ret = read(socketFd, &frame, sizeof(struct can_frame)); if(ret < 0) { qDebug() << "CAN accept failure!"; } else if (ret < sizeof(frame)) { qDebug() << "CAN receive data is not long enough!"; } else if (frame.can_id & CAN_ERR_FLAG) { qDebug() << "CAN receive the frame error!"; } else { qtime->restart();

这段代码是用来接收 CAN 总线上的数据帧的，其中 socketFd 是指向 CAN 总线的套接字文件描述符，frame 是一个结构体，用来存储接收到的数据帧。代码中首先调用 read 函数来读取数据，如果返回值小于 0，说明读取失败；如果返回值小于 frame 的大小，说明接收到的数据不完整；如果数据帧的标识符中包含错误标志位，说明接收到的是错误帧；否则就重启一个计时器，并且可以对接收到的数据进行处理。其中 qtime 是一个 QTimer 对象，用来计时。

相关问题

int CFactoryTool::CheckUnattachedPhyStatus() { int sockfd = 0; struct mii_ioctl_data* mii = NULL; struct ifreq ifr = { 0 }; int ret = 0; unsigned int phyid = 0; memset(&ifr, 0, sizeof(ifr)); strncpy(ifr.ifr_name, "eth0", IFNAMSIZ - 1); sockfd = socket(PF_LOCAL, SOCK_DGRAM, 0); if (sockfd < 0) { return PERIPHERAL_BRK; } // get phy address in smi bus ret = ioctl(sockfd, SIOCGMIIPHY, &ifr); if (ret < 0) { close(sockfd); return PERIPHERAL_BRK; } mii = (struct mii_ioctl_data*)&ifr.ifr_data; mii->reg_num = 2; ret = ioctl(sockfd, SIOCGMIIREG, &ifr); if (ret < 0) { close(sockfd); return PERIPHERAL_BRK; } phyid = 0xffff & mii->val_out; mii->reg_num = 3; ret = ioctl(sockfd, SIOCGMIIREG, &ifr); if (ret < 0) { close(sockfd); return PERIPHERAL_BRK; } phyid |= (0xffff & mii->val_out) << 16; close(sockfd); if (phyid == 0) { return PERIPHERAL_BRK; } else { return PERIPHERAL_OK; } }

这是一个C++语言的函数，用于检查网络接口eth0上是否存在未连接的物理设备。函数返回值为整数类型，表示检查结果，PERIPHERAL_OK表示检查通过，PERIPHERAL_BRK表示检查失败。

该函数使用了Linux系统的网络接口控制命令ioctl()，其中SIOCGMIIPHY和SIOCGMIIREG分别用于获取PHY地址和PHY寄存器的值。函数中还使用了结构体ifreq和mii_ioctl_data，用于存储和传递网络接口和PHY相关的信息。

函数实现的逻辑为，先打开一个本地socket，然后使用ioctl()函数获取网络接口eth0上的PHY地址，再通过PHY地址获取PHY的寄存器值，最后根据寄存器值判断是否存在未连接的PHY设备。

修改client.c： #include<stdio.h> #include<stdlib.h> #include<string.h> #include<errno.h> #include<sys/types.h> #include<sys/socket.h> #include<netinet/in.h> int main() { int ret = 0; int socket_fd; char buffer[100]="你好，我是xxx!"; struct sockaddr_in server_add; socket_fd = socket(AF_INET, SOCK_STREAM, 0); if(-1 == socket_fd) { printf("socket fail ! \r\n"); return -1; } bzero(&server_add,sizeof(struct sockaddr_in)); server_add.sin_family=AF_INET; server_add.sin_addr.s_addr= inet_addr("192.168.1.2"); server_add.sin_port=htons(8888); if(-1 == connect(socket_fd,(struct sockaddr *)(&server_add), sizeof(struct sockaddr))) { printf("connect fail !\r\n"); return -1; } ret = write(socket_fd, buffer, strlen(buffer)); if(-1 == ret ) { printf("write fail!\r\n"); return -1; } close(socket_fd); return 0; }server.c： #include<stdio.h> #include<stdlib.h> #include<string.h> #include<errno.h> #include<sys/types.h> #include<sys/socket.h> #include<netinet/in.h> int main() { int ret = 0; int socket_fd, new_socket_fd; struct sockaddr_in server_add,client_add; int add_len; char recv_buff[100]={0}; char send_buff[100]="朕xxx知道了!"; socket_fd = socket(AF_INET, SOCK_STREAM, 0); if(-1 == socket_fd) { printf("socket fail ! \r\n"); return -1; } bzero(&server_add,sizeof(struct sockaddr_in)); server_add.sin_family=AF_INET; server_add.sin_addr.s_addr=htonl(INADDR_ANY); server_add.sin_port=htons(8888); if(-1 == bind(socket_fd,(struct sockaddr *)(&server_add), sizeof(struct sockaddr))) { printf("bind fail !\r\n"); return -1; } if(-1 == listen(socket_fd,5)) { printf("listen fail !\r\n"); return -1; } while(1) { new_socket_fd = accept(socket_fd, (struct sockaddr *)(&client_add), &add_len); if(-1 == new_socket_fd) { printf("accept fail !\r\n"); return -1; } ret = read(new_socket_fd, recv_buff,100); if(-1 == ret) { printf("read data fail !\r\n"); return -1; } printf("Now we get:%s from client!\n", recv_buff); ret = write(socket_fd, send_buff, strlen(send_buff)); if(-1 == ret ) { printf("write fail!\r\n"); return -1; } close(new_socket_fd); } close(socket_fd); return 0; }修改服务器和客户端，使朕知道了正常输出

修改后的client.c：

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<errno.h>
#include<sys/types.h>
#include<sys/socket.h>
#include<netinet/in.h>

int main() {
    int ret = 0;
    int socket_fd;
    char buffer[100]="你好，我是xxx!";
    struct sockaddr_in server_add;

    socket_fd = socket(AF_INET, SOCK_STREAM, 0);
    if(-1 == socket_fd)
    {
        printf("socket fail ! \r\n");
        return -1;
    }

    bzero(&server_add,sizeof(struct sockaddr_in));
    server_add.sin_family=AF_INET;
    server_add.sin_addr.s_addr= inet_addr("192.168.1.2");
    server_add.sin_port=htons(8888);

    if(-1 == connect(socket_fd,(struct sockaddr *)(&server_add), sizeof(struct sockaddr)))
    {
        printf("connect fail !\r\n");
        return -1;
    }

    ret = write(socket_fd, buffer, strlen(buffer));
    if(-1 == ret )
    {   
        printf("write fail!\r\n");
        return -1;
    }

    ret = read(socket_fd, buffer,100);
    if(-1 == ret) {
        printf("read data fail !\r\n");
        return -1;
    }

    printf("Now we get:%s from server!\n", buffer);

    close(socket_fd);
    return 0;
}

修改后的server.c：

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<errno.h>
#include<sys/types.h>
#include<sys/socket.h>
#include<netinet/in.h>

int main() {
    int ret = 0;
    int socket_fd, new_socket_fd;
    struct sockaddr_in server_add,client_add;
    int add_len;
    char recv_buff[100]={0};
    char send_buff[100]="朕xxx知道了!";

    socket_fd = socket(AF_INET, SOCK_STREAM, 0);
    if(-1 == socket_fd) {
        printf("socket fail ! \r\n");
        return -1;
    }

    bzero(&server_add,sizeof(struct sockaddr_in));
    server_add.sin_family=AF_INET;
    server_add.sin_addr.s_addr=htonl(INADDR_ANY);
    server_add.sin_port=htons(8888);

    if(-1 == bind(socket_fd,(struct sockaddr *)(&server_add), sizeof(struct sockaddr))) {
        printf("bind fail !\r\n");
        return -1;
    }

    if(-1 == listen(socket_fd,5)) {
        printf("listen fail !\r\n");
        return -1;
    }

    while(1) {
        new_socket_fd = accept(socket_fd, (struct sockaddr *)(&client_add), &add_len);
        if(-1 == new_socket_fd) {
            printf("accept fail !\r\n");
            return -1;
        }

        ret = read(new_socket_fd, recv_buff,100);
        if(-1 == ret) {
            printf("read data fail !\r\n");
            return -1;
        }

        printf("Now we get:%s from client!\n", recv_buff);

        ret = write(new_socket_fd, send_buff, strlen(send_buff));
        if(-1 == ret ) {
            printf("write fail!\r\n");
            return -1;
        }

        close(new_socket_fd);
    }

    close(socket_fd);
    return 0;
}

在客户端发送消息后，服务器会返回“朕xxx知道了!”，客户端会输出“Now we get:朕xxx知道了! from server!”。