Add encoding parsing fuzzing

crates/objc2-encode/src/encoding_box.rs

@@ -196,4 +196,21 @@ mod tests {
         assert!(ENC3C.equivalent_to_box(&enc1));
         assert!(ENC3C.equivalent_to_box(&enc2), "now they're equivalent");
     }
+
+    #[test]
+    fn parse_atomic_struct() {
+        let expected = EncodingBox::Atomic(Box::new(EncodingBox::Atomic(Box::new(
+            EncodingBox::Struct("a".into(), Some(Vec::new())),
+        ))));
+        let actual = EncodingBox::from_str("AA{a=}").unwrap();
+        assert_eq!(expected, actual);
+        assert_eq!(expected.to_string(), "AA{a}");
+
+        let expected = EncodingBox::Atomic(Box::new(EncodingBox::Atomic(Box::new(
+            EncodingBox::Struct("a".into(), None),
+        ))));
+        let actual = EncodingBox::from_str("AA{a}").unwrap();
+        assert_eq!(expected, actual);
+        assert_eq!(expected.to_string(), "AA{a}");
+    }
 }

fuzz/.gitignore

@@ -1,2 +1,4 @@
 target/
 artifacts/
+# This grows very quickly, and doesn't really need to be in-tree
+corpus/encoding_parse/

fuzz/Cargo.toml

@@ -22,6 +22,9 @@ gnustep-1-9 = ["gnustep-1-8", "objc2/gnustep-1-9"]
 gnustep-2-0 = ["gnustep-1-9", "objc2/gnustep-2-0"]
 gnustep-2-1 = ["gnustep-2-0", "objc2/gnustep-2-1"]
 
+[workspace]
+members = ["."]
+
 [[bin]]
 name = "class"
 path = "fuzz_targets/class.rs"
@@ -34,5 +37,8 @@ path = "fuzz_targets/sel.rs"
 test = false
 doc = false
 
-[workspace]
-members = ["."]
+[[bin]]
+name = "encoding_parse"
+path = "fuzz_targets/encoding_parse.rs"
+test = false
+doc = false

fuzz/fuzz_targets/encoding_parse.rs

@@ -0,0 +1,24 @@
+#![no_main]
+use std::str::FromStr;
+
+use libfuzzer_sys::fuzz_target;
+use objc2::encode::{Encoding, EncodingBox};
+
+fuzz_target!(|s: &str| {
+    // Check that parsing encodings doesn't panic
+    if let Ok(enc) = EncodingBox::from_str(s) {
+        // Check a "negative" case of `equivalent_to_box`
+        if enc != EncodingBox::Char {
+            assert_ne!(EncodingBox::Char, enc, "not equal to char");
+            assert!(!Encoding::Char.equivalent_to_box(&enc), "not equivalent to char");
+        }
+
+        let s2 = enc.to_string();
+        // Note: s and s2 may not be equal!
+
+        // Test roundtrip
+        let enc2 = EncodingBox::from_str(&s2).expect("parsing valid encoding string");
+        let s3 = enc2.to_string();
+        assert_eq!(s2, s3);
+    }
+});