process-cpp: /build/process-cpp/src/process-cpp-3.0.1/src/core/posix/this_process.cpp Source File

process-cpp 3.0.0 A simple convenience library for handling processes in C++11.

this_process.cpp
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1 /*
2 * Copyright © 2013 Canonical Ltd.
3 *
4 * This program is free software: you can redistribute it and/or modify it
5 * under the terms of the GNU Lesser General Public License version 3,
6 * as published by the Free Software Foundation.
7 *
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11 * GNU Lesser General Public License for more details.
12 *
13 * You should have received a copy of the GNU Lesser General Public License
14 * along with this program. If not, see <http://www.gnu.org/licenses/>.
15 *
16 * Authored by: Thomas Voß <thomas.voss@canonical.com>
17 */
18
19 #include <core/posix/this_process.h>
20 #include <core/posix/process.h>
21
22 #include <boost/algorithm/string.hpp>
23
24 #include <iostream>
25 #include <mutex>
26 #include <sstream>
27 #include <vector>
28
29 #include <cerrno>
30 #include <cstdlib>
31
32 #if defined(_GNU_SOURCE)
33 #include <unistd.h>
34 #else
35 extern char** environ;
36 #endif
37
38 namespace core
39 {
40 namespace posix
41 {
42 namespace this_process
43 {
44 namespace env
45 {
46 namespace
47 {
48 std::mutex& env_guard()
49 {
50 static std::mutex m;
51 return m;
52 }
53 }
54
55 void for_each(const std::function<void(const std::string&, const std::string&)>& functor) noexcept(true)
56 {
57 std::lock_guard<std::mutex> lg(env_guard());
58 auto it = ::environ;
59 while (it != nullptr && *it != nullptr)
60 {
61 std::string line(*it);
62 functor(line.substr(0,line.find_first_of('=')),
63 line.substr(line.find_first_of('=')+1));
64 ++it;
65 }
66 }
67
68 std::string get_or_throw(const std::string& key)
69 {
70 std::lock_guard<std::mutex> lg(env_guard());
71
72 auto result = ::getenv(key.c_str());
73
74 if (result == nullptr)
75 {
76 std::stringstream ss;
77 ss << "Variable with name " << key << " is not defined in the environment";
78 throw std::runtime_error(ss.str());
79 }
80
81 return std::string{result};
82 }
83
84 std::string get(const std::string& key,
85 const std::string& default_value) noexcept(true)
86 {
87 std::lock_guard<std::mutex> lg(env_guard());
88
89 auto result = ::getenv(key.c_str());
90 return std::string{result ? result : default_value};
91 }
92
93 void unset_or_throw(const std::string& key)
94 {
95 std::lock_guard<std::mutex> lg(env_guard());
96
97 auto rc = ::unsetenv(key.c_str());
98
99 if (rc == -1)
100 throw std::system_error(errno, std::system_category());
101 }
102
103 bool unset(const std::string& key,
104 std::error_code& se) noexcept(true)
105 {
106 std::lock_guard<std::mutex> lg(env_guard());
107
108 auto rc = ::unsetenv(key.c_str());
109
110 if (rc == -1)
111 {
112 se = std::error_code(errno, std::system_category());
113 return false;
114 }
115
116 return true;
117 }
118
119 void set_or_throw(const std::string& key,
120 const std::string& value)
121 {
122 std::lock_guard<std::mutex> lg(env_guard());
123
124 static const int overwrite = 0;
125 auto rc = ::setenv(key.c_str(), value.c_str(), overwrite);
126
127 if (rc == -1)
128 throw std::system_error(errno, std::system_category());
129 }
130
131 bool set(const std::string &key,
132 const std::string &value,
133 std::error_code& se) noexcept(true)
134 {
135 std::lock_guard<std::mutex> lg(env_guard());
136
137 static const int overwrite = 0;
138 auto rc = ::setenv(key.c_str(), value.c_str(), overwrite);
139
140 if (rc == -1)
141 {
142 se = std::error_code(errno, std::system_category());
143 return false;
144 }
145
146 return true;
147 }
148 }
149
150 Process instance() noexcept(true)
151 {
152 static const Process self{getpid()};
153 return self;
154 }
155
156 Process parent() noexcept(true)
157 {
158 return Process(getppid());
159 }
160
161 std::istream& cin() noexcept(true)
162 {
163 return std::cin;
164 }
165
166 std::ostream& cout() noexcept(true)
167 {
168 return std::cout;
169 }
170
171 std::ostream& cerr() noexcept(true)
172 {
173 return std::cerr;
174 }
175 }
176 }
177 }
core::posix::this_process::env::get
CORE_POSIX_DLL_PUBLIC std::string get(const std::string &key, const std::string &default_value=std::string()) noexcept(true)
get queries the value of an environment variable.
Definition: this_process.cpp:84
core::posix::this_process::instance
CORE_POSIX_DLL_PUBLIC Process instance() noexcept(true)
Returns a Process instance corresponding to this process.
Definition: this_process.cpp:150
core::posix::this_process::env::set
CORE_POSIX_DLL_PUBLIC bool set(const std::string &key, const std::string &value, std::error_code &se) noexcept(true)
set will adjust the contents of the variable identified by key to the provided value.
Definition: this_process.cpp:131
core::posix::this_process::env::set_or_throw
CORE_POSIX_DLL_PUBLIC void set_or_throw(const std::string &key, const std::string &value)
set_or_throw will adjust the contents of the variable identified by key to the provided value.
Definition: this_process.cpp:119
this_process.h
core::posix::this_process::env::get_or_throw
CORE_POSIX_DLL_PUBLIC std::string get_or_throw(const std::string &key)
get queries the value of an environment variable.
Definition: this_process.cpp:68
core::posix::this_process::cerr
CORE_POSIX_DLL_PUBLIC std::ostream & cerr() noexcept(true)
Access this process's stderr.
Definition: this_process.cpp:171
process.h
core
Definition: child_process.h:32
core::posix::this_process::cin
CORE_POSIX_DLL_PUBLIC std::istream & cin() noexcept(true)
Access this process's stdin.
Definition: this_process.cpp:161
core::posix::this_process::cout
CORE_POSIX_DLL_PUBLIC std::ostream & cout() noexcept(true)
Access this process's stdout.
Definition: this_process.cpp:166
core::posix::this_process::env::for_each
CORE_POSIX_DLL_PUBLIC void for_each(const std::function< void(const std::string &, const std::string &)> &functor) noexcept(true)
for_each invokes a functor for every key-value pair in the environment.
Definition: this_process.cpp:55
core::posix::this_process::env::unset
CORE_POSIX_DLL_PUBLIC bool unset(const std::string &key, std::error_code &se) noexcept(true)
unset removes the variable with name key from the environment.
Definition: this_process.cpp:103
core::posix::this_process::parent
CORE_POSIX_DLL_PUBLIC Process parent() noexcept(true)
Query the parent of the process.
Definition: this_process.cpp:156
core::posix::this_process::env::unset_or_throw
CORE_POSIX_DLL_PUBLIC void unset_or_throw(const std::string &key)
unset_or_throw removes the variable with name key from the environment.
Definition: this_process.cpp:93
environ
char ** environ
core::posix::Process
The Process class models a process and possible operations on it.
Definition: process.h:45