NameFS Follow up, Sun Studio 11 — Pt. 4

I learned something cool about NameFS today..
You can mount a file descriptor to a folder and that entire folder’s contents are irretrievable. The folder becomes what I like to think as a symbolic link to the file descriptor. Isn’t that cool :D Furthermore the NameFS mounts can be done “invisibly” to the mntab, which is the automatic behaviour of fattach. Although, fattach does check that the file descriptor is a STREAM or door, I already showed in a previous part how that can be circumvented easily, by writing my own fattach() without the checks.
OK Here’s an example of the NameFS behaviour I was talking about..

bazz@life[pts/5][/tmp] mkdir /tmp/namefs
bazz@life[pts/5][/tmp] cd namefs
/tmp/namefs
bazz@life[pts/5][/tmp/namefs] touch 1 2 files
bazz@life[pts/5][/tmp/namefs] mkdir dir
bazz@life[pts/5][/tmp/namefs] touch dir/morefiles
bazz@life[pts/5][/tmp/namefs] ls
1      2      dir    files
bazz@life[pts/5][/tmp/namefs] ls -l
total 8
-rw-r--r--   1 bazz            0 Oct 29 19:56 1
-rw-r--r--   1 bazz            0 Oct 29 19:56 2
drwxr-xr-x   2 bazz          183 Oct 29 19:56 dir
-rw-r--r--   1 bazz            0 Oct 29 19:56 files
bazz@life[pts/5][/tmp/namefs] cd ..
bazz@life[pts/5][/tmp] ls -l | grep namefs
drwxr-xr-x   3 bazz          355 Oct 29 19:56 namefs
bazz@life[pts/5][/tmp] ~/namefs/a.out &
sizeof = 4
1st mount  = 0
2nd mount  = 0
[1] 7930

[1]+  Stopped                 ~/namefs/a.out
bazz@life[pts/5][/tmp] ls -l | grep namefs
-rwxr-xr-x   1 bazz            0 Oct 29 19:56 namefs
bazz@life[pts/5][/tmp] cd /tmp/namefs
-bash: cd: /tmp/namefs: Not a directory
bazz@life[pts/5][/tmp] echo "DERP" > /tmp/namefs
bazz@life[pts/5][/tmp] cd /tmp/namefs
-bash: cd: /tmp/namefs: Not a directory
bazz@life[pts/5][/tmp] fg
~/namefs/a.out

bazz@life[pts/5][/tmp] ls -l | grep namefs
drwxr-xr-x   3 bazz          355 Oct 29 19:56 namefs
bazz@life[pts/5][/tmp] cd namefs
/tmp/namefs
bazz@life[pts/5][/tmp/namefs] ls -l
total 16
-rw-r--r--   1 bazz            0 Oct 29 19:56 1
-rw-r--r--   1 bazz            5 Oct 29 19:57 2
drwxr-xr-x   2 bazz          183 Oct 29 19:56 dir
-rw-r--r--   1 bazz            0 Oct 29 19:56 files
bazz@life[pts/5][/tmp/namefs] cat 2
DERP
bazz@life[pts/5][/tmp/namefs]

and here’s the C code to a.out

/* By BAzz

This code bypasses the "Only STREAMS and doors allowed to be mounted"
as NameFS nodes thing. Kind of creates invisible symlinks :) 

*/


#include <sys/types.h>
#include <errno.h>
#include <stdio.h>
#include <stropts.h>
#include <sys/vnode.h>
#include <sys/door.h>
#include <sys/fs/namenode.h>
#include <sys/mount.h>
#include <fcntl.h>



int myfattach(int fildes, const char *path)
{
  struct namefd  namefdp;

  namefdp.fd = fildes;
  return (mount((char *)NULL, path,MS_OVERLAY|MS_DATA,
                    (const char *)"namefs", (char *)&namefdp,
                    4));
}

main()
{
  int fd1, fd2,fd3;
  char buf[100],buf2[100];
  char path1[] = "/tmp/namefs/1";
  char path2[] = "/tmp/namefs/2";
  char path3[] = "/tmp/namefs";
  int fd[201];
  
  int s;

  fd1 = open (path1, O_RDWR|O_CREAT );
  fd2 = open (path2, O_RDWR|O_CREAT );
  

  printf ("sizeof = %d\n", sizeof (struct namefd));
  
  int r = myfattach(fd1, path2);
  
  printf ("1st mount  = %d\n", r);
  if (r < 0) perror("");

  r = myfattach(fd2,path3);


  printf ("2nd mount  = %d\n", r);
  if (r < 0) perror("");

  getchar();

  umount(path3);
  umount(path2);

  close (fd1); close(fd2);
}

Sun Studio 11
I hear this is the last version supported by Solaris 8.
Well this can be found at http://ftp.cc.uoc.gr/programming/compilers/Sun/. I wanted this to compile a dynamic kernel module. Installing this thing required a j2se update from oracle’s website. And maybe u can bypass that by modifying the installer script to do a -nodisplay argument… Anyways.