implementing a call to output disk space for sftp

eugenewg · 01-06-2005, 10:07 PM

Hi all,
Note, this is regarding OpenBSD.
I've been trying to figure out how to output to a client sftp user the current disk space and total disk space (other other useful information for that matter) each time a user uploads/deletes/creates file/folders etc. I've made numerous posts on different forums/mailing lists and no one seemed to be able to answer my question. So, I decided to e-mail Theo which e-mailed me back suprisingly in 2 mins flat, and wrote the following:

'There is nothing to do what you want. You'll have to do it by hand.'

So, now, I'm here. I have absolutely no idea where to start with this, learning a new language is not a problem. I already know a decent amount of C++, but it seems that all the books that are listed on the OpenBSD website are all regarding C.
Thank you for your help in advance.

Eugene

jwstric2 · 01-07-2005, 01:46 PM

considering if you have the sftp source code you will need to insert some code to send a message displaying the disk space. THe disk space code is pretty simple.

first :

man statfs , this is a good start place

Code:

/*Find mount point for a particular directory*/
static char *
find_mount_point (const char *file)
{
  char saved_cwd[MAXFILEPATH];
  static char mp[MAXFILEPATH];
  struct stat last_stat;

  getcwd (saved_cwd, MAXFILEPATH);

  if (chdir (file) < 0){
    return NULL;
  }
  
  if (stat (".", &last_stat) < 0){
    goto done;
  }

  /* Now walk up FILE's parents until we find another filesystem or /,
     chdiring as we go.  LAST_STAT holds stat information for the last place
     we visited.  */
  for (;;)
    {
      struct stat st;
      if (stat ("..", &st) < 0)
  goto done;
      if (st.st_dev != last_stat.st_dev || st.st_ino == last_stat.st_ino)
  /* cwd is the mount point.  */
  break;
      if (chdir ("..") < 0)
  goto done;
      last_stat = st;
    }

  /* Finally reached a mount point, see what it's called.  */
  getcwd (mp, MAXFILEPATH);

done:
  /* Restore the original cwd.  */
  {
    int save_errno = errno;
    chdir(saved_cwd);
    errno = save_errno;
  }

  return mp;
}

Code:

/*Find statitics of mount*/
static void refreshMount(char *mount){
  struct statfs s;
  long long usedSize;
  long long freeSize;

  if (statfs(mount, &s) != 0) {    
    return;
  }
   
  usedSize = (long long)((((long long)s.f_blocks) - s.f_bfree)* s.f_bsize);
  freeSize = (long long)(((long long)s.f_bavail) * s.f_bsize);      
  
}

I had to rip some of my code out but this should work for you. Give it a whirl.

eugenewg · 01-09-2005, 08:38 PM

Thank you so much for you help jwstric2. I was wondering which books would you suggest to read in order to learn C, and integrate it with the operating system?
Thank you,

Eugene

jwstric2 · 01-09-2005, 09:10 PM

Well I never really read a book but one of the bests I've been told is one of the oldest, The C Programming Language by Brian W Kernighan. So some googling searching though and get a grasp of how memory is laid out, how memory allocation works, ect.. I think once I understood most of the underlying concepts of the system, it make programming in any language much more simple.

Good luck

eugenewg · 01-09-2005, 09:13 PM

Thanks again, I have already ordered that book from previous googling.

Eugene

bigearsbilly · 01-10-2005, 04:44 AM

This is the book you need... (ask anyone)

http://www.amazon.com/gp/reader/0201...21#reader-link