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digitalmars.D.learn - Infinite loop not working DMD2

reply Guillermo Estrada <phrzn live.com> writes:
Hi, been developing in D a lot but first time in news groups, I
thought this might be the place.

I'm trying to make a fork bomb in D (of course no fork cause target
its windows platform) but anyway. I did one a while ago using D1 and
Tango and all ran perfectly, I'm trying to migrate my whole dev to
D2 and Phobos (reading Andrei's book) but this one does not work.

import std.process;

void main(string[] args) {
	while( true ) {
		execv(args[0], null);
	}
}

It spawns one after the other but just once, it always exits the
father process, if u comment the execv line, program stays in the
infinite loop as expected. any insight?
Jun 02 2011
next sibling parent reply Brad Roberts <braddr puremagic.com> writes:
On 6/2/2011 8:43 AM, Guillermo Estrada wrote:

 Hi, been developing in D a lot but first time in news groups, I
 thought this might be the place.
 
 I'm trying to make a fork bomb in D (of course no fork cause target
 its windows platform) but anyway. I did one a while ago using D1 and
 Tango and all ran perfectly, I'm trying to migrate my whole dev to
 D2 and Phobos (reading Andrei's book) but this one does not work.
 
 import std.process;
 
 void main(string[] args) {
 	while( true ) {
 		execv(args[0], null);
 	}
 }
 
 It spawns one after the other but just once, it always exits the
 father process, if u comment the execv line, program stays in the
 infinite loop as expected. any insight?


The exec* family of functions cause the new app to replace the current process.
 So after the execv, the loop doesn't exist.
Jun 02 2011
parent reply Guillermo Estrada <phrzn live.com> writes:
 The exec* family of functions cause the new app to replace the


current process.  So after the execv, the loop doesn't exist.

Any way to spawn the process without killing himself?
Jun 02 2011
parent reply =?UTF-8?B?QWxpIMOHZWhyZWxp?= <acehreli yahoo.com> writes:
On 06/02/2011 08:51 AM, Guillermo Estrada wrote:

 The exec* family of functions cause the new app to replace the


 current process.  So after the execv, the loop doesn't exist.

 Any way to spawn the process without killing himself?


Would std.process.system or std.process.shell work?

Ali
Jun 02 2011
next sibling parent reply Guillermo Estrada <phrzn live.com> writes:
== Quote from Ali Çehreli (acehreli yahoo.com)'s article

 On 06/02/2011 08:51 AM, Guillermo Estrada wrote:

 The exec* family of functions cause the new app to replace the


 current process.  So after the execv, the loop doesn't exist.

 Any way to spawn the process without killing himself?


 Would std.process.system or std.process.shell work?
 Ali


Well, std.process.system does not wok as intended because if you
kill the parent process all children die. std.process.shell works
and does what it should but spawning a cmd on each request, for a
dirty quick fork bomb well, it's the same, but there should be a way
in phobos to spawn process and detach them or even have control over
them and close them like in tango.sys.Process, without having to go
to the std.c.* libs. Thnx for the help :D
Jun 02 2011
parent reply Jonathan M Davis <jmdavisProg gmx.com> writes:
On 2011-06-02 09:14, Guillermo Estrada wrote:

 =3D=3D Quote from Ali =C7ehreli (acehreli yahoo.com)'s article
=20

 On 06/02/2011 08:51 AM, Guillermo Estrada wrote:

 The exec* family of functions cause the new app to replace the


=20
 current process.  So after the execv, the loop doesn't exist.
=20
 Any way to spawn the process without killing himself?


=20
 Would std.process.system or std.process.shell work?
 Ali


=20
 Well, std.process.system does not wok as intended because if you
 kill the parent process all children die. std.process.shell works
 and does what it should but spawning a cmd on each request, for a
 dirty quick fork bomb well, it's the same, but there should be a way
 in phobos to spawn process and detach them or even have control over
 them and close them like in tango.sys.Process, without having to go
 to the std.c.* libs. Thnx for the help :D


Okay. I just glanced at std.process, and I'd suggest trying spawnvp. It loo=
ks=20
like it ends up calling fork, so it'll probably work. I haven't tried it=20
though and don't know anything about the function beyond what's in the code.

Also, just because there _should_ be a way for there to do something in=20
druntime or Phobos doesn't mean that there _is_ a way. There's plenty that =
you=20
still have to call C functions for, if nothing else because it takes time t=
o=20
add all of the relevant features, and not all of the relevant features are=
=20
always remembered by the Phobos developers. So, if you can't find something=
=20
that really seems like it should be in Phobos, open an enhancement request =
on=20
it on bugzilla: d.puremagic.com/issues/

=2D Jonathan M Davis
Jun 02 2011
parent reply Guillermo Estrada <phrzn live.com> writes:
== Quote from Jonathan M Davis (jmdavisProg gmx.com)'s article

 On 2011-06-02 09:14, Guillermo Estrada wrote:

 == Quote from Ali Çehreli (acehreli yahoo.com)'s article


 On 06/02/2011 08:51 AM, Guillermo Estrada wrote:

 The exec* family of functions cause the new app to replace










the

 current process.  So after the execv, the loop doesn't








exist.

 Any way to spawn the process without killing himself?


 Would std.process.system or std.process.shell work?
 Ali


 Well, std.process.system does not wok as intended because if you
 kill the parent process all children die. std.process.shell




works

 and does what it should but spawning a cmd on each request, for




a

 dirty quick fork bomb well, it's the same, but there should be a




way

 in phobos to spawn process and detach them or even have control




over

 them and close them like in tango.sys.Process, without having to




go

 to the std.c.* libs. Thnx for the help :D


 Okay. I just glanced at std.process, and I'd suggest trying


spawnvp. It loo

 ks
 like it ends up calling fork, so it'll probably work. I haven't


tried it

 though and don't know anything about the function beyond what's in


the code.

 Also, just because there _should_ be a way for there to do


something in

 druntime or Phobos doesn't mean that there _is_ a way. There's


plenty that

 you
 still have to call C functions for, if nothing else because it


takes time t

 o
 add all of the relevant features, and not all of the relevant


features are

 always remembered by the Phobos developers. So, if you can't find


something

 that really seems like it should be in Phobos, open an enhancement


request

 on
 it on bugzilla: d.puremagic.com/issues/
 - Jonathan M Davis


Johnathan, just yesterday I was at github checking exactly the same
thing, spawnvp() is not documented and still on development, but it
seems it just call the underlying std.c.process.spawnvp function,
either way, spawnvp in either P_NOWAIT or P_NOWAITO modes will spawn
child process... so killing the father is the case of calling
system(args[]) but I'll have to test it. Thnx for the ideas.
Jun 02 2011
parent Guillermo Estrada <phrzn lve.com> writes:
 So, if you can't find something that really seems like it should
 be in Phobos, open an enhancement request on it on bugzilla:
 d.puremagic.com/issues/
 Jonathan M Davis


As expected spawnvp() creates child process that exit with the father,
just as system(). exec*() replaces the parent process, the only one I
can use is shell() that actually opens a cmd with the process
(detached) and expects the output, so in any other use shell() is not
a viable option. Gonna keep trying, and I will create an enhacement
request as you propose, Thnx.
Jun 02 2011
prev sibling parent Jonathan M Davis <jmdavisProg gmx.com> writes:
On 2011-06-02 08:59, Ali =C7ehreli wrote:

 On 06/02/2011 08:51 AM, Guillermo Estrada wrote:

 The exec* family of functions cause the new app to replace the


=20
 current process.  So after the execv, the loop doesn't exist.
=20
 Any way to spawn the process without killing himself?


=20
 Would std.process.system or std.process.shell work?


If they were called in spawned threads. What he really wants is fork though=
, I=20
believe (it _is_ a _fork_ bomb after all), but I'm not sure how safe that i=
s=20
or isn't to call in D, since I don't know how that affects the state of the=
=20
druntime. It's probably okay, since you then have two, completely separate=
=20
processes, but I don't know. Regardless, you'd have to be calling the C for=
k,=20
because I don't believe that druntime or Phobos provide any kind of wrapper=
=20
for fork.

=2D Jonathan M Davis
Jun 02 2011
prev sibling parent reply "Steven Schveighoffer" <schveiguy yahoo.com> writes:
On Thu, 02 Jun 2011 11:43:50 -0400, Guillermo Estrada <phrzn live.com>  
wrote:


 Hi, been developing in D a lot but first time in news groups, I
 thought this might be the place.

 I'm trying to make a fork bomb in D (of course no fork cause target
 its windows platform) but anyway. I did one a while ago using D1 and
 Tango and all ran perfectly, I'm trying to migrate my whole dev to
 D2 and Phobos (reading Andrei's book) but this one does not work.

 import std.process;

 void main(string[] args) {
 	while( true ) {
 		execv(args[0], null);
 	}
 }

 It spawns one after the other but just once, it always exits the
 father process, if u comment the execv line, program stays in the
 infinite loop as expected. any insight?


std.process is woefully unmaintained.  Lars K is developing a new version,  
and I am really really late getting a windows version to him so it can be  
included in phobos.  It includes simple methods to create a sub-process,  
which should solve your issue.

I think this shall be my next "Spare time" project for D.  Sorry about  
this, Lars.

-Steve
Jun 02 2011
parent Guillermo Estrada <phrzn live.com> writes:
 std.process is woefully unmaintained.  Lars K is developing a new


version,

 and I am really really late getting a windows version to him so it


can be

 included in phobos.  It includes simple methods to create a sub-


process,

 which should solve your issue.
 I think this shall be my next "Spare time" project for D.  Sorry


about

 this, Lars.
 -Steve


Well Steve I hope to see it soon, I love D and I just hope GSoC
helps it a LOT, for me I'm just going to make some updated bindings
to work with D2 now that I'm migrating to it.
Thnx for the reply.
Jun 02 2011