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/**
* This fuzz target performs a lz4 streaming round-trip test
* (compress & decompress), compares the result with the original, and calls
* abort() on corruption.
*/
#include <stddef.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include "fuzz_helpers.h"
#define LZ4_STATIC_LINKING_ONLY
#include "lz4.h"
typedef struct {
char const* buf;
size_t size;
size_t pos;
} const_cursor_t;
typedef struct {
char* buf;
size_t size;
size_t pos;
} cursor_t;
typedef struct {
LZ4_stream_t* cstream;
LZ4_streamDecode_t* dstream;
const_cursor_t data;
cursor_t compressed;
cursor_t roundTrip;
uint32_t seed;
} state_t;
cursor_t cursor_create(size_t size)
{
cursor_t cursor;
cursor.buf = (char*)malloc(size);
cursor.size = size;
cursor.pos = 0;
FUZZ_ASSERT(cursor.buf);
return cursor;
}
void cursor_free(cursor_t cursor)
{
free(cursor.buf);
}
state_t state_create(char const* data, size_t size, uint32_t seed)
{
state_t state;
state.seed = seed;
state.data.buf = (char const*)data;
state.data.size = size;
state.data.pos = 0;
/* Extra margin because we are streaming. */
state.compressed = cursor_create(1024 + 2 * LZ4_compressBound(size));
state.roundTrip = cursor_create(size);
state.cstream = LZ4_createStream();
FUZZ_ASSERT(state.cstream);
state.dstream = LZ4_createStreamDecode();
FUZZ_ASSERT(state.dstream);
return state;
}
void state_free(state_t state)
{
cursor_free(state.compressed);
cursor_free(state.roundTrip);
LZ4_freeStream(state.cstream);
LZ4_freeStreamDecode(state.dstream);
}
static void state_reset(state_t* state, uint32_t seed)
{
LZ4_resetStream_fast(state->cstream);
LZ4_setStreamDecode(state->dstream, NULL, 0);
state->data.pos = 0;
state->compressed.pos = 0;
state->roundTrip.pos = 0;
state->seed = seed;
}
static void state_decompress(state_t* state, char const* src, int srcSize)
{
char* dst = state->roundTrip.buf + state->roundTrip.pos;
int const dstCapacity = state->roundTrip.size - state->roundTrip.pos;
int const dSize = LZ4_decompress_safe_continue(state->dstream, src, dst,
srcSize, dstCapacity);
FUZZ_ASSERT(dSize >= 0);
state->roundTrip.pos += dSize;
}
static void state_checkRoundTrip(state_t const* state)
{
char const* data = state->data.buf;
size_t const size = state->data.size;
FUZZ_ASSERT_MSG(size == state->roundTrip.pos, "Incorrect size!");
FUZZ_ASSERT_MSG(!memcmp(data, state->roundTrip.buf, size), "Corruption!");
}
/**
* Picks a dictionary size and trims the dictionary off of the data.
*/
static size_t state_trimDict(state_t* state)
{
/* 64 KB is the max dict size, allow slightly beyond that to test trim. */
uint32_t maxDictSize = MIN(70 * 1024, state->data.size);
size_t const dictSize = FUZZ_rand32(&state->seed, 0, maxDictSize);
FUZZ_ASSERT(state->compressed.pos == 0);
state->compressed.pos += dictSize;
return dictSize;
}
static void state_prefixRoundTrip(state_t* state)
{
while (state->data.pos != state->data.size) {
char const* src = state->data.buf + state->data.pos;
char* dst = state->compressed.buf + state->compressed.pos;
int const srcRemaining = state->data.size - state->data.pos;
int const srcSize = FUZZ_rand32(&state->seed, 0, srcRemaining);
int const dstCapacity = state->compressed.size - state->compressed.pos;
int const cSize = LZ4_compress_fast_continue(state->cstream, src, dst,
srcSize, dstCapacity, 0);
FUZZ_ASSERT(cSize > 0);
state->data.pos += srcSize;
state->compressed.pos += cSize;
state_decompress(state, dst, cSize);
}
}
static void state_extDictRoundTrip(state_t* state)
{
int i = 0;
cursor_t data2 = cursor_create(state->data.size);
memcpy(data2.buf, state->data.buf, state->data.size);
while (state->data.pos != state->data.size) {
char const* data = (i++ & 1) ? state->data.buf : data2.buf;
char const* src = data + state->data.pos;
char* dst = state->compressed.buf + state->compressed.pos;
int const srcRemaining = state->data.size - state->data.pos;
int const srcSize = FUZZ_rand32(&state->seed, 0, srcRemaining);
int const dstCapacity = state->compressed.size - state->compressed.pos;
int const cSize = LZ4_compress_fast_continue(state->cstream, src, dst,
srcSize, dstCapacity, 0);
FUZZ_ASSERT(cSize > 0);
state->data.pos += srcSize;
state->compressed.pos += cSize;
state_decompress(state, dst, cSize);
}
cursor_free(data2);
}
static void state_randomRoundTrip(state_t* state)
{
if (FUZZ_rand32(&state->seed, 0, 1)) {
state_prefixRoundTrip(state);
} else {
state_extDictRoundTrip(state);
}
}
static void state_loadDictRoundTrip(state_t* state)
{
char const* dict = state->compressed.buf;
size_t const dictSize = state_trimDict(state);
LZ4_loadDict(state->cstream, dict, dictSize);
LZ4_setStreamDecode(state->dstream, dict, dictSize);
state_randomRoundTrip(state);
}
static void state_attachDictRoundTrip(state_t* state)
{
char const* dict = state->compressed.buf;
size_t const dictSize = state_trimDict(state);
LZ4_stream_t* dictStream = LZ4_createStream();
LZ4_loadDict(dictStream, dict, dictSize);
LZ4_attach_dictionary(state->cstream, dictStream);
LZ4_setStreamDecode(state->dstream, dict, dictSize);
state_randomRoundTrip(state);
LZ4_freeStream(dictStream);
}
typedef void (*round_trip_t)(state_t* state);
round_trip_t roundTrips[] = {
&state_prefixRoundTrip,
&state_extDictRoundTrip,
&state_loadDictRoundTrip,
&state_attachDictRoundTrip,
};
int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size)
{
uint32_t seed = FUZZ_seed(&data, &size);
state_t state = state_create((char const*)data, size, seed);
const int n = sizeof(roundTrips) / sizeof(round_trip_t);
int i;
for (i = 0; i < n; ++i) {
roundTrips[i](&state);
state_checkRoundTrip(&state);
state_reset(&state, seed);
}
state_free(state);
return 0;
}
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