Question

我正在尝试实现一个简单的syslog应用程序。它应该创建一个/ dev / log套接字，同时它将在无限循环中接收logger终端命令提供的日志消息。我的代码的当前状态如下：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <unistd.h>

#define SOCKET_NAME "/dev/log"
#define BUFFER_SIZE 50

int main()
{
   struct sockaddr_un name;
   int ret;
   int connection_socket;
   int data_socket;
   char buffer[BUFFER_SIZE];

   /*
    * In case the program exited inadvertently on the last run,
    * remove the socket.
    */
   unlink(SOCKET_NAME);

   /* Create local socket. */
   connection_socket = socket(AF_UNIX, SOCK_DGRAM, 0);
   if (connection_socket == -1) {
       perror("socket");
       exit(EXIT_FAILURE);
   }

   /*
    * For portability clear the whole structure, since some
    * implementations have additional (nonstandard) fields in
    * the structure.
    */
   memset(&name, 0, sizeof(struct sockaddr_un));

   /* Bind socket to socket name. */
   name.sun_family = AF_UNIX;
   strncpy(name.sun_path, SOCKET_NAME, sizeof(name.sun_path));
   name.sun_path[sizeof(name.sun_path)-1] = '\0';
   ret = bind(connection_socket, (const struct sockaddr *) &name, SUN_LEN(&name));
   if (ret == -1) {
       perror("bind");
       exit(EXIT_FAILURE);
   }

   /*
    * Prepare for accepting connections. The backlog size is set
    * to 20. So while one request is being processed other requests
    * can be waiting.
    */
   ret = listen(connection_socket, 20);
   if (ret == -1) {
       perror("listen");
       exit(EXIT_FAILURE);
   }

   /* This is the main loop for handling connections. */
   for (;;) {

       /* Wait for incoming connection. */
       data_socket = accept(connection_socket, NULL, NULL);
       if (data_socket == -1) {
           perror("accept");
           exit(EXIT_FAILURE);
       }

       for (;;) {

           /* Wait for next data packet. */
           ret = read(data_socket, buffer, BUFFER_SIZE);
           if (ret == -1) {
               perror("read");
               exit(EXIT_FAILURE);
           }

           /* Ensure buffer is 0-terminated. */
           buffer[BUFFER_SIZE - 1] = 0;

           /* Printf buffer*/
           printf("Log message: \n", buffer);


       }

       close(data_socket);
   }

   close(connection_socket);

   /* Unlink the socket. */

   unlink(SOCKET_NAME);

   exit(EXIT_SUCCESS);
}

错误消息如下：绑定：地址已在使用中

我的问题是：

为什么会出现上述错误？
是否有解决方案？如果是，怎么办？

我认为此行为是由原始syslog引起的，因此我用systemctl stop rsyslog停止了syslog。但是，这对结果没有影响。

我还尝试了在Error: Address already in use while binding socket with address but the port number is shown free by `netstat`

中找到的建议

最终程序应如下所示：How to read /dev/log?

打印由logger终端命令发送的日志消息

0 个答案: