This feature has been added to Cargo and was stabilized in Cargo 1.56. The accepted answer is now out-of-date. Linker arguments can be specified in build.rs like so: // Pass `-fopenmp` to the linker. println!(“cargo:rustc-link-arg=-fopenmp”);
By default Rust assumes *mut T is not safe to send between threads, and this means structs containing it are not safe either. You can tell Rust that it is safe indeed: unsafe impl Send for Storage {} It relies entirely on your knowledge of how C uses data behind this pointer. Implementing Send means … Read more
The gem install ffi fails due to the gem trying to build a bundled copy of libffi, which does not work due to assumptions that /usr/bin/env exists and too old libffi copy. However, you can build the ffi gem against the system libffi – install the packages: apt install clang make ruby-dev libffi-dev After that … Read more
First, some logical errors with the code: It is not correct to cast pointers to i32 on many platforms (like 64-bit). Pointers may use all of those bits. Truncating a pointer and then calling a function at the truncated address will lead to Really Bad Things. Generally you want to use a machine-sized integer (usize … Read more
The Rust Programming Language, first edition, has a section about FFI titled Callbacks from C code to Rust functions. The example from there is extern “C” fn callback(a: i32) { println!(“I’m called from C with value {0}”, a); } #[link(name = “extlib”)] extern “C” { fn register_callback(cb: extern “C” fn(i32)) -> i32; fn trigger_callback(); } … Read more
Answering my own question. I fixed the ffi issue by uninstalling my faulty Ruby version and CocoaPods, then I used the -x86_64 arch to reinstall ffi and CocoaPods. These are the steps I did to get back to a working state (and to apply the M1 workarounds for ffi): Uninstall Ruby with: brew uninstall ruby … Read more
You asked what is the portable way to call any function pointer with given number of arguments. The correct answer is that there is no such way. For example python is able to call C functions through the ctypes module, but this is portable only for as long as you know the exact prototype and … Read more
Ideally you would use std::alloc::alloc because you can then specify the desired alignment as part of the layout: pub unsafe fn alloc(layout: Layout) -> *mut u8 The main downside is that you need to know the alignment, even when you free the allocation. It’s common practice to use a Vec as an easy allocation mechanism, … Read more
Here is a working example: wrapper.h (C & C++ aware) #ifndef WRAPPER_H_ #define WRAPPER_H_ #ifdef __cplusplus extern “C” { #endif typedef struct CPPClass CPPClass; CPPClass* CPPClass_new(); void CPPClass_do_something(CPPClass* cppclass); int CPPClass_get_state(CPPClass* cppclass); void CPPClass_delete(CPPClass* cppclass); #ifdef __cplusplus } #endif #endif /* WRAPPER_H_ */ wrapper.cpp (C++ only) #include “wrapper.h” class CPPClass { int state; public: CPPClass(): … Read more
The best way to work with C strings in Rust is to use structures from the std::ffi module, namely CStr and CString. CStr is a dynamically sized type and so it can only be used through a pointer. This makes it very similar to the regular str type. You can construct a &CStr from *const … Read more