CTM_MAIL(1)                OpenBSD Reference Manual                CTM_MAIL(1)

NAME
     ctm_smail, ctm_dequeue, ctm_rmail - send and receive ctm(1) deltas via
     mail

SYNOPSIS
     ctm_smail [-l log] [-m maxmsgsize] [-c maxctmsize] [-q queue-dir] ctm-
               delta mail-alias
     ctm_dequeue [-l log] [-n numchunks] queue-dir
     ctm_rmail [-Dfuv] [-l log] [-p piecedir] [-d deltadir] [-b basedir]
               [file ...]

DESCRIPTION
     In conjunction with the ctm(1) command, ctm_smail, ctm_dequeue and
     ctm_rmail are used to distribute changes to a source tree via email.
     ctm_smail is given a compressed ctm delta, and a mailing list to send it
     to.  It splits the delta into manageable pieces, encodes them as mail
     messages and sends them to the mailing list (optionally queued to spread
     the mail load).  Each recipient uses ctm_rmail (either manually or auto-
     matically) to decode and reassemble the delta, and optionally call ctm to
     apply it to the source tree.  At the moment, several source trees are
     distributed, and by several sites.  These include the FreeBSD-current
     source and CVS trees, distributed by freefall.FreeBSD.org.

     Command line arguments for ctm_smail:

     -l log  Instead of appearing on stderr, error diagnostics and informa-
             tional messages (other than command line errors) are time stamped
             and written to the file log.

     -m maxmsgsize
             Limit the maximum size mail message that ctm_smail is allowed to
             send.  It is approximate since mail headers and other niceties
             are not counted in this limit.  If not specified, it will default
             to 64000 bytes, leaving room for 1535 bytes of headers before the
             rumoured 64k mail limit.

     -c maxctmsize
             Limit the maximum size delta that will be sent.  Deltas bigger
             that this limit will cause an apology mail message to be sent to
             the mailing list.  This is to prevent massive changes overwhelm-
             ing users' mail boxes.  Note that this is the size before encod-
             ing.  Encoding causes a 4/3 size increase before mail headers are
             added.  If not specified, there is no limit.

     -q queue-dir
             Instead of mailing the delta pieces now, store them in the given
             directory to be mailed later using ctm_dequeue. This feature al-
             lows the mailing of large deltas to be spread out over hours or
             even days to limit the impact on recipients with limited network
             bandwidth or small mail spool areas.

     ctm-delta is the delta to be sent, and mail-alias is the mailing list to
     send the delta to.  The mail messages are sent using sendmail(8).

     Command line arguments for ctm_dequeue:

     -l log  Instead of appearing on stderr, error diagnostics and informa-
             tional messages (other than command line errors) are time stamped
             and written to the file log.

     -n numchunks
             Limit the number of mail messages that ctm_dequeue will send per
             run.  By default, ctm_dequeue will send one mail message per run.

     queuedir is the directory containing the mail messages stored by
     ctm_smail. Up to numchunks mail messages will be sent in each run.  The
     recipient mailing list is already encoded in the queued files.

     It is safe to run ctm_dequeue while ctm_smail is adding entries to the
     queue, or even to run ctm_smail multiple times concurrently, but a sepa-
     rate queue directory should be used for each tree being distributed.
     This is because entries are served in alphabetical order, and one tree
     will be unfairly serviced before any others, based on the delta names,
     not delta creation times.

     Command line arguments for ctm_rmail:

     -l log  Instead of appearing on stderr, error diagnostics and informa-
             tional messages (other than command line errors) are time stamped
             and written to the file log.

     -p piecedir
             Collect pieces of deltas in this directory.  Each piece corre-
             sponds to a single mail message.  Pieces are removed when com-
             plete deltas are built.  If this flag is not given, no input
             files will be read, but completed deltas may still be applied
             with ctm if the -b flag is given.

     -d deltadir
             Collect completed deltas in this directory.  Deltas are built
             from one or more pieces when all pieces are present.

     -b basedir
             Apply any completed deltas to this source tree.  If this flag is
             not given, deltas will be stored, but not applied.  The user may
             then apply the deltas manually, or by using ctm_rmail without the
             -p flag.  Deltas will not be applied if they do not match the
             .ctm_status file in basedir (or if .ctm_status does not exist).

     -D      Delete deltas after successful application by ctm.  It is proba-
             bly a good idea to avoid this flag (and keep all the deltas) as
             ctm has the ability to recover small groups of files from a full
             set of deltas.

     -f      Fork and execute in the background while applying deltas with
             ctm.  This is useful when automatically invoking ctm_rmail from
             sendmail because ctm can take a very long time to complete, caus-
             ing other people's mail to be delayed, and can in theory cause
             spurious mail retransmission due to the remote sendmail timing
             out, or even termination of ctm_rmail by mail filters such as
             MH's slocal.  Don't worry about zillions of background ctm pro-
             cesses loading your machine, since locking is used to prevent
             more than one ctm invocation at a time.

     -u      Pass the -u flag to the ctm command when applying the complete
             deltas, causing it to set the modification time of created and
             modified files to the CTM delta creation time.

     -v      Pass the -v flag to the ctm command when applying the complete
             deltas, causing a more informative output.  All ctm output ap-
             pears in the ctm_rmail log file.

     The file arguments (or stdin, if there are none) are scanned for delta
     pieces.  Multiple delta pieces can be read from a single file, so an en-
     tire maildrop can be scanned and processed with a single command.

     It is safe to invoke ctm_rmail multiple times concurrently (with differ-
     ent input files), as might happen when sendmail is delivering mail
     asynchronously.  This is because locking is used to keep things orderly.

FILE FORMAT
     Following are the important parts of an actual (very small) delta piece:

     From: owner-src-cur
     To: src-cur
     Subject: ctm-mail src-cur.0003.gz 1/4

     CTM_MAIL BEGIN src-cur.0003.gz 1 4
     H4sIAAAAAAACA3VU72/bNhD9bP0VByQoEiyRSZEUSQP9kKTeYCR2gDTdsGFAwB/HRogtG5K8NCj6
     v4+UZSdtUQh6Rz0eee/xaF/dzx8up3/MFlDkBNrGnbttAwyo1pxoRgoiBNX/QJ5d3c9/X8DcPGGo
     lggkPiXngE4W1gUjKPJCYyk5MZRbIqmNW/ASglIFcdwIzTUxaAqhnCPcBqloKEkJVNDMF0Azk+Bo
     dDzzk0Ods/+A5gXv9YyJHjMCtJwQNeESNma7hOmXDRxn
     CTM_MAIL END 61065

     The subject of the message always begins with ``ctm-mail'' followed by
     the name of the delta, which piece this is, and how many total pieces
     there are.  The data are bracketed by ``CTM_MAIL BEGIN'' and ``CTM_MAIL
     END'' lines, duplicating the information in the subject line, plus a sim-
     ple checksum.

     If the delta exceeds maxctmsize, then a message like this will be re-
     ceived instead:

     From: owner-src-cur
     To: src-cur
     Subject: ctm-notice src-cur.0999.gz

     src-cur.0999.gz is 792843 bytes.  The limit is 300000 bytes.

     You can retrieve this delta via ftpmail, or your good mate at the university.

     You are then on your own!

EXAMPLES
     To send delta 32 of src-cur to a group of wonderful code hackers known to
     sendmail as src-guys, limiting the mail size to roughly 60000 bytes, you
     could use:

           ctm_smail -m 60000 /wherever/it/is/src-cur.0032.gz src-guys

     To decode every ctm-mail message in your mailbox, assemble them into com-
     plete deltas, then apply any deltas built or lying around, you could use:

           ctm_rmail -p ~/pieces -d ~/deltas -b /usr/ctm-src-cur $MAIL

     (Note that no messages are deleted by ctm_rmail. Any mail reader could be
     used for that purpose.)

     To create a mail alias called receiver-dude that will automatically de-
     code and assemble deltas, but not apply them, you could put the following
     lines in your /etc/aliases file (assuming the /ctm/tmp and /ctm/deltas
     directories and /ctm/log file are writable by user ``daemon'' or group
     ``wheel''):

           receiver-dude: "|ctm_rmail -p /ctm/tmp -d /ctm/deltas -l /ctm/log"
           owner-receiver-dude: real_dude@wherever.you.like

     The second line will catch failures and drop them into your regular mail-
     box, or wherever else you like.

     To apply all the deltas collected, and delete those applied, you could
     use:

           ctm_rmail -D -d /ctm/deltas -b /ctm/src-cur -l /ctm/apply.log

     For maximum flexibility, consider this excerpt from a procmail script:

           PATH=$HOME/bin:$PATH

           :0 w
           * ^Subject: ctm-mail cvs-cur
           | ctm_incoming

     together with the shell script ~/bin/ctm_incoming:

           #! /bin/sh
           PATH="$HOME/bin:/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin"
           export PATH

           cd $HOME/ctm && ctm_rmail -f -p pieces -d deltas -l log -b /ctm

     which will deposit all ctm deltas in ~/ctm/deltas, apply them to the tree
     in /ctm, and drop any failures into your regular mail box.  Note the PATH
     manipulation in ctm_incoming which allows ctm_rmail to execute ctm on the
     (non-OpenBSD) machine that this example was taken from.

SECURITY
     If you automatically take your mail and pass it to a file tree patcher,
     you might think you are handing the keys to your system to the crackers!
     Happily, the window for mischief is quite small.  ctm_rmail is careful to
     write only to the directories given to it (by not believing any ``/''
     characters in the delta name), and the latest ctm disallows absolute
     pathnames and ``..'' in files it manipulates, so the worst you could lose
     are a few source tree files (recoverable from your deltas).  Since ctm
     requires that a md5 checksum match before it touches a file, only fellow
     source recipients would be able to generate a fake delta, and they're
     such nice folk that they wouldn't even think of it! :-)

     Even this possibility could be removed by using cryptographic signatures.
     A possible future enhancement would be to use PGP to provide a secure
     wrapper.

ENVIRONMENT
     If deltas are to be applied then ctm(1) and gunzip(1) must be in your
     PATH.

FILES
     QUEUEDIR/*
             Pieces of deltas encoded as mail messages waiting to be sent to
             the mailing list.

     PIECEDIR/*
             Pieces of deltas waiting for the rest to arrive.

     DELTADIR/*
             Completed deltas.

     BASEDIR/.ctm_status
             File containing the name and number of the next delta to be ap-
             plied to this source tree.

DIAGNOSTICS
     ctm_smail, ctm_dequeue and ctm_rmail return exit status 0 for success,
     and 1 for various failures.  ctm_rmail is expected to be called from a
     mail transfer program, and thus signals failure only when the input mail
     message should be bounced (preferably into your regular maildrop, not
     back to the sender).  In short, failure to apply a completed delta with
     ctm is not considered an error important enough to bounce the mail, and
     ctm_rmail returns an exit status of 0.

     In normal operation, ctm_smail will report messages like:

           ctm_smail: src-cur.0250.gz 1/2 sent to src-guys

     or, if queueing,

           ctm_smail: src-cur.0250.gz 1/2 queued for src-guys

     ctm_dequeue will report messages like:

           ctm_dequeue: src-cur.0250.gz 1/2 sent

     ctm_rmail will report messages like:

           ctm_rmail: src-cur.0250.gz 1/2 stored
           ctm_rmail: src-cur.0250.gz 2/2 stored
           ctm_rmail: src-cur.0250.gz complete

     If any of the input files do not contain a valid delta piece, ctm_rmail
     will report:

           ctm_rmail: message contains no delta

     and return an exit status of 1.  You can use this to redirect wayward
     messages back into your real mailbox if your mail filter goes wonky.

     These messages go to stderr or to the log file.  Messages from ctm turn
     up here too.  Error messages should be self explanatory.

SEE ALSO
     ctm(1),  ctm(5)

AUTHOR
     Stephen McKay <syssgm@devetir.qld.gov.au>

OpenBSD 2.6                    January 24, 1995                              5
