From 1e1f5d6d5c9c3bc9aa19cabb4c47f7ee1bd7d33a Mon Sep 17 00:00:00 2001
From: Andrew Noyes <andrew@weaselab.dev>
Date: Thu, 16 May 2024 17:29:02 -0700
Subject: [PATCH] Add FacadeFuzz

---
 CMakeLists.txt   |   6 +++
 FacadeFuzz.cpp   | 107 +++++++++++++++++++++++++++++++++++++++++++++++
 KeyCompare.h     |  18 ++++++++
 VersionedMap.cpp |  12 +-----
 4 files changed, 132 insertions(+), 11 deletions(-)
 create mode 100644 FacadeFuzz.cpp
 create mode 100644 KeyCompare.h

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 6828322..304f6eb 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -156,6 +156,12 @@ if(BUILD_TESTING)
                                              ${TEST_FLAGS})
   target_link_options(facade_test PRIVATE -fsanitize=address,undefined)
 
+  add_executable(facade_fuzz FacadeFuzz.cpp)
+  target_link_libraries(facade_fuzz PRIVATE ${PROJECT_NAME})
+  target_compile_options(facade_fuzz PRIVATE -fsanitize=address,undefined,fuzzer
+                                             ${TEST_FLAGS})
+  target_link_options(facade_fuzz PRIVATE -fsanitize=address,undefined,fuzzer)
+
   # symbol visibility tests
   if(NOT CMAKE_BUILD_TYPE STREQUAL Debug)
     if(APPLE)
diff --git a/FacadeFuzz.cpp b/FacadeFuzz.cpp
new file mode 100644
index 0000000..e985f6c
--- /dev/null
+++ b/FacadeFuzz.cpp
@@ -0,0 +1,107 @@
+#include "Facade.h"
+#include "Internal.h"
+#include "KeyCompare.h"
+
+#include <map>
+#include <set>
+
+#define DEBUG 0
+
+constexpr int kKeySize = 4;
+
+weaselab::VersionedMap::Key randomKey(Arena &arena) {
+  auto *result = new (arena) uint8_t[kKeySize];
+  gRandom.randomHex(result, kKeySize);
+  return {result, kKeySize};
+}
+
+weaselab::VersionedMap::Key arbitraryKey(Arena &arena) {
+  auto *result = new (arena) uint8_t[kKeySize];
+  gArbitrary.randomHex(result, kKeySize);
+  return {result, kKeySize};
+}
+
+struct KeyComp {
+  bool operator()(const weaselab::VersionedMap::Key &lhs,
+                  const weaselab::VersionedMap::Key &rhs) const {
+    return lhs < rhs;
+  }
+};
+
+extern "C" int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
+  initFuzz(data, size);
+
+  Facade facade{0};
+  Arena arena;
+
+  while (gArbitrary.hasEntropy()) {
+    switch (gArbitrary.bounded(3)) {
+    case 0: {
+      // Add mutations
+
+      const int numKeys = gArbitrary.bounded(10);
+      std::set<weaselab::VersionedMap::Key, KeyComp> keySet;
+      while (int(keySet.size()) < numKeys) {
+        keySet.insert(randomKey(arena));
+      }
+      std::vector<weaselab::VersionedMap::Key> keys;
+      keys.insert(keys.end(), keySet.begin(), keySet.end());
+      std::vector<weaselab::VersionedMap::Mutation> mutations;
+      for (int i = 0; i < int(keys.size());) {
+        switch (gArbitrary.bounded(3)) {
+        case 0: {
+          // Point write
+          auto val = randomKey(arena);
+          mutations.push_back({keys[i].p, val.p, keys[i].len, val.len,
+                               weaselab::VersionedMap::Set});
+          ++i;
+        } break;
+        case 1: {
+          // Point clear
+          mutations.push_back({keys[i].p, nullptr, keys[i].len, 0,
+                               weaselab::VersionedMap::Clear});
+          ++i;
+        } break;
+        case 2: {
+          // Range clear
+          if (i + 1 < int(keys.size())) {
+            mutations.push_back({keys[i].p, keys[i + 1].p, keys[i].len,
+                                 keys[i + 1].len,
+                                 weaselab::VersionedMap::Clear});
+            i += 2;
+          }
+        } break;
+        }
+      }
+
+      facade.addMutations(mutations.data(), mutations.size(),
+                          facade.getVersion() + 1);
+
+    } break;
+    case 1: {
+      // Set oldest version
+
+      facade.setOldestVersion(facade.getOldestVersion() +
+                              gArbitrary.bounded(facade.getVersion() -
+                                                 facade.getOldestVersion() +
+                                                 1));
+    } break;
+    case 2: {
+      // Check range read
+
+      const int64_t version = facade.getOldestVersion() +
+                              gArbitrary.bounded(facade.getVersion() -
+                                                 facade.getOldestVersion() + 1);
+      auto begin = arbitraryKey(arena);
+      auto end = arbitraryKey(arena);
+      const int limit = gArbitrary.bounded(100000);
+      const bool reverse = gArbitrary.bounded(2);
+
+      facade.viewAt(version).rangeRead(String(begin.p, begin.len),
+                                       String(end.p, end.len), limit, reverse);
+    } break;
+    }
+  }
+
+  return 0;
+}
\ No newline at end of file
diff --git a/KeyCompare.h b/KeyCompare.h
new file mode 100644
index 0000000..74478ba
--- /dev/null
+++ b/KeyCompare.h
@@ -0,0 +1,18 @@
+#pragma once
+
+#include "VersionedMap.h"
+
+#include <algorithm>
+#include <string.h>
+
+inline auto operator<=>(const weaselab::VersionedMap::Key &lhs,
+                        const weaselab::VersionedMap::Key &rhs) {
+  int cl = std::min(lhs.len, rhs.len);
+  if (cl > 0) {
+    int c = memcmp(lhs.p, rhs.p, cl);
+    if (c != 0) {
+      return c <=> 0;
+    }
+  }
+  return lhs.len <=> rhs.len;
+}
diff --git a/VersionedMap.cpp b/VersionedMap.cpp
index b88fb89..9dfe71e 100644
--- a/VersionedMap.cpp
+++ b/VersionedMap.cpp
@@ -1,5 +1,6 @@
 #include "VersionedMap.h"
 #include "Internal.h"
+#include "KeyCompare.h"
 #include "RootSet.h"
 
 #include <assert.h>
@@ -390,17 +391,6 @@ auto operator<=>(const VersionedMap::Key &lhs, const Node &rhs) {
   return lhs.len <=> rhs.entry->keyLen;
 }
 
-auto operator<=>(const VersionedMap::Key &lhs, const VersionedMap::Key &rhs) {
-  int cl = std::min(lhs.len, rhs.len);
-  if (cl > 0) {
-    int c = memcmp(lhs.p, rhs.p, cl);
-    if (c != 0) {
-      return c <=> 0;
-    }
-  }
-  return lhs.len <=> rhs.len;
-}
-
 constexpr int orderToInt(std::strong_ordering o) {
   return o == std::strong_ordering::less    ? -1
          : o == std::strong_ordering::equal ? 0