upstream/mercurial-mirror Files · contrib/fuzz/bdiff.cc

phases: avoid N² behavior in `advanceboundary`...

phases: avoid N² behavior in `advanceboundary` We allowed duplicated entries in the deque, which each entry could potentially insert all its ancestors. So advancing boundary for the full repository would mean each revision would walk all its ancestors, resulting in O(N²) iteration. For repository of any decent size, N² is quickly insane. We introduce a simple set to avoid this and get back to reasonable performance.

Augie Fackler - - Load All Authors

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      /*

       * bdiff.cc - fuzzer harness for bdiff.c

       *

       * Copyright 2018, Google Inc.

       *

       * This software may be used and distributed according to the terms of

       * the GNU General Public License, incorporated herein by reference.

       */

      #include <memory>

      #include <stdlib.h>

      #include "FuzzedDataProvider.h"

      extern "C" {

      #include "bdiff.h"

      extern "C" int LLVMFuzzerInitialize(int *argc, char ***argv)

      {

      	return 0;

      }

      int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size)

      {

      	FuzzedDataProvider provider(Data, Size);

      	std::string left = provider.ConsumeRandomLengthString(Size);

      	std::string right = provider.ConsumeRemainingBytesAsString();

      	struct bdiff_line *a, *b;

      	int an = bdiff_splitlines(left.c_str(), left.size(), &a);

      	int bn = bdiff_splitlines(right.c_str(), right.size(), &b);

      	struct bdiff_hunk l;

      	bdiff_diff(a, an, b, bn, &l);

      	free(a);

      	free(b);

      	bdiff_freehunks(l.next);

      	return 0; // Non-zero return values are reserved for future use.

      }

      } // extern "C"

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				/*
				* bdiff.cc - fuzzer harness for bdiff.c
				*
				* Copyright 2018, Google Inc.
				*
				* This software may be used and distributed according to the terms of
				* the GNU General Public License, incorporated herein by reference.
				*/
				#include <memory>
				#include <stdlib.h>

				#include "FuzzedDataProvider.h"

				extern "C" {
				#include "bdiff.h"

				extern "C" int LLVMFuzzerInitialize(int argc, char **argv)
				{
				return 0;
				}

				int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size)
				{
				FuzzedDataProvider provider(Data, Size);
				std::string left = provider.ConsumeRandomLengthString(Size);
				std::string right = provider.ConsumeRemainingBytesAsString();

				struct bdiff_line a, b;
				int an = bdiff_splitlines(left.c_str(), left.size(), &a);
				int bn = bdiff_splitlines(right.c_str(), right.size(), &b);
				struct bdiff_hunk l;
				bdiff_diff(a, an, b, bn, &l);
				free(a);
				free(b);
				bdiff_freehunks(l.next);
				return 0; // Non-zero return values are reserved for future use.
				}

				} // extern "C"