[Toodd]

I'm trying to make a program that reproduces the command line ls and -l to see the files that are in a directory.

Arguments of function main are:

ls [-l] [directory]

where [...] symbolizes that the argument is opcional.

The output for every file of the folder when -l is one of the arguments should be:

size_in_bytes month day hours:minutes name

For example: 273635 Nov 16 09:34 file.ext

Otherwise the output is simply the name of each file.



This is the message I got when running the program after successful compilation:

Symbol lookup error: undefined symbol: localtime, version GLIBC_2.2.5

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

int main(int argc, char **argv)
   {

   int l_activated = 0;
   struct dirent *info;
   struct stat *more_info;
   struct tm *data;
   char folder[100],file[100], time[50], cwd[1024];

   DIR *diretory;

   getcwd(cwd,sizeof cwd);


   if (argv[2]==NULL)
      strcpy(folder,cwd);
   else if (strcmp (argv[2],"-l")==0)
     {
      l_activated = 1;

      if (argv[3]== NULL)
         strcpy(folder,cwd);
      else 
        strcpy(folder,argv[3]);
     }
   else
     strcpy(folder,argv[2]);

   diretory = opendir(folder);
   
   info = readdir(diretory);
   
   while (info != NULL)
     {
     if (l_activated == 1)
        {
	  strcpy(file,folder);
	  strcat(file,"/");
	  strcat(file,info->d_name);	 

	  stat(file , more_info );
	  data = localtime(&more_info->st_mtime);
	  strftime (time, sizeof (time), "%b %e  %H:%M", data);

      	  printf("\n%10zd   %s  %s", more_info->st_size, time, info->d_name);
	}
     else
        printf("\n%s",info->d_name);
  
     info = readdir(diretory);
     }
   
   printf("\n\n");

   closedir(diretory);

   return 0;
   }

what does it means?

[Toodd]

Help please?

[dwise1_aol]

gcc on my Ubuntu (Kosmic Koala) throws a warning that more_info may be used uninitialized.

int main(int argc, char **argv)
   {

   int l_activated = 0;
   struct dirent *info;
   struct stat *more_info;
   struct tm *data;
   char folder[100],file[100], time[50], cwd[1024];

 . . .

	  strcpy(file,folder);
	  strcat(file,"/");
	  strcat(file,info->d_name);	 

	  stat(file , more_info );
	  data = localtime(&more_info->st_mtime);

The way that you're calling stat, it's as if you expect stat to have created a static struct somewhere that it's giving you the pointer to. However, when I read the man page for stat I didn't see any such statement. And when I looked it up in a textbook on Linux systems programming, they declared an actual stat struct and passed its address to stat. Besides, if stat were returning a pointer to a struct through the parameter list, then it would have to have been declared as struct stat **, not just struct stat *, and you would have had to have passed the address of more_info so that the function could change that pointer.

Instead, you should probably write that as:

int main(int argc, char **argv)
   {

   int l_activated = 0;
   struct dirent *info;
   struct stat more_info;
   struct tm *data;
   char folder[100],file[100], time[50], cwd[1024];

 . . .

	  strcpy(file,folder);
	  strcat(file,"/");
	  strcat(file,info->d_name);	 

	  stat(file , &more_info );
	  data = localtime(&more_info.st_mtime);

I haven't tested that.

Also, the man page says that not all the time fields are updated by some Linux file systems. Plus there are several things that could change the st_mtime field. You should probably review the man page of stat() yourself.