The
utility was originally
``Cvs Through eMail''
but now instead it seems more fitting to call it
``Current Through eMail''
The
utility is now meant to be the definitive way to make and apply a delta between
two versions of a directory tree.
There are two parts to this, making the delta and applying it.
These are two
entirely different things.
Usage
To apply a CTM delta, you pass it to the
command.
You can pass a CTM delta on stdin, or you can give the
filename as an argument.
If you do the latter, you make life a lot
easier for your self, since the program can accept gzip'ed files and
since it will not have to make a temporary copy of your file.
You can
specify multiple deltas at one time, they will be processed one at a
time.
Deltas that are already applied will be ignored.
The
command runs in a number of passes.
It will process the entire
input file in each pass, before commencing with the next pass.
Before working on a file
name
first checks for the existence of the file
name.ctm
If this file exists,
works on it instead.
Pass 1 will verify that the input file is OK.
The syntax, the data
and the global MD5 checksum will be checked.
If any of these fail,
will simply reject the input file.
Pass 2 will validate that the directory tree is in the state expected by
the CTM delta.
This is done by looking for files and directories which
should/should not exist and by checking the MD5 checksums of files.
If a
backup-file
had been specified using the
-B
option, all files that would be modified by this
invocation are backed up
to this file using the archiver command specified by the
-t
option.
The default archiver command is
tar -rf %s -T -
Pass 3 will actually apply the delta.
The list of files that would be modified by
is subject to filtering regular expressions specified
using the
-e
and
-x
options.
The
-e
and
-x
options are applied in order of appearance on the command line.
The last
filter that matched a given file name determines whether the file would be
operated on or left alone by
.
The
utility
will extract the file hierarchy below its working directory.
Absolute
filenames or filenames containing references through
`.
'
and
`..
'
are explicitly prohibited as a security measure.
Options
-b basedir
Prepend the path
basedir
to every filename.
-B backup-file
Backup all files that would be modified by this CTM run to
backup-file
If any filters are specified using the
-e
and
-x
options, then the final set of files backed up are those that would be
modified by CTM after the filters are applied.
-c
Check it out, do not do anything.
-e regular_expression
Match each name in the CTM file against
regular_expression
and if it matches process the file, otherwise leave it alone.
There may be
any number of these options.
Use of this option disables the
.ctm_status
sequence number checks.
For example, the expression
^usr.sbin/ctm
for example, will select the
usr.sbin/ctm
source directory and all pathnames under it.
Pathnames can be disabled from being considered by CTM using the
-x
option.
-F
Force.
-k
Keep files and directories and do not remove them even if the CTM file
specifies they are to be removed.
If the
-B
option is specified, these files and directories will not be backed up.
-l
List files that would be modified by this invocation of CTM and the
actions that would be performed on them.
Use of the
-l
option disables the
.ctm_status
checks and integrity checks on the source tree being operated on.
The
-l
option can be combined with the
-e
and
-x
options to determine which files would be modified by the given set of
command line options.
-q
Tell us less.
-t tar-command
Use
tar-command
instead of the default archiver
tar
This option takes effect only if a backup file had been specified using the
-B
option.
A %s in the tar command will be replaced by the name of the backup
file.
-T tmpdir
Put temporary files under
tmpdir
-u
Set modification time of created and modified files to the CTM delta
creation time.
-v
Tell us more.
-V level
Tell us more.
Level
is the level of verbosity.
-x regular_expression
Match each name in the CTM file against
regular_expression
and if it matches, leave the file alone.
There may be any number of these
options.
Use of this option disables the
.ctm_status
sequence number checks.
Pathnames can be selected for CTM's consideration using the
-e
option.
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 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 [email protected].
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.
ENVIRONMENT
TMPDIR
if set to a pathname, will cause ctm to use that pathname
as the location of temporary file.
See
tempnam(3),
for more details on this.
The same effect may be achieved with the
-T
flag.
FILES
.ctm_status
contains the sequence number of the last CTM delta applied.
Changing
or removing this file will greatly confuse
.
Using the
-e
and
-x
options can update a partial subset of the source tree and causes sources
to be in an inconsistent state.
It is assumed that you know what you are
doing when you use these options.
EXAMPLES
cd ~cvs
/usr/sbin/ctm ~ctm/cvs-*
To extract and patch all sources under `lib'
cd ~/lib-srcs
/usr/sbin/ctm -e '^lib' ~ctm/src-cur*
DIAGNOSTICS
Numerous messages, hopefully self-explanatory.
The
``noise level''
can be adjusted with the
-q
-v
and
-V
options.
