skia2/fuzz/FuzzPathop.cpp
Kevin Lubick 416b248312 Avoid platform-dependent function params in Fuzzer
We use this approach instead of T next() because different compilers
evaluate function parameters in different orders. If fuzz->next()
returned 5 and then 7, foo(fuzz->next(), fuzz->next()) would be
foo(5, 7) when compiled on GCC and foo(7, 5) when compiled on Clang.
By requiring params to be passed in, we avoid the temptation to call 
next() in a way that does not consume fuzzed bytes in a single 
platform-independent order.

BUG=skia:

GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=4392

Change-Id: I35de849f82e8be45378f662a48100eb732fa8895
Reviewed-on: https://skia-review.googlesource.com/4392
Reviewed-by: Mike Klein <mtklein@chromium.org>
Commit-Queue: Kevin Lubick <kjlubick@google.com>
2016-11-10 22:52:03 +00:00

74 lines
1.7 KiB
C++

/*
* Copyright 2016 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "Fuzz.h"
#include "SkPath.h"
#include "SkPathOps.h"
const int kLastOp = SkPathOp::kReverseDifference_SkPathOp;
void BuildPath(Fuzz* fuzz,
SkPath* path,
int last_verb) {
while (!fuzz->exhausted()) {
// Use a uint8_t to conserve bytes. This makes our "fuzzed bytes footprint"
// smaller, which leads to more efficient fuzzing.
uint8_t operation;
fuzz->next(&operation);
SkScalar a,b,c,d,e,f;
switch (operation % (last_verb + 1)) {
case SkPath::Verb::kMove_Verb:
fuzz->next(&a, &b);
path->moveTo(a, b);
break;
case SkPath::Verb::kLine_Verb:
fuzz->next(&a, &b);
path->lineTo(a, b);
break;
case SkPath::Verb::kQuad_Verb:
fuzz->next(&a, &b, &c, &d);
path->quadTo(a, b, c, d);
break;
case SkPath::Verb::kConic_Verb:
fuzz->next(&a, &b, &c, &d, &e);
path->conicTo(a, b, c, d, e);
break;
case SkPath::Verb::kCubic_Verb:
fuzz->next(&a, &b, &c, &d, &e, &f);
path->cubicTo(a, b, c, d, e, f);
break;
case SkPath::Verb::kClose_Verb:
path->close();
break;
case SkPath::Verb::kDone_Verb:
// In this case, simply exit.
return;
}
}
}
DEF_FUZZ(Pathop, fuzz) {
SkOpBuilder builder;
uint8_t stragglerOp;
fuzz->next(&stragglerOp);
SkPath path;
BuildPath(fuzz, &path, SkPath::Verb::kDone_Verb);
builder.add(path, static_cast<SkPathOp>(stragglerOp % (kLastOp + 1)));
SkPath result;
builder.resolve(&result);
}