.options().dynamic_library_name {.

Then use that instead of unwrapping around.

emilio · 2020-11-13T19:08:22Z

src/codegen/mod.rs

+                    "Check",
+                    context.options().dynamic_library_name.as_ref().unwrap(),
+                ]
+                .join(""),


just format!("Check{}", lib_name)?

emilio · 2020-11-13T19:08:58Z

src/codegen/dyngen.rs

+        }
+    }
+
+    pub fn add_function(


Maybe just push in order to match the result function name?

emilio · 2020-11-13T19:09:32Z

src/codegen/dyngen.rs

+    init_fields: Vec<proc_macro2::TokenStream>,
+}
+
+impl Default for DynamicItems {


Derive this?

jsimmons · 2020-11-14T12:57:10Z

src/codegen/dyngen.rs

+        ret: proc_macro2::TokenStream,
+        ret_ty: proc_macro2::TokenStream,
+    ) {
+        assert_eq!(args.len(), args_identifiers.len());


Just a note, this seems to assert on varargs parameters.

Not sure if those are not supported widely and this is expected? At least things seem to work when I remove the assert. The following snippet will trigger the assert.

int thing(int, ...);

emilio · 2020-11-25T13:41:28Z

I pushed this with my review comments addressed. Will send a follow-up for the var-args issue mentioned by @jsimmons above.

emilio · 2020-11-25T13:41:50Z

Thanks for all your work @joechrisellis (and everyone else who contributed and helped flesh out issues!)

hug-dev · 2020-11-25T13:52:35Z

Nice!! 🥳 🥳 🥳
Thanks @joechrisellis , @emilio and everybody involved!

emilio · 2020-11-25T14:01:05Z

#1931 addresses the varargs functions (requires a bit of an API change but I think it's fine and the result is simpler).

joechrisellis marked this pull request as draft July 27, 2020 12:52

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libloading support #1541

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goto-bus-stop mentioned this pull request Aug 8, 2020

Dynamically loading N-API functions neon-bindings/neon#584

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hug-dev mentioned this pull request Aug 26, 2020

types: Fix CK_LONG/CK_ULONG on Linux ARM32 mheese/rust-pkcs11#40

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emilio requested changes Oct 27, 2020

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Joe Ellis and others added 2 commits October 27, 2020 18:17

Add dynamic loading support

a086e56

Co-authored-by: Michael-F-Bryan <[email protected]>

Add tests for dynamic binding generation

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emilio approved these changes Nov 13, 2020

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emilio mentioned this pull request Nov 13, 2020

wasm32 c++ constructors missing return values #1912

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emilio closed this in fc5fa9a Nov 25, 2020

emilio mentioned this pull request Nov 25, 2020

Publish release that depends on cfg-if v1.0 #1925

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Cldfire mentioned this pull request Dec 2, 2020

Unclear whether or not libloading wrapper struct should have publicly accessible fields #1937

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hug-dev mentioned this pull request Dec 10, 2020

New safe and idiomatic interface mheese/rust-pkcs11#43

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dtolnay mentioned this pull request Jan 3, 2021

Consider a libloading-based dynamic mode dtolnay/cxx#655

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		// Finally, only generate dynamic bindings for functions (for now! this could
		// change in the future to support variables).

Add dynamic loading support #1846

Add dynamic loading support #1846

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joechrisellis commented Jul 27, 2020

Implementation

Example

Multiple Dynamically Loaded Libraries

dergroncki commented Aug 2, 2020

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emilio commented Nov 25, 2020

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