[#52] object/range: Add full range option to parameters

Add FullRange option to get range operation parameters that allows to get
payload range [0:object_size] w/o the actual knowledge of the object size.

Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>

pkg/services/object/range/prm.go

@@ -5,7 +5,7 @@ import (
 )
 
 type Prm struct {
-	local bool
+	local, full bool
 
 	addr *object.Address
 
@@ -37,3 +37,11 @@ func (p *Prm) WithRange(v *object.Range) *Prm {
 
 	return p
 }
+
+func (p *Prm) FullRange() *Prm {
+	if p != nil {
+		p.full = true
+	}
+
+	return p
+}

pkg/services/object/range/service.go

@@ -64,12 +64,16 @@ func (s *Service) GetRange(ctx context.Context, prm *Prm) (*Result, error) {
 		return nil, errors.Wrapf(err, "(%T) could not receive Head result", s)
 	}
 
-	off, ln := prm.rng.GetOffset(), prm.rng.GetLength()
-
 	origin := headResult.Header()
 
 	originSize := origin.GetPayloadSize()
-	if originSize < off+ln {
+
+	if prm.full {
+		prm.rng = new(object.Range)
+		prm.rng.SetLength(originSize)
+	}
+
+	if originSize < prm.rng.GetOffset()+prm.rng.GetLength() {
 		return nil, errors.Errorf("(%T) requested payload range is out-of-bounds", s)
 	}