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 16namespace lldb_private { 17 18/// An abstract interface for things that know how to map numeric user/group IDs 19/// into names. It caches the resolved names to avoid repeating expensive 20/// queries. The cache is internally protected by a mutex, so concurrent queries 21/// are safe. 22class UserIDResolver { 23public: 24 typedef uint32_t id_t; 25 virtual ~UserIDResolver(); // anchor 26 27 llvm::Optional<llvm::StringRef> GetUserName(id_t uid) { 28 return Get(uid, m_uid_cache, &UserIDResolver::DoGetUserName); 29 } 30 llvm::Optional<llvm::StringRef> GetGroupName(id_t gid) { 31 return Get(gid, m_gid_cache, &UserIDResolver::DoGetGroupName); 32 } 33 34 /// Returns a resolver which returns a failure value for each query. Useful as 35 /// a fallback value for the case when we know all lookups will fail. 36 static UserIDResolver &GetNoopResolver(); 37 38protected: 39 virtual llvm::Optional<std::string> DoGetUserName(id_t uid) = 0; 40 virtual llvm::Optional<std::string> DoGetGroupName(id_t gid) = 0; 41 42private: 43 using Map = llvm::DenseMap<id_t, llvm::Optional<std::string>>; 44 45 llvm::Optional<llvm::StringRef> 46 Get(id_t id, Map &cache, 47 llvm::Optional<std::string> (UserIDResolver::*do_get)(id_t)); 48 49 std::mutex m_mutex; 50 Map m_uid_cache; 51 Map m_gid_cache; 52}; 53 54} // namespace lldb_private 55 56#endif // #ifndef LLDB_HOST_USERIDRESOLVER_H 57