Directory Viewer---dynamic linking and static linking

A.Third Edition

This is third edition of fourth assignment of comp229. And there is little change except that in order to

demonstrate that dynamic library is not really necessary, I moved all global variable declaration from dynamic library

to static library. Therefore, main and static library will not have to run on dependence to dynamic library. In other 

word, we can run executable file even without existence of dynamic library! (In fact it is not completely true. 

See here.)

I also corrected a small bug: When I type in option "-range a-d" and all files with starting letter "d" are not 

selected. Reason is simple: You see the range parameter with "a-d", however, if you use "strcmp" to compare 

string "d" with any file name starting with letter "d", string "d" is always smaller. So, I change the 

if (strcmp(ptr, begin)>=0 &&strcmp(ptr, end)<=0)

to 

if (ptr[0]>=begin[0]&&ptr[0]<=end[0])

B.The problem

D.The major functions

C.Further improvement

//this is main program: main.c

#include <stdio.h>

extern char* prompt;
//these are my own defined utility functions 
//this check the command of "dl" and "cd" then send all rest 
//arguments to "checkOptions()" 
extern int checkCmd(char* cmd);
 
//get user input string from keyboard and store in the parameter
extern int input(char* str);


int main()
{
	char str[256];
	write(0, prompt, strlen(prompt));
	//input will only return 0 unless "exit" met
	while (input(str))
	{
		checkCmd(str);	
		write(0, prompt, strlen(prompt));
	}
		
	return 0;
}

//this is static library program: staticLib.c

////////////////////////////////////////////////////////////////////////////
//program: Assignment 3 of comp229
//author: Qingzhe Huang
//ID: 5037735
//date: Oct. 24, 2003
//purpose of program: to use system call to implement "dv" directory viewer
///////////////////////////////////////////////////////////////////////////// 


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


//these are all functions defined in assignment and
//would be linked dynamically
extern int SelectMonth(char* month);
extern int ChangeDir(char* dir);
extern int GetAllFiles();
extern int RemoveHidden();
extern int SelectRange(char* begin, char* end);
extern int SelectDate(int date);
extern int SelectBigger(int size);
extern int SelectSmaller(int size);
extern void PrintList(char* sortby);

int sortIndex = 0;
extern int errno;
char* sortedBy[3] = {"name", "date", "size"};

enum SortBy
{ByName, ByDate, BySize};

//a record to store file info
struct FileInfo
{
	char name[31];
	long size;
	time_t  mdate;
} fileInfo[1024];

//the fileInfo counter
int infoCount =0;

//fileList stores the file index interested by user
int fileList[1024]={0};
//this is its counter
int listCount =0;




//the parameter for "SelectRange()"
char beginStr[2];
char endStr[2];

//flag for "GetAllFiles()", 1 means re-read all files which is 
//default, until set to 0 by "cd" parameter
int reRead=1;

//a simple way to change string to index, is it faster than MIA's little
//switch function "MonToStr"?
char* months[12] = {"Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", 
	"Sep", "Oct", "Nov", "Dec"};

//the command prompt for our "directory viewer"
char* prompt = "mydv: ";

//this is the directory name, cause I need to display several times
//in different functions, I have to make it global.
char buffer[256];



//these are my own defined utility functions 
//this check the command of "dl" and "cd" then send all rest 
//arguments to "checkOptions()" 
int checkCmd(char* cmd);
 
//this will collect user input lines until "exit" int input(char* str); 
//check all options and call each "selection" functions by options accordingly 
int checkOptions(char** options, int count); 

//a utility function does the printing job 
int printInfo();


//get user input string from keyboard and store in the parameter
int input(char* str);


int input(char* str)
{
	char* ptr = str;
	while (1)
	{
		read(0, ptr, 1);
		if (*ptr==10)
		{
			break;
		}
		ptr++;
	}
	*ptr = '\0';
	return strcmp(str, "exit");
}


int checkCmd(char* cmd)
{
	char* ptr = cmd;
	//is there any limit for command line parameters? Yes, I said it is 20
	//who would say no????:)
	char* options[20];
	int count = 0, i;
	pid_t pid=0;
	//if user enters nothing, it is not NULL!!!
	if (!strcmp(cmd, ""))
	{
		return 0;
	}
	//\n should also be delimiter
	while (options[count]=strtok(ptr, " \n"))
	{
		ptr = NULL;
		count++;
	}
	//then we can pass options as char**
	options[count] = NULL; //just make sure it is null at end
	//the maximum and minimum of parameters
	if (count<=11&&count>=2)
	{
		if (!strcmp(options[0], "cd"))
		{
			//I won't check all other parameters
			if (ChangeDir(options[1])==1)
			{
				reRead =1;//need re-Getallfiles
				return 1;
			}
			else
			{
				return -1;
			}
		}
		if (!strcmp(options[0], "dl"))
		{
			if (reRead)
			{
				GetAllFiles();
				//make sure all files will be read only once with 
				//multiple "dl"
				reRead =0;
			}
			//passing char** 
			return checkOptions(&options[1], count-1);
		
		}
	}
	
	//fork another process to execute whatever user input
	if ((pid = fork())==0)
	{
		execvp(options[0], options);
		printf("%s\n", strerror(errno));
		exit(-1);
	}
	//waiting utill user returns...
	wait(NULL);
	return 1;

}

int printInfo()
{
	int i=0;
	char str[23];
	struct tm* t;
	for (i=0; i<listCount; i++)
	{
		t = gmtime(&fileInfo[fileList[i]].mdate);
		sprintf(str, "%s %02d, %4d; %02d:%02d:%02d", months[t->tm_mon], t->tm_mday, 
			t->tm_year + 1900, 	t->tm_hour, t->tm_min, t->tm_sec);
		
		printf("%-30s   %8d   %s\n", fileInfo[fileList[i]].name, fileInfo[fileList[i]].size, str);
	}
}


int checkOptions(char** options, int count)
{
	int i=0;
	int result=0;
	int removeHidden=1;
	char string[256];
	//make sure there is any file
	while (i<count&&listCount)
	{
		if (!strcmp(options[i], "-range"))
		{
			if (i+1<count)
			{
				//since it is only a character
				beginStr[0] = options[i+1][0];
				beginStr[1] = '\0';
				endStr[0] = options[i+1][2];
				endStr[1] = '\0';

				listCount=SelectRange(beginStr, endStr);
				i+=2;	
				continue;
			}	
			else
			{
				printf("%s\n", "missing parameter for -range options");
				return -1;
				
			}
		}
		if (!strcmp(options[i], "-modified"))
		{
			if (i+1< count)
			{
				//this is for month
				listCount=SelectMonth(options[i+1]);
				i+=2;
			}
			else
			{
				printf("%s\n", "missing parameter for -modified options");
			    return -1;
			}

			if (i<count)
			{
				if (strcmp(options[i], "-all")&&strcmp(options[i], "-range")
					&&strcmp(options[i], "-biggerthan")&&strcmp(options[i],"-smallerthan"))
				{
					listCount=SelectDate(atoi(options[i]));
					i++;
				}
			}
			continue;
		}	
			
		if (!strcmp(options[i], "-biggerthan"))
		{
			if (i+1<count)
			{
				listCount = SelectBigger(atoi(options[i+1]));
				i+=2;
				continue;
			}
			else
			{
				printf("%s\n", "missing parameter for -biggerthan options");
				return -1;
			}
		}

		if (!strcmp(options[i], "-smallerthan"))
		{
			if (i+1<count)
			{
				listCount=SelectSmaller(atoi(options[i+1]));
				i+=2;
				continue;
			}
			else
			{
				printf("%s\n", "missing parameter for -smallerthan options");
				return -1;
			}					
		}

		if (!strcmp(options[i], "-all"))
		{
			removeHidden=0;
			i++;
			sortIndex = ByName;
			continue;
		}
		if (i==0)
		{
			printf("%s\n", "invalide parameter!");
			return -1;
		}
		i++;
	}
	if (removeHidden)
	{
		listCount = RemoveHidden();
		
	}
	//if there is no more files,
	if (!listCount)
	{
		//I cannot understand why printf doesn't work properly
		//it won't display until the function returns, so I have to 
		//use system call "write" which is very fast
		strcpy(string, "Directory ");
		strcat(string, buffer);
		strcat(string, " does not contain any files.\n");
		write(0, string, strlen(string));
//		printf("Directory %s does not contain any files.", buffer);
	}
	else
	{
		PrintList(sortedBy[sortIndex]);
		return result;
	}
}

//this is dynamic library program: dynamicLib.c

#include <sys/types.h>
#include <sys/stat.h> 
#include <stdio.h>
#include <stdlib.h> 
#include <strings.h> 
#include <unistd.h> 
#include <dirent.h> 
#include <time.h>

struct FileInfo
{
	char name[31];
	long size;
	time_t  mdate;
};

extern int fileList[1024];
extern int errno;
extern struct FileInfo fileInfo[1024];
extern int infoCount;
extern int listCount;
extern char* months[12];
extern char buffer[256];

//these are all functions defined in assignment
int SelectMonth(char* month);
int ChangeDir(char* dir);
int GetAllFiles();
int RemoveHidden();
int SelectRange(char* begin, char* end);
int SelectDate(int date);
int SelectBigger(int size);
int SelectSmaller(int size);
void PrintList(char* sortby);

enum SortBy
{ByName, ByDate, BySize};

//parameter for "PrintList()" to indicate what field to be sorted by

//the actual enum SortBy variable for index of "sortedBy[3]"
extern int sortIndex;
extern char* sortedBy[3];


//three callback function for "qsort"
int compName(const void*, const void*);
int compDate(const void*, const void*);
int compSize(const void*, const void*);

//a function pointer array so as to be used in "qsort"
int (*compFuns[3])(const void*, const void*) = {compName, compDate, compSize};


int ChangeDir(char* dir)
{
	int temp =0;
	if ((temp=chdir(dir))==-1)
	{
		printf("Directory %s does not exist.\n", dir);
		return -1;
	}
	else
	{		
		return 1;

	}
}


int GetAllFiles()
{
	char fileName[256];
	DIR *dp=NULL;
	struct dirent *d;
	struct stat s;
	
	//maybe MIA's way is simple---dir = ".";
	if (!(dp = opendir(getcwd(buffer, 256))))
	{
		printf("%s\n", strerror(errno));
		return -1;
	}
	//strcat(buffer, buffer[strlen(buffer)]=='/'?"":"/");
	infoCount=listCount=0;
	while (d=readdir(dp))
	{
		if (stat(d->d_name, &s)==-1)
		{
			printf("cannot access file %s\n", d->d_name);
			continue;
		}
		else
		{
			//we shall not select directories
			if (S_ISDIR(s.st_mode))
			{
				continue;
			}
		}
		
		if (d->d_ino!=0)
		{
			//strcpy(fileInfo[infoCount].name, buffer);
			//printf("%s\n", d->d_name);
			if (stat(d->d_name, &s)!=-1)
			{
				strcpy(fileInfo[infoCount].name, d->d_name);
				fileInfo[infoCount].size = s.st_size;
				fileInfo[infoCount].mdate = s.st_mtime;
				infoCount++;
				fileList[listCount]=listCount; //means there is an index to...
				listCount++;				
			}
				
		}
	}
	return infoCount;			
}

int SelectMonth(char* month)
{
	int i, temp=0;
	int imonth=0;//the month
	//find out the index of month
	for (i=0; i<12; i++)
	{
		if (!strcmp(month, months[i]))
		{
			imonth=i;
			break;
		}
	}

	for (i=0; i<listCount; i++)
	{
		if (gmtime(&fileInfo[fileList[i]].mdate)->tm_mon==imonth)
		{
			fileList[temp]=fileList[i];
			temp++;
		}
		
	}
	listCount = temp;
	sortIndex = ByDate;
	return listCount;
}		
		
int RemoveHidden()
{
	int i, temp=0;
	for (i=0; i<listCount; i++)
	{	
		if (fileInfo[fileList[i]].name[0]!='.')
		{
			fileList[temp]=fileList[i];
			temp++;
		}
		
	}
	listCount=temp;
	return listCount;
}		

int SelectBigger(int size)
{
	int i, temp=0;
	for (i=0; i<listCount; i++)
	{	
		if (fileInfo[fileList[i]].size>=size)
		{
			fileList[temp]=fileList[i];
			temp++;
		}		
	}
	listCount =temp;
	sortIndex = BySize;
	return listCount;
}

int SelectSmaller(int size)
{
	int i, temp=0;
	for (i=0; i<listCount; i++)
	{	
		if (fileInfo[fileList[i]].size<=size)
		{
			fileList[temp]=fileList[i];
			temp++;
		}		
	}
	listCount =temp;
	sortIndex = BySize;
	return listCount;
}
	
int SelectRange(char* begin, char* end)
{
	int i, temp=0;
	char* ptr;
	for (i=0; i<listCount; i++)
	{	
		if (fileInfo[fileList[i]].name[0]=='.')
		{
			ptr = fileInfo[fileList[i]].name + 1;
		}
		else
		{
			ptr = fileInfo[fileList[i]].name;
		}

//		if (strcmp(ptr, begin)>=0
//			&&strcmp(ptr, end)<=0)
		if (ptr[0]>=begin[0]&&ptr[0]<=end[0])	
		{
			fileList[temp]=fileList[i];
			temp++;
		}		
	}
	listCount =temp;
	sortIndex = ByName;
	return listCount;
}

//this is mad! I already defined an enum type global variable to 
//indicate what should by sorted, however, I was forced to pass a 
//string instead of an enum index which I need to use a loop to find out!!!
void PrintList(char* sortby)
{
	int i=0;
	int (*comp)(const void*, const void*);//comp function pointer
	for (i=0; i<3; i++)
	{
		if (!strcmp(sortby, sortedBy[i]))
		{
			comp = compFuns[i];
			break;
		}
	}
	
	qsort(fileList, listCount, sizeof(int), comp);
	printInfo();
}


int SelectDate(int date)
{
	int i, temp=0;
	for (i=0; i<listCount; i++)
	{
		if (gmtime(&fileInfo[fileList[i]].mdate)->tm_mday==date)
		{
			fileList[temp]=fileList[i];
			temp++;
		}
		
	}
	listCount = temp;
	sortIndex = ByDate;
	return listCount;
}



//the help for UNIX is so BAAAAAAAAAAD that they give a wrong example
//which won't work under gcc which doesn't allow modify const pointer!!!!
int compName(const void*first, const void*second)
{
	//int* pi = first, *pj = second;
	//int i = *pi;
	//int j = *pj;
	int i = *((int*)first);
	int j = *((int*)second);
	return strcmp(fileInfo[i].name, fileInfo[j].name);

}


//this is the bug place
int compDate(const void*first, const void*second)
{
	int tempi = *((int*)first);  //is it strange?
	int tempj = *((int*)second);//is it strange?
	long i=fileInfo[tempi].mdate;
	long j=fileInfo[tempj].mdate;

	if ( i< j)
	{
		return -1;
	}
	else
	{
		if (i>j)
		{
			return 1;
		}
		else
		{
			return 0;
		}
	}
}

int compSize(const void*first, const void*second)
{
	int pi = *((int*)first);
	int pj = *((int*)second);
	
	int i=fileInfo[pi].size;
	int j=fileInfo[pj].size;
	
	if ( i< j)
	{
		return -1;
	}
	else
	{
		if (i>j)
		{
			return 1;
		}
		else
		{
			return 0;
		}
	}
}