[ProgClub list] Memory management in C

John Elliot jj5 at progclub.org
Sat Oct 1 09:44:46 AEST 2011


On 1/10/2011 8:56 AM, jedd wrote:
>   Bit of a cross (thread) posting .. soz.
>
>   I was going to observe that K&R is all you really need, since you're
>   a Real Programmer .. but then pondered on the fact that's all I
>   used when I was at college, and twenty years later I can barely
>   remember any C at all.  I recall that I really had a good handle on
>   pointers, and vaguely recall being chuffed (at the time) with this.

It's easy to be self-congratulatory when you get a handle on things that 
everyone says are hard. The thing is, pointers aren't hard!

>   Having said that - I'd expect that K&R would in fact give you about
>   90% of what you need to know .. until you get into the second stage
>   (analysing other people's code).

90% of what who needs to know for what? I haven't followed you man.

I think that K&R C is the term they use to describe the version of C 
before it got standardised by ANSI. So there's K&R C (the older version 
of C) and the new(er) ANSI C. AIUI K&R C has some anachronisms such as 
the way function parameter types are defined.

>   For your daemon project .. are you sure netcat can't do what you
>   want?

Haven't heard of netcat... one moment please... ah:

  http://netcat.sourceforge.net/

I'm not sure how that would help me. For the administration daemon..? 
The admin daemon listens on a port for commands and then executes them 
as a privileged user. Can netcat do that?

>   upstart (apt-cache show it) might be a good way of maintaining
>   its presence.

I think I'm just going to use the built in 'init' feature. Why wouldn't 
I use init and its 'respawn' facility?

>   And I echo the earlier observation - run it as a dedicated, non-root
>   user, mosdef.  This introduces two things that are going to prolong
>   the development process - learning how to drop privs, and working out
>   what uid/gid you should be using so you don't step on toes, present
>   and future, in the Debian world.

Yeah, that's cool. I'll setup a pcad user and add it to the sudo group, 
which will give it the permission it needs to read the particular files 
I need it to (i.e. the file that contains the password for the MySQL 
root user). Still, don't you need to supply your password when you 
invoke sudo? I didn't want to create a user that had to know its password.

I have a section on allocating user IDs in the administrative reference:

http://www.progclub.org/wiki/Administrative_reference#Allocating_user_IDs

Basically user accounts start at 1000, and utility accounts start at 
500. That should keep out of the way of the Debian standard users/groups 
shouldn't it?



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