process-cpp 3.0.0
A simple convenience library for handling processes in C++11.
this_process.cpp
Go to the documentation of this file.
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
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
35extern char** environ;
36#endif
37
38namespace core
39{
40namespace posix
41{
42namespace this_process
43{
44namespace env
45{
46namespace
47{
48std::mutex& env_guard()
49{
50 static std::mutex m;
51 return m;
52}
53}
54
55void 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
68std::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
84std::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
93void 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
103bool 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
119void 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
131bool 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
151{
152 static const Process self{getpid()};
153 return self;
154}
155
157{
158 return Process(getppid());
159}
160
161std::istream& cin() noexcept(true)
162{
163 return std::cin;
164}
165
166std::ostream& cout() noexcept(true)
167{
168 return std::cout;
169}
170
171std::ostream& cerr() noexcept(true)
172{
173 return std::cerr;
174}
175}
176}
177}
The Process class models a process and possible operations on it.
Definition process.h:45
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.
CORE_POSIX_DLL_PUBLIC std::string get_or_throw(const std::string &key)
get queries the value of an environment variable.
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.
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.
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.
CORE_POSIX_DLL_PUBLIC void unset_or_throw(const std::string &key)
unset_or_throw removes the variable with name key from the environment.
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.
CORE_POSIX_DLL_PUBLIC std::ostream & cout() noexcept(true)
Access this process's stdout.
CORE_POSIX_DLL_PUBLIC Process parent() noexcept(true)
Query the parent of the process.
CORE_POSIX_DLL_PUBLIC std::ostream & cerr() noexcept(true)
Access this process's stderr.
CORE_POSIX_DLL_PUBLIC Process instance() noexcept(true)
Returns a Process instance corresponding to this process.
CORE_POSIX_DLL_PUBLIC std::istream & cin() noexcept(true)
Access this process's stdin.
Signal
The Signal enum collects the most common POSIX signals.
Definition signal.h:39
char ** environ