test(fuzz): read -> write bson (#500)

Author: tristan-f-r

fuzz/Cargo.toml

@@ -27,4 +27,8 @@ path = "fuzz_targets/iterate.rs"
 
 [[bin]]
 name = "raw_deserialize"
-path = "fuzz_targets/raw_deserialize.rs"
+path = "fuzz_targets/raw_deserialize.rs"
+
+[[bin]]
+name = "raw_deserialize_utf8_lossy"
+path = "fuzz_targets/raw_deserialize_utf8_lossy.rs"

fuzz/fuzz_targets/deserialize.rs

@@ -1,10 +1,14 @@
 #![no_main]
-#[macro_use] extern crate libfuzzer_sys;
+#[macro_use]
+extern crate libfuzzer_sys;
 extern crate bson;
 
 use bson::Document;
 use std::io::Cursor;
 
 fuzz_target!(|buf: &[u8]| {
-    let _ = Document::from_reader(&mut Cursor::new(&buf[..]));
+    if let Ok(doc) = Document::from_reader(&mut Cursor::new(&buf[..])) {
+        let mut vec = Vec::with_capacity(buf.len());
+        let _ = doc.to_writer(&mut vec);
+    }
 });

fuzz/fuzz_targets/iterate.rs

@@ -1,5 +1,6 @@
 #![no_main]
-#[macro_use] extern crate libfuzzer_sys;
+#[macro_use]
+extern crate libfuzzer_sys;
 extern crate bson;
 use bson::RawDocument;
 

fuzz/fuzz_targets/raw_deserialize.rs

@@ -1,8 +1,12 @@
 #![no_main]
-#[macro_use] extern crate libfuzzer_sys;
+#[macro_use]
+extern crate libfuzzer_sys;
 extern crate bson;
 use bson::Document;
 
 fuzz_target!(|buf: &[u8]| {
-    let _ = bson::from_slice::<Document>(buf);
+    if let Ok(doc) = bson::from_slice::<Document>(buf) {
+        let mut vec = Vec::with_capacity(buf.len());
+        let _ = doc.to_writer(&mut vec);
+    }
 });

fuzz/fuzz_targets/raw_deserialize_utf8_lossy.rs

@@ -0,0 +1,11 @@
+#![no_main]
+#[macro_use] extern crate libfuzzer_sys;
+extern crate bson;
+use bson::Document;
+
+fuzz_target!(|buf: &[u8]| {
+    if let Ok(doc) = bson::from_slice_utf8_lossy::<Document>(buf) {
+        let mut vec = Vec::with_capacity(buf.len());
+        let _ = doc.to_writer(&mut vec);
+    }
+});