1 files changed, 77 insertions, 0 deletions
diff --git a/vendor/github.com/cilium/ebpf/internal/pinning.go b/vendor/github.com/cilium/ebpf/internal/pinning.go
new file mode 100644
index 000000000..c711353c3
--- /dev/null
+++ b/vendor/github.com/cilium/ebpf/internal/pinning.go
@@ -0,0 +1,77 @@
+package internal
+
+import (
+	"errors"
+	"fmt"
+	"os"
+	"path/filepath"
+	"runtime"
+	"unsafe"
+
+	"github.com/cilium/ebpf/internal/sys"
+	"github.com/cilium/ebpf/internal/unix"
+)
+
+func Pin(currentPath, newPath string, fd *sys.FD) error {
+	const bpfFSType = 0xcafe4a11
+
+	if newPath == "" {
+		return errors.New("given pinning path cannot be empty")
+	}
+	if currentPath == newPath {
+		return nil
+	}
+
+	var statfs unix.Statfs_t
+	if err := unix.Statfs(filepath.Dir(newPath), &statfs); err != nil {
+		return err
+	}
+
+	fsType := int64(statfs.Type)
+	if unsafe.Sizeof(statfs.Type) == 4 {
+		// We're on a 32 bit arch, where statfs.Type is int32. bpfFSType is a
+		// negative number when interpreted as int32 so we need to cast via
+		// uint32 to avoid sign extension.
+		fsType = int64(uint32(statfs.Type))
+	}
+
+	if fsType != bpfFSType {
+		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
+}