Re: Error build -STABLE ports on bento

On Fri, 16 Jan 2004, Joe Marcus Clarke wrote:

> On Fri, 2004-01-16 at 02:44, Joe Marcus Clarke wrote:
> > I'm trying to get the latest 4-exp build done, and I'm seeing a strange
> > problem.  The -STABLE chroots (running 490101) built under FreeBSD
> > -CURRENT (501114) refuse to copy 0 length files.  Whenever cp encounters
> > a 0 length file, it fails with EINVAL.  For example:
> >
> > cp: /tmp/a/ports/sysutils/usermin/work/usermin-1.051/install-type:
> > Invalid argument
> >
> > This is not happening with the same -STABLE version built and run under
> > FreeBSD -CURRENT 501108.  Non-zero length files are copied just fine.
> > Is this something I should expect to be fixed if the cluster is upgraded
> > to today's -CURRENT?  Is there a simple workaround that can be used in
> > lieu of upgrading at this time?  Thanks.
>
> Hmmm...sorry to follow up to myself, but I just tested the same -STABLE
> under a -CURRENT 502101 machine, and the behavior is the same.  cp
> returns EINVAL when trying to copy zero-length files.

munmap(2) was recently perfectly broken to POSIX spec so that it doesn't
work on zero-length files.  cp and probably other utilities in RELENG_4
and older versions of FreeBSD are missing the fix for this, so they
can't work right under -current.

% RCS file: /home/ncvs/src/sys/vm/vm_mmap.c,v
% Working file: vm_mmap.c
% head: 1.177
% ...
% ----------------------------
% revision 1.171
% date: 2003/11/10 01:37:40;  author: alc;  state: Exp;  lines: +8 -6
%  - The Open Group Base Specifications Issue 6 specifies that an munmap(2)
%    must return EINVAL if size is zero.  Submitted by: tegge
%  - In order to avoid a race condition in multithreaded applications, the
%    check and removal operations by munmap(2) must be in the same critical
%    section.  To accomodate this, vm_map_check_protection() is modified to
%    require its caller to obtain at least a read lock on the map.
% ----------------------------

% RCS file: /home/ncvs/src/bin/cp/utils.c,v
% Working file: utils.c
% head: 1.42
% ...
% ----------------------------
% revision 1.42
% date: 2003/11/13 05:26:55;  author: alc;  state: Exp;  lines: +2 -1
% Don't mmap(2) and munmap(2) zero-length files.
%
% Submitted by:	Wiktor Niesiobedzki <bsd_at_w.evip.pl>
% ----------------------------

Note that only munmap(2) is specified to be (or implemented to be) broken.
You can mmap() zero-length files, but you can't munmap() them.

Bruce