1//===-- UserIDResolver.h ----------------------------------------*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9#ifndef LLDB_UTILITY_USERIDRESOLVER_H
10#define LLDB_UTILITY_USERIDRESOLVER_H
11
12#include "llvm/ADT/DenseMap.h"
13#include "llvm/ADT/StringRef.h"
14#include <mutex>
15#include <optional>
16
17namespace lldb_private {
18
19/// An abstract interface for things that know how to map numeric user/group IDs
20/// into names. It caches the resolved names to avoid repeating expensive
21/// queries. The cache is internally protected by a mutex, so concurrent queries
22/// are safe.
23class UserIDResolver {
24public:
25  typedef uint32_t id_t;
26  virtual ~UserIDResolver(); // anchor
27
28  std::optional<llvm::StringRef> GetUserName(id_t uid) {
29    return Get(uid, m_uid_cache, &UserIDResolver::DoGetUserName);
30  }
31  std::optional<llvm::StringRef> GetGroupName(id_t gid) {
32    return Get(gid, m_gid_cache, &UserIDResolver::DoGetGroupName);
33  }
34
35  /// Returns a resolver which returns a failure value for each query. Useful as
36  /// a fallback value for the case when we know all lookups will fail.
37  static UserIDResolver &GetNoopResolver();
38
39protected:
40  virtual std::optional<std::string> DoGetUserName(id_t uid) = 0;
41  virtual std::optional<std::string> DoGetGroupName(id_t gid) = 0;
42
43private:
44  using Map = llvm::DenseMap<id_t, std::optional<std::string>>;
45
46  std::optional<llvm::StringRef>
47  Get(id_t id, Map &cache,
48      std::optional<std::string> (UserIDResolver::*do_get)(id_t));
49
50  std::mutex m_mutex;
51  Map m_uid_cache;
52  Map m_gid_cache;
53};
54
55} // namespace lldb_private
56
57#endif // LLDB_UTILITY_USERIDRESOLVER_H
58