more fuzz targets

3 files changed, 51 insertions, 4 deletions

diff --git a/fuzz/Cargo.toml b/fuzz/Cargo.toml
index cf84c01..29a2307 100644
--- a/fuzz/Cargo.toml
+++ b/fuzz/Cargo.toml
@@ -18,13 +18,13 @@ yaxpeax-arch = "0.2.7"
 members = ["."]
 
 [[bin]]
-name = "fuzz_target_1"
-path = "fuzz_targets/fuzz_target_1.rs"
+name = "no-panic"
+path = "fuzz_targets/no-panic.rs"
 test = false
 doc = false
 
 [[bin]]
-name = "no-panic"
-path = "fuzz_targets/no-panic.rs"
+name = "fresh-decode"
+path = "fuzz_targets/fresh-decode.rs"
 test = false
 doc = false
diff --git a/fuzz/fuzz_targets/fresh-decode.rs b/fuzz/fuzz_targets/fresh-decode.rs
new file mode 100644
index 0000000..94664aa
--- /dev/null
+++ b/fuzz/fuzz_targets/fresh-decode.rs
@@ -0,0 +1,28 @@
+//! decoding into a pre-existing instruction should not result in different outcomes compared to
+//! decoding into a fresh instruction. if decoding succeeds, both outcomes should be equal.
+
+#![no_main]
+use libfuzzer_sys::fuzz_target;
+
+use yaxpeax_arch::Decoder;
+
+fuzz_target!(|data: &[u8]| {
+
+    let decoders = [
+        yaxpeax_rx::InstDecoder::v1(),
+        yaxpeax_rx::InstDecoder::v2(),
+        yaxpeax_rx::InstDecoder::v3(),
+    ];
+
+    let mut reused_inst = yaxpeax_rx::Instruction::default();
+
+    for decoder in decoders {
+        let mut words = yaxpeax_arch::U8Reader::new(data);
+        // test decoding, may be ok or not, but should not panic
+        if let Ok(()) = decoder.decode_into(&mut reused_inst, &mut words) {
+            let mut words = yaxpeax_arch::U8Reader::new(data);
+            let fresh_inst = decoder.decode(&mut words).expect("decoded before, can decode again");
+            assert_eq!(reused_inst, fresh_inst);
+        }
+    }
+});
diff --git a/src/lib.rs b/src/lib.rs
index 67272b0..68f0819 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -22,6 +22,25 @@ pub struct Instruction {
     length: u8,
 }
 
+impl PartialEq for Instruction {
+    fn eq(&self, other: &Self) -> bool {
+        let Instruction {
+            opcode: left_opcode,
+            operands: _, // we won't use this `operands`, but `.operands()` to not use stale extra operands
+            length: left_length,
+        } = self;
+        let Instruction {
+            opcode: right_opcode,
+            operands: _, // we won't use this `operands`, but `.operands()` to not use stale extra operands
+            length: right_length,
+        } = other;
+
+        left_opcode == right_opcode &&
+            left_length == right_length &&
+            self.operands() == other.operands()
+    }
+}
+
 impl Instruction {
     pub fn opcode(&self) -> Opcode {
         self.opcode