Import vixie cron 4.0

Specifically, import the diff from commit e745bd4c10ab to
commit 83563783cc2 in https://github.com/vixie/cron.git

My sole motivation is changing to the common MIT license.
The old license, especially the "buildable source" clause,
is unfriendly for commercial users of this code. Simply
changing the license without importing [most of] the code
accompanying that license seemed legally dubious.

The most regrettable change is losing Paul's uucp path.
I partially atone for this loss by restoring the upstream
$Id$ tags, since $FreeBSD$ is no longer useful.

This is [intended to be] a complete list of the functional
changes in this commit. Some changes were made so that we
could consider vixie cron to be our upstream and reduce our
diffs against it, while others were simply a good idea.

- main() - use putenv instead of setenv for PATH
- open_pidfile no longer needs snprintf to build pidfile
- crontab main() - abort() on impossible errors
- check for truncation when building strings with snprintf
- getdtablesize() -> sysconf(_SC_OPEN_MAX)

These changes were not taken from upstream's 4.0 diff because
they [could] actually change behavior. Some of them might be
beneficial, but should be taken separately.

- config.h - sendmail args: remove -oi and add -or0s
- call setlocale(LC_ALL, "") at the top of main()
- acquire_daemonlock - we already use pidfile
- cast getpid(), uid_t, and gid_t to long for printf
- remove unnecessary braces - I consider them beneficial
- BSDi support
- glue_strings() - use snprintf(), as we often already did

MFC after: on demand
Sponsored by: Dell EMC Isilon
Differential Revision: https://reviews.freebsd.org/D40260

cron: Use C89 function definitions.

Reviewed by: zlei
Differential Revision: https://reviews.freebsd.org/D39529

Add a 'force' option for non-interactive crontab removal

Add a '-f' option to force crontab '-r' to be non-interactive.

Submitted by: Sam Gwydir <sam at samgwydir.com>
Reviewed by: me, wblock (previous version)
Sponsored by: Dell EMC Isilon
Differential Revision: https://reviews.freebsd.org/D8815

cron: use existing maximum username constant MAXLOGNAME

Previously cron had its own maximum username length limit, which was
smaller than the system's MAXLOGNAME. This could lead to crontab -u
updating the wrong user's crontab (if the name was truncated, and
matched another user).

PR: 212305
Reported by: Andrii Kuzik
Reviewed by: allanjude, jilles
MFC after: 3 days
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D7747

crontab: ftruncate() with ftello() instead of ftell().

Obtained from: OpenBSD (CVS rev. 1.47)

crontab: properly free an entry

This should close memory leak.

Obtained from: OpenBSD (rev. 1.62)
CID: 271773

Rework all non-contributed files that use `struct timezone'.

This structure is not part of POSIX. According to POSIX, gettimeofday()
has the following prototype:

int gettimeofday(struct timeval *restrict tp, void *restrict tzp);

Also, POSIX states that gettimeofday() shall return 0 (as long as tzp is
not used). Remove dead error handling code. Also use NULL for a
nul-pointer instead of integer 0.

While there, change all pieces of code that only use tv_sec to use
time(3), as this provides less overhead.

Add a one second sleep before touching the spool directory. If the touch
occurs in the same second as the earlier operations to create the temporary
file and the cron(8) daemon is rescans the spool directory during that
second, then the daemon may miss a cron edit and not properly update its
internal database.

MFC after: 1 month

Drop setuid status while doing file operations to prevent potential
information leak. This changeset is intended to be a minimal one
to make backports easier.

Reviewed by: kevlo, remko
MFC after: 1 week

A new jail(8) with a configuration file, to replace the work currently done
by /etc/rc.d/jail.

Create the altix project branch. The altix project will add support
for the SGI Altix 350 to FreeBSD/ia64. The hardware used for porting
is a two-module system, consisting of a base compute module and a
CPU expansion module. SGI's NUMAFlex architecture can be an excellent
platform to test CPU affinity and NUMA-aware features in FreeBSD.

Be more precise and use sizeof(tn)
Pointed out by: glewis@

MFC after: 3 days

Make usr.sbin/cron/crontab and usr.sbin/cron/lib WARNS=3 clean

Tested with: make universe

MFC after: 3 days

Revert to previous revision.
I should not commit anything at 3.50 AM.
In addition to danfe's comments, I got others.
I'll work on a better version of the patch.

Don't leave files in /var/cront/tabs when interrupted

PR: 17363
MFC after: 3 days

Be paranoid and use snprintf

PR: bin/122137
Submitted by: Steven Kreuzer <skreuzer@exit2shell.com>
MFC after: 3 days

Be paranoid and zero out passwd

PR: 122070
Submitted by: Steven Kreuzer <skreuzer@exit2shell.com>
Reminded by: gnn@
MFC after: 3 days

- Import the HEAD csup code which is the basis for the cvsmode work.

Cleanup of userland __P use

Use a #define to refer to /etc/crontab.

/etc/crontab is similar enough to parse as correct if you run
"crontab /etc/crontab", but not the same format due to the who field.
Add some limited anti-foot-shooting support and refuse to load
/etc/crontab as someone's crontab. Users wishing shoot their foot in
this manner may copy /etc/crontab elsewhere. :)

MFC After: 1 week

Ensure that edits that do not span a clock tick are not lost.

PR: bin/22612
MT5: 4 weeks
MT4: 2 weeks

Refactoring: move two similar code blocks into a seprate function.

Fix for the following behavior:
$ crontab -e
[Add an entry with an error in the crontab file.]
crontab: errors in crontab file, can't install
Do you want to retry the same edit? yes
[Exit the editor without any changes.]
crontab: no changes made to crontab
[Entry is lost.]

Now crontab will loop until the error is fixed, or the
user answers no.

Actually use the exitstatus value that we maintain.

PR: 43562
Submitted by: Marc Olzheim <marcolz@ilse.nl>

Fix the type of the NULL arg to execl()

Idea from: Theo de Raadt <deraadt@openbsd.org>

Where is the pointy hat? Fix cut/paste error. (hey, it compiled! :-)

Remove the 'DO NOT EDIT THIS FILE' crud that we spit out with 'crontab -l'.
Otherwise, "crontab -l > file; vi file; crontab file" adds an extra set
of "DO NOT EDIT" markers each and every time which is a bit silly.

Add `_PATH_DEVZERO'.
Use _PATH_* where where possible.

Attempt to fix problem with users being able to convince the crontab
program to read any file which is a valid crontab file.

The fix is based on that used in NetBSD and OpenBSD - we keep the
file open while the user is editing it. This means that files must
be edited in place. Cron attempts to warn you if your editor does
not do this. The fact that the file must be edited in place is also
noted in the man page.

This patch has been confirmed to work by atleast one person on
-security and has been tested locally.

Obtained from: OpenBSD

Since -e and -r are right next to each other prompt before clobbering
a crontab you were planning to edit.

$Id$ -> $FreeBSD$

Use err(3). Rewrote man page in mdoc format.

compare return value from getopt against -1 rather than EOF, per the final
posix standard on the topic.

Revert $FreeBSD$ to $Id$

Make the long-awaited change from $Id$ to $FreeBSD$

This will make a number of things easier in the future, as well as (finally!)
avoiding the Id-smashing problem which has plagued developers for so long.

Boy, I'm glad we're not using sup anymore. This update would have been
insane otherwise.

Replace my "inane" usage of snprintf to copy strings with strncpy as
used by OpenBSD. (Quite frankly, I think it's perfectly reasonable to
use snprintf to copy strings, given that the semantics for strncpy()
are utterly idiotic and there is no POSIX sstrncpy().)

While I'm at it, incorporate some of OpenBSD's bugfixes to cron.

NOT for 2.2

Gratuitous whitespace change so that I can commit the source of the recent
buffer overflow patch.
Reviewed by: pst
Submitted by: Dave Andersen <angio@aros.net>

Fix up some more buffer overflow problems.

Quick patch to fix a bug where issuing ctl-c while in crontab -e
leaves editor running in background (PR: bin/751)

Submitted by: candy@fct.kgc.co.jp (Toshihiro Kanda)

Remove trailing whitespace.

Now crontab works not only for vi editor, i.e. refers to
file name not to file fd

Paul Vixie's cron, version 3.0. Munged into bmake format. If this goes
well, expect our two seperate directories for cron and crontab to go away
shortly.
Submitted by: jkh