[#2095] node: Fix collecting child objects

Stop child objects collection if the last returned object (the most "left"
object in the collected chain) starts exactly from the `GETRANGE`'s `from`
value.

Signed-off-by: Pavel Karpy <carpawell@nspcc.ru>

CHANGELOG.md

@@ -51,6 +51,8 @@ Changelog for NeoFS Node
 - `neofs-cli container create ` check the sufficiency of the number of nodes in the selector for replicas (#2038)
 - Data duplication during request forwarding (#2047)
 - Tree service panic on `TreeMove` operation (#2140)
+- Panic in `GETRANGE` with zero length (#2095)
+- Spawning useless `GETRANGE` with zero length for a big object (#2101)
 
 ### Removed
 - `-g` option from `neofs-cli control ...` and `neofs-cli container create` commands (#2089)

pkg/services/object/get/assemble.go

@@ -203,7 +203,9 @@ func (exec *execCtx) buildChainInReverse(prev oid.ID) ([]oid.ID, []objectSDK.Ran
 
 	// fill the chain end-to-start
 	for withPrev {
-		if exec.curOff < from {
+		// check that only for "range" requests,
+		// for `GET` it stops via the false `withPrev`
+		if seekRng != nil && exec.curOff <= from {
 			break
 		}
 

pkg/services/object/get/get_test.go

@@ -963,7 +963,7 @@ func TestGetRemoteSmall(t *testing.T) {
 				addr.SetObject(oidtest.ID())
 
 				srcObj := generateObject(addr, nil, nil)
-				srcObj.SetPayloadSize(10)
+				srcObj.SetPayloadSize(11)
 
 				ns, as := testNodeMatrix(t, []int{2})