How can I change a functions ABI based on the target operating system?

Asked Jun 13 '18 at 07:15

Active Jun 13 '18 at 14:18

Viewed 76 times

I am writing a cross-platform library in Rust where I need to use specific ABI strings for Windows and Unix. My current solution is:

#[macro_export]
macro_rules! create_plugin {
    (@internal $name:ident) => {
        #[no_mangle]
        #[cfg(target_os = "windows")]
        pub unsafe extern "stdcall" fn Test(data: *const *const u32) -> bool {
            // Source 1
        }

        #[no_mangle]
        #[cfg(not(target_os = "windows"))]
        pub unsafe extern "C" fn Test(data: *const *const u32) -> bool {
            // Source 1 (duplicate)
        }
    }

    // ...
}

Is there any way to reduce the copy-and-pasted code in definitions?

edited Jun 13 '18 at 14:18

Shepmaster

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asked Jun 13 '18 at 07:15

xakdog

Why do you need your Windows version to be stdcall? You can just use cdecl (i.e. "C") in 32-bit without issues if the C-side declaration matches. And under 64-bit, stdcall doesn't do anything anymore. – Sebastian Redl Jun 13 '18 at 09:01
It’s a 32bit binary and I have no acces to source code. It expecting stdcall and crashes on cdecl. – xakdog Jun 13 '18 at 09:19
So you're writing a plugin for an existing program? – Sebastian Redl Jun 13 '18 at 10:49
Yes, it’s plugin for existing program – xakdog Jun 13 '18 at 12:04
1

TL;DR: more macros. – Shepmaster Jun 13 '18 at 14:19
@Shepmaster funny, but not clean. – xakdog Jun 13 '18 at 19:35
@xakdog no humor intended — macros are a primary solution to avoid repetition when existing abstractions aren't powerful enough. – Shepmaster Jun 13 '18 at 19:37
@Shepmaster finally I found a `"system"` convention that will interpreted as "stdcall" on win32 https://doc.rust-lang.org/book/first-edition/ffi.html#foreign-calling-conventions May be it's not an duplicate? – xakdog Jul 09 '18 at 06:22

How can I change a functions ABI based on the target operating system?

0 Answers0