Adding upstream version 16.2.11+ds.upstream/16.2.11+dsupstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

25 files changed, 3126 insertions, 0 deletions

diff --git a/src/zstd/tests/fuzz/.gitignore b/src/zstd/tests/fuzz/.gitignore
new file mode 100644
index 000000000..b6fc6e506
--- /dev/null
+++ b/src/zstd/tests/fuzz/.gitignore
@@ -0,0 +1,20 @@
+# test artefacts
+corpora
+block_decompress
+block_round_trip
+dictionary_decompress
+dictionary_loader
+dictionary_round_trip
+dictionary_stream_round_trip
+raw_dictionary_round_trip
+simple_compress
+simple_decompress
+simple_round_trip
+stream_decompress
+stream_round_trip
+zstd_frame_info
+fuzz-*.log
+
+# misc
+trace
+tmp*
diff --git a/src/zstd/tests/fuzz/Makefile b/src/zstd/tests/fuzz/Makefile
new file mode 100644
index 000000000..1af3dc734
--- /dev/null
+++ b/src/zstd/tests/fuzz/Makefile
@@ -0,0 +1,212 @@
+# ################################################################
+# Copyright (c) 2016-2020, Facebook, Inc.
+# All rights reserved.
+#
+# This source code is licensed under both the BSD-style license (found in the
+# LICENSE file in the root directory of this source tree) and the GPLv2 (found
+# in the COPYING file in the root directory of this source tree).
+# You may select, at your option, one of the above-listed licenses.
+# ################################################################
+
+# Optionally user defined flags
+CFLAGS ?= -O3
+CXXFLAGS ?= -O3
+CPPFLAGS ?=
+LDFLAGS ?=
+ARFLAGS ?=
+LIB_FUZZING_ENGINE ?= libregression.a
+PYTHON ?= python
+ifeq ($(shell uname), Darwin)
+	DOWNLOAD?=curl -L -o
+else
+	DOWNLOAD?=wget -O
+endif
+CORPORA_URL_PREFIX:=https://github.com/facebook/zstd/releases/download/fuzz-corpora/
+
+ZSTDDIR = ../../lib
+PRGDIR = ../../programs
+
+FUZZ_CPPFLAGS := -I$(ZSTDDIR) -I$(ZSTDDIR)/common -I$(ZSTDDIR)/compress \
+	-I$(ZSTDDIR)/dictBuilder -I$(ZSTDDIR)/deprecated -I$(ZSTDDIR)/legacy \
+	-I$(PRGDIR) -DZSTD_MULTITHREAD -DZSTD_LEGACY_SUPPORT=1 $(CPPFLAGS)
+FUZZ_EXTRA_FLAGS := -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow \
+	-Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement \
+	-Wstrict-prototypes -Wundef \
+	-Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings \
+	-Wredundant-decls \
+	-g -fno-omit-frame-pointer
+FUZZ_CFLAGS := $(FUZZ_EXTRA_FLAGS) $(CFLAGS)
+FUZZ_CXXFLAGS := $(FUZZ_EXTRA_FLAGS) -std=c++11 $(CXXFLAGS)
+FUZZ_LDFLAGS := -pthread $(LDFLAGS)
+FUZZ_ARFLAGS := $(ARFLAGS)
+FUZZ_TARGET_FLAGS = $(FUZZ_CPPFLAGS) $(FUZZ_CXXFLAGS) $(FUZZ_LDFLAGS)
+
+FUZZ_ROUND_TRIP_FLAGS := -DFUZZING_ASSERT_VALID_SEQUENCE
+
+FUZZ_HEADERS := fuzz_helpers.h fuzz.h zstd_helpers.h fuzz_data_producer.h
+FUZZ_SRC := $(PRGDIR)/util.c ./fuzz_helpers.c ./zstd_helpers.c ./fuzz_data_producer.c
+
+ZSTDCOMMON_SRC := $(ZSTDDIR)/common/*.c
+ZSTDCOMP_SRC   := $(ZSTDDIR)/compress/*.c
+ZSTDDECOMP_SRC := $(ZSTDDIR)/decompress/*.c
+ZSTDDICT_SRC := $(ZSTDDIR)/dictBuilder/*.c
+ZSTDLEGACY_SRC := $(ZSTDDIR)/legacy/*.c
+FUZZ_SRC       := \
+	$(FUZZ_SRC) \
+	$(ZSTDDECOMP_SRC) \
+	$(ZSTDCOMMON_SRC) \
+	$(ZSTDCOMP_SRC) \
+	$(ZSTDDICT_SRC) \
+	$(ZSTDLEGACY_SRC)
+FUZZ_SRC := $(wildcard $(FUZZ_SRC))
+
+FUZZ_D_OBJ1 := $(subst $(ZSTDDIR)/common/,d_lib_common_,$(FUZZ_SRC))
+FUZZ_D_OBJ2 := $(subst $(ZSTDDIR)/compress/,d_lib_compress_,$(FUZZ_D_OBJ1))
+FUZZ_D_OBJ3 := $(subst $(ZSTDDIR)/decompress/,d_lib_decompress_,$(FUZZ_D_OBJ2))
+FUZZ_D_OBJ4 := $(subst $(ZSTDDIR)/dictBuilder/,d_lib_dictBuilder_,$(FUZZ_D_OBJ3))
+FUZZ_D_OBJ5 := $(subst $(ZSTDDIR)/legacy/,d_lib_legacy_,$(FUZZ_D_OBJ4))
+FUZZ_D_OBJ6 := $(subst $(PRGDIR)/,d_prg_,$(FUZZ_D_OBJ5))
+FUZZ_D_OBJ7 := $(subst $\./,d_fuzz_,$(FUZZ_D_OBJ6))
+FUZZ_DECOMPRESS_OBJ := $(FUZZ_D_OBJ7:.c=.o)
+
+FUZZ_RT_OBJ1 := $(subst $(ZSTDDIR)/common/,rt_lib_common_,$(FUZZ_SRC))
+FUZZ_RT_OBJ2 := $(subst $(ZSTDDIR)/compress/,rt_lib_compress_,$(FUZZ_RT_OBJ1))
+FUZZ_RT_OBJ3 := $(subst $(ZSTDDIR)/decompress/,rt_lib_decompress_,$(FUZZ_RT_OBJ2))
+FUZZ_RT_OBJ4 := $(subst $(ZSTDDIR)/dictBuilder/,rt_lib_dictBuilder_,$(FUZZ_RT_OBJ3))
+FUZZ_RT_OBJ5 := $(subst $(ZSTDDIR)/legacy/,rt_lib_legacy_,$(FUZZ_RT_OBJ4))
+FUZZ_RT_OBJ6 := $(subst $(PRGDIR)/,rt_prg_,$(FUZZ_RT_OBJ5))
+FUZZ_RT_OBJ7 := $(subst $\./,rt_fuzz_,$(FUZZ_RT_OBJ6))
+FUZZ_ROUND_TRIP_OBJ := $(FUZZ_RT_OBJ7:.c=.o)
+
+.PHONY: default all clean cleanall
+
+default: all
+
+FUZZ_TARGETS :=       \
+	simple_round_trip \
+	stream_round_trip \
+	block_round_trip  \
+	simple_decompress \
+	stream_decompress \
+	block_decompress  \
+	dictionary_round_trip \
+	dictionary_decompress \
+	zstd_frame_info \
+	simple_compress \
+	dictionary_loader \
+	raw_dictionary_round_trip \
+	dictionary_stream_round_trip
+
+all: $(FUZZ_TARGETS)
+
+rt_lib_common_%.o: $(ZSTDDIR)/common/%.c
+	$(CC) $(FUZZ_CPPFLAGS) $(FUZZ_CFLAGS) $(FUZZ_ROUND_TRIP_FLAGS) $< -c -o $@
+
+rt_lib_compress_%.o: $(ZSTDDIR)/compress/%.c
+	$(CC) $(FUZZ_CPPFLAGS) $(FUZZ_CFLAGS) $(FUZZ_ROUND_TRIP_FLAGS) $< -c -o $@
+
+rt_lib_decompress_%.o: $(ZSTDDIR)/decompress/%.c
+	$(CC) $(FUZZ_CPPFLAGS) $(FUZZ_CFLAGS) $(FUZZ_ROUND_TRIP_FLAGS) $< -c -o $@
+
+rt_lib_dictBuilder_%.o: $(ZSTDDIR)/dictBuilder/%.c
+	$(CC) $(FUZZ_CPPFLAGS) $(FUZZ_CFLAGS) $(FUZZ_ROUND_TRIP_FLAGS) $< -c -o $@
+
+rt_lib_legacy_%.o: $(ZSTDDIR)/legacy/%.c
+	$(CC) $(FUZZ_CPPFLAGS) $(FUZZ_CFLAGS) $(FUZZ_ROUND_TRIP_FLAGS) $< -c -o $@
+
+rt_prg_%.o: $(PRGDIR)/%.c
+	$(CC) $(FUZZ_CPPFLAGS) $(FUZZ_CFLAGS) $(FUZZ_ROUND_TRIP_FLAGS) $< -c -o $@
+
+rt_fuzz_%.o: %.c
+	$(CC) $(FUZZ_CPPFLAGS) $(FUZZ_CFLAGS) $(FUZZ_ROUND_TRIP_FLAGS) $< -c -o $@
+
+d_lib_common_%.o: $(ZSTDDIR)/common/%.c
+	$(CC) $(FUZZ_CPPFLAGS) $(FUZZ_CFLAGS) $< -c -o $@
+
+d_lib_compress_%.o: $(ZSTDDIR)/compress/%.c
+	$(CC) $(FUZZ_CPPFLAGS) $(FUZZ_CFLAGS) $< -c -o $@
+
+d_lib_decompress_%.o: $(ZSTDDIR)/decompress/%.c
+	$(CC) $(FUZZ_CPPFLAGS) $(FUZZ_CFLAGS) $< -c -o $@
+
+d_lib_dictBuilder_%.o: $(ZSTDDIR)/dictBuilder/%.c
+	$(CC) $(FUZZ_CPPFLAGS) $(FUZZ_CFLAGS) $< -c -o $@
+
+d_lib_legacy_%.o: $(ZSTDDIR)/legacy/%.c
+	$(CC) $(FUZZ_CPPFLAGS) $(FUZZ_CFLAGS) $< -c -o $@
+
+d_prg_%.o: $(PRGDIR)/%.c
+	$(CC) $(FUZZ_CPPFLAGS) $(FUZZ_CFLAGS) $< -c -o $@
+
+d_fuzz_%.o: %.c
+	$(CC) $(FUZZ_CPPFLAGS) $(FUZZ_CFLAGS) $< -c -o $@
+
+simple_round_trip: $(FUZZ_HEADERS) $(FUZZ_ROUND_TRIP_OBJ) rt_fuzz_simple_round_trip.o
+	$(CXX) $(FUZZ_TARGET_FLAGS) $(FUZZ_ROUND_TRIP_OBJ) rt_fuzz_simple_round_trip.o $(LIB_FUZZING_ENGINE) -o $@
+
+stream_round_trip: $(FUZZ_HEADERS) $(FUZZ_ROUND_TRIP_OBJ) rt_fuzz_stream_round_trip.o
+	$(CXX) $(FUZZ_TARGET_FLAGS) $(FUZZ_ROUND_TRIP_OBJ) rt_fuzz_stream_round_trip.o $(LIB_FUZZING_ENGINE) -o $@
+
+block_round_trip: $(FUZZ_HEADERS) $(FUZZ_ROUND_TRIP_OBJ) rt_fuzz_block_round_trip.o
+	$(CXX) $(FUZZ_TARGET_FLAGS) $(FUZZ_ROUND_TRIP_OBJ) rt_fuzz_block_round_trip.o $(LIB_FUZZING_ENGINE) -o $@
+
+simple_decompress: $(FUZZ_HEADERS) $(FUZZ_DECOMPRESS_OBJ) d_fuzz_simple_decompress.o
+	$(CXX) $(FUZZ_TARGET_FLAGS) $(FUZZ_DECOMPRESS_OBJ) d_fuzz_simple_decompress.o $(LIB_FUZZING_ENGINE) -o $@
+
+stream_decompress: $(FUZZ_HEADERS) $(FUZZ_DECOMPRESS_OBJ) d_fuzz_stream_decompress.o
+	$(CXX) $(FUZZ_TARGET_FLAGS) $(FUZZ_DECOMPRESS_OBJ) d_fuzz_stream_decompress.o $(LIB_FUZZING_ENGINE) -o $@
+
+block_decompress: $(FUZZ_HEADERS) $(FUZZ_DECOMPRESS_OBJ) d_fuzz_block_decompress.o
+	$(CXX) $(FUZZ_TARGET_FLAGS) $(FUZZ_DECOMPRESS_OBJ) d_fuzz_block_decompress.o $(LIB_FUZZING_ENGINE) -o $@
+
+dictionary_round_trip: $(FUZZ_HEADERS) $(FUZZ_ROUND_TRIP_OBJ) rt_fuzz_dictionary_round_trip.o
+	$(CXX) $(FUZZ_TARGET_FLAGS) $(FUZZ_ROUND_TRIP_OBJ) rt_fuzz_dictionary_round_trip.o $(LIB_FUZZING_ENGINE) -o $@
+
+raw_dictionary_round_trip: $(FUZZ_HEADERS) $(FUZZ_ROUND_TRIP_OBJ) rt_fuzz_raw_dictionary_round_trip.o
+	$(CXX) $(FUZZ_TARGET_FLAGS) $(FUZZ_ROUND_TRIP_OBJ) rt_fuzz_raw_dictionary_round_trip.o $(LIB_FUZZING_ENGINE) -o $@
+
+dictionary_stream_round_trip: $(FUZZ_HEADERS) $(FUZZ_ROUND_TRIP_OBJ) rt_fuzz_dictionary_stream_round_trip.o
+	$(CXX) $(FUZZ_TARGET_FLAGS) $(FUZZ_ROUND_TRIP_OBJ) rt_fuzz_dictionary_stream_round_trip.o $(LIB_FUZZING_ENGINE) -o $@
+
+dictionary_decompress: $(FUZZ_HEADERS) $(FUZZ_DECOMPRESS_OBJ) d_fuzz_dictionary_decompress.o
+	$(CXX) $(FUZZ_TARGET_FLAGS) $(FUZZ_DECOMPRESS_OBJ) d_fuzz_dictionary_decompress.o $(LIB_FUZZING_ENGINE) -o $@
+
+simple_compress: $(FUZZ_HEADERS) $(FUZZ_ROUND_TRIP_OBJ) rt_fuzz_simple_compress.o
+	$(CXX) $(FUZZ_TARGET_FLAGS) $(FUZZ_ROUND_TRIP_OBJ) rt_fuzz_simple_compress.o $(LIB_FUZZING_ENGINE) -o $@
+
+zstd_frame_info: $(FUZZ_HEADERS) $(FUZZ_DECOMPRESS_OBJ) d_fuzz_zstd_frame_info.o
+	$(CXX) $(FUZZ_TARGET_FLAGS) $(FUZZ_DECOMPRESS_OBJ) d_fuzz_zstd_frame_info.o $(LIB_FUZZING_ENGINE) -o $@
+
+dictionary_loader: $(FUZZ_HEADERS) $(FUZZ_ROUND_TRIP_OBJ) rt_fuzz_dictionary_loader.o
+	$(CXX) $(FUZZ_TARGET_FLAGS) $(FUZZ_ROUND_TRIP_OBJ) rt_fuzz_dictionary_loader.o $(LIB_FUZZING_ENGINE) -o $@
+
+libregression.a: $(FUZZ_HEADERS) $(PRGDIR)/util.h $(PRGDIR)/util.c d_fuzz_regression_driver.o
+	$(AR) $(FUZZ_ARFLAGS) $@ d_fuzz_regression_driver.o
+
+corpora/%_seed_corpus.zip:
+	@mkdir -p corpora
+	$(DOWNLOAD) $@ $(CORPORA_URL_PREFIX)$*_seed_corpus.zip
+
+corpora/%: corpora/%_seed_corpus.zip
+	unzip -q $^ -d $@
+
+.PHONY: corpora
+corpora: $(patsubst %,corpora/%,$(FUZZ_TARGETS))
+
+.PHONY: seedcorpora
+seedcorpora: $(patsubst %,corpora/%_seed_corpus.zip,$(FUZZ_TARGETS))
+
+regressiontest: corpora
+	CC="$(CC)" CXX="$(CXX)" CFLAGS="$(CFLAGS)" CXXFLAGS="$(CXXFLAGS)" LDFLAGS="$(LDFLAGS)" $(PYTHON) ./fuzz.py build all
+	$(PYTHON) ./fuzz.py regression all
+
+clean:
+	@$(RM) *.a *.o
+	@$(RM) simple_round_trip stream_round_trip simple_decompress \
+           stream_decompress block_decompress block_round_trip \
+           simple_compress dictionary_round_trip dictionary_decompress \
+           zstd_frame_info
+
+cleanall:
+	@$(RM) -r Fuzzer
+	@$(RM) -r corpora
diff --git a/src/zstd/tests/fuzz/README.md b/src/zstd/tests/fuzz/README.md
new file mode 100644
index 000000000..71afa4063
--- /dev/null
+++ b/src/zstd/tests/fuzz/README.md
@@ -0,0 +1,101 @@
+# Fuzzing
+
+Each fuzzing target can be built with multiple engines.
+Zstd provides a fuzz corpus for each target that can be downloaded with
+the command:
+
+```
+make corpora
+```
+
+It will download each corpus into `./corpora/TARGET`.
+
+## fuzz.py
+
+`fuzz.py` is a helper script for building and running fuzzers.
+Run `./fuzz.py -h` for the commands and run `./fuzz.py COMMAND -h` for
+command specific help.
+
+### Generating Data
+
+`fuzz.py` provides a utility to generate seed data for each fuzzer.
+
+```
+make -C ../tests decodecorpus
+./fuzz.py gen TARGET
+```
+
+By default it outputs 100 samples, each at most 8KB into `corpora/TARGET-seed`,
+but that can be configured with the `--number`, `--max-size-log` and `--seed`
+flags.
+
+### Build
+It respects the usual build environment variables `CC`, `CFLAGS`, etc.
+The environment variables can be overridden with the corresponding flags
+`--cc`, `--cflags`, etc.
+The specific fuzzing engine is selected with `LIB_FUZZING_ENGINE` or
+`--lib-fuzzing-engine`, the default is `libregression.a`.
+Alternatively, you can use Clang's built in fuzzing engine with
+`--enable-fuzzer`.
+It has flags that can easily set up sanitizers `--enable-{a,ub,m}san`, and
+coverage instrumentation `--enable-coverage`.
+It sets sane defaults which can be overridden with flags `--debug`,
+`--enable-ubsan-pointer-overflow`, etc.
+Run `./fuzz.py build -h` for help.
+
+### Running Fuzzers
+
+`./fuzz.py` can run `libfuzzer`, `afl`, and `regression` tests.
+See the help of the relevant command for options.
+Flags not parsed by `fuzz.py` are passed to the fuzzing engine.
+The command used to run the fuzzer is printed for debugging.
+
+## LibFuzzer
+
+```
+# Build the fuzz targets
+./fuzz.py build all --enable-fuzzer --enable-asan --enable-ubsan --cc clang --cxx clang++
+# OR equivalently
+CC=clang CXX=clang++ ./fuzz.py build all --enable-fuzzer --enable-asan --enable-ubsan
+# Run the fuzzer
+./fuzz.py libfuzzer TARGET <libfuzzer args like -jobs=4>
+```
+
+where `TARGET` could be `simple_decompress`, `stream_round_trip`, etc.
+
+### MSAN
+
+Fuzzing with `libFuzzer` and `MSAN` is as easy as:
+
+```
+CC=clang CXX=clang++ ./fuzz.py build all --enable-fuzzer --enable-msan
+./fuzz.py libfuzzer TARGET <libfuzzer args>
+```
+
+`fuzz.py` respects the environment variables / flags `MSAN_EXTRA_CPPFLAGS`,
+`MSAN_EXTRA_CFLAGS`, `MSAN_EXTRA_CXXFLAGS`, `MSAN_EXTRA_LDFLAGS` to easily pass
+the extra parameters only for MSAN.
+
+## AFL
+
+The default `LIB_FUZZING_ENGINE` is `libregression.a`, which produces a binary
+that AFL can use.
+
+```
+# Build the fuzz targets
+CC=afl-clang CXX=afl-clang++ ./fuzz.py build all --enable-asan --enable-ubsan
+# Run the fuzzer without a memory limit because of ASAN
+./fuzz.py afl TARGET -m none
+```
+
+## Regression Testing
+
+The regression test supports the `all` target to run all the fuzzers in one
+command.
+
+```
+CC=clang CXX=clang++ ./fuzz.py build all --enable-asan --enable-ubsan
+./fuzz.py regression all
+CC=clang CXX=clang++ ./fuzz.py build all --enable-msan
+./fuzz.py regression all
+```
diff --git a/src/zstd/tests/fuzz/block_decompress.c b/src/zstd/tests/fuzz/block_decompress.c
new file mode 100644
index 000000000..64d70f005
--- /dev/null
+++ b/src/zstd/tests/fuzz/block_decompress.c
@@ -0,0 +1,49 @@
+/**
+ * Copyright (c) 2016-2020, Yann Collet, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under both the BSD-style license (found in the
+ * LICENSE file in the root directory of this source tree) and the GPLv2 (found
+ * in the COPYING file in the root directory of this source tree).
+ * You may select, at your option, one of the above-listed licenses.
+ */
+
+/**
+ * This fuzz target attempts to decompress the fuzzed data with the simple
+ * decompression function to ensure the decompressor never crashes.
+ */
+
+#define ZSTD_STATIC_LINKING_ONLY
+
+#include <stddef.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include "fuzz_helpers.h"
+#include "zstd.h"
+
+static ZSTD_DCtx *dctx = NULL;
+static void* rBuf = NULL;
+static size_t bufSize = 0;
+
+int LLVMFuzzerTestOneInput(const uint8_t *src, size_t size)
+{
+    size_t const neededBufSize = ZSTD_BLOCKSIZE_MAX;
+
+    /* Allocate all buffers and contexts if not already allocated */
+    if (neededBufSize > bufSize) {
+        free(rBuf);
+        rBuf = FUZZ_malloc(neededBufSize);
+        bufSize = neededBufSize;
+    }
+    if (!dctx) {
+        dctx = ZSTD_createDCtx();
+        FUZZ_ASSERT(dctx);
+    }
+    ZSTD_decompressBegin(dctx);
+    ZSTD_decompressBlock(dctx, rBuf, neededBufSize, src, size);
+
+#ifndef STATEFUL_FUZZING
+    ZSTD_freeDCtx(dctx); dctx = NULL;
+#endif
+    return 0;
+}
diff --git a/src/zstd/tests/fuzz/block_round_trip.c b/src/zstd/tests/fuzz/block_round_trip.c
new file mode 100644
index 000000000..097fc01b8
--- /dev/null
+++ b/src/zstd/tests/fuzz/block_round_trip.c
@@ -0,0 +1,99 @@
+/**
+ * Copyright (c) 2016-2020, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under both the BSD-style license (found in the
+ * LICENSE file in the root directory of this source tree) and the GPLv2 (found
+ * in the COPYING file in the root directory of this source tree).
+ * You may select, at your option, one of the above-listed licenses.
+ */
+
+/**
+ * This fuzz target performs a zstd round-trip test (compress & decompress),
+ * compares the result with the original, and calls abort() on corruption.
+ */
+
+#define ZSTD_STATIC_LINKING_ONLY
+
+#include <stddef.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include "fuzz_helpers.h"
+#include "zstd.h"
+#include "zstd_helpers.h"
+#include "fuzz_data_producer.h"
+
+static ZSTD_CCtx *cctx = NULL;
+static ZSTD_DCtx *dctx = NULL;
+static void* cBuf = NULL;
+static void* rBuf = NULL;
+static size_t bufSize = 0;
+
+static size_t roundTripTest(void *result, size_t resultCapacity,
+                            void *compressed, size_t compressedCapacity,
+                            const void *src, size_t srcSize,
+                            int cLevel)
+{
+    ZSTD_parameters const params = ZSTD_getParams(cLevel, srcSize, 0);
+    size_t ret = ZSTD_compressBegin_advanced(cctx, NULL, 0, params, srcSize);
+    FUZZ_ZASSERT(ret);
+
+    ret = ZSTD_compressBlock(cctx, compressed, compressedCapacity, src, srcSize);
+    FUZZ_ZASSERT(ret);
+    if (ret == 0) {
+        FUZZ_ASSERT(resultCapacity >= srcSize);
+        if (srcSize > 0) {
+            memcpy(result, src, srcSize);
+        }
+        return srcSize;
+    }
+    ZSTD_decompressBegin(dctx);
+    return ZSTD_decompressBlock(dctx, result, resultCapacity, compressed, ret);
+}
+
+int LLVMFuzzerTestOneInput(const uint8_t *src, size_t 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 = FUZZ_dataProducer_reserveDataPrefix(producer);
+
+    int const cLevel = FUZZ_dataProducer_int32Range(producer, kMinClevel, kMaxClevel);
+
+    size_t neededBufSize = size;
+    if (size > ZSTD_BLOCKSIZE_MAX)
+        size = ZSTD_BLOCKSIZE_MAX;
+
+    /* Allocate all buffers and contexts if not already allocated */
+    if (neededBufSize > bufSize || !cBuf || !rBuf) {
+        free(cBuf);
+        free(rBuf);
+        cBuf = FUZZ_malloc(neededBufSize);
+        rBuf = FUZZ_malloc(neededBufSize);
+        bufSize = neededBufSize;
+    }
+    if (!cctx) {
+        cctx = ZSTD_createCCtx();
+        FUZZ_ASSERT(cctx);
+    }
+    if (!dctx) {
+        dctx = ZSTD_createDCtx();
+        FUZZ_ASSERT(dctx);
+    }
+
+    {
+        size_t const result =
+            roundTripTest(rBuf, neededBufSize, cBuf, neededBufSize, src, size,
+              cLevel);
+        FUZZ_ZASSERT(result);
+        FUZZ_ASSERT_MSG(result == size, "Incorrect regenerated size");
+        FUZZ_ASSERT_MSG(!FUZZ_memcmp(src, rBuf, size), "Corruption!");
+    }
+    FUZZ_dataProducer_free(producer);
+#ifndef STATEFUL_FUZZING
+    ZSTD_freeCCtx(cctx); cctx = NULL;
+    ZSTD_freeDCtx(dctx); dctx = NULL;
+#endif
+    return 0;
+}
diff --git a/src/zstd/tests/fuzz/dictionary_decompress.c b/src/zstd/tests/fuzz/dictionary_decompress.c
new file mode 100644
index 000000000..9944baa15
--- /dev/null
+++ b/src/zstd/tests/fuzz/dictionary_decompress.c
@@ -0,0 +1,73 @@
+/*
+ * Copyright (c) 2016-2020, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under both the BSD-style license (found in the
+ * LICENSE file in the root directory of this source tree) and the GPLv2 (found
+ * in the COPYING file in the root directory of this source tree).
+ * You may select, at your option, one of the above-listed licenses.
+ */
+
+/**
+ * This fuzz target attempts to decompress the fuzzed data with the dictionary
+ * decompression function to ensure the decompressor never crashes. It does not
+ * fuzz the dictionary.
+ */
+
+#include <stddef.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include "fuzz_helpers.h"
+#include "zstd_helpers.h"
+#include "fuzz_data_producer.h"
+
+static ZSTD_DCtx *dctx = NULL;
+
+int LLVMFuzzerTestOneInput(const uint8_t *src, size_t 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 = FUZZ_dataProducer_reserveDataPrefix(producer);
+
+    FUZZ_dict_t dict;
+    ZSTD_DDict* ddict = NULL;
+
+    if (!dctx) {
+        dctx = ZSTD_createDCtx();
+        FUZZ_ASSERT(dctx);
+    }
+    dict = FUZZ_train(src, size, producer);
+    if (FUZZ_dataProducer_uint32Range(producer, 0, 1) == 0) {
+        ddict = ZSTD_createDDict(dict.buff, dict.size);
+        FUZZ_ASSERT(ddict);
+    } else {
+        if (FUZZ_dataProducer_uint32Range(producer, 0, 1) == 0)
+            FUZZ_ZASSERT(ZSTD_DCtx_loadDictionary_advanced(
+                dctx, dict.buff, dict.size,
+                (ZSTD_dictLoadMethod_e)FUZZ_dataProducer_uint32Range(producer, 0, 1),
+                (ZSTD_dictContentType_e)FUZZ_dataProducer_uint32Range(producer, 0, 2)));
+        else
+            FUZZ_ZASSERT(ZSTD_DCtx_refPrefix_advanced(
+                dctx, dict.buff, dict.size,
+                (ZSTD_dictContentType_e)FUZZ_dataProducer_uint32Range(producer, 0, 2)));
+    }
+
+    {
+        size_t const bufSize = FUZZ_dataProducer_uint32Range(producer, 0, 10 * size);
+        void* rBuf = FUZZ_malloc(bufSize);
+        if (ddict) {
+            ZSTD_decompress_usingDDict(dctx, rBuf, bufSize, src, size, ddict);
+        } else {
+            ZSTD_decompressDCtx(dctx, rBuf, bufSize, src, size);
+        }
+        free(rBuf);
+    }
+    free(dict.buff);
+    FUZZ_dataProducer_free(producer);
+    ZSTD_freeDDict(ddict);
+#ifndef STATEFUL_FUZZING
+    ZSTD_freeDCtx(dctx); dctx = NULL;
+#endif
+    return 0;
+}
diff --git a/src/zstd/tests/fuzz/dictionary_loader.c b/src/zstd/tests/fuzz/dictionary_loader.c
new file mode 100644
index 000000000..f1fdf4da9
--- /dev/null
+++ b/src/zstd/tests/fuzz/dictionary_loader.c
@@ -0,0 +1,103 @@
+/*
+ * Copyright (c) 2016-2020, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under both the BSD-style license (found in the
+ * LICENSE file in the root directory of this source tree) and the GPLv2 (found
+ * in the COPYING file in the root directory of this source tree).
+ * You may select, at your option, one of the above-listed licenses.
+ */
+
+/**
+ * This fuzz target makes sure that whenever a compression dictionary can be
+ * loaded, the data can be round tripped.
+ */
+
+#include <stddef.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include "fuzz_helpers.h"
+#include "zstd_helpers.h"
+#include "fuzz_data_producer.h"
+
+/**
+ * Compresses the data and returns the compressed size or an error.
+ */
+static size_t compress(void* compressed, size_t compressedCapacity,
+                       void const* source, size_t sourceSize,
+                       void const* dict, size_t dictSize,
+                       ZSTD_dictLoadMethod_e dictLoadMethod,
+                       ZSTD_dictContentType_e dictContentType,
+                       int const refPrefix)
+{
+    ZSTD_CCtx* cctx = ZSTD_createCCtx();
+    if (refPrefix)
+        FUZZ_ZASSERT(ZSTD_CCtx_refPrefix_advanced(
+            cctx, dict, dictSize, dictContentType));
+    else 
+        FUZZ_ZASSERT(ZSTD_CCtx_loadDictionary_advanced(
+            cctx, dict, dictSize, dictLoadMethod, dictContentType));
+    size_t const compressedSize = ZSTD_compress2(
+            cctx, compressed, compressedCapacity, source, sourceSize);
+    ZSTD_freeCCtx(cctx);
+    return compressedSize;
+}
+
+static size_t decompress(void* result, size_t resultCapacity,
+                         void const* compressed, size_t compressedSize,
+                         void const* dict, size_t dictSize,
+                       ZSTD_dictLoadMethod_e dictLoadMethod,
+                         ZSTD_dictContentType_e dictContentType,
+                         int const refPrefix)
+{
+    ZSTD_DCtx* dctx = ZSTD_createDCtx();
+    if (refPrefix)
+        FUZZ_ZASSERT(ZSTD_DCtx_refPrefix_advanced(
+            dctx, dict, dictSize, dictContentType));
+    else
+        FUZZ_ZASSERT(ZSTD_DCtx_loadDictionary_advanced(
+            dctx, dict, dictSize, dictLoadMethod, dictContentType));
+    size_t const resultSize = ZSTD_decompressDCtx(
+            dctx, result, resultCapacity, compressed, compressedSize);
+    FUZZ_ZASSERT(resultSize);
+    ZSTD_freeDCtx(dctx);
+    return resultSize;
+}
+
+int LLVMFuzzerTestOneInput(const uint8_t *src, size_t size)
+{
+    FUZZ_dataProducer_t *producer = FUZZ_dataProducer_create(src, size);
+    int const refPrefix = FUZZ_dataProducer_uint32Range(producer, 0, 1) != 0;
+    ZSTD_dictLoadMethod_e const dlm =
+    size = FUZZ_dataProducer_uint32Range(producer, 0, 1);
+    ZSTD_dictContentType_e const dct =
+            FUZZ_dataProducer_uint32Range(producer, 0, 2);
+    size = FUZZ_dataProducer_remainingBytes(producer);
+
+    DEBUGLOG(2, "Dict load method %d", dlm);
+    DEBUGLOG(2, "Dict content type %d", dct);
+    DEBUGLOG(2, "Dict size %u", (unsigned)size);
+
+    void* const rBuf = FUZZ_malloc(size);
+    size_t const cBufSize = ZSTD_compressBound(size);
+    void* const cBuf = FUZZ_malloc(cBufSize);
+
+    size_t const cSize =
+            compress(cBuf, cBufSize, src, size, src, size, dlm, dct, refPrefix);
+    /* compression failing is okay */
+    if (ZSTD_isError(cSize)) {
+      FUZZ_ASSERT_MSG(dct != ZSTD_dct_rawContent, "Raw must always succeed!");
+      goto out;
+    }
+    size_t const rSize =
+            decompress(rBuf, size, cBuf, cSize, src, size, dlm, dct, refPrefix);
+    FUZZ_ASSERT_MSG(rSize == size, "Incorrect regenerated size");
+    FUZZ_ASSERT_MSG(!FUZZ_memcmp(src, rBuf, size), "Corruption!");
+
+out:
+    free(cBuf);
+    free(rBuf);
+    FUZZ_dataProducer_free(producer);
+    return 0;
+}
diff --git a/src/zstd/tests/fuzz/dictionary_round_trip.c b/src/zstd/tests/fuzz/dictionary_round_trip.c
new file mode 100644
index 000000000..7b7771e48
--- /dev/null
+++ b/src/zstd/tests/fuzz/dictionary_round_trip.c
@@ -0,0 +1,121 @@
+/*
+ * Copyright (c) 2016-2020, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under both the BSD-style license (found in the
+ * LICENSE file in the root directory of this source tree) and the GPLv2 (found
+ * in the COPYING file in the root directory of this source tree).
+ * You may select, at your option, one of the above-listed licenses.
+ */
+
+/**
+ * This fuzz target performs a zstd round-trip test (compress & decompress) with
+ * a dictionary, compares the result with the original, and calls abort() on
+ * corruption.
+ */
+
+#include <stddef.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include "fuzz_helpers.h"
+#include "zstd_helpers.h"
+#include "fuzz_data_producer.h"
+
+static ZSTD_CCtx *cctx = NULL;
+static ZSTD_DCtx *dctx = NULL;
+
+static size_t roundTripTest(void *result, size_t resultCapacity,
+                            void *compressed, size_t compressedCapacity,
+                            const void *src, size_t srcSize,
+                            FUZZ_dataProducer_t *producer)
+{
+    ZSTD_dictContentType_e dictContentType = ZSTD_dct_auto;
+    FUZZ_dict_t dict = FUZZ_train(src, srcSize, producer);
+    int const refPrefix = FUZZ_dataProducer_uint32Range(producer, 0, 1) != 0;
+    size_t cSize;
+    if (FUZZ_dataProducer_uint32Range(producer, 0, 15) == 0) {
+        int const cLevel = FUZZ_dataProducer_int32Range(producer, kMinClevel, kMaxClevel);
+
+        cSize = ZSTD_compress_usingDict(cctx,
+                compressed, compressedCapacity,
+                src, srcSize,
+                dict.buff, dict.size,
+                cLevel);
+    } else {
+        dictContentType = FUZZ_dataProducer_uint32Range(producer, 0, 2);
+        FUZZ_setRandomParameters(cctx, srcSize, producer);
+        /* Disable checksum so we can use sizes smaller than compress bound. */
+        FUZZ_ZASSERT(ZSTD_CCtx_setParameter(cctx, ZSTD_c_checksumFlag, 0));
+        if (refPrefix)
+            FUZZ_ZASSERT(ZSTD_CCtx_refPrefix_advanced(
+                cctx, dict.buff, dict.size,
+                dictContentType));
+        else 
+            FUZZ_ZASSERT(ZSTD_CCtx_loadDictionary_advanced(
+                cctx, dict.buff, dict.size,
+                (ZSTD_dictLoadMethod_e)FUZZ_dataProducer_uint32Range(producer, 0, 1),
+                dictContentType));
+        cSize = ZSTD_compress2(cctx, compressed, compressedCapacity, src, srcSize);
+    }
+    FUZZ_ZASSERT(cSize);
+    if (refPrefix)
+        FUZZ_ZASSERT(ZSTD_DCtx_refPrefix_advanced(
+            dctx, dict.buff, dict.size,
+            dictContentType));
+    else
+        FUZZ_ZASSERT(ZSTD_DCtx_loadDictionary_advanced(
+            dctx, dict.buff, dict.size,
+            (ZSTD_dictLoadMethod_e)FUZZ_dataProducer_uint32Range(producer, 0, 1),
+            dictContentType));
+    {
+        size_t const ret = ZSTD_decompressDCtx(
+                dctx, result, resultCapacity, compressed, cSize);
+        free(dict.buff);
+        return ret;
+    }
+}
+
+int LLVMFuzzerTestOneInput(const uint8_t *src, size_t 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 = FUZZ_dataProducer_reserveDataPrefix(producer);
+
+    size_t const rBufSize = size;
+    void* rBuf = FUZZ_malloc(rBufSize);
+    size_t cBufSize = ZSTD_compressBound(size);
+    void *cBuf;
+    /* Half of the time fuzz with a 1 byte smaller output size.
+     * This will still succeed because we force the checksum to be disabled,
+     * giving us 4 bytes of overhead.
+     */
+    cBufSize -= FUZZ_dataProducer_uint32Range(producer, 0, 1);
+    cBuf = FUZZ_malloc(cBufSize);
+
+    if (!cctx) {
+        cctx = ZSTD_createCCtx();
+        FUZZ_ASSERT(cctx);
+    }
+    if (!dctx) {
+        dctx = ZSTD_createDCtx();
+        FUZZ_ASSERT(dctx);
+    }
+
+    {
+        size_t const result =
+            roundTripTest(rBuf, rBufSize, cBuf, cBufSize, src, size, producer);
+        FUZZ_ZASSERT(result);
+        FUZZ_ASSERT_MSG(result == size, "Incorrect regenerated size");
+        FUZZ_ASSERT_MSG(!FUZZ_memcmp(src, rBuf, size), "Corruption!");
+    }
+    free(rBuf);
+    free(cBuf);
+    FUZZ_dataProducer_free(producer);
+#ifndef STATEFUL_FUZZING
+    ZSTD_freeCCtx(cctx); cctx = NULL;
+    ZSTD_freeDCtx(dctx); dctx = NULL;
+#endif
+    return 0;
+}
diff --git a/src/zstd/tests/fuzz/dictionary_stream_round_trip.c b/src/zstd/tests/fuzz/dictionary_stream_round_trip.c
new file mode 100644
index 000000000..67e8c69ef
--- /dev/null
+++ b/src/zstd/tests/fuzz/dictionary_stream_round_trip.c
@@ -0,0 +1,206 @@
+/*
+ * Copyright (c) 2016-2020, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under both the BSD-style license (found in the
+ * LICENSE file in the root directory of this source tree) and the GPLv2 (found
+ * in the COPYING file in the root directory of this source tree).
+ * You may select, at your option, one of the above-listed licenses.
+ */
+
+/**
+ * This fuzz target performs a zstd round-trip test (compress & decompress),
+ * compares the result with the original, and calls abort() on corruption.
+ */
+
+#define ZSTD_STATIC_LINKING_ONLY
+
+#include <stddef.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include "fuzz_helpers.h"
+#include "zstd_helpers.h"
+#include "fuzz_data_producer.h"
+
+ZSTD_CCtx *cctx = NULL;
+static ZSTD_DCtx *dctx = NULL;
+static uint8_t* cBuf = NULL;
+static uint8_t* rBuf = NULL;
+static size_t bufSize = 0;
+
+static ZSTD_outBuffer makeOutBuffer(uint8_t *dst, size_t capacity,
+                                    FUZZ_dataProducer_t *producer)
+{
+    ZSTD_outBuffer buffer = { dst, 0, 0 };
+
+    FUZZ_ASSERT(capacity > 0);
+    buffer.size = (FUZZ_dataProducer_uint32Range(producer, 1, capacity));
+    FUZZ_ASSERT(buffer.size <= capacity);
+
+    return buffer;
+}
+
+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_dataProducer_uint32Range(producer, 1, *size));
+    FUZZ_ASSERT(buffer.size <= *size);
+    *src += buffer.size;
+    *size -= buffer.size;
+
+    return buffer;
+}
+
+static size_t compress(uint8_t *dst, size_t capacity,
+                        const uint8_t *src, size_t srcSize,
+                        const uint8_t* dict, size_t dictSize,
+                        FUZZ_dataProducer_t *producer, int refPrefix,
+                        ZSTD_dictContentType_e dictContentType)
+{
+    size_t dstSize = 0;
+    ZSTD_CCtx_reset(cctx, ZSTD_reset_session_only);
+    FUZZ_setRandomParameters(cctx, srcSize, producer);
+
+    /* Disable checksum so we can use sizes smaller than compress bound. */
+    FUZZ_ZASSERT(ZSTD_CCtx_setParameter(cctx, ZSTD_c_checksumFlag, 0));
+    if (refPrefix)
+        FUZZ_ZASSERT(ZSTD_CCtx_refPrefix_advanced(
+            cctx, dict, dictSize,
+            dictContentType));
+    else
+        FUZZ_ZASSERT(ZSTD_CCtx_loadDictionary_advanced(
+            cctx, dict, dictSize,
+            (ZSTD_dictLoadMethod_e)FUZZ_dataProducer_uint32Range(producer, 0, 1),
+            dictContentType));
+
+    while (srcSize > 0) {
+        ZSTD_inBuffer in = makeInBuffer(&src, &srcSize, producer);
+        /* Mode controls the action. If mode == -1 we pick a new mode */
+        int mode = -1;
+        while (in.pos < in.size || mode != -1) {
+            ZSTD_outBuffer out = makeOutBuffer(dst, capacity, producer);
+            /* Previous action finished, pick a new mode. */
+            if (mode == -1) mode = FUZZ_dataProducer_uint32Range(producer, 0, 9);
+            switch (mode) {
+                case 0: /* fall-through */
+                case 1: /* fall-through */
+                case 2: {
+                    size_t const ret =
+                        ZSTD_compressStream2(cctx, &out, &in, ZSTD_e_flush);
+                    FUZZ_ZASSERT(ret);
+                    if (ret == 0)
+                        mode = -1;
+                    break;
+                }
+                case 3: {
+                    size_t ret =
+                        ZSTD_compressStream2(cctx, &out, &in, ZSTD_e_end);
+                    FUZZ_ZASSERT(ret);
+                    /* Reset the compressor when the frame is finished */
+                    if (ret == 0) {
+                        ZSTD_CCtx_reset(cctx, ZSTD_reset_session_only);
+                        if (FUZZ_dataProducer_uint32Range(producer, 0, 7) == 0) {
+                            size_t const remaining = in.size - in.pos;
+                            FUZZ_setRandomParameters(cctx, remaining, producer);
+                        }
+                        mode = -1;
+                    }
+                    break;
+                }
+                case 4: {
+                    ZSTD_inBuffer nullIn = { NULL, 0, 0 };
+                    ZSTD_outBuffer nullOut = { NULL, 0, 0 };
+                    size_t const ret = ZSTD_compressStream2(cctx, &nullOut, &nullIn, ZSTD_e_continue);
+                    FUZZ_ZASSERT(ret);
+                }
+                /* fall-through */
+                default: {
+                    size_t const ret =
+                        ZSTD_compressStream2(cctx, &out, &in, ZSTD_e_continue);
+                    FUZZ_ZASSERT(ret);
+                    mode = -1;
+                }
+            }
+            dst += out.pos;
+            dstSize += out.pos;
+            capacity -= out.pos;
+        }
+    }
+    for (;;) {
+        ZSTD_inBuffer in = {NULL, 0, 0};
+        ZSTD_outBuffer out = makeOutBuffer(dst, capacity, producer);
+        size_t const ret = ZSTD_compressStream2(cctx, &out, &in, ZSTD_e_end);
+        FUZZ_ZASSERT(ret);
+
+        dst += out.pos;
+        dstSize += out.pos;
+        capacity -= out.pos;
+        if (ret == 0)
+            break;
+    }
+    return dstSize;
+}
+
+int LLVMFuzzerTestOneInput(const uint8_t *src, size_t size)
+{
+    size_t neededBufSize;
+
+    /* 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 = FUZZ_dataProducer_reserveDataPrefix(producer);
+
+    neededBufSize = ZSTD_compressBound(size) * 15;
+
+    /* Allocate all buffers and contexts if not already allocated */
+    if (neededBufSize > bufSize) {
+        free(cBuf);
+        free(rBuf);
+        cBuf = (uint8_t*)FUZZ_malloc(neededBufSize);
+        rBuf = (uint8_t*)FUZZ_malloc(neededBufSize);
+        bufSize = neededBufSize;
+    }
+    if (!cctx) {
+        cctx = ZSTD_createCCtx();
+        FUZZ_ASSERT(cctx);
+    }
+    if (!dctx) {
+        dctx = ZSTD_createDCtx();
+        FUZZ_ASSERT(dctx);
+    }
+
+    {
+        ZSTD_dictContentType_e dictContentType = FUZZ_dataProducer_uint32Range(producer, 0, 2);
+        FUZZ_dict_t dict = FUZZ_train(src, size, producer);
+        int const refPrefix = FUZZ_dataProducer_uint32Range(producer, 0, 1) != 0;
+
+        size_t const cSize = compress(cBuf, neededBufSize, src, size, dict.buff, dict.size, producer, refPrefix, dictContentType);
+
+        if (refPrefix)
+            FUZZ_ZASSERT(ZSTD_DCtx_refPrefix_advanced(
+                dctx, dict.buff, dict.size,
+                dictContentType));
+        else
+            FUZZ_ZASSERT(ZSTD_DCtx_loadDictionary_advanced(
+                dctx, dict.buff, dict.size,
+                (ZSTD_dictLoadMethod_e)FUZZ_dataProducer_uint32Range(producer, 0, 1),
+                dictContentType));
+        size_t const rSize =
+            ZSTD_decompressDCtx(dctx, rBuf, neededBufSize, cBuf, cSize);
+        FUZZ_ZASSERT(rSize);
+        FUZZ_ASSERT_MSG(rSize == size, "Incorrect regenerated size");
+        FUZZ_ASSERT_MSG(!FUZZ_memcmp(src, rBuf, size), "Corruption!");
+        free(dict.buff);
+    }
+
+    FUZZ_dataProducer_free(producer);
+#ifndef STATEFUL_FUZZING
+    ZSTD_freeCCtx(cctx); cctx = NULL;
+    ZSTD_freeDCtx(dctx); dctx = NULL;
+#endif
+    return 0;
+}
diff --git a/src/zstd/tests/fuzz/fuzz.h b/src/zstd/tests/fuzz/fuzz.h
new file mode 100644
index 000000000..8ee964536
--- /dev/null
+++ b/src/zstd/tests/fuzz/fuzz.h
@@ -0,0 +1,53 @@
+/*
+ * Copyright (c) 2016-2020, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under both the BSD-style license (found in the
+ * LICENSE file in the root directory of this source tree) and the GPLv2 (found
+ * in the COPYING file in the root directory of this source tree).
+ * You may select, at your option, one of the above-listed licenses.
+ */
+
+/**
+ * Fuzz target interface.
+ * Fuzz targets have some common parameters passed as macros during compilation.
+ * Check the documentation for each individual fuzzer for more parameters.
+ *
+ * @param STATEFUL_FUZZING:
+ *        Define this to reuse state between fuzzer runs. This can be useful to
+ *        test code paths which are only executed when contexts are reused.
+ *        WARNING: Makes reproducing crashes much harder.
+ *        Default: Not defined.
+ * @param DEBUGLEVEL:
+ *        This is a parameter for the zstd library. Defining `DEBUGLEVEL=1`
+ *        enables assert() statements in the zstd library. Higher levels enable
+ *        logging, so aren't recommended. Defining `DEBUGLEVEL=1` is
+ *        recommended.
+ * @param MEM_FORCE_MEMORY_ACCESS:
+ *        This flag controls how the zstd library accesses unaligned memory.
+ *        It can be undefined, or 0 through 2. If it is undefined, it selects
+ *        the method to use based on the compiler. If testing with UBSAN set
+ *        MEM_FORCE_MEMORY_ACCESS=0 to use the standard compliant method.
+ * @param FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
+ *        This is the canonical flag to enable deterministic builds for fuzzing.
+ *        Changes to zstd for fuzzing are gated behind this define.
+ *        It is recommended to define this when building zstd for fuzzing.
+ */
+
+#ifndef FUZZ_H
+#define FUZZ_H
+
+#include <stddef.h>
+#include <stdint.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+int LLVMFuzzerTestOneInput(const uint8_t *src, size_t size);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
diff --git a/src/zstd/tests/fuzz/fuzz.py b/src/zstd/tests/fuzz/fuzz.py
new file mode 100755
index 000000000..6875d1d60
--- /dev/null
+++ b/src/zstd/tests/fuzz/fuzz.py
@@ -0,0 +1,887 @@
+#!/usr/bin/env python
+
+# ################################################################
+# Copyright (c) 2016-2020, Facebook, Inc.
+# All rights reserved.
+#
+# This source code is licensed under both the BSD-style license (found in the
+# LICENSE file in the root directory of this source tree) and the GPLv2 (found
+# in the COPYING file in the root directory of this source tree).
+# You may select, at your option, one of the above-listed licenses.
+# ##########################################################################
+
+import argparse
+import contextlib
+import os
+import re
+import shlex
+import shutil
+import subprocess
+import sys
+import tempfile
+
+
+def abs_join(a, *p):
+    return os.path.abspath(os.path.join(a, *p))
+
+
+class InputType(object):
+    RAW_DATA = 1
+    COMPRESSED_DATA = 2
+    DICTIONARY_DATA = 3
+
+
+class FrameType(object):
+    ZSTD = 1
+    BLOCK = 2
+
+
+class TargetInfo(object):
+    def __init__(self, input_type, frame_type=FrameType.ZSTD):
+        self.input_type = input_type
+        self.frame_type = frame_type
+
+
+# Constants
+FUZZ_DIR = os.path.abspath(os.path.dirname(__file__))
+CORPORA_DIR = abs_join(FUZZ_DIR, 'corpora')
+TARGET_INFO = {
+    'simple_round_trip': TargetInfo(InputType.RAW_DATA),
+    'stream_round_trip': TargetInfo(InputType.RAW_DATA),
+    'block_round_trip': TargetInfo(InputType.RAW_DATA, FrameType.BLOCK),
+    'simple_decompress': TargetInfo(InputType.COMPRESSED_DATA),
+    'stream_decompress': TargetInfo(InputType.COMPRESSED_DATA),
+    'block_decompress': TargetInfo(InputType.COMPRESSED_DATA, FrameType.BLOCK),
+    'dictionary_round_trip': TargetInfo(InputType.RAW_DATA),
+    'dictionary_decompress': TargetInfo(InputType.COMPRESSED_DATA),
+    'zstd_frame_info': TargetInfo(InputType.COMPRESSED_DATA),
+    'simple_compress': TargetInfo(InputType.RAW_DATA),
+    'dictionary_loader': TargetInfo(InputType.DICTIONARY_DATA),
+    'raw_dictionary_round_trip': TargetInfo(InputType.RAW_DATA),
+    'dictionary_stream_round_trip': TargetInfo(InputType.RAW_DATA),
+}
+TARGETS = list(TARGET_INFO.keys())
+ALL_TARGETS = TARGETS + ['all']
+FUZZ_RNG_SEED_SIZE = 4
+
+# Standard environment variables
+CC = os.environ.get('CC', 'cc')
+CXX = os.environ.get('CXX', 'c++')
+CPPFLAGS = os.environ.get('CPPFLAGS', '')
+CFLAGS = os.environ.get('CFLAGS', '-O3')
+CXXFLAGS = os.environ.get('CXXFLAGS', CFLAGS)
+LDFLAGS = os.environ.get('LDFLAGS', '')
+MFLAGS = os.environ.get('MFLAGS', '-j')
+
+# Fuzzing environment variables
+LIB_FUZZING_ENGINE = os.environ.get('LIB_FUZZING_ENGINE', 'libregression.a')
+AFL_FUZZ = os.environ.get('AFL_FUZZ', 'afl-fuzz')
+DECODECORPUS = os.environ.get('DECODECORPUS',
+                              abs_join(FUZZ_DIR, '..', 'decodecorpus'))
+ZSTD = os.environ.get('ZSTD', abs_join(FUZZ_DIR, '..', '..', 'zstd'))
+
+# Sanitizer environment variables
+MSAN_EXTRA_CPPFLAGS = os.environ.get('MSAN_EXTRA_CPPFLAGS', '')
+MSAN_EXTRA_CFLAGS = os.environ.get('MSAN_EXTRA_CFLAGS', '')
+MSAN_EXTRA_CXXFLAGS = os.environ.get('MSAN_EXTRA_CXXFLAGS', '')
+MSAN_EXTRA_LDFLAGS = os.environ.get('MSAN_EXTRA_LDFLAGS', '')
+
+
+def create(r):
+    d = os.path.abspath(r)
+    if not os.path.isdir(d):
+        os.makedirs(d)
+    return d
+
+
+def check(r):
+    d = os.path.abspath(r)
+    if not os.path.isdir(d):
+        return None
+    return d
+
+
+@contextlib.contextmanager
+def tmpdir():
+    dirpath = tempfile.mkdtemp()
+    try:
+        yield dirpath
+    finally:
+        shutil.rmtree(dirpath, ignore_errors=True)
+
+
+def parse_targets(in_targets):
+    targets = set()
+    for target in in_targets:
+        if not target:
+            continue
+        if target == 'all':
+            targets = targets.union(TARGETS)
+        elif target in TARGETS:
+            targets.add(target)
+        else:
+            raise RuntimeError('{} is not a valid target'.format(target))
+    return list(targets)
+
+
+def targets_parser(args, description):
+    parser = argparse.ArgumentParser(prog=args.pop(0), description=description)
+    parser.add_argument(
+        'TARGET',
+        nargs='*',
+        type=str,
+        help='Fuzz target(s) to build {{{}}}'.format(', '.join(ALL_TARGETS)))
+    args, extra = parser.parse_known_args(args)
+    args.extra = extra
+
+    args.TARGET = parse_targets(args.TARGET)
+
+    return args
+
+
+def parse_env_flags(args, flags):
+    """
+    Look for flags set by environment variables.
+    """
+    san_flags = ','.join(re.findall('-fsanitize=((?:[a-z]+,?)+)', flags))
+    nosan_flags = ','.join(re.findall('-fno-sanitize=((?:[a-z]+,?)+)', flags))
+
+    def set_sanitizer(sanitizer, default, san, nosan):
+        if sanitizer in san and sanitizer in nosan:
+            raise RuntimeError('-fno-sanitize={s} and -fsanitize={s} passed'.
+                               format(s=sanitizer))
+        if sanitizer in san:
+            return True
+        if sanitizer in nosan:
+            return False
+        return default
+
+    san = set(san_flags.split(','))
+    nosan = set(nosan_flags.split(','))
+
+    args.asan = set_sanitizer('address', args.asan, san, nosan)
+    args.msan = set_sanitizer('memory', args.msan, san, nosan)
+    args.ubsan = set_sanitizer('undefined', args.ubsan, san, nosan)
+
+    args.sanitize = args.asan or args.msan or args.ubsan
+
+    return args
+
+
+def compiler_version(cc, cxx):
+    """
+    Determines the compiler and version.
+    Only works for clang and gcc.
+    """
+    cc_version_bytes = subprocess.check_output([cc, "--version"])
+    cxx_version_bytes = subprocess.check_output([cxx, "--version"])
+    compiler = None
+    version = None
+    if b'clang' in cc_version_bytes:
+        assert(b'clang' in cxx_version_bytes)
+        compiler = 'clang'
+    elif b'gcc' in cc_version_bytes:
+        assert(b'gcc' in cxx_version_bytes or b'g++' in cxx_version_bytes)
+        compiler = 'gcc'
+    if compiler is not None:
+        version_regex = b'([0-9])+\.([0-9])+\.([0-9])+'
+        version_match = re.search(version_regex, cc_version_bytes)
+        version = tuple(int(version_match.group(i)) for i in range(1, 4))
+    return compiler, version
+
+
+def overflow_ubsan_flags(cc, cxx):
+    compiler, version = compiler_version(cc, cxx)
+    if compiler == 'gcc':
+        return ['-fno-sanitize=signed-integer-overflow']
+    if compiler == 'clang' and version >= (5, 0, 0):
+        return ['-fno-sanitize=pointer-overflow']
+    return []
+
+
+def build_parser(args):
+    description = """
+    Cleans the repository and builds a fuzz target (or all).
+    Many flags default to environment variables (default says $X='y').
+    Options that aren't enabling features default to the correct values for
+    zstd.
+    Enable sanitizers with --enable-*san.
+    For regression testing just build.
+    For libFuzzer set LIB_FUZZING_ENGINE and pass --enable-coverage.
+    For AFL set CC and CXX to AFL's compilers and set
+    LIB_FUZZING_ENGINE='libregression.a'.
+    """
+    parser = argparse.ArgumentParser(prog=args.pop(0), description=description)
+    parser.add_argument(
+        '--lib-fuzzing-engine',
+        dest='lib_fuzzing_engine',
+        type=str,
+        default=LIB_FUZZING_ENGINE,
+        help=('The fuzzing engine to use e.g. /path/to/libFuzzer.a '
+              "(default: $LIB_FUZZING_ENGINE='{})".format(LIB_FUZZING_ENGINE)))
+
+    fuzz_group = parser.add_mutually_exclusive_group()
+    fuzz_group.add_argument(
+        '--enable-coverage',
+        dest='coverage',
+        action='store_true',
+        help='Enable coverage instrumentation (-fsanitize-coverage)')
+    fuzz_group.add_argument(
+        '--enable-fuzzer',
+        dest='fuzzer',
+        action='store_true',
+        help=('Enable clang fuzzer (-fsanitize=fuzzer). When enabled '
+              'LIB_FUZZING_ENGINE is ignored')
+    )
+
+    parser.add_argument(
+        '--enable-asan', dest='asan', action='store_true', help='Enable UBSAN')
+    parser.add_argument(
+        '--enable-ubsan',
+        dest='ubsan',
+        action='store_true',
+        help='Enable UBSAN')
+    parser.add_argument(
+        '--enable-ubsan-pointer-overflow',
+        dest='ubsan_pointer_overflow',
+        action='store_true',
+        help='Enable UBSAN pointer overflow check (known failure)')
+    parser.add_argument(
+        '--enable-msan', dest='msan', action='store_true', help='Enable MSAN')
+    parser.add_argument(
+        '--enable-msan-track-origins', dest='msan_track_origins',
+        action='store_true', help='Enable MSAN origin tracking')
+    parser.add_argument(
+        '--msan-extra-cppflags',
+        dest='msan_extra_cppflags',
+        type=str,
+        default=MSAN_EXTRA_CPPFLAGS,
+        help="Extra CPPFLAGS for MSAN (default: $MSAN_EXTRA_CPPFLAGS='{}')".
+        format(MSAN_EXTRA_CPPFLAGS))
+    parser.add_argument(
+        '--msan-extra-cflags',
+        dest='msan_extra_cflags',
+        type=str,
+        default=MSAN_EXTRA_CFLAGS,
+        help="Extra CFLAGS for MSAN (default: $MSAN_EXTRA_CFLAGS='{}')".format(
+            MSAN_EXTRA_CFLAGS))
+    parser.add_argument(
+        '--msan-extra-cxxflags',
+        dest='msan_extra_cxxflags',
+        type=str,
+        default=MSAN_EXTRA_CXXFLAGS,
+        help="Extra CXXFLAGS for MSAN (default: $MSAN_EXTRA_CXXFLAGS='{}')".
+        format(MSAN_EXTRA_CXXFLAGS))
+    parser.add_argument(
+        '--msan-extra-ldflags',
+        dest='msan_extra_ldflags',
+        type=str,
+        default=MSAN_EXTRA_LDFLAGS,
+        help="Extra LDFLAGS for MSAN (default: $MSAN_EXTRA_LDFLAGS='{}')".
+        format(MSAN_EXTRA_LDFLAGS))
+    parser.add_argument(
+        '--enable-sanitize-recover',
+        dest='sanitize_recover',
+        action='store_true',
+        help='Non-fatal sanitizer errors where possible')
+    parser.add_argument(
+        '--debug',
+        dest='debug',
+        type=int,
+        default=1,
+        help='Set DEBUGLEVEL (default: 1)')
+    parser.add_argument(
+        '--force-memory-access',
+        dest='memory_access',
+        type=int,
+        default=0,
+        help='Set MEM_FORCE_MEMORY_ACCESS (default: 0)')
+    parser.add_argument(
+        '--fuzz-rng-seed-size',
+        dest='fuzz_rng_seed_size',
+        type=int,
+        default=4,
+        help='Set FUZZ_RNG_SEED_SIZE (default: 4)')
+    parser.add_argument(
+        '--disable-fuzzing-mode',
+        dest='fuzzing_mode',
+        action='store_false',
+        help='Do not define FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION')
+    parser.add_argument(
+        '--enable-stateful-fuzzing',
+        dest='stateful_fuzzing',
+        action='store_true',
+        help='Reuse contexts between runs (makes reproduction impossible)')
+    parser.add_argument(
+        '--cc',
+        dest='cc',
+        type=str,
+        default=CC,
+        help="CC (default: $CC='{}')".format(CC))
+    parser.add_argument(
+        '--cxx',
+        dest='cxx',
+        type=str,
+        default=CXX,
+        help="CXX (default: $CXX='{}')".format(CXX))
+    parser.add_argument(
+        '--cppflags',
+        dest='cppflags',
+        type=str,
+        default=CPPFLAGS,
+        help="CPPFLAGS (default: $CPPFLAGS='{}')".format(CPPFLAGS))
+    parser.add_argument(
+        '--cflags',
+        dest='cflags',
+        type=str,
+        default=CFLAGS,
+        help="CFLAGS (default: $CFLAGS='{}')".format(CFLAGS))
+    parser.add_argument(
+        '--cxxflags',
+        dest='cxxflags',
+        type=str,
+        default=CXXFLAGS,
+        help="CXXFLAGS (default: $CXXFLAGS='{}')".format(CXXFLAGS))
+    parser.add_argument(
+        '--ldflags',
+        dest='ldflags',
+        type=str,
+        default=LDFLAGS,
+        help="LDFLAGS (default: $LDFLAGS='{}')".format(LDFLAGS))
+    parser.add_argument(
+        '--mflags',
+        dest='mflags',
+        type=str,
+        default=MFLAGS,
+        help="Extra Make flags (default: $MFLAGS='{}')".format(MFLAGS))
+    parser.add_argument(
+        'TARGET',
+        nargs='*',
+        type=str,
+        help='Fuzz target(s) to build {{{}}}'.format(', '.join(ALL_TARGETS))
+    )
+    args = parser.parse_args(args)
+    args = parse_env_flags(args, ' '.join(
+        [args.cppflags, args.cflags, args.cxxflags, args.ldflags]))
+
+    # Check option sanity
+    if args.msan and (args.asan or args.ubsan):
+        raise RuntimeError('MSAN may not be used with any other sanitizers')
+    if args.msan_track_origins and not args.msan:
+        raise RuntimeError('--enable-msan-track-origins requires MSAN')
+    if args.ubsan_pointer_overflow and not args.ubsan:
+        raise RuntimeError('--enable-ubsan-pointer-overflow requires UBSAN')
+    if args.sanitize_recover and not args.sanitize:
+        raise RuntimeError('--enable-sanitize-recover but no sanitizers used')
+
+    return args
+
+
+def build(args):
+    try:
+        args = build_parser(args)
+    except Exception as e:
+        print(e)
+        return 1
+    # The compilation flags we are setting
+    targets = args.TARGET
+    cc = args.cc
+    cxx = args.cxx
+    cppflags = shlex.split(args.cppflags)
+    cflags = shlex.split(args.cflags)
+    ldflags = shlex.split(args.ldflags)
+    cxxflags = shlex.split(args.cxxflags)
+    mflags = shlex.split(args.mflags)
+    # Flags to be added to both cflags and cxxflags
+    common_flags = []
+
+    cppflags += [
+        '-DDEBUGLEVEL={}'.format(args.debug),
+        '-DMEM_FORCE_MEMORY_ACCESS={}'.format(args.memory_access),
+        '-DFUZZ_RNG_SEED_SIZE={}'.format(args.fuzz_rng_seed_size),
+    ]
+
+    # Set flags for options
+    assert not (args.fuzzer and args.coverage)
+    if args.coverage:
+        common_flags += [
+            '-fsanitize-coverage=trace-pc-guard,indirect-calls,trace-cmp'
+        ]
+    if args.fuzzer:
+        common_flags += ['-fsanitize=fuzzer']
+        args.lib_fuzzing_engine = ''
+
+    mflags += ['LIB_FUZZING_ENGINE={}'.format(args.lib_fuzzing_engine)]
+
+    if args.sanitize_recover:
+        recover_flags = ['-fsanitize-recover=all']
+    else:
+        recover_flags = ['-fno-sanitize-recover=all']
+    if args.sanitize:
+        common_flags += recover_flags
+
+    if args.msan:
+        msan_flags = ['-fsanitize=memory']
+        if args.msan_track_origins:
+            msan_flags += ['-fsanitize-memory-track-origins']
+        common_flags += msan_flags
+        # Append extra MSAN flags (it might require special setup)
+        cppflags += [args.msan_extra_cppflags]
+        cflags += [args.msan_extra_cflags]
+        cxxflags += [args.msan_extra_cxxflags]
+        ldflags += [args.msan_extra_ldflags]
+
+    if args.asan:
+        common_flags += ['-fsanitize=address']
+
+    if args.ubsan:
+        ubsan_flags = ['-fsanitize=undefined']
+        if not args.ubsan_pointer_overflow:
+            ubsan_flags += overflow_ubsan_flags(cc, cxx)
+        common_flags += ubsan_flags
+
+    if args.stateful_fuzzing:
+        cppflags += ['-DSTATEFUL_FUZZING']
+
+    if args.fuzzing_mode:
+        cppflags += ['-DFUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION']
+
+    if args.lib_fuzzing_engine == 'libregression.a':
+        targets = ['libregression.a'] + targets
+
+    # Append the common flags
+    cflags += common_flags
+    cxxflags += common_flags
+
+    # Prepare the flags for Make
+    cc_str = "CC={}".format(cc)
+    cxx_str = "CXX={}".format(cxx)
+    cppflags_str = "CPPFLAGS={}".format(' '.join(cppflags))
+    cflags_str = "CFLAGS={}".format(' '.join(cflags))
+    cxxflags_str = "CXXFLAGS={}".format(' '.join(cxxflags))
+    ldflags_str = "LDFLAGS={}".format(' '.join(ldflags))
+
+    # Print the flags
+    print('MFLAGS={}'.format(' '.join(mflags)))
+    print(cc_str)
+    print(cxx_str)
+    print(cppflags_str)
+    print(cflags_str)
+    print(cxxflags_str)
+    print(ldflags_str)
+
+    # Clean and build
+    clean_cmd = ['make', 'clean'] + mflags
+    print(' '.join(clean_cmd))
+    subprocess.check_call(clean_cmd)
+    build_cmd = [
+        'make',
+        cc_str,
+        cxx_str,
+        cppflags_str,
+        cflags_str,
+        cxxflags_str,
+        ldflags_str,
+    ] + mflags + targets
+    print(' '.join(build_cmd))
+    subprocess.check_call(build_cmd)
+    return 0
+
+
+def libfuzzer_parser(args):
+    description = """
+    Runs a libfuzzer binary.
+    Passes all extra arguments to libfuzzer.
+    The fuzzer should have been build with LIB_FUZZING_ENGINE pointing to
+    libFuzzer.a.
+    Generates output in the CORPORA directory, puts crashes in the ARTIFACT
+    directory, and takes extra input from the SEED directory.
+    To merge AFL's output pass the SEED as AFL's output directory and pass
+    '-merge=1'.
+    """
+    parser = argparse.ArgumentParser(prog=args.pop(0), description=description)
+    parser.add_argument(
+        '--corpora',
+        type=str,
+        help='Override the default corpora dir (default: {})'.format(
+            abs_join(CORPORA_DIR, 'TARGET')))
+    parser.add_argument(
+        '--artifact',
+        type=str,
+        help='Override the default artifact dir (default: {})'.format(
+            abs_join(CORPORA_DIR, 'TARGET-crash')))
+    parser.add_argument(
+        '--seed',
+        type=str,
+        help='Override the default seed dir (default: {})'.format(
+            abs_join(CORPORA_DIR, 'TARGET-seed')))
+    parser.add_argument(
+        'TARGET',
+        type=str,
+        help='Fuzz target(s) to build {{{}}}'.format(', '.join(TARGETS)))
+    args, extra = parser.parse_known_args(args)
+    args.extra = extra
+
+    if args.TARGET and args.TARGET not in TARGETS:
+        raise RuntimeError('{} is not a valid target'.format(args.TARGET))
+
+    return args
+
+
+def libfuzzer(target, corpora=None, artifact=None, seed=None, extra_args=None):
+    if corpora is None:
+        corpora = abs_join(CORPORA_DIR, target)
+    if artifact is None:
+        artifact = abs_join(CORPORA_DIR, '{}-crash'.format(target))
+    if seed is None:
+        seed = abs_join(CORPORA_DIR, '{}-seed'.format(target))
+    if extra_args is None:
+        extra_args = []
+
+    target = abs_join(FUZZ_DIR, target)
+
+    corpora = [create(corpora)]
+    artifact = create(artifact)
+    seed = check(seed)
+
+    corpora += [artifact]
+    if seed is not None:
+        corpora += [seed]
+
+    cmd = [target, '-artifact_prefix={}/'.format(artifact)]
+    cmd += corpora + extra_args
+    print(' '.join(cmd))
+    subprocess.check_call(cmd)
+
+
+def libfuzzer_cmd(args):
+    try:
+        args = libfuzzer_parser(args)
+    except Exception as e:
+        print(e)
+        return 1
+    libfuzzer(args.TARGET, args.corpora, args.artifact, args.seed, args.extra)
+    return 0
+
+
+def afl_parser(args):
+    description = """
+    Runs an afl-fuzz job.
+    Passes all extra arguments to afl-fuzz.
+    The fuzzer should have been built with CC/CXX set to the AFL compilers,
+    and with LIB_FUZZING_ENGINE='libregression.a'.
+    Takes input from CORPORA and writes output to OUTPUT.
+    Uses AFL_FUZZ as the binary (set from flag or environment variable).
+    """
+    parser = argparse.ArgumentParser(prog=args.pop(0), description=description)
+    parser.add_argument(
+        '--corpora',
+        type=str,
+        help='Override the default corpora dir (default: {})'.format(
+            abs_join(CORPORA_DIR, 'TARGET')))
+    parser.add_argument(
+        '--output',
+        type=str,
+        help='Override the default AFL output dir (default: {})'.format(
+            abs_join(CORPORA_DIR, 'TARGET-afl')))
+    parser.add_argument(
+        '--afl-fuzz',
+        type=str,
+        default=AFL_FUZZ,
+        help='AFL_FUZZ (default: $AFL_FUZZ={})'.format(AFL_FUZZ))
+    parser.add_argument(
+        'TARGET',
+        type=str,
+        help='Fuzz target(s) to build {{{}}}'.format(', '.join(TARGETS)))
+    args, extra = parser.parse_known_args(args)
+    args.extra = extra
+
+    if args.TARGET and args.TARGET not in TARGETS:
+        raise RuntimeError('{} is not a valid target'.format(args.TARGET))
+
+    if not args.corpora:
+        args.corpora = abs_join(CORPORA_DIR, args.TARGET)
+    if not args.output:
+        args.output = abs_join(CORPORA_DIR, '{}-afl'.format(args.TARGET))
+
+    return args
+
+
+def afl(args):
+    try:
+        args = afl_parser(args)
+    except Exception as e:
+        print(e)
+        return 1
+    target = abs_join(FUZZ_DIR, args.TARGET)
+
+    corpora = create(args.corpora)
+    output = create(args.output)
+
+    cmd = [args.afl_fuzz, '-i', corpora, '-o', output] + args.extra
+    cmd += [target, '@@']
+    print(' '.join(cmd))
+    subprocess.call(cmd)
+    return 0
+
+
+def regression(args):
+    try:
+        description = """
+        Runs one or more regression tests.
+        The fuzzer should have been built with with
+        LIB_FUZZING_ENGINE='libregression.a'.
+        Takes input from CORPORA.
+        """
+        args = targets_parser(args, description)
+    except Exception as e:
+        print(e)
+        return 1
+    for target in args.TARGET:
+        corpora = create(abs_join(CORPORA_DIR, target))
+        target = abs_join(FUZZ_DIR, target)
+        cmd = [target, corpora]
+        print(' '.join(cmd))
+        subprocess.check_call(cmd)
+    return 0
+
+
+def gen_parser(args):
+    description = """
+    Generate a seed corpus appropriate for TARGET with data generated with
+    decodecorpus.
+    The fuzz inputs are prepended with a seed before the zstd data, so the
+    output of decodecorpus shouldn't be used directly.
+    Generates NUMBER samples prepended with FUZZ_RNG_SEED_SIZE random bytes and
+    puts the output in SEED.
+    DECODECORPUS is the decodecorpus binary, and must already be built.
+    """
+    parser = argparse.ArgumentParser(prog=args.pop(0), description=description)
+    parser.add_argument(
+        '--number',
+        '-n',
+        type=int,
+        default=100,
+        help='Number of samples to generate')
+    parser.add_argument(
+        '--max-size-log',
+        type=int,
+        default=18,
+        help='Maximum sample size to generate')
+    parser.add_argument(
+        '--seed',
+        type=str,
+        help='Override the default seed dir (default: {})'.format(
+            abs_join(CORPORA_DIR, 'TARGET-seed')))
+    parser.add_argument(
+        '--decodecorpus',
+        type=str,
+        default=DECODECORPUS,
+        help="decodecorpus binary (default: $DECODECORPUS='{}')".format(
+            DECODECORPUS))
+    parser.add_argument(
+        '--zstd',
+        type=str,
+        default=ZSTD,
+        help="zstd binary (default: $ZSTD='{}')".format(ZSTD))
+    parser.add_argument(
+        '--fuzz-rng-seed-size',
+        type=int,
+        default=4,
+        help="FUZZ_RNG_SEED_SIZE used for generate the samples (must match)"
+    )
+    parser.add_argument(
+        'TARGET',
+        type=str,
+        help='Fuzz target(s) to build {{{}}}'.format(', '.join(TARGETS)))
+    args, extra = parser.parse_known_args(args)
+    args.extra = extra
+
+    if args.TARGET and args.TARGET not in TARGETS:
+        raise RuntimeError('{} is not a valid target'.format(args.TARGET))
+
+    if not args.seed:
+        args.seed = abs_join(CORPORA_DIR, '{}-seed'.format(args.TARGET))
+
+    if not os.path.isfile(args.decodecorpus):
+        raise RuntimeError("{} is not a file run 'make -C {} decodecorpus'".
+                           format(args.decodecorpus, abs_join(FUZZ_DIR, '..')))
+
+    return args
+
+
+def gen(args):
+    try:
+        args = gen_parser(args)
+    except Exception as e:
+        print(e)
+        return 1
+
+    seed = create(args.seed)
+    with tmpdir() as compressed, tmpdir() as decompressed, tmpdir() as dict:
+        info = TARGET_INFO[args.TARGET]
+
+        if info.input_type == InputType.DICTIONARY_DATA:
+            number = max(args.number, 1000)
+        else:
+            number = args.number
+        cmd = [
+            args.decodecorpus,
+            '-n{}'.format(args.number),
+            '-p{}/'.format(compressed),
+            '-o{}'.format(decompressed),
+        ]
+
+        if info.frame_type == FrameType.BLOCK:
+            cmd += [
+                '--gen-blocks',
+                '--max-block-size-log={}'.format(min(args.max_size_log, 17))
+            ]
+        else:
+            cmd += ['--max-content-size-log={}'.format(args.max_size_log)]
+
+        print(' '.join(cmd))
+        subprocess.check_call(cmd)
+
+        if info.input_type == InputType.RAW_DATA:
+            print('using decompressed data in {}'.format(decompressed))
+            samples = decompressed
+        elif info.input_type == InputType.COMPRESSED_DATA:
+            print('using compressed data in {}'.format(compressed))
+            samples = compressed
+        else:
+            assert info.input_type == InputType.DICTIONARY_DATA
+            print('making dictionary data from {}'.format(decompressed))
+            samples = dict
+            min_dict_size_log = 9
+            max_dict_size_log = max(min_dict_size_log + 1, args.max_size_log)
+            for dict_size_log in range(min_dict_size_log, max_dict_size_log):
+                dict_size = 1 << dict_size_log
+                cmd = [
+                    args.zstd,
+                    '--train',
+                    '-r', decompressed,
+                    '--maxdict={}'.format(dict_size),
+                    '-o', abs_join(dict, '{}.zstd-dict'.format(dict_size))
+                ]
+                print(' '.join(cmd))
+                subprocess.check_call(cmd)
+
+        # Copy the samples over and prepend the RNG seeds
+        for name in os.listdir(samples):
+            samplename = abs_join(samples, name)
+            outname = abs_join(seed, name)
+            with open(samplename, 'rb') as sample:
+                with open(outname, 'wb') as out:
+                    CHUNK_SIZE = 131072
+                    chunk = sample.read(CHUNK_SIZE)
+                    while len(chunk) > 0:
+                        out.write(chunk)
+                        chunk = sample.read(CHUNK_SIZE)
+    return 0
+
+
+def minimize(args):
+    try:
+        description = """
+        Runs a libfuzzer fuzzer with -merge=1 to build a minimal corpus in
+        TARGET_seed_corpus. All extra args are passed to libfuzzer.
+        """
+        args = targets_parser(args, description)
+    except Exception as e:
+        print(e)
+        return 1
+
+    for target in args.TARGET:
+        # Merge the corpus + anything else into the seed_corpus
+        corpus = abs_join(CORPORA_DIR, target)
+        seed_corpus = abs_join(CORPORA_DIR, "{}_seed_corpus".format(target))
+        extra_args = [corpus, "-merge=1"] + args.extra
+        libfuzzer(target, corpora=seed_corpus, extra_args=extra_args)
+        seeds = set(os.listdir(seed_corpus))
+        # Copy all crashes directly into the seed_corpus if not already present
+        crashes = abs_join(CORPORA_DIR, '{}-crash'.format(target))
+        for crash in os.listdir(crashes):
+            if crash not in seeds:
+                shutil.copy(abs_join(crashes, crash), seed_corpus)
+                seeds.add(crash)
+
+
+def zip_cmd(args):
+    try:
+        description = """
+        Zips up the seed corpus.
+        """
+        args = targets_parser(args, description)
+    except Exception as e:
+        print(e)
+        return 1
+
+    for target in args.TARGET:
+        # Zip the seed_corpus
+        seed_corpus = abs_join(CORPORA_DIR, "{}_seed_corpus".format(target))
+        zip_file = "{}.zip".format(seed_corpus)
+        cmd = ["zip", "-r", "-q", "-j", "-9", zip_file, "."]
+        print(' '.join(cmd))
+        subprocess.check_call(cmd, cwd=seed_corpus)
+
+
+def list_cmd(args):
+    print("\n".join(TARGETS))
+
+
+def short_help(args):
+    name = args[0]
+    print("Usage: {} [OPTIONS] COMMAND [ARGS]...\n".format(name))
+
+
+def help(args):
+    short_help(args)
+    print("\tfuzzing helpers (select a command and pass -h for help)\n")
+    print("Options:")
+    print("\t-h, --help\tPrint this message")
+    print("")
+    print("Commands:")
+    print("\tbuild\t\tBuild a fuzzer")
+    print("\tlibfuzzer\tRun a libFuzzer fuzzer")
+    print("\tafl\t\tRun an AFL fuzzer")
+    print("\tregression\tRun a regression test")
+    print("\tgen\t\tGenerate a seed corpus for a fuzzer")
+    print("\tminimize\tMinimize the test corpora")
+    print("\tzip\t\tZip the minimized corpora up")
+    print("\tlist\t\tList the available targets")
+
+
+def main():
+    args = sys.argv
+    if len(args) < 2:
+        help(args)
+        return 1
+    if args[1] == '-h' or args[1] == '--help' or args[1] == '-H':
+        help(args)
+        return 1
+    command = args.pop(1)
+    args[0] = "{} {}".format(args[0], command)
+    if command == "build":
+        return build(args)
+    if command == "libfuzzer":
+        return libfuzzer_cmd(args)
+    if command == "regression":
+        return regression(args)
+    if command == "afl":
+        return afl(args)
+    if command == "gen":
+        return gen(args)
+    if command == "minimize":
+        return minimize(args)
+    if command == "zip":
+        return zip_cmd(args)
+    if command == "list":
+        return list_cmd(args)
+    short_help(args)
+    print("Error: No such command {} (pass -h for help)".format(command))
+    return 1
+
+
+if __name__ == "__main__":
+    sys.exit(main())
diff --git a/src/zstd/tests/fuzz/fuzz_data_producer.c b/src/zstd/tests/fuzz/fuzz_data_producer.c
new file mode 100644
index 000000000..6518af309
--- /dev/null
+++ b/src/zstd/tests/fuzz/fuzz_data_producer.c
@@ -0,0 +1,84 @@
+/*
+ * Copyright (c) 2016-2020, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under both the BSD-style license (found in the
+ * LICENSE file in the root directory of this source tree) and the GPLv2 (found
+ * in the COPYING file in the root directory of this source tree).
+ * You may select, at your option, one of the above-listed licenses.
+ */
+
+#include "fuzz_data_producer.h"
+
+struct FUZZ_dataProducer_s{
+  const uint8_t *data;
+  size_t size;
+};
+
+FUZZ_dataProducer_t *FUZZ_dataProducer_create(const uint8_t *data, size_t size) {
+    FUZZ_dataProducer_t *producer = FUZZ_malloc(sizeof(FUZZ_dataProducer_t));
+
+    producer->data = data;
+    producer->size = size;
+    return producer;
+}
+
+void FUZZ_dataProducer_free(FUZZ_dataProducer_t *producer) { free(producer); }
+
+uint32_t FUZZ_dataProducer_uint32Range(FUZZ_dataProducer_t *producer, uint32_t min,
+                                  uint32_t max) {
+    FUZZ_ASSERT(min <= max);
+
+    uint32_t range = max - min;
+    uint32_t rolling = range;
+    uint32_t result = 0;
+
+    while (rolling > 0 && producer->size > 0) {
+      uint8_t next = *(producer->data + producer->size - 1);
+      producer->size -= 1;
+      result = (result << 8) | next;
+      rolling >>= 8;
+    }
+
+    if (range == 0xffffffff) {
+      return result;
+    }
+
+    return min + result % (range + 1);
+}
+
+uint32_t FUZZ_dataProducer_uint32(FUZZ_dataProducer_t *producer) {
+    return FUZZ_dataProducer_uint32Range(producer, 0, 0xffffffff);
+}
+
+int32_t FUZZ_dataProducer_int32Range(FUZZ_dataProducer_t *producer,
+                                    int32_t min, int32_t max)
+{
+    FUZZ_ASSERT(min <= max);
+
+    if (min < 0)
+      return (int)FUZZ_dataProducer_uint32Range(producer, 0, max - min) + min;
+
+    return FUZZ_dataProducer_uint32Range(producer, min, max);
+}
+
+size_t FUZZ_dataProducer_remainingBytes(FUZZ_dataProducer_t *producer){
+    return producer->size;
+}
+
+size_t FUZZ_dataProducer_contract(FUZZ_dataProducer_t *producer, size_t newSize)
+{
+    newSize = newSize > producer->size ? producer->size : newSize;
+
+    size_t remaining = producer->size - newSize;
+    producer->data = producer->data + remaining;
+    producer->size = newSize;
+    return remaining;
+}
+
+size_t FUZZ_dataProducer_reserveDataPrefix(FUZZ_dataProducer_t *producer)
+{
+    size_t producerSliceSize = FUZZ_dataProducer_uint32Range(
+                                  producer, 0, producer->size);
+    return FUZZ_dataProducer_contract(producer, producerSliceSize);
+}
diff --git a/src/zstd/tests/fuzz/fuzz_data_producer.h b/src/zstd/tests/fuzz/fuzz_data_producer.h
new file mode 100644
index 000000000..41e0b52d5
--- /dev/null
+++ b/src/zstd/tests/fuzz/fuzz_data_producer.h
@@ -0,0 +1,61 @@
+/*
+ * Copyright (c) 2016-2020, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under both the BSD-style license (found in the
+ * LICENSE file in the root directory of this source tree) and the GPLv2 (found
+ * in the COPYING file in the root directory of this source tree).
+ * You may select, at your option, one of the above-listed licenses.
+ */
+
+/**
+ * Helper APIs for generating random data from input data stream.
+ The producer reads bytes from the end of the input and appends them together
+ to generate  a random number in the requested range. If it runs out of input
+ data, it will keep returning the same value (min) over and over again.
+
+ */
+
+#ifndef FUZZ_DATA_PRODUCER_H
+#define FUZZ_DATA_PRODUCER_H
+
+#include <stddef.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "fuzz_helpers.h"
+
+/* Struct used for maintaining the state of the data */
+typedef struct FUZZ_dataProducer_s FUZZ_dataProducer_t;
+
+/* Returns a data producer state struct. Use for producer initialization. */
+FUZZ_dataProducer_t *FUZZ_dataProducer_create(const uint8_t *data, size_t size);
+
+/* Frees the data producer */
+void FUZZ_dataProducer_free(FUZZ_dataProducer_t *producer);
+
+/* Returns value between [min, max] */
+uint32_t FUZZ_dataProducer_uint32Range(FUZZ_dataProducer_t *producer, uint32_t min,
+                                  uint32_t max);
+
+/* Returns a uint32 value */
+uint32_t FUZZ_dataProducer_uint32(FUZZ_dataProducer_t *producer);
+
+/* Returns a signed value between [min, max] */
+int32_t FUZZ_dataProducer_int32Range(FUZZ_dataProducer_t *producer,
+                                    int32_t min, int32_t max);
+
+/* Returns the size of the remaining bytes of data in the producer */
+size_t FUZZ_dataProducer_remainingBytes(FUZZ_dataProducer_t *producer);
+
+/* Restricts the producer to only the last newSize bytes of data.
+If newSize > current data size, nothing happens. Returns the number of bytes
+the producer won't use anymore, after contracting. */
+size_t FUZZ_dataProducer_contract(FUZZ_dataProducer_t *producer, size_t newSize);
+
+/* Restricts the producer to use only the last X bytes of data, where X is
+ a random number in the interval [0, data_size]. Returns the size of the
+ remaining data the producer won't use anymore (the prefix). */
+size_t FUZZ_dataProducer_reserveDataPrefix(FUZZ_dataProducer_t *producer);
+#endif // FUZZ_DATA_PRODUCER_H
diff --git a/src/zstd/tests/fuzz/fuzz_helpers.c b/src/zstd/tests/fuzz/fuzz_helpers.c
new file mode 100644
index 000000000..b80dc7571
--- /dev/null
+++ b/src/zstd/tests/fuzz/fuzz_helpers.c
@@ -0,0 +1,32 @@
+/*
+ * Copyright (c) 2016-2020, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under both the BSD-style license (found in the
+ * LICENSE file in the root directory of this source tree) and the GPLv2 (found
+ * in the COPYING file in the root directory of this source tree).
+ * You may select, at your option, one of the above-listed licenses.
+ */
+#include "fuzz_helpers.h"
+
+#include <stddef.h>
+#include <stdlib.h>
+#include <string.h>
+
+void* FUZZ_malloc(size_t size)
+{
+    if (size > 0) {
+        void* const mem = malloc(size);
+        FUZZ_ASSERT(mem);
+        return mem;
+    }
+    return NULL;
+}
+
+int FUZZ_memcmp(void const* lhs, void const* rhs, size_t size)
+{
+    if (size == 0) {
+        return 0;
+    }
+    return memcmp(lhs, rhs, size);
+}
\ No newline at end of file
diff --git a/src/zstd/tests/fuzz/fuzz_helpers.h b/src/zstd/tests/fuzz/fuzz_helpers.h
new file mode 100644
index 000000000..cde2c4ea7
--- /dev/null
+++ b/src/zstd/tests/fuzz/fuzz_helpers.h
@@ -0,0 +1,74 @@
+/*
+ * Copyright (c) 2016-2020, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under both the BSD-style license (found in the
+ * LICENSE file in the root directory of this source tree) and the GPLv2 (found
+ * in the COPYING file in the root directory of this source tree).
+ * You may select, at your option, one of the above-listed licenses.
+ */
+
+/**
+ * Helper functions for fuzzing.
+ */
+
+#ifndef FUZZ_HELPERS_H
+#define FUZZ_HELPERS_H
+
+#include "debug.h"
+#include "fuzz.h"
+#include "xxhash.h"
+#include "zstd.h"
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#define MIN(a, b) ((a) < (b) ? (a) : (b))
+#define MAX(a, b) ((a) > (b) ? (a) : (b))
+
+#define FUZZ_QUOTE_IMPL(str) #str
+#define FUZZ_QUOTE(str) FUZZ_QUOTE_IMPL(str)
+
+/**
+ * Asserts for fuzzing that are always enabled.
+ */
+#define FUZZ_ASSERT_MSG(cond, msg)                                             \
+  ((cond) ? (void)0                                                            \
+          : (fprintf(stderr, "%s: %u: Assertion: `%s' failed. %s\n", __FILE__, \
+                     __LINE__, FUZZ_QUOTE(cond), (msg)),                       \
+             abort()))
+#define FUZZ_ASSERT(cond) FUZZ_ASSERT_MSG((cond), "");
+#define FUZZ_ZASSERT(code)                                                     \
+  FUZZ_ASSERT_MSG(!ZSTD_isError(code), ZSTD_getErrorName(code))
+
+#if defined(__GNUC__)
+#define FUZZ_STATIC static __inline __attribute__((unused))
+#elif defined(__cplusplus) ||                                                  \
+    (defined(__STDC_VERSION__) && (__STDC_VERSION__ >= 199901L) /* C99 */)
+#define FUZZ_STATIC static inline
+#elif defined(_MSC_VER)
+#define FUZZ_STATIC static __inline
+#else
+#define FUZZ_STATIC static
+#endif
+
+/**
+ * malloc except return NULL for zero sized data and FUZZ_ASSERT
+ * that malloc doesn't fail.
+ */
+void* FUZZ_malloc(size_t size);
+
+/**
+ * memcmp but accepts NULL.
+ */
+int FUZZ_memcmp(void const* lhs, void const* rhs, size_t size);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
diff --git a/src/zstd/tests/fuzz/raw_dictionary_round_trip.c b/src/zstd/tests/fuzz/raw_dictionary_round_trip.c
new file mode 100644
index 000000000..08e5fd9ed
--- /dev/null
+++ b/src/zstd/tests/fuzz/raw_dictionary_round_trip.c
@@ -0,0 +1,115 @@
+/*
+ * Copyright (c) 2016-2020, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under both the BSD-style license (found in the
+ * LICENSE file in the root directory of this source tree) and the GPLv2 (found
+ * in the COPYING file in the root directory of this source tree).
+ * You may select, at your option, one of the above-listed licenses.
+ */
+
+/**
+ * This fuzz target performs a zstd round-trip test (compress & decompress) with
+ * a raw content dictionary, compares the result with the original, and calls
+ * abort() on corruption.
+ */
+
+#include <stddef.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include "fuzz_helpers.h"
+#include "zstd_helpers.h"
+#include "fuzz_data_producer.h"
+
+static ZSTD_CCtx *cctx = NULL;
+static ZSTD_DCtx *dctx = NULL;
+
+static size_t roundTripTest(void *result, size_t resultCapacity,
+                            void *compressed, size_t compressedCapacity,
+                            const void *src, size_t srcSize,
+                            const void *dict, size_t dictSize,
+                            FUZZ_dataProducer_t *producer)
+{
+    ZSTD_dictContentType_e const dictContentType = ZSTD_dct_rawContent;
+    int const refPrefix = FUZZ_dataProducer_uint32Range(producer, 0, 1) != 0;
+    size_t cSize;
+
+    FUZZ_setRandomParameters(cctx, srcSize, producer);
+    /* Disable checksum so we can use sizes smaller than compress bound. */
+    FUZZ_ZASSERT(ZSTD_CCtx_setParameter(cctx, ZSTD_c_checksumFlag, 0));
+    if (refPrefix)
+        FUZZ_ZASSERT(ZSTD_CCtx_refPrefix_advanced(
+            cctx, dict, dictSize,
+            ZSTD_dct_rawContent));
+    else 
+        FUZZ_ZASSERT(ZSTD_CCtx_loadDictionary_advanced(
+            cctx, dict, dictSize,
+            (ZSTD_dictLoadMethod_e)FUZZ_dataProducer_uint32Range(producer, 0, 1),
+            ZSTD_dct_rawContent));
+    cSize = ZSTD_compress2(cctx, compressed, compressedCapacity, src, srcSize);
+    FUZZ_ZASSERT(cSize);
+
+    if (refPrefix)
+        FUZZ_ZASSERT(ZSTD_DCtx_refPrefix_advanced(
+            dctx, dict, dictSize,
+            dictContentType));
+    else
+        FUZZ_ZASSERT(ZSTD_DCtx_loadDictionary_advanced(
+            dctx, dict, dictSize,
+            (ZSTD_dictLoadMethod_e)FUZZ_dataProducer_uint32Range(producer, 0, 1),
+            dictContentType));
+    {
+        size_t const ret = ZSTD_decompressDCtx(
+                dctx, result, resultCapacity, compressed, cSize);
+        return ret;
+    }
+}
+
+int LLVMFuzzerTestOneInput(const uint8_t *src, size_t 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 = FUZZ_dataProducer_reserveDataPrefix(producer);
+
+    uint8_t const* const srcBuf = src;
+    size_t const srcSize = FUZZ_dataProducer_uint32Range(producer, 0, size);
+    uint8_t const* const dictBuf = srcBuf + srcSize;
+    size_t const dictSize = size - srcSize;
+    size_t const decompSize = srcSize;
+    void* const decompBuf = FUZZ_malloc(decompSize);
+    size_t compSize = ZSTD_compressBound(srcSize);
+    void* compBuf;
+    /* Half of the time fuzz with a 1 byte smaller output size.
+     * This will still succeed because we force the checksum to be disabled,
+     * giving us 4 bytes of overhead.
+     */
+    compSize -= FUZZ_dataProducer_uint32Range(producer, 0, 1);
+    compBuf = FUZZ_malloc(compSize);
+
+    if (!cctx) {
+        cctx = ZSTD_createCCtx();
+        FUZZ_ASSERT(cctx);
+    }
+    if (!dctx) {
+        dctx = ZSTD_createDCtx();
+        FUZZ_ASSERT(dctx);
+    }
+
+    {
+        size_t const result =
+            roundTripTest(decompBuf, decompSize, compBuf, compSize, srcBuf, srcSize, dictBuf, dictSize, producer);
+        FUZZ_ZASSERT(result);
+        FUZZ_ASSERT_MSG(result == srcSize, "Incorrect regenerated size");
+        FUZZ_ASSERT_MSG(!FUZZ_memcmp(src, decompBuf, srcSize), "Corruption!");
+    }
+    free(decompBuf);
+    free(compBuf);
+    FUZZ_dataProducer_free(producer);
+#ifndef STATEFUL_FUZZING
+    ZSTD_freeCCtx(cctx); cctx = NULL;
+    ZSTD_freeDCtx(dctx); dctx = NULL;
+#endif
+    return 0;
+}
diff --git a/src/zstd/tests/fuzz/regression_driver.c b/src/zstd/tests/fuzz/regression_driver.c
new file mode 100644
index 000000000..8180ca822
--- /dev/null
+++ b/src/zstd/tests/fuzz/regression_driver.c
@@ -0,0 +1,89 @@
+/*
+ * Copyright (c) 2016-2020, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under both the BSD-style license (found in the
+ * LICENSE file in the root directory of this source tree) and the GPLv2 (found
+ * in the COPYING file in the root directory of this source tree).
+ * You may select, at your option, one of the above-listed licenses.
+ */
+
+#include "fuzz.h"
+#include "fuzz_helpers.h"
+#include "util.h"
+#include <stddef.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+int main(int argc, char const **argv) {
+  size_t const kMaxFileSize = (size_t)1 << 27;
+  int const kFollowLinks = 1;
+  FileNamesTable* files;
+  const char** const fnTable = argv + 1;
+  uint8_t *buffer = NULL;
+  size_t bufferSize = 0;
+  unsigned i;
+  unsigned numFilesTested = 0;
+  int ret = 0;
+
+  {
+    unsigned const numFiles = (unsigned)(argc - 1);
+#ifdef UTIL_HAS_CREATEFILELIST
+    files = UTIL_createExpandedFNT(fnTable, numFiles, kFollowLinks);
+#else
+    files = UTIL_createFNT_fromROTable(fnTable, numFiles);
+    assert(numFiles == files->tableSize);
+#endif
+  }
+  if (!files) {
+    fprintf(stderr, "ERROR: Failed to create file names table\n");
+    return 1;
+  }
+  if (files->tableSize == 0)
+    fprintf(stderr, "WARNING: No files passed to %s\n", argv[0]);
+  for (i = 0; i < files->tableSize; ++i) {
+    char const *fileName = files->fileNames[i];
+    DEBUGLOG(3, "Running %s", fileName);
+    size_t const fileSize = UTIL_getFileSize(fileName);
+    size_t readSize;
+    FILE *file;
+
+    /* Check that it is a regular file, and that the fileSize is valid.
+     * If it is not a regular file, then it may have been deleted since we
+     * constructed the list, so just skip it, but return an error exit code.
+     */
+    if (!UTIL_isRegularFile(fileName)) {
+      ret = 1;
+      continue;
+    }
+    FUZZ_ASSERT_MSG(fileSize <= kMaxFileSize, fileName);
+    /* Ensure we have a large enough buffer allocated */
+    if (fileSize > bufferSize) {
+      free(buffer);
+      buffer = (uint8_t *)malloc(fileSize);
+      FUZZ_ASSERT_MSG(buffer, fileName);
+      bufferSize = fileSize;
+    }
+    /* Open the file */
+    file = fopen(fileName, "rb");
+    FUZZ_ASSERT_MSG(file, fileName);
+    /* Read the file */
+    readSize = fread(buffer, 1, fileSize, file);
+    FUZZ_ASSERT_MSG(readSize == fileSize, fileName);
+    /* Close the file */
+    fclose(file);
+    /* Run the fuzz target */
+    LLVMFuzzerTestOneInput(buffer, fileSize);
+    ++numFilesTested;
+  }
+  fprintf(stderr, "Tested %u files: ", numFilesTested);
+  if (ret == 0) {
+    fprintf(stderr, "Success!\n");
+  } else {
+    fprintf(stderr, "Failure!\n");
+  }
+  free(buffer);
+  UTIL_freeFileNamesTable(files);
+  return ret;
+}
diff --git a/src/zstd/tests/fuzz/simple_compress.c b/src/zstd/tests/fuzz/simple_compress.c
new file mode 100644
index 000000000..b64f373eb
--- /dev/null
+++ b/src/zstd/tests/fuzz/simple_compress.c
@@ -0,0 +1,52 @@
+/*
+ * Copyright (c) 2016-2020, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under both the BSD-style license (found in the
+ * LICENSE file in the root directory of this source tree) and the GPLv2 (found
+ * in the COPYING file in the root directory of this source tree).
+ * You may select, at your option, one of the above-listed licenses.
+ */
+
+/**
+ * This fuzz target attempts to comprss the fuzzed data with the simple
+ * compression function with an output buffer that may be too small to
+ * ensure that the compressor never crashes.
+ */
+
+#include <stddef.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include "fuzz_helpers.h"
+#include "zstd.h"
+#include "zstd_helpers.h"
+#include "fuzz_data_producer.h"
+
+static ZSTD_CCtx *cctx = NULL;
+
+int LLVMFuzzerTestOneInput(const uint8_t *src, size_t 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 = FUZZ_dataProducer_reserveDataPrefix(producer);
+
+    size_t const maxSize = ZSTD_compressBound(size);
+    size_t const bufSize = FUZZ_dataProducer_uint32Range(producer, 0, maxSize);
+
+    int const cLevel = FUZZ_dataProducer_int32Range(producer, kMinClevel, kMaxClevel);
+
+    if (!cctx) {
+        cctx = ZSTD_createCCtx();
+        FUZZ_ASSERT(cctx);
+    }
+
+    void *rBuf = FUZZ_malloc(bufSize);
+    ZSTD_compressCCtx(cctx, rBuf, bufSize, src, size, cLevel);
+    free(rBuf);
+    FUZZ_dataProducer_free(producer);
+#ifndef STATEFUL_FUZZING
+    ZSTD_freeCCtx(cctx); cctx = NULL;
+#endif
+    return 0;
+}
diff --git a/src/zstd/tests/fuzz/simple_decompress.c b/src/zstd/tests/fuzz/simple_decompress.c
new file mode 100644
index 000000000..c3903ce8b
--- /dev/null
+++ b/src/zstd/tests/fuzz/simple_decompress.c
@@ -0,0 +1,49 @@
+/*
+ * Copyright (c) 2016-2020, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under both the BSD-style license (found in the
+ * LICENSE file in the root directory of this source tree) and the GPLv2 (found
+ * in the COPYING file in the root directory of this source tree).
+ * You may select, at your option, one of the above-listed licenses.
+ */
+
+/**
+ * This fuzz target attempts to decompress the fuzzed data with the simple
+ * decompression function to ensure the decompressor never crashes.
+ */
+
+#include <stddef.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include "fuzz_helpers.h"
+#include "zstd.h"
+#include "fuzz_data_producer.h"
+
+static ZSTD_DCtx *dctx = NULL;
+
+int LLVMFuzzerTestOneInput(const uint8_t *src, size_t 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 = FUZZ_dataProducer_reserveDataPrefix(producer);
+
+    if (!dctx) {
+        dctx = ZSTD_createDCtx();
+        FUZZ_ASSERT(dctx);
+    }
+
+    size_t const bufSize = FUZZ_dataProducer_uint32Range(producer, 0, 10 * size);
+    void *rBuf = FUZZ_malloc(bufSize);
+
+    ZSTD_decompressDCtx(dctx, rBuf, bufSize, src, size);
+    free(rBuf);
+
+    FUZZ_dataProducer_free(producer);
+
+#ifndef STATEFUL_FUZZING
+    ZSTD_freeDCtx(dctx); dctx = NULL;
+#endif
+    return 0;
+}
diff --git a/src/zstd/tests/fuzz/simple_round_trip.c b/src/zstd/tests/fuzz/simple_round_trip.c
new file mode 100644
index 000000000..2f008d06a
--- /dev/null
+++ b/src/zstd/tests/fuzz/simple_round_trip.c
@@ -0,0 +1,114 @@
+/*
+ * Copyright (c) 2016-2020, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under both the BSD-style license (found in the
+ * LICENSE file in the root directory of this source tree) and the GPLv2 (found
+ * in the COPYING file in the root directory of this source tree).
+ * You may select, at your option, one of the above-listed licenses.
+ */
+
+/**
+ * This fuzz target performs a zstd round-trip test (compress & decompress),
+ * compares the result with the original, and calls abort() on corruption.
+ */
+
+#define ZSTD_STATIC_LINKING_ONLY
+
+#include <stddef.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include "fuzz_helpers.h"
+#include "zstd_helpers.h"
+#include "fuzz_data_producer.h"
+
+static ZSTD_CCtx *cctx = NULL;
+static ZSTD_DCtx *dctx = NULL;
+
+static size_t roundTripTest(void *result, size_t resultCapacity,
+                            void *compressed, size_t compressedCapacity,
+                            const void *src, size_t srcSize,
+                            FUZZ_dataProducer_t *producer)
+{
+    size_t cSize;
+    size_t dSize;
+    int targetCBlockSize = 0;
+    if (FUZZ_dataProducer_uint32Range(producer, 0, 1)) {
+        FUZZ_setRandomParameters(cctx, srcSize, producer);
+        cSize = ZSTD_compress2(cctx, compressed, compressedCapacity, src, srcSize);
+        FUZZ_ZASSERT(ZSTD_CCtx_getParameter(cctx, ZSTD_c_targetCBlockSize, &targetCBlockSize));
+    } else {
+      int const cLevel = FUZZ_dataProducer_int32Range(producer, kMinClevel, kMaxClevel);
+
+        cSize = ZSTD_compressCCtx(
+            cctx, compressed, compressedCapacity, src, srcSize, cLevel);
+    }
+    FUZZ_ZASSERT(cSize);
+    dSize = ZSTD_decompressDCtx(dctx, result, resultCapacity, compressed, cSize);
+    FUZZ_ZASSERT(dSize);
+    /* When superblock is enabled make sure we don't expand the block more than expected. */
+    if (targetCBlockSize != 0) {
+        size_t normalCSize;
+        FUZZ_ZASSERT(ZSTD_CCtx_setParameter(cctx, ZSTD_c_targetCBlockSize, 0));
+        normalCSize = ZSTD_compress2(cctx, compressed, compressedCapacity, src, srcSize);
+        FUZZ_ZASSERT(normalCSize);
+        {
+            size_t const bytesPerBlock = 3 /* block header */
+                + 5 /* Literal header */
+                + 6 /* Huffman jump table */
+                + 3 /* number of sequences */
+                + 1 /* symbol compression modes */;
+            size_t const expectedExpansion = bytesPerBlock * (1 + (normalCSize / MAX(1, targetCBlockSize)));
+            size_t const allowedExpansion = (srcSize >> 3) + 5 * expectedExpansion + 10;
+            FUZZ_ASSERT(cSize <= normalCSize + allowedExpansion);
+        }
+    }
+    return dSize;
+}
+
+int LLVMFuzzerTestOneInput(const uint8_t *src, size_t size)
+{
+    size_t const rBufSize = size;
+    void* rBuf = FUZZ_malloc(rBufSize);
+    size_t cBufSize = ZSTD_compressBound(size);
+    void* cBuf;
+
+    /* 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 = FUZZ_dataProducer_reserveDataPrefix(producer);
+
+    /* Half of the time fuzz with a 1 byte smaller output size.
+     * This will still succeed because we don't use a dictionary, so the dictID
+     * field is empty, giving us 4 bytes of overhead.
+     */
+    cBufSize -= FUZZ_dataProducer_uint32Range(producer, 0, 1);
+
+    cBuf = FUZZ_malloc(cBufSize);
+
+    if (!cctx) {
+        cctx = ZSTD_createCCtx();
+        FUZZ_ASSERT(cctx);
+    }
+    if (!dctx) {
+        dctx = ZSTD_createDCtx();
+        FUZZ_ASSERT(dctx);
+    }
+
+    {
+        size_t const result =
+            roundTripTest(rBuf, rBufSize, cBuf, cBufSize, src, size, producer);
+        FUZZ_ZASSERT(result);
+        FUZZ_ASSERT_MSG(result == size, "Incorrect regenerated size");
+        FUZZ_ASSERT_MSG(!FUZZ_memcmp(src, rBuf, size), "Corruption!");
+    }
+    free(rBuf);
+    free(cBuf);
+    FUZZ_dataProducer_free(producer);
+#ifndef STATEFUL_FUZZING
+    ZSTD_freeCCtx(cctx); cctx = NULL;
+    ZSTD_freeDCtx(dctx); dctx = NULL;
+#endif
+    return 0;
+}
diff --git a/src/zstd/tests/fuzz/stream_decompress.c b/src/zstd/tests/fuzz/stream_decompress.c
new file mode 100644
index 000000000..25901b1eb
--- /dev/null
+++ b/src/zstd/tests/fuzz/stream_decompress.c
@@ -0,0 +1,116 @@
+/*
+ * Copyright (c) 2016-2020, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under both the BSD-style license (found in the
+ * LICENSE file in the root directory of this source tree) and the GPLv2 (found
+ * in the COPYING file in the root directory of this source tree).
+ * You may select, at your option, one of the above-listed licenses.
+ */
+
+/**
+ * This fuzz target attempts to decompress the fuzzed data with the simple
+ * decompression function to ensure the decompressor never crashes.
+ */
+
+#define ZSTD_STATIC_LINKING_ONLY
+
+#include <stddef.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include "fuzz_helpers.h"
+#include "zstd.h"
+#include "fuzz_data_producer.h"
+
+static size_t const kBufSize = ZSTD_BLOCKSIZE_MAX;
+
+static ZSTD_DStream *dstream = NULL;
+static void* buf = NULL;
+uint32_t seed;
+
+static ZSTD_outBuffer makeOutBuffer(FUZZ_dataProducer_t *producer, uint32_t min)
+{
+  ZSTD_outBuffer buffer = { buf, 0, 0 };
+
+  buffer.size = (FUZZ_dataProducer_uint32Range(producer, min, kBufSize));
+  FUZZ_ASSERT(buffer.size <= kBufSize);
+
+  if (buffer.size == 0) {
+    buffer.dst = NULL;
+  }
+
+  return buffer;
+}
+
+static ZSTD_inBuffer makeInBuffer(const uint8_t **src, size_t *size,
+                                  FUZZ_dataProducer_t *producer,
+                                  uint32_t min)
+{
+  ZSTD_inBuffer buffer = { *src, 0, 0 };
+
+  FUZZ_ASSERT(*size > 0);
+  buffer.size = (FUZZ_dataProducer_uint32Range(producer, min, *size));
+  FUZZ_ASSERT(buffer.size <= *size);
+  *src += buffer.size;
+  *size -= buffer.size;
+
+  if (buffer.size == 0) {
+    buffer.src = NULL;
+  }
+
+  return buffer;
+}
+
+int LLVMFuzzerTestOneInput(const uint8_t *src, size_t 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);
+    /* Guarantee forward progress by refusing to generate 2 zero sized
+     * buffers in a row. */
+    int prevInWasZero = 0;
+    int prevOutWasZero = 0;
+    int stableOutBuffer;
+    ZSTD_outBuffer out;
+    size = FUZZ_dataProducer_reserveDataPrefix(producer);
+
+    /* Allocate all buffers and contexts if not already allocated */
+    if (!buf) {
+        buf = FUZZ_malloc(kBufSize);
+    }
+
+    if (!dstream) {
+        dstream = ZSTD_createDStream();
+        FUZZ_ASSERT(dstream);
+    } else {
+        FUZZ_ZASSERT(ZSTD_DCtx_reset(dstream, ZSTD_reset_session_only));
+    }
+
+    stableOutBuffer = FUZZ_dataProducer_uint32Range(producer, 0, 10) == 5;
+    if (stableOutBuffer) {
+      FUZZ_ZASSERT(ZSTD_DCtx_setParameter(dstream, ZSTD_d_stableOutBuffer, 1));
+      out.dst = buf;
+      out.size = kBufSize;
+      out.pos = 0;
+    }
+
+    while (size > 0) {
+        ZSTD_inBuffer in = makeInBuffer(&src, &size, producer, prevInWasZero ? 1 : 0);
+        prevInWasZero = in.size == 0;
+        while (in.pos != in.size) {
+            if (!stableOutBuffer || prevOutWasZero || FUZZ_dataProducer_uint32Range(producer, 0, 100) == 55) {
+              out = makeOutBuffer(producer, prevOutWasZero ? 1 : 0);
+            }
+            prevOutWasZero = out.size == 0;
+            size_t const rc = ZSTD_decompressStream(dstream, &out, &in);
+            if (ZSTD_isError(rc)) goto error;
+        }
+    }
+
+error:
+#ifndef STATEFUL_FUZZING
+    ZSTD_freeDStream(dstream); dstream = NULL;
+#endif
+    FUZZ_dataProducer_free(producer);
+    return 0;
+}
diff --git a/src/zstd/tests/fuzz/stream_round_trip.c b/src/zstd/tests/fuzz/stream_round_trip.c
new file mode 100644
index 000000000..286d3871b
--- /dev/null
+++ b/src/zstd/tests/fuzz/stream_round_trip.c
@@ -0,0 +1,177 @@
+/*
+ * Copyright (c) 2016-2020, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under both the BSD-style license (found in the
+ * LICENSE file in the root directory of this source tree) and the GPLv2 (found
+ * in the COPYING file in the root directory of this source tree).
+ * You may select, at your option, one of the above-listed licenses.
+ */
+
+/**
+ * This fuzz target performs a zstd round-trip test (compress & decompress),
+ * compares the result with the original, and calls abort() on corruption.
+ */
+
+#define ZSTD_STATIC_LINKING_ONLY
+
+#include <stddef.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include "fuzz_helpers.h"
+#include "zstd_helpers.h"
+#include "fuzz_data_producer.h"
+
+ZSTD_CCtx *cctx = NULL;
+static ZSTD_DCtx *dctx = NULL;
+static uint8_t* cBuf = NULL;
+static uint8_t* rBuf = NULL;
+static size_t bufSize = 0;
+
+static ZSTD_outBuffer makeOutBuffer(uint8_t *dst, size_t capacity,
+                                    FUZZ_dataProducer_t *producer)
+{
+    ZSTD_outBuffer buffer = { dst, 0, 0 };
+
+    FUZZ_ASSERT(capacity > 0);
+    buffer.size = (FUZZ_dataProducer_uint32Range(producer, 1, capacity));
+    FUZZ_ASSERT(buffer.size <= capacity);
+
+    return buffer;
+}
+
+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_dataProducer_uint32Range(producer, 1, *size));
+    FUZZ_ASSERT(buffer.size <= *size);
+    *src += buffer.size;
+    *size -= buffer.size;
+
+    return buffer;
+}
+
+static size_t compress(uint8_t *dst, size_t capacity,
+                       const uint8_t *src, size_t srcSize,
+                     FUZZ_dataProducer_t *producer)
+{
+    size_t dstSize = 0;
+    ZSTD_CCtx_reset(cctx, ZSTD_reset_session_only);
+    FUZZ_setRandomParameters(cctx, srcSize, producer);
+
+    while (srcSize > 0) {
+        ZSTD_inBuffer in = makeInBuffer(&src, &srcSize, producer);
+        /* Mode controls the action. If mode == -1 we pick a new mode */
+        int mode = -1;
+        while (in.pos < in.size || mode != -1) {
+            ZSTD_outBuffer out = makeOutBuffer(dst, capacity, producer);
+            /* Previous action finished, pick a new mode. */
+            if (mode == -1) mode = FUZZ_dataProducer_uint32Range(producer, 0, 9);
+            switch (mode) {
+                case 0: /* fall-through */
+                case 1: /* fall-through */
+                case 2: {
+                    size_t const ret =
+                        ZSTD_compressStream2(cctx, &out, &in, ZSTD_e_flush);
+                    FUZZ_ZASSERT(ret);
+                    if (ret == 0)
+                        mode = -1;
+                    break;
+                }
+                case 3: {
+                    size_t ret =
+                        ZSTD_compressStream2(cctx, &out, &in, ZSTD_e_end);
+                    FUZZ_ZASSERT(ret);
+                    /* Reset the compressor when the frame is finished */
+                    if (ret == 0) {
+                        ZSTD_CCtx_reset(cctx, ZSTD_reset_session_only);
+                        if (FUZZ_dataProducer_uint32Range(producer, 0, 7) == 0) {
+                            size_t const remaining = in.size - in.pos;
+                            FUZZ_setRandomParameters(cctx, remaining, producer);
+                        }
+                        mode = -1;
+                    }
+                    break;
+                }
+                case 4: {
+                    ZSTD_inBuffer nullIn = { NULL, 0, 0 };
+                    ZSTD_outBuffer nullOut = { NULL, 0, 0 };
+                    size_t const ret = ZSTD_compressStream2(cctx, &nullOut, &nullIn, ZSTD_e_continue);
+                    FUZZ_ZASSERT(ret);
+                }
+                /* fall-through */
+                default: {
+                    size_t const ret =
+                        ZSTD_compressStream2(cctx, &out, &in, ZSTD_e_continue);
+                    FUZZ_ZASSERT(ret);
+                    mode = -1;
+                }
+            }
+            dst += out.pos;
+            dstSize += out.pos;
+            capacity -= out.pos;
+        }
+    }
+    for (;;) {
+        ZSTD_inBuffer in = {NULL, 0, 0};
+        ZSTD_outBuffer out = makeOutBuffer(dst, capacity, producer);
+        size_t const ret = ZSTD_compressStream2(cctx, &out, &in, ZSTD_e_end);
+        FUZZ_ZASSERT(ret);
+
+        dst += out.pos;
+        dstSize += out.pos;
+        capacity -= out.pos;
+        if (ret == 0)
+            break;
+    }
+    return dstSize;
+}
+
+int LLVMFuzzerTestOneInput(const uint8_t *src, size_t size)
+{
+    size_t neededBufSize;
+
+    /* 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 = FUZZ_dataProducer_reserveDataPrefix(producer);
+
+    neededBufSize = ZSTD_compressBound(size) * 15;
+
+    /* Allocate all buffers and contexts if not already allocated */
+    if (neededBufSize > bufSize) {
+        free(cBuf);
+        free(rBuf);
+        cBuf = (uint8_t*)FUZZ_malloc(neededBufSize);
+        rBuf = (uint8_t*)FUZZ_malloc(neededBufSize);
+        bufSize = neededBufSize;
+    }
+    if (!cctx) {
+        cctx = ZSTD_createCCtx();
+        FUZZ_ASSERT(cctx);
+    }
+    if (!dctx) {
+        dctx = ZSTD_createDCtx();
+        FUZZ_ASSERT(dctx);
+    }
+
+    {
+        size_t const cSize = compress(cBuf, neededBufSize, src, size, producer);
+        size_t const rSize =
+            ZSTD_decompressDCtx(dctx, rBuf, neededBufSize, cBuf, cSize);
+        FUZZ_ZASSERT(rSize);
+        FUZZ_ASSERT_MSG(rSize == size, "Incorrect regenerated size");
+        FUZZ_ASSERT_MSG(!FUZZ_memcmp(src, rBuf, size), "Corruption!");
+    }
+
+    FUZZ_dataProducer_free(producer);
+#ifndef STATEFUL_FUZZING
+    ZSTD_freeCCtx(cctx); cctx = NULL;
+    ZSTD_freeDCtx(dctx); dctx = NULL;
+#endif
+    return 0;
+}
diff --git a/src/zstd/tests/fuzz/zstd_frame_info.c b/src/zstd/tests/fuzz/zstd_frame_info.c
new file mode 100644
index 000000000..876a74e9a
--- /dev/null
+++ b/src/zstd/tests/fuzz/zstd_frame_info.c
@@ -0,0 +1,43 @@
+/*
+ * Copyright (c) 2016-2020, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under both the BSD-style license (found in the
+ * LICENSE file in the root directory of this source tree) and the GPLv2 (found
+ * in the COPYING file in the root directory of this source tree).
+ * You may select, at your option, one of the above-listed licenses.
+ */
+
+/**
+ * This fuzz target fuzzes all of the helper functions that consume compressed
+ * input.
+ */
+
+#include <stddef.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include "fuzz_helpers.h"
+#include "zstd_helpers.h"
+
+int LLVMFuzzerTestOneInput(const uint8_t *src, size_t size)
+{
+    ZSTD_frameHeader zfh;
+    if (size == 0) {
+        src = NULL;
+   }
+    /* You can fuzz any helper functions here that are fast, and take zstd
+     * compressed data as input. E.g. don't expect the input to be a dictionary,
+     * so don't fuzz ZSTD_getDictID_fromDict().
+     */
+    ZSTD_getFrameContentSize(src, size);
+    ZSTD_getDecompressedSize(src, size);
+    ZSTD_findFrameCompressedSize(src, size);
+    ZSTD_getDictID_fromFrame(src, size);
+    ZSTD_findDecompressedSize(src, size);
+    ZSTD_decompressBound(src, size);
+    ZSTD_frameHeaderSize(src, size);
+    ZSTD_isFrame(src, size);
+    ZSTD_getFrameHeader(&zfh, src, size);
+    ZSTD_getFrameHeader_advanced(&zfh, src, size, ZSTD_f_zstd1);
+    return 0;
+}
diff --git a/src/zstd/tests/fuzz/zstd_helpers.c b/src/zstd/tests/fuzz/zstd_helpers.c
new file mode 100644
index 000000000..5680bd628
--- /dev/null
+++ b/src/zstd/tests/fuzz/zstd_helpers.c
@@ -0,0 +1,145 @@
+/*
+ * Copyright (c) 2016-2020, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under both the BSD-style license (found in the
+ * LICENSE file in the root directory of this source tree) and the GPLv2 (found
+ * in the COPYING file in the root directory of this source tree).
+ * You may select, at your option, one of the above-listed licenses.
+ */
+
+#define ZSTD_STATIC_LINKING_ONLY
+#define ZDICT_STATIC_LINKING_ONLY
+
+#include <string.h>
+
+#include "zstd_helpers.h"
+#include "fuzz_helpers.h"
+#include "zstd.h"
+#include "zdict.h"
+
+const int kMinClevel = -3;
+const int kMaxClevel = 19;
+
+static void set(ZSTD_CCtx *cctx, ZSTD_cParameter param, int value)
+{
+    FUZZ_ZASSERT(ZSTD_CCtx_setParameter(cctx, param, value));
+}
+
+static void setRand(ZSTD_CCtx *cctx, ZSTD_cParameter param, unsigned min,
+                    unsigned max, FUZZ_dataProducer_t *producer) {
+    unsigned const value = FUZZ_dataProducer_uint32Range(producer, min, max);
+    set(cctx, param, value);
+}
+
+ZSTD_compressionParameters FUZZ_randomCParams(size_t srcSize, FUZZ_dataProducer_t *producer)
+{
+    /* Select compression parameters */
+    ZSTD_compressionParameters cParams;
+    cParams.windowLog = FUZZ_dataProducer_uint32Range(producer, ZSTD_WINDOWLOG_MIN, 15);
+    cParams.hashLog = FUZZ_dataProducer_uint32Range(producer, ZSTD_HASHLOG_MIN, 15);
+    cParams.chainLog = FUZZ_dataProducer_uint32Range(producer, ZSTD_CHAINLOG_MIN, 16);
+    cParams.searchLog = FUZZ_dataProducer_uint32Range(producer, ZSTD_SEARCHLOG_MIN, 9);
+    cParams.minMatch = FUZZ_dataProducer_uint32Range(producer, ZSTD_MINMATCH_MIN,
+                                          ZSTD_MINMATCH_MAX);
+    cParams.targetLength = FUZZ_dataProducer_uint32Range(producer, 0, 512);
+    cParams.strategy = FUZZ_dataProducer_uint32Range(producer, ZSTD_STRATEGY_MIN, ZSTD_STRATEGY_MAX);
+    return ZSTD_adjustCParams(cParams, srcSize, 0);
+}
+
+ZSTD_frameParameters FUZZ_randomFParams(FUZZ_dataProducer_t *producer)
+{
+    /* Select frame parameters */
+    ZSTD_frameParameters fParams;
+    fParams.contentSizeFlag = FUZZ_dataProducer_uint32Range(producer, 0, 1);
+    fParams.checksumFlag = FUZZ_dataProducer_uint32Range(producer, 0, 1);
+    fParams.noDictIDFlag = FUZZ_dataProducer_uint32Range(producer, 0, 1);
+    return fParams;
+}
+
+ZSTD_parameters FUZZ_randomParams(size_t srcSize, FUZZ_dataProducer_t *producer)
+{
+    ZSTD_parameters params;
+    params.cParams = FUZZ_randomCParams(srcSize, producer);
+    params.fParams = FUZZ_randomFParams(producer);
+    return params;
+}
+
+void FUZZ_setRandomParameters(ZSTD_CCtx *cctx, size_t srcSize, FUZZ_dataProducer_t *producer)
+{
+    ZSTD_compressionParameters cParams = FUZZ_randomCParams(srcSize, producer);
+    set(cctx, ZSTD_c_windowLog, cParams.windowLog);
+    set(cctx, ZSTD_c_hashLog, cParams.hashLog);
+    set(cctx, ZSTD_c_chainLog, cParams.chainLog);
+    set(cctx, ZSTD_c_searchLog, cParams.searchLog);
+    set(cctx, ZSTD_c_minMatch, cParams.minMatch);
+    set(cctx, ZSTD_c_targetLength, cParams.targetLength);
+    set(cctx, ZSTD_c_strategy, cParams.strategy);
+    /* Select frame parameters */
+    setRand(cctx, ZSTD_c_contentSizeFlag, 0, 1, producer);
+    setRand(cctx, ZSTD_c_checksumFlag, 0, 1, producer);
+    setRand(cctx, ZSTD_c_dictIDFlag, 0, 1, producer);
+    /* Select long distance matching parameters */
+    setRand(cctx, ZSTD_c_enableLongDistanceMatching, 0, 1, producer);
+    setRand(cctx, ZSTD_c_ldmHashLog, ZSTD_HASHLOG_MIN, 16, producer);
+    setRand(cctx, ZSTD_c_ldmMinMatch, ZSTD_LDM_MINMATCH_MIN,
+            ZSTD_LDM_MINMATCH_MAX, producer);
+    setRand(cctx, ZSTD_c_ldmBucketSizeLog, 0, ZSTD_LDM_BUCKETSIZELOG_MAX,
+            producer);
+    setRand(cctx, ZSTD_c_ldmHashRateLog, ZSTD_LDM_HASHRATELOG_MIN,
+            ZSTD_LDM_HASHRATELOG_MAX, producer);
+    /* Set misc parameters */
+    setRand(cctx, ZSTD_c_nbWorkers, 0, 2, producer);
+    setRand(cctx, ZSTD_c_rsyncable, 0, 1, producer);
+    setRand(cctx, ZSTD_c_forceMaxWindow, 0, 1, producer);
+    setRand(cctx, ZSTD_c_literalCompressionMode, 0, 2, producer);
+    setRand(cctx, ZSTD_c_forceAttachDict, 0, 2, producer);
+    if (FUZZ_dataProducer_uint32Range(producer, 0, 1) == 0) {
+      setRand(cctx, ZSTD_c_srcSizeHint, ZSTD_SRCSIZEHINT_MIN, 2 * srcSize, producer);
+    }
+    if (FUZZ_dataProducer_uint32Range(producer, 0, 1) == 0) {
+      setRand(cctx, ZSTD_c_targetCBlockSize, ZSTD_TARGETCBLOCKSIZE_MIN, ZSTD_TARGETCBLOCKSIZE_MAX, producer);
+    }
+}
+
+FUZZ_dict_t FUZZ_train(void const* src, size_t srcSize, FUZZ_dataProducer_t *producer)
+{
+    size_t const dictSize = MAX(srcSize / 8, 1024);
+    size_t const totalSampleSize = dictSize * 11;
+    FUZZ_dict_t dict = { FUZZ_malloc(dictSize), dictSize };
+    char* const samples = (char*)FUZZ_malloc(totalSampleSize);
+    unsigned nbSamples = 100;
+    size_t* const samplesSizes = (size_t*)FUZZ_malloc(sizeof(size_t) * nbSamples);
+    size_t pos = 0;
+    size_t sample = 0;
+    ZDICT_fastCover_params_t params;
+
+    for (sample = 0; sample < nbSamples; ++sample) {
+      size_t const remaining = totalSampleSize - pos;
+      size_t const offset = FUZZ_dataProducer_uint32Range(producer, 0, MAX(srcSize, 1) - 1);
+      size_t const limit = MIN(srcSize - offset, remaining);
+      size_t const toCopy = MIN(limit, remaining / (nbSamples - sample));
+      memcpy(samples + pos, src + offset, toCopy);
+      pos += toCopy;
+      samplesSizes[sample] = toCopy;
+    }
+    memset(samples + pos, 0, totalSampleSize - pos);
+
+    memset(&params, 0, sizeof(params));
+    params.accel = 5;
+    params.k = 40;
+    params.d = 8;
+    params.f = 14;
+    params.zParams.compressionLevel = 1;
+    dict.size = ZDICT_trainFromBuffer_fastCover(dict.buff, dictSize,
+        samples, samplesSizes, nbSamples, params);
+    if (ZSTD_isError(dict.size)) {
+        free(dict.buff);
+        memset(&dict, 0, sizeof(dict));
+    }
+
+    free(samplesSizes);
+    free(samples);
+
+    return dict;
+}
diff --git a/src/zstd/tests/fuzz/zstd_helpers.h b/src/zstd/tests/fuzz/zstd_helpers.h
new file mode 100644
index 000000000..6a4e340d3
--- /dev/null
+++ b/src/zstd/tests/fuzz/zstd_helpers.h
@@ -0,0 +1,51 @@
+/*
+ * Copyright (c) 2016-2020, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under both the BSD-style license (found in the
+ * LICENSE file in the root directory of this source tree) and the GPLv2 (found
+ * in the COPYING file in the root directory of this source tree).
+ * You may select, at your option, one of the above-listed licenses.
+ */
+/**
+ * Helper functions for fuzzing.
+ */
+
+#ifndef ZSTD_HELPERS_H
+#define ZSTD_HELPERS_H
+
+#define ZSTD_STATIC_LINKING_ONLY
+
+#include "zstd.h"
+#include "fuzz_data_producer.h"
+#include <stdint.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+extern const int kMinClevel;
+extern const int kMaxClevel;
+
+void FUZZ_setRandomParameters(ZSTD_CCtx *cctx, size_t srcSize, FUZZ_dataProducer_t *producer);
+
+ZSTD_compressionParameters FUZZ_randomCParams(size_t srcSize, FUZZ_dataProducer_t *producer);
+ZSTD_frameParameters FUZZ_randomFParams(FUZZ_dataProducer_t *producer);
+ZSTD_parameters FUZZ_randomParams(size_t srcSize, FUZZ_dataProducer_t *producer);
+
+typedef struct {
+  void* buff;
+  size_t size;
+} FUZZ_dict_t;
+
+/* Quickly train a dictionary from a source for fuzzing.
+ * NOTE: Don't use this to train production dictionaries, it is only optimized
+ * for speed, and doesn't care about dictionary quality.
+ */
+FUZZ_dict_t FUZZ_train(void const* src, size_t srcSize, FUZZ_dataProducer_t *producer);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* ZSTD_HELPERS_H */