view contrib/fuzz/mpatch.cc @ 50366:a445194f0a4d stable

backup: fix issue when the backup end up in a different directory

Because of store encoding, we might end up with the backup in a different
directory than the initial copy (for example if the backup path make it cross
the 120 char limit).

This can create crash, especially since 6.4 where backup are used during revlog
split.

Making sure the directory exists fixes these crash We added a test covering this
case.

Strictly speaking, this has always been broken, however the new code in 6.4
triggers it more easily.

/*
 * mpatch.cc - fuzzer harness for mpatch.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 <iostream>
#include <memory>
#include <stdint.h>
#include <stdlib.h>
#include <vector>

#include "fuzzutil.h"

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

// To avoid having too many OOMs from the fuzzer infrastructure, we'll
// skip patch application if the resulting fulltext would be bigger
// than 10MiB.
#define MAX_OUTPUT_SIZE 10485760

extern "C" {
#include "bitmanipulation.h"
#include "mpatch.h"

struct mpatchbin {
	std::unique_ptr<char[]> data;
	size_t len;
};

static mpatch_flist *getitem(void *vbins, ssize_t pos)
{
	std::vector<mpatchbin> *bins = (std::vector<mpatchbin> *)vbins;
	const mpatchbin &bin = bins->at(pos + 1);
	struct mpatch_flist *res;
	LOG(2) << "mpatch_decode " << bin.len << std::endl;
	if (mpatch_decode(bin.data.get(), bin.len, &res) < 0)
		return NULL;
	return res;
}

// input format:
// u8 number of inputs
// one u16 for each input, its length
// the inputs
int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size)
{
	if (!Size) {
		return 0;
	}
	// First byte of data is how many texts we expect, first text
	// being the base the rest being the deltas.
	ssize_t numtexts = Data[0];
	if (numtexts < 2) {
		// No point if we don't have at least a base text and a delta...
		return 0;
	}
	// Each text will be described by a byte for how long it
	// should be, so give up if we don't have enough.
	if ((Size - 1) < (numtexts * 2)) {
		return 0;
	}
	size_t consumed = 1 + (numtexts * 2);
	LOG(2) << "input contains " << Size << std::endl;
	LOG(2) << numtexts << " texts, consuming " << consumed << std::endl;
	std::vector<mpatchbin> bins;
	bins.reserve(numtexts);
	for (int i = 0; i < numtexts; ++i) {
		mpatchbin bin;
		size_t nthsize = getbeuint16((char *)Data + 1 + (2 * i));
		LOG(2) << "text " << i << " is " << nthsize << std::endl;
		char *start = (char *)Data + consumed;
		consumed += nthsize;
		if (consumed > Size) {
			LOG(2) << "ran out of data, consumed " << consumed
			       << " of " << Size << std::endl;
			return 0;
		}
		bin.len = nthsize;
		bin.data.reset(new char[nthsize]);
		memcpy(bin.data.get(), start, nthsize);
		bins.push_back(std::move(bin));
	}
	LOG(2) << "mpatch_flist" << std::endl;
	struct mpatch_flist *patch =
	    mpatch_fold(&bins, getitem, 0, numtexts - 1);
	if (!patch) {
		return 0;
	}
	LOG(2) << "mpatch_calcsize" << std::endl;
	ssize_t outlen = mpatch_calcsize(bins[0].len, patch);
	LOG(2) << "outlen " << outlen << std::endl;
	if (outlen < 0 || outlen > MAX_OUTPUT_SIZE) {
		goto cleanup;
	}
	{
		char *dest = (char *)malloc(outlen);
		LOG(2) << "expecting " << outlen << " total bytes at "
		       << (void *)dest << std::endl;
		mpatch_apply(dest, bins[0].data.get(), bins[0].len, patch);
		free(dest);
		LOG(1) << "applied a complete patch" << std::endl;
	}
cleanup:
	mpatch_lfree(patch);
	return 0;
}

} // extern "C"