Device passthrough and root checks

osspecifics/osspecifics.go

@@ -0,0 +1,73 @@
+//go:build !windows
+
+package osspecifics
+
+import (
+	"fmt"
+	"os"
+	"os/exec"
+	"os/user"
+	"path/filepath"
+	"strings"
+	"syscall"
+
+	"github.com/pkg/errors"
+)
+
+func SetNewProcessGroupCmd(cmd *exec.Cmd) {
+	// This is to prevent Ctrl+C propagating to the child process.
+	cmd.SysProcAttr = &syscall.SysProcAttr{
+		Setpgid: true,
+	}
+}
+
+func TerminateProcess(pid int) error {
+	return syscall.Kill(-pid, syscall.SIGTERM)
+}
+
+// This is never used except for a band-aid that would check
+// that there are no double-mounts.
+func CheckDeviceSeemsMounted(devPathPrefix string) (bool, error) {
+	// Quite a bit hacky implementation, but it's to be used as a failsafe band-aid anyway.
+	absDevPathPrefix, err := filepath.Abs(devPathPrefix)
+	if err != nil {
+		return false, errors.Wrap(err, "get abs path")
+	}
+
+	mounts, err := exec.Command("mount").Output()
+	if err != nil {
+		return false, errors.Wrap(err, "run mount command")
+	}
+
+	for _, line := range strings.Split(string(mounts), "\n") {
+		// I know, I know, this is a rare band-aid.
+		if strings.HasPrefix(line, devPathPrefix) || strings.HasPrefix(line, absDevPathPrefix) {
+			return true, nil
+		}
+	}
+
+	return false, nil
+}
+
+func CheckValidDevicePath(devPath string) error {
+	stat, err := os.Stat(devPath)
+	if err != nil {
+		return errors.Wrap(err, "stat path")
+	}
+
+	isDev := stat.Mode()&os.ModeDevice != 0
+	if !isDev {
+		fmt.Errorf("file mode is not device (%v)", stat.Mode())
+	}
+
+	return nil
+}
+
+func CheckRunAsRoot() (bool, error) {
+	currentUser, err := user.Current()
+	if err != nil {
+		return false, errors.Wrap(err, "get current user")
+	}
+
+	return currentUser.Username == "root", nil
+}