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
}