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CTM_MAIL(1)             FreeBSD General Commands 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.  The
     ctm_smail utility 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
     automatically) 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
             informational 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
             overwhelming users' mail boxes.  Note that this is the size
             before encoding.  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
             allows 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
             informational 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
     separate 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
             informational 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
             corresponds to a single mail message.  Pieces are removed when
             complete 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
             probably 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,
             causing 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.  Do not worry about zillions of background ctm
             processes 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
             appears 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
     entire maildrop can be scanned and processed with a single command.

     It is safe to invoke ctm_rmail multiple times concurrently (with
     different 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
     simple checksum.

     If the delta exceeds maxctmsize, then a message like this will be
     received 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 ftp.

     You are then on your own!

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
             applied to this source tree.

EXIT STATUS
     The ctm_smail, ctm_dequeue and ctm_rmail utilities return exit status 0
     for success, and 1 for various failures.  The ctm_rmail utility 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.

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
     complete 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
     decode and assemble deltas, but not apply them, you could put the
     following lines in your /etc/mail/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
     mailbox, 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(1) on
     the (non-FreeBSD) machine that this example was taken from.

SECURITY
     On its own, CTM is an insecure protocol - there is no authentication
     performed that the changes applied to the source code were sent by a
     trusted party, and so care should be taken if the CTM deltas are obtained
     via an unauthenticated medium such as regular email.  It is a relatively
     simple matter for an attacker to forge a CTM delta to replace or precede
     the legitimate one and insert malicious code into your source tree.  If
     the legitimate delta is somehow prevented from arriving, this will go
     unnoticed until a later delta attempts to touch the same file, at which
     point the MD5 checksum will fail.

     To remedy this insecurity, CTM delta pieces generated by FreeBSD.org are
     cryptographically signed in a format compatible with the GNU Privacy
     Guard utility, available in /usr/ports/security/gpg, and the Pretty Good
     Privacy v5 utility, /usr/ports/security/pgp5.  The relevant public key
     can be obtained by fingering ctm@FreeBSD.org.

     CTM deltas which are thus signed cannot be undetectably altered by an
     attacker.  Therefore it is recommended that you make use of GPG or PGP5
     to verify the signatures if you receive your CTM deltas via email.

DIAGNOSTICS
     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

     The ctm_dequeue utility will report messages like:

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

     The ctm_rmail utility 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(1)
     turn up here too.  Error messages should be self explanatory.

SEE ALSO
     ctm(1), ctm(5)

AUTHORS
     Stephen McKay <mckay@FreeBSD.org>

FreeBSD 11.0-PRERELEASE        January 24, 1995        FreeBSD 11.0-PRERELEASE

NAME | SYNOPSIS | DESCRIPTION | FILE FORMAT | ENVIRONMENT | FILES | EXIT STATUS | EXAMPLES | SECURITY | DIAGNOSTICS | SEE ALSO | AUTHORS

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