[PATCH] 2nd attempt at deluser/delgroup size reduction and improvements

Tito farmatito at tiscali.it
Tue Oct 5 20:38:14 UTC 2010


On Monday 04 October 2010 08:10:11 Tito wrote:
> On Monday 04 October 2010 00:45:30 you wrote:
> > On Sunday 03 October 2010 21:18, Tito wrote:
> > > Hi,
> > > this patch partially reduces size of deluser/delgroup and adds better
> > > error checking and a few additional features:
> > > 
> > > Pros:
> > > 1) size increase vs functionality is not bad. With all options enabled:
> > > 
> > > scripts/bloat-o-meter busybox_old busybox_unstripped
> > > function                                             old     new   delta
> > > deluser_main                                         189     214     +25
> > > .rodata                                           134994  135016     +22
> > > ------------------------------------------------------------------------------
> > > (add/remove: 0/0 grow/shrink: 2/0 up/down: 47/0)               Total: 47 bytes
> > > 
> > > 2) proper error checking and reporting if removing non existent user/group
> > > 3) proper error checking and reporting if removing primary group of a user
> > > 4) deluser also removes user's primary group if ENABLE_DELGROUP is set, so no leftovers
> > 
> > Why? Who said that group foo needs to be removed when user foo is being removed?
> > Do other deluser utilities do this?
> Hi
> Yes at least on my Debian system if i create a user:
> 
> adduser prova
> Adding user `prova' ...
> Adding new group `prova' (1006) ...
> Adding new user `prova' (1004) with group `prova' ...
> The home directory `/home/prova' already exists.  Not copying from `/etc/skel'.
> Enter new UNIX password:
> Retype new UNIX password:
> passwd: password updated successfully
> Changing the user information for prova
> Enter the new value, or press ENTER for the default
>         Full Name []:
>         Room Number []:
>         Work Phone []:
>         Home Phone []:
>         Other []:
> Is the information correct? [Y/n] debian:/home/tito/Desktop#
> 
> 
> grep prova /etc/pashadowetc/shadow /etc/group /etc/gshadow
> /etc/passwd:prova:x:1004:1006:,,,:/home/prova:/bin/bash
> /etc/shadow:prova:$6$I..Q9V.z$aoa7lBKlI68heRLDh9E0oMm8DUiBFO9MfBZgOYYjr/09v0Z1nPipjDPxz7TbbuwLmRslWZVdpI3Wr/G4IxDrl1:14886:0:99999:7:::
> /etc/group:prova:x:1006:
> /etc/gshadow:prova:!::
> 
> deluser prova
> Removing user `prova' ...
> Warning: group `prova' has no more members.
> Done.
> grep prova /etc/passwd /etc/shadow /etc/group /etc/gshadow
> debian:/home/tito/Desktop#                                
> 
> 
> adduser command creates a group with the same name as the username,
> and makes this group the primary group for that user. This is called a user private group (UPG)
> 
> So i test if a group with the same name exists and delete it,
> Maybe a check if the group is empty could be added but as
> we don't check for that at all in the current implementation
> and happily remove non-empty groups I've skipped that.
> 
> > 
> > > 5) maximum dead code optimization by the compiler with different options turned off
> > > 
> > > Contra:
> > > 1) code is obfuscated, sorry can't do nothing about that it's my style.
> > > 2) Not known ....yet :-)
> > > 
> > > The patch is tested and seems to work well for me.
> > > More testing by the list members is appreciated.
> > > Hints, critics and improvements by the list members are welcome.
> > > Please apply if you like it.
> > 
> > +				if (!member && getpwnam(name))
> > +					bb_error_msg_and_die("is %s's primary group", name);
> > 
> > This looks unreadable. Can be rewritten to do the same,
> > but make more sense to human reader, as:
> > 
> > 	if (!member) {
> > 		if (getpwnam(name) = 0) {
> > 			bb_error_msg_and_die("is %s's primary group", name);
> > 		}
> > 	}
> > 
> 
> Can change it if you like it that way, for my personal taste just  3 wasted lines :-)
> 
> Should be:
> 
>  	if (!member) {
>  		if (getpwnam(name)) {
>  			bb_error_msg_and_die("is %s's primary group", name);
>  		}
>  	}
> 
> We check if getpwnam returns a struct passwd and in this case
> it is a primary group (group with the same name of a user).
> 
> > The message also needs to be better. This:
> > 
> > deluser: is foo's primary group: <strerror here>
> > 
> > is incomprehensible. What are you trying to say?
> > 
> 
> Original error message on my system is:
> 
> delgroup tito
> /usr/sbin/delgroup: `tito' still has `tito' as their primary group!
> 
> I shortened it a little to:
> 
> delgroup: is tito's primary group 
> 
> Could be changed. As i'm not a native english speaker I'm open
> to suggestions about a short and easy to understand error message
> for this use case.
> 
> 
> Ciao,
> Tito
> 

Here v4,

just cosmetical changes for readability.

Ciao,
Tito
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