undelete.c

LINUX内核中实现“回收站”。

/*
	undelete.c
	by Liu Tao 0244072
  	version 2.77
*/

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <dirent.h>
#include <sys/stat.h>
#include "error.h"
#include "fcntl.h"
#include "sys/time.h"

//#define _DEBUG

#define _DATA_FILE "/trash/data.xml"
#define _DATA_TMP "/trash/data~.xml"
#define _LINE_LEN 256

int uid;
char currentDir[50]; 
char fileName[50];

char undelName[50];
int exist = 0;
int flag =0;
char old_path[100];
char trash[50] = "/trash/";
struct timeval date1;
long int fileID=0;

int compare(const void *s1, const void *s2)
{
	char *t1 = (char *)s1;
	char *t2 = (char *)s2;
	return strcmp(t1, t2);
}

void do_undelete(char name[100]){

     char ch;                /* char in and out */
     int source, destination; /* file fd */
     int r_count,w_count;
     strcat(trash,name);
     strcpy(name,trash);

     if (flag==1)
     {
	int j = mkdir(old_path,0);
	int k = rmdir(name);
     }
     else if (flag ==0){
   		if ( (source=open(name,O_RDONLY)) == -1)
		{
  		  	 printf( "Can't open file %s!\n", name );
  		   	 return;
  		}
  		if( (destination = open(old_path,O_APPEND | O_CREAT |O_WRONLY,0100644)) == -1)
		{
    		  	 printf( "Can't put file!\n",old_path);
    		         return;
   		}
		do 
		{
			r_count = read(source,&ch,1);
			if (r_count != 0) w_count = write(destination,&ch,1);
		}
		while(r_count!=0);
		
		int i = unlink(name);

   		close( source );
   		if( close( destination )!=0)
		{
   		        printf( "Original directory %s not exist!\n",currentDir );
   		        return;
   		}
     }
}

int match(char tmp[100]){
	char *ch;
	int i,count1=0,count2=0;

        ch=strchr(tmp,'+');
        while (ch!=NULL) {
	    count1++;
            tmp[ch-tmp]='/';
            ch=strchr(ch+1,'+');
        }
	
	memcpy(old_path,tmp,100);

	ch =tmp;

	ch=strchr(tmp,'/');
        while (ch!=NULL) {
	    count2++;
	    if (count2 == count1)  
             tmp[ch-tmp]=' ';   
	    ch=strchr(ch+1,'/');         
        }

	sscanf(tmp,"%s %s",currentDir,fileName);
	
	if (strncmp(fileName,undelName,strlen(undelName)) == 0){
#ifdef _DEBUG
		printf("IN MATCH: old_path=%s,tmp=%s,currentDir=%s,fileName=%s\n",old_path,tmp,currentDir,fileName);
#endif
		return 1;
	}
	else return 0;
}

int found(char name[100]){
	int f_uid;
	long int time;
	int option;
	char tmp_dir[100];

#ifdef _DEBUG
	printf("IN FOUND: name=%s\n",name);
#endif
	
	sscanf(name,"%d-%li-%d-%s%s",&f_uid,&time,&option,tmp_dir);
	
	date1.tv_sec = time;
	date1.tv_usec = 0;

	if (f_uid == uid || uid==0) {

#ifdef _DEBUG
		printf("%d   ", f_uid);
		printf("%li   ", time);
		printf("%s", option == 0 ? "File    " : "Dir    ");
		printf("%s   ", currentDir);
		printf("%s   \n", fileName);
#endif
	
		flag = option == 0?  0 : 1;
		return match(tmp_dir);
	}
	else return 0;
}

int main(int argc, char **argv)
{
	int i, file_num;
	DIR *dirptr;	
	struct dirent *entry;
	struct stat buf;
	char file[1000][100];
	char temp[20];
	const char empty[] = "";

	if (argc!=3)
	{
		printf("Usage: undelete <file name> <file id>\n");
		return -1;
	}

	strcpy(undelName,argv[1]);
	strcpy(temp,argv[2]);
	fileID = atol(temp);

	uid = getuid();
	if (uid!=0) 
	{
		printf("Please Let Administrator Do It.\n");	
		return -1;
	}

	if((dirptr = opendir("/trash")) == NULL)
	{
		printf("Cannot open %s\n", argv[1]);
		return 0;
	}

	file_num = 0;
	while((entry = readdir(dirptr)) != NULL) strcpy(file[file_num++], entry->d_name);

	qsort(file, file_num, 100, compare);

	for(i = 2; i < file_num; i++)
	{
		strcpy(currentDir,empty); 
		strcpy(fileName,empty);
        	if (found(file[i]))
		{
#ifdef _DEBUG
			printf("Found %s\n", file[i]);
#endif
			exist = 1;
			do_undelete(file[i]);
			break;
		}
	}
	closedir(dirptr);

	//write new content to temp. xml file
	//
	FILE* f0 = fopen(_DATA_FILE, "r");
	FILE* f1 = fopen(_DATA_TMP, "w+");
	char szLine[_LINE_LEN];
	char* c;	
	do
	{
		c = fgets(szLine, _LINE_LEN, f0);
		if ((c!=NULL) && (strstr(szLine, argv[1])==NULL || strstr(szLine, argv[2])==NULL))
		{
			fprintf(f1, szLine);
		}
	}
	while (c!=NULL);
	fclose(f0), fclose(f1);
	unlink(_DATA_FILE);
	
	//copy new xml file to old name
	//
	f0 = fopen(_DATA_TMP, "r");
	f1 = fopen(_DATA_FILE, "w+");
	do
	{
		c = fgets(szLine, _LINE_LEN, f0);
		if (c!=NULL) fprintf(f1, szLine);
	}
	while (c!=NULL);
	unlink(_DATA_TMP);
	
	if (exist == 0) printf("File %s not exist!\n", undelName);
	return 0;
}

#undef _DATA_FILE
#undef _DATA_TMP
#undef _LINE_LEN
#undef _DEBUG