Re: Autoconf 2.52g is released

[Akim Demaille]

I hope you don't mind my using this text into the Autoconf doc?

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> Thomas> "cp -p" has some unfortunate side-effects (some versions copy
> Thomas> the ownership of the original file in addition to the
> Thomas> protection)
> 
> Do you have references for this?  This is typical information that
> must be double checked and included in autoconf.texi once certified.

The 'cp -p' command always -tries- to copy ownerships.  But whether it
actually does copy ownerships or not is a system dependent policy
decision implemented by the kernel.  If the kernel allows it then it
happens.  If the kernel does not allow it then it does not happen.  It
is not something the cp command itself has control over.

In SysV any user can chown files to any other user, and also had a
non-sticky /tmp.  That undoubtedly derives from the heritage of SysV
in a business environment without hostile users.  BSD changed this to
be a more secure model where only root can chown files, and used a
sticky /tmp.  That undoubtedly derives from the heritage of BSD in a
campus environment.

Linux by default follows BSD, but it can be configured to allow chown.
HP-UX as an alternate example follows SysV, but it can be configured
to use the modern security model and disallow chown.  That is how mine
are configured.  Since it is an administrator configurable parameter
you can't use the name of the kernel as an indicator of the behavior.

See the single unix specification for the standards information on
what cp -p should or should not do.

  http://www.unix-systems.org/single_unix_specification_v2/xcu/cp.html

See the GNU fileutils faq here for more details and rational on this
particular topic.  (Since I wrote it I recommend it.)

  
http://www.gnu.org/software/fileutils/doc/faq/core-utils-faq.html#Why%20can%20only%20root%20chown%20files%3f

Stevens "Advanced Programming in the UNIX Environment" section 4.10 &
4.11 has good information.

HTH

Bob