Thread: Getting a file list from a hard disk?

Hi all,

I need to scan the contents of a hard drive on a computer and return the list of files on that drive. I'm able to scan the first level of hierarchy for a given drive letter, and am using a fairly primitive means of determining which is a folder and which is a file (presence of a period) and it works for most things, although will need to be changed later. However, I'm going to need to traverse the entire hierarchy and I'm a little unsure as to how I'm supposed to do it.

Can anyone provide any hints/pointers on how to approach this?

Thanks.

You need to mention your OS.

Cprogramming.com FAQ > Accessing a directory and all the files within it

Code:

system("dir *.* /s >all_files.txt") ;

Or, are you wanting to do this yourself and reinvent the wheel?

What you need to do is implement a recursive "find" function, that will recursively traverse the directory structure, this is the fastest way I know of finding every file in a filesystem structure

Here is some example code I wrote that executes a supplied function on every file within a supplied path including all sub-directories, ie so you could give it the root path / to get all files in the filesystem....

This example is for a Linux machine using the dirent structure:

Code:

/* These are the macros being used in the function below */
#define ff_get_dname(d) ((d)->d_name)  /* just change it once here :) if needbe */
#define ff_fmt_str(p) (*((p)+strlen((p))-1)=='/'?"%s%s":"%s/%s")     
#define ff_overhead 2 /* \0 and possible / so we add 2 to the string buffer */

Code:

int find_path(int (*exec)(const char *), const char * path)
{
  DIR * dptr;                  /* directory pointer */
  register struct dirent * cur_dirent;  /* current entry in directory */
  struct stat sb;              /* information about entry, type etc.. */
  register char * pathbuf;              /* string buffer for constructing filepath */
  register char * p;                    /* working pointer */
  size_t allocsiz;             /* holds size to currently allocate */

  if (!(dptr = opendir(path)))
    return 1;

  while (cur_dirent = readdir(dptr)) { /* intentional = */
    allocsiz = strlen(path)+strlen(ff_get_dname(cur_dirent))+ff_overhead;;
    if (!(pathbuf = malloc(allocsiz)))
      continue; /* skip file, couldn't get that much memory */
    sprintf(pathbuf,ff_fmt_str(path),path,ff_get_dname(cur_dirent));

    if (lstat(pathbuf,&sb) < 0) {
      free(pathbuf); /* free up our buffer */
      continue; /* failed to stat, skip */
    }

    if (S_ISDIR(sb.st_mode)) {
      p = ff_get_dname(cur_dirent);
      while (*p == '.') /* skip . or .. or ...etc.. */
        p++;
      if (*p)
        find_path(exec,pathbuf);
    }
    if (S_ISREG(sb.st_mode)) /* regular file */
      (void) exec(pathbuf); /* postive value indicates some sort of error occured */

    free(pathbuf); /* free our string buffer */
  }

  closedir(dptr);
  return 0;
}

Some declarations might be left out but you get the idea