purego
A library for calling C functions from Go without Cgo.
Motivation
The Ebitengine game engine was ported to use only Go on Windows. This enabled
cross-compiling to Windows from any other operating system simply by setting GOOS=windows. The purego project was
born to bring that same vision to the other platforms supported by Ebitengine.
Benefits
- Simple Cross-Compilation: No C means you can build for other platforms easily without a C compiler.
- Faster Compilation: Efficiently cache your entirely Go builds.
- Smaller Binaries: Using Cgo generates a C wrapper function for each C function called. Purego doesn't!
- Dynamic Linking: Load symbols at runtime and use it as a plugin system.
- Foreign Function Interface: Call into other languages that are compiled into shared objects.
Example
package main
import (
"fmt"
"runtime"
"github.com/ebitengine/purego"
)
func getSystemLibrary() string {
switch runtime.GOOS {
case "darwin":
return "/usr/lib/libSystem.B.dylib"
case "linux":
return "libc.so.6"
default:
panic(fmt.Errorf("GOOS=%s is not supported", runtime.GOOS))
}
}
func main() {
libc, err := purego.Dlopen(getSystemLibrary(), purego.RTLD_NOW|purego.RTLD_GLOBAL)
if err != nil {
panic(err)
}
var puts func(string)
purego.RegisterLibFunc(&puts, libc, "puts")
puts("Calling C from Go without Cgo!")
}
Then to run: CGO_ENABLED=0 go run main.go
External Code
Purego uses code that originates from the Go runtime. These files are under the BSD-3 License that can be found in the Go Source. This is a list of the copied files:
zcallback_darwin_*.sfrom packageruntimeinternal/abi/abi_*.hfrom packageruntime/cgointernal/fakecgo/asm_GOARCH.sfrom packageruntime/cgointernal/fakecgo/callbacks.gofrom packageruntime/cgointernal/fakecgo/go_GOOS_GOARCH.gofrom packageruntime/cgointernal/fakecgo/iscgo.gofrom packageruntime/cgointernal/fakecgo/setenv.gofrom packageruntime/cgo