1 files changed, 56 insertions, 0 deletions
diff --git a/include/lldb/Utility/UserIDResolver.h b/include/lldb/Utility/UserIDResolver.h
new file mode 100644
index 000000000000..bca82a11b660
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+++ b/include/lldb/Utility/UserIDResolver.h
@@ -0,0 +1,56 @@
+//===-- UserIDResolver.h ----------------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLDB_UTILITY_USERIDRESOLVER_H
+#define LLDB_UTILITY_USERIDRESOLVER_H
+
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/StringRef.h"
+#include <mutex>
+
+namespace lldb_private {
+
+/// An abstract interface for things that know how to map numeric user/group IDs
+/// into names. It caches the resolved names to avoid repeating expensive
+/// queries. The cache is internally protected by a mutex, so concurrent queries
+/// are safe.
+class UserIDResolver {
+public:
+  typedef uint32_t id_t;
+  virtual ~UserIDResolver(); // anchor
+
+  llvm::Optional<llvm::StringRef> GetUserName(id_t uid) {
+    return Get(uid, m_uid_cache, &UserIDResolver::DoGetUserName);
+  }
+  llvm::Optional<llvm::StringRef> GetGroupName(id_t gid) {
+    return Get(gid, m_gid_cache, &UserIDResolver::DoGetGroupName);
+  }
+
+  /// Returns a resolver which returns a failure value for each query. Useful as
+  /// a fallback value for the case when we know all lookups will fail.
+  static UserIDResolver &GetNoopResolver();
+
+protected:
+  virtual llvm::Optional<std::string> DoGetUserName(id_t uid) = 0;
+  virtual llvm::Optional<std::string> DoGetGroupName(id_t gid) = 0;
+
+private:
+  using Map = llvm::DenseMap<id_t, llvm::Optional<std::string>>;
+
+  llvm::Optional<llvm::StringRef>
+  Get(id_t id, Map &cache,
+      llvm::Optional<std::string> (UserIDResolver::*do_get)(id_t));
+
+  std::mutex m_mutex;
+  Map m_uid_cache;
+  Map m_gid_cache;
+};
+
+} // namespace lldb_private
+
+#endif // #ifndef LLDB_HOST_USERIDRESOLVER_H