操作系统－－文件系统实验源代码

/* * file_system.c * * Created on: 2009-5-28 * Author: liyi */ #include <stdio.h> #include <unistd.h> #include <stdlib.h> #include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #include <string.h> #include <time.h> #include <ctype.h> #include "file_global.h" #define RevByte(low,high) ((high)<<8|(low)) #define RevWord(lowest,lower,higher,highest) ((highest)<<24|(higher)<<16|(lower)<<8|lowest) /* * 读fat表的信息，存入fatbuf[]中 */ int readFat() { if(lseek(fd,FAT_ONE_OFFSET,SEEK_SET)<0) { perror("lseek failed"); return -1; } if(read(fd,fatbuf,FAT_SIZE)<0) { perror("read failed"); return -1; } return 1; } /* * 将改变的fat表值写回fat表 */ int writeFat() { if(lseek(fd,FAT_ONE_OFFSET,SEEK_SET)<0) { perror("lseek failed"); return -1; } if(write(fd,fatbuf,FAT_SIZE)<0) { perror("read failed"); return -1; } if(lseek(fd,FAT_TWO_OFFSET,SEEK_SET)<0) { perror("lseek failed"); return -1; } if((write(fd,fatbuf,FAT_SIZE))<0) { perror("read failed"); return -1; } return 1; } /*打印启动项记录*/ void scanBootSector() { unsigned char buf[SECTOR_SIZE]; int ret,i; if((ret=read(fd,buf,SECTOR_SIZE))<0) perror("read boot sector failed"); for(i=0;i<8;i++) bdptor.Oem_name[i]=buf[i+0x03]; bdptor.Oem_name[i]='\0'; bdptor.BytesPerSector=RevByte(buf[0x0b],buf[0x0c]); bdptor.SectorsPerCluster=buf[0x0d]; bdptor.ReservedSectors=RevByte(buf[0x0e],buf[0x0f]); bdptor.FATs=buf[0x10]; bdptor.RootDirEntries=RevByte(buf[0x11],buf[0x12]); bdptor.LogicSectors=RevByte(buf[0x13],buf[0x14]); bdptor.MediaType=buf[0x15]; bdptor.SectorsPerFAT=RevByte( buf[0x16],buf[0x17]); bdptor.SectorsPerTrack=RevByte(buf[0x18],buf[0x19]); bdptor.Heads=RevByte(buf[0x1a],buf[0x1b]); bdptor.HiddenSectors=RevByte(buf[0x1c],buf[0x1d]); printf("Oem_name \t\t%s\n" "BytesPerSector \t\t%d\n" "SectorsPerCluster \t%d\n" "ReservedSector \t\t%d\n" "FATs \t\t\t%d\n" "RootDirEntries \t\t%d\n" "LogicSectors \t\t%d\n" "MediaType \t\t%d\n" "SectorPerFAT \t\t%d\n" "SectorPerTrack \t\t%d\n" "Heads \t\t\t%d\n" "HiddenSectors \t\t%d\n", bdptor.Oem_name, bdptor.BytesPerSector, bdptor.SectorsPerCluster, bdptor.ReservedSectors, bdptor.FATs, bdptor.RootDirEntries, bdptor.LogicSectors, bdptor.MediaType, bdptor.SectorsPerFAT, bdptor.SectorsPerTrack, bdptor.Heads, bdptor.HiddenSectors); } /* * 参数：entryname 类型：char * pentry 类型：Entry * * mode 类型：int，mode=1，为目录表项；mode=0，为文件 * 返回值：偏移值大于0，则成功；-1，则失败 * 功能：搜索当前目录，查找文件或目录项 */ int scanEntry(char *entryname,Entry *pentry,int mode) { int ret,offset,i; int cluster_addr; char uppername[80]; for(i=0;i<strlen(entryname);i++) uppername[i]=toupper(entryname[i]); uppername[i]='\0'; if(curdir==NULL) //扫描根目录 { if((ret=lseek(fd,ROOTDIR_OFFSET,SEEK_SET))<0) perror("lseek ROOTDIR_OFFSET failed"); offset=ROOTDIR_OFFSET; while(offset<DATA_OFFSET) { ret=getEntry(pentry); offset+=abs(ret); if(pentry->subdir==mode&&strcmp((char *)pentry->short_name,uppername)==0) return offset; } } else //扫描子目录 { cluster_addr=DATA_OFFSET+(curdir->FirstCluster-2)*CLUSTER_SIZE; if((ret=lseek(fd,cluster_addr,SEEK_SET))<0) perror("lseek cluster_addr failed"); offset=cluster_addr; while(offset<cluster_addr+CLUSTER_SIZE) { ret=getEntry(pentry); offset+=abs(ret); if(pentry->subdir==mode&&strcmp((char *)pentry->short_name,uppername)==0) return offset; } } return -1; } /* * 参数：entry，类型：Entry * * 返回值：成功，则返回偏移值；失败：返回负值 * 功能：从根目录或文件簇中得到文件表项 */ int getEntry(Entry *pentry) { int ret,i; int count=0; unsigned char buf[DIR_ENTRY_SIZE],info[2]; /*读一个目录表项，即32字节*/ if((ret=read(fd,buf,DIR_ENTRY_SIZE))<0) perror("read entry failed"); count+=ret; if(buf[0]==0xe5||buf[0]==0x00) return -1*count; else { /*长文件名，忽略掉*/ while(buf[11]==0x0f) { if((ret=read(fd,buf,DIR_ENTRY_SIZE))<0) perror("read root dir failed"); count+=ret; } /*命名格式化，注意结尾的'\0'*/ for (i=0;i<=10;i++) pentry->short_name[i]=buf[i]; pentry->short_name[i]='\0'; formatFileName(pentry->short_name); info[0]=buf[22]; info[1]=buf[23]; findTime(&(pentry->hour),&(pentry->minute),&(pentry->second),info); info[0]=buf[24]; info[1]=buf[25]; findDate(&(pentry->year),&(pentry->month),&(pentry->day),info); pentry->FirstCluster=RevByte(buf[26],buf[27]); pentry->size=RevWord(buf[28],buf[29],buf[30],buf[31]); pentry->readonly=(buf[11]&ATTR_READONLY)?1:0; pentry->hidden=(buf[11]&ATTR_HIDDEN)?1:0; pentry->system=(buf[11]&ATTR_SYSTEM)?1:0; pentry->vlabel=(buf[11]&ATTR_VLABEL)?1:0; pentry->subdir=(buf[11]&ATTR_SUBDIR)?1:0; pentry->archive=(buf[11]&ATTR_ARCHIVE)?1:0; return count; } } /*日期*/ void findDate(unsigned short *year,unsigned short *month,unsigned short *day,unsigned char info[2]) { int date; date=RevByte(info[0],info[1]); *year=((date&MASK_YEAR)>>9)+1980; *month=((date&MASK_MONTH)>>5); *day=(date&MASK_DAY); } /*时间*/ void findTime(unsigned short *hour,unsigned short *min,unsigned short *sec,unsigned char info[2]) { int time; time=RevByte(info[0],info[1]); *hour=((time&MASK_HOUR)>>11); *min=(time&MASK_MIN)>>5; *sec=(time&MASK_SEC)*2; } /*文件名格式化，便于比较*/ void formatFileName(unsigned char *name) { unsigned char *p=name; while(*p!='\0') p++; p--; while(*p==' ') p--; p++; *p='\0'; } /* * 参数：prev，类型：unsigned char * 返回值：下一簇 * 功能：在fat表中获得下一簇的位置 */ unsigned short getFatCluster(unsigned short prev) { unsigned short next; int index; index=prev*2; next=RevByte(fatbuf[index],fatbuf[index+1]); return next; } /* * 参数：cluster，类型：unsigned short * 返回值：void * 功能：清除fat表中的簇信息 */ void clearFatCluster(unsigned short cluster) { int index; index=cluster*2; fatbuf[index]=0x00; fatbuf[index+1]=0x00; } /* * 参数：mode，类型：int * 返回值：1，成功；-1，失败 * 功能：显示所要查看目录下的内容。 * 说明：mode值为0时，查看当前目录信息；mode值为1时，查看所有的非根目录信息 */ int ud_ls(int mode) { int ret,offset,cluster_addr; int i; Entry entry; unsigned char buf[DIR_ENTRY_SIZE]; if((ret=read(fd,buf,DIR_ENTRY_SIZE))<0) perror("read entry failed"); if(mode==1) { printf("All_Non-Root_dir\n"); printf("\tname\t\tdate\t\ttime\t\tcluster\tsize\tattr\n"); for(i=0;i<100;i++) { cluster_addr=DATA_OFFSET+i*CLUSTER_SIZE; if((ret=lseek(fd,cluster_addr,SEEK_SET))<0) perror("lseek cluster_addr failed"); offset=cluster_addr; /*只读一簇的内容*/ while(offset<cluster_addr+CLUSTER_SIZE) { ret=getEntry(&entry); offset+=abs(ret); if(ret>0) { printf("%16s\t" "%d-%d-%d\t" "%d:%d:%d \t" "%d\t" "%d\t" "%s\n", entry.short_name, entry.year,entry.month,entry.day, entry.hour,entry.minute,entry.second, entry.FirstCluster, entry.size, (entry.subdir)?"dir":"file"); } } } return 1; } if(curdir==NULL) printf("Root_dir\n"); else printf("%s_dir\n",curdir->short_name); printf("\tname\t\tdate\t\ttime\t\tcluster\tsize\tattr\n"); if(curdir==NULL) //显示根目录区 { /*将fd定位到根目录区的起始地址*/ if((ret=lseek(fd,ROOTDIR_OFFSET,SEEK_SET))<0) perror("lseek ROOTDIR_OFFSET failed"); offset=ROOTDIR_OFFSET; /*从根目录区开始遍历，直到数据区起始地址*/ while(offset<DATA_OFFSET) { ret=getEntry(&entry); offset+=abs(ret); if(ret>0) { printf("%16s\t" "%d-%d-%d\t" "%d:%d:%d \t" "%d\t" "%d\t" "%s\n", entry.short_name, entry.year,entry.month,entry.day, entry.hour,entry.minute,entry.second, entry.FirstCluster, entry.size, (entry.subdir)?"dir":"file"); } } } else //显示子目录 { cluster_addr=DATA_OFFSET+(curdir->FirstCluster-2)*CLUSTER_SIZE; if((ret=lseek(fd,cluster_addr,SEEK_SET)