git-cvsserver(1)
NAME
git-cvsserver - A CVS server emulator for Git
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> ...]
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.
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.
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.
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 can not 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
alpha-numeric 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.
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 PreferencesTeamCVSExtConnection 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.
GIT
Part of the git(1) suite
Opportunity
Personal Opportunity - Free software gives you access to billions of dollars of software at no cost. Use this software for your business, personal use or to develop a profitable skill. Access to source code provides access to a level of capabilities/information that companies protect though copyrights. Open source is a core component of the Internet and it is available to you. Leverage the billions of dollars in resources and capabilities to build a career, establish a business or change the world. The potential is endless for those who understand the opportunity.
Business Opportunity - Goldman Sachs, IBM and countless large corporations are leveraging open source to reduce costs, develop products and increase their bottom lines. Learn what these companies know about open source and how open source can give you the advantage.
Free Software
Free Software provides computer programs and capabilities at no cost but more importantly, it provides the freedom to run, edit, contribute to, and share the software. The importance of free software is a matter of access, not price. Software at no cost is a benefit but ownership rights to the software and source code is far more significant.
Free Office Software - The Libre Office suite provides top desktop productivity tools for free. This includes, a word processor, spreadsheet, presentation engine, drawing and flowcharting, database and math applications. Libre Office is available for Linux or Windows.
Free Books
The Free Books Library is a collection of thousands of the most popular public domain books in an online readable format. The collection includes great classical literature and more recent works where the U.S. copyright has expired. These books are yours to read and use without restrictions.
Source Code - Want to change a program or know how it works? Open Source provides the source code for its programs so that anyone can use, modify or learn how to write those programs themselves. Visit the GNU source code repositories to download the source.
Education
Study at Harvard, Stanford or MIT - Open edX provides free online courses from Harvard, MIT, Columbia, UC Berkeley and other top Universities. Hundreds of courses for almost all major subjects and course levels. Open edx also offers some paid courses and selected certifications.
Linux Manual Pages - A man or manual page is a form of software documentation found on Linux/Unix operating systems. Topics covered include computer programs (including library and system calls), formal standards and conventions, and even abstract concepts.
