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/*
* Copyright (C) 2015 by Multi-Tech Systems
*
* This file is part of libmts-io.
*
* libmts-io 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-io 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-io. If not, see <http://www.gnu.org/licenses/>.
*
*/
/*!
\file MTS_IO_LockFile.cpp
\brief A brief description
\date Oct 8, 2014
\author sgodinez
A more elaborate description
*/
#include <mts/MTS_IO_LockFile.h>
#include <mts/MTS_Timer.h>
#include <mts/MTS_Logger.h>
#include <mts/MTS_System.h>
#include <mts/MTS_Text.h>
#include <sys/file.h>
#include <sys/stat.h>
#include <errno.h>
#include <string.h>
#include <unistd.h>
using namespace MTS::IO;
LockFile::LockFile(const std::string& sFile)
: m_sFile(sFile)
, m_iLockFd(-1)
{
}
LockFile::~LockFile() {
unlock();
}
bool LockFile::lock(uint32_t attemptMillis) {
if(isLocked()) {
return true;
}
MTS::Timer timer;
timer.start();
while(timer.getMillis() < attemptMillis) {
m_iLockFd =::open(m_sFile.c_str(), O_CREAT | O_WRONLY | O_TRUNC | O_EXCL, 0644);
if (m_iLockFd < 0) {
// device already locked -> bail out
printWarning("LockFile| Failed to Lock [%s] [%d][%s]", m_sFile.c_str(), errno, strerror(errno));
//Check if lock file's process still exists
std::string sResult;
if(MTS::System::readFile(m_sFile, sResult) == 0 && sResult.size() > 0) {
struct stat sts;
std::string sProc = "/proc/" + MTS::Text::trim(sResult);
if (stat(sProc.c_str(), &sts) == -1 && errno == ENOENT) {
printWarning("LockFile| Current Lock's Process [%s] does not exist. Removing lock.", sResult.c_str());
// process doesn't exist -> remove file
::unlink(m_sFile.c_str());
}
}
} else {
//TODO: Investigate using flock in addition to minicom-style lock : flock(m_iLockFd, LOCK_EX | LOCK_NB);
// %4d to make concurrent mgetty (if any) happy.
// Mgetty treats 4-bytes lock files as binary,
// not text, PID. Making 5+ char file. Brrr...
char buf[256] = {0};
size_t written = 0;
sprintf(buf, "%4d\n", getpid());
size_t wsize = strlen(buf);
written = write(m_iLockFd, buf, wsize);
if (wsize != written) {
printError("LockFile| Error writing to lock file [%s] [%d][%s]", m_sFile.c_str(), errno, strerror(errno));
close(m_iLockFd);
return false;
}
else {
close(m_iLockFd);
return true;
}
}
uint32_t randomSleepTime = ((rand() % 10) + 1) * 100000; //Sleep from 100ms to 1 Second
::usleep(randomSleepTime);
}
return false;
}
void LockFile::unlock() {
if(isLocked()) {
::unlink(m_sFile.c_str());
//TODO: flock cleanup : flock(m_iLockFd, LOCK_UN);
m_iLockFd = -1;
}
}
bool LockFile::isLocked() {
return m_iLockFd >= 0;
}
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