эмулятор сервера CVS для Git (A CVS server emulator for Git)
Имя (Name)
git-cvsserver - A CVS server emulator for Git
Синопсис (Synopsis)
SSH:
export CVS_SERVER="git cvsserver"
cvs -d :ext:user@server/path/repo.git co <HEAD_name>
pserver (/etc/inetd.conf):
cvspserver stream tcp nowait nobody /usr/bin/git-cvsserver git-cvsserver pserver
Usage:
git-cvsserver [<options>] [pserver|server] [<directory> ...]
Описание (Description)
This application is a CVS emulation layer for Git.
It is highly functional. However, not all methods are
implemented, and for those methods that are implemented, not all
switches are implemented.
Testing has been done using both the CLI CVS client, and the
Eclipse CVS plugin. Most functionality works fine with both of
these clients.
Параметры (Options)
All these options obviously only make sense if enforced by the
server side. They have been implemented to resemble the
git-daemon(1) options as closely as possible.
--base-path <path>
Prepend path to requested CVSROOT
--strict-paths
Don't allow recursing into subdirectories
--export-all
Don't check for gitcvs.enabled in config. You also have to
specify a list of allowed directories (see below) if you want
to use this option.
-V, --version
Print version information and exit
-h, -H, --help
Print usage information and exit
<directory>
You can specify a list of allowed directories. If no
directories are given, all are allowed. This is an additional
restriction, gitcvs access still needs to be enabled by the
gitcvs.enabled config option unless --export-all was given,
too.
Ограничения (Limitations)
CVS clients cannot tag, branch or perform Git merges.
git-cvsserver maps Git branches to CVS modules. This is very
different from what most CVS users would expect since in CVS
modules usually represent one or more directories.
Установка (Installation)
1. If you are going to offer CVS access via pserver, add a line
in /etc/inetd.conf like
cvspserver stream tcp nowait nobody git-cvsserver pserver
Note: Some inetd servers let you specify the name of the
executable independently of the value of argv[0] (i.e. the
name the program assumes it was executed with). In this case
the correct line in /etc/inetd.conf looks like
cvspserver stream tcp nowait nobody /usr/bin/git-cvsserver git-cvsserver pserver
Only anonymous access is provided by pserve by default. To
commit you will have to create pserver accounts, simply add a
gitcvs.authdb setting in the config file of the repositories
you want the cvsserver to allow writes to, for example:
[gitcvs]
authdb = /etc/cvsserver/passwd
The format of these files is username followed by the
encrypted password, for example:
myuser:$1Oyx5r9mdGZ2
myuser:$1$BA)@$vbnMJMDym7tA32AamXrm./
You can use the htpasswd facility that comes with Apache to
make these files, but Apache's MD5 crypt method differs from
the one used by most C library's crypt() function, so don't
use the -m option.
Alternatively you can produce the password with perl's
crypt() operator:
perl -e 'my ($user, $pass) = @ARGV; printf "%s:%s\n", $user, crypt($user, $pass)' $USER password
Then provide your password via the pserver method, for
example:
cvs -d:pserver:someuser:somepassword <at> server/path/repo.git co <HEAD_name>
No special setup is needed for SSH access, other than having
Git tools in the PATH. If you have clients that do not accept
the CVS_SERVER environment variable, you can rename
git-cvsserver to cvs.
Note: Newer CVS versions (>= 1.12.11) also support specifying
CVS_SERVER directly in CVSROOT like
cvs -d ":ext;CVS_SERVER=git cvsserver:user@server/path/repo.git" co <HEAD_name>
This has the advantage that it will be saved in your CVS/Root
files and you don't need to worry about always setting the
correct environment variable. SSH users restricted to
git-shell don't need to override the default with CVS_SERVER
(and shouldn't) as git-shell understands cvs to mean
git-cvsserver and pretends that the other end runs the real
cvs better.
2. For each repo that you want accessible from CVS you need to
edit config in the repo and add the following section.
[gitcvs]
enabled=1
# optional for debugging
logFile=/path/to/logfile
Note: you need to ensure each user that is going to invoke
git-cvsserver has write access to the log file and to the
database (see Database Backend. If you want to offer write
access over SSH, the users of course also need write access
to the Git repository itself.
You also need to ensure that each repository is "bare"
(without a Git index file) for cvs commit to work. See
gitcvs-migration(7).
All configuration variables can also be overridden for a
specific method of access. Valid method names are "ext" (for
SSH access) and "pserver". The following example
configuration would disable pserver access while still
allowing access over SSH.
[gitcvs]
enabled=0
[gitcvs "ext"]
enabled=1
3. If you didn't specify the CVSROOT/CVS_SERVER directly in the
checkout command, automatically saving it in your CVS/Root
files, then you need to set them explicitly in your
environment. CVSROOT should be set as per normal, but the
directory should point at the appropriate Git repo. As above,
for SSH clients not restricted to git-shell, CVS_SERVER
should be set to git-cvsserver.
export CVSROOT=:ext:user@server:/var/git/project.git
export CVS_SERVER="git cvsserver"
4. For SSH clients that will make commits, make sure their
server-side .ssh/environment files (or .bashrc, etc.,
according to their specific shell) export appropriate values
for GIT_AUTHOR_NAME, GIT_AUTHOR_EMAIL, GIT_COMMITTER_NAME,
and GIT_COMMITTER_EMAIL. For SSH clients whose login shell is
bash, .bashrc may be a reasonable alternative.
5. Clients should now be able to check out the project. Use the
CVS module name to indicate what Git head you want to check
out. This also sets the name of your newly checked-out
directory, unless you tell it otherwise with -d <dir_name>.
For example, this checks out master branch to the
project-master directory:
cvs co -d project-master master
DATABASE BACKEND
git-cvsserver uses one database per Git head (i.e. CVS module) to
store information about the repository to maintain consistent CVS
revision numbers. The database needs to be updated (i.e. written
to) after every commit.
If the commit is done directly by using git (as opposed to using
git-cvsserver) the update will need to happen on the next
repository access by git-cvsserver, independent of access method
and requested operation.
That means that even if you offer only read access (e.g. by using
the pserver method), git-cvsserver should have write access to
the database to work reliably (otherwise you need to make sure
that the database is up to date any time git-cvsserver is
executed).
By default it uses SQLite databases in the Git directory, named
gitcvs.<module_name>.sqlite. Note that the SQLite backend creates
temporary files in the same directory as the database file on
write so it might not be enough to grant the users using
git-cvsserver write access to the database file without granting
them write access to the directory, too.
The database cannot be reliably regenerated in a consistent form
after the branch it is tracking has changed. Example: For merged
branches, git-cvsserver only tracks one branch of development,
and after a git merge an incrementally updated database may track
a different branch than a database regenerated from scratch,
causing inconsistent CVS revision numbers. git-cvsserver has no
way of knowing which branch it would have picked if it had been
run incrementally pre-merge. So if you have to fully or partially
(from old backup) regenerate the database, you should be
suspicious of pre-existing CVS sandboxes.
You can configure the database backend with the following
configuration variables:
Configuring database backend
git-cvsserver uses the Perl DBI module. Please also read its
documentation if changing these variables, especially about
DBI->connect().
gitcvs.dbName
Database name. The exact meaning depends on the selected
database driver, for SQLite this is a filename. Supports
variable substitution (see below). May not contain semicolons
(;). Default: %Ggitcvs.%m.sqlite
gitcvs.dbDriver
Used DBI driver. You can specify any available driver for
this here, but it might not work. cvsserver is tested with
DBD::SQLite, reported to work with DBD::Pg, and reported not
to work with DBD::mysql. Please regard this as an
experimental feature. May not contain colons (:). Default:
SQLite
gitcvs.dbuser
Database user. Only useful if setting dbDriver, since SQLite
has no concept of database users. Supports variable
substitution (see below).
gitcvs.dbPass
Database password. Only useful if setting dbDriver, since
SQLite has no concept of database passwords.
gitcvs.dbTableNamePrefix
Database table name prefix. Supports variable substitution
(see below). Any non-alphabetic characters will be replaced
with underscores.
All variables can also be set per access method, see above.
Variable substitution
In dbDriver and dbUser you can use the following variables:
%G
Git directory name
%g
Git directory name, where all characters except for
alphanumeric ones, ., and - are replaced with _ (this
should make it easier to use the directory name in a
filename if wanted)
%m
CVS module/Git head name
%a
access method (one of "ext" or "pserver")
%u
Name of the user running git-cvsserver. If no name can be
determined, the numeric uid is used.
Окружение (Environment)
These variables obviate the need for command-line options in some
circumstances, allowing easier restricted usage through
git-shell.
GIT_CVSSERVER_BASE_PATH takes the place of the argument to
--base-path.
GIT_CVSSERVER_ROOT specifies a single-directory whitelist. The
repository must still be configured to allow access through
git-cvsserver, as described above.
When these environment variables are set, the corresponding
command-line arguments may not be used.
ECLIPSE CVS CLIENT NOTES
To get a checkout with the Eclipse CVS client:
1. Select "Create a new project → From CVS checkout"
2. Create a new location. See the notes below for details on how
to choose the right protocol.
3. Browse the modules available. It will give you a list of the
heads in the repository. You will not be able to browse the
tree from there. Only the heads.
4. Pick HEAD when it asks what branch/tag to check out. Untick
the "launch commit wizard" to avoid committing the .project
file.
Protocol notes: If you are using anonymous access via pserver,
just select that. Those using SSH access should choose the ext
protocol, and configure ext access on the
Preferences→Team→CVS→ExtConnection pane. Set CVS_SERVER to "git
cvsserver". Note that password support is not good when using
ext, you will definitely want to have SSH keys setup.
Alternatively, you can just use the non-standard extssh protocol
that Eclipse offer. In that case CVS_SERVER is ignored, and you
will have to replace the cvs utility on the server with
git-cvsserver or manipulate your .bashrc so that calling cvs
effectively calls git-cvsserver.
CLIENTS KNOWN TO WORK
• CVS 1.12.9 on Debian
• CVS 1.11.17 on MacOSX (from Fink package)
• Eclipse 3.0, 3.1.2 on MacOSX (see Eclipse CVS Client Notes)
• TortoiseCVS
OPERATIONS SUPPORTED
All the operations required for normal use are supported,
including checkout, diff, status, update, log, add, remove,
commit.
Most CVS command arguments that read CVS tags or revision numbers
(typically -r) work, and also support any git refspec (tag,
branch, commit ID, etc). However, CVS revision numbers for
non-default branches are not well emulated, and cvs log does not
show tags or branches at all. (Non-main-branch CVS revision
numbers superficially resemble CVS revision numbers, but they
actually encode a git commit ID directly, rather than represent
the number of revisions since the branch point.)
Note that there are two ways to checkout a particular branch. As
described elsewhere on this page, the "module" parameter of cvs
checkout is interpreted as a branch name, and it becomes the main
branch. It remains the main branch for a given sandbox even if
you temporarily make another branch sticky with cvs update -r.
Alternatively, the -r argument can indicate some other branch to
actually checkout, even though the module is still the "main"
branch. Tradeoffs (as currently implemented): Each new "module"
creates a new database on disk with a history for the given
module, and after the database is created, operations against
that main branch are fast. Or alternatively, -r doesn't take any
extra disk space, but may be significantly slower for many
operations, like cvs update.
If you want to refer to a git refspec that has characters that
are not allowed by CVS, you have two options. First, it may just
work to supply the git refspec directly to the appropriate CVS -r
argument; some CVS clients don't seem to do much sanity checking
of the argument. Second, if that fails, you can use a special
character escape mechanism that only uses characters that are
valid in CVS tags. A sequence of 4 or 5 characters of the form
(underscore ("_"), dash ("-"), one or two characters, and dash
("-")) can encode various characters based on the one or two
letters: "s" for slash ("/"), "p" for period ("."), "u" for
underscore ("_"), or two hexadecimal digits for any byte value at
all (typically an ASCII number, or perhaps a part of a UTF-8
encoded character).
Legacy monitoring operations are not supported (edit, watch and
related). Exports and tagging (tags and branches) are not
supported at this stage.
CRLF Line Ending Conversions
By default the server leaves the -k mode blank for all files,
which causes the CVS client to treat them as a text files,
subject to end-of-line conversion on some platforms.
You can make the server use the end-of-line conversion attributes
to set the -k modes for files by setting the gitcvs.usecrlfattr
config variable. See gitattributes(5) for more information about
end-of-line conversion.
Alternatively, if gitcvs.usecrlfattr config is not enabled or the
attributes do not allow automatic detection for a filename, then
the server uses the gitcvs.allBinary config for the default
setting. If gitcvs.allBinary is set, then file not otherwise
specified will default to -kb mode. Otherwise the -k mode is left
blank. But if gitcvs.allBinary is set to "guess", then the
correct -k mode will be guessed based on the contents of the
file.
For best consistency with cvs, it is probably best to override
the defaults by setting gitcvs.usecrlfattr to true, and
gitcvs.allBinary to "guess".
DEPENDENCIES
git-cvsserver depends on DBD::SQLite.
