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<div class="top-level-extent" id="Top">
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<p>
Next: <a href="#Introduction" accesskey="n" rel="next">Introduction</a> </p>
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<h1 class="top" id="CVS-Client_002fServer"><span>CVS Client/Server<a class="copiable-link" href="#CVS-Client_002fServer"> ¶</a></span></h1>
<p>This document describes the client/server protocol used by CVS. It does
not describe how to use or administer client/server CVS; for that,
see <a data-manual="cvs" href="https://www.gnu.org/software/trans-coord/manual/cvs/cvs.html#Top">the regular CVS manual</a> in <cite class="cite">the regular CVS manual</cite>.
This specification applies to
<small class="sc">CVS</small> version 1.12.13-MirOS-0AB9.1 and up.
</p>
<ul class="mini-toc">
<li><a href="#Introduction" accesskey="1">Introduction</a></li>
<li><a href="#Goals" accesskey="2">Goals</a></li>
<li><a href="#Connection-and-Authentication" accesskey="3">How to Connect to and Authenticate Oneself to the CVS server</a></li>
<li><a href="#Password-scrambling" accesskey="4">Password scrambling algorithm</a></li>
<li><a href="#Protocol" accesskey="5">The CVS client/server protocol</a></li>
<li><a href="#Protocol-Notes" accesskey="6">Notes on the Protocol</a></li>
</ul>
<hr>
<div class="chapter-level-extent" id="Introduction">
<div class="nav-panel">
<p>
Next: <a href="#Goals" accesskey="n" rel="next">Goals</a>, Previous: <a href="#Top" accesskey="p" rel="prev">CVS Client/Server</a>, Up: <a href="#Top" accesskey="u" rel="up">CVS Client/Server</a> </p>
</div>
<h2 class="chapter" id="Introduction-1"><span>1 Introduction<a class="copiable-link" href="#Introduction-1"> ¶</a></span></h2>
<p>CVS is a version control system (with some additional configuration
management functionality). It maintains a central <em class="dfn">repository</em>
which stores files (often source code), including past versions,
information about who modified them and when, and so on. People who
wish to look at or modify those files, known as <em class="dfn">developers</em>, use
CVS to <em class="dfn">check out</em> a <em class="dfn">working directory</em> from the repository, to
<em class="dfn">check in</em> new versions of files to the repository, and other
operations such as viewing the modification history of a file. If
developers are connected to the repository by a network, particularly a
slow or flaky one, the most efficient way to use the network is with the
CVS-specific protocol described in this document.
</p>
<p>Developers, using the machine on which they store their working
directory, run the CVS <em class="dfn">client</em> program. To perform operations
which cannot be done locally, it connects to the CVS <em class="dfn">server</em>
program, which maintains the repository. For more information on how
to connect see <a class="ref" href="#Connection-and-Authentication">How to Connect to and Authenticate Oneself to the CVS server</a>.
</p>
<p>This document describes the CVS protocol. Unfortunately, it does not
yet completely document one aspect of the protocol—the detailed
operation of each CVS command and option—and one must look at the CVS
user documentation, <samp class="file">cvs.texinfo</samp>, for that information. The
protocol is non-proprietary (anyone who wants to is encouraged to
implement it) and an implementation, known as CVS, is available under
the GNU General Public License. The CVS distribution, containing this
implementation, <samp class="file">cvs.texinfo</samp>, and a copy (possibly more or less up
to date than what you are reading now) of this document,
<samp class="file">cvsclient.texi</samp>, can be found at the usual GNU FTP sites, with a
filename such as <samp class="file">cvs-<var class="var">version</var>.tar.gz</samp>.
</p>
<p>This is version 1.12.13 of the protocol specification. This
version number is intended only to aid in distinguishing different
versions of this specification. Although the specification is currently
maintained in conjunction with the CVS implementation, and carries the
same version number, it also intends to document what is involved with
interoperating with other implementations (such as other versions of
CVS); see <a class="ref" href="#Requirements">Required versus optional parts of the protocol</a>. This version number should not be used
by clients or servers to determine what variant of the protocol to
speak; they should instead use the <code class="code">valid-requests</code> and
<code class="code">Valid-responses</code> mechanism (see <a class="pxref" href="#Protocol">The CVS client/server protocol</a>), which is more
flexible.
</p>
<hr>
</div>
<div class="chapter-level-extent" id="Goals">
<div class="nav-panel">
<p>
Next: <a href="#Connection-and-Authentication" accesskey="n" rel="next">How to Connect to and Authenticate Oneself to the CVS server</a>, Previous: <a href="#Introduction" accesskey="p" rel="prev">Introduction</a>, Up: <a href="#Top" accesskey="u" rel="up">CVS Client/Server</a> </p>
</div>
<h2 class="chapter" id="Goals-1"><span>2 Goals<a class="copiable-link" href="#Goals-1"> ¶</a></span></h2>
<ul class="itemize mark-bullet">
<li>Do not assume any access to the repository other than via this protocol.
It does not depend on NFS, rdist, etc.
</li><li>Providing a reliable transport is outside this protocol. The protocol
expects a reliable transport that is transparent (that is, there is no
translation of characters, including characters such as
linefeeds or carriage returns), and can transmit all 256 octets (for
example for proper handling of binary files, compression, and
encryption). The encoding of characters specified by the protocol (the
names of requests and so on) is the invariant ISO 646 character set (a
subset of most popular character sets including ASCII and others). For
more details on running the protocol over the TCP reliable transport,
see <a class="ref" href="#Connection-and-Authentication">How to Connect to and Authenticate Oneself to the CVS server</a>.
</li><li>Security and authentication are handled outside this protocol (but see
below about ‘<samp class="samp">cvs kserver</samp>’ and ‘<samp class="samp">cvs pserver</samp>’).
</li><li>The protocol makes it possible for updates to be atomic with respect to
checkins; that is if someone commits changes to several files in one cvs
command, then an update by someone else would either get all the
changes, or none of them. The current <small class="sc">CVS</small> server can’t do this,
but that isn’t the protocol’s fault.
</li><li>The protocol is, with a few exceptions, transaction-based. That is, the
client sends all its requests (without waiting for server responses),
and then waits for the server to send back all responses (without
waiting for further client requests). This has the advantage of
minimizing network turnarounds and the disadvantage of sometimes
transferring more data than would be necessary if there were a richer
interaction. Another, more subtle, advantage is that there is no need
for the protocol to provide locking for features such as making checkins
atomic with respect to updates. Any such locking can be handled
entirely by the server. A good server implementation (such as the
current <small class="sc">CVS</small> server) will make sure that it does not have any such
locks in place whenever it is waiting for communication with the client;
this prevents one client on a slow or flaky network from interfering
with the work of others.
</li><li>It is a general design goal to provide only one way to do a given
operation (where possible). For example, implementations have no choice
about whether to terminate lines with linefeeds or some other
character(s), and request and response names are case-sensitive. This
is to enhance interoperability. If a protocol allows more than one way
to do something, it is all too easy for some implementations to support
only some of them (perhaps accidentally).
</li></ul>
<hr>
</div>
<div class="chapter-level-extent" id="Connection-and-Authentication">
<div class="nav-panel">
<p>
Next: <a href="#Password-scrambling" accesskey="n" rel="next">Password scrambling algorithm</a>, Previous: <a href="#Goals" accesskey="p" rel="prev">Goals</a>, Up: <a href="#Top" accesskey="u" rel="up">CVS Client/Server</a> </p>
</div>
<h2 class="chapter" id="How-to-Connect-to-and-Authenticate-Oneself-to-the-CVS-server"><span>3 How to Connect to and Authenticate Oneself to the CVS server<a class="copiable-link" href="#How-to-Connect-to-and-Authenticate-Oneself-to-the-CVS-server"> ¶</a></span></h2>
<p>Connection and authentication occurs before the CVS protocol itself is
started. There are several ways to connect.
</p>
<dl class="table">
<dt>server</dt>
<dd><p>If the client has a way to execute commands on the server, and provide
input to the commands and output from them, then it can connect that
way. This could be the usual rsh (port 514) protocol, Kerberos rsh,
SSH, or any similar mechanism. The client may allow the user to specify
the name of the server program; the default is <code class="code">cvs</code>. It is
invoked with one argument, <code class="code">server</code>. Once it invokes the server,
the client proceeds to start the cvs protocol.
</p>
</dd>
<dt>kserver</dt>
<dd><p>The kerberised server listens on a port (in the current implementation,
by having inetd call "cvs kserver") which defaults to 1999. The client
connects, sends the usual kerberos authentication information, and then
starts the cvs protocol. Note: port 1999 is officially registered for
another use, and in any event one cannot register more than one port for
CVS, so GSS-API (see below) is recommended instead of kserver as a way
to support kerberos.
</p>
</dd>
<dt>pserver</dt>
<dd><p>The name <em class="dfn">pserver</em> is somewhat confusing. It refers to both a
generic framework which allows the CVS protocol to support several
authentication mechanisms, and a name for a specific mechanism which
transfers a username and a cleartext password. Servers need not support
all mechanisms, and in fact servers will typically want to support only
those mechanisms which meet the relevant security needs.
</p>
<p>The pserver server listens on a port (in the current
implementation, by having inetd call "cvs pserver") which defaults to
2401 (this port is officially registered). The client
connects, and sends the following:
</p>
<ul class="itemize mark-bullet">
<li>the string ‘<samp class="samp">BEGIN AUTH REQUEST</samp>’, a linefeed,
</li><li>the cvs root, a linefeed,
</li><li>the username, a linefeed,
</li><li>the password trivially encoded (see <a class="ref" href="#Password-scrambling">Password scrambling algorithm</a>), a
linefeed,
</li><li>the string ‘<samp class="samp">END AUTH REQUEST</samp>’, and a linefeed.
</li></ul>
<p>The client must send the
identical string for cvs root both here and later in the
<code class="code">Root</code> request of the cvs
protocol itself. Servers are encouraged to enforce this restriction.
The possible server responses (each of which is followed by a linefeed)
are the following. Note that although there is a small similarity
between this authentication protocol and the cvs protocol, they are
separate.
</p>
<dl class="table">
<dt><code class="code">I LOVE YOU</code></dt>
<dd><p>The authentication is successful. The client proceeds with the cvs
protocol itself.
</p>
</dd>
<dt><code class="code">I HATE YOU</code></dt>
<dd><p>The authentication fails. After sending this response, the server may
close the connection. It is up to the server to decide whether to give
this response, which is generic, or a more specific response using
‘<samp class="samp">E</samp>’ and/or ‘<samp class="samp">error</samp>’.
</p>
</dd>
<dt><code class="code">E <var class="var">text</var></code></dt>
<dd><p>Provide a message for the user. After this reponse, the authentication
protocol continues with another response. Typically the server will
provide a series of ‘<samp class="samp">E</samp>’ responses followed by ‘<samp class="samp">error</samp>’.
Compatibility note: <small class="sc">CVS</small> 1.9.10 and older clients will print
<code class="code">unrecognized auth response</code> and <var class="var">text</var>, and then exit, upon
receiving this response.
</p>
</dd>
<dt><code class="code">error <var class="var">code</var> <var class="var">text</var></code></dt>
<dd><p>The authentication fails. After sending this response, the server may
close the connection. The <var class="var">code</var> is a code describing why it
failed, intended for computer consumption. The only code currently
defined is ‘<samp class="samp">0</samp>’ which is nonspecific, but clients must silently
treat any unrecognised codes as nonspecific.
The <var class="var">text</var> should be supplied to the
user. Compatibility note: <small class="sc">CVS</small> 1.9.10 and older clients will print
<code class="code">unrecognized auth response</code> and <var class="var">text</var>, and then exit, upon
receiving this response.
Note that <var class="var">text</var> for this response, or the <var class="var">text</var> in an <code class="code">E</code>
response, is not designed for machine parsing. More vigorous use of
<var class="var">code</var>, or future extensions, will be needed to prove a cleaner
machine-parseable indication of what the error was.
</p></dd>
</dl>
<p>If the client wishes to merely authenticate without starting the cvs
protocol, the procedure is the same, except BEGIN AUTH REQUEST is
replaced with BEGIN VERIFICATION REQUEST, END AUTH REQUEST
is replaced with END VERIFICATION REQUEST, and upon receipt of
I LOVE YOU the connection is closed rather than continuing.
</p>
<p>Another mechanism is GSSAPI authentication. GSSAPI is a
generic interface to security services such as kerberos. GSSAPI is
specified in RFC2078 (GSSAPI version 2) and RFC1508 (GSSAPI version 1);
we are not aware of differences between the two which affect the
protocol in incompatible ways, so we make no attempt to specify one
version or the other.
The procedure here is to start with ‘<samp class="samp">BEGIN
GSSAPI REQUEST</samp>’. GSSAPI authentication information is then exchanged
between the client and the server. Each packet of information consists
of a two byte big endian length, followed by that many bytes of data.
After the GSSAPI authentication is complete, the server continues with
the responses described above (‘<samp class="samp">I LOVE YOU</samp>’, etc.).
</p>
</dd>
<dt>future possibilities</dt>
<dd><p>There are a nearly unlimited number of ways to connect and authenticate.
One might want to allow access based on IP address (similar to the usual
rsh protocol but with different/no restrictions on ports < 1024), to
adopt mechanisms such as Pluggable Authentication Modules (PAM), to
allow users to run their own servers under their own usernames without
root access, or any number of other possibilities. The way to add
future mechanisms, for the most part, should be to continue to use port
2401, but to use different strings in place of ‘<samp class="samp">BEGIN AUTH
REQUEST</samp>’.
</p></dd>
</dl>
<hr>
</div>
<div class="chapter-level-extent" id="Password-scrambling">
<div class="nav-panel">
<p>
Next: <a href="#Protocol" accesskey="n" rel="next">The CVS client/server protocol</a>, Previous: <a href="#Connection-and-Authentication" accesskey="p" rel="prev">How to Connect to and Authenticate Oneself to the CVS server</a>, Up: <a href="#Top" accesskey="u" rel="up">CVS Client/Server</a> </p>
</div>
<h2 class="chapter" id="Password-scrambling-algorithm"><span>4 Password scrambling algorithm<a class="copiable-link" href="#Password-scrambling-algorithm"> ¶</a></span></h2>
<p>The pserver authentication protocol, as described in <a class="ref" href="#Connection-and-Authentication">How to Connect to and Authenticate Oneself to the CVS server</a>, trivially encodes the passwords. This is only to
prevent inadvertent compromise; it provides no protection against even a
relatively unsophisticated attacker. For comparison, HTTP Basic
Authentication (as described in RFC2068) uses BASE64 for a similar
purpose. CVS uses its own algorithm, described here.
</p>
<p>The scrambled password starts with ‘<samp class="samp">A</samp>’, which serves to identify
the scrambling algorithm in use. After that follows a single octet for
each character in the password, according to a fixed encoding. The
values are shown here, with the encoded values in decimal. Control
characters, space, and characters outside the invariant ISO 646
character set are not shown; such characters are not recommended for use
in passwords. There is a long discussion of character set issues in
<a class="ref" href="#Protocol-Notes">Notes on the Protocol</a>.
</p>
<div class="example">
<pre class="example-preformatted"> 0 111 P 125 p 58
! 120 1 52 A 57 Q 55 a 121 q 113
" 53 2 75 B 83 R 54 b 117 r 32
3 119 C 43 S 66 c 104 s 90
4 49 D 46 T 124 d 101 t 44
% 109 5 34 E 102 U 126 e 100 u 98
& 72 6 82 F 40 V 59 f 69 v 60
' 108 7 81 G 89 W 47 g 73 w 51
( 70 8 95 H 38 X 92 h 99 x 33
) 64 9 65 I 103 Y 71 i 63 y 97
* 76 : 112 J 45 Z 115 j 94 z 62
+ 67 ; 86 K 50 k 93
, 116 < 118 L 42 l 39
- 74 = 110 M 123 m 37
. 68 > 122 N 91 n 61
/ 87 ? 105 O 35 _ 56 o 48
</pre></div>
<hr>
</div>
<div class="chapter-level-extent" id="Protocol">
<div class="nav-panel">
<p>
Next: <a href="#Protocol-Notes" accesskey="n" rel="next">Notes on the Protocol</a>, Previous: <a href="#Password-scrambling" accesskey="p" rel="prev">Password scrambling algorithm</a>, Up: <a href="#Top" accesskey="u" rel="up">CVS Client/Server</a> </p>
</div>
<h2 class="chapter" id="The-CVS-client_002fserver-protocol"><span>5 The CVS client/server protocol<a class="copiable-link" href="#The-CVS-client_002fserver-protocol"> ¶</a></span></h2>
<p>In the following, ‘<samp class="samp">\n</samp>’ refers to a linefeed and ‘<samp class="samp">\t</samp>’ refers to
a horizontal tab; <em class="dfn">requests</em> are what the client sends and
<em class="dfn">responses</em> are what the server sends. In general, the connection is
governed by the client—the server does not send responses without
first receiving requests to do so; see <a class="ref" href="#Response-intro">Introduction to Responses</a> for more
details of this convention.
</p>
<p>It is typical, early in the connection, for the client to transmit a
<code class="code">Valid-responses</code> request, containing all the responses it
supports, followed by a <code class="code">valid-requests</code> request, which elicits
from the server a <code class="code">Valid-requests</code> response containing all the
requests it understands. In this way, the client and server each find
out what the other supports before exchanging large amounts of data
(such as file contents).
</p>
<ul class="mini-toc">
<li><a href="#Entries-Lines" accesskey="1">Entries Lines</a></li>
<li><a href="#File-Modes" accesskey="2">File Modes</a></li>
<li><a href="#Filenames" accesskey="3">Conventions regarding transmission of file names</a></li>
<li><a href="#File-transmissions" accesskey="4">File transmissions</a></li>
<li><a href="#Strings" accesskey="5">Strings</a></li>
<li><a href="#Dates" accesskey="6">Dates</a></li>
<li><a href="#Request-intro" accesskey="7">Request intro</a></li>
<li><a href="#Requests" accesskey="8">Requests</a></li>
<li><a href="#Response-intro" accesskey="9">Introduction to Responses</a></li>
<li><a href="#Response-pathnames">The "pathname" in responses</a></li>
<li><a href="#Responses">Responses</a></li>
<li><a href="#Text-tags">Tags for the MT tagged text response</a></li>
<li><a href="#Example">Example</a></li>
<li><a href="#Requirements">Required versus optional parts of the protocol</a></li>
<li><a href="#Obsolete">Obsolete protocol elements</a></li>
</ul>
<hr>
<div class="section-level-extent" id="Entries-Lines">
<div class="nav-panel">
<p>
Next: <a href="#File-Modes" accesskey="n" rel="next">File Modes</a>, Up: <a href="#Protocol" accesskey="u" rel="up">The CVS client/server protocol</a> </p>
</div>
<h3 class="section" id="Entries-Lines-1"><span>5.1 Entries Lines<a class="copiable-link" href="#Entries-Lines-1"> ¶</a></span></h3>
<p>Entries lines are transmitted as:
</p>
<div class="example">
<pre class="example-preformatted">/ <var class="var">name</var> / <var class="var">version</var> / <var class="var">conflict</var> / <var class="var">options</var> / <var class="var">tag_or_date</var>
</pre></div>
<p><var class="var">tag_or_date</var> is either ‘<samp class="samp">T</samp>’ <var class="var">tag</var> or ‘<samp class="samp">D</samp>’ <var class="var">date</var>
or empty. If it is followed by a slash, anything after the slash
shall be silently ignored.
</p>
<p><var class="var">version</var> can be empty, or start with ‘<samp class="samp">0</samp>’ or ‘<samp class="samp">-</samp>’, for no
user file, new user file, or user file to be removed, respectively.
</p>
<p><var class="var">conflict</var>, if it starts with ‘<samp class="samp">+</samp>’, indicates that the file had
conflicts in it. The rest of <var class="var">conflict</var> is ‘<samp class="samp">=</samp>’ if the
timestamp matches the file, or anything else if it doesn’t. If
<var class="var">conflict</var> does not start with a ‘<samp class="samp">+</samp>’, it is silently ignored.
</p>
<p><var class="var">options</var> signifies the keyword expansion options (for example
‘<samp class="samp">-ko</samp>’). In an <code class="code">Entry</code> request, this indicates the options
that were specified with the file from the previous file updating
response (see <a class="pxref" href="#Response-intro">Introduction to Responses</a>, for a list of file updating
responses); if the client is specifying the ‘<samp class="samp">-k</samp>’ or ‘<samp class="samp">-A</samp>’
option to <code class="code">update</code>, then it is the server which figures out what
overrides what.
</p>
<hr>
</div>
<div class="section-level-extent" id="File-Modes">
<div class="nav-panel">
<p>
Next: <a href="#Filenames" accesskey="n" rel="next">Conventions regarding transmission of file names</a>, Previous: <a href="#Entries-Lines" accesskey="p" rel="prev">Entries Lines</a>, Up: <a href="#Protocol" accesskey="u" rel="up">The CVS client/server protocol</a> </p>
</div>
<h3 class="section" id="File-Modes-1"><span>5.2 File Modes<a class="copiable-link" href="#File-Modes-1"> ¶</a></span></h3>
<p>A mode is any number of repetitions of
</p>
<div class="example">
<pre class="example-preformatted"><var class="var">mode-type</var> = <var class="var">data</var>
</pre></div>
<p>separated by ‘<samp class="samp">,</samp>’.
</p>
<p><var class="var">mode-type</var> is an identifier composed of alphanumeric characters.
Currently specified: ‘<samp class="samp">u</samp>’ for user, ‘<samp class="samp">g</samp>’ for group, ‘<samp class="samp">o</samp>’
for other (see below for discussion of whether these have their POSIX
meaning or are more loose). Unrecognised values of <var class="var">mode-type</var>
are silently ignored.
</p>
<p><var class="var">data</var> consists of any data not containing ‘<samp class="samp">,</samp>’, ‘<samp class="samp">\0</samp>’ or
‘<samp class="samp">\n</samp>’. For ‘<samp class="samp">u</samp>’, ‘<samp class="samp">g</samp>’, and ‘<samp class="samp">o</samp>’ mode types, data
consists of alphanumeric characters, where ‘<samp class="samp">r</samp>’ means read, ‘<samp class="samp">w</samp>’
means write, ‘<samp class="samp">x</samp>’ means execute, and unrecognised letters are
silently ignored.
</p>
<p>The two most obvious ways in which the mode matters are: (1) is it
writeable? This is used by the developer communication features, and
is implemented even on OS/2 (and could be implemented on DOS), whose
notion of mode is limited to a readonly bit. (2) is it executable?
Unix CVS users need CVS to store this setting (for shell scripts and
the like). The current CVS implementation on unix does a little bit
more than just maintain these two settings, but it doesn’t really have
a nice general facility to store or version control the mode, even on
unix, much less across operating systems with diverse protection
features. So all the ins and outs of what the mode means across
operating systems haven’t really been worked out (e.g. should the VMS
port use ACLs to get POSIX semantics for groups?).
</p>
<hr>
</div>
<div class="section-level-extent" id="Filenames">
<div class="nav-panel">
<p>
Next: <a href="#File-transmissions" accesskey="n" rel="next">File transmissions</a>, Previous: <a href="#File-Modes" accesskey="p" rel="prev">File Modes</a>, Up: <a href="#Protocol" accesskey="u" rel="up">The CVS client/server protocol</a> </p>
</div>
<h3 class="section" id="Conventions-regarding-transmission-of-file-names"><span>5.3 Conventions regarding transmission of file names<a class="copiable-link" href="#Conventions-regarding-transmission-of-file-names"> ¶</a></span></h3>
<p>In most contexts, ‘<samp class="samp">/</samp>’ is used to separate directory and file
names in filenames, and any use of other conventions (for example,
that the user might type on the command line) is converted to that
form. The only exceptions might be a few cases in which the server
provides a magic cookie which the client then repeats verbatim, but as
the server has not yet been ported beyond unix, the two rules provide
the same answer (and what to do if future server ports are operating
on a repository like e:/foo or CVS_ROOT:[FOO.BAR] has not been
carefully thought out).
</p>
<p>Characters outside the invariant ISO 646 character set should be avoided
in filenames. This restriction may need to be relaxed to allow for
characters such as ‘<samp class="samp">[</samp>’ and ‘<samp class="samp">]</samp>’ (see above about non-unix
servers); this has not been carefully considered (and currently
implementations probably use whatever character sets that the operating
systems they are running on allow, and/or that users specify). Of
course the most portable practice is to restrict oneself further, to the
POSIX portable filename character set as specified in POSIX.1.
</p>
<hr>
</div>
<div class="section-level-extent" id="File-transmissions">
<div class="nav-panel">
<p>
Next: <a href="#Strings" accesskey="n" rel="next">Strings</a>, Previous: <a href="#Filenames" accesskey="p" rel="prev">Conventions regarding transmission of file names</a>, Up: <a href="#Protocol" accesskey="u" rel="up">The CVS client/server protocol</a> </p>
</div>
<h3 class="section" id="File-transmissions-1"><span>5.4 File transmissions<a class="copiable-link" href="#File-transmissions-1"> ¶</a></span></h3>
<p>File contents (noted below as <var class="var">file transmission</var>) can be sent in
one of two forms. The simpler form is a number of bytes, followed by a
linefeed, followed by the specified number of bytes of file contents.
These are the entire contents of the specified file. Second, if both
client and server support ‘<samp class="samp">gzip-file-contents</samp>’, a ‘<samp class="samp">z</samp>’ may
precede the length, and the ‘file contents’ sent are actually compressed
with ‘<samp class="samp">gzip</samp>’ (RFC1952/1951) compression. The length specified is
that of the compressed version of the file.
</p>
<p>In neither case are the file content followed by any additional data.
The transmission of a file will end with a linefeed iff that file (or its
compressed form) ends with a linefeed.
</p>
<p>The encoding of file contents depends on the value for the ‘<samp class="samp">-k</samp>’
option. If the file is binary (as specified by the ‘<samp class="samp">-kb</samp>’ option in
the appropriate place), then it is just a certain number of octets, and
the protocol contributes nothing towards determining the encoding (using
the file name is one widespread, if not universally popular, mechanism).
If the file is text (not binary), then the file is sent as a series of
lines, separated by linefeeds. If the keyword expansion is set to
something other than ‘<samp class="samp">-ko</samp>’, then it is expected that the file
conform to the RCS expectations regarding keyword expansion—in
particular, that it is in a character set such as ASCII in which 0x24 is
a dollar sign (‘<samp class="samp">$</samp>’).
</p>
<hr>
</div>
<div class="section-level-extent" id="Strings">
<div class="nav-panel">
<p>
Next: <a href="#Dates" accesskey="n" rel="next">Dates</a>, Previous: <a href="#File-transmissions" accesskey="p" rel="prev">File transmissions</a>, Up: <a href="#Protocol" accesskey="u" rel="up">The CVS client/server protocol</a> </p>
</div>
<h3 class="section" id="Strings-1"><span>5.5 Strings<a class="copiable-link" href="#Strings-1"> ¶</a></span></h3>
<p>In various contexts, for example the <code class="code">Argument</code> request and the
<code class="code">M</code> response, one transmits what is essentially an arbitrary
string. Often this will have been supplied by the user (for example,
the ‘<samp class="samp">-m</samp>’ option to the <code class="code">ci</code> request will show up in the
<code class="code">LOGM</code> response). The protocol has no mechanism to specify the
character set of such strings; it would have been, initially, fairly
safe to stick to the invariant ISO 646 character set but the existing
practice is probably to just transmit whatever the user specifies,
and hope that everyone involved agrees which character set is in use,
or sticks to a common subset. In modern times, UTF-8 should be used.
</p>
<hr>
</div>
<div class="section-level-extent" id="Dates">
<div class="nav-panel">
<p>
Next: <a href="#Request-intro" accesskey="n" rel="next">Request intro</a>, Previous: <a href="#Strings" accesskey="p" rel="prev">Strings</a>, Up: <a href="#Protocol" accesskey="u" rel="up">The CVS client/server protocol</a> </p>
</div>
<h3 class="section" id="Dates-1"><span>5.6 Dates<a class="copiable-link" href="#Dates-1"> ¶</a></span></h3>
<p>The protocol contains times and dates in various places.
</p>
<p>For the ‘<samp class="samp">-D</samp>’ option to the <code class="code">annotate</code>, <code class="code">co</code>, <code class="code">diff</code>,
<code class="code">export</code>, <code class="code">history</code>, <code class="code">rannotate</code>, <code class="code">rdiff</code>,
<code class="code">rtag</code>, <code class="code">tag</code>,
and <code class="code">update</code> requests, the server should support two formats:
</p>
<div class="example">
<pre class="example-preformatted">26 May 1997 13:01:40 -0000 ; <span class="r">RFC 822 as modified by RFC 1123</span>
5/26/1997 13:01:40 GMT ; <span class="r">traditional</span>
</pre></div>
<p>The former format is preferred; the latter however is sent by the CVS
command line client (versions 1.5 through at least 1.9).
</p>
<p>For the ‘<samp class="samp">-d</samp>’ option to the <code class="code">log</code> and <code class="code">rlog</code> requests,
servers should at
least support RFC 822/1123 format. Clients are encouraged to use this
format too (the command line CVS client, version 1.10 and older, just passed
along the date format specified by the user, however).
</p>
<p>The <code class="code">Mod-time</code> response and <code class="code">Checkin-time</code> request use RFC
822/1123 format (see the descriptions of that response and request for
details).
</p>
<p>For <code class="code">Notify</code>, see the description of that request.
</p>
<hr>
</div>
<div class="section-level-extent" id="Request-intro">
<div class="nav-panel">
<p>
Next: <a href="#Requests" accesskey="n" rel="next">Requests</a>, Previous: <a href="#Dates" accesskey="p" rel="prev">Dates</a>, Up: <a href="#Protocol" accesskey="u" rel="up">The CVS client/server protocol</a> </p>
</div>
<h3 class="section" id="Request-intro-1"><span>5.7 Request intro<a class="copiable-link" href="#Request-intro-1"> ¶</a></span></h3>
<p>By convention, requests which begin with a capital letter do not elicit
a response from the server, while all others do – save one. The
exception is ‘<samp class="samp">gzip-file-contents</samp>’. Unrecognised requests will
always elicit a response from the server, even if that request begins
with a capital letter.
</p>
<p>The term <em class="dfn">command</em> means a request which expects a response (except
<code class="code">valid-requests</code>). The general model is that the client transmits
a great number of requests, but nothing happens until the very end when
the client transmits a command. Although the intention is that
transmitting several commands in one connection should be legal,
existing servers probably have some bugs with some combinations of more
than one command, and so clients may find it necessary to make several
connections in some cases. This should be thought of as a workaround
rather than a desired attribute of the protocol.
</p>
<hr>
</div>
<div class="section-level-extent" id="Requests">
<div class="nav-panel">
<p>
Next: <a href="#Response-intro" accesskey="n" rel="next">Introduction to Responses</a>, Previous: <a href="#Request-intro" accesskey="p" rel="prev">Request intro</a>, Up: <a href="#Protocol" accesskey="u" rel="up">The CVS client/server protocol</a> </p>
</div>
<h3 class="section" id="Requests-1"><span>5.8 Requests<a class="copiable-link" href="#Requests-1"> ¶</a></span></h3>
<p>Here are the requests:
</p>
<dl class="table">
<dt><code class="code">Root <var class="var">pathname</var> \n</code></dt>
<dd><p>Response expected: no. Tell the server which <code class="code">CVSROOT</code> to use.
Note that <var class="var">pathname</var> is a local directory and <em class="emph">not</em> a fully
qualified <code class="code">CVSROOT</code> variable. <var class="var">pathname</var> must
already exist; if creating a new root, use the <code class="code">init</code> request, not
<code class="code">Root</code>. <var class="var">pathname</var> does not include the hostname of the
server, how to access the server, etc.; by the time the CVS protocol is
in use, connection, authentication, etc., are already taken care of.
</p>
<p>The <code class="code">Root</code> request must be sent only once, and it must be sent
before any requests other than <code class="code">Valid-responses</code>,
<code class="code">valid-requests</code>, <code class="code">UseUnchanged</code>, <code class="code">Set</code>,
<code class="code">Global_option</code>, <code class="code">init</code>, <code class="code">noop</code>, or <code class="code">version</code>.
</p>
</dd>
<dt><code class="code">Valid-responses <var class="var">request-list</var> \n</code></dt>
<dd><p>Response expected: no.
Tell the server what responses the client will accept.
request-list is a space separated list of tokens.
The <code class="code">Root</code> request need not have been previously sent.
</p>
</dd>
<dt><code class="code">valid-requests \n</code></dt>
<dd><p>Response expected: yes.
Ask the server to send back a <code class="code">Valid-requests</code> response.
The <code class="code">Root</code> request need not have been previously sent.
</p>
</dd>
<dt><code class="code">Command-prep <var class="var">command</var> \n</code></dt>
<dd><p>Response expected: yes.
Notify the server of the command that we are leading up to. Intended to allow
the server to send a redirect for write operations. Requires either an
<code class="code">ok</code> or <code class="code">Redirect</code> respnose.
</p>
</dd>
<dt><code class="code">Referrer <var class="var">CVSROOT</var> \n</code></dt>
<dd><p>Response expected: no.
Notify a primary server of a server which referred us. Intended to allow
a primary (write) server to update the read-only mirror a client is using
for reads to minimise races on any subsequent updates from the client.
</p>
</dd>
<dt><code class="code">Directory <var class="var">local-directory</var> \n</code></dt>
<dt><code class="code">Relative-directory <var class="var">local-directory</var> \n</code></dt>
<dd><p>Additional data: <var class="var">repository</var> \n. Response expected: no.
Tell the server what directory to use.
</p>
<p>The <var class="var">repository</var> should be a directory name from a previous server
response and may be specified either relative to the <var class="var">pathname</var> provided
with the <code class="code">Root</code> request or absolute. Relative or absolute, it must
specify a path within <var class="var">pathname</var>.
</p>
<p>Prior to <small class="sc">CVS</small> version <strong class="strong">FIXME - release number 1.12.10?</strong>,
<var class="var">repository</var> had to be absolute and <code class="code">Relative-directory</code> was not a
valid request. The <code class="code">Relative-directory</code> request is synonymous with
<code class="code">Directory</code> and is provided to alert modern clients that a relative
<var class="var">repository</var> is acceptable.
</p>
<p>Note that this both gives a default for <code class="code">Entry</code> and <code class="code">Modified</code> and
also for <code class="code">ci</code> and the other commands; normal usage is to send
<code class="code">Directory</code> for each directory in which there will be an
<code class="code">Entry</code> or <code class="code">Modified</code>, and then a final <code class="code">Directory</code>
for the original directory, then the command.
The <var class="var">local-directory</var> is relative to
the top level at which the command is occurring (i.e. the last
<code class="code">Directory</code> which is sent before the command);
to indicate that top level, ‘<samp class="samp">.</samp>’ should be sent for
<var class="var">local-directory</var>.
</p>
<p>Here is an example of where a client gets <var class="var">repository</var> and
<var class="var">local-directory</var>. Suppose that there is a module defined by
</p>
<div class="example">
<pre class="example-preformatted">moddir 1dir
</pre></div>
<p>That is, one can check out <code class="code">moddir</code> and it will take <code class="code">1dir</code> in
the repository and check it out to <code class="code">moddir</code> in the working
directory. Then an initial check out could proceed like this:
</p>
<div class="example">
<pre class="example-preformatted">C: Root /home/kingdon/zwork/cvsroot
. . .
C: Argument moddir
C: Directory .
C: .
C: co
S: Clear-sticky moddir/
S: 1dir/
. . .
S: ok
</pre></div>
<p>In this example the response shown is <code class="code">Clear-sticky</code>, but it could
be another response instead. Note that it returns two pathnames.
The first one, <samp class="file">moddir/</samp>, indicates the working
directory to check out into. The second one, ending in <samp class="file">1dir/</samp>,
indicates the directory to pass back to the server in a subsequent
<code class="code">Directory</code> request. For example, a subsequent <code class="code">update</code>
request might look like:
</p>
<div class="example">
<pre class="example-preformatted">C: Directory moddir
C: 1dir
. . .
C: update
</pre></div>
<p>For a given <var class="var">local-directory</var>, the repository will be the same for
each of the responses, so one can use the repository from whichever
response is most convenient. Typically a client will store the
repository along with the sources for each <var class="var">local-directory</var>, use
that same setting whenever operating on that <var class="var">local-directory</var>, and
not update the setting as long as the <var class="var">local-directory</var> exists.
</p>
<p>A client is free to rename a <var class="var">local-directory</var> at any time (for
example, in response to an explicit user request). While it is true
that the server supplies a <var class="var">local-directory</var> to the client, as noted
above, this is only the default place to put the directory. Of course,
the various <code class="code">Directory</code> requests for a single command (for example,
<code class="code">update</code> or <code class="code">ci</code> request) should name a particular directory
with the same <var class="var">local-directory</var>.
</p>
<p>Each <code class="code">Directory</code> request specifies a brand-new
<var class="var">local-directory</var> and <var class="var">repository</var>; that is,
<var class="var">local-directory</var> and <var class="var">repository</var> are never relative to paths
specified in any previous <code class="code">Directory</code> request.
</p>
<p>Here’s a more complex example, in which we request an update of a
working directory which has been checked out from multiple places in the
repository.
</p>
<div class="example">
<pre class="example-preformatted">C: Argument dir1
C: Directory dir1
C: mod1
. . .
C: Argument dir2
C: Directory dir2
C: mod2
. . .
C: Argument dir3
C: Directory dir3/subdir3
C: mod3
. . .
C: update
</pre></div>
<p>While directories <code class="code">dir1</code> and <code class="code">dir2</code> will be handled in similar
fashion to the other examples given above, <code class="code">dir3</code> is slightly
different from the server’s standpoint. Notice that module <code class="code">mod3</code>
is actually checked out into <code class="code">dir3/subdir3</code>, meaning that directory
<code class="code">dir3</code> is either empty or does not contain data checked out from
this repository.
</p>
<p>The above example will work correctly in <small class="sc">CVS</small> 1.10.1 and later. The
server will descend the tree starting from all directories mentioned in
<code class="code">Argument</code> requests and update those directories specifically
mentioned in <code class="code">Directory</code> requests.
</p>
<p>Previous versions of <small class="sc">CVS</small> (1.10 and earlier) do not behave the same
way. While the descent of the tree begins at all directories mentioned
in <code class="code">Argument</code> requests, descent into subdirectories only occurs if
a directory has been mentioned in a <code class="code">Directory</code> request.
Therefore, the above example would succeed in updating <code class="code">dir1</code> and
<code class="code">dir2</code>, but would skip <code class="code">dir3</code> because that directory was not
specifically mentioned in a <code class="code">Directory</code> request. A functional
version of the above that would run on a 1.10 or earlier server is as
follows:
</p>
<div class="example">
<pre class="example-preformatted">C: Argument dir1
C: Directory dir1
C: mod1
. . .
C: Argument dir2
C: Directory dir2
C: mod2
. . .
C: Argument dir3
C: Directory dir3
C: .
. . .
C: Directory dir3/subdir3
C: mod3
. . .
C: update
</pre></div>
<p>Note the extra <code class="code">Directory dir3</code> request. It might be better to use
<code class="code">Emptydir</code> as the repository for the <code class="code">dir3</code> directory, but the
above will certainly work.
</p>
<p>One more peculiarity of the 1.10 and earlier protocol is the ordering of
<code class="code">Directory</code> arguments. In order for a subdirectory to be
registered correctly for descent by the recursion processor, its parent
must be sent first. For example, the following would not work to update
<code class="code">dir3/subdir3</code>:
</p>
<div class="example">
<pre class="example-preformatted">. . .
C: Argument dir3
C: Directory dir3/subdir3
C: mod3
. . .
C: Directory dir3
C: .
. . .
C: update
</pre></div>
<p>The implementation of the server in 1.10 and earlier writes the
administration files for a given directory at the time of the
<code class="code">Directory</code> request. It also tries to register the directory with
its parent to mark it for recursion. In the above example, at the time
<code class="code">dir3/subdir3</code> is created, the physical directory for <code class="code">dir3</code>
will be created on disk, but the administration files will not have been
created. Therefore, when the server tries to register
<code class="code">dir3/subdir3</code> for recursion, the operation will silently fail
because the administration files do not yet exist for <code class="code">dir3</code>.
</p>
</dd>
<dt><code class="code">Max-dotdot <var class="var">level</var> \n</code></dt>
<dd><p>Response expected: no.
Tell the server that <var class="var">level</var> levels of directories above the
directory which <code class="code">Directory</code> requests are relative to will be
needed. For example, if the client is planning to use a
<code class="code">Directory</code> request for <samp class="file">../../foo</samp>, it must send a
<code class="code">Max-dotdot</code> request with a <var class="var">level</var> of at least 2.
<code class="code">Max-dotdot</code> must be sent before the first <code class="code">Directory</code>
request.
</p>
</dd>
<dt><code class="code">Static-directory \n</code></dt>
<dd><p>Response expected: no. Tell the server that the directory most recently
specified with <code class="code">Directory</code> should not have
additional files checked out unless explicitly requested. The client
sends this if the <code class="code">Entries.Static</code> flag is set, which is controlled
by the <code class="code">Set-static-directory</code> and <code class="code">Clear-static-directory</code>
responses.
</p>
</dd>
<dt><code class="code">Sticky <var class="var">tagspec</var> \n</code></dt>
<dd><p>Response expected: no. Tell the server that the directory most recently
specified with <code class="code">Directory</code> has a sticky tag or date <var class="var">tagspec</var>.
The first character of <var class="var">tagspec</var> is ‘<samp class="samp">T</samp>’ for a tag, ‘<samp class="samp">D</samp>’
for a date, or some other character supplied by a Set-sticky response
from a previous request to the server. The remainder of <var class="var">tagspec</var>
contains the actual tag or date, again as supplied by Set-sticky.
</p>
<p>The server should remember <code class="code">Static-directory</code> and <code class="code">Sticky</code>
requests for a particular directory; the client need not resend them
each time it sends a <code class="code">Directory</code> request for a given directory.
However, the server is not obliged to remember them beyond the context
of a single command.
</p>
</dd>
<dt><code class="code">Checkin-prog <var class="var">program</var> \n</code></dt>
<dd><p>Response expected: no. Tell the server that the directory most recently
specified with <code class="code">Directory</code> has a checkin program <var class="var">program</var>.
Such a program would have been previously set with the
<code class="code">Set-checkin-prog</code> response.
</p>
</dd>
<dt><code class="code">Update-prog <var class="var">program</var> \n</code></dt>
<dd><p>Response expected: no. Tell the server that the directory most recently
specified with <code class="code">Directory</code> has an update program <var class="var">program</var>.
Such a program would have been previously set with the
<code class="code">Set-update-prog</code> response.
</p>
</dd>
<dt><code class="code">Entry <var class="var">entry-line</var> \n</code></dt>
<dd><p>Response expected: no. Tell the server what version of a file is on the
local machine. The name in <var class="var">entry-line</var> is a name relative to the
directory most recently specified with <code class="code">Directory</code>. If the user
is operating on only some files in a directory, <code class="code">Entry</code> requests
for only those files need be included. If an <code class="code">Entry</code> request is
sent without <code class="code">Modified</code>, <code class="code">Is-modified</code>, or <code class="code">Unchanged</code>,
it means the file is
lost (does not exist in the working directory). If both <code class="code">Entry</code>
and one of <code class="code">Modified</code>, <code class="code">Is-modified</code>, or <code class="code">Unchanged</code> are
sent for the same file, <code class="code">Entry</code> must be sent first. For a
given file, one can send <code class="code">Modified</code>, <code class="code">Is-modified</code>, or
<code class="code">Unchanged</code>, but not more than one of these three.
</p>
</dd>
<dt><code class="code">Kopt <var class="var">option</var> \n</code></dt>
<dd><p>This indicates to the server which keyword expansion options to use for
the file specified by the next <code class="code">Modified</code> or <code class="code">Is-modified</code>
request (for example ‘<samp class="samp">-kb</samp>’ for a binary file). This is similar to
<code class="code">Entry</code>, but is used for a file for which there is no entries line.
Typically this will be a file being added via an <code class="code">add</code> or
<code class="code">import</code> request. The client may not send both <code class="code">Kopt</code> and
<code class="code">Entry</code> for the same file.
</p>
</dd>
<dt><code class="code">Checkin-time <var class="var">time</var> \n</code></dt>
<dd><p>For the file specified by the next <code class="code">Modified</code> request, use
<var class="var">time</var> as the time of the checkin. The <var class="var">time</var> is in the format
specified by RFC822 as modified by RFC1123. The client may specify any
timezone it chooses; servers will want to convert that to their own
timezone as appropriate. An example of this format is:
</p>
<div class="example">
<pre class="example-preformatted">26 May 1997 13:01:40 -0400
</pre></div>
<p>There is no requirement that the client and server clocks be
synchronised. The client just sends its recommendation for a timestamp
(based on file timestamps or whatever), and the server should just believe
it (this means that the time might be in the future, for example).
</p>
<p>Note that this is not a general-purpose way to tell the server about the
timestamp of a file; that would be a separate request (if there are
servers which can maintain timestamp and time of checkin separately).
</p>
<p>This request should affect the <code class="code">import</code> request, and may optionally
affect the <code class="code">ci</code> request or other relevant requests if any.
</p>
</dd>
<dt><code class="code">Modified <var class="var">filename</var> \n</code></dt>
<dd><p>Response expected: no. Additional data: mode, \n, file transmission.
Send the server a copy of one locally modified file. <var class="var">filename</var> is
a file within the most recent directory sent with <code class="code">Directory</code>; it
must not contain ‘<samp class="samp">/</samp>’. If
the user is operating on only some files in a directory, only those
files need to be included. This can also be sent without <code class="code">Entry</code>,
if there is no entry for the file.
</p>
</dd>
<dt><code class="code">Is-modified <var class="var">filename</var> \n</code></dt>
<dd><p>Response expected: no. Additional data: none. Like <code class="code">Modified</code>,
but used if the server only needs
to know whether the file is modified, not the contents.
</p>
<p>The commands which can take <code class="code">Is-modified</code> instead of
<code class="code">Modified</code> with no known change in behavior are: <code class="code">admin</code>,
<code class="code">diff</code> (if and only if two ‘<samp class="samp">-r</samp>’ or ‘<samp class="samp">-D</samp>’ options are
specified), <code class="code">watch-on</code>, <code class="code">watch-off</code>, <code class="code">watch-add</code>,
<code class="code">watch-remove</code>, <code class="code">watchers</code>, <code class="code">editors</code>,
<code class="code">log</code>, and <code class="code">annotate</code>.
</p>
<p>For the <code class="code">status</code> command, one can send <code class="code">Is-modified</code> but if
the client is using imperfect mechanisms such as timestamps to determine
whether to consider a file modified, then the behavior will be
different. That is, if one sends <code class="code">Modified</code>, then the server will
actually compare the contents of the file sent and the one it derives
from to determine whether the file is genuinely modified. But if one
sends <code class="code">Is-modified</code>, then the server takes the client’s word for
it. A similar situation exists for <code class="code">tag</code>, if the ‘<samp class="samp">-c</samp>’ option
is specified.
</p>
<p>Commands for which <code class="code">Modified</code> is necessary are <code class="code">co</code>,
<code class="code">ci</code>, <code class="code">update</code>, and <code class="code">import</code>.
</p>
<p>Commands which do not need to inform the server about a working
directory, and thus should not be sending either <code class="code">Modified</code> or
<code class="code">Is-modified</code>: <code class="code">rdiff</code>, <code class="code">rtag</code>, <code class="code">history</code>,
<code class="code">init</code>, and <code class="code">release</code>.
</p>
<p>Commands for which further investigation is warranted are:
<code class="code">remove</code>, <code class="code">add</code>, and <code class="code">export</code>. Pending such
investigation, the more conservative course of action is to stick to
<code class="code">Modified</code>.
</p>
</dd>
<dt><code class="code">Unchanged <var class="var">filename</var> \n</code></dt>
<dd><p>Response expected: no. Tell the server that <var class="var">filename</var> has not been
modified in the checked out directory. The <var class="var">filename</var> is
a file within the most recent directory sent with <code class="code">Directory</code>; it
must not contain ‘<samp class="samp">/</samp>’.
</p>
</dd>
<dt><code class="code">UseUnchanged \n</code></dt>
<dd><p>Response expected: no. To specify the version of the protocol described
in this document, servers must support this request (although it need
not do anything) and clients must issue it.
The <code class="code">Root</code> request need not have been previously sent.
</p>
</dd>
<dt><code class="code">Notify <var class="var">filename</var> \n</code></dt>
<dd><p>Response expected: no.
Tell the server that an <code class="code">edit</code> or <code class="code">unedit</code> command has taken
place. The server needs to send a <code class="code">Notified</code> response, but such
response is deferred until the next time that the server is sending
responses.
The <var class="var">filename</var> is a file within the most recent directory sent with
<code class="code">Directory</code>; it must not contain ‘<samp class="samp">/</samp>’.
Additional data:
</p><div class="example">
<pre class="example-preformatted"><var class="var">notification-type</var> \t <var class="var">time</var> \t <var class="var">clienthost</var> \t
<var class="var">working-dir</var> \t <var class="var">watches</var> \n
</pre></div>
<p>where <var class="var">notification-type</var> is ‘<samp class="samp">E</samp>’ for edit, ‘<samp class="samp">U</samp>’ for
unedit, undefined behavior if ‘<samp class="samp">C</samp>’, and all other letters should be
silently ignored for future expansion.
<var class="var">time</var> is the time at which the edit or unedit took place, in a
user-readable format of the client’s choice (the server should treat the
time as an opaque string rather than interpreting it).
<var class="var">clienthost</var> is the name of the host on which the edit or unedit
took place, and <var class="var">working-dir</var> is the pathname of the working
directory where the edit or unedit took place. <var class="var">watches</var> are the
temporary watches, zero or more of the following characters in the
following order: ‘<samp class="samp">E</samp>’ for edit, ‘<samp class="samp">U</samp>’ for unedit, ‘<samp class="samp">C</samp>’ for
commit, and all other letters should be silently ignored for future
expansion. If <var class="var">notification-type</var> is ‘<samp class="samp">E</samp>’ the temporary watches
are set; if it is ‘<samp class="samp">U</samp>’ they are cleared.
If <var class="var">watches</var> is followed by \t then the
\t and the rest of the line should be ignored, for future expansion.
</p>
<p>The <var class="var">time</var>, <var class="var">clienthost</var>, and <var class="var">working-dir</var> fields may not
contain the characters ‘<samp class="samp">+</samp>’, ‘<samp class="samp">,</samp>’, ‘<samp class="samp">></samp>’, ‘<samp class="samp">;</samp>’, or ‘<samp class="samp">=</samp>’.
</p>
<p>Note that a client may be capable of performing an <code class="code">edit</code> or
<code class="code">unedit</code> operation without connecting to the server at that time,
and instead connecting to the server when it is convenient (for example,
when a laptop is on the net again) to send the <code class="code">Notify</code> requests.
Even if a client is capable of deferring notifications, it should
attempt to send them immediately (one can send <code class="code">Notify</code> requests
together with a <code class="code">noop</code> request, for example), unless perhaps if
it can know that a connection would be impossible.
</p>
</dd>
<dt><code class="code">Questionable <var class="var">filename</var> \n</code></dt>
<dd><p>Response expected: no. Additional data: no. Tell the server to check
whether <var class="var">filename</var> should be ignored, and if not, next time the
server sends responses, send (in a <code class="code">M</code> response) ‘<samp class="samp">?</samp>’ followed
by the directory and filename. <var class="var">filename</var> must not contain
‘<samp class="samp">/</samp>’; it needs to be a file in the directory named by the most
recent <code class="code">Directory</code> request.
</p>
</dd>
<dt><code class="code">Case \n</code></dt>
<dd><p>Response expected: no. Tell the server that filenames should be matched
in a case-insensitive fashion. Note that this is not the primary
mechanism for achieving case-insensitivity; for the most part the client
keeps track of the case which the server wants to use and takes care to
always use that case regardless of what the user specifies. For example
the filenames given in <code class="code">Entry</code> and <code class="code">Modified</code> requests for the
same file must match in case regardless of whether the <code class="code">Case</code>
request is sent. The latter mechanism is more general (it could also be
used for 8.3 filenames, VMS filenames with more than one ‘<samp class="samp">.</samp>’, and
any other situation in which there is a predictable mapping between
filenames in the working directory and filenames in the protocol), but
there are some situations it cannot handle (ignore patterns, or
situations where the user specifies a filename and the client does not
know about that file).
</p>
<p>Though this request will be supported into the forseeable future, it has been
the source of numerous bug reports in the past due to the complexity of testing
this functionality via the test suite and client developers are encouraged not
to use it. Instead, please consider munging conflicting names and maintaining
a map for communicating with the server. For example, suppose the server sends
files <samp class="file">case</samp>, <samp class="file">CASE</samp>, and <samp class="file">CaSe</samp>. The client could write all
three files to names such as, <samp class="file">case</samp>, <samp class="file">case_prefix_case</samp>, and
<samp class="file">case_prefix_2_case</samp> and maintain a mapping between the file names in, for
instance a new <samp class="file">CVS/Map</samp> file.
</p>
</dd>
<dt><code class="code">Argument <var class="var">text</var> \n</code></dt>
<dd><p>Response expected: no.
Save argument for use in a subsequent command. Arguments
accumulate until an argument-using command is given, at which point
they are forgotten.
</p>
</dd>
<dt><code class="code">Argumentx <var class="var">text</var> \n</code></dt>
<dd><p>Response expected: no. Append \n followed by text to the current
argument being saved.
</p>
</dd>
<dt><code class="code">Global_option <var class="var">option</var> \n</code></dt>
<dd><p>Response expected: no.
Transmit one of the global options ‘<samp class="samp">-q</samp>’, ‘<samp class="samp">-Q</samp>’, ‘<samp class="samp">-l</samp>’,
‘<samp class="samp">-t</samp>’, ‘<samp class="samp">-r</samp>’, or ‘<samp class="samp">-n</samp>’. <var class="var">option</var> must be one of those
strings, no variations (such as combining of options) are allowed. For
graceful handling of <code class="code">valid-requests</code>, it is probably better to
make new global options separate requests, rather than trying to add
them to this request.
The <code class="code">Root</code> request need not have been previously sent.
</p>
</dd>
<dt><code class="code">Gzip-stream <var class="var">level</var> \n</code></dt>
<dd><p>Response expected: no.
Use zlib (RFC 1950/1951) compression to compress all further communication
between the client and the server. As of <small class="sc">CVS</small> 1.12.13, this request needs
to be sent as the first non-rootless request if the server is configured
with compression level restrictions and <var class="var">level</var> is outside the restricted
range. After this request is sent, all further communication must be
compressed. All further data received from the server will also be
compressed. The <var class="var">level</var> argument suggests to the server the level of
compression that it should apply; it should be an integer between 0 and 9,
inclusive, where ‘<samp class="samp">0</samp>’ means no compression and higher numbers indicate more
compression.
</p>
</dd>
<dt><code class="code">Kerberos-encrypt \n</code></dt>
<dd><p>Response expected: no.
Use Kerberos encryption to encrypt all further communication between the
client and the server. This will only work if the connection was made
over Kerberos in the first place. If both the <code class="code">Gzip-stream</code> and
the <code class="code">Kerberos-encrypt</code> requests are used, the
<code class="code">Kerberos-encrypt</code> request should be used first. This will make
the client and server encrypt the compressed data, as opposed to
compressing the encrypted data. Encrypted data is generally
incompressible.
</p>
<p>Note that this request does not fully prevent an attacker from hijacking
the connection, in the sense that it does not prevent hijacking the
connection between the initial authentication and the
<code class="code">Kerberos-encrypt</code> request.
</p>
</dd>
<dt><code class="code">Gssapi-encrypt \n</code></dt>
<dd><p>Response expected: no.
Use GSSAPI encryption to encrypt all further communication between the
client and the server. This will only work if the connection was made
over GSSAPI in the first place. See <code class="code">Kerberos-encrypt</code>, above, for
the relation between <code class="code">Gssapi-encrypt</code> and <code class="code">Gzip-stream</code>.
</p>
<p>Note that this request does not fully prevent an attacker from hijacking
the connection, in the sense that it does not prevent hijacking the
connection between the initial authentication and the
<code class="code">Gssapi-encrypt</code> request.
</p>
</dd>
<dt><code class="code">Gssapi-authenticate \n</code></dt>
<dd><p>Response expected: no.
Use GSSAPI authentication to authenticate all further communication
between the client and the server. This will only work if the
connection was made over GSSAPI in the first place. Encrypted data is
automatically authenticated, so using both <code class="code">Gssapi-authenticate</code>
and <code class="code">Gssapi-encrypt</code> has no effect beyond that of
<code class="code">Gssapi-encrypt</code>. Unlike encrypted data, it is reasonable to
compress authenticated data.
</p>
<p>Note that this request does not fully prevent an attacker from hijacking
the connection, in the sense that it does not prevent hijacking the
connection between the initial authentication and the
<code class="code">Gssapi-authenticate</code> request.
</p>
</dd>
<dt><code class="code">Set <var class="var">variable</var>=<var class="var">value</var> \n</code></dt>
<dd><p>Response expected: no.
Set a user variable <var class="var">variable</var> to <var class="var">value</var>.
The <code class="code">Root</code> request need not have been previously sent.
</p>
</dd>
<dt><code class="code">Hostname <var class="var">hostname</var> \n</code></dt>
<dd><p>Response expected: no. Set the client hostname for an upcoming <code class="code">edit</code>
request.
</p>
</dd>
<dt><code class="code">LocalDir <var class="var">hostname</var> \n</code></dt>
<dd><p>Response expected: no. Set the local client directory name for an upcoming
<code class="code">edit</code> request.
</p>
</dd>
<dt><code class="code">expand-modules \n</code></dt>
<dd><p>Response expected: yes. Expand the modules which are specified in the
arguments. Returns the data in <code class="code">Module-expansion</code> responses. Note
that the server can assume that this is checkout or export, not rtag or
rdiff; the latter do not access the working directory and thus have no
need to expand modules on the client side.
</p>
<p>Expand may not be the best word for what this request does. It does not
necessarily tell you all the files contained in a module, for example.
Basically it is a way of telling you which working directories the
server needs to know about in order to handle a checkout of the
specified modules.
</p>
<p>For example, suppose that the server has a module defined by
</p>
<div class="example">
<pre class="example-preformatted">aliasmodule -a 1dir
</pre></div>
<p>That is, one can check out <code class="code">aliasmodule</code> and it will take
<code class="code">1dir</code> in the repository and check it out to <code class="code">1dir</code> in the
working directory. Now suppose the client already has this module
checked out and is planning on using the <code class="code">co</code> request to update it.
Without using <code class="code">expand-modules</code>, the client would have two bad
choices: it could either send information about <em class="emph">all</em> working
directories under the current directory, which could be unnecessarily
slow, or it could be ignorant of the fact that <code class="code">aliasmodule</code> stands
for <code class="code">1dir</code>, and neglect to send information for <code class="code">1dir</code>, which
would lead to incorrect operation.
</p>
<p>With <code class="code">expand-modules</code>, the client would first ask for the module to
be expanded:
</p>
<div class="example">
<pre class="example-preformatted">C: Root /home/kingdon/zwork/cvsroot
. . .
C: Argument aliasmodule
C: Directory .
C: .
C: expand-modules
S: Module-expansion 1dir
S: ok
</pre></div>
<p>and then it knows to check the <samp class="file">1dir</samp> directory and send
requests such as <code class="code">Entry</code> and <code class="code">Modified</code> for the files in that
directory.
</p>
</dd>
<dt><code class="code">ci \n</code></dt>
<dt><code class="code">diff \n</code></dt>
<dt><code class="code">list \n</code></dt>
<dt><code class="code">tag \n</code></dt>
<dt><code class="code">status \n</code></dt>
<dt><code class="code">admin \n</code></dt>
<dt><code class="code">history \n</code></dt>
<dt><code class="code">watchers \n</code></dt>
<dt><code class="code">editors \n</code></dt>
<dt><code class="code">annotate \n</code></dt>
<dd><p>Response expected: yes. Actually do a cvs command. This uses any
previous <code class="code">Argument</code>, <code class="code">Directory</code>, <code class="code">Entry</code>, or
<code class="code">Modified</code> requests, if they have been sent. The
last <code class="code">Directory</code> sent specifies the working directory at the time
of the operation. No provision is made for any input from the user.
This means that <code class="code">ci</code> must use a <code class="code">-m</code> argument if it wants to
specify a log message.
</p>
</dd>
<dt><code class="code">log \n</code></dt>
<dd><p>Response expected: yes. Show information for past revisions. This uses
any previous <code class="code">Directory</code>, <code class="code">Entry</code>, or <code class="code">Modified</code>
requests, if they have been sent. The last <code class="code">Directory</code> sent
specifies the working directory at the time of the operation. Also uses
previous <code class="code">Argument</code>’s of which the canonical forms are the
following (<small class="sc">CVS</small> 1.10 and older clients sent what the user specified,
but clients are encouraged to use the canonical forms and other forms
are deprecated):
</p>
<dl class="table">
<dt><code class="code">-b, -h, -l, -N, -R, -t</code></dt>
<dd><p>These options go by themselves, one option per <code class="code">Argument</code> request.
</p>
</dd>
<dt><code class="code">-d <var class="var">date1</var><<var class="var">date2</var></code></dt>
<dd><p>Select revisions between <var class="var">date1</var> and <var class="var">date2</var>. Either date
may be omitted in which case there is no date limit at that end of the
range (clients may specify dates such as 1 Jan 1970 or 1 Jan 2038 for
similar purposes but this is problematic as it makes assumptions about
what dates the server supports). Dates are in RFC822/1123 format. The
‘<samp class="samp">-d</samp>’ is one <code class="code">Argument</code> request and the date range is a second
one.
</p>
</dd>
<dt><code class="code">-d <var class="var">date1</var><=<var class="var">date2</var></code></dt>
<dd><p>Likewise but compare dates for equality.
</p>
</dd>
<dt><code class="code">-d <var class="var">singledate</var></code></dt>
<dd><p>Select the single, latest revision dated <var class="var">singledate</var> or earlier.
</p>
<p>To include several date ranges and/or singledates, repeat the ‘<samp class="samp">-d</samp>’
option as many times as necessary.
</p>
</dd>
<dt><code class="code">-r<var class="var">rev1</var>:<var class="var">rev2</var></code></dt>
<dt><code class="code">-r<var class="var">branch</var></code></dt>
<dt><code class="code">-r<var class="var">branch</var>.</code></dt>
<dt><code class="code">-r</code></dt>
<dd><p>Specify revisions (note that <var class="var">rev1</var> or <var class="var">rev2</var> can be omitted, or
can refer to branches). Send both the ‘<samp class="samp">-r</samp>’ and the revision
information in a single <code class="code">Argument</code> request. To include several
revision selections, repeat the ‘<samp class="samp">-r</samp>’ option.
</p>
</dd>
<dt><code class="code">-s <var class="var">state</var></code></dt>
<dt><code class="code">-w</code></dt>
<dt><code class="code">-w<var class="var">login</var></code></dt>
<dd><p>Select on states or users. To include more than one state or user,
repeat the option. Send the ‘<samp class="samp">-s</samp>’ option as a separate argument
from the state being selected. Send the ‘<samp class="samp">-w</samp>’ option as part of the
same argument as the user being selected.
</p></dd>
</dl>
</dd>
<dt><code class="code">co \n</code></dt>
<dd><p>Response expected: yes. Get files from the repository. This uses any
previous <code class="code">Argument</code>, <code class="code">Directory</code>, <code class="code">Entry</code>, or
<code class="code">Modified</code> requests, if they have been sent. Arguments to this
command are module names; the client cannot know what directories they
correspond to except by (1) just sending the <code class="code">co</code> request, and then
seeing what directory names the server sends back in its responses, and
(2) the <code class="code">expand-modules</code> request.
</p>
</dd>
<dt><code class="code">export \n</code></dt>
<dd><p>Response expected: yes. Get files from the repository. This uses any
previous <code class="code">Argument</code>, <code class="code">Directory</code>, <code class="code">Entry</code>, or
<code class="code">Modified</code> requests, if they have been sent. Arguments to this
command are module names, as described for the <code class="code">co</code> request. The
intention behind this command is that a client can get sources from a
server without storing CVS information about those sources. That is, a
client probably should not count on being able to take the entries line
returned in the <code class="code">Created</code> response from an <code class="code">export</code> request
and send it in a future <code class="code">Entry</code> request. Note that the entries
line in the <code class="code">Created</code> response must indicate whether the file is
binary or text, so the client can create it correctly.
</p>
</dd>
<dt><code class="code">ls \n</code></dt>
<dt><code class="code">rannotate \n</code></dt>
<dt><code class="code">rdiff \n</code></dt>
<dt><code class="code">rlist \n</code></dt>
<dt><code class="code">rlog \n</code></dt>
<dt><code class="code">rtag \n</code></dt>
<dd><p>Response expected: yes. Actually do a cvs command. This uses any
previous <code class="code">Argument</code> requests, if they have been sent. The client
should not send <code class="code">Directory</code>, <code class="code">Entry</code>, or <code class="code">Modified</code>
requests for these commands; they are not used. Arguments to these
commands are module names, as described for <code class="code">co</code>. <code class="code">ls</code> is a
synonym for <code class="code">rlist</code>, for compatibility with CVSNT.
</p>
</dd>
<dt><code class="code">init <var class="var">root-name</var> \n</code></dt>
<dd><p>Response expected: yes. If it doesn’t already exist, create a <small class="sc">CVS</small>
repository <var class="var">root-name</var>. Note that <var class="var">root-name</var> is a local
directory and <em class="emph">not</em> a fully qualified <code class="code">CVSROOT</code> variable.
The <code class="code">Root</code> request need not have been previously sent.
</p>
</dd>
<dt><code class="code">suck \n</code></dt>
<dd><p>Response expected: yes.
Actually do a <code class="code">cvs suck</code> command.
This uses a previous <code class="code">Argument</code> request (only one, because the
<code class="code">cvs suck</code> CLI command takes only one).
This is an extension specific to MirBSD, MirPorts and Debian.
</p>
</dd>
<dt><code class="code">update \n</code></dt>
<dd><p>Response expected: yes. Actually do a <code class="code">cvs update</code> command. This
uses any previous <code class="code">Argument</code>, <code class="code">Directory</code>, <code class="code">Entry</code>,
or <code class="code">Modified</code> requests, if they have been sent. The
last <code class="code">Directory</code> sent specifies the working directory at the time
of the operation. The <code class="code">-I</code> option is not used–files which the
client can decide whether to ignore are not mentioned and the client
sends the <code class="code">Questionable</code> request for others.
</p>
</dd>
<dt><code class="code">import \n</code></dt>
<dd><p>Response expected: yes. Actually do a <code class="code">cvs import</code> command. This
uses any previous <code class="code">Argument</code>, <code class="code">Directory</code>, <code class="code">Entry</code>, or
<code class="code">Modified</code> requests, if they have been sent. The
last <code class="code">Directory</code> sent specifies the working directory at the time
of the operation - unlike most commands, the repository field of each
<code class="code">Directory</code> request is ignored (it merely must point somewhere
within the root). The files to be imported are sent in <code class="code">Modified</code>
requests (files which the client knows should be ignored are not sent;
the server must still process the CVSROOT/cvsignore file unless -I ! is
sent). A log message must have been specified with a <code class="code">-m</code>
argument.
</p>
</dd>
<dt><code class="code">add \n</code></dt>
<dd><p>Response expected: yes. Add a file or directory. This uses any
previous <code class="code">Argument</code>, <code class="code">Directory</code>, <code class="code">Entry</code>, or
<code class="code">Modified</code> requests, if they have been sent. The
last <code class="code">Directory</code> sent specifies the working directory at the time
of the operation.
</p>
<p>To add a directory, send the directory to be added using
<code class="code">Directory</code> and <code class="code">Argument</code> requests. For example:
</p>
<div class="example">
<pre class="example-preformatted">C: Root /u/cvsroot
. . .
C: Argument nsdir
C: Directory nsdir
C: 1dir/nsdir
C: Directory .
C: 1dir
C: add
S: M Directory /u/cvsroot/1dir/nsdir put under version control
S: ok
</pre></div>
<p>You will notice that the server does not signal to the client in any
particular way that the directory has been successfully added. The
client is supposed to just assume that the directory has been added and
update its records accordingly. Note also that adding a directory is
immediate; it does not wait until a <code class="code">ci</code> request as files do.
</p>
<p>To add a file, send the file to be added using a <code class="code">Modified</code>
request. For example:
</p>
<div class="example">
<pre class="example-preformatted">C: Argument nfile
C: Directory .
C: 1dir
C: Modified nfile
C: u=rw,g=r,o=r
C: 6
C: hello
C: add
S: E cvs server: scheduling file `nfile' for addition
S: Mode u=rw,g=r,o=r
S: Checked-in ./
S: /u/cvsroot/1dir/nfile
S: /nfile/0///
S: E cvs server: use 'cvs commit' to add this file permanently
S: ok
</pre></div>
<p>Note that the file has not been added to the repository; the only effect
of a successful <code class="code">add</code> request, for a file, is to supply the client
with a new entries line containing ‘<samp class="samp">0</samp>’ to indicate an added file.
In fact, the client probably could perform this operation without
contacting the server, although using <code class="code">add</code> does cause the server
to perform a few more checks.
</p>
<p>The client sends a subsequent <code class="code">ci</code> to actually add the file to the
repository.
</p>
<p>Another quirk of the <code class="code">add</code> request is that with CVS 1.9 and older,
a pathname specified in
an <code class="code">Argument</code> request cannot contain ‘<samp class="samp">/</samp>’. There is no good
reason for this restriction, and in fact more recent CVS servers don’t
have it.
But the way to interoperate with the older servers is to ensure that
all <code class="code">Directory</code> requests for <code class="code">add</code> (except those used to add
directories, as described above), use ‘<samp class="samp">.</samp>’ for
<var class="var">local-directory</var>. Specifying another string for
<var class="var">local-directory</var> may not get an error, but it will get you strange
<code class="code">Checked-in</code> responses from the buggy servers.
</p>
</dd>
<dt><code class="code">remove \n</code></dt>
<dd><p>Response expected: yes. Remove a file. This uses any
previous <code class="code">Argument</code>, <code class="code">Directory</code>, <code class="code">Entry</code>, or
<code class="code">Modified</code> requests, if they have been sent. The
last <code class="code">Directory</code> sent specifies the working directory at the time
of the operation.
</p>
<p>Note that this request does not actually do anything to the repository;
the only effect of a successful <code class="code">remove</code> request is to supply the
client with a new entries line containing ‘<samp class="samp">-</samp>’ to indicate a removed
file. In fact, the client probably could perform this operation without
contacting the server, although using <code class="code">remove</code> may cause the server
to perform a few more checks.
</p>
<p>The client sends a subsequent <code class="code">ci</code> request to actually record the
removal in the repository.
</p>
</dd>
<dt><code class="code">edit \n</code></dt>
<dd><p>Response expected: yes. Actually do the <code class="code">cvs edit</code> command. This uses
any previous <code class="code">Argument</code>, <code class="code">Directory</code>, <code class="code">Entry</code>, <code class="code">LocalDir</code>,
or <code class="code">Hostname</code> requests, if they have been sent. Unless the user has
requested that edits not be granted unless no one else is editing a file, a
local edit followed by an attempt to send <code class="code">Notify</code> requests to the
server is preferred.
</p>
</dd>
<dt><code class="code">watch-on \n</code></dt>
<dt><code class="code">watch-off \n</code></dt>
<dt><code class="code">watch-add \n</code></dt>
<dt><code class="code">watch-remove \n</code></dt>
<dd><p>Response expected: yes. Actually do the <code class="code">cvs watch on</code>, <code class="code">cvs
watch off</code>, <code class="code">cvs watch add</code>, and <code class="code">cvs watch remove</code> commands,
respectively. This uses any previous <code class="code">Argument</code>,
<code class="code">Directory</code>, <code class="code">Entry</code>, or <code class="code">Modified</code>
requests, if they have been sent. The last <code class="code">Directory</code> sent
specifies the working directory at the time of the operation.
</p>
</dd>
<dt><code class="code">release \n</code></dt>
<dd><p>Response expected: yes. Note that a <code class="code">cvs release</code> command has
taken place and update the history file accordingly.
</p>
</dd>
<dt><code class="code">global-list-quiet \n</code></dt>
<dd><p>Response expected: yes. This request is a synonym for noop, but its existance
notifies the client that a <code class="code">-q</code> option to <code class="code">list</code> and <code class="code">rlist</code>
will be rejected. This, in a reverse-logic sort of way, is here so that when
it <em class="emph">isn’t</em> received, as for instance from CVSNT, the client will know that
the quiet option has to be sent as a command option rather than a global
option.
</p>
</dd>
<dt><code class="code">noop \n</code></dt>
<dd><p>Response expected: yes. This request is a null command in the sense
that it doesn’t do anything, but merely (as with any other requests
expecting a response) sends back any responses pertaining to pending
errors, pending <code class="code">Notified</code> responses, etc.
The <code class="code">Root</code> request need not have been previously sent.
</p>
</dd>
<dt><code class="code">update-patches \n</code></dt>
<dd><p>Response expected: yes.
This request does not actually do anything. It is used as a signal that
the server is able to generate patches when given an <code class="code">update</code>
request. The client must issue the <code class="code">-u</code> argument to <code class="code">update</code>
in order to receive patches.
</p>
</dd>
<dt><code class="code">gzip-file-contents <var class="var">level</var> \n</code></dt>
<dd><p>Response expected: no. Note that this request does not follow the
response convention stated above. <code class="code">Gzip-stream</code> is suggested
instead of <code class="code">gzip-file-contents</code> as it gives better compression; the
only reason to implement the latter is to provide compression with
<small class="sc">CVS</small> 1.8 and earlier. The <code class="code">gzip-file-contents</code> request asks
the server to compress files it sends to the client using <code class="code">gzip</code>
(RFC1952/1951) compression, using the specified level of compression.
If this request is not made, the server must not compress files.
</p>
<p>This is only a hint to the server. It may still decide (for example, in
the case of very small files, or files that already appear to be
compressed) not to do the compression. Compression is indicated by a
‘<samp class="samp">z</samp>’ preceding the file length.
</p>
<p>Availability of this request in the server indicates to the client that
it may compress files sent to the server, regardless of whether the
client actually uses this request.
</p>
</dd>
<dt><code class="code">wrapper-sendme-rcsOptions \n</code></dt>
<dd><p>Response expected: yes.
Request that the server transmit mappings from filenames to keyword
expansion modes in <code class="code">Wrapper-rcsOption</code> responses.
</p>
</dd>
<dt><code class="code">version \n</code></dt>
<dd><p>Response expected: yes.
Request that the server transmit its version message.
The <code class="code">Root</code> request need not have been previously sent.
</p>
</dd>
<dt><code class="code"><var class="var">other-request</var> <var class="var">text</var> \n</code></dt>
<dd><p>Response expected: yes.
Any unrecognised request expects a response, and does not
contain any additional data. The response will normally be something like
‘<samp class="samp">error unrecognized request</samp>’, but it could be a different error if
a previous request which doesn’t expect a response produced an error.
</p></dd>
</dl>
<p>When the client is done, it drops the connection.
</p>
<hr>
</div>
<div class="section-level-extent" id="Response-intro">
<div class="nav-panel">
<p>
Next: <a href="#Response-pathnames" accesskey="n" rel="next">The "pathname" in responses</a>, Previous: <a href="#Requests" accesskey="p" rel="prev">Requests</a>, Up: <a href="#Protocol" accesskey="u" rel="up">The CVS client/server protocol</a> </p>
</div>
<h3 class="section" id="Introduction-to-Responses"><span>5.9 Introduction to Responses<a class="copiable-link" href="#Introduction-to-Responses"> ¶</a></span></h3>
<p>After a command which expects a response, the server sends however many
of the following responses are appropriate. The server should not send
data at other times (the current implementation may violate this
principle in a few minor places, where the server is printing an error
message and exiting—this should be investigated further).
</p>
<p>Any set of responses always ends with ‘<samp class="samp">error</samp>’ or ‘<samp class="samp">ok</samp>’. This
indicates that the response is over.
</p>
<p>The responses <code class="code">Checked-in</code>, <code class="code">New-entry</code>, <code class="code">Updated</code>,
<code class="code">Created</code>, <code class="code">Update-existing</code>, <code class="code">Merged</code>, and
<code class="code">Patched</code> are refered to as <em class="dfn">file updating</em> responses, because
they change the status of a file in the working directory in some way.
The responses <code class="code">Mode</code>, <code class="code">Mod-time</code>, and <code class="code">Checksum</code> are
referred to as <em class="dfn">file update modifying</em> responses because they modify
the next file updating response. In no case shall a file update
modifying response apply to a file updating response other than the next
one. Nor can the same file update modifying response occur twice for
a given file updating response (if servers diagnose this problem, it may
aid in detecting the case where clients send an update modifying
response without following it by a file updating response).
</p>
<hr>
</div>
<div class="section-level-extent" id="Response-pathnames">
<div class="nav-panel">
<p>
Next: <a href="#Responses" accesskey="n" rel="next">Responses</a>, Previous: <a href="#Response-intro" accesskey="p" rel="prev">Introduction to Responses</a>, Up: <a href="#Protocol" accesskey="u" rel="up">The CVS client/server protocol</a> </p>
</div>
<h3 class="section" id="The-_0022pathname_0022-in-responses"><span>5.10 The "pathname" in responses<a class="copiable-link" href="#The-_0022pathname_0022-in-responses"> ¶</a></span></h3>
<p>Many of the responses contain something called <var class="var">pathname</var>.
The name is somewhat misleading; it actually indicates a pair of
pathnames. First, a local directory name
relative to the directory in which the command was given (i.e. the last
<code class="code">Directory</code> before the command). Then a linefeed and a repository
name. Then a slash and the filename (without a ‘<samp class="samp">,v</samp>’ ending).
</p>
<p>The repository name may be absolute or relative to the <var class="var">pathname</var>
sent with the <code class="code">Root</code> request. If absolute, the repository name must begin
with the <var class="var">pathname</var> sent with the <code class="code">Root</code> request. Relative or
absolute, the repository name must specify a path underneath the <code class="code">Root</code>
<var class="var">pathname</var>.
</p>
<p>For example, for a file <samp class="file">i386.mh</samp>
which is in the local directory <samp class="file">gas.clean/config</samp> and for which
the repository name is <samp class="file">devo/gas/config</samp>:
</p>
<div class="example">
<pre class="example-preformatted">gas.clean/config/
devo/gas/config/i386.mh
</pre></div>
<p>If the server wants to tell the client to create a directory, then it
merely uses the directory in any response, as described above, and the
client should create the directory if it does not exist. Note that this
should only be done one directory at a time, in order to permit the
client to correctly store the repository for each directory. Servers
can use requests such as <code class="code">Clear-sticky</code>,
<code class="code">Clear-static-directory</code>, or any other requests, to create
directories.
</p>
<p>Some server
implementations may poorly distinguish between a directory which should
not exist and a directory which contains no files; in order to refrain
from creating empty directories a client should both send the ‘<samp class="samp">-P</samp>’
option to <code class="code">update</code> or <code class="code">co</code>, and should also detect the case in
which the server asks to create a directory but not any files within it
(in that case the client should remove the directory or refrain from
creating it in the first place). Note that servers could clean this up
greatly by only telling the client to create directories if the
directory in question should exist, but until servers do this, clients
will need to offer the ‘<samp class="samp">-P</samp>’ behavior described above.
</p>
<hr>
</div>
<div class="section-level-extent" id="Responses">
<div class="nav-panel">
<p>
Next: <a href="#Text-tags" accesskey="n" rel="next">Tags for the MT tagged text response</a>, Previous: <a href="#Response-pathnames" accesskey="p" rel="prev">The "pathname" in responses</a>, Up: <a href="#Protocol" accesskey="u" rel="up">The CVS client/server protocol</a> </p>
</div>
<h3 class="section" id="Responses-1"><span>5.11 Responses<a class="copiable-link" href="#Responses-1"> ¶</a></span></h3>
<p>Here are the responses:
</p>
<dl class="table">
<dt><code class="code">Valid-requests <var class="var">request-list</var> \n</code></dt>
<dd><p>Indicate what requests the server will accept. <var class="var">request-list</var>
is a space separated list of tokens. If the server supports sending
patches, it will include ‘<samp class="samp">update-patches</samp>’ in this list. The
‘<samp class="samp">update-patches</samp>’ request does not actually do anything.
</p>
</dd>
<dt><code class="code">Force-gzip \n</code></dt>
<dd><p>Response expected: no.
Indicates that the server requires compression. The client must send a
<code class="code">Gzip-stream</code> request, though the requested <var class="var">level</var> may be ‘<samp class="samp">0</samp>’.
</p>
</dd>
<dt><code class="code">Referrer <var class="var">CVSROOT</var></code></dt>
<dd><p>Request that the client store <var class="var">CVSROOT</var> as the name of this server and that
this name be passed via a <code class="code">Referrer</code> <em class="emph">request</em> to any subsequent
servers contacted as a result of a <code class="code">Redirect</code> response. This can be
useful to allow the secondary administrator to configure the <code class="code">CVSROOT</code> the
primary should use to update the secondary in case the client uses a
non-standard name or even a name that is unique to the client for some reason.
</p>
</dd>
<dt><code class="code">Redirect <var class="var">CVSROOT</var></code></dt>
<dd><p>Request that the client redirect its connection to <var class="var">CVSROOT</var> and begin
again. This response is only valid in response to a <code class="code">Command-prep</code>
request. If a client receives this response, it is expected to notify the
write server it subsequently contacts of the CVSROOT of the server which
redirected it using the ‘<samp class="samp">Referrer</samp>’ request. This information makes it
possible for primary servers to update the client’s mirror first, hopefully
minimizing race conditions on subsequent updates from the same client.
</p>
</dd>
<dt><code class="code">Checked-in <var class="var">pathname</var> \n</code></dt>
<dd><p>Additional data: New Entries line, \n. This means a file <var class="var">pathname</var>
has been successfully operated on (checked in, added, etc.). name in
the Entries line is the same as the last component of <var class="var">pathname</var>.
</p>
</dd>
<dt><code class="code">New-entry <var class="var">pathname</var> \n</code></dt>
<dd><p>Additional data: New Entries line, \n. Like <code class="code">Checked-in</code>, but the
file is not up to date.
</p>
</dd>
<dt><code class="code">Updated <var class="var">pathname</var> \n</code></dt>
<dd><p>Additional data: New Entries line, \n, mode, \n, file transmission. A
new copy of the file is enclosed. This is used for a new revision of an
existing file, or for a new file, or for any other case in which the
local (client-side) copy of the file needs to be updated, and after
being updated it will be up to date. If any directory in pathname does
not exist, create it. This response is not used if <code class="code">Created</code> and
<code class="code">Update-existing</code> are supported.
</p>
</dd>
<dt><code class="code">Created <var class="var">pathname</var> \n</code></dt>
<dd><p>This is just like <code class="code">Updated</code> and takes the same additional data, but
is used only if no <code class="code">Entry</code>, <code class="code">Modified</code>, or
<code class="code">Unchanged</code> request has been sent for the file in question. The
distinction between <code class="code">Created</code> and <code class="code">Update-existing</code> is so
that the client can give an error message in several cases: (1) there is
a file in the working directory, but not one for which <code class="code">Entry</code>,
<code class="code">Modified</code>, or <code class="code">Unchanged</code> was sent (for example, a file which
was ignored, or a file for which <code class="code">Questionable</code> was sent), (2)
there is a file in the working directory whose name differs from the one
mentioned in <code class="code">Created</code> in ways that the client is unable to use to
distinguish files. For example, the client is case-insensitive and the
names differ only in case.
</p>
</dd>
<dt><code class="code">Update-existing <var class="var">pathname</var> \n</code></dt>
<dd><p>This is just like <code class="code">Updated</code> and takes the same additional data, but
is used only if a <code class="code">Entry</code>, <code class="code">Modified</code>, or <code class="code">Unchanged</code>
request has been sent for the file in question.
</p>
<p>This response, or <code class="code">Merged</code>, indicates that the server has
determined that it is OK to overwrite the previous contents of the file
specified by <var class="var">pathname</var>. Provided that the client has correctly
sent <code class="code">Modified</code> or <code class="code">Is-modified</code> requests for a modified file,
and the file was not modified while CVS was running, the server can
ensure that a user’s modifications are not lost.
</p>
</dd>
<dt><code class="code">Merged <var class="var">pathname</var> \n</code></dt>
<dd><p>This is just like <code class="code">Updated</code> and takes the same additional data,
with the one difference that after the new copy of the file is enclosed,
it will still not be up to date. Used for the results of a merge, with
or without conflicts.
</p>
<p>It is useful to preserve an copy of what the file looked like before the
merge. This is basically handled by the server; before sending
<code class="code">Merged</code> it will send a <code class="code">Copy-file</code> response. For example, if
the file is <samp class="file">aa</samp> and it derives from revision 1.3, the
<code class="code">Copy-file</code> response will tell the client to copy <samp class="file">aa</samp> to
<samp class="file">.#aa.1.3</samp>. It is up to the client to decide how long to keep this
file around; traditionally clients have left it around forever, thus
letting the user clean it up as desired. But another answer, such as
until the next commit, might be preferable.
</p>
</dd>
<dt><code class="code">Rcs-diff <var class="var">pathname</var> \n</code></dt>
<dd><p>This is just like <code class="code">Updated</code> and takes the same additional data,
with the one difference that instead of sending a new copy of the file,
the server sends an RCS change text. This change text is produced by
‘<samp class="samp">diff -n</samp>’ (the GNU diff ‘<samp class="samp">-a</samp>’ option may also be used). The
client must apply this change text to the existing file. This will only
be used when the client has an exact copy of an earlier revision of a
file. This response is only used if the <code class="code">update</code> command is given
the ‘<samp class="samp">-u</samp>’ argument.
</p>
</dd>
<dt><code class="code">Patched <var class="var">pathname</var> \n</code></dt>
<dd><p>This is just like <code class="code">Rcs-diff</code> and takes the same additional data,
except that it sends a standard patch rather than an RCS change text.
The patch is produced by ‘<samp class="samp">diff -c</samp>’ for <small class="sc">CVS</small> 1.6 and later (see
POSIX.2 for a description of this format), or ‘<samp class="samp">diff -u</samp>’ for
previous versions of <small class="sc">CVS</small>; clients are encouraged to accept either
format. Like <code class="code">Rcs-diff</code>, this response is only used if the
<code class="code">update</code> command is given the ‘<samp class="samp">-u</samp>’ argument.
</p>
<p>The <code class="code">Patched</code> response is deprecated in favor of the
<code class="code">Rcs-diff</code> response. However, older clients (CVS 1.9 and earlier)
only support <code class="code">Patched</code>.
</p>
</dd>
<dt><code class="code">Edit-file <var class="var">pathname</var> \n</code></dt>
<dd><p>Do the client-side portion of editing a file.
</p>
</dd>
<dt><code class="code">Mode <var class="var">mode</var> \n</code></dt>
<dd><p>This <var class="var">mode</var> applies to the next file mentioned in
<code class="code">Checked-in</code>. <code class="code">Mode</code> is a file update modifying response
as described in <a class="ref" href="#Response-intro">Introduction to Responses</a>.
</p>
</dd>
<dt><code class="code">Mod-time <var class="var">time</var> \n</code></dt>
<dd><p>Set the modification time of the next file sent to <var class="var">time</var>.
<code class="code">Mod-time</code> is a file update modifying response
as described in <a class="ref" href="#Response-intro">Introduction to Responses</a>.
The
<var class="var">time</var> is in the format specified by RFC822 as modified by RFC1123.
The server may specify any timezone it chooses; clients will want to
convert that to their own timezone as appropriate. An example of this
format is:
</p>
<div class="example">
<pre class="example-preformatted">26 May 1997 13:01:40 -0400
</pre></div>
<p>There is no requirement that the client and server clocks be
synchronised. The server just sends its recommendation for a timestamp
(based on its own clock, presumably), and the client should just believe
it (this means that the time might be in the future, for example).
</p>
<p>If the server does not send <code class="code">Mod-time</code> for a given file, the client
should pick a modification time in the usual way (usually, just let the
operating system set the modification time to the time that the CVS
command is running).
</p>
</dd>
<dt><code class="code">Checksum <var class="var">checksum</var>\n</code></dt>
<dd><p>The <var class="var">checksum</var> applies to the next file sent (that is,
<code class="code">Checksum</code> is a file update modifying response
as described in <a class="ref" href="#Response-intro">Introduction to Responses</a>).
In the case of
<code class="code">Patched</code>, the checksum applies to the file after being patched,
not to the patch itself. The client should compute the checksum itself,
after receiving the file or patch, and signal an error if the checksums
do not match. The checksum is the 128 bit MD5 checksum represented as
32 hex digits (MD5 is described in RFC1321).
This response is optional, and is only used if the
client supports it (as judged by the <code class="code">Valid-responses</code> request).
</p>
</dd>
<dt><code class="code">Copy-file <var class="var">pathname</var> \n</code></dt>
<dd><p>Additional data: <var class="var">newname</var> \n. Copy file <var class="var">pathname</var> to
<var class="var">newname</var> in the same directory where it already is. This does not
affect <code class="code">CVS/Entries</code>.
</p>
<p>This can optionally be implemented as a rename instead of a copy. The
only use for it which currently has been identified is prior to a
<code class="code">Merged</code> response as described under <code class="code">Merged</code>. Clients can
probably assume that is how it is being used, if they want to worry
about things like how long to keep the <var class="var">newname</var> file around.
</p>
</dd>
<dt><code class="code">Removed <var class="var">pathname</var> \n</code></dt>
<dd><p>The file has been removed from the repository (this is the case where
cvs prints ‘<samp class="samp">file foobar.c is no longer pertinent</samp>’).
</p>
</dd>
<dt><code class="code">Remove-entry <var class="var">pathname</var> \n</code></dt>
<dd><p>The file needs its entry removed from <code class="code">CVS/Entries</code>, but the file
itself is already gone (this happens in response to a <code class="code">ci</code> request
which involves committing the removal of a file).
</p>
</dd>
<dt><code class="code">Set-static-directory <var class="var">pathname</var> \n</code></dt>
<dd><p>This instructs the client to set the <code class="code">Entries.Static</code> flag, which
it should then send back to the server in a <code class="code">Static-directory</code>
request whenever the directory is operated on. <var class="var">pathname</var> ends in a
slash; its purpose is to specify a directory, not a file within a
directory.
</p>
</dd>
<dt><code class="code">Clear-static-directory <var class="var">pathname</var> \n</code></dt>
<dd><p>Like <code class="code">Set-static-directory</code>, but clear, not set, the flag.
</p>
</dd>
<dt><code class="code">Set-sticky <var class="var">pathname</var> \n</code></dt>
<dd><p>Additional data: <var class="var">tagspec</var> \n. Tell the client to set a sticky tag
or date, which should be supplied with the <code class="code">Sticky</code> request for
future operations. <var class="var">pathname</var> ends in a slash; its purpose is to
specify a directory, not a file within a directory. The client should
store <var class="var">tagspec</var> and pass it back to the server as-is, to allow for
future expansion. The first character of <var class="var">tagspec</var> is ‘<samp class="samp">T</samp>’ for
a tag, ‘<samp class="samp">D</samp>’ for a date, or something else for future expansion. The
remainder of <var class="var">tagspec</var> contains the actual tag or date.
</p>
</dd>
<dt><code class="code">Clear-sticky <var class="var">pathname</var> \n</code></dt>
<dd><p>Clear any sticky tag or date set by <code class="code">Set-sticky</code>.
</p>
</dd>
<dt><code class="code">Template <var class="var">pathname</var> \n</code></dt>
<dd><p>Additional data: file transmission (note: compressed file transmissions
are not supported). <var class="var">pathname</var> ends in a slash; its purpose is to
specify a directory, not a file within a directory. Tell the client to
store the file transmission as the template log message, and then use
that template in the future when prompting the user for a log message.
</p>
</dd>
<dt><code class="code">Set-checkin-prog <var class="var">dir</var> \n</code></dt>
<dd><p>Additional data: <var class="var">prog</var> \n. Tell the client to set a checkin
program, which should be supplied with the <code class="code">Checkin-prog</code> request
for future operations.
</p>
</dd>
<dt><code class="code">Set-update-prog <var class="var">dir</var> \n</code></dt>
<dd><p>Additional data: <var class="var">prog</var> \n. Tell the client to set an update
program, which should be supplied with the <code class="code">Update-prog</code> request
for future operations.
</p>
</dd>
<dt><code class="code">Notified <var class="var">pathname</var> \n</code></dt>
<dd><p>Indicate to the client that the notification for <var class="var">pathname</var> has been
done. There should be one such response for every <code class="code">Notify</code>
request; if there are several <code class="code">Notify</code> requests for a single file,
the requests should be processed in order; the first <code class="code">Notified</code>
response pertains to the first <code class="code">Notify</code> request, etc.
</p>
</dd>
<dt><code class="code">Module-expansion <var class="var">pathname</var> \n</code></dt>
<dd><p>Return a file or directory
which is included in a particular module. <var class="var">pathname</var> is relative
to cvsroot, unlike most pathnames in responses. <var class="var">pathname</var> should
be used to look and see whether some or all of the module exists on
the client side; it is not necessarily suitable for passing as an
argument to a <code class="code">co</code> request (for example, if the modules file
contains the ‘<samp class="samp">-d</samp>’ option, it will be the directory specified with
‘<samp class="samp">-d</samp>’, not the name of the module).
</p>
</dd>
<dt><code class="code">Wrapper-rcsOption <var class="var">pattern</var> -k '<var class="var">option</var>' \n</code></dt>
<dd><p>Transmit to the client a filename pattern which implies a certain
keyword expansion mode. The <var class="var">pattern</var> is a wildcard pattern (for
example, ‘<samp class="samp">*.exe</samp>’. The <var class="var">option</var> is ‘<samp class="samp">b</samp>’ for binary, and so
on. Note that although the syntax happens to resemble the syntax in
certain CVS configuration files, it is more constrained; there must be
exactly one space between <var class="var">pattern</var> and ‘<samp class="samp">-k</samp>’ and exactly one
space between ‘<samp class="samp">-k</samp>’ and ‘<samp class="samp">'</samp>’, and no string is permitted in
place of ‘<samp class="samp">-k</samp>’ (extensions should be done with new responses, not by
extending this one, for graceful handling of <code class="code">Valid-responses</code>).
</p>
</dd>
<dt><code class="code">M <var class="var">text</var> \n</code></dt>
<dd><p>A one-line message for the user.
Note that the format of <var class="var">text</var> is not designed for machine parsing.
Although sometimes scripts and clients will have little choice, the
exact text which is output is subject to vary at the discretion of the
server and the example output given in this document is just that,
example output. Servers are encouraged to use the ‘<samp class="samp">MT</samp>’ response,
and future versions of this document will hopefully standardise more of
the ‘<samp class="samp">MT</samp>’ tags; see <a class="ref" href="#Text-tags">Tags for the MT tagged text response</a>.
</p>
</dd>
<dt><code class="code">LOGM <var class="var">text</var> \n</code></dt>
<dd><p>Exactly the same as <code class="code">M</code> but only sent if the client indicates
supporting it via <code class="code">Valid-responses</code>, used exclusively for log
message payload (that is, in <code class="code">cvs log</code> and <code class="code">cvs rlog</code>,
the text body the user originally has entered with the ‘<samp class="samp">-m</samp>’
option to the <code class="code">ci</code> request).
</p>
</dd>
<dt><code class="code">Mbinary \n</code></dt>
<dd><p>Additional data: file transmission (note: compressed file transmissions
are not supported). This is like <code class="code">M</code>, except the contents of the
file transmission are binary and should be copied to standard output
without translation to local text file conventions. To transmit a text
file to standard output, servers should use a series of <code class="code">M</code> requests.
</p>
</dd>
<dt><code class="code">E <var class="var">text</var> \n</code></dt>
<dd><p>Same as <code class="code">M</code> but send to stderr not stdout.
</p>
</dd>
<dt><code class="code">F \n</code></dt>
<dd><p>Flush stderr. That is, make it possible for the user to see what has
been written to stderr (it is up to the implementation to decide exactly
how far it should go to ensure this).
</p>
</dd>
<dt><code class="code">MT <var class="var">tagname</var> <var class="var">data</var> \n</code></dt>
<dd>
<p>This response provides for tagged text. It is similar to
SGML/HTML/XML in that the data is structured and a naive application
can also make some sense of it without understanding the structure.
The syntax is not SGML-like, however, in order to fit into the CVS
protocol better and (more importantly) to make it easier to parse,
especially in a language like perl or awk.
</p>
<p>The <var class="var">tagname</var> can have several forms. If it starts with ‘<samp class="samp">a</samp>’
to ‘<samp class="samp">z</samp>’ or ‘<samp class="samp">A</samp>’ to ‘<samp class="samp">Z</samp>’, then it represents tagged text.
If the implementation recognises <var class="var">tagname</var>, then it may interpret
<var class="var">data</var> in some particular fashion. If the implementation does not
recognise <var class="var">tagname</var>, then it should simply treat <var class="var">data</var> as
text to be sent to the user (similar to an <code class="code">M</code> response). There
are two tags which are general purpose. The ‘<samp class="samp">text</samp>’ tag is
similar to an unrecognised tag in that it provides text which will
ordinarily be sent to the user. The ‘<samp class="samp">newline</samp>’ tag is used
without <var class="var">data</var> and indicates that a newline will ordinarily be
sent to the user (there is no provision for embedding newlines in the
<var class="var">data</var> of other tagged text responses).
</p>
<p>If <var class="var">tagname</var> starts with ‘<samp class="samp">+</samp>’ it indicates a start tag and if
it starts with ‘<samp class="samp">-</samp>’ it indicates an end tag. The remainder of
<var class="var">tagname</var> should be the same for matching start and end tags, and
tags should be nested (for example one could have tags in the
following order <code class="code">+bold</code> <code class="code">+italic</code> <code class="code">text</code> <code class="code">-italic</code>
<code class="code">-bold</code> but not <code class="code">+bold</code> <code class="code">+italic</code> <code class="code">text</code>
<code class="code">-bold</code> <code class="code">-italic</code>). A particular start and end tag may be
documented to constrain the tagged text responses which are valid
between them.
</p>
<p>Note that if <var class="var">data</var> is present there will always be exactly one
space between <var class="var">tagname</var> and <var class="var">data</var>; if there is more than one
space, then the spaces beyond the first are part of <var class="var">data</var>.
</p>
<p>Here is an example of some tagged text responses. Note that there is
a trailing space after ‘<samp class="samp">Checking in</samp>’ and ‘<samp class="samp">initial revision:</samp>’
and there are two trailing spaces after ‘<samp class="samp"><--</samp>’. Such trailing
spaces are, of course, part of <var class="var">data</var>.
</p>
<div class="example">
<pre class="example-preformatted">MT +checking-in
MT text Checking in
MT fname gz.tst
MT text ;
MT newline
MT rcsfile /home/kingdon/zwork/cvsroot/foo/gz.tst,v
MT text <--
MT fname gz.tst
MT newline
MT text initial revision:
MT init-rev 1.1
MT newline
MT text done
MT newline
MT -checking-in
</pre></div>
<p>If the client does not support the ‘<samp class="samp">MT</samp>’ response, the same
responses might be sent as:
</p>
<div class="example">
<pre class="example-preformatted">M Checking in gz.tst;
M /home/kingdon/zwork/cvsroot/foo/gz.tst,v <-- gz.tst
M initial revision: 1.1
M done
</pre></div>
<p>For a list of specific tags, see <a class="ref" href="#Text-tags">Tags for the MT tagged text response</a>.
</p>
</dd>
<dt><code class="code">error <var class="var">errno-code</var> ‘<samp class="samp"> </samp>’ <var class="var">text</var> \n</code></dt>
<dd><p>The command completed with an error. <var class="var">errno-code</var> is a symbolic
error code (e.g. <code class="code">ENOENT</code>); if the server doesn’t support this
feature, or if it’s not appropriate for this particular message, it just
omits the errno-code (in that case there are two spaces after
‘<samp class="samp">error</samp>’). Text is an error message such as that provided by
strerror(), or any other message the server wants to use.
The <var class="var">text</var> is like the <code class="code">M</code> response, in the sense that it is
not particularly intended to be machine-parsed; servers may wish to
print an error message with <code class="code">MT</code> responses, and then issue a
<code class="code">error</code> response without <var class="var">text</var> (although it should be noted
that <code class="code">MT</code> currently has no way of flagging the output as intended
for standard error, the way that the <code class="code">E</code> response does).
</p>
</dd>
<dt><code class="code">ok \n</code></dt>
<dd><p>The command completed successfully.
</p></dd>
</dl>
<hr>
</div>
<div class="section-level-extent" id="Text-tags">
<div class="nav-panel">
<p>
Next: <a href="#Example" accesskey="n" rel="next">Example</a>, Previous: <a href="#Responses" accesskey="p" rel="prev">Responses</a>, Up: <a href="#Protocol" accesskey="u" rel="up">The CVS client/server protocol</a> </p>
</div>
<h3 class="section" id="Tags-for-the-MT-tagged-text-response"><span>5.12 Tags for the MT tagged text response<a class="copiable-link" href="#Tags-for-the-MT-tagged-text-response"> ¶</a></span></h3>
<p>The <code class="code">MT</code> response, as described in <a class="ref" href="#Responses">Responses</a>, offers a
way for the server to send tagged text to the client. This section
describes specific tags. The intention is to update this section as
servers add new tags.
</p>
<p>In the following descriptions, <code class="code">text</code> and <code class="code">newline</code> tags are
omitted. Such tags contain information which is intended for users (or
to be discarded), and are subject to change at the whim of the server.
To avoid being vulnerable to such whim, clients should look for the tags
listed here, not <code class="code">text</code>, <code class="code">newline</code>, or other tags.
</p>
<p>The following tag means to indicate to the user that a file has been
updated. It is more or less redundant with the <code class="code">Created</code> and
<code class="code">Update-existing</code> responses, but we don’t try to specify here
whether it occurs in exactly the same circumstances as <code class="code">Created</code>
and <code class="code">Update-existing</code>. The <var class="var">name</var> is the pathname of the file
being updated relative to the directory in which the command is
occurring (that is, the last <code class="code">Directory</code> request which is sent
before the command).
</p>
<div class="example">
<pre class="example-preformatted">MT +updated
MT fname <var class="var">name</var>
MT -updated
</pre></div>
<p>The <code class="code">importmergecmd</code> tag is used when doing an import which has
conflicts, or when doing an import with the ‘<samp class="samp">-X</samp>’ flag.
The client can use it to report how to merge in the newly
imported changes. The <var class="var">count</var> is the number of conflicts, or the
string <code class="code">No</code> if no conflicts occurred. (The latter will only be
sent for imports run with the ‘<samp class="samp">-X</samp>’ flag.) The
newly imported changes can be merged by running the following command:
</p><div class="example smallexample">
<pre class="example-preformatted">cvs checkout -j <var class="var">tag1</var> -j <var class="var">tag2</var> <var class="var">repository</var>
</pre></div>
<div class="example">
<pre class="example-preformatted">MT +importmergecmd
MT conflicts <var class="var">count</var>
MT mergetag1 <var class="var">tag1</var>
MT mergetag2 <var class="var">tag2</var>
MT repository <var class="var">repository</var>
MT -importmergecmd
</pre></div>
<hr>
</div>
<div class="section-level-extent" id="Example">
<div class="nav-panel">
<p>
Next: <a href="#Requirements" accesskey="n" rel="next">Required versus optional parts of the protocol</a>, Previous: <a href="#Text-tags" accesskey="p" rel="prev">Tags for the MT tagged text response</a>, Up: <a href="#Protocol" accesskey="u" rel="up">The CVS client/server protocol</a> </p>
</div>
<h3 class="section" id="Example-1"><span>5.13 Example<a class="copiable-link" href="#Example-1"> ¶</a></span></h3>
<p>Here is an example; lines are prefixed by ‘<samp class="samp">C: </samp>’ to indicate the
client sends them or ‘<samp class="samp">S: </samp>’ to indicate the server sends them.
</p>
<p>The client starts by connecting, sending the root, and completing the
protocol negotiation. In actual practice the lists of valid responses
and requests would be longer.
</p>
<div class="example">
<pre class="example-preformatted">C: Root /u/cvsroot
C: Valid-responses ok error Checked-in M E
C: valid-requests
S: Valid-requests Root Directory Entry Modified Argument Argumentx ci co
S: ok
C: UseUnchanged
</pre></div>
<p>The client wants to check out the <code class="code">supermunger</code> module into a fresh
working directory. Therefore it first expands the <code class="code">supermunger</code>
module; this step would be omitted if the client was operating on a
directory rather than a module.
</p>
<div class="example">
<pre class="example-preformatted">C: Argument supermunger
C: Directory .
C: .
C: expand-modules
</pre></div>
<p>The server replies that the <code class="code">supermunger</code> module expands to the
directory <code class="code">supermunger</code> (the simplest case):
</p>
<div class="example">
<pre class="example-preformatted">S: Module-expansion supermunger
S: ok
</pre></div>
<p>The client then proceeds to check out the directory. The fact that it
sends only a single <code class="code">Directory</code> request which specifies ‘<samp class="samp">.</samp>’
for the working directory means that there is not already a
<code class="code">supermunger</code> directory on the client.
</p>
<div class="example">
<pre class="example-preformatted">C: Argument -N
C: Argument supermunger
C: Directory .
C: .
C: co
</pre></div>
<p>The server replies with the requested files. In this example, there is
only one file, <samp class="file">mungeall.c</samp>. The <code class="code">Clear-sticky</code> and
<code class="code">Clear-static-directory</code> requests are sent by the current
implementation but they have no effect because the default is for those
settings to be clear when a directory is newly created.
</p>
<div class="example">
<pre class="example-preformatted">S: Clear-sticky supermunger/
S: /u/cvsroot/supermunger/
S: Clear-static-directory supermunger/
S: /u/cvsroot/supermunger/
S: E cvs server: Updating supermunger
S: M U supermunger/mungeall.c
S: Created supermunger/
S: /u/cvsroot/supermunger/mungeall.c
S: /mungeall.c/1.1///
S: u=rw,g=r,o=r
S: 26
S: int mein () { abort (); }
S: ok
</pre></div>
<p>The current client implementation would break the connection here and make a
new connection for the next command. However, the protocol allows it
to keep the connection open and continue, which is what we show here.
</p>
<p>After the user modifies the file and instructs the client to check it
back in. The client sends arguments to specify the log message and file
to check in:
</p>
<div class="example">
<pre class="example-preformatted">C: Argument -m
C: Argument Well, you see, it took me hours and hours to find
C: Argumentx this typo and I searched and searched and eventually
C: Argumentx had to ask John for help.
C: Argument mungeall.c
</pre></div>
<p>It also sends information about the contents of the working directory,
including the new contents of the modified file. Note that the user has
changed into the <samp class="file">supermunger</samp> directory before executing this
command; the top level directory is a user-visible concept because the
server should print filenames in <code class="code">M</code> and <code class="code">E</code> responses
relative to that directory.
</p>
<div class="example">
<pre class="example-preformatted">C: Directory .
C: supermunger
C: Entry /mungeall.c/1.1///
C: Modified mungeall.c
C: u=rw,g=r,o=r
C: 26
C: int main () { abort (); }
</pre></div>
<p>And finally, the client issues the checkin command (which makes use of
the data just sent):
</p>
<div class="example">
<pre class="example-preformatted">C: ci
</pre></div>
<p>And the server tells the client that the checkin succeeded:
</p>
<div class="example">
<pre class="example-preformatted">S: M Checking in mungeall.c;
S: E /u/cvsroot/supermunger/mungeall.c,v <-- mungeall.c
S: E new revision: 1.2; previous revision: 1.1
S: E done
S: Mode u=rw,g=r,o=r
S: Checked-in ./
S: /u/cvsroot/supermunger/mungeall.c
S: /mungeall.c/1.2///
S: ok
</pre></div>
<hr>
</div>
<div class="section-level-extent" id="Requirements">
<div class="nav-panel">
<p>
Next: <a href="#Obsolete" accesskey="n" rel="next">Obsolete protocol elements</a>, Previous: <a href="#Example" accesskey="p" rel="prev">Example</a>, Up: <a href="#Protocol" accesskey="u" rel="up">The CVS client/server protocol</a> </p>
</div>
<h3 class="section" id="Required-versus-optional-parts-of-the-protocol"><span>5.14 Required versus optional parts of the protocol<a class="copiable-link" href="#Required-versus-optional-parts-of-the-protocol"> ¶</a></span></h3>
<p>The following are part of every known implementation of the CVS protocol
(except obsolete, pre-1.5, versions of CVS) and it is considered
reasonable behavior to completely fail to work if you are connected with
an implementation which attempts to not support them. Requests:
<code class="code">Root</code>, <code class="code">Valid-responses</code>, <code class="code">valid-requests</code>,
<code class="code">Directory</code>, <code class="code">Entry</code>, <code class="code">Modified</code>, <code class="code">Unchanged</code>,
<code class="code">Argument</code>, <code class="code">Argumentx</code>, <code class="code">ci</code>, <code class="code">co</code>, <code class="code">update</code>.
Responses: <code class="code">ok</code>, <code class="code">error</code>, <code class="code">Valid-requests</code>,
<code class="code">Checked-in</code>, <code class="code">Updated</code>, <code class="code">Merged</code>, <code class="code">Removed</code>,
<code class="code">M</code>, <code class="code">E</code>.
</p>
<p>A server need not implement <code class="code">Repository</code>, but in order to interoperate
with CVS 1.5 through 1.9 it must claim to implement it (in
<code class="code">Valid-requests</code>). The client will not actually send the request.
</p>
<hr>
</div>
<div class="section-level-extent" id="Obsolete">
<div class="nav-panel">
<p>
Previous: <a href="#Requirements" accesskey="p" rel="prev">Required versus optional parts of the protocol</a>, Up: <a href="#Protocol" accesskey="u" rel="up">The CVS client/server protocol</a> </p>
</div>
<h3 class="section" id="Obsolete-protocol-elements"><span>5.15 Obsolete protocol elements<a class="copiable-link" href="#Obsolete-protocol-elements"> ¶</a></span></h3>
<p>This section briefly describes protocol elements which are obsolete.
There is no attempt to document them in full detail.
</p>
<p>There was a <code class="code">Repository</code> request which was like <code class="code">Directory</code>
except it only provided <var class="var">repository</var>, and the local directory was
assumed to be similarly named.
</p>
<p>If the <code class="code">UseUnchanged</code> request was not sent, there was a <code class="code">Lost</code>
request which was sent to indicate that a file did not exist in the
working directory, and the meaning of sending <code class="code">Entries</code> without
<code class="code">Lost</code> or <code class="code">Modified</code> was different. All current clients (CVS
1.5 and later) will send <code class="code">UseUnchanged</code> if it is supported.
</p>
<hr>
</div>
</div>
<div class="chapter-level-extent" id="Protocol-Notes">
<div class="nav-panel">
<p>
Previous: <a href="#Protocol" accesskey="p" rel="prev">The CVS client/server protocol</a>, Up: <a href="#Top" accesskey="u" rel="up">CVS Client/Server</a> </p>
</div>
<h2 class="chapter" id="Notes-on-the-Protocol"><span>6 Notes on the Protocol<a class="copiable-link" href="#Notes-on-the-Protocol"> ¶</a></span></h2>
<p>A number of enhancements are possible. Also see the file <small class="sc">TODO</small> in
the <small class="sc">CVS</small> source distribution, which has further ideas concerning
various aspects of <small class="sc">CVS</small>, some of which impact the protocol.
Similarly, the <a class="url" href="http://www.nongnu.org/cvs/">http://www.nongnu.org/cvs/</a> site, in particular the
<cite class="cite">Development</cite> pages.
</p>
<ul class="itemize mark-bullet">
<li>The <code class="code">Modified</code> request could be speeded up by sending diffs rather
than entire files. The client would need some way to keep the version
of the file which was originally checked out; probably requiring the use
of "cvs edit" in this case is the most sensible course (the "cvs edit"
could be handled by a package like VC for emacs). This would also allow
local operation of <code class="code">cvs diff</code> without arguments.
</li><li>The fact that <code class="code">pserver</code> requires an extra network turnaround in
order to perform authentication would be nice to avoid. This relates to
the issue of reporting errors; probably the clean solution is to defer
the error until the client has issued a request which expects a
response. To some extent this might relate to the next item (in terms
of how easy it is to skip a whole bunch of requests until we get to one
that expects a response). I know that the kerberos code doesn’t wait in
this fashion, but that probably can cause network deadlocks and perhaps
future problems running over a transport which is more transaction
oriented than TCP. On the other hand I’m not sure it is wise to make
the client conduct a lengthy upload only to find there is an
authentication failure.
</li><li>The protocol uses an extra network turnaround for protocol negotiation
(<code class="code">valid-requests</code>). It might be nice to avoid this by having the
client be able to send requests and tell the server to ignore them if
they are unrecognised (different requests could produce a fatal error if
unrecognised). To do this there should be a standard syntax for
requests. For example, perhaps all future requests should be a single
line, with mechanisms analogous to <code class="code">Argumentx</code>, or several requests
working together, to provide greater amounts of information. Or there
might be a standard mechanism for counted data (analogous to that used
by <code class="code">Modified</code>) or continuation lines (like a generalised
<code class="code">Argumentx</code>). It would be useful to compare what HTTP is planning
in this area; last I looked they were contemplating something called
Protocol Extension Protocol but I haven’t looked at the relevant IETF
documents in any detail. Obviously, we want something as simple as
possible (but no simpler).
</li><li>The scrambling algorithm in the CVS client and server actually support
more characters than those documented in <a class="ref" href="#Password-scrambling">Password scrambling algorithm</a>.
Someday we are going to either have to document them all (but this is
not as easy as it may look, see below), or (gradually and with adequate
process) phase out the support for other characters in the CVS
implementation. This business of having the feature partly undocumented
isn’t a desirable state long-term.
<p>The problem with documenting other characters is that unless we know
what character set is in use, there is no way to make a password
portable from one system to another. For example, a with a circle on
top might have different encodings in different character sets.
</p>
<p>It <em class="emph">almost</em> works to say that the client picks an arbitrary,
unknown character set (indeed, having the CVS client know what character
set the user has in mind is a hard problem otherwise), and scrambles
according to a certain octet<->octet mapping. There are two problems
with this. One is that the protocol has no way to transmit character 10
decimal (linefeed), and the current server and clients have no way to
handle 0 decimal (NUL). This may cause problems with certain multibyte
character sets, in which octets 10 and 0 will appear in the middle of
other characters. The other problem, which is more minor and possibly
not worth worrying about, is that someone can type a password on one
system and then go to another system which uses a different encoding for
the same characters, and have their password not work.
</p>
<p>The restriction to the ISO646 invariant subset is the best approach for
strings which are not particularly significant to users. Passwords are
visible enough that this is somewhat doubtful as applied here. ISO646
does, however, have the virtue (!?) of offending everyone. It is easy
to say "But the $ is right on people’s keyboards! Surely we can’t
forbid that". From a human factors point of view, that makes quite a
bit of sense. The contrary argument, of course, is that a with a circle
on top, or some of the characters poorly handled by Unicode, are on
<em class="emph">someone</em>’s keyboard.
</p>
</li></ul>
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