GUI: Fix distributed notifications in silent mode (#936)

* WIP Rename SNTPrefixTree to PrefixTree

* WIP Implement the new PrefixTree and tests

* Add Unit type. Fix build and tests.

* lint

* Make NodeCount accessor for tests

* Updated comments

Source/common/BUILD

@@ -158,12 +158,18 @@ objc_library(
     deps = [":SNTConfigurator"],
 )
 
-cc_library(
-    name = "SNTPrefixTree",
-    srcs = ["SNTPrefixTree.cc"],
-    hdrs = ["SNTPrefixTree.h"],
-    copts = ["-std=c++11"],
-    deps = [":SNTLogging"],
+objc_library(
+    name = "PrefixTree",
+    hdrs = ["PrefixTree.h"],
+    deps = [
+        ":SNTLogging",
+        "@com_google_absl//absl/synchronization",
+    ],
+)
+
+objc_library(
+    name = "Unit",
+    hdrs = ["Unit.h"],
 )
 
 objc_library(
@@ -307,9 +313,9 @@ santa_unit_test(
 )
 
 santa_unit_test(
-    name = "SNTPrefixTreeTest",
-    srcs = ["SNTPrefixTreeTest.mm"],
-    deps = [":SNTPrefixTree"],
+    name = "PrefixTreeTest",
+    srcs = ["PrefixTreeTest.mm"],
+    deps = [":PrefixTree"],
 )
 
 santa_unit_test(
@@ -331,11 +337,11 @@ santa_unit_test(
 test_suite(
     name = "unit_tests",
     tests = [
+        ":PrefixTreeTest",
         ":SNTCachedDecisionTest",
         ":SNTFileInfoTest",
         ":SNTKVOManagerTest",
         ":SNTMetricSetTest",
-        ":SNTPrefixTreeTest",
         ":SNTRuleTest",
         ":SantaCacheTest",
     ],

Source/common/PrefixTree.h

@@ -0,0 +1,298 @@
+/// Copyright 2022 Google LLC
+///
+/// Licensed under the Apache License, Version 2.0 (the "License");
+/// you may not use this file except in compliance with the License.
+/// You may obtain a copy of the License at
+///
+///     https://www.apache.org/licenses/LICENSE-2.0
+///
+/// Unless required by applicable law or agreed to in writing, software
+/// distributed under the License is distributed on an "AS IS" BASIS,
+/// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+/// See the License for the specific language governing permissions and
+/// limitations under the License.
+
+#ifndef SANTA__COMMON__PREFIXTREE_H
+#define SANTA__COMMON__PREFIXTREE_H
+
+#include <sys/syslimits.h>
+
+#include <optional>
+
+#import "Source/common/SNTLogging.h"
+#include "absl/synchronization/mutex.h"
+
+#if SANTA_PREFIX_TREE_DEBUG
+#define DEBUG_LOG LOGD
+#else
+#define DEBUG_LOG(format, ...)  // NOP
+#endif
+
+namespace santa::common {
+
+template <typename ValueT>
+class PrefixTree {
+ private:
+  // Forward declaration
+  enum class NodeType;
+  class TreeNode;
+
+ public:
+  PrefixTree(uint32_t max_depth = PATH_MAX)
+      : root_(new TreeNode()), max_depth_(max_depth), node_count_(0) {}
+
+  ~PrefixTree() { PruneLocked(root_); }
+
+  bool InsertPrefix(const char *s, ValueT value) {
+    absl::MutexLock lock(&lock_);
+    return InsertLocked(s, value, NodeType::kPrefix);
+  }
+
+  bool InsertLiteral(const char *s, ValueT value) {
+    absl::MutexLock lock(&lock_);
+    return InsertLocked(s, value, NodeType::kLiteral);
+  }
+
+  bool HasPrefix(const char *input) {
+    absl::ReaderMutexLock lock(&lock_);
+    return HasPrefixLocked(input);
+  }
+
+  std::optional<ValueT> LookupLongestMatchingPrefix(const char *input) {
+    absl::ReaderMutexLock lock(&lock_);
+    return LookupLongestMatchingPrefixLocked(input);
+  }
+
+  void Reset() {
+    absl::MutexLock lock(&lock_);
+    PruneLocked(root_);
+    root_ = new TreeNode();
+    node_count_ = 0;
+  }
+
+#if SANTA_PREFIX_TREE_DEBUG
+  void Print() {
+    char buf[max_depth_ + 1];
+    memset(buf, 0, sizeof(buf));
+
+    absl::ReaderMutexLock lock(&lock_);
+    PrintLocked(root_, buf, 0);
+  }
+
+  uint32_t NodeCount() {
+    absl::ReaderMutexLock lock(&lock_);
+    return node_count_;
+  }
+#endif
+
+ private:
+  ABSL_EXCLUSIVE_LOCKS_REQUIRED(lock_)
+  bool InsertLocked(const char *input, ValueT value, NodeType node_type) {
+    const char *p = input;
+    TreeNode *node = root_;
+
+    while (*p) {
+      uint8_t cur_byte = (uint8_t)*p;
+
+      TreeNode *child_node = node->children_[cur_byte];
+      if (!child_node) {
+        // Current node doesn't exist...
+        // Create the rest of the nodes in the tree for the given string
+
+        // Keep a pointer to where this new branch starts from. If the
+        // input length exceeds max_depth, the new branch will need to
+        // be pruned.
+        TreeNode *branch_start_node = node;
+        uint8_t branch_start_byte = (uint8_t)*p;
+
+        do {
+          TreeNode *new_node = new TreeNode();
+          node->children_[cur_byte] = new_node;
+          node = new_node;
+          node_count_++;
+
+          // Check current depth...
+          if (p - input >= max_depth_) {
+            // Attempted to add a string that exceeded max depth
+            // Prune tree from start of this new branch
+            PruneLocked(branch_start_node->children_[branch_start_byte]);
+            branch_start_node->children_[branch_start_byte] = nullptr;
+
+            return false;
+          }
+
+          cur_byte = (uint8_t) * ++p;
+        } while (*p);
+
+        node->node_type_ = node_type;
+        node->value_ = value;
+
+        return true;
+      } else if (*(p + 1) == '\0') {
+        // Current node exists and we're at the end of our input...
+        // Note: The current node's data will be overwritten
+
+        // Only increment node count if the previous node type wasn't already a
+        // prefix or literal type (in which case it was already counted)
+        if (child_node->node_type_ == NodeType::kInner) {
+          node_count_++;
+        }
+
+        child_node->node_type_ = node_type;
+        child_node->value_ = value;
+        return true;
+      }
+
+      node = child_node;
+      p++;
+    }
+
+    // Should only get here when input is an empty string
+    return false;
+  }
+
+  ABSL_SHARED_LOCKS_REQUIRED(lock_)
+  bool HasPrefixLocked(const char *input) {
+    TreeNode *node = root_;
+    const char *p = input;
+
+    while (*p) {
+      node = node->children_[(uint8_t)*p++];
+
+      if (!node) {
+        break;
+      }
+
+      if (node->node_type_ == NodeType::kPrefix ||
+          (*p == '\0' && node->node_type_ == NodeType::kLiteral)) {
+        return true;
+      }
+    }
+
+    return false;
+  }
+
+  ABSL_SHARED_LOCKS_REQUIRED(lock_)
+  std::optional<ValueT> LookupLongestMatchingPrefixLocked(const char *input) {
+    TreeNode *node = root_;
+    TreeNode *match = nullptr;
+    const char *p = input;
+
+    while (*p) {
+      node = node->children_[(uint8_t)*p++];
+
+      if (!node) {
+        break;
+      }
+
+      if (node->node_type_ == NodeType::kPrefix ||
+          (*p == '\0' && node->node_type_ == NodeType::kLiteral)) {
+        match = node;
+      }
+    }
+
+    return match ? std::make_optional<ValueT>(match->value_) : std::nullopt;
+  }
+
+  ABSL_EXCLUSIVE_LOCKS_REQUIRED(lock_)
+  void PruneLocked(TreeNode *target) {
+    if (!target) {
+      return;
+    }
+
+    // For deep trees, a recursive approach will generate too many stack frames.
+    // Since the depth of the tree is configurable, err on the side of caution
+    // and use a "stack" to walk the tree in a non-recursive manner.
+    TreeNode **stack = new TreeNode *[node_count_ + 1];
+    if (!stack) {
+      LOGE(@"Unable to prune tree!");
+      return;
+    }
+
+    uint32_t count = 0;
+
+    // Seed the "stack" with a starting node.
+    stack[count++] = target;
+
+    // Start at the target node and walk the tree to find and delete all the
+    // sub-nodes.
+    while (count) {
+      TreeNode *node = stack[--count];
+
+      for (int i = 0; i < 256; ++i) {
+        if (!node->children_[i]) {
+          continue;
+        }
+        stack[count++] = node->children_[i];
+      }
+
+      delete node;
+      --node_count_;
+    }
+
+    delete[] stack;
+  }
+
+#if SANTA_PREFIX_TREE_DEBUG
+  ABSL_SHARED_LOCKS_REQUIRED(lock_)
+  void PrintLocked(TreeNode *node, char *buf, uint32_t depth) {
+    for (size_t i = 0; i < 256; i++) {
+      TreeNode *cur_node = node->children_[i];
+      if (cur_node) {
+        buf[depth] = i;
+        if (cur_node->node_type_ != NodeType::kInner) {
+          printf("\t%s (type: %s)\n", buf,
+                 cur_node->node_type_ == NodeType::kPrefix ? "prefix" : "literal");
+        }
+        PrintLocked(cur_node, buf, depth + 1);
+        buf[depth] = '\0';
+      }
+    }
+  }
+#endif
+
+  enum class NodeType {
+    kInner = 0,
+    kPrefix,
+    kLiteral,
+  };
+
+  ///
+  ///  TreeNode is a wrapper class that represents one byte.
+  ///  1 node can represent a whole ASCII character.
+  ///  For example a pointer to the 'A' node will be stored at children[0x41].
+  ///  It takes 1-4 nodes to represent a UTF-8 encoded Unicode character.
+  ///
+  ///  The path for "/🤘" would look like this:
+  ///      children[0x2f] -> children[0xf0] -> children[0x9f] -> children[0xa4]
+  ///      -> children[0x98]
+  ///
+  ///  The path for "/dev" is:
+  ///      children[0x2f] -> children[0x64] -> children[0x65] -> children[0x76]
+  ///
+  ///  Lookups of children are O(1).
+  ///
+  ///  Having the nodes represented by a smaller width, such as a nibble (1/2
+  ///  byte), would drastically decrease the memory footprint but would double
+  ///  required dereferences.
+  ///
+  ///  TODO(bur): Potentially convert this into a full on radix tree.
+  ///
+  class TreeNode {
+   public:
+    TreeNode() : children_(), node_type_(NodeType::kInner) {}
+    ~TreeNode() = default;
+    TreeNode *children_[256];
+    PrefixTree::NodeType node_type_;
+    ValueT value_;
+  };
+
+  TreeNode *root_;
+  const uint32_t max_depth_;
+  uint32_t node_count_ ABSL_GUARDED_BY(lock_);
+  absl::Mutex lock_;
+};
+
+}  // namespace santa::common
+
+#endif

Source/common/PrefixTreeTest.mm

@@ -0,0 +1,224 @@
+/// Copyright 2022 Google LLC
+///
+/// Licensed under the Apache License, Version 2.0 (the "License");
+/// you may not use this file except in compliance with the License.
+/// You may obtain a copy of the License at
+///
+///     https://www.apache.org/licenses/LICENSE-2.0
+///
+/// Unless required by applicable law or agreed to in writing, software
+/// distributed under the License is distributed on an "AS IS" BASIS,
+/// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+/// See the License for the specific language governing permissions and
+/// limitations under the License.
+
+#import <XCTest/XCTest.h>
+
+#define SANTA_PREFIX_TREE_DEBUG 1
+#include "Source/common/PrefixTree.h"
+
+using santa::common::PrefixTree;
+
+@interface PrefixTreeTest : XCTestCase
+@end
+
+@implementation PrefixTreeTest
+
+- (void)testBasic {
+  PrefixTree<int> tree;
+
+  XCTAssertFalse(tree.HasPrefix("/foo/bar/baz"));
+  XCTAssertFalse(tree.HasPrefix("/foo/bar.txt"));
+  XCTAssertFalse(tree.HasPrefix("/baz"));
+
+  XCTAssertTrue(tree.InsertPrefix("/foo", 12));
+  XCTAssertTrue(tree.InsertPrefix("/bar", 34));
+  XCTAssertTrue(tree.InsertLiteral("/foo/bar", 56));
+
+  // Re-inserting something that exists is allowed
+  XCTAssertTrue(tree.InsertLiteral("/foo", 78));
+  XCTAssertTrue(tree.InsertPrefix("/foo", 56));
+
+  XCTAssertTrue(tree.HasPrefix("/foo/bar/baz"));
+  XCTAssertTrue(tree.HasPrefix("/foo/bar.txt"));
+  XCTAssertFalse(tree.HasPrefix("/baz"));
+
+  // Empty strings are not supported
+  XCTAssertFalse(tree.InsertLiteral("", 0));
+  XCTAssertFalse(tree.InsertPrefix("", 0));
+}
+
+- (void)testHasPrefix {
+  PrefixTree<int> tree;
+
+  XCTAssertTrue(tree.InsertPrefix("/foo", 0));
+  XCTAssertTrue(tree.InsertLiteral("/bar", 0));
+  XCTAssertTrue(tree.InsertLiteral("/baz", 0));
+  XCTAssertTrue(tree.InsertLiteral("/qaz", 0));
+
+  // Check that a tree with a matching prefix is successful
+  XCTAssertTrue(tree.HasPrefix("/foo.txt"));
+
+  // This shouldn't succeed because `/bar` `/baz` and `qaz` are literals
+  XCTAssertFalse(tree.HasPrefix("/bar.txt"));
+  XCTAssertFalse(tree.HasPrefix("/baz.txt"));
+  XCTAssertFalse(tree.HasPrefix("/qaz.txt"));
+
+  // Now change `/bar` to a prefix type and retest HasPrefix
+  // `/bar.txt` should now succeed, but `/baz.txt` should still not pass
+  XCTAssertTrue(tree.InsertPrefix("/bar", 0));
+  XCTAssertTrue(tree.HasPrefix("/bar.txt"));
+  XCTAssertFalse(tree.HasPrefix("/baz.txt"));
+  XCTAssertFalse(tree.HasPrefix("/qaz.txt"));
+
+  // Insert a new prefix string to allow `/baz.txt` to have a valid prefix
+  XCTAssertTrue(tree.InsertPrefix("/b", 0));
+  XCTAssertTrue(tree.HasPrefix("/baz.txt"));
+  XCTAssertFalse(tree.HasPrefix("/qaz.txt"));
+
+  // An exact match on a literal allows HasPrefix to succeed
+  XCTAssertTrue(tree.InsertLiteral("/qaz.txt", 0));
+  XCTAssertTrue(tree.HasPrefix("/qaz.txt"));
+}
+
+- (void)testLookupLongestMatchingPrefix {
+  PrefixTree<int> tree;
+
+  XCTAssertTrue(tree.InsertPrefix("/foo", 12));
+  XCTAssertTrue(tree.InsertPrefix("/bar", 34));
+  XCTAssertTrue(tree.InsertPrefix("/foo/bar.txt", 56));
+
+  std::optional<int> value;
+
+  // Matching exact prefix
+  value = tree.LookupLongestMatchingPrefix("/foo");
+  XCTAssertEqual(value.value_or(0), 12);
+
+  // Ensure changing node type works as expected
+  // Literals must match exactly.
+  value = tree.LookupLongestMatchingPrefix("/foo/bar.txt.tmp");
+  XCTAssertEqual(value.value_or(0), 56);
+  XCTAssertTrue(tree.InsertLiteral("/foo/bar.txt", 90));
+  value = tree.LookupLongestMatchingPrefix("/foo/bar.txt.tmp");
+  XCTAssertEqual(value.value_or(0), 12);
+
+  // Inserting over an exiting node returns the new value
+  XCTAssertTrue(tree.InsertPrefix("/foo", 78));
+  value = tree.LookupLongestMatchingPrefix("/foo");
+  XCTAssertEqual(value.value_or(0), 78);
+
+  // No matching prefix
+  value = tree.LookupLongestMatchingPrefix("/asdf");
+  XCTAssertEqual(value.value_or(0), 0);
+}
+
+- (void)testNodeCounts {
+  const uint32_t maxDepth = 100;
+  PrefixTree<int> tree(100);
+
+  XCTAssertEqual(tree.NodeCount(), 0);
+
+  // Start with a small string
+  XCTAssertTrue(tree.InsertPrefix("asdf", 0));
+  XCTAssertEqual(tree.NodeCount(), 4);
+
+  // Add a couple more characters to the existing string
+  XCTAssertTrue(tree.InsertPrefix("asdfgh", 0));
+  XCTAssertEqual(tree.NodeCount(), 6);
+
+  // Inserting a string that exceeds max depth doesn't increase node count
+  XCTAssertFalse(tree.InsertPrefix(std::string(maxDepth + 10, 'A').c_str(), 0));
+  XCTAssertEqual(tree.NodeCount(), 6);
+
+  // Add a new string that is a prefix of an existing string
+  // This should increment the count by one since a new terminal node exists
+  XCTAssertTrue(tree.InsertPrefix("as", 0));
+  XCTAssertEqual(tree.NodeCount(), 7);
+
+  // Re-inserting onto an existing node shouldn't modify the count
+  tree.InsertLiteral("as", 0);
+  tree.InsertPrefix("as", 0);
+  XCTAssertEqual(tree.NodeCount(), 7);
+}
+
+- (void)testReset {
+  // Ensure resetting a tree removes all content
+  PrefixTree<int> tree;
+
+  tree.Reset();
+  XCTAssertEqual(tree.NodeCount(), 0);
+
+  XCTAssertTrue(tree.InsertPrefix("asdf", 0));
+  XCTAssertTrue(tree.InsertPrefix("qwerty", 0));
+
+  XCTAssertTrue(tree.HasPrefix("asdf"));
+  XCTAssertTrue(tree.HasPrefix("qwerty"));
+  XCTAssertEqual(tree.NodeCount(), 10);
+
+  tree.Reset();
+  XCTAssertFalse(tree.HasPrefix("asdf"));
+  XCTAssertFalse(tree.HasPrefix("qwerty"));
+  XCTAssertEqual(tree.NodeCount(), 0);
+}
+
+- (void)testComplexValues {
+  class Foo {
+   public:
+    Foo(int x) : x_(x) {}
+    int X() { return x_; }
+
+   private:
+    int x_;
+  };
+
+  PrefixTree<std::shared_ptr<Foo>> tree;
+
+  XCTAssertTrue(tree.InsertPrefix("foo", std::make_shared<Foo>(123)));
+  XCTAssertTrue(tree.InsertPrefix("bar", std::make_shared<Foo>(456)));
+
+  std::optional<std::shared_ptr<Foo>> value;
+  value = tree.LookupLongestMatchingPrefix("foo");
+  XCTAssertTrue(value.has_value() && value->get()->X() == 123);
+
+  value = tree.LookupLongestMatchingPrefix("bar");
+  XCTAssertTrue(value.has_value() && value->get()->X() == 456);
+
+  value = tree.LookupLongestMatchingPrefix("asdf");
+  XCTAssertFalse(value.has_value());
+}
+
+- (void)testThreading {
+  uint32_t count = 4096;
+  auto t = new PrefixTree<int>(count * (uint32_t)[NSUUID UUID].UUIDString.length);
+
+  NSMutableArray *UUIDs = [NSMutableArray arrayWithCapacity:count];
+  for (int i = 0; i < count; ++i) {
+    [UUIDs addObject:[NSUUID UUID].UUIDString];
+  }
+
+  __block BOOL stop = NO;
+
+  // Create a bunch of background noise.
+  dispatch_async(dispatch_get_global_queue(0, 0), ^{
+    for (uint64_t i = 0; i < UINT64_MAX; ++i) {
+      dispatch_async(dispatch_get_global_queue(0, 0), ^{
+        t->HasPrefix([UUIDs[i % count] UTF8String]);
+      });
+      if (stop) return;
+    }
+  });
+
+  // Fill up the tree.
+  dispatch_apply(count, dispatch_get_global_queue(0, 0), ^(size_t i) {
+    XCTAssertEqual(t->InsertPrefix([UUIDs[i] UTF8String], 0), true);
+  });
+
+  // Make sure every leaf byte is found.
+  dispatch_apply(count, dispatch_get_global_queue(0, 0), ^(size_t i) {
+    XCTAssertTrue(t->HasPrefix([UUIDs[i] UTF8String]));
+  });
+
+  stop = YES;
+}
+
+@end

Source/common/SNTPrefixTree.cc

@@ -1,227 +0,0 @@
-/// Copyright 2018 Google Inc. All rights reserved.
-///
-/// Licensed under the Apache License, Version 2.0 (the "License");
-/// you may not use this file except in compliance with the License.
-/// You may obtain a copy of the License at
-///
-///    http://www.apache.org/licenses/LICENSE-2.0
-///
-///    Unless required by applicable law or agreed to in writing, software
-///    distributed under the License is distributed on an "AS IS" BASIS,
-///    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-///    See the License for the specific language governing permissions and
-///    limitations under the License.
-
-#include "Source/common/SNTPrefixTree.h"
-
-#include <string.h>
-
-#include <mutex>
-
-#define LOGD(format, ...)  // NOP
-#define LOGE(format, ...)  // NOP
-
-#define lck_rw_lock_shared(l) pthread_rwlock_rdlock(&l)
-#define lck_rw_unlock_shared(l) pthread_rwlock_unlock(&l)
-#define lck_rw_lock_exclusive(l) pthread_rwlock_wrlock(&l)
-#define lck_rw_unlock_exclusive(l) pthread_rwlock_unlock(&l)
-
-#define lck_rw_lock_shared_to_exclusive(l) \
-  ({                                       \
-    pthread_rwlock_unlock(&l);             \
-    false;                                 \
-  })
-#define lck_rw_lock_exclusive_to_shared(l) \
-  ({                                       \
-    pthread_rwlock_unlock(&l);             \
-    pthread_rwlock_rdlock(&l);             \
-  })
-
-#define lck_mtx_lock(l) l->lock()
-#define lck_mtx_unlock(l) l->unlock()
-
-SNTPrefixTree::SNTPrefixTree(uint32_t max_nodes) {
-  root_ = new SantaPrefixNode();
-  node_count_ = 0;
-  max_nodes_ = max_nodes;
-
-  pthread_rwlock_init(&spt_lock_, nullptr);
-  spt_add_lock_ = new std::mutex;
-}
-
-IOReturn SNTPrefixTree::AddPrefix(const char *prefix, uint64_t *node_count) {
-  // Serialize requests to AddPrefix. Otherwise one AddPrefix thread could
-  // overwrite whole branches of another. HasPrefix is still free to read the
-  // tree, until AddPrefix needs to modify it.
-  lck_mtx_lock(spt_add_lock_);
-
-  // Don't allow an empty prefix.
-  if (prefix[0] == '\0') return kIOReturnBadArgument;
-
-  LOGD("Trying to add prefix: %s", prefix);
-
-  // Enforce max tree depth.
-  size_t len = strnlen(prefix, max_nodes_);
-
-  // Grab a shared lock until a new branch is required.
-  lck_rw_lock_shared(spt_lock_);
-
-  SantaPrefixNode *node = root_;
-  for (size_t i = 0; i < len; ++i) {
-    // If there is a node in the path that is considered a prefix, stop adding.
-    // For our purposes we only care about the shortest path that matches.
-    if (node->isPrefix) break;
-
-    // Only process a byte at a time.
-    uint8_t value = (uint8_t)prefix[i];
-
-    // Create the child if it does not exist.
-    if (!node->children[value]) {
-      // Upgrade the shared lock.
-      // If the upgrade fails, the shared lock is released.
-      if (!lck_rw_lock_shared_to_exclusive(spt_lock_)) {
-        // Grab a new exclusive lock.
-        lck_rw_lock_exclusive(spt_lock_);
-      }
-
-      // Is there enough room for the rest of the prefix?
-      if ((node_count_ + (len - i)) > max_nodes_) {
-        LOGE("Prefix tree is full, can not add: %s", prefix);
-
-        if (node_count) *node_count = node_count_;
-        lck_rw_unlock_exclusive(spt_lock_);
-        lck_mtx_unlock(spt_add_lock_);
-        return kIOReturnNoResources;
-      }
-
-      // Create the rest of the prefix.
-      while (i < len) {
-        value = (uint8_t)prefix[i++];
-
-        SantaPrefixNode *new_node = new SantaPrefixNode();
-        node->children[value] = new_node;
-        ++node_count_;
-
-        node = new_node;
-      }
-
-      // This is the end, mark the node as a prefix.
-      LOGD("Added prefix: %s", prefix);
-
-      node->isPrefix = true;
-
-      // Downgrade the exclusive lock
-      lck_rw_lock_exclusive_to_shared(spt_lock_);
-    } else if (i + 1 == len) {
-      // If the child does exist and it is the end...
-      // Set the new, higher prefix and prune the now dead nodes.
-
-      if (!lck_rw_lock_shared_to_exclusive(spt_lock_)) {
-        lck_rw_lock_exclusive(spt_lock_);
-      }
-
-      PruneNode(node->children[value]);
-
-      SantaPrefixNode *new_node = new SantaPrefixNode();
-      new_node->isPrefix = true;
-
-      node->children[value] = new_node;
-      ++node_count_;
-
-      LOGD("Added prefix: %s", prefix);
-
-      lck_rw_lock_exclusive_to_shared(spt_lock_);
-    }
-
-    // Get ready for the next iteration.
-    node = node->children[value];
-  }
-
-  if (node_count) *node_count = node_count_;
-
-  lck_rw_unlock_shared(spt_lock_);
-  lck_mtx_unlock(spt_add_lock_);
-
-  return kIOReturnSuccess;
-}
-
-bool SNTPrefixTree::HasPrefix(const char *string) {
-  lck_rw_lock_shared(spt_lock_);
-
-  auto found = false;
-
-  SantaPrefixNode *node = root_;
-
-  // A well formed tree will always break this loop. Even if string doesn't
-  // terminate.
-  const char *p = string;
-  while (*p) {
-    // Only process a byte at a time.
-    node = node->children[(uint8_t)*p++];
-
-    // If it doesn't exist in the tree, no match.
-    if (!node) break;
-
-    // If it does exist, is it a prefix?
-    if (node->isPrefix) {
-      found = true;
-      break;
-    }
-  }
-
-  lck_rw_unlock_shared(spt_lock_);
-
-  return found;
-}
-
-void SNTPrefixTree::Reset() {
-  lck_rw_lock_exclusive(spt_lock_);
-
-  PruneNode(root_);
-  root_ = new SantaPrefixNode();
-  node_count_ = 0;
-
-  lck_rw_unlock_exclusive(spt_lock_);
-}
-
-void SNTPrefixTree::PruneNode(SantaPrefixNode *target) {
-  if (!target) return;
-
-  // For deep trees, a recursive approach will generate too many stack frames.
-  // Make a "stack" and walk the tree.
-  auto stack = new SantaPrefixNode *[node_count_ + 1];
-  if (!stack) {
-    LOGE("Unable to prune tree!");
-
-    return;
-  }
-  auto count = 0;
-
-  // Seed the "stack" with a starting node.
-  stack[count++] = target;
-
-  // Start at the target node and walk the tree to find and delete all the
-  // sub-nodes.
-  while (count) {
-    auto node = stack[--count];
-
-    for (int i = 0; i < 256; ++i) {
-      if (!node->children[i]) continue;
-      stack[count++] = node->children[i];
-    }
-
-    delete node;
-    --node_count_;
-  }
-
-  delete[] stack;
-}
-
-SNTPrefixTree::~SNTPrefixTree() {
-  lck_rw_lock_exclusive(spt_lock_);
-  PruneNode(root_);
-  root_ = nullptr;
-  lck_rw_unlock_exclusive(spt_lock_);
-
-  pthread_rwlock_destroy(&spt_lock_);
-}

Source/common/SNTPrefixTree.h

@@ -1,91 +0,0 @@
-/// Copyright 2018 Google Inc. All rights reserved.
-///
-/// Licensed under the Apache License, Version 2.0 (the "License");
-/// you may not use this file except in compliance with the License.
-/// You may obtain a copy of the License at
-///
-///    http://www.apache.org/licenses/LICENSE-2.0
-///
-///    Unless required by applicable law or agreed to in writing, software
-///    distributed under the License is distributed on an "AS IS" BASIS,
-///    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-///    See the License for the specific language governing permissions and
-///    limitations under the License.
-
-#ifndef SANTA__SANTA_DRIVER__SANTAPREFIXTREE_H
-#define SANTA__SANTA_DRIVER__SANTAPREFIXTREE_H
-
-#include <IOKit/IOReturn.h>
-#include <sys/param.h>
-
-// Support for unit testing.
-#include <pthread.h>
-#include <stdint.h>
-
-#include <mutex>
-
-///
-///  SantaPrefixTree is a simple prefix tree implementation.
-///  Operations are thread safe.
-///
-class SNTPrefixTree {
- public:
-  // Add a prefix to the tree.
-  // Optionally pass node_count to get the number of nodes after the add.
-  IOReturn AddPrefix(const char *, uint64_t *node_count = nullptr);
-
-  // Check if the tree has a prefix for string.
-  bool HasPrefix(const char *string);
-
-  // Reset the tree.
-  void Reset();
-
-  SNTPrefixTree(uint32_t max_nodes = kDefaultMaxNodes);
-  ~SNTPrefixTree();
-
- private:
-  ///
-  ///  SantaPrefixNode is a wrapper class that represents one byte.
-  ///  1 node can represent a whole ASCII character.
-  ///  For example a pointer to the 'A' node will be stored at children[0x41].
-  ///  It takes 1-4 nodes to represent a UTF-8 encoded Unicode character.
-  ///
-  ///  The path for "/🤘" would look like this:
-  ///      children[0x2f] -> children[0xf0] -> children[0x9f] -> children[0xa4]
-  ///      -> children[0x98]
-  ///
-  ///  The path for "/dev" is:
-  ///      children[0x2f] -> children[0x64] -> children[0x65] -> children[0x76]
-  ///
-  ///  Lookups of children are O(1).
-  ///
-  ///  Having the nodes represented by a smaller width, such as a nibble (1/2
-  ///  byte), would drastically decrease the memory footprint but would double
-  ///  required dereferences.
-  ///
-  ///  TODO(bur): Potentially convert this into a full on radix tree.
-  ///
-  class SantaPrefixNode {
-   public:
-    bool isPrefix;
-    SantaPrefixNode *children[256];
-  };
-
-  // PruneNode will remove the passed in node from the tree.
-  // The passed in node and all subnodes will be deleted.
-  // It is the caller's responsibility to reset the pointer to this node (held
-  // by the parent). If the tree is in use grab the exclusive lock.
-  void PruneNode(SantaPrefixNode *);
-
-  SantaPrefixNode *root_;
-
-  // Each node takes up ~2k, assuming MAXPATHLEN is 1024 max out at ~2MB.
-  static const uint32_t kDefaultMaxNodes = MAXPATHLEN;
-  uint32_t max_nodes_;
-  uint32_t node_count_;
-
-  pthread_rwlock_t spt_lock_;
-  std::mutex *spt_add_lock_;
-};
-
-#endif /* SANTA__SANTA_DRIVER__SANTAPREFIXTREE_H */

Source/common/SNTPrefixTreeTest.mm

@@ -1,73 +0,0 @@
-/// Copyright 2018 Google Inc. All rights reserved.
-///
-/// Licensed under the Apache License, Version 2.0 (the "License");
-/// you may not use this file except in compliance with the License.
-/// You may obtain a copy of the License at
-///
-///    http://www.apache.org/licenses/LICENSE-2.0
-///
-///    Unless required by applicable law or agreed to in writing, software
-///    distributed under the License is distributed on an "AS IS" BASIS,
-///    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-///    See the License for the specific language governing permissions and
-///    limitations under the License.
-
-#import <XCTest/XCTest.h>
-
-#include "Source/common/SNTPrefixTree.h"
-
-@interface SNTPrefixTreeTest : XCTestCase
-@end
-
-@implementation SNTPrefixTreeTest
-
-- (void)testAddAndHas {
-  auto t = SNTPrefixTree();
-  XCTAssertFalse(t.HasPrefix("/private/var/tmp/file1"));
-  t.AddPrefix("/private/var/tmp/");
-  XCTAssertTrue(t.HasPrefix("/private/var/tmp/file1"));
-}
-
-- (void)testReset {
-  auto t = SNTPrefixTree();
-  t.AddPrefix("/private/var/tmp/");
-  XCTAssertTrue(t.HasPrefix("/private/var/tmp/file1"));
-  t.Reset();
-  XCTAssertFalse(t.HasPrefix("/private/var/tmp/file1"));
-}
-
-- (void)testThreading {
-  uint32_t count = 4096;
-  auto t = new SNTPrefixTree(count * (uint32_t)[NSUUID UUID].UUIDString.length);
-
-  NSMutableArray *UUIDs = [NSMutableArray arrayWithCapacity:count];
-  for (int i = 0; i < count; ++i) {
-    [UUIDs addObject:[NSUUID UUID].UUIDString];
-  }
-
-  __block BOOL stop = NO;
-
-  // Create a bunch of background noise.
-  dispatch_async(dispatch_get_global_queue(0, 0), ^{
-    for (uint64_t i = 0; i < UINT64_MAX; ++i) {
-      dispatch_async(dispatch_get_global_queue(0, 0), ^{
-        t->HasPrefix([UUIDs[i % count] UTF8String]);
-      });
-      if (stop) return;
-    }
-  });
-
-  // Fill up the tree.
-  dispatch_apply(count, dispatch_get_global_queue(0, 0), ^(size_t i) {
-    XCTAssertEqual(t->AddPrefix([UUIDs[i] UTF8String]), kIOReturnSuccess);
-  });
-
-  // Make sure every leaf byte is found.
-  dispatch_apply(count, dispatch_get_global_queue(0, 0), ^(size_t i) {
-    XCTAssertTrue(t->HasPrefix([UUIDs[i] UTF8String]));
-  });
-
-  stop = YES;
-}
-
-@end

Source/common/Unit.h

@@ -0,0 +1,24 @@
+/// Copyright 2022 Google LLC
+///
+/// Licensed under the Apache License, Version 2.0 (the "License");
+/// you may not use this file except in compliance with the License.
+/// You may obtain a copy of the License at
+///
+///     https://www.apache.org/licenses/LICENSE-2.0
+///
+/// Unless required by applicable law or agreed to in writing, software
+/// distributed under the License is distributed on an "AS IS" BASIS,
+/// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+/// See the License for the specific language governing permissions and
+/// limitations under the License.
+
+#ifndef SANTA__COMMON__UNIT_H
+#define SANTA__COMMON__UNIT_H
+
+namespace santa::common {
+
+struct Unit {};
+
+}  // namespace santa::common
+
+#endif

Source/gui/SNTNotificationManager.m

@@ -92,10 +92,16 @@ static NSString *const silencedNotificationsKey = @"SilencedNotifications";
 }
 
 - (void)queueMessage:(SNTMessageWindowController *)pendingMsg {
-  NSString *messageHash = [pendingMsg messageHash];
+  // Post a distributed notification, regardless of queue state.
+  [self postDistributedNotification:pendingMsg];
+
+  // If GUI is in silent mode or if there's already a notification queued for
+  // this message, don't do anything else.
+  if ([SNTConfigurator configurator].enableSilentMode) return;
   if ([self notificationAlreadyQueued:pendingMsg]) return;
 
-  // See if this message is silenced.
+  // See if this message has been user-silenced.
+  NSString *messageHash = [pendingMsg messageHash];
   NSUserDefaults *ud = [NSUserDefaults standardUserDefaults];
   NSDate *silenceDate = [ud objectForKey:silencedNotificationsKey][messageHash];
   if ([silenceDate isKindOfClass:[NSDate class]]) {
@@ -114,7 +120,6 @@ static NSString *const silencedNotificationsKey = @"SilencedNotifications";
 
   pendingMsg.delegate = self;
   [self.pendingNotifications addObject:pendingMsg];
-  [self postDistributedNotification:pendingMsg];
 
   if (!self.currentWindowController) {
     [self showQueuedWindow];
@@ -315,8 +320,6 @@ static NSString *const silencedNotificationsKey = @"SilencedNotifications";
 }
 
 - (void)postBlockNotification:(SNTStoredEvent *)event withCustomMessage:(NSString *)message {
-  if ([SNTConfigurator configurator].enableSilentMode) return;
-
   if (!event) {
     LOGI(@"Error: Missing event object in message received from daemon!");
     return;
@@ -329,8 +332,6 @@ static NSString *const silencedNotificationsKey = @"SilencedNotifications";
 }
 
 - (void)postUSBBlockNotification:(SNTDeviceEvent *)event withCustomMessage:(NSString *)message {
-  if ([SNTConfigurator configurator].enableSilentMode) return;
-
   if (!event) {
     LOGI(@"Error: Missing event object in message received from daemon!");
     return;

Source/santad/BUILD

@@ -245,8 +245,9 @@ objc_library(
         ":SNTCompilerController",
         ":SNTEndpointSecurityClient",
         ":SNTEndpointSecurityEventHandler",
+        "//Source/common:PrefixTree",
         "//Source/common:SNTLogging",
-        "//Source/common:SNTPrefixTree",
+        "//Source/common:Unit",
     ],
 )
 
@@ -571,13 +572,14 @@ objc_library(
         ":SNTExecutionController",
         ":SNTNotificationQueue",
         ":SNTSyncdQueue",
+        "//Source/common:PrefixTree",
         "//Source/common:SNTCommonEnums",
         "//Source/common:SNTConfigurator",
         "//Source/common:SNTKVOManager",
         "//Source/common:SNTLogging",
-        "//Source/common:SNTPrefixTree",
         "//Source/common:SNTXPCNotifierInterface",
         "//Source/common:SNTXPCSyncServiceInterface",
+        "//Source/common:Unit",
         "@MOLXPCConnection",
     ],
 )
@@ -599,12 +601,13 @@ objc_library(
         ":SNTNotificationQueue",
         ":SNTRuleTable",
         ":SNTSyncdQueue",
+        "//Source/common:PrefixTree",
         "//Source/common:SNTConfigurator",
         "//Source/common:SNTLogging",
         "//Source/common:SNTMetricSet",
-        "//Source/common:SNTPrefixTree",
         "//Source/common:SNTXPCControlInterface",
         "//Source/common:SNTXPCUnprivilegedControlInterface",
+        "//Source/common:Unit",
         "@MOLXPCConnection",
     ],
 )
@@ -1096,7 +1099,9 @@ santa_unit_test(
         ":MockEndpointSecurityAPI",
         ":SNTCompilerController",
         ":SNTEndpointSecurityRecorder",
+        "//Source/common:PrefixTree",
         "//Source/common:TestUtils",
+        "//Source/common:Unit",
         "@OCMock",
         "@com_google_googletest//:gtest",
     ],

Source/santad/EventProviders/SNTEndpointSecurityRecorder.h

@@ -12,7 +12,8 @@
 ///    See the License for the specific language governing permissions and
 ///    limitations under the License.
 
-#import "Source/common/SNTPrefixTree.h"
+#import "Source/common/PrefixTree.h"
+#import "Source/common/Unit.h"
 #import "Source/santad/EventProviders/AuthResultCache.h"
 #include "Source/santad/EventProviders/EndpointSecurity/EndpointSecurityAPI.h"
 #include "Source/santad/EventProviders/EndpointSecurity/Enricher.h"
@@ -37,6 +38,6 @@
   compilerController:(SNTCompilerController *)compilerController
      authResultCache:
        (std::shared_ptr<santa::santad::event_providers::AuthResultCache>)authResultCache
-          prefixTree:(std::shared_ptr<SNTPrefixTree>)prefixTree;
+          prefixTree:(std::shared_ptr<santa::common::PrefixTree<santa::common::Unit>>)prefixTree;
 
 @end

Source/santad/EventProviders/SNTEndpointSecurityRecorder.mm

@@ -22,6 +22,8 @@
 #include "Source/santad/EventProviders/EndpointSecurity/Message.h"
 #include "Source/santad/Metrics.h"
 
+using santa::common::PrefixTree;
+using santa::common::Unit;
 using santa::santad::EventDisposition;
 using santa::santad::event_providers::AuthResultCache;
 using santa::santad::event_providers::endpoint_security::EndpointSecurityAPI;
@@ -48,7 +50,7 @@ es_file_t *GetTargetFileForPrefixTree(const es_message_t *msg) {
   std::shared_ptr<AuthResultCache> _authResultCache;
   std::shared_ptr<Enricher> _enricher;
   std::shared_ptr<Logger> _logger;
-  std::shared_ptr<SNTPrefixTree> _prefixTree;
+  std::shared_ptr<PrefixTree<Unit>> _prefixTree;
 }
 
 - (instancetype)initWithESAPI:(std::shared_ptr<EndpointSecurityAPI>)esApi
@@ -57,7 +59,7 @@ es_file_t *GetTargetFileForPrefixTree(const es_message_t *msg) {
                      enricher:(std::shared_ptr<Enricher>)enricher
            compilerController:(SNTCompilerController *)compilerController
               authResultCache:(std::shared_ptr<AuthResultCache>)authResultCache
-                   prefixTree:(std::shared_ptr<SNTPrefixTree>)prefixTree {
+                   prefixTree:(std::shared_ptr<PrefixTree<Unit>>)prefixTree {
   self = [super initWithESAPI:std::move(esApi)
                       metrics:std::move(metrics)
                     processor:santa::santad::Processor::kRecorder];

Source/santad/EventProviders/SNTEndpointSecurityRecorderTest.mm

@@ -22,7 +22,9 @@
 #include <memory>
 #include <set>
 
+#include "Source/common/PrefixTree.h"
 #include "Source/common/TestUtils.h"
+#include "Source/common/Unit.h"
 #import "Source/santad/EventProviders/AuthResultCache.h"
 #include "Source/santad/EventProviders/EndpointSecurity/Client.h"
 #include "Source/santad/EventProviders/EndpointSecurity/EnrichedTypes.h"
@@ -34,6 +36,8 @@
 #include "Source/santad/Metrics.h"
 #import "Source/santad/SNTCompilerController.h"
 
+using santa::common::PrefixTree;
+using santa::common::Unit;
 using santa::santad::EventDisposition;
 using santa::santad::Processor;
 using santa::santad::event_providers::AuthResultCache;
@@ -116,7 +120,7 @@ class MockLogger : public Logger {
     dispatch_semaphore_signal(sema);
   }));
 
-  auto prefixTree = std::make_shared<SNTPrefixTree>();
+  auto prefixTree = std::make_shared<PrefixTree<Unit>>();
 
   id mockCC = OCMStrictClassMock([SNTCompilerController class]);
 
@@ -164,7 +168,7 @@ class MockLogger : public Logger {
   {
     esMsg.event_type = ES_EVENT_TYPE_NOTIFY_LINK;
     esMsg.event.link.source = &targetFile;
-    prefixTree->AddPrefix(esMsg.event.link.source->path.data);
+    prefixTree->InsertPrefix(esMsg.event.link.source->path.data, Unit{});
     Message msg(mockESApi, &esMsg);
 
     OCMExpect([mockCC handleEvent:msg withLogger:nullptr]).ignoringNonObjectArgs();

Source/santad/Santad.h

@@ -17,7 +17,8 @@
 
 #import <MOLXPCConnection/MOLXPCConnection.h>
 
-#include "Source/common/SNTPrefixTree.h"
+#include "Source/common/PrefixTree.h"
+#include "Source/common/Unit.h"
 #include "Source/santad/EventProviders/AuthResultCache.h"
 #include "Source/santad/EventProviders/EndpointSecurity/EndpointSecurityAPI.h"
 #include "Source/santad/EventProviders/EndpointSecurity/Enricher.h"
@@ -42,6 +43,7 @@ void SantadMain(
     SNTCompilerController* compiler_controller,
     SNTNotificationQueue* notifier_queue, SNTSyncdQueue* syncd_queue,
     SNTExecutionController* exec_controller,
-    std::shared_ptr<SNTPrefixTree> prefix_tree);
+    std::shared_ptr<santa::common::PrefixTree<santa::common::Unit>>
+        prefix_tree);
 
 #endif

Source/santad/Santad.mm

@@ -16,6 +16,7 @@
 
 #include <memory>
 
+#include "Source/common/PrefixTree.h"
 #import "Source/common/SNTCommonEnums.h"
 #import "Source/common/SNTConfigurator.h"
 #import "Source/common/SNTKVOManager.h"
@@ -32,6 +33,8 @@
 #include "Source/santad/Logs/EndpointSecurity/Logger.h"
 #include "Source/santad/SNTDaemonControlController.h"
 
+using santa::common::PrefixTree;
+using santa::common::Unit;
 using santa::santad::Metrics;
 using santa::santad::event_providers::AuthResultCache;
 using santa::santad::event_providers::FlushCacheMode;
@@ -67,7 +70,7 @@ void SantadMain(std::shared_ptr<EndpointSecurityAPI> esapi, std::shared_ptr<Logg
                 MOLXPCConnection *control_connection, SNTCompilerController *compiler_controller,
                 SNTNotificationQueue *notifier_queue, SNTSyncdQueue *syncd_queue,
                 SNTExecutionController *exec_controller,
-                std::shared_ptr<SNTPrefixTree> prefix_tree) {
+                std::shared_ptr<santa::common::PrefixTree<santa::common::Unit>> prefix_tree) {
   SNTConfigurator *configurator = [SNTConfigurator configurator];
 
   SNTDaemonControlController *dc =

Source/santad/SantadDeps.h

@@ -20,9 +20,10 @@
 
 #include <memory>
 
+#include "Source/common/PrefixTree.h"
 #include "Source/common/SNTConfigurator.h"
 #import "Source/common/SNTMetricSet.h"
-#include "Source/common/SNTPrefixTree.h"
+#include "Source/common/Unit.h"
 #include "Source/santad/EventProviders/AuthResultCache.h"
 #include "Source/santad/EventProviders/EndpointSecurity/EndpointSecurityAPI.h"
 #include "Source/santad/EventProviders/EndpointSecurity/Enricher.h"
@@ -50,7 +51,8 @@ class SantadDeps {
       SNTCompilerController *compiler_controller,
       SNTNotificationQueue *notifier_queue, SNTSyncdQueue *syncd_queue,
       SNTExecutionController *exec_controller,
-      std::shared_ptr<SNTPrefixTree> prefix_tree);
+      std::shared_ptr<santa::common::PrefixTree<santa::common::Unit>>
+          prefix_tree);
 
   std::shared_ptr<santa::santad::event_providers::AuthResultCache>
   AuthResultCache();
@@ -66,7 +68,7 @@ class SantadDeps {
   SNTNotificationQueue *NotifierQueue();
   SNTSyncdQueue *SyncdQueue();
   SNTExecutionController *ExecController();
-  std::shared_ptr<SNTPrefixTree> PrefixTree();
+  std::shared_ptr<santa::common::PrefixTree<santa::common::Unit>> PrefixTree();
 
  private:
   std::shared_ptr<
@@ -84,7 +86,7 @@ class SantadDeps {
   SNTNotificationQueue *notifier_queue_;
   SNTSyncdQueue *syncd_queue_;
   SNTExecutionController *exec_controller_;
-  std::shared_ptr<SNTPrefixTree> prefix_tree_;
+  std::shared_ptr<santa::common::PrefixTree<santa::common::Unit>> prefix_tree_;
 };
 
 }  // namespace santa::santad

Source/santad/SantadDeps.mm

@@ -23,6 +23,8 @@
 #include "Source/santad/EventProviders/EndpointSecurity/EndpointSecurityAPI.h"
 #import "Source/santad/SNTDatabaseController.h"
 
+using santa::common::PrefixTree;
+using santa::common::Unit;
 using santa::santad::Metrics;
 using santa::santad::event_providers::AuthResultCache;
 using santa::santad::event_providers::endpoint_security::EndpointSecurityAPI;
@@ -85,13 +87,13 @@ std::unique_ptr<SantadDeps> SantadDeps::Create(SNTConfigurator *configurator,
     exit(EXIT_FAILURE);
   }
 
-  std::shared_ptr<SNTPrefixTree> prefix_tree = std::make_shared<SNTPrefixTree>();
+  std::shared_ptr<::PrefixTree<Unit>> prefix_tree = std::make_shared<::PrefixTree<Unit>>();
 
   // TODO(bur): Add KVO handling for fileChangesPrefixFilters.
   NSArray<NSString *> *prefix_filters =
     [@[ @"/.", @"/dev/" ] arrayByAddingObjectsFromArray:[configurator fileChangesPrefixFilters]];
   for (NSString *filter in prefix_filters) {
-    prefix_tree->AddPrefix([filter fileSystemRepresentation]);
+    prefix_tree->InsertPrefix([filter fileSystemRepresentation], Unit {});
   }
 
   std::shared_ptr<EndpointSecurityAPI> esapi = std::make_shared<EndpointSecurityAPI>();
@@ -130,7 +132,7 @@ SantadDeps::SantadDeps(std::shared_ptr<EndpointSecurityAPI> esapi,
                        SNTCompilerController *compiler_controller,
                        SNTNotificationQueue *notifier_queue, SNTSyncdQueue *syncd_queue,
                        SNTExecutionController *exec_controller,
-                       std::shared_ptr<SNTPrefixTree> prefix_tree)
+                       std::shared_ptr<::PrefixTree<Unit>> prefix_tree)
     : esapi_(std::move(esapi)),
       logger_(std::move(logger)),
       metrics_(std::move(metrics)),
@@ -182,7 +184,7 @@ SNTExecutionController *SantadDeps::ExecController() {
   return exec_controller_;
 }
 
-std::shared_ptr<SNTPrefixTree> SantadDeps::PrefixTree() {
+std::shared_ptr<PrefixTree<Unit>> SantadDeps::PrefixTree() {
   return prefix_tree_;
 }
 

docs/development/sync-protocol.md

@@ -135,8 +135,8 @@ The JSON object has the following keys:
 | batch_size | YES | integer | Number of events to upload at a time | 128 |
 | full_sync_interval | YES | integer | Number of seconds between full syncs | 600 |
 | client_mode | YES | string | Operating mode to set for the client | either "MONITOR" or "LOCKDOWN" |
-| allowed_path_regex | YES | list of strings | List of regular expressions to allow a binary to execute from a path | ["/Users/markowsk/foo/.*"] |
-| blocked_path_regex | YES | list of strings | List of regular expressions to block a binary from executing by path | ["/tmp/"] |
+| allowed_path_regex | NO | string | Regular expression to allow a binary to execute from a path | "/Users/markowsk/foo/.*" |
+| blocked_path_regex | NO | string | Regular expression to block a binary from executing by path | "/tmp/" |
 | block_usb_mount | NO | boolean | Block USB mass storage devices | true |
 | remount_usb_mode | NO | string | Force USB mass storage devices to be remounted with the following permissions (see [configuration](../deployment/configuration.md)) |  |
 | clean_sync | YES | boolean | Whether or not the rules should be dropped and synced entirely from the server | true |