Add fuzz target for sha512_256

hashes/fuzz/Cargo.toml

@@ -40,6 +40,10 @@ path = "fuzz_targets/sha256.rs"
 name = "sha512"
 path = "fuzz_targets/sha512.rs"
 
+[[bin]]
+name = "sha512_256"
+path = "fuzz_targets/sha512_256.rs"
+
 [[bin]]
 name = "cbor"
 path = "fuzz_targets/cbor.rs"

hashes/fuzz/fuzz_targets/sha512_256.rs

@@ -0,0 +1,57 @@
+
+extern crate bitcoin_hashes;
+extern crate crypto;
+
+use bitcoin_hashes::Hash;
+use bitcoin_hashes::sha512_256;
+use crypto::digest::Digest;
+use crypto::sha2::Sha512Trunc256;
+
+fn do_test(data: &[u8]) {
+    let our_hash = sha512_256::Hash::hash(data);
+
+    let mut rc_hash = [0u8; 32];
+    let mut rc_engine = Sha512Trunc256::new();
+    rc_engine.input(data);
+    rc_engine.result(&mut rc_hash);
+
+    assert_eq!(&our_hash[..], &rc_hash[..]);
+}
+
+#[cfg(feature = "honggfuzz")]
+#[macro_use]
+extern crate honggfuzz;
+
+#[cfg(feature = "honggfuzz")]
+fn main() {
+    loop {
+        fuzz!(|d| { do_test(d) });
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    fn extend_vec_from_hex(hex: &str, out: &mut Vec<u8>) {
+        let mut b = 0;
+        for (idx, c) in hex.as_bytes().iter().enumerate() {
+            b <<= 4;
+            match *c {
+                b'A'...b'F' => b |= c - b'A' + 10,
+                b'a'...b'f' => b |= c - b'a' + 10,
+                b'0'...b'9' => b |= c - b'0',
+                _ => panic!("Bad hex"),
+            }
+            if (idx & 1) == 1 {
+                out.push(b);
+                b = 0;
+            }
+        }
+    }
+
+    #[test]
+    fn duplicate_crash() {
+        let mut a = Vec::new();
+        extend_vec_from_hex("00000", &mut a);
+        super::do_test(&a);
+    }
+}