annotate contrib/fuzz/xdiff.cc @ 47170:6e0ee1810fbd

revlog: rename `versionflags` to header

The variable is named as such because it contains "version" information and
"flags" information. However you mostly needs to know the code to understand the
name which is not great. The fact that this is the very first four bytes in all
revlog seems more relevant, so we rename the variable "header".

Differential Revision: https://phab.mercurial-scm.org/D10596

/*
 * 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>

#include "FuzzedDataProvider.h"

extern "C" {

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

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)
{
	// Don't allow fuzzer inputs larger than 100k, since we'll just bog
	// down and not accomplish much.
	if (Size > 100000) {
		return 0;
	}
	FuzzedDataProvider provider(Data, Size);
	std::string left = provider.ConsumeRandomLengthString(Size);
	std::string right = provider.ConsumeRemainingBytesAsString();
	mmfile_t a, b;

	a.ptr = (char *)left.c_str();
	a.size = left.size();
	b.ptr = (char *)right.c_str();
	b.size = right.size();
	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"