feat(CSerialPortUnixBase): #27 unix support exclusive mode by lock file

Signed-off-by: itas109 <itas109@qq.com>

Author: itas109

examples/CommNoGui/Makefile

@@ -12,6 +12,7 @@ SRC = ${DEMO_DIR}/CSerialPortDemoNoGui.cpp \
       ${SRC_DIR}/SerialPortInfoUnixBase.cpp \
       ${SRC_DIR}/SerialPort.cpp \
       ${SRC_DIR}/SerialPortBase.cpp \
+      ${SRC_DIR}/SerialPortAsyncBase.cpp \
       ${SRC_DIR}/SerialPortUnixBase.cpp
 
 OBJ = ${SRC}

examples/CommNoGui/compile.sh

@@ -1,3 +1,3 @@
 #! /bin/bash
 
-g++ -std=c++11 CSerialPortDemoNoGui.cpp ../../src/SerialPortInfo.cpp ../../src/SerialPortInfoBase.cpp ../../src/SerialPortInfoUnixBase.cpp ../../src/SerialPort.cpp ../../src/SerialPortBase.cpp ../../src/SerialPortUnixBase.cpp -lpthread -I../../include -o CSerialPortDemoNoGui
+g++ -std=c++11 CSerialPortDemoNoGui.cpp ../../src/SerialPortInfo.cpp ../../src/SerialPortInfoBase.cpp ../../src/SerialPortInfoUnixBase.cpp ../../src/SerialPort.cpp ../../src/SerialPortBase.cpp ../../src/SerialPortUnixAsyncBase.cpp ../../src/SerialPortUnixBase.cpp -lpthread -I../../include -o CSerialPortDemoNoGui

examples/CommQT/mainwindow.cpp

@@ -105,7 +105,7 @@ void MainWindow::on_pushButtonOpen_clicked()
                               ui->comboBoxBaudrate->currentText().toInt(),
                               itas109::Parity(ui->comboBoxParity->currentIndex()),
                               itas109::DataBits(ui->comboBoxDataBit->currentText().toInt()),
-                              itas109::StopBits(ui->comboBoxStopBit->currentIndex()));
+                              itas109::StopBits(ui->comboBoxStopBit->currentText().toInt()));
 
             m_SerialPort.setReadIntervalTimeout(ui->lineEditReadIntervalTimeoutMS->text().toInt());
 

examples/CommQT/mainwindow.ui

@@ -392,11 +392,6 @@
                     <string>1</string>
                    </property>
                   </item>
-                  <item>
-                   <property name="text">
-                    <string>1.5</string>
-                   </property>
-                  </item>
                   <item>
                    <property name="text">
                     <string>2</string>

include/CSerialPort/SerialPortUnixBase.h

@@ -23,6 +23,11 @@
 
 #include "SerialPortAsyncBase.h"
 
+namespace itas109
+{
+class ILockFile;
+}
+
 // Serial Programming Guide for POSIX Operating Systems
 // https://www.msweet.org/serial/serial.html
 
@@ -195,6 +200,7 @@ class CSerialPortUnixBase : public CSerialPortAsyncBase
     int waitCommEventNative() override final;
 
 private:
-    int pipefd[2]; ///< pipe file descriptor for wake up read thread 用于唤醒读取线程的管道文件描述符
+    int m_pipefd[2];                                          ///< pipe file descriptor for wake up read thread 用于唤醒读取线程的管道文件描述符
+    std::unique_ptr<itas109::ILockFile> m_serialPortFileLock; ///< lock file for serial port 串口锁文件
 };
 #endif //__CSERIALPORT_UNIX_BASE_H__

include/CSerialPort/ilockfile.hpp

@@ -0,0 +1,178 @@
+/**
+ * @file ilockfile.hpp
+ * @author itas109 (itas109@qq.com) \n\n
+ * Blog : https://blog.csdn.net/itas109 \n
+ * Github : https://github.com/itas109 \n
+ * Gitee : https://gitee.com/itas109 \n
+ * QQ Group : 129518033
+ * @brief lightweight cross-platform lock file library 轻量级跨平台锁文件类
+ */
+#ifndef __I_LOCKFILE_HPP__
+#define __I_LOCKFILE_HPP__
+
+#pragma once
+
+#include <stdio.h>
+#include <string.h>
+#include <errno.h>
+#include <string> // std::atoi
+
+#if defined(_WIN32)
+#define LOCKFILE_UNSUPPORTED
+#else
+#include <unistd.h>
+#include <fcntl.h>
+#include <sys/stat.h>
+#include <signal.h>
+#endif
+
+namespace itas109
+{
+class ILockFile
+{
+public:
+    ILockFile()
+        : m_fd(-1)
+    {
+        m_path[0] = '\0';
+    }
+
+    ~ILockFile()
+    {
+        unlock();
+    }
+
+    bool lock(const char *deviceName)
+    {
+#ifdef LOCKFILE_UNSUPPORTED
+        (void)deviceName;
+        return false;
+#else
+        if (!buildLockPath(deviceName))
+        {
+            return false;
+        }
+
+        if (tryCreate())
+        {
+            return true;
+        }
+
+        if (errno == EEXIST)
+        {
+            if (checkStaleAndRecover())
+            {
+                return true;
+            }
+            return false;
+        }
+
+        if (errno == EACCES || errno == EPERM)
+        {
+            return false;
+        }
+
+        return false;
+#endif
+    }
+
+    void unlock()
+    {
+#ifndef LOCKFILE_UNSUPPORTED
+        if (m_fd >= 0)
+        {
+            close(m_fd);
+            unlink(m_path);
+            m_fd = -1;
+        }
+#endif
+    }
+
+    const char *path() const
+    {
+        return m_path;
+    }
+
+private:
+#ifndef LOCKFILE_UNSUPPORTED
+    bool buildLockPath(const char *deviceName)
+    {
+        const char *base = strrchr(deviceName, '/');
+        base = base ? base + 1 : deviceName;
+
+        const char *dirs[] = {
+#if defined(__APPLE__)
+            "/var/spool/uucp",
+#elif defined(__linux__)
+            "/run/lock",
+            "/var/lock",
+            "/var/spool/uucp",
+#else
+            "/var/spool/lock",
+            "/var/spool/uucp",
+#endif
+            ".", // current directory
+        };
+
+        for (size_t i = 0; i < sizeof(dirs) / sizeof(dirs[0]); ++i)
+        {
+            if (access(dirs[i], W_OK) == 0)
+            {
+                snprintf(m_path, sizeof(m_path), "%s/LCK..%s", dirs[i], base);
+                return true;
+            }
+        }
+        return false;
+    }
+
+    bool tryCreate()
+    {
+        m_fd = open(m_path, O_CREAT | O_EXCL | O_WRONLY, 0644);
+        if (m_fd < 0)
+        {
+            return false;
+        }
+
+        char buf[32];
+        snprintf(buf, sizeof(buf), "%ld\n", (long)getpid());
+        write(m_fd, buf, strlen(buf));
+        return true;
+    }
+
+    bool checkStaleAndRecover()
+    {
+        // get pid from lock file
+        int fd = open(m_path, O_RDONLY);
+        if (fd < 0)
+        {
+            return false;
+        }
+
+        char buf[32] = {0};
+        read(fd, buf, sizeof(buf) - 1);
+        close(fd);
+
+        pid_t pid = (pid_t)std::atoi(buf);
+        if (pid <= 0)
+        {
+            return false;
+        }
+
+        // check if process is running
+        if (kill(pid, 0) == -1 && errno == ESRCH)
+        {
+            // stale lock
+            unlink(m_path);
+            return tryCreate();
+        }
+        return false;
+    }
+#endif
+
+private:
+    char m_path[256];
+    int m_fd;
+};
+
+} // namespace itas109
+#endif // __I_LOCKFILE_HPP__