1、在/proc/partitions中存放着U盘的设备名称，如sda，sdb2等，以sd开头。
major 主设备号，比如一个U盘有3个分区，主设备名为sda，major为8，分区的major也为8，minor则为分区号，sda1，sda2，minor值为1 ，2
sda的minor为0，name即为设备名，连接/dev./设备名，就可以挂载到一个目录。
blocks表示物理设备逻辑块的大小
2、代码
sign_primacy函数标记首要设备
read_proc_partition读取/proc/partitions
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
typedef struct parititions_info_s
{
unsigned long nMajor;
unsigned long nMinor;
unsigned long nBlocks;
char chDeviceName[50];
int nPrimacyDeviceFlag;
}parititions_info_t;
int sign_primacy(parititions_info_t *pstuPartitionsInfo,int nDeviceNum)
{
//如 sda sda1 sda2 sda3 ,sda作为首要设备，不需要挂载
//若sda没有分区，sda需要挂载
int nLastFindMajor = -1;
int i = 0;
int j = 0;
if((NULL == pstuPartitionsInfo) ||
(nDeviceNum <= 0))
{
printf("\nparam error\n");
return -1;
}
for(i = 0; i < nDeviceNum - 1;i++)
{
if(nLastFindMajor == pstuPartitionsInfo[i].nMajor)
{
continue;
}
for(j = i + 1 ; j < nDeviceNum; j++)
{
if(pstuPartitionsInfo[i].nMajor != pstuPartitionsInfo[j].nMajor) //major相同才比较
{
break;
}
if(NULL != strstr(pstuPartitionsInfo[j].chDeviceName, pstuPartitionsInfo[i].chDeviceName))
{
pstuPartitionsInfo[i].nPrimacyDeviceFlag = 1;
nLastFindMajor = pstuPartitionsInfo[i].nMajor;
printf("\n zzh_test primacy chDeviceName=%s,nMajor[%lu] minor=%lu Flag = %d\n",
pstuPartitionsInfo[i].chDeviceName,
pstuPartitionsInfo[i].nMajor,
pstuPartitionsInfo[i].nMinor,
pstuPartitionsInfo[i].nPrimacyDeviceFlag);
break;
}
}
}
return 0;
}
int read_proc_partition(parititions_info_t * pstuPartitionsInfo,int nMaxNum,int *pnNum)
{
FILE *fp = NULL;
int ret = -1;
int i = 0;
int nSscanfNum = 0;
unsigned long nMajor = 0;
unsigned long nMinor = 0;
unsigned long nBlocks = 0;
char chDeviceName[50] = {0};
char chBuffer[1024] = {0};
int nDeviceNum = 0;
int nFindDeviceFlag = 0;
if(NULL == pstuPartitionsInfo ||
NULL == pnNum)
{
printf("\n param error \n");
return -1;
}
fp = fopen("/proc/partitions","r");
if (NULL == fp)
{
printf("\n fopen /proc/partitions failed \n");
return -1;
}
while(1)
{
nFindDeviceFlag = 0;
memset(chBuffer,0,sizeof(chBuffer));
if(NULL == fgets(chBuffer,sizeof(chBuffer),fp))
{
break;
}
memset(chDeviceName,0,sizeof(chDeviceName));
nSscanfNum = sscanf(chBuffer ," %lu %lu %lu %[^\n]",&nMajor,&nMinor,&nBlocks,chDeviceName);
if(4 != nSscanfNum)
{
continue;
}
if(0 != strncmp(chDeviceName,"sd",strlen("sd")))
{
continue;
}
memset(&pstuPartitionsInfo[nDeviceNum], 0, sizeof(parititions_info_t));
strncpy(pstuPartitionsInfo[nDeviceNum].chDeviceName,chDeviceName,sizeof(pstuPartitionsInfo[nDeviceNum].chDeviceName) -1);
pstuPartitionsInfo[nDeviceNum].nMajor = nMajor;
pstuPartitionsInfo[nDeviceNum].nMinor = nMinor;
pstuPartitionsInfo[nDeviceNum].nBlocks = nBlocks;
printf("\n nMajor[%lu], nMinor[%lu], nBlocks[%lu], chDeviceName[%s] \n",nMajor,nMinor,nBlocks,chDeviceName);
//find device
nDeviceNum++;
if(nDeviceNum >= nMaxNum)//最多处理nMaxNum个
{
fclose(fp);
*pnNum = nDeviceNum;
sign_primacy( pstuPartitionsInfo,nDeviceNum);
return 0;
}
}
fclose(fp);
*pnNum = nDeviceNum;
if(nDeviceNum > 0)
{
sign_primacy( pstuPartitionsInfo,nDeviceNum);
}
return 0;
}
int main()
{
parititions_info_t stuPartitionsInfo[30] = {0};
int nMaxNum = sizeof(stuPartitionsInfo)/sizeof(stuPartitionsInfo[0]);
int nNum = 0;
read_proc_partition( stuPartitionsInfo, nMaxNum, &nNum);
printf("\n Num[%d] \n",nNum);
}
运行结果：
