//go:build ignore
// +build ignore
package main
import (
“crypto/sha256”
“fmt”
“io”
“os”
“os/exec”
)
func main() {
fullPath, err := getGoExeFullPath()
if err != nil {
fmt.Println(“Error:”, err)
return
}
fmt.Printf("found go binary: %s\n", fullPath)
hash, err := hashFile(fullPath)
if err != nil {
fmt.Println("Error:", err)
return
}
data := fmt.Sprintf("sha256:%s", hash)
fmt.Printf("saving go binary hash: %s\n", data)
err = os.WriteFile("gobinhash", []byte(data), 0644)
if err != nil {
fmt.Println("Error:", err)
return
}
}
const (
goBinName = “go”
goEnvCmd = “env”
goRootEnvVar = “GOROOT”
goBinPathPat = “%s/bin/%s”
)
func getGoExeFullPath() (string, error) {
output, err := exec.Command(goBinName, goEnvCmd, goRootEnvVar).Output()
if err != nil {
return “”, err
}
goRoot := string(output[:len(output)-1]) // removing the newline
fullPath := fmt.Sprintf(goBinPathPat, goRoot, goBinName)
if _, err := os.Stat(fullPath); err == nil {
return fullPath, nil
}
return exec.LookPath(goBinName)
}
func hashFile(fullPath string) (string, error) {
file, err := os.Open(fullPath)
if err != nil {
return “”, err
}
defer file.Close()
hasher := sha256.New()
if _, err := io.Copy(hasher, file); err != nil {
return "", err
}
hash := hasher.Sum(nil)
return fmt.Sprintf("%x", hash), nil
}
