Setup fuzzing

.gitignore

@@ -1,2 +1,2 @@
-/target
-/Cargo.lock
+target
+Cargo.lock

fuzz/.gitignore

@@ -0,0 +1,4 @@
+target
+corpus
+artifacts
+coverage

fuzz/Cargo.toml

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+[package]
+name = "slabbin-fuzz"
+version = "0.0.0"
+publish = false
+edition = "2021"
+
+[package.metadata]
+cargo-fuzz = true
+
+[dependencies]
+arbitrary = { version = "1.0", features = ["derive_arbitrary"] }
+libfuzzer-sys = "0.4"
+
+[dependencies.slabbin]
+path = ".."
+
+# Prevent this from interfering with workspaces
+[workspace]
+members = ["."]
+
+[profile.release]
+debug = 1
+
+[[bin]]
+name = "allocate_deallocate"
+path = "fuzz_targets/allocate_deallocate.rs"
+test = false
+doc = false

fuzz/fuzz_targets/allocate_deallocate.rs

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+#![no_main]
+
+use arbitrary::Arbitrary;
+use libfuzzer_sys::fuzz_target;
+use slabbin::SlabAllocator;
+
+#[derive(Arbitrary, Debug)]
+struct Input {
+    slab_capacity: u8,
+    methods: Vec<AllocatorMethod>,
+}
+
+#[derive(Arbitrary, Debug)]
+enum AllocatorMethod {
+    Allocate,
+    Deallocate { index: usize },
+}
+
+fuzz_target!(|input: Input| {
+    if input.slab_capacity == 0 {
+        return;
+    }
+
+    let allocator = SlabAllocator::<i32>::new(usize::from(input.slab_capacity));
+    let mut ptrs = Vec::new();
+
+    for method in input.methods {
+        match method {
+            AllocatorMethod::Allocate => {
+                ptrs.push(Some(allocator.allocate()));
+            }
+            AllocatorMethod::Deallocate { index } => {
+                if let Some(&Some(ptr)) = ptrs.get(index) {
+                    unsafe { allocator.deallocate(ptr) };
+                    ptrs[index] = None;
+                }
+            }
+        }
+    }
+
+    for ptr in ptrs.into_iter().flatten() {
+        unsafe { allocator.deallocate(ptr) };
+    }
+});