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/*
* Copyright (C) 2015 by Multi-Tech Systems
*
* This file is part of libmts.
*
* libmts is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation, either version 2 of the License, or
* (at your option) any later version.
*
* libmts 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 Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with libmts. If not, see <http://www.gnu.org/licenses/>.
*
*/
/*! \file MTS_System.h
\brief System Utilities
\date 15JUN11
\author Sean Godinez
System utilities for time, endian, etc.
*/
#ifndef MTS_SYSTEM_H
#define MTS_SYSTEM_H
#include <mts/MTS_NonConstructable.h>
#include <mts/MTS_Stdint.h>
#include <string>
#include <vector>
namespace MTS {
class System: private NonConstructable {
public:
//! Type of the pipe to be opened in executeBackground
enum class PipeType {
READ, WRITE
};
//! Utility structure with information about the child process
struct ChildHandle {
pid_t pid;
FILE* stream;
};
//UTC (Coordinated Universal Time) : This is the standard international time or the Greenwich Mean Time.
//EPOCH : number of seconds elapsed since 00:00:00 on January 1, 1970, Coordinated Universal Time.
static uint64_t timeMicros();
static uint64_t precisionTimeMicros();
//MONOTONIC : number of seconds elapsed since some unspecified starting point. When time is changed by user, timer are unaffected.
static uint64_t monoTimeMicros();
static bool isBigEndian();
static void swapBytes(uint8_t* const pBuffer, const uint32_t iSize);
static int32_t cmd(const std::string& cmd, std::string& result);
static int32_t readFile(const std::string& path, std::string& result);
//! Execute application with specified arguments.
/*!
* A safer alternative to System::cmd that allows to execute applications with controlled
* list of arguments bypasing the system shell.
*
* \param cmd name of the application to be executed
* \param argv vector of arguments (excluding argument zero)
* \param result stdout output from the application is stored here
* \return result code as for std::system and UNIX pclose
*/
static int32_t execute(const std::string& cmd, const std::vector<std::string>& argv, std::string& result);
//! Spawn a process and open pipe with the specified type (READ or WRITE)
/*!
* A safer alternative to POSIX popen that allows to execute applications with controlled
* list of arguments bypasing the system shell. If succeded, information about the spawned
* process is written to the \p child structure.
*
* \param cmd name of the application to be executed
* \param argv vector of arguments (excluding argument zero)
* \param type open pipe for read from child or write to child
* \param child on success is populated with child process information, on failure is not defined
* \return true on success, false on failure
*/
static bool executeBackground(const std::string& cmd, const std::vector<std::string>& argv, PipeType type, ChildHandle& child);
//! Close the pipe and wait for a child to finish execution
/*!
* \param child structure with child process information as populated by executeBackground
* \return result code as for std::system and UNIX pclose
*/
static int closeBackground(ChildHandle& child);
private:
//! Spawn a process and open pipe with the specified type (READ or WRITE)
static bool executeBackground(const std::string& cmd, char* const argv[], PipeType type, ChildHandle& child);
//! Utility method. Cast argument to a C pointer required by some C-style functions.
static inline char* castArgument(const std::string& arg);
//! Utility method. Convert argument vector to a format required by execve and posix_spawn.
static std::vector<char*> castArgVector(const std::string& cmd, const std::vector<std::string>& argv);
//! Lightweight C++ wrapper with auto-close for file descriptors
class FdWrapper {
public:
static const int FD_NOT_READY = -1;
explicit FdWrapper(int fd = FD_NOT_READY);
~FdWrapper();
inline int get() const;
int release();
void reset(int fd = FD_NOT_READY);
private:
int m_fd;
};
//! Utility structure, used by popen wrapper
struct Pipe {
FdWrapper parent;
FdWrapper child;
};
//! Initialize UNIX pipe
static int initPipe(Pipe& pipe, PipeType type);
};
}
#endif
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