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-rw-r--r--tools/fuzzing/libfuzzer/FuzzerCrossOver.cpp51
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diff --git a/tools/fuzzing/libfuzzer/FuzzerCrossOver.cpp b/tools/fuzzing/libfuzzer/FuzzerCrossOver.cpp
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+//===- FuzzerCrossOver.cpp - Cross over two test inputs -------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+// Cross over test inputs.
+//===----------------------------------------------------------------------===//
+
+#include "FuzzerDefs.h"
+#include "FuzzerMutate.h"
+#include "FuzzerRandom.h"
+#include <cstring>
+
+namespace fuzzer {
+
+// Cross Data1 and Data2, store the result (up to MaxOutSize bytes) in Out.
+size_t MutationDispatcher::CrossOver(const uint8_t *Data1, size_t Size1,
+ const uint8_t *Data2, size_t Size2,
+ uint8_t *Out, size_t MaxOutSize) {
+ assert(Size1 || Size2);
+ MaxOutSize = Rand(MaxOutSize) + 1;
+ size_t OutPos = 0;
+ size_t Pos1 = 0;
+ size_t Pos2 = 0;
+ size_t *InPos = &Pos1;
+ size_t InSize = Size1;
+ const uint8_t *Data = Data1;
+ bool CurrentlyUsingFirstData = true;
+ while (OutPos < MaxOutSize && (Pos1 < Size1 || Pos2 < Size2)) {
+ // Merge a part of Data into Out.
+ size_t OutSizeLeft = MaxOutSize - OutPos;
+ if (*InPos < InSize) {
+ size_t InSizeLeft = InSize - *InPos;
+ size_t MaxExtraSize = std::min(OutSizeLeft, InSizeLeft);
+ size_t ExtraSize = Rand(MaxExtraSize) + 1;
+ memcpy(Out + OutPos, Data + *InPos, ExtraSize);
+ OutPos += ExtraSize;
+ (*InPos) += ExtraSize;
+ }
+ // Use the other input data on the next iteration.
+ InPos = CurrentlyUsingFirstData ? &Pos2 : &Pos1;
+ InSize = CurrentlyUsingFirstData ? Size2 : Size1;
+ Data = CurrentlyUsingFirstData ? Data2 : Data1;
+ CurrentlyUsingFirstData = !CurrentlyUsingFirstData;
+ }
+ return OutPos;
+}
+
+} // namespace fuzzer