Fix for test and small tweak to not set last to corrupted sequence. A…

…lso small bug fix for leaking fd

Signed-off-by: Derek Collison <derek@nats.io>

server/filestore.go

@@ -1032,7 +1032,7 @@ func (mb *msgBlock) rebuildStateLocked() (*LostStreamData, error) {
 			fd = mb.mfd
 		} else {
 			fd, err = os.OpenFile(mb.mfn, os.O_RDWR, defaultFilePerms)
-			if err != nil {
+			if err == nil {
 				defer fd.Close()
 			}
 		}
@@ -1114,9 +1114,11 @@ func (mb *msgBlock) rebuildStateLocked() (*LostStreamData, error) {
 			_, deleted = mb.dmap[seq]
 		}
 
-		// Always set last.
-		mb.last.seq = seq
-		mb.last.ts = ts
+		// Always set last if not > startLastSeq
+		if seq <= startLastSeq {
+			mb.last.seq = seq
+			mb.last.ts = ts
+		}
 
 		if !deleted {
 			data := buf[index+msgHdrSize : index+rl]

server/filestore_test.go

@@ -1278,7 +1278,10 @@ func TestFileStoreBitRot(t *testing.T) {
 			// Now twiddle some bits.
 			fs.mu.Lock()
 			lmb := fs.lmb
-			contents, _ := os.ReadFile(lmb.mfn)
+			contents, err := os.ReadFile(lmb.mfn)
+			require_NoError(t, err)
+			require_True(t, len(contents) > 0)
+
 			var index int
 			for {
 				index = rand.Intn(len(contents))
@@ -1296,6 +1299,10 @@ func TestFileStoreBitRot(t *testing.T) {
 			if len(ld.Msgs) > 0 {
 				break
 			}
+			// If our bitrot caused us to not be able to recover any messages we can break as well.
+			if state := fs.State(); state.Msgs == 0 {
+				break
+			}
 			// Fail the test if we have tried the 10 times and still did not
 			// get any corruption report.
 			if i == 9 {
@@ -1314,7 +1321,10 @@ func TestFileStoreBitRot(t *testing.T) {
 
 		// checkMsgs will repair the underlying store, so checkMsgs should be clean now.
 		if ld := fs.checkMsgs(); ld != nil {
-			t.Fatalf("Expected no errors restoring checked and fixed filestore, got %+v", ld)
+			// If we have no msgs left this will report the head msgs as lost again.
+			if state := fs.State(); state.Msgs > 0 {
+				t.Fatalf("Expected no errors restoring checked and fixed filestore, got %+v", ld)
+			}
 		}
 	})
 }