文件系统设计.doc

文件系统设计1文件系统下列几条命令LOGIN用户登陆DIR列文件目录CREATE创建文件DELETE删除文件OPEN打开文件CLOSE关闭文件READ读文件WRITE写文件列目录时要列出文件名，物理地址，保护码和文件长度。源文件可以进行读写保护。首先应确定文件系统的数据结构：主目录、子目录及活动文件等。主目录和子目录都以文件的形式存放于磁盘，这样便于查找和修改。用户创建的文件，可以编号存储于磁盘上。如：file0,file1,file2并以编号作为物理地址，在目录中进行登记。程序见下（本程序需要在c:下建一个名为osfile的目录及一个名为file的子目录）：#include"stdio.h"#include"string.h"#include"conio.h"#include"stdlib.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<MAX；i+)fpaddrnoi=0；textattr(BLACK*16|WHITE)；clrscr()；/*clearscreen*/LoginF()；/*userlogin*/clrscr()；if(loginsuc=1)/*LoginSuccessfully*/while(1)wgetchar=0；if(choiceend=1)printf("nnC:%s>",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(n<0)str0=0；returnstr；char*ltrim(char*str)/*removetheheadingblanks.*/char*rtrim(char*str)；strrev(str)；rtrim(str)；strrev(str)；returnstr；voidLoginF()/*LOGINFileSystem*/charloginameMAXNAME,loginpw9,logincpw9,str50；inti,j,flag=1；chara25；intfindout；/*loginusernotexist*/