9






     in	1970 UNIX was created as a small version of multiics
on  PDP-11 asm language, few years later it got	rewritten on
C. one of reasons of UNIX popularity was unified file system
view,  everything  was	on  files,  hence you could use	same
toolbox.  as time goes,	it gets	replaced by  the  fact	that
everyone  uses UNIX because everyone uses UNIX.	 and started
to port	alien programs,	using alien ways  and  alien  inter-
face.


     however, all UNIXes share these problems, even on	most
modern and advanced versions of	*nix-like systems:


*   UNIX was  a	 multiuser  system  for	 mainframes,  poorly
    ported to PC (i386 and amd64) platform and still doesn't
    fit.  and it will be worse on Risc-V/aarch64.


*   Research UNIX itself was about the showing all resources
    as	files,	this  is ignored by modern UNIX	as there are
    many examples for it.  (on graphics,  networking,  audio
    and	security)


*   networking on UNIX is most of time is done using sockets
    (BSD  and Linux) and STREAMS (SystemV) both	apply poorly
    to modern networking.


     No	version	of UNIX	was able to solve these	problems, as
all  UNIXes  are  trying  to do	something in different ways.
Plan9 however, doesn't try to be  a  UNIX.   it	 doesn	many
stuff  on  UNIX	 such as (sym, hard)links, sockets, X11, sh,
chroot,	NFS,  teletype	terminals,  sysctls,  daemons,	ssh,
dynamic	linked programs, /etc, dotfiles	and root.


     Instead of	all of those features on UNIX, Plan9  solves
problems with two key ideas:



*   9p:	a unified protocol for programs	to  create  do	file


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			   - 2 -


    operations,	 on  userland,	which  solves  many problems
    about files	and makes a unified UI.	which makes usage of
    everything is file possible	by the	whole system.



*   private namespaces:	which allows each process  has	it's
    own	 view  on  file	 system,  which	solves many problems
    about security and makes extending system without touch-
    ing	it possible.


     for example let's say you have your httpd and you	want
to  do	chroot on /var/www for httpd. on OpenBSD it would be
like:


1)  copy all files needed to run httpd to /var/www/

2)  chroot

3)  httpd


     if	you have ever bothered to it, you know how  hard  it
is  to	do.  thanks to magic of	dynamic	linked programs.  on
Plan9 it can be	done in	two ways:


1)  bind /var/www to /

2)  httpd


     This one will be more like	classic	chroot,	besides	that
there  is  no  dynamic	linked httpd to	annoy you it's same.
all sub-process	will see /var/www as / and there is  no	 way
to  escape  it,	all other procs	will work as expected.	how-
ever, the magic	will happen on other way:


1)  bind everything you	don't need to a	empty place.

2)  httpd


     This will be more like unveil, OpenBSD used it as	eas-
ier  way  for users to handle this problem.  the drawback of
unveil is it will need some serious hacking around the	pro-
gram, binds don't have this problem.


     another example: let's  say  you  don't  want  to	have
/secret-data folder to be visable by httpd.


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			   - 3 -


  % mkdir empty
  % bind empty/	/secret-data
  % httpd



     httpd will	never know what	is really  on  /secret-data,
it  just  will	see  whatever  is  on empty/ all other procs
(besides httpd forks), will see	/secret-data as	is.















































		     November 21, 2024