文件系統(tǒng)設(shè)計1文件系統(tǒng)下列幾條命令LOGIN用戶登陸DIR列文件目錄CREATE創(chuàng)建文件DELETE刪除文件OPEN打開文件CLOSE關(guān)閉文件READ讀文件WRITE寫文件列目錄時要列出文件名，物理地址，保護碼和文件長度。源文件可以進行讀寫保護。首先應(yīng)確定文件系統(tǒng)的數(shù)據(jù)結(jié)構(gòu)：主目錄、子目錄及活動文件等。主目錄和子目錄都以文件的形式存放于磁盤，這樣便于查找和修改。用戶創(chuàng)建的文件，可以編號存儲于磁盤上。如：file0,file1,file2并以編號作為物理地址，在目錄中進行登記。程序見下（本程序需要在c:下建一個名為osfile的目錄及一個名為file的子目錄）：#includestdio.h#includestring.h#includeconio.h#includestdlib.h#defineMAXNAME25/*thelargestlengthofmfdname,ufdname,filename*/#defineMAXCHILD50/*thelargestchild*/#defineMAX(MAXCHILD*MAXCHILD)/*thesizeoffpaddrno*/typedefstruct/*thestructureofOSFILE*/intfpaddr；/*filephysicaladdress*/intflength；/*filelength*/intfmode；/*filemode:0-ReadOnly；1-WriteOnly；2-ReadandWrite(default)；*/charfnameMAXNAME；/*filename*/OSFILE；typedefstruct/*thestructureofOSUFD*/charufdnameMAXNAME；/*ufdname*/OSFILEufdfileMAXCHILD；/*ufdownfile*/OSUFD；typedefstruct/*thestructureofOSUFDLOGIN*/charufdnameMAXNAME；/*ufdname*/charufdpword8；/*ufdpassword*/OSUFD_LOGIN；typedefstruct/*fileopenmode*/intifopen；/*ifopen:0-close,1-open*/intopenmode；/*0-readonly,1-writeonly,2-readandwrite,3-initial*/OSUFD_OPENMODE；OSUFD*ufdMAXCHILD；/*ufdandufdownfiles*/OSUFD_LOGINufd_lp；intucount=0；/*thecountofmfdsufds*/intfcountMAXCHILD；/*thecountofufdsfiles*/intloginsuc=0；/*whetherloginsuccessfully*/charusernameMAXNAME；/*recordloginusersname22*/chardirnameMAXNAME；/*recordcurrentdirectory*/intfpaddrnoMAX；/*recordfilephysicaladdressnum*/OSUFD_OPENMODEifopenMAXCHILDMAXCHILD；/*recordfileopen/close*/intwgetchar；/*whethergetchar()*/FILE*fp_mfd,*fp_ufd,*fp_file_p,*fp_file；voidmain()inti,j,choice1；charchoice50；/*choiceoperation:dir,create,delete,open,delete,modify,read,write*/intchoiceend=1；/*whetherchoiceend*/char*rtrim(char*str)；/*removethetrailingblanks.*/char*ltrim(char*str)；/*removetheheadingblanks.*/voidLoginF()；/*LOGINFileSystem*/voidDirF()；/*DirFileSystem*/voidCdF()；/*ChangeDir*/voidCreateF()；/*CreateFile*/voidDeleteF()；/*DeleteFile*/voidModifyFM()；/*ModifyFileMode*/voidOpenF()；/*OpenFile*/voidCloseF()；/*CloseFile*/voidReadF()；/*ReadFile*/voidWriteF()；/*WriteFile*/voidQuitF()；/*QuitFileSystem*/voidhelp()；if(fp_mfd=fopen(c:osfilemfd,rb)=NULL)fp_mfd=fopen(c:osfilemfd,wb)；fclose(fp_mfd)；for(i=0；i,strupr(dirname)；elseprintf(Badcommandorfilename.nC:%s,strupr(username)；gets(choice)；strcpy(choice,ltrim(rtrim(strlwr(choice)；if(strcmp(choice,dir)=0)choice1=1；elseif(strcmp(choice,creat)=0)choice1=2；elseif(strcmp(choice,delete)=0)choice1=3；elseif(strcmp(choice,attrib)=0)choice1=4；elseif(strcmp(choice,open)=0)choice1=5；elseif(strcmp(choice,close)=0)choice1=6；elseif(strcmp(choice,read)=0)choice1=7；elseif(strcmp(choice,modify)=0)choice1=8；elseif(strcmp(choice,exit)=0)choice1=9；elseif(strcmp(choice,cls)=0)choice1=10；elseif(strcmp(choice,cd)=0)choice1=11；elseif(strcmp(choice,help)=0)choice1=20；elsechoice1=12；switch(choice1)case1:DirF()；choiceend=1；break；case2:CreateF()；choiceend=1；if(!wgetchar)getchar()；break；case3:DeleteF()；choiceend=1；if(!wgetchar)getchar()；break；case4:ModifyFM()；choiceend=1；if(!wgetchar)getchar()；break；case5:choiceend=1；OpenF()；if(!wgetchar)getchar()；break；case6:choiceend=1；CloseF()；if(!wgetchar)getchar()；break；case7:choiceend=1；ReadF()；if(!wgetchar)getchar()；break；case8:choiceend=1；WriteF()；if(!wgetchar)getchar()；break；case9:printf(nYouhaveexitedthissystem.)；QuitF()；exit(0)；break；case10:choiceend=1；clrscr()；break；case11:CdF()；choiceend=1；break；case20:help()；choiceend=1；break；default:choiceend=0；elseprintf(nAccessdenied.)；voidhelp(void)printf(nTheCommandListn)；printf(nCdAttribCreatModifyReadOpenClsDeleteExitClosen)；char*rtrim(char*str)/*removethetrailingblanks.*/intn=strlen(str)-1；while(n=0)if(*(str+n)!=)*(str+n+1)=0；break；elsen-；if(n0)str0=0；returnstr；char*ltrim(char*str)/*removetheheadingblanks.*/cha