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Date: Sat, 30 Apr 2011 14:26:23 +0100
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Subject: Re: [PHP-DEV] adding low level file handling stuff
From: glopes@nebm.ist.utl.pt ("Gustavo Lopes")

On Sat, 30 Apr 2011 13:04:12 +0100, Ferenc Kovacs <tyra3l@gmail.com> wrote:

> recently I found a nice blogpost about how to properly daemonize a php
> daemon:
> http://andytson.com/blog/2010/05/daemonising-a-php-cli-script-on-a-posix-system/
> I've noticed in this article, that you can replace/redirect the
> STDIN/STDOUT/STDERR from inside of your script, you have to close them,  
> and open in the correct order.
> It works (at least on linux), because the opened files will have the  
> 1,2,3 FDs, because the OS assign the lowest available FD, which will  
> happen to be the required ones.
>
> [...]
> So to correctly address this, one would need a way to get the FD for a  
> given fp and to be able to explicitly set the FD for an fp.
> The required C methods for this would be the fileno and dup2.
>
> I've started to look around, that maybe there are existing
> functions/extensions to make this work.
> I've found that with 5.3.6 one can open arbitrary FDs thanks to Gustavo:
> http://bugs.php.net/bug.php?id=53465
> this is the equivalent of fdopen, which was requested by Dennis Hotson
> http://marc.info/?t=126854891300001&r=1&w=2 and he did implement that
> https://github.com/dhotson/fdopen-php  (+1 for adding fdopen also, the
> stream based solution isn't obvious and easy to spot)
>
> But this doesn't help this problem.
>
> [...]
> I would like to know, that why do these methods lacks (just nobody needed
> them, or maybe it was a decision to keep out such low level methods from  
> the core)?
> and if someone would make those, what should be the best place to add.
>
>  [...]

I actually did consider adding support for an extended form of php://fd  
where one would specify the desired file descriptor: php://fd/<orig  
fd>/<new fd>. It would call dup2 instead of dup.

However, I got into some trouble on shutdown because this could cause  
stdout to be closed ahead of time and then the output subsystem would  
cause either a segfault or a memory leak (can't recall). I didn't spend  
more than 20 minutes on this as it was not the problem I was trying to  
solve, so there's probably an easy solution. If you want to work on this,  
extending php://fd would likely be a good place.

-- 
Gustavo Lopes