adds code and test to detect logical clock overflow

we don't expect it to be possible to have CRDB
generate 4B conflicts

internal/datastore/revisions/hlcrevision.go

@@ -56,11 +56,15 @@ func parseHLCRevisionString(revisionStr string) (datastore.Revision, error) {
 	}
 
 	paddedLogicalClockStr := pieces[1] + strings.Repeat("0", logicalClockLength-len(pieces[1]))
-	logicalclock, err := strconv.ParseUint(paddedLogicalClockStr, 10, 32)
+	logicalclock, err := strconv.ParseUint(paddedLogicalClockStr, 10, 64)
 	if err != nil {
 		return datastore.NoRevision, fmt.Errorf("invalid revision string: %q", revisionStr)
 	}
 
+	if logicalclock > math.MaxUint32 {
+		return datastore.NoRevision, spiceerrors.MustBugf("received logical lock that exceeds MaxUint32 (%d > %d): revision %q", logicalclock, math.MaxUint32, revisionStr)
+	}
+
 	uintLogicalClock, err := safecast.ToUint32(logicalclock)
 	if err != nil {
 		return datastore.NoRevision, spiceerrors.MustBugf("could not cast logicalclock to uint32: %v", err)

internal/datastore/revisions/hlcrevision_test.go

@@ -290,6 +290,13 @@ func TestHLCToFromDecimal(t *testing.T) {
 	}
 }
 
+func TestFailsIfLogicalClockExceedsMaxUin32(t *testing.T) {
+	expectedError := "received logical lock that exceeds MaxUint32 (9999999999 > 4294967295): revision \"0.9999999999\""
+	require.PanicsWithValue(t, expectedError, func() {
+		_, _ = HLCRevisionFromString("0.9999999999")
+	})
+}
+
 func BenchmarkHLCParsing(b *testing.B) {
 	tcs := []string{
 		"1",