操作系统FAT文件系统源程序

#include "fat.h" #include <stdio.h> #include <string.h> #include <stdlib.h> struct ReserveBlock sys1; struct FCBBlock *fcb; struct DirBlock fil[32],*dir;//目录项 int *fat1; char *str,*ptr; char fillchar[BlockSize]; FILE *fp; /*a、 打开文件系统 */ FILE *OPENSYS(char *filename) { int i; fp=fopen(filename,"rb+"); fread(&sys1,1,BlockSize,fp); //printf("%d %d %d %d \n",sys1.sysblocknum,sys1.resblocknum,sys1.fatblocknum,sys1.rootblocknum); fat1=(int *)malloc(sys1.sysblocknum); for(i=0;i<sys1.fatblocknum;i++) fread(fat1,sizeof(int)*sys1.sysblocknum,1,fp);//把基本的文件系统都读进来 fseek(fp,(sys1.fatblocknum+sys1.resblocknum)*BlockSize,0);//修改文件指针的位置 dir=fil;//目录指针 fread(dir,DirSize*32,1,fp); return fp; } /*b、 关闭文件系统 */ int CLOSESYS(FILE *stream) { int i; fseek(stream,sys1.resblocknum*BlockSize,0); fwrite(fat1,sizeof(int)*sys1.sysblocknum,1,stream); fseek(fp,(sys1.fatblocknum+sys1.resblocknum)*BlockSize,0); fwrite(dir,DirSize*32,1,fp); fclose(fp); return 1; } /*c、 显示目录 */ void LISTDIR(void) { int i,flag=0; for(i=0;i<32;i++) { if(fil[i].firstblockaddr!=0) { if(flag==0) printf("filename \n"); flag=1; //标示 printf("%s\n",fil[i].filename); } } } /*d、 建立文件 */ int FCREATE(char *filename) { int i,flag=0,j,k=0,flag1=0,flag2=0,a; int n,m; while(1) {a=strlen(filename);//文件名长度 if(a>10) {printf("zhe file length too long!\n"); printf("input file name again:"); scanf("%s",filename); } else break; } while(1) { for(i=0;i<32;i++) if(strcmp(filename,fil[i].filename)==0) { printf("the name already exist \n"); printf("input name again:"); flag1=1; break; } if(flag1==0) break; scanf("%s",filename); flag1=0; } for(i=(sys1.fatblocknum+sys1.resblocknum+sys1.rootblocknum);i<sys1.sysblocknum;i++) if(fat1[i]==0) flag++;//统计磁盘上为空数目 if(flag==0) { printf("ci pan yi man");//统计结果为0,则磁盘已满 return 0; } printf("kong xian kuai shu:%d\n",flag); printf("input file length:"); for(j=0;j<32;j++) if(fil[j].firstblockaddr==0) break; while(1) {scanf("%d",&dir[j].filelen);//输入目录项中文件的长度 n=(dir[j].filelen/BlockSize)+(dir[j].filelen%BlockSize?1:0); if(n<0||n>flag)//文件长度小于0或大于空闲的空间 {printf("input length too long!\n"); printf("input again:"); } else break; } for(i=(sys1.fatblocknum+sys1.resblocknum+sys1.rootblocknum);i<sys1.sysblocknum;i++)//文件内容区域 { if(fat1[i]==0) { k++; if(flag2==0) { dir[j].firstblockaddr=i+1; flag2=1; } else { if(k>=n)//n 文件长度 { fat1[m]=i+1; fat1[i]=-1; break; } else fat1[m]=i+1; } m=i; } } strcpy(dir[j].filename,filename); dir[j].filename[a]='\0'; printf("input year:"); scanf("%d",&dir[j].year); printf("input month:"); scanf("%d",&dir[j].month); printf("input day:"); scanf("%d",&dir[j].day); return (1); } /*e、 删除文件 */ int FDELETE(char *filename) {int i,j,k,n,flag=0; struct FCBBlock *p;//文件控制块指针 p=fcb; while(p) { if(strcmp(filename,fil[p->fdtblockindex].filename)==0)//目录项所在内序号 {printf("the file has open,please close it before delete !\n"); return 0; } else p=p->next; } for(i=0;i<32;i++)//查找要关闭的文件 if(strcmp(filename,fil[i].filename)==0) { flag=1; break; } if(flag==0) {printf("file cannot find!\n"); return 0; } j=fil[i].firstblockaddr; while(1) { k=fat1[j-1]; fseek(fp,(j-1)*BlockSize,0);//将指针指向文件的第一个扇区的位置 fwrite(&fillchar,1,BlockSize,fp); fat1[j-1]=0; if(k==-1) break; else j=k; } memset(&fil[i],0,DirSize); return 1; } /*f、 打开文件 */ int FOPEN(char *filename) { int i,j=0,k,flag=0; struct FCBBlock *p,*q,*r; p=fcb; for(i=0;i<32;i++) if(strcmp(filename,fil[i].filename)==0)//找到要打开的文件 { flag=1; break; } if(flag==0) {printf("file cannot find!\n"); return 0; } while(p) {j++; if(strcmp(filename,fil[p->fdtblockindex].filename)==0) { printf("zhe file has open!\n"); return 0; } q=p; p=p->next; } if(fcb==NULL) { fcb=(struct FCBBlock *)malloc(sizeof(struct FCBBlock)); fcb->fileid=j+1;//文件标示 fcb->filepos=0;//文件读写指针 fcb->next=NULL;//指向下一个文件控制指针 fcb->fdtblockindex=i; } else { r=(struct FCBBlock *)malloc(sizeof(struct FCBBlock)); r->fileid=j+1; r->filepos=0; r->next=NULL; r->fdtblockindex=i; q->next=r; } //f->next=NULL; return 1; } long FGETLEN(int fileid)//获取文件指针 { struct FCBBlock *p; p=fcb; while(p) {if(p->fileid==fileid)//寻找要找的指针 return(p->filepos); p=p->next; } printf("get faile!\n"); return(0); } /*g、 关闭文件 */ int FCLOSE(char *filename) { int flag=0; struct FCBBlock *f,*p; f=fcb; if(strcmp(filename,fil[fcb->fdtblockindex].filename)==0) { flag=1; fcb=fcb->next; p=fcb; while(p) {p->fileid-=1; p=p->next; } return flag; } p=f; f=f->next; while(f) { if(strcmp(filename,fil[f->fdtblockindex].filename)==0) { flag=1; p=f->next; //p=p->next; while(p) { p=p->next; p->fileid-=1; } free(f); return flag; } p=f; f=f->next; } if(flag==0) { printf("zhe file has not open!\n'"); return flag; } return 0; } /*h、 文件块读 */ int FREAD(char *str, int n, int fileid) { int m,i,j=0,k,l,len; char a[3]; struct FCBBlock *p; p=fcb; while(p) {if(p->fileid==fileid) break; else p=p->next; } len=fil[p->fdtblockindex].filelen;//文件长度 l=p->filepos;//文件读写指针:该块在文件的相对位置 printf("now file pos is:"); printf("%d\n",l); printf("is writing as now file pos?(y/n):"); scanf("%s",a); if(a[0]=='n'||a[0]=='N') {printf("input pos:"); while(1) {scanf("%d",&l); if(fil[p->fdtblockindex].filelen<(l+n))//？ printf("too large!\ninput again:"); else break; } } while(1) { if(n>fil[p->fdtblockindex].filelen) {printf("too large!\n"); printf("input read size,again:"); scanf("%d",&n); } else break; } str=(char *)malloc(fil[p->fdtblockindex].filelen+1); m=(len/BlockSize)+(len%BlockSize?1:0); k=fil[p->fdtblockindex].firstblockaddr; if(m>1) { fseek(fp,(k-1)*BlockSize,0); fread(str,BlockSize,1,fp); k=fat1[k-1]; for(i=1;i<(m-1);i++) {fseek(fp,fat1[k-1]*BlockSize,0); fread(&str[i*BlockSize],BlockSize,1,fp); k=fat1[k-1]; } fseek(fp,(k-1)*BlockSize,0); fread(&str[i*BlockSize],len-i*BlockSize,1,fp); } else { fseek(fp,(k-1)*BlockSize,0); fread(str,len,1,fp); } str[n+l]='\0'; if(l!=0) str=&str[l]; p->filepos=n+l; printf("%s\n",str); return 1; } /*i、 文件块写 */ void FWRITE(char *ptr, int n, int fileid) { char a[3]; long l; int m,i=0,j,k=0,num,flag=0,flag1=0,b; struct FCBBlock *p; p=fcb; while(p) {if(p->fileid==fileid) break; else p=p->next; } l=p->filepos; printf("now file pos is:"); printf("%d\n",l); printf("is writing as now file pos?(y/n):"); scanf("%s",a); if(a[0]=='n'||a[0]=='N') {printf("input pos:"); while(1) {scanf("%d",&l); if(fil[p->fdtblockindex].filelen<(l+n)) printf("too large!\ninput again:"); else break; } } j=(l/BlockSize)+(l%BlockSize?1:0); if(l==0) j=1; num=fil[p->fdtblockindex].firstblockaddr; for(i=1;i<j;i++) num=fat1[num]; do { if(flag==0) {fseek(fp,(num-1)*BlockSize+l-(i-1)*BlockSize,0); flag=1; } else