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stepcompress: Do 32bit integer overflow checks internally in C code 

Update the stepcompress C code to check for integer overflow so that
the python code does not need to.  The new checks also handle the
possibility of a single move lasting long enough to cause an overflow.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
This commit is contained in:
Kevin O'Connor 2016-11-01 23:08:16 -04:00
parent 8025921fc8
commit 508a934d62
1 changed files with 31 additions and 10 deletions
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41
klippy/stepcompress.c
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@ -134,21 +134,23 @@ struct step_move {
static struct step_move
compress_bisect_add(struct stepcompress *sc)
{
uint64_t *last = sc->queue_next;
if (last > sc->queue_pos + 65535)
last = sc->queue_pos + 65535;
struct points point = minmax_point(sc, sc->queue_pos);
int32_t outer_mininterval = point.minp, outer_maxinterval = point.maxp;
int32_t add = 0, minadd = -0x8001, maxadd = 0x8000;
int32_t bestinterval = 0, bestcount = 1, bestadd = 0, bestreach = INT32_MIN;
int32_t checked_count = 0;
for (;;) {
// Find longest valid sequence with the given 'add'
int32_t mininterval = outer_mininterval, maxinterval = outer_maxinterval;
int32_t count = 1, addfactor = 0;
for (;;) {
if (sc->queue_pos + count >= last)
return (struct step_move){ maxinterval, count, add };
if (count > checked_count) {
if (&sc->queue_pos[count] >= sc->queue_next || count >= 65535
|| sc->queue_pos[count] >= sc->last_step_clock + (3<<28))
return (struct step_move){ maxinterval, count, add };
checked_count++;
}
point = minmax_point(sc, sc->queue_pos + count);
addfactor += count;
int32_t c = add*addfactor;
@ -221,23 +223,37 @@ check_line(struct stepcompress *sc, struct step_move move)
{
if (!CHECK_LINES)
return;
if (move.count == 1) {
if (move.interval != (uint32_t)(*sc->queue_pos - sc->last_step_clock)
|| *sc->queue_pos < sc->last_step_clock) {
fprintf(stderr, "ERROR: Count 1 point out of range: %d %d %d\n"
, move.interval, move.count, move.add);
sc->errors++;
}
return;
}
int err = 0;
if (!move.count || !move.interval || move.interval >= 0x80000000) {
fprintf(stderr, "ERROR: Point out of range: %d %d %d\n"
, move.interval, move.count, move.add);
err++;
}
uint32_t interval = move.interval, p = interval;
uint32_t interval = move.interval, p = 0;
uint16_t i;
for (i=0; i<move.count; i++) {
struct points point = minmax_point(sc, sc->queue_pos + i);
p += interval;
if (p < point.minp || p > point.maxp) {
fprintf(stderr, "ERROR: Point %d of %d: %d not in %d:%d\n"
, i+1, move.count, p, point.minp, point.maxp);
err++;
}
if (interval >= 0x80000000) {
fprintf(stderr, "ERROR: Point %d of %d: interval overflow %d\n"
, i+1, move.count, interval);
err++;
}
interval += move.add;
p += interval;
}
sc->errors += err;
}
@ -361,11 +377,16 @@ stepcompress_flush(struct stepcompress *sc, uint64_t move_clock)
};
struct queue_message *qm = message_alloc_and_encode(msg, 5);
qm->min_clock = qm->req_clock = sc->last_step_clock;
if (move.count == 1 && sc->last_step_clock + (1<<27) < *sc->queue_pos) {
// Be careful with 32bit overflow
sc->last_step_clock = qm->req_clock = *sc->queue_pos;
} else {
uint32_t addfactor = move.count*(move.count-1)/2;
uint32_t ticks = move.add*addfactor + move.interval*move.count;
sc->last_step_clock += ticks;
}
list_add_tail(&qm->node, &sc->msg_queue);
uint32_t addfactor = move.count*(move.count-1)/2;
uint32_t ticks = move.add*addfactor + move.interval*move.count;
sc->last_step_clock += ticks;
if (sc->queue_pos + move.count >= sc->queue_next) {
sc->queue_pos = sc->queue_next = sc->queue;
break;