scripts: convert fuzzing scripts from afl-fuzz to libFuzzer

scripts/libFuzzer/.gitignore

@@ -0,0 +1 @@
+*/fuzz

scripts/libFuzzer/deflate_compress/fuzz.c

@@ -0,0 +1,52 @@
+#include <assert.h>
+#include <libdeflate.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+
+/* Fuzz the DEFLATE compression and decompression round trip. */
+int LLVMFuzzerTestOneInput(const uint8_t *in, size_t insize)
+{
+	int level;
+	bool use_bound;
+	struct libdeflate_compressor *c;
+	struct libdeflate_decompressor *d;
+	size_t csize_avail;
+	uint8_t *cbuf;
+	uint8_t *decompressed;
+	size_t csize;
+	enum libdeflate_result res;
+
+	if (insize < 2)
+		return 0;
+
+	level = in[0] % 13;
+	use_bound = in[1] % 2;
+	in += 2;
+	insize -= 2;
+
+	c = libdeflate_alloc_compressor(level);
+	d = libdeflate_alloc_decompressor();
+
+	csize_avail = use_bound ? libdeflate_deflate_compress_bound(c, insize) :
+				  insize;
+	cbuf = malloc(csize_avail);
+	decompressed = malloc(insize);
+
+	csize = libdeflate_deflate_compress(c, in, insize, cbuf, csize_avail);
+	if (csize != 0) {
+		res = libdeflate_deflate_decompress(d, cbuf, csize, decompressed,
+						    insize, NULL);
+		assert(res == LIBDEFLATE_SUCCESS);
+		assert(memcmp(in, decompressed, insize) == 0);
+	} else {
+		assert(!use_bound);
+	}
+
+	libdeflate_free_compressor(c);
+	libdeflate_free_decompressor(d);
+	free(cbuf);
+	free(decompressed);
+	return 0;
+}

scripts/libFuzzer/deflate_decompress/fuzz.c

@@ -0,0 +1,19 @@
+#include <libdeflate.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+/* Fuzz DEFLATE decompression. */
+int LLVMFuzzerTestOneInput(const uint8_t *in, size_t insize)
+{
+	size_t outsize_avail = 3 * insize;
+	uint8_t *out;
+	struct libdeflate_decompressor *d;
+
+	out = malloc(outsize_avail);
+
+	d = libdeflate_alloc_decompressor();
+	libdeflate_deflate_decompress(d, in, insize, out, outsize_avail, NULL);
+	libdeflate_free_decompressor(d);
+	free(out);
+	return 0;
+}