contrib/fuzz/xdiff.cc

largefiles: automatically load largefiles extension when required (BC)

This is very similar to what we just did for LFS but for largefiles.
See recent commit messages for the rationale here.

Differential Revision: https://phab.mercurial-scm.org/D4713

/*
 * 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 "fuzzutil.h"

extern "C" {

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)
{
	auto maybe_inputs = SplitInputs(Data, Size);
	if (!maybe_inputs) {
		return 0;
	}
	auto inputs = std::move(maybe_inputs.value());
	mmfile_t a, b;

	a.ptr = inputs.left.get();
	a.size = inputs.left_size;
	b.ptr = inputs.right.get();
	b.size = inputs.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.
}

#ifdef HG_FUZZER_INCLUDE_MAIN
int main(int argc, char **argv)
{
	const char data[] = "asdf";
	return LLVMFuzzerTestOneInput((const uint8_t *)data, 4);
}
#endif

} // extern "C"