Add purego support for unix

raylib/purego_unix.go

@@ -0,0 +1,45 @@
+//go:build !cgo && (darwin || openbsd || freebsd || linux)
+
+package rl
+
+import (
+	"fmt"
+	"runtime"
+	"unsafe"
+
+	"github.com/ebitengine/purego"
+	"golang.org/x/sys/unix"
+)
+
+// loadLibrary loads the raylib dll and panics on error
+func loadLibrary() uintptr {
+	libname := "raylib.so"
+	switch runtime.GOOS {
+	case "darwin":
+		libname = "raylib.dylib"
+	}
+
+	handle, err := purego.Dlopen(libname, purego.RTLD_NOW|purego.RTLD_GLOBAL)
+	if err != nil {
+		panic(fmt.Errorf("cannot load library %s: %w", libname, err))
+	}
+
+	proc, err := purego.Dlsym(handle, "raylib_version")
+	if err != nil {
+		panic(err)
+	}
+
+	version := unix.BytePtrToString(**(***byte)(unsafe.Pointer(&proc)))
+	if version != requiredVersion {
+		panic(fmt.Errorf("version %s of %s doesn't match the required version %s", version, libname, requiredVersion))
+	}
+
+	return uintptr(handle)
+}
+
+func traceLogCallbackWrapper(fn TraceLogCallbackFun) uintptr {
+	return purego.NewCallback(func(logLevel int32, text *byte) uintptr {
+		fn(int(logLevel), unix.BytePtrToString(text))
+		return 0
+	})
+}