add crc32 fuzzer (to find memory issues)

fuzz/Cargo.toml

@@ -19,6 +19,7 @@ features = ["arbitrary-derive"]
 libc = "0.2.151"
 libz-ng-sys = "1.1.12"
 libloading = "0.8.1"
+crc32fast = "1.3.2"
 
 [dependencies.zlib-rs]
 path = "../zlib-rs"
@@ -60,3 +61,9 @@ name = "end_to_end"
 path = "fuzz_targets/end_to_end.rs"
 test = false
 doc = false
+
+[[bin]]
+name = "crc32"
+path = "fuzz_targets/crc32.rs"
+test = false
+doc = false

fuzz/fuzz_targets/crc32.rs

@@ -0,0 +1,44 @@
+#![no_main]
+
+//! the tests provide good coverage, the purose of this fuzzer is to
+//! discover memory safety issues in the SIMD implementations.
+
+use libfuzzer_sys::fuzz_target;
+
+use zlib_rs::deflate::DeflateConfig;
+use zlib_rs::inflate::InflateConfig;
+use zlib_rs::{Flush, ReturnCode};
+
+use std::ffi::{c_char, c_int, c_uint};
+
+fuzz_target!(|input: (Vec<u8>, u32)| {
+    let (input, start) = input;
+
+    {
+        let expected = {
+            let mut h = crc32fast::Hasher::new_with_initial(start);
+            h.update(&input[..]);
+            h.finalize()
+        };
+
+        let actual = zlib_rs::crc32::crc32(input.as_slice(), start);
+
+        assert_eq!(expected, actual);
+    }
+
+    {
+        let mut dst = [0; 1 << 16];
+
+        let expected = {
+            let mut h = crc32fast::Hasher::new_with_initial(0);
+            h.update(&input[..]);
+            h.finalize()
+        };
+
+        let actual = zlib_rs::crc32::crc32_copy(&mut dst[..input.len()], input.as_slice());
+
+        assert_eq!(expected, actual);
+
+        assert_eq!(input, &dst[..input.len()]);
+    }
+});