whatcanGOwrong

go/pkg/mod/github.com/cilium/ebpf@v0.11.0/internal/pinning.go

@@ -0,0 +1,65 @@
+package internal
+
+import (
+	"errors"
+	"fmt"
+	"os"
+	"path/filepath"
+	"runtime"
+
+	"github.com/cilium/ebpf/internal/sys"
+	"github.com/cilium/ebpf/internal/unix"
+)
+
+func Pin(currentPath, newPath string, fd *sys.FD) error {
+	if newPath == "" {
+		return errors.New("given pinning path cannot be empty")
+	}
+	if currentPath == newPath {
+		return nil
+	}
+
+	fsType, err := FSType(filepath.Dir(newPath))
+	if err != nil {
+		return err
+	}
+	if fsType != unix.BPF_FS_MAGIC {
+		return fmt.Errorf("%s is not on a bpf filesystem", newPath)
+	}
+
+	defer runtime.KeepAlive(fd)
+
+	if currentPath == "" {
+		return sys.ObjPin(&sys.ObjPinAttr{
+			Pathname: sys.NewStringPointer(newPath),
+			BpfFd:    fd.Uint(),
+		})
+	}
+
+	// Renameat2 is used instead of os.Rename to disallow the new path replacing
+	// an existing path.
+	err = unix.Renameat2(unix.AT_FDCWD, currentPath, unix.AT_FDCWD, newPath, unix.RENAME_NOREPLACE)
+	if err == nil {
+		// Object is now moved to the new pinning path.
+		return nil
+	}
+	if !os.IsNotExist(err) {
+		return fmt.Errorf("unable to move pinned object to new path %v: %w", newPath, err)
+	}
+	// Internal state not in sync with the file system so let's fix it.
+	return sys.ObjPin(&sys.ObjPinAttr{
+		Pathname: sys.NewStringPointer(newPath),
+		BpfFd:    fd.Uint(),
+	})
+}
+
+func Unpin(pinnedPath string) error {
+	if pinnedPath == "" {
+		return nil
+	}
+	err := os.Remove(pinnedPath)
+	if err == nil || os.IsNotExist(err) {
+		return nil
+	}
+	return err
+}