标签：课程设计 操作系统 int 源码 fd hashfile buf sizeof struct
#include <unistd.h>
#define COLLISIONFACTOR 0.5 //Hash函数冲突因子
struct HashFileHeader
{
int sig; //Hash文件印鉴
int reclen; //记录长度
int total_rec_num; //总记录数
int current_rec_num; //当前记录数
};
struct CFTag
{
char collision; //冲突计数
char free; //空闲标志
};
int hashfile_creat(const char *filename,mode_t mode,int reclen,int recnum);
//int hashfile_open(const char *filename,int flags);
int hashfile_open(const char *filename,int flags, mode_t mode);
int hashfile_close(int fd);
int hashfile_read(int fd,int keyoffset,int keylen,void *buf);
int hashfile_write(int fd,int keyoffset,int keylen,void *buf);
int hashfile_delrec(int fd,int keyoffset,int keylen,void *buf);
int hashfile_findrec(int fd,int keyoffset,int keylen,void *buf);
int hashfile_saverec(int fd,int keyoffset,int keylen,void *buf);
int hash(int keyoffset,int keylen,void *buf,int recnum);
int checkHashFileFull(int fd);
int readHashFileHeader(int fd,struct HashFileHeader *hfh )
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdio.h>
#include "HashFile.h"
int hashfile_creat(const char *filename,mode_t mode,int reclen,int total_rec_num)
{
struct HashFileHeader hfh;
int fd;
int rtn;
char *buf;
int i=0;
hfh.sig=31415926;
hfh.reclen=reclen;
hfh.total_rec_num=total_rec_num;
hfh.current_rec_num=0;
//fd=open(filename,mode);
fd=creat(filename,mode);
if(fd!=-1)
{
rtn=write(fd,&hfh,sizeof(struct HashFileHeader));
//lseek(fd,sizeof(struct HashFileHeader),SEEK_SET);
if(rtn!=-1)
{
buf=(char*)malloc((reclen+sizeof(struct CFTag))*total_rec_num);
memset(buf,0,(reclen+sizeof(struct CFTag))*total_rec_num);
rtn=write(fd,buf,(reclen+sizeof(struct CFTag))*total_rec_num);
free(buf);
}
close(fd);
return rtn;
}
else
{
close(fd);
return -1;
}
}
int hashfile_open(const char *filename,int flags, mode_t mode)
{
int fd=open(filename,flags,mode);
struct HashFileHeader hfh;
if(read(fd,&hfh,sizeof(struct HashFileHeader))!=-1)
{
lseek(fd,0,SEEK_SET);
if(hfh.sig==31415926)
return fd;
else
return -1;
}
else
return -1;
}
int hashfile_close(int fd)
{
return close(fd);
}
int hashfile_read(int fd,int keyoffset,int keylen,void *buf)
{
struct HashFileHeader hfh;
readHashFileHeader(fd,&hfh);
int offset=hashfile_findrec(fd,keyoffset,keylen,buf);
if(offset!=-1)
{
lseek(fd,offset+sizeof(struct CFTag),SEEK_SET);
return read(fd,buf,hfh.reclen);
}
else
{
return -1;
}
}
int hashfile_write(int fd,int keyoffset,int keylen,void *buf)
{
return hashfile_saverec(fd,keyoffset,keylen,buf);
//return -1;
}
int hashfile_delrec(int fd,int keyoffset,int keylen,void *buf)
{
int offset;
offset=hashfile_findrec(fd,keyoffset,keylen,buf);
if(offset!=-1)
{
struct CFTag tag;
read(fd,&tag,sizeof(struct CFTag));
tag.free=0; //置空闲标志
lseek(fd,offset,SEEK_SET);
write(fd,&tag,sizeof(struct CFTag));
struct HashFileHeader hfh;
readHashFileHeader(fd,&hfh);
int addr=hash(keyoffset,keylen,buf,hfh.total_rec_num);
offset=sizeof(struct HashFileHeader)+addr*(hfh.reclen+sizeof(struct CFTag));
if(lseek(fd,offset,SEEK_SET)==-1)
return -1;
read(fd,&tag,sizeof(struct CFTag));
tag.collision--; //冲突记数减1
lseek(fd,offset,SEEK_SET); //
write(fd,&tag,sizeof(struct CFTag));
hfh.current_rec_num--; //当前记录数减1
lseek(fd,0,SEEK_SET);
write(fd,&hfh,sizeof(struct HashFileHeader));
}
else
{
return -1;
}
}
int hashfile_findrec(int fd,int keyoffset,int keylen,void *buf)
{
struct HashFileHeader hfh;
readHashFileHeader(fd,&hfh);
int addr=hash(keyoffset,keylen,buf,hfh.total_rec_num);
int offset=sizeof(struct HashFileHeader)+addr*(hfh.reclen+sizeof(struct CFTag));
if(lseek(fd,offset,SEEK_SET)==-1)
return -1;
struct CFTag tag;
read(fd,&tag,sizeof(struct CFTag));
char count=tag.collision;
if(count==0)
return -1; //不存在
recfree:
if(tag.free==0)
{
offset+=hfh.reclen+sizeof(struct CFTag);
if(lseek(fd,offset,SEEK_SET)==-1)
return -1;
read(fd,&tag,sizeof(struct CFTag));
goto recfree;
}
else
{
char *p=(char*)malloc(hfh.reclen*sizeof(char));
read(fd,p,hfh.reclen);
//printf("Record is {%d,%s}\n",((struct jtRecord*)p)->key,((struct jtRecord*)p)->other);
char *p1,*p2;
p1=(char*)buf+keyoffset;
p2=p+keyoffset;
int j=0;
while((*p1==*p2)&&(j<keylen))
{
p1++;
p2++;
j++;
}
if(j==keylen)
{
free(p);
p=NULL;
return (offset); //找到,返回偏移值
}
else
{
if(addr==hash(keyoffset,keylen,p,hfh.total_rec_num))
{
count--; //hash值相等而key值不等
if(count==0)
{
free(p);
p=NULL;
return -1; //不存在
}
}
free(p);
p=NULL;
offset+=hfh.reclen+sizeof(struct CFTag);
if(lseek(fd,offset,SEEK_SET)==-1)
return -1;
read(fd,&tag,sizeof(struct CFTag));
goto recfree;
}
}
}
int hashfile_saverec(int fd,int keyoffset,int keylen,void *buf)
{
if(checkHashFileFull(fd))
{
return -1;
}
struct HashFileHeader hfh;
readHashFileHeader(fd,&hfh);
int addr=hash(keyoffset,keylen,buf,hfh.total_rec_num);
int offset=sizeof(struct HashFileHeader)+addr*(hfh.reclen+sizeof(struct CFTag));
if(lseek(fd,offset,SEEK_SET)==-1)
return -1;
struct CFTag tag;
read(fd,&tag,sizeof(struct CFTag));
tag.collision++;
lseek(fd,sizeof(struct CFTag)*(-1),SEEK_CUR);
write(fd,&tag,sizeof(struct CFTag));
while(tag.free!=0) //冲突，顺序探查
{
offset+=hfh.reclen+sizeof(struct CFTag);
if(offset>=lseek(fd,0,SEEK_END))
offset=sizeof(struct HashFileHeader);//reach at end,then rewind
if(lseek(fd,offset,SEEK_SET)==-1)
return -1;
read(fd,&tag,sizeof(struct CFTag));
}
tag.free=1;
lseek(fd,sizeof(struct CFTag)*(-1),SEEK_CUR);
write(fd,&tag,sizeof(struct CFTag));
write(fd,buf,hfh.reclen);
hfh.current_rec_num++; //当前记录数加1
lseek(fd,0,SEEK_SET);
return write(fd,&hfh,sizeof(struct HashFileHeader)); //存入记录
}
int hash(int keyoffset,int keylen,void *buf,int total_rec_num)
{
int i=0;
char *p=(char *)buf+keyoffset;
int addr=0;
for(i=0;i<keylen;i++)
{
addr+=(int)(*p);
p++;
}
return addr%(int)(total_rec_num*COLLISIONFACTOR);
}
int readHashFileHeader(int fd,struct HashFileHeader *hfh )
{
lseek(fd,0,SEEK_SET);
return read(fd,hfh,sizeof(struct HashFileHeader));
}
int checkHashFileFull(int fd)
{
struct HashFileHeader hfh;
readHashFileHeader(fd,&hfh);
if(hfh.current_rec_num<hfh.total_rec_num)
return 0;
else
return 1;
#define RECORDLEN 32
struct jtRecord
{
int key;
char other[RECORDLEN-sizeof(int)];
};
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include <stdio.h>
#include <stdlib.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <string.h>
#include "HashFile.h"
#include "jtRecord.h"
#define KEYOFFSET 0
#define KEYLEN sizeof(int)
#define FILENAME "jing.hash"
void showHashFile();
int main(int argc, char *argv[])
{
struct jtRecord rec[6]=
{
{
1,"jing"
}
,{2,"wang"},{3,"li"},{4,"zhang"},{5,"qing"},{6,"yuan"}
};
int j=0;
for(j=0;j<6;j++)
{
printf("<%d,%d>\t",rec[j].key,hash(KEYOFFSET,KEYLEN,&rec[j],6));
}
int fd=hashfile_creat(FILENAME,O_RDWR|O_CREAT,RECORDLEN,6);
int i=0;
printf("\nOpen ans Save Record...\n");
fd=hashfile_open(FILENAME,O_RDWR,0);
for(i=0;i<6;i++)
{
hashfile_saverec(fd,KEYOFFSET,KEYLEN,&rec[i]);
}
hashfile_close(fd);
showHashFile();
//Demo find Rec
printf("\nFind Record...");
fd=hashfile_open(FILENAME,O_RDWR,0);
int offset=hashfile_findrec(fd,KEYOFFSET,KEYLEN,&rec[4]);
printf("\noffset is %d\n",offset);
hashfile_close(fd);
struct jtRecord jt;
struct CFTag tag;
fd=open(FILENAME,O_RDWR);
lseek(fd,offset,SEEK_SET);
read(fd,&tag,sizeof(struct CFTag));
printf("Tag is <%d,%d>\t",tag.collision,tag.free);
read(fd,&jt,sizeof(struct jtRecord));
printf("Record is {%d,%s}\n",jt.key,jt.other);
//Demo Delete Rec
printf("\nDelete Record...");
fd=hashfile_open(FILENAME,O_RDWR,0);
hashfile_delrec(fd,KEYOFFSET,KEYLEN,&rec[2]);
hashfile_close(fd);
showHashFile();
//Demo Read
fd=hashfile_open(FILENAME,O_RDWR,0);
char buf[32];
memcpy(buf,&rec[1],KEYLEN);
hashfile_read(fd,KEYOFFSET,KEYLEN,buf);
printf("\nRead Record is {%d,%s}\n",((struct jtRecord*)buf)->key,((struct jtRecord*)buf)->other);
hashfile_close(fd);
//Demo Write
printf("\nWrite Record...");
fd=hashfile_open(FILENAME,O_RDWR,0);
hashfile_write(fd,KEYOFFSET,KEYLEN,&rec[3]);
hashfile_close(fd);
showHashFile();
return 0;
}
void showHashFile()
{
int fd;
printf("\n");
fd=open(FILENAME,O_RDWR);
lseek(fd,sizeof(struct HashFileHeader),SEEK_SET);
struct jtRecord jt;
struct CFTag tag;
while(1)
{
if (read(fd,&tag,sizeof(struct CFTag))<=0)
break;
printf("Tag is <%d,%d>\t",tag.collision,tag.free);
if(read(fd,&jt,sizeof(struct jtRecord))<=0)
break;
printf("Record is {%d,%s}\n",jt.key,jt.other);
}
close(fd);
}
标签：课程设计,操作系统,int,源码,fd,hashfile,buf,sizeof,struct 来源： https://www.cnblogs.com/cckong/p/13091133.html
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