Linux内核的ioctl函数学习2 - linux系统ioctl使用示例

本文提供四个实用的Linux C语言程序示例：检测网络接口的IP地址、子网掩码及广播地址；检查网络接口的物理连接状态；提供一种更简单的物理连接测试方法；以及调节系统的音量。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

http://www.linuxidc.com/Linux/2007-12/9623p3.htm

These were writed and collected by kf701,
you can use and modify them but NO WARRANTY.
Contact with me : kf_701@21cn.com

程序1：检测接口的 inet_addr,netmask,broad_addr

#include <stdio.h> #include <string.h> #include <stdlib.h> #include <errno.h> #include <unistd.h> #include <sys/types.h> #include <sys/socket.h> #include <netinet/in.h> #include <arpa/inet.h> #include <sys/ioctl.h> #include <net/if.h> static void usage(){ printf("usage : ipconfig interface /n"); exit(0); } int main(int argc,char **argv) { struct sockaddr_in *addr; struct ifreq ifr; char *name,*address; int sockfd; if(argc != 2) usage(); else name = argv[1]; sockfd = socket(AF_INET,SOCK_DGRAM,0); strncpy(ifr.ifr_name,name,IFNAMSIZ-1); if(ioctl(sockfd,SIOCGIFADDR,&ifr) == -1) perror("ioctl error"),exit(1); addr = (struct sockaddr_in *)&(ifr.ifr_addr); address = inet_ntoa(addr->sin_addr); printf("inet addr: %s ",address); if(ioctl(sockfd,SIOCGIFBRDADDR,&ifr) == -1) perror("ioctl error"),exit(1); addr = (struct sockaddr_in *)&ifr.ifr_broadaddr; address = inet_ntoa(addr->sin_addr); printf("broad addr: %s ",address); if(ioctl(sockfd,SIOCGIFNETMASK,&ifr) == -1) perror("ioctl error"),exit(1); addr = (struct sockaddr_in *)&ifr.ifr_addr; address = inet_ntoa(addr->sin_addr); printf("inet mask: %s ",address); printf("/n"); exit(0); }

程序2：检查接口的物理连接是否正常

#include <stdio.h> #include <string.h> #include <errno.h> #include <fcntl.h> #include <getopt.h> #include <sys/socket.h> #include <sys/ioctl.h> #include <net/if.h> #include <stdlib.h> #include <unistd.h> typedef unsigned short u16; typedef unsigned int u32; typedef unsigned char u8; #include <linux/ethtool.h> #include <linux/sockios.h> int detect_mii(int skfd, char *ifname) { struct ifreq ifr; u16 *data, mii_val; unsigned phy_id; /* Get the vitals from the interface. */ strncpy(ifr.ifr_name, ifname, IFNAMSIZ); if (ioctl(skfd, SIOCGMIIPHY, &ifr) < 0) { fprintf(stderr, "SIOCGMIIPHY on %s failed: %s/n", ifname, strerror(errno)); (void) close(skfd); return 2; } data = (u16 *)(&ifr.ifr_data); phy_id = data[0]; data[1] = 1; if (ioctl(skfd, SIOCGMIIREG, &ifr) < 0) { fprintf(stderr, "SIOCGMIIREG on %s failed: %s/n", ifr.ifr_name, strerror(errno)); return 2; } mii_val = data[3]; return(((mii_val & 0x0016) == 0x0004) ? 0 : 1); } int detect_ethtool(int skfd, char *ifname) { struct ifreq ifr; struct ethtool_value edata; memset(&ifr, 0, sizeof(ifr)); edata.cmd = ETHTOOL_GLINK; strncpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name)-1); ifr.ifr_data = (char *) &edata; if (ioctl(skfd, SIOCETHTOOL, &ifr) == -1) { printf("ETHTOOL_GLINK failed: %s/n", strerror(errno)); return 2; } return (edata.data ? 0 : 1); } int main(int argc, char **argv) { int skfd = -1; char *ifname; int retval; if( argv[1] ) ifname = argv[1]; else ifname = "eth0"; /* Open a socket. */ if (( skfd = socket( AF_INET, SOCK_DGRAM, 0 ) ) < 0 ) { printf("socket error/n"); exit(-1); } retval = detect_ethtool(skfd, ifname); if (retval == 2) retval = detect_mii(skfd, ifname); close(skfd); if (retval == 2) printf("Could not determine status/n"); if (retval == 1) printf("Link down/n"); if (retval == 0) printf("Link up/n"); return retval; }

程序3：更简单一点测试物理连接

#include <stdio.h> #include <stdlib.h> #include <string.h> #include <errno.h> #include <net/if.h> #include <linux/sockios.h> #include <sys/ioctl.h> #define LINKTEST_GLINK 0x0000000a struct linktest_value { unsigned int cmd; unsigned int data; }; static void usage(const char * pname) { fprintf(stderr, "usage: %s <device>/n", pname); fprintf(stderr, "returns: /n"); fprintf(stderr, "/t 0: link detected/n"); fprintf(stderr, "/t%d: %s/n", ENODEV, strerror(ENODEV)); fprintf(stderr, "/t%d: %s/n", ENONET, strerror(ENONET)); fprintf(stderr, "/t%d: %s/n", EOPNOTSUPP, strerror(EOPNOTSUPP)); exit(EXIT_FAILURE); } static int linktest(const char * devname) { struct ifreq ifr; struct linktest_value edata; int fd; /* setup our control structures. */ memset(&ifr, 0, sizeof(ifr)); strcpy(ifr.ifr_name, devname); /* open control socket. */ fd=socket(AF_INET, SOCK_DGRAM, 0); if(fd < 0 ) { return -ECOMM; } errno=0; edata.cmd = LINKTEST_GLINK; ifr.ifr_data = (caddr_t)&edata; if(!ioctl(fd, SIOCETHTOOL, &ifr)) { if(edata.data) { fprintf(stdout, "link detected on %s/n", devname); return 0; } else { errno=ENONET; } } perror("linktest"); return errno; } int main(int argc, char *argv[]) { if(argc != 2) { usage(argv[0]); } return linktest(argv[1]); }

程序4：调节音量

#include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #include <sys/ioctl.h> #include <sys/soundcard.h> #include <stdio.h> #include <unistd.h> #include <math.h> #include <string.h> #include <stdlib.h> #define BASE_VALUE 257 int main(int argc,char *argv[]) { int mixer_fd=0; char *names[SOUND_MIXER_NRDEVICES]=SOUND_DEVICE_LABELS; int value,i; printf("/nusage:%s dev_no.[0..24] value[0..100]/n/n",argv[0]); printf("eg. %s 0 100/n",argv[0]); printf(" will change the volume to MAX volume./n/n"); printf("The dev_no. are as below:/n"); for (i=0;i<SOUND_MIXER_NRDEVICES;i++){ if (i%3==0) printf("/n"); printf("%s:%d/t/t",names[i],i); } printf("/n/n"); if (argc<3) exit(1); if ((mixer_fd = open("/dev/mixer",O_RDWR))){ printf("Mixer opened successfully,working.../n"); value=BASE_VALUE*atoi(argv[2]); if (ioctl(mixer_fd,MIXER_WRITE(atoi(argv[1])),&value)==0) printf("successfully....."); else printf("unsuccessfully....."); printf("done./n"); }else printf("can't open /dev/mixer error..../n"); exit(0); }