1 files changed, 109 insertions, 0 deletions
diff --git a/src/MTS_IO_LockFile.cpp b/src/MTS_IO_LockFile.cpp
new file mode 100644
index 0000000..c013699
--- /dev/null
+++ b/src/MTS_IO_LockFile.cpp
@@ -0,0 +1,109 @@
+/*
+ * 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};
+            sprintf(buf, "%4d\n", getpid());
+            write(m_iLockFd, buf, strlen(buf));
+            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;
+}
+