ceph/src/seastar/src/core/syscall_result.hh

   1 /*
   2  * This file is open source software, licensed to you under the terms
   3  * of the Apache License, Version 2.0 (the "License").  See the NOTICE file
   4  * distributed with this work for additional information regarding copyright
   5  * ownership.  You may not use this file except in compliance with the License.
   6  *
   7  * You may obtain a copy of the License at
   8  *
   9  *   http://www.apache.org/licenses/LICENSE-2.0
  10  *
  11  * Unless required by applicable law or agreed to in writing,
  12  * software distributed under the License is distributed on an
  13  * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
  14  * KIND, either express or implied.  See the License for the
  15  * specific language governing permissions and limitations
  16  * under the License.
  17  */
  18 /*
  19  * Copyright 2019 ScyllaDB
  20  */
  21
  22 namespace seastar {
  23
  24 namespace fs = std::filesystem;
  25
  26 #pragma once
  27 template <typename T>
  28 struct syscall_result {
  29     T result;
  30     int error;
  31     syscall_result(T result, int error) : result{std::move(result)}, error{error} {
  32     }
  33     void throw_if_error() const {
  34         if (long(result) == -1) {
  35             throw std::system_error(ec());
  36         }
  37     }
  38
  39     void throw_fs_exception(const sstring& reason, const fs::path& path) const {
  40         throw fs::filesystem_error(reason, path, ec());
  41     }
  42
  43     void throw_fs_exception(const sstring& reason, const fs::path& path1, const fs::path& path2) const {
  44         throw fs::filesystem_error(reason, path1, path2, ec());
  45     }
  46
  47     void throw_fs_exception_if_error(const sstring& reason, const sstring& path) const {
  48         if (long(result) == -1) {
  49             throw_fs_exception(reason, fs::path(path));
  50         }
  51     }
  52
  53     void throw_fs_exception_if_error(const sstring& reason, const sstring& path1, const sstring& path2) const {
  54         if (long(result) == -1) {
  55             throw_fs_exception(reason, fs::path(path1), fs::path(path2));
  56         }
  57     }
  58 protected:
  59     std::error_code ec() const {
  60         return std::error_code(error, std::system_category());
  61     }
  62 };
  63
  64 // Wrapper for a system call result containing the return value,
  65 // an output parameter that was returned from the syscall, and errno.
  66 template <typename Extra>
  67 struct syscall_result_extra : public syscall_result<int> {
  68     Extra extra;
  69     syscall_result_extra(int result, int error, Extra e) : syscall_result<int>{result, error}, extra{std::move(e)} {
  70     }
  71 };
  72
  73 template <typename T>
  74 syscall_result<T>
  75 wrap_syscall(T result) {
  76     return syscall_result<T>{std::move(result), errno};
  77 }
  78
  79 template <typename Extra>
  80 syscall_result_extra<Extra>
  81 wrap_syscall(int result, const Extra& extra) {
  82     return syscall_result_extra<Extra>{result, errno, extra};
  83 }
  84
  85 }