c program backdate

dilberim82 · 04-21-2004, 02:13 PM

I have a question about this program. This program is supposed to take the inode information modtime and atime of a file and modify it. I did not really think much about this code so there are some consistencies but its better than nothing. My code is:

Code:

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

main(int argc, char *argv[])
{
	DIR *dirp;
	struct dirent *dentry;
	struct stat buffer;
	struct utimbuf date;
	char* fname;
	int days;

	if(argc < 1 || argc > 3)
	{
		fprintf(stderr, "usage: backdate [path] filename days\n");
		exit(1);
	}
      if(argc == 2)
		{
		fname = argv[1];
		days = argv[2];
		}
		else
		{
			if(chdir(argv[1]) == NULL)
				{
				fprintf(stderr, "%s: cannot open %s\n", argv[0], argv[1]);
				exit(1);
				}
			else
			{
			fname = argv[2];
			days = argv[3];
			}
		}

	while((dentry = readdir(chdir(argv[1]))) != NULL)
	{
		if(strcmp(dentry->d_name, fname) == 0)
			break;
		else if(dentry == NULL)
		{
			printf("%s does not exist \n", fname);
			exit(0);
		}
	}
	date.actime = buffer.st_atime-(days*60*60*24);
	date.modtime = buffer.st_mtime-(days*60*60*24);
	printf("Inode has been modified\n");
}

When i compile it, it gives me the errors:

backdate.c:54: request for member `actime' in something not a structure or union
backdate.c:55: request for member `modtime' in something not a structure or union

whats that mean? and how do i fix it?

dilberim82 · 04-21-2004, 03:16 PM

Is there a good debugging tool for unix? When i run this program it keeps giving me the same error. What the heck is "segmantation fault"?

Hko · 04-21-2004, 05:05 PM

Quote:

Is there a good debugging tool for unix?

Yes: gdb
Best run from within emacs IMHO.
(M-x gdb)

Hko · 04-21-2004, 05:15 PM

Quote:

Originally posted by dilberim82
What the heck is "segmantation fault"?

A severe programming error, i.e. referencing some pointer that points to memory not assigned (allocated / declared) for your program.

Hko · 04-21-2004, 05:25 PM

Code:

#include <sys/types.h>
#include <sys/stat.h>
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <dirent.h>
#include <time.h>
#include <utime.h>  /* FIXED: You forgot this one */

int main(int argc, char *argv[])   /* FIXED: forgot return type, not important though. */
{
	 DIR *dirp;
	 struct dirent *dentry;
	 struct stat buffer;
	 struct utimbuf date;
	 char* fname;
	 int days;

	 if(argc < 1 || argc > 3) {
		  fprintf(stderr, "usage: backdate [path] filename days\n");
		  exit(1);
	 }
	 if(argc == 2) {
		  fname = argv[1];
		  days = atoi(argv[2]);  /* FIXED: need to convert string to int */
	 } else {
		  if(chdir(argv[1]) < 0) {  /* FIXED: chdir returns int not pointer */
			   fprintf(stderr, "%s: cannot open %s\n", argv[0], argv[1]);
			   exit(1);
		  } else {
			   fname = argv[2];
			   days = atoi(argv[3]);  /* FIXED: need to convert string to int */
		  }
	 }

	 while((dentry = readdir(chdir(argv[1]))) != NULL) {  

         /* After checking the line above I gave up.  Doesn't make sense.
            Please read the man pages on the functions you call
	    and try to fix at least some things yourself first.			
	 */

dilberim82 · 04-21-2004, 10:23 PM

Code:

#include <sys/types.h>
#include <sys/stat.h>
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <dirent.h>
#include <time.h>
#include <utime.h>  /* FIXED: You forgot this one */

int main(int argc, char *argv[])   /* FIXED: forgot return type, not important though. */
{
	 DIR* dp;
	 struct dirent *dentry;
	 struct stat buffer;
	 struct utimbuf date;
	 char fname[50];
	 int days, time1, time2;

	 if(argc < 3 || argc > 4) {
		  fprintf(stderr, "usage: backdate [path] filename days\n");
		  exit(1);
	 }
	 if(argc == 3) {
		  dp = opendir(".");
		  strcpy(fname, argv[1]);
		  days = atoi(argv[2]);  /* FIXED: need to convert string to int */
		  printf("Days in 4 args is: %d\t%s\n", days*60*60*24, fname);
	 } else {
		  dp = opendir(argv[1]);
		  if(dp == NULL) {  /* FIXED: chdir returns int not pointer */
			   fprintf(stderr, "%s: cannot open %s\n", argv[0], argv[1]);
			   exit(1);
		  } else {
			   strcpy(fname, argv[2]);
			   days = atoi(argv[3]);  /* FIXED: need to convert string to int */
		  printf("Days in 4 args is: %d\t%s\n", days*60*60*24, fname);
		  }
	 }

	while((dentry = readdir(dp)) != NULL)
	{

	  if(strcmp(dentry->d_name, fname) == 0)
	  {
      printf("file is in the directory");
      break;
      }
	}
		if(dentry == NULL)
		{
		printf("could not find %s \n", fname);
		exit(0);
		}
	if(stat(fname, &buffer) == -1){
		fprintf(stderr, "incorrect stat access\n");
		exit(1);
	}

	    date.actime = buffer.st_atime - (days*60*60*24);
		date.modtime = buffer.st_mtime - (days*60*60*24);

		printf("Inode has been modified\n");

closedir(dp);
return(0);
}

First, thank you for the replies Hko. I think this fixed most of the errors but i still didn't get the result i want. What am i doing wrong?

dilberim82 · 04-21-2004, 10:31 PM

well on a second look, it does modify the date.actime and date.modtime but when i do an ls, it does not show up there. am i missing something here?