Linux系统环境下如何获得U盘拔插的信息

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获得U盘的插入或者拔取得信息的传统方法是在内核级运行hotplug程序，相关参数通过环境变量传递过来，再由hotplug通知其他关注hotplug的应用程序。这样的做法效率有些低，现在通过一种特殊类型的socket netlink实现获取U盘拔插的信息。netlink专门用于内核空间和用户空间的异步通信。

下面的例子可以监听内核的hotplug事件，源代码如下：

#include <stdio.h>#include <stdlib.h>#include <string.h>#include <ctype.h>#include <sys/un.h>#include <sys/ioctl.h>#include <sys/socket.h>#include <linux/types.h>#include <linux/netlink.h>#include <errno.h>#define UEVENT_BUFFER_SIZE 2048static int init_hotplug_sock(void);int main(int argc, char* argv[]){int hotplug_sock = init_hotplug_sock();while(1){char buf[UEVENT_BUFFER_SIZE*2] = {0};recv(hotplug_sock, &buf, sizeof(buf), 0); printf(“%s\n”, buf);}return 0;}static int init_hotplug_sock(void){struct sockaddr_nl snl;const int buffersize = 16 * 1024 * 1024;int retval;memset(&snl, 0x00, sizeof(struct sockaddr_nl));snl.nl_family = AF_NETLINK;snl.nl_pid = getpid();snl.nl_groups = 1;int hotplug_sock = socket(PF_NETLINK, SOCK_DGRAM, NETLINK_KOBJECT_UEVENT);if (hotplug_sock == -1) {printf(“error getting socket: %s”, strerror(errno));return -1;}/* set receive buffersize */setsockopt(hotplug_sock, SOL_SOCKET, SO_RCVBUFFORCE, &buffersize, sizeof(buffersize));retval = bind(hotplug_sock, (struct sockaddr *) &snl, sizeof(struct sockaddr_nl));if (retval < 0) {printf(“bind failed: %s”, strerror(errno));close(hotplug_sock);hotplug_sock = -1;return -1;}return hotplug_sock;}