FAT文件系统磁盘IO读取（vc实现）

#include "dir.h" #include <iostream> #include <string> CDir::CDir(Fat *fat) { _fat = fat; _rootdir_start_sector = fat->get_sectors_before_fat() + fat->get_fat_nums() * fat->get_fat_sectornums(); _rootdir_sectors = fat->get_rootentrys_nums() * 32 / fat->get_sector_bytes(); _fat0_start_sector = fat->get_sectors_before_fat(); _fat1_start_sector = _fat0_start_sector + fat->get_fat_sectornums(); _other_start = _rootdir_start_sector+_rootdir_sectors; } void CDir::_show_dir(int from, int n) { unsigned char * buffer = new unsigned char[_fat->get_sector_bytes()]; for(int i=0; i<n; i++,from++){ if(!_fat->sectorRead(from,buffer)){ std::cout<<"读取第"<<from<<"块dir失败\n"; delete [] buffer; return; } int dirs_persec = _fat->get_sector_bytes() / 32; Dir32 * pDir; //一个buffer中有16个目录项，挨个赋值给Dir结构，解析目录 unsigned char * tmp = buffer; char filename[9]; char exname[4]; for(int j=0; j< dirs_persec; j++,tmp += 32){ pDir = (Dir32 *)tmp; unsigned char first = (unsigned char)pDir->filename[0]; //卷标不显示 if(pDir->property.volume == 1) continue; if(first != 0xe5 && first != 0x0){ //文件名和扩展名都不是以'\0'结尾的字符串,需要转换 _char_to_string(pDir->filename,filename,8); if(first == 0x05) filename[0] = (char)0xe5; _char_to_string(pDir->exname,exname,3); std::cout<<filename; if(pDir->property.dir ==1) std::cout<<"\t<dir>"; else std::cout<<"\t"<<exname; //时间从1980年开始 std::cout<<"\t"<<pDir->date.year+1980<<"."<<pDir->date.month<<"."<<pDir->date.day; std::cout<<"\t"<<pDir->time.hour<<":"<<pDir->time.minute<<":"<<pDir->time.second; std::cout<<std::endl; } } } delete [] buffer; } void CDir::show_rootdir() { _show_dir(_rootdir_start_sector, _rootdir_sectors); } EntryPos CDir::_find_file(std::string name) { //跟前面的代码dup的太多了，不知道怎么才能复用 unsigned char *buffer = new unsigned char[_fat->get_sector_bytes()]; int from = _rootdir_start_sector; int n = _rootdir_sectors; EntryPos entrypos; entrypos.sector = -1; entrypos.offset = -1; for(int i=0; i<n; i++,from++){ if(!_fat->sectorRead(from,buffer)){ std::cout<<"读取第"<<from<<"块dir失败\n"; delete [] buffer; return entrypos; } int dirs_persec = _fat->get_sector_bytes() / 32; Dir32 * pDir; unsigned char * tmp = buffer; char filename[9]; char exname[4]; for(int j=0; j< dirs_persec; j++,tmp += 32){ pDir = (Dir32 *)tmp; _char_to_string(pDir->filename,filename,8); _char_to_string(pDir->exname,exname,3); std::string strname =""; strname += filename; strname +="."; strname +=exname; //不能区分大小写 if(strcmp(strlwr((char *)strname.c_str()),strlwr((char *)name.c_str())) == 0){ entrypos.sector = from; entrypos.offset = j; delete [] buffer; return entrypos; } } } delete [] buffer; return entrypos; } void CDir::_char_to_string(char *s,char *d,int n) { for(int k =0; k<n; k++){ if((unsigned char )s[k] == 0x20){ d[k]='\0'; return; } d[k]=s[k]; } d[n] = '\0'; } void CDir::change_name(std::string sname,std::string dname) { EntryPos entrpos = _find_file(sname); if(entrpos.sector < 0 || entrpos.offset < 0){ std::cout<<"文件"<<sname<<"不存在\n"; return; } EntryPos entrpos2 = _find_file(dname); if(entrpos2.sector > 0 && entrpos2.offset >= 0){ std::cout<<"文件"<<dname<<"已经存在\n"; return; } unsigned char *buffer = new unsigned char[12]; unsigned char *tmp = buffer; int index = dname.find_first_of('.'); //文件名 int offset = entrpos.offset*32; strcpy((char *)tmp,dname.substr(0,index).c_str()); strupr( (char*)tmp); //扩展名 tmp += 8; strcpy((char*)tmp,dname.substr(index+1,3).c_str()); strupr((char *)tmp); //少于8字节的名字用0x20补齐 for(int i=index;i<8;i++) buffer[i] = 0x20; _fat->sectorWrite(entrpos.sector,buffer,offset,11); delete [] buffer; } void CDir::del_file(std::string sname) { EntryPos entrypos = _find_file(sname); if(entrypos.offset<0 || entrypos.sector <0){ std::cout<<"文件"<<sname<<"不存在\n"; return; } unsigned char * buffer = new unsigned char[_fat->get_sector_bytes()]; _fat->sectorRead(entrypos.sector,buffer); //定位目录项 unsigned char * p = buffer; p += entrypos.offset * 32; Dir32 * pDir; pDir = (Dir32 *)p; pDir->filename[0]=(unsigned char)0xe5; _del_fat12(pDir->start_cluster,_fat0_start_sector); _del_fat12(pDir->start_cluster,_fat1_start_sector); _fat->sectorWrite(entrypos.sector,(unsigned char *)pDir,entrypos.offset*32,32); delete [] buffer; } void CDir::_del_fat12(int start_cluster,int fat_start_sector) { unsigned char *buffer = new unsigned char [_fat->get_sector_bytes()]; int cur_cluster = start_cluster; while(1){ //0空闲，0xff7坏道，0x8ff--0xfff结束 if(cur_cluster == 0x0 || cur_cluster >0xff7 && cur_cluster<0xfff) break; Fat12_Return fatReturn = _find_fat12_cluster(cur_cluster,fat_start_sector); Fat12_Entry *pfat12entry = &fatReturn.entry; int n = fatReturn.n; int offset = fatReturn.offset; int sector = fatReturn.sector; if(cur_cluster %2 == 0){ cur_cluster = pfat12entry->entry0; pfat12entry->entry0 =0x0; } else{ cur_cluster = pfat12entry->entry1; pfat12entry->entry1 = 0x0; } if(n<3){ _fat->sectorWrite(sector,(unsigned char*)pfat12entry,offset,n); _fat->sectorWrite(sector+1,(unsigned char*)(pfat12entry + n),0,3-n); } else _fat->sectorWrite(sector,(unsigned char*)pfat12entry,offset,3); } delete [] buffer; return; } void CDir::copy_file(std::string sname,std::string dname) { EntryPos entrpos = _find_file(sname); if(entrpos.sector < 0 || entrpos.offset < 0){ std::cout<<"文件"<<sname<<"不存在\n"; return; } EntryPos entrpos2 = _find_file(dname); if(entrpos2.sector > 0 && entrpos2.offset >= 0){ std::cout<<"文件"<<dname<<"已经存在\n"; return; } int sCluster = _find_fat12_entry(entrpos); EntryPos dEntrypos = _add_dir_entry(entrpos,dname); int dCluster = _find_fat12_entry(dEntrypos); _copy_file(sCluster,dCluster,_fat0_start_sector); } void CDir::_copy_file(int sCluster,int dCluster,int fat_start_sector) { int sCur_cluster = sCluster; int dCur_cluster = dCluster; while(1){ //0空闲，0xff7坏道，0x8ff--0xfff结束 if(sCur_cluster == 0x0 || sCur_cluster >=0xff7 && sCur_cluster<=0xfff) return; //fat中的第二项对应文件中的第0项 for(int i=0;i<_fat->get_sector_PerCluster();i++) _fat->sectorCopy(_other_start-2 + sCluster+i, 0,_other_start-2 + dCur_cluster+i,0,_fat->get_sector_bytes()); Fat12_Return sFatReturn = _find_fat12_cluster(sCur_cluster,fat_start_sector); if(sCur_cluster %2 == 0) sCur_cluster = sFatReturn.entry.entry0; else sCur_cluster = sFatReturn.entry.entry1; int new_dCluster = _find_bank_fat12_entry(); Fat12_Return dFatReturn = _find_fat12_cluster(dCur_cluster,fat_start_sector); //建立链表 if(dCur_cluster %2 == 0) dFatReturn.entry.entry0 = new_dCluster; else dFatReturn.entry.entry1 = new_dCluster; dCur_cluster = new_dCluster; if(dFatReturn.n<3){ _fat->sectorWrite(dFatReturn.sector,(unsigned char*)&dFatReturn.entry ,dFatReturn.offset,dFatReturn.n); _fat->sectorWrite(dFatReturn.sector+1,(unsigned char*)(&dFatReturn.entry + dFatReturn.n),0,3-dFatReturn.n); } else _fat->sectorWrite(dFatReturn.sector,(unsigned char*)&dFatReturn.entry,dFatReturn.offset,3); } } Fat12_Return CDir::_find_fat12_cluster(int cur_cluster,int fat_start_sector) {//定位fat12文件的文件项偏移未知真是麻烦，都格式化无数次软盘了 unsigned char * fat_entry = new unsigned char[sizeof(Fat12_Entry )]; unsigned char *buffer = new unsigned char [_fat->get_sector_bytes()]; int sector = _get_fat12_entry_sector(cur_cluster) + fat_start_sector; //offset是偏移字节数 //求of