Package: fileutils
Version: 3.13-1
When running "chgrp" as root, no errors or warnings are given when the
group doesn't exist (e.g. when accidently using "chown"'s user.group
syntax), but the group is changed to a nearly unpredictable value.
Script started on Sat Aug 10 15:36:27 1996
zensunni root 15:36:28 ~/tmp # id
uid=0(root) gid=0(root) groups=0(root)
zensunni root 15:36:32 ~/tmp # touch demo
zensunni root 15:36:37 ~/tmp # ls -l demo
-rw-r--r-- 1 root root 0 Aug 10 15:36 demo
zensunni root 15:36:41 ~/tmp # chgrp an.error demo
zensunni root 15:36:54 ~/tmp # ls -l demo
-rw-r--r-- 1 root sys 0 Aug 10 15:36 demo
zensunni root 15:36:58 ~/tmp # chgrp --help
Usage: chgrp [OPTION]... GROUP FILE...
Change the group membership of each FILE to GROUP.
-c, --changes like verbose but report only when a change is made
-h, --no-dereference affect symbolic links instead of any referenced file
(available only on systems with lchown system call)
-f, --silent, --quiet suppress most error messages
-v, --verbose output a diagnostic for every file processed
-R, --recursive change files and directories recursively
--help display this help and exit
--version output version information and exit
zensunni root 15:37:06 ~/tmp # chgrp -c an.error demo
group of demo changed to an.error
zensunni root 15:37:26 ~/tmp # ls -l demo
-rw-r--r-- 1 root adm 0 Aug 10 15:36 demo
zensunni root 15:37:30 ~/tmp # chgrp -c -v an.error demo
group of demo changed to an.error
zensunni root 15:37:39 ~/tmp # ls -l demo
-rw-r--r-- 1 root tty 0 Aug 10 15:36 demo
zensunni root 15:37:42 ~/tmp # exit
Script done on Sat Aug 10 15:37:47 1996
Additional information:
- when running "chgrp" as an ordinary user and specifying a non-existant
group, an error message is likely to be given, e.g.
zensunni ray 15:41 /tmp> touch blech
zensunni ray 15:41 /tmp> chgrp blub blech
chgrp: you are not a member of group `blub': Operation not permitted
Exit 1
zensunni ray 15:41 /tmp> grep blub /etc/group
Exit 1
A better message would be: `blub': no such group, but at least an error
is given.
Educated guess of cause:
This is an upstream bug. chgrp's parse_group (chgrp.c:123) is designed
to handle numeric gids too. For this purpose, xstrtoul is called
(line 138) which returns 0 for OK, or an error value (defined in
lib/xstrol.h). Only one of the possible error values (LONGINT_OVERFLOW)
causes chgrp to exit with a fatal error.
This explains why the problem doesn't often manifest itself when
chgrp is run as an ordinary user: ordinary users are members of only
a few groups, and are not allowed to chgrp to a group that they are
not a member of, including numerical gids not in /etc/group. The
interpretation of the "group" argument as a numerical gid is unlikely to
be that of a group of which the user is a member.
Ray
--
Cyberspace, a final frontier. These are the voyages of my messages,
on a lightspeed mission to explore strange new systems and to boldly go
where no data has gone before.
