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

filemerge: add support for partial conflict resolution by external tool...

filemerge: add support for partial conflict resolution by external tool A common class of merge conflicts is in imports/#includes/etc. It's relatively easy to write a tool that can resolve these conflicts, perhaps by naively just unioning the statements and leaving any cleanup to other tools to do later [1]. Such specialized tools cannot generally resolve all conflicts in a file, of course. Let's therefore call them "partial merge tools". Note that the internal simplemerge algorithm is such a partial merge tool - one that only resolves trivial "conflicts" where one side is unchanged or both sides change in the same way. One can also imagine having smarter language-aware partial tools that merge the AST. It may be useful for such tools to interactively let the user resolve any conflicts it can't resolve itself. However, having the option of implementing it as a partial merge tool means that the developer doesn't *need* to create a UI for it. Instead, the user can resolve any remaining conflicts with their regular merge tool (e.g. `:merge3` or `meld). We don't currently have a way to let the user define such partial merge tools. That's what this patch addresses. It lets the user configure partial merge tools to run. Each tool can be configured to run only on files matching certain patterns (e.g. "*.py"). The tool takes three inputs (local, base, other) and resolves conflicts by updating these in place. For example, let's say the inputs are these: base: ``` import sys def main(): print('Hello') ``` local: ``` import os import sys def main(): print('Hi') ``` other: ``` import re import sys def main(): print('Howdy') ``` A partial merge tool could now resolve the conflicting imports by replacing the import statements in *all* files by the following snippet, while leaving the remainder of the files unchanged. ``` import os import re import sys ``` As a result, simplemerge and any regular merge tool that runs after the partial merge tool(s) will consider the imports to be non-conflicting and will only present the conflict in `main()` to the user. Differential Revision: https://phab.mercurial-scm.org/D12356

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        Augie Fackler
    
fuzz: add a fuzzer for xdiff...

              r36697
            
      /*

       * xdiff.cc - fuzzer harness for thirdparty/xdiff

       *

       * 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 "thirdparty/xdiff/xdiff.h"

      #include <inttypes.h>

      #include <stdlib.h>

        Augie Fackler
    
fuzz: use a more standard approach to allow local builds of fuzzers...

              r44265
            
      #include "FuzzedDataProvider.h"

        Augie Fackler
    
fuzz: extract some common utilities and use modern C++ idioms...

              r38191
            
        Augie Fackler
    
fuzz: add a fuzzer for xdiff...

              r36697
            
      extern "C" {

        Augie Fackler
    
fuzz: always define LLVMFuzzerInitialize() even if we don't need it...

              r44261
            
      int LLVMFuzzerInitialize(int *argc, char ***argv)

      {

      	return 0;

      }

        Augie Fackler
    
fuzz: add a fuzzer for xdiff...

              r36697
            
      int hunk_consumer(long a1, long a2, long b1, long b2, void *priv)

      {

      	// TODO: probably also test returning -1 from this when things break?

      	return 0;

      }

      int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size)

      {

        Augie Fackler
    
xdiff: don't attempt to use fuzzer inputs larger than 100k...

              r41175
            
      	// Don't allow fuzzer inputs larger than 100k, since we'll just bog

      	// down and not accomplish much.

      	if (Size > 100000) {

      		return 0;

      	}

        Augie Fackler
    
fuzz: migrate xdiff fuzzer to use FuzzedDataProvider...

              r44012
            
      	FuzzedDataProvider provider(Data, Size);

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

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

        Augie Fackler
    
fuzz: add a fuzzer for xdiff...

              r36697
            
      	mmfile_t a, b;

        Augie Fackler
    
fuzz: migrate xdiff fuzzer to use FuzzedDataProvider...

              r44012
            
      	a.ptr = (char *)left.c_str();

      	a.size = left.size();

      	b.ptr = (char *)right.c_str();

      	b.size = right.size();

        Augie Fackler
    
fuzz: add a fuzzer for xdiff...

              r36697
            
      	xpparam_t xpp = {

      	    XDF_INDENT_HEURISTIC, /* flags */

      	};

      	xdemitconf_t xecfg = {

      	    XDL_EMIT_BDIFFHUNK, /* flags */

      	    hunk_consumer,      /* hunk_consume_func */

      	};

      	xdemitcb_t ecb = {

      	    NULL, /* priv */

      	};

      	xdl_diff(&a, &b, &xpp, &xecfg, &ecb);

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

      }

      } // extern "C"

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Augie Fackler fuzz: add a fuzzer for xdiff...	r36697	/*
		* xdiff.cc - fuzzer harness for thirdparty/xdiff
		*
		* 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 "thirdparty/xdiff/xdiff.h"
		#include <inttypes.h>
		#include <stdlib.h>

Augie Fackler fuzz: use a more standard approach to allow local builds of fuzzers...	r44265	#include "FuzzedDataProvider.h"
Augie Fackler fuzz: extract some common utilities and use modern C++ idioms...	r38191
Augie Fackler fuzz: add a fuzzer for xdiff...	r36697	extern "C" {

Augie Fackler fuzz: always define LLVMFuzzerInitialize() even if we don't need it...	r44261	int LLVMFuzzerInitialize(int argc, char **argv)
		{
		return 0;
		}

Augie Fackler fuzz: add a fuzzer for xdiff...	r36697	int hunk_consumer(long a1, long a2, long b1, long b2, void *priv)
		{
		// TODO: probably also test returning -1 from this when things break?
		return 0;
		}

		int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size)
		{
Augie Fackler xdiff: don't attempt to use fuzzer inputs larger than 100k...	r41175	// Don't allow fuzzer inputs larger than 100k, since we'll just bog
		// down and not accomplish much.
		if (Size > 100000) {
		return 0;
		}
Augie Fackler fuzz: migrate xdiff fuzzer to use FuzzedDataProvider...	r44012	FuzzedDataProvider provider(Data, Size);
		std::string left = provider.ConsumeRandomLengthString(Size);
		std::string right = provider.ConsumeRemainingBytesAsString();
Augie Fackler fuzz: add a fuzzer for xdiff...	r36697	mmfile_t a, b;

Augie Fackler fuzz: migrate xdiff fuzzer to use FuzzedDataProvider...	r44012	a.ptr = (char *)left.c_str();
		a.size = left.size();
		b.ptr = (char *)right.c_str();
		b.size = right.size();
Augie Fackler fuzz: add a fuzzer for xdiff...	r36697	xpparam_t xpp = {
		XDF_INDENT_HEURISTIC, /* flags */
		};
		xdemitconf_t xecfg = {
		XDL_EMIT_BDIFFHUNK, /* flags */
		hunk_consumer, /* hunk_consume_func */
		};
		xdemitcb_t ecb = {
		NULL, /* priv */
		};
		xdl_diff(&a, &b, &xpp, &xecfg, &ecb);
		return 0; // Non-zero return values are reserved for future use.
		}

		} // extern "C"