netlink_kobject_uevent

b'netlink_kobject_uevent' 是一个用于 Linux 内核中的 netlink 模块的函数。它允许用户从内核空间发送事件，该事件在用户空间通过 udev 规则进行处理。此函数允许内核在系统中检测并通知用户空间发生的设备变化。

相关问题

请将下面的程序改为非阻塞 接收 #include <stdio.h> #include <stdlib.h> #include <string.h> #include <fcntl.h> #include <unistd.h> #include <sys/types.h> #include <sys/stat.h> #include <linux/netlink.h> #include <sys/socket.h> #define UEVENT_BUFFER_SIZE 2048 int main(int argc, char **argv) { int fd = socket(AF_NETLINK, SOCK_DGRAM, NETLINK_KOBJECT_UEVENT); if (fd < 0) { perror("Failed to create socket"); return EXIT_FAILURE; } struct sockaddr_nl addr; memset(&addr, 0, sizeof(addr)); addr.nl_family = AF_NETLINK; addr.nl_groups = NETLINK_KOBJECT_UEVENT; if (bind(fd, (struct sockaddr *)&addr, sizeof(addr)) < 0) { perror("Failed to bind socket"); close(fd); return EXIT_FAILURE; } char buf[UEVENT_BUFFER_SIZE]; while (1) { ssize_t n = recv(fd, buf, sizeof(buf), 0); if (n < 0) { perror("Failed to receive data"); close(fd); return EXIT_FAILURE; } char *p = buf; while (p < buf + n) { printf("%s\n", p); p += strlen(p) + 1; } } close(fd); return EXIT_SUCCESS; }

可以使用非阻塞方式来接收消息，使用fcntl函数设置socket为非阻塞模式。在接收数据之前，使用select函数来检查是否有数据可以读取，如果有则接收数据，否则继续等待。修改后的代码如下：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <linux/netlink.h>
#include <sys/socket.h>
#include <sys/select.h>

#define UEVENT_BUFFER_SIZE 2048

int main(int argc, char **argv)
{
    int fd = socket(AF_NETLINK, SOCK_DGRAM, NETLINK_KOBJECT_UEVENT);
    if (fd < 0) {
        perror("Failed to create socket");
        return EXIT_FAILURE;
    }

    struct sockaddr_nl addr;
    memset(&addr, 0, sizeof(addr));
    addr.nl_family = AF_NETLINK;
    addr.nl_groups = NETLINK_KOBJECT_UEVENT;
    if (bind(fd, (struct sockaddr *)&addr, sizeof(addr)) < 0) {
        perror("Failed to bind socket");
        close(fd);
        return EXIT_FAILURE;
    }

    fcntl(fd, F_SETFL, O_NONBLOCK);

    fd_set rfds;
    char buf[UEVENT_BUFFER_SIZE];
    while (1) {
        FD_ZERO(&rfds);
        FD_SET(fd, &rfds);
        int ret = select(fd + 1, &rfds, NULL, NULL, NULL);
        if (ret == -1) {
            perror("Failed to select socket");
            close(fd);
            return EXIT_FAILURE;
        }
        else if (ret) {
            ssize_t n = recv(fd, buf, sizeof(buf), 0);
            if (n < 0) {
                perror("Failed to receive data");
                close(fd);
                return EXIT_FAILURE;
            }

            char *p = buf;
            while (p < buf + n) {
                printf("%s\n", p);
                p += strlen(p) + 1;
            }
        }
    }

    close(fd);
    return EXIT_SUCCESS;
}

uevent_get_property 使用的代码示例

以下是使用`uevent_get_property`函数获取`uevent`事件属性的示例代码：

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/socket.h>
#include <linux/netlink.h>

#define UEVENT_BUFFER_SIZE 2048

int main()
{
    int sockfd;
    struct sockaddr_nl sa;
    int len;
    char buffer[UEVENT_BUFFER_SIZE];

    sockfd = socket(AF_NETLINK, SOCK_RAW, NETLINK_KOBJECT_UEVENT);
    if (sockfd == -1) {
        perror("socket");
        return EXIT_FAILURE;
    }

    memset(&sa, 0, sizeof(sa));
    sa.nl_family = AF_NETLINK;
    sa.nl_groups = NETLINK_KOBJECT_UEVENT;

    if (bind(sockfd, (struct sockaddr *)&sa, sizeof(sa)) == -1) {
        perror("bind");
        close(sockfd);
        return EXIT_FAILURE;
    }

    while (1) {
        len = recv(sockfd, buffer, sizeof(buffer), 0);
        if (len == -1) {
            perror("recv");
            close(sockfd);
            return EXIT_FAILURE;
        }

        if (len > 0) {
            buffer[len] = '\0';
            char *str = buffer;

            while (*str) {
                printf("%s\n", str);
                str += strlen(str) + 1;
            }

            char *action = uevent_get_property(buffer, "ACTION");
            if (action) {
                printf("ACTION=%s\n", action);
            }

            char *subsystem = uevent_get_property(buffer, "SUBSYSTEM");
            if (subsystem) {
                printf("SUBSYSTEM=%s\n", subsystem);
            }
        }
    }

    close(sockfd);
    return EXIT_SUCCESS;
}

此示例代码创建一个`NETLINK_KOBJECT_UEVENT`类型的套接字，监听系统中的`uevent`事件，并使用`uevent_get_property`函数获取事件属性。每当接收到一个新事件时，程序将打印所有事件信息以及`ACTION`和`SUBSYSTEM`属性。