fix pathop fuzz timeout

R=caryclark@google.com

Bug:855751
Change-Id: Ieb6bae50311f62c9b03b84b2cf84f09ad2db2e46
Reviewed-on: https://skia-review.googlesource.com/137361
Reviewed-by: Cary Clark <caryclark@skia.org>
Commit-Queue: Cary Clark <caryclark@skia.org>
Auto-Submit: Cary Clark <caryclark@skia.org>

4 files changed, 24 insertions, 8 deletions

diff --git a/src/pathops/SkOpSegment.cpp b/src/pathops/SkOpSegment.cpp
index bfbf9dc687..3bd925c0c3 100644
--- a/src/pathops/SkOpSegment.cpp
+++ b/src/pathops/SkOpSegment.cpp
@@ -599,7 +599,7 @@ SkOpSegment* SkOpSegment::findNextOp(SkTDArray<SkOpSpanBase*>* chase, SkOpSpanBa
             continue;
         }
         if (!activeAngle) {
-            (void) nextSegment->markAndChaseDone(nextAngle->start(), nextAngle->end());
+            (void) nextSegment->markAndChaseDone(nextAngle->start(), nextAngle->end(), nullptr);
         }
         SkOpSpanBase* last = nextAngle->lastMarked();
         if (last) {
@@ -695,7 +695,7 @@ SkOpSegment* SkOpSegment::findNextWinding(SkTDArray<SkOpSpanBase*>* chase,
             continue;
         }
         if (!activeAngle) {
-            (void) nextSegment->markAndChaseDone(nextAngle->start(), nextAngle->end());
+            (void) nextSegment->markAndChaseDone(nextAngle->start(), nextAngle->end(), nullptr);
         }
         SkOpSpanBase* last = nextAngle->lastMarked();
         if (last) {
@@ -843,7 +843,7 @@ void SkOpSegment::markAllDone() {
     } while ((span = span->next()->upCastable()));
 }
 
-SkOpSpanBase* SkOpSegment::markAndChaseDone(SkOpSpanBase* start, SkOpSpanBase* end) {
+ bool SkOpSegment::markAndChaseDone(SkOpSpanBase* start, SkOpSpanBase* end, SkOpSpanBase** found) {
     int step = start->step(end);
     SkOpSpan* minSpan = start->starter(end);
     markDone(minSpan);
@@ -851,19 +851,29 @@ SkOpSpanBase* SkOpSegment::markAndChaseDone(SkOpSpanBase* start, SkOpSpanBase* e
     SkOpSegment* other = this;
     SkOpSpan* priorDone = nullptr;
     SkOpSpan* lastDone = nullptr;
+    int safetyNet = 100000;
     while ((other = other->nextChase(&start, &step, &minSpan, &last))) {
+        if (!--safetyNet) {
+            return false;
+        }
         if (other->done()) {
             SkASSERT(!last);
             break;
         }
         if (lastDone == minSpan || priorDone == minSpan) {
-            return nullptr;
+            if (found) {
+                *found = nullptr;
+            }
+            return true;
         }
         other->markDone(minSpan);
         priorDone = lastDone;
         lastDone = minSpan;
     }
-    return last;
+    if (found) {
+        *found = last;
+    }
+    return true;
 }
 
 bool SkOpSegment::markAndChaseWinding(SkOpSpanBase* start, SkOpSpanBase* end, int winding,
diff --git a/src/pathops/SkOpSegment.h b/src/pathops/SkOpSegment.h
index a68b30a289..a38d785250 100644
--- a/src/pathops/SkOpSegment.h
+++ b/src/pathops/SkOpSegment.h
@@ -274,7 +274,7 @@ public:
     }
 
     void markAllDone();
-    SkOpSpanBase* markAndChaseDone(SkOpSpanBase* start, SkOpSpanBase* end);
+    bool markAndChaseDone(SkOpSpanBase* start, SkOpSpanBase* end, SkOpSpanBase** found);
     bool markAndChaseWinding(SkOpSpanBase* start, SkOpSpanBase* end, int winding,
             SkOpSpanBase** lastPtr);
     bool markAndChaseWinding(SkOpSpanBase* start, SkOpSpanBase* end, int winding,
diff --git a/src/pathops/SkPathOpsOp.cpp b/src/pathops/SkPathOpsOp.cpp
index 09c6f0e1ce..f8b8a65eec 100644
--- a/src/pathops/SkPathOpsOp.cpp
+++ b/src/pathops/SkPathOpsOp.cpp
@@ -157,7 +157,10 @@ static bool bridgeOp(SkOpContourHead* contourList, const SkPathOp op,
                 }
                 simple->finishContour();
             } else {
-                SkOpSpanBase* last = current->markAndChaseDone(start, end);
+                SkOpSpanBase* last;
+                if (!current->markAndChaseDone(start, end, &last)) {
+                    return false;
+                }
                 if (last && !last->chased()) {
                     last->setChased(true);
                     SkASSERT(!SkPathOpsDebug::ChaseContains(chase, last));
diff --git a/src/pathops/SkPathOpsSimplify.cpp b/src/pathops/SkPathOpsSimplify.cpp
index d9d0879986..bfb3b8d7c1 100644
--- a/src/pathops/SkPathOpsSimplify.cpp
+++ b/src/pathops/SkPathOpsSimplify.cpp
@@ -58,7 +58,10 @@ static bool bridgeWinding(SkOpContourHead* contourList, SkPathWriter* simple) {
                 }
                 simple->finishContour();
             } else {
-                SkOpSpanBase* last = current->markAndChaseDone(start, end);
+                SkOpSpanBase* last;
+                if (!current->markAndChaseDone(start, end, &last)) {
+                    return false;
+                }
                 if (last && !last->chased()) {
                     last->setChased(true);
                     SkASSERT(!SkPathOpsDebug::ChaseContains(chase, last));