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

This will make it easier to test our fuzzers outside oss-fuzz.

Differential Revision: https://phab.mercurial-scm.org/D7560

contrib/fuzz/bdiff.cc

@@ -1,42 +1,47 b''
 /*
  * 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 <fuzzer/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.
 }
 
 #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"

contrib/fuzz/mpatch.cc

@@ -1,122 +1,127 b''
 /*
  * 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;
 }
 
 #ifdef HG_FUZZER_INCLUDE_MAIN
 int main(int argc, char **argv)
 {
 	// One text, one patch.
 	const char data[] = "\x02\x00\0x1\x00\x0d"
 	                    // base text
 	                    "a"
 	                    // binary delta that will append a single b
 	                    "\x00\x00\x00\x01\x00\x00\x00\x01\x00\x00\x00\x01b";
 	return LLVMFuzzerTestOneInput((const uint8_t *)data, 19);
 }
 #endif
 
 } // extern "C"

contrib/fuzz/xdiff.cc

@@ -1,61 +1,66 b''
 /*
  * 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 <fuzzer/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.
 }
 
 #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"