solana: Add fuzz harness for RateLimitState

Author: johnsaigle

solana/Cargo.toml

@@ -1,7 +1,7 @@
 [workspace]
 members = [
     "programs/*",
-    "modules/*"
+    "modules/*",
 ]
 resolver = "2"
 

solana/fuzz/src/Cargo.toml

@@ -1,14 +1,18 @@
 [package]
 name = "ntt-fuzz"
 version = "0.0.1"
+edition = "2021"
 
 [[bin]]
-name = "ntt-fuzz"
+name = "fuzz-trimmed-amount"
 path = "fuzz_trimmed_amount.rs"
+[[bin]]
+name = "fuzz-rate-limit-state"
+path = "fuzz_rate_limit.rs"
 
-edition = "2021"
 [dependencies]
 ntt-messages = { path = "../../modules/ntt-messages" }
+example-native-token-transfers = { path = "../../programs/example-native-token-transfers" }
 honggfuzz = "0.5"
 arbitrary = { version = "1", optional = true, features = ["derive"] }
 

solana/fuzz/src/fuzz_rate_limit.rs

@@ -0,0 +1,13 @@
+use honggfuzz::fuzz;
+use example_native_token_transfers::queue::rate_limit::RateLimitState;
+
+fn main() {
+    loop {
+         fuzz!(|input: (u64, u64)| {
+            let (limit, new_limit) = input;
+
+            let mut rls = RateLimitState::new(limit);
+            rls.set_limit(new_limit)
+        });
+    }
+}

solana/modules/ntt-messages/src/trimmed_amount.rs

@@ -61,6 +61,7 @@ impl TrimmedAmount {
             return Ok(amount);
         }
         if from_decimals > to_decimals {
+            // [`u64::checked_pow`] expects a u32 argument
             let power: u32 = (from_decimals - to_decimals).into();
             // Exponentiation will overflow u64 when `power` is greater than 18
             let scaling_factor: u64 = 10u64
@@ -69,6 +70,7 @@ impl TrimmedAmount {
 
             Ok(amount / scaling_factor)
         } else {
+            // [`u64::checked_pow`] expects a u32 argument
             let power: u32 = (to_decimals - from_decimals).into();
 
             // Exponentiation will overflow u64 when `power` is greater than 18