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// OpenVPN -- An application to securely tunnel IP networks
// over a single port, with support for SSL/TLS-based
// session authentication and key exchange,
// packet encryption, packet authentication, and
// packet compression.
//
// Copyright (C) 2012-2022 OpenVPN Inc.
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License Version 3
// as published by the Free Software Foundation.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program in the COPYING file.
// If not, see <http://www.gnu.org/licenses/>.
// General-purpose classes for instantiating a posix process with arguments.
#pragma once
#ifndef _WIN32
#include <stdlib.h> // exit
#include <unistd.h> // fork, execve
#include <sys/types.h> // waitpid
#include <sys/wait.h> // waitpid
#include <string>
#include <memory>
#include <utility>
#include <openvpn/common/action.hpp>
#include <openvpn/common/redir.hpp>
#include <openvpn/common/signal.hpp>
#include <openvpn/common/argv.hpp>
#include <openvpn/common/environ.hpp>
namespace openvpn {
// low-level fork/exec (async)
inline pid_t system_cmd_async(const std::string &cmd,
const Argv &argv,
const Environ *env,
RedirectBase *redir,
const sigset_t *sigmask)
{
ArgvWrapper argv_wrap(argv);
std::unique_ptr<ArgvWrapper> env_wrap;
if (env)
env_wrap.reset(new ArgvWrapper(*env));
auto fn = cmd.c_str();
auto av = argv_wrap.c_argv();
auto ev = env_wrap ? env_wrap->c_argv() : ::environ;
#if defined(__APPLE__)
/* macOS vfork is deprecated and behaves identical to fork() */
const pid_t pid = ::fork();
#else
const pid_t pid = (redir || sigmask) ? ::fork() : ::vfork();
#endif
if (pid == pid_t(0)) /* child side */
{
// Only Async-signal-safe functions as specified by
// SIGNAL(7) can be called between here and _exit().
if (sigmask)
::pthread_sigmask(SIG_SETMASK, sigmask, 0);
if (redir)
redir->redirect();
::execve(fn, av, ev);
::_exit(127);
}
else if (pid < pid_t(0)) /* fork failed */
return -1;
else /* parent side */
{
if (redir)
redir->close();
return pid;
}
}
// completion for system_cmd_async()
inline int system_cmd_post(const pid_t pid)
{
int status = -1;
if (::waitpid(pid, &status, 0) == pid)
{
if (WIFEXITED(status))
return WEXITSTATUS(status);
}
return -1;
}
// synchronous version of system_cmd_async
inline int system_cmd(const std::string &cmd,
const Argv &argv,
RedirectBase *redir,
const Environ *env,
const sigset_t *sigmask)
{
const pid_t pid = system_cmd_async(cmd, argv, env, redir, sigmask);
if (pid < pid_t(0))
return -1;
return system_cmd_post(pid);
}
// simple command execution
inline int system_cmd(const std::string &cmd, const Argv &argv)
{
return system_cmd(cmd, argv, nullptr, nullptr, nullptr);
}
// simple command execution
inline int system_cmd(const Argv &argv)
{
int ret = -1;
if (argv.size())
ret = system_cmd(argv[0], argv);
return ret;
}
// command execution with std::strings as
// input/output/error (uses pipes under the
// hood)
inline int system_cmd(const std::string &cmd,
const Argv &argv,
const Environ *env,
RedirectPipe::InOut &inout,
unsigned int redirect_pipe_flags,
const sigset_t *sigmask)
{
SignalBlockerPipe sbpipe;
RedirectPipe remote;
if (!inout.in.empty())
redirect_pipe_flags |= RedirectPipe::ENABLE_IN;
RedirectPipe local(remote, redirect_pipe_flags);
const pid_t pid = system_cmd_async(cmd, argv, env, &remote, sigmask);
if (pid < pid_t(0))
return -1;
local.transact(inout);
return system_cmd_post(pid);
}
struct Command : public Action
{
typedef RCPtr<Command> Ptr;
Command()
{
}
Command(Argv argv_arg)
: argv(std::move(argv_arg))
{
}
Command *copy() const
{
Command *ret = new Command;
ret->argv = argv;
return ret;
}
virtual void execute(std::ostream &os) override
{
if (!argv.empty())
{
os << to_string() << std::endl;
#ifdef OPENVPN_PROCESS_AVOID_PIPES
const int status = system_cmd(argv[0], argv);
if (status < 0)
os << "Error: command failed to execute" << std::endl;
#else
RedirectPipe::InOut inout;
const int status = system_cmd(argv[0], argv, nullptr, inout, RedirectPipe::COMBINE_OUT_ERR, nullptr);
if (status < 0)
os << "Error: command failed to execute" << std::endl;
os << inout.out;
#endif
}
else
os << "Error: command called with empty argv" << std::endl;
}
virtual std::string to_string() const override
{
return argv.to_string();
}
Argv argv;
};
} // namespace openvpn
#endif
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