[Fuzz] Improve data generation #1723

Converting the rest of the tests to use the new data producer.

tests/fuzz/stream_decompress.c

@@ -19,6 +19,7 @@
 #include <stdio.h>
 #include "fuzz_helpers.h"
 #include "zstd.h"
+#include "fuzz_data_producer.h"
 
 static size_t const kBufSize = ZSTD_BLOCKSIZE_MAX;
 
@@ -26,22 +27,23 @@ static ZSTD_DStream *dstream = NULL;
 static void* buf = NULL;
 uint32_t seed;
 
-static ZSTD_outBuffer makeOutBuffer(void)
+static ZSTD_outBuffer makeOutBuffer(FUZZ_dataProducer_t *producer)
 {
   ZSTD_outBuffer buffer = { buf, 0, 0 };
 
-  buffer.size = (FUZZ_rand(&seed) % kBufSize) + 1;
+  buffer.size = (FUZZ_dataProducer_uint32(producer) % kBufSize) + 1;
   FUZZ_ASSERT(buffer.size <= kBufSize);
 
   return buffer;
 }
 
-static ZSTD_inBuffer makeInBuffer(const uint8_t **src, size_t *size)
+static ZSTD_inBuffer makeInBuffer(const uint8_t **src, size_t *size,
+                                  FUZZ_dataProducer_t *producer)
 {
   ZSTD_inBuffer buffer = { *src, 0, 0 };
 
   FUZZ_ASSERT(*size > 0);
-  buffer.size = (FUZZ_rand(&seed) % *size) + 1;
+  buffer.size = (FUZZ_dataProducer_uint32(producer) % *size) + 1;
   FUZZ_ASSERT(buffer.size <= *size);
   *src += buffer.size;
   *size -= buffer.size;
@@ -51,13 +53,17 @@ static ZSTD_inBuffer makeInBuffer(const uint8_t **src, size_t *size)
 
 int LLVMFuzzerTestOneInput(const uint8_t *src, size_t size)
 {
-    seed = FUZZ_seed(&src, &size);
+    /* Give a random portion of src data to the producer, to use for
+    parameter generation. The rest will be used for (de)compression */
+    FUZZ_dataProducer_t *producer = FUZZ_dataProducer_create(src, size);
+    size_t producerSliceSize = FUZZ_dataProducer_uint32Range(producer, 0, size);
+    size = FUZZ_dataProducer_contract(producer, producerSliceSize);
 
     /* Allocate all buffers and contexts if not already allocated */
     if (!buf) {
       buf = malloc(kBufSize);
-      FUZZ_ASSERT(buf);
-    }
+        FUZZ_ASSERT(buf);
+      }
 
     if (!dstream) {
         dstream = ZSTD_createDStream();
@@ -67,9 +73,9 @@ int LLVMFuzzerTestOneInput(const uint8_t *src, size_t size)
     }
 
     while (size > 0) {
-        ZSTD_inBuffer in = makeInBuffer(&src, &size);
+        ZSTD_inBuffer in = makeInBuffer(&src, &size, producer);
         while (in.pos != in.size) {
-            ZSTD_outBuffer out = makeOutBuffer();
+            ZSTD_outBuffer out = makeOutBuffer(producer);
             size_t const rc = ZSTD_decompressStream(dstream, &out, &in);
             if (ZSTD_isError(rc)) goto error;
         }
@@ -79,5 +85,6 @@ error:
 #ifndef STATEFUL_FUZZING
     ZSTD_freeDStream(dstream); dstream = NULL;
 #endif
+    FUZZ_dataProducer_free(producer);
     return 0;
 }