1 files changed, 71 insertions, 0 deletions
diff --git a/src/protozero/filtering/string_filter.h b/src/protozero/filtering/string_filter.h
new file mode 100644
index 000000000..eb167bdf8
--- /dev/null
+++ b/src/protozero/filtering/string_filter.h
@@ -0,0 +1,71 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ *
+ * 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 SRC_PROTOZERO_FILTERING_STRING_FILTER_H_
+#define SRC_PROTOZERO_FILTERING_STRING_FILTER_H_
+
+#include <regex>
+
+namespace protozero {
+
+// Performs filtering of strings in an "iptables" style. See the comments in
+// |TraceConfig.TraceFilter| for information on how this class works.
+class StringFilter {
+ public:
+  enum class Policy {
+    kMatchRedactGroups = 1,
+    kAtraceMatchRedactGroups = 2,
+    kMatchBreak = 3,
+    kAtraceMatchBreak = 4,
+  };
+
+  StringFilter() = default;
+
+  // Adds a new rule for filtering strings.
+  void AddRule(Policy policy,
+               std::string_view pattern,
+               std::string atrace_payload_starts_with);
+
+  // Tries to filter the given string. Returns true if the string was modified
+  // in any way, false otherwise.
+  bool MaybeFilter(char* ptr, size_t len) {
+    if (len == 0 || rules_.empty()) {
+      return false;
+    }
+    return MaybeFilterInternal(ptr, len);
+  }
+
+ private:
+  struct Rule {
+    Policy policy;
+    std::regex pattern;
+    std::string atrace_payload_starts_with;
+  };
+
+  StringFilter(StringFilter&&) noexcept = delete;
+  StringFilter& operator=(StringFilter&&) noexcept = delete;
+
+  bool MaybeFilterInternal(char* ptr, size_t len);
+
+  StringFilter(const StringFilter&) = delete;
+  StringFilter& operator=(const StringFilter&) = delete;
+
+  std::vector<Rule> rules_;
+};
+
+}  // namespace protozero
+
+#endif  // SRC_PROTOZERO_FILTERING_STRING_FILTER_H_