最新做一个WIFI应用项目。如何检测WIFI USB设备是否插上了呢？特此共享。
第一种方法，采用读取文件的方式。在linux下，任何一种设备都可看成文件。通过分析相关文件信息，可得知WIFI设备是否存在；代码示例如下：
static void WIFI_Enum_Device(void){ charbuff[1024]; FILE *fh;
/* Check if /proc/net/wireless is available */ fh = fopen(PROC_NET_WIRELESS, "r");
if(fh != NULL) { /* Success : use data from /proc/net/wireless */
/* Eat 2 lines of header */ fgets(buff, sizeof(buff), fh); fgets(buff, sizeof(buff), fh);
/* Read each device line */ while(fgets(buff, sizeof(buff), fh)) { charname[IFNAMSIZ + 1]; char *s;
/* Skip empty or almost empty lines. It seems that in some * cases fgets return a line with only a newline. */ if((buff[0] == ‘\0’) || (buff[1] == ‘\0’)) continue;
/* Extract interface name */ s = WIFI_Get_DeviceName(name, sizeof(name), buff);
if(!s) { /* Failed to parse, complain and continue */#ifndef IW_RESTRIC_ENUM fprintf(stderr, "Cannot parse " PROC_NET_DEV "\n");#else fprintf(stderr, "Cannot parse " PROC_NET_WIRELESS "\n");#endif } else /* Got it, save the name about this interface */
{//we always use the first detected device when doing first time detecting if(s_DeviceCount == 0) { if(strcmp(s_Deviceinfo.DeviceName,name)) { memset((char *)&s_Deviceinfo, 0, sizeof(DeviceInfo_t));
memcpy(s_Deviceinfo.DeviceName,name,IFNAMSIZ); } if(strlen(s_SavedDevice) == 0)//this is the first detected device when doing first time detecting, we save it memcpy(s_SavedDevice,name,IFNAMSIZ); } else {//there is more than one device, we should use the first detected if(!strcmp(s_SavedDevice,name)) { memset((char *)&s_Deviceinfo, 0, sizeof(DeviceInfo_t));
memcpy(s_Deviceinfo.DeviceName,name,IFNAMSIZ); } } s_DeviceCount++; } }
fclose(fh); } }
static char* WIFI_Get_DeviceName(char *name,/* Where to store the name */ intnsize,/* Size of name buffer */ char *buf)/* Current position in buffer */{ char *end;
/* Skip leading spaces */ while(isspace(*buf)) buf++;
#ifndef IW_RESTRIC_ENUM /* Get name up to the last ‘:’. Aliases may contain ‘:’ in them, * but the last one should be the separator */ end = strrchr(buf, ‘:’);#else /* Get name up to ": " * Note : we compare to ": " to make sure to process aliased interfaces * properly. Doesn’t work on /proc/net/dev, because it doesn’t guarantee * a ‘ ‘ after the ‘:’*/ end = strstr(buf, ": ");#endif
/* Not found ??? To big ??? */ if((end == NULL) || (((end – buf) + 1) > nsize)) return(NULL);
/* Copy */ memcpy(name, buf, (end – buf)); name[end – buf] = ‘\0’;
/* Return value currently unused, just make sure it’s non-NULL */ return(end);}
RETURN_TYPE APP_WIFI_DetectDevice(void){ char command[50] = {‘\0’}; s_DeviceCount = 0; //reset count WIFI_Enum_Device(); s_LastDeviceCount = s_DeviceCount; if(s_DeviceCount > 0) { sprintf(command,"ifconfig %s up",s_Deviceinfo.DeviceName); system(command); //boot up the device firstly return SYS_NOERROR; } else return SYS_FAILED; }
第二种方法，利用linux ioctl函数读取I/O接口的相关信息。
/****************************************************************************** Name : trid_char * APP_NetLink_GetIFFLAGS(char *NetDev )* Description : Get net interface IFFLAGS* Params : NetDev* Returns : the string of the NetDev* Author/date : Danny.Hu /2011.11.16*****************************************************************************/RETURN_TYPE APP_NetLink_GetIFFlags( trid_char *NetDev ){ int fd = -1; int InterfaceFlags; struct ifreq ifr; memset(&ifr, 0, sizeof(ifr)); strcpy(ifr.ifr_name, NetDev); fd = socket(AF_INET, SOCK_DGRAM, 0); if (fd < 0) { printf("Cannot get control socket\n"); close(fd); return SYS_FAILED; } else if( 0!=(ioctl(fd, SIOCGIFFLAGS, (char*)&ifr)) ) { printf("Cannot get Network Interface Flags!\n"); close(fd); return SYS_FAILED; } InterfaceFlags = ifr.ifr_flags; printf("<"); if ( InterfaceFlags & IFF_UP) printf("Network %s is UP, ", NetDev); if ( InterfaceFlags & IFF_BROADCAST) printf("Network %s is BCAST, ", NetDev); if ( InterfaceFlags & IFF_MULTICAST) printf("Network %s is MCAST, ", NetDev); if ( InterfaceFlags & IFF_LOOPBACK) printf("Network %s is LOOP, ", NetDev); if ( InterfaceFlags & IFF_POINTOPOINT) printf("Network %s is P2P, ", NetDev); printf(">\n"); close(fd); return SYS_NOERROR;}
昨晚多几分钟的准备，今天少几小时的麻烦。
