Netlabs CVS README
(W) Ulrich Mller, November 12, 1999
Last updated February 10, 2007 by Paul Ratcliffe


0. CONTENTS OF THIS FILE
========================

    1. INTRODUCTION TO CVS
    2. WHICH CVS VERSION TO USE
    3. SETUP
    4. CVS CONCEPTS
    5. CHECKING OUT THE CODE


0. ABOUT THIS DOCUMENT
======================

    This is for people who would like to access the XWorkplace
    source code. If you have never written a C program before,
    you will probably not be interested in this document.


1. INTRODUCTION TO CVS
======================

    CVS stands for "Concurrent Versioning System". It is a tool
    which allows several developers to work on the same source code
    at the same time.

    For those of you that have never dealt with anything like this...
    just imagine a word processor document on a shared network
    directory that several people work on at the same time. There
    has to be some coordination of all the changes going on and
    checks whether the changes conflict with each other.

    CVS does exactly that, except that it can handle large directory
    trees with many files of any type -- text or binary.

    The concept of a client/server CVS setup is that the server
    maintains a "repository" with the entire source code, including
    all changes that were ever made. Each developer then creates a
    local copy of the sources on his hard disk. So each developer
    can safely work on the local sources until he thinks that
    everyone else should get the changes (once they're halfway
    stable), and can then put the changes on the server, and all
    other developers can then update their local copy.

    While your local copy will always be at a certain code/revision
    level (and only updated from the server if you request this),
    the server maintains all changes that were ever made. You can,
    for example, even retrieve the sources in the state were in in
    the middle of 1999, if you want.

    Maybe the nicest thing about CVS is that with text files, it can
    merge code changes. CVS has GNU "diff" built in so even if two
    people work on the same source file, CVS in most cases can
    automatically keep the changes in sync. See "Terminology" below.

    Netlabs has set up a CVS server on which all the Netlabs projects
    reside. This document should give you all the information about
    how to access that repository.


2. WHICH CVS VERSION TO USE
===========================

    CVS is a Unix program that was ported to OS/2. At the time of
    writing, there are several CVS versions on Hobbes. I strongly
    recommend you use 1.12.13, which is the most bug-free of them all.


3. SETUP
========

    You can use the Netlabs Open Source Archive Client (NOSAC)
    instead of running CVS from the command line. However, I have
    found the command line much more practical, so I am going to
    explain the basics here. Please refer to the CVS documentation
    for details.

    As with most Unix programs, CVS expects you to have a "home"
    directory. If you don't have one, create an empty directory
    somewhere and set the HOME environment variable to that directory.

    In any case, I strongly recommend to create a file in $(HOME)
    called ".cvsrc" and add put a single line

        cvs -z3

    in there to enable some compression during transfers. This
    greatly speeds up things if you have a slow internet connection.
    Otherwise CVS will do all network transfers with uncompressed
    data, which can be terribly slow.

    Secondly, the most practical way to use CVS is to have a common
    parent directory for all code repositories (i.e. projects). So
    create one (for example, "F:\cvs"), which will become the parent
    directory for all CVS projects (e.g. "F:\cvs\xworkplace",
    "F:\cvs\warpin", "F:\cvs\xwphelpers"). If you later check out
    repositories from sources other than Netlabs (e.g. from
    SourceForge), they can go into this root as well.

    Finally, CVS needs you to have a user name and a password. If you
    don't have one yet, use "guest" and "readonly", which will give
    you read-only access to all Netlabs projects. (Other servers will
    have different conventions here.)

    Set the current project environment. This is done via another
    environment variable, so for XWorkplace, set:

        CVSROOT=:pserver:guest@cvs.netlabs.org:/netlabs.cvs/xworkplace

    For WarpIN, use:

        CVSROOT=:pserver:guest@cvs.netlabs.org:/netlabs.cvs/warpin

    For the "XWorkplace helpers", which are needed by both XWorkplace
    and WarpIN, use:

        CVSROOT=:pserver:guest@cvs.netlabs.org:/netlabs.cvs/xwphelpers

    and so on. Currently, Netlabs holds over a dozen projects which
    can all be retrieved that way.

    NOTE: The CVSROOT path was changed in February 2002 for all Netlabs
    projects. From your old CVSROOT variables, simply remove the "e:"
    before "/netlabs.cvs". You will need to run "cvs login" again to
    have CVS pick up the change (see below).

    Create a local subdirectory in your CVS root directory with the
    same name (e.g. ("F:\cvs\xworkplace"). Change to that directory.

    Set USER=guest in your environment. Fire up your internet connection.
    To log onto a project, use the "cvs login" command. Enter "readonly"
    when you are prompted for the password. (Note that you will need to
    enter "cvs login" separately for each repository. CVS will then store
    the data in $(HOME)\.cvspass so you only need to do this once per project.)

    You are now ready to download ("check out") a project. See section
    5 below.


4. CVS TERMINOLOGY
==================

    The following terms should be known when working with CVS (or
    even reading the documentation):

    -- "Repository" is the unit CVS uses for managing projects.
       For example, "xworkplace", "warpin", and "xwphelpers" are
       three repositories on the Netlabs CVS server. Repositories
       are mirrored locally in a subdirectory of your CVS root
       directory, if you followed the above setup.

       Repositories are usually equivalent to projects. However,
       repositories are just a directory on the server and can be
       created in any way. For example, we created the "xwphelpers"
       repository for code that is shared between XWorkplace and
       WarpIN.

    -- "Checkout": "Checking out" code means that you retrieve (or
       update) a local copy of files in a repository. You can check
       out an entire repository or single files from it.

       To check out code, use the "cvs checkout" command. Details
       follow in the next section.

    -- "Commit": If you have write access to the CVS server (which
       requires that you have been given a user name and password
       by the Netlabs admin, Adrian Gschwend), you can change the
       repository by "committing" your local copy back onto the
       server. Once the code has been committed, all other developers
       can check it out again and will have the updates.

       To commit code to the server, use the "cvs commit" command.
       See the CVS reference for details. Again, this requires that
       you have been granted write access by the server administrator.

       Usually, with most projects, only a limited number of people
       have write access to the server, for obvious reasons. But
       this is a "project policy" issue and not a CVS restriction.

    -- "Merge": This can happen if you have checked out your local
       copy of a repository already and do another "checkout" later.

       If CVS then finds that a file has been changed on the server
       and your local copy needs to be updated, it "merges" all
       changes into the local copy. That is, it does not simply
       overwrite the local copy with the new version on the server,
       but will compare (diff) the two files and patch the local
       copy! As a result, you will not lose changes you made to
       your local copy when you check out updates.

       CVS has GNU "diff" built in for this, so this is pretty
       powerful.

       This happens automatically if you do "cvs checkout" after
       your initial checkout. Note that you can also use
       "cvs update"; the difference is that "update" will not
       retrieve new files, but only update existing local files.
       See the CVS reference for details.

    -- "Conflicts": This happens if CVS cannot successfully merge
       changes into your local copy. Most frequently, this occurs
       when two developers have modified the same lines in the
       same source file. Of course, CVS cannot resolve these
       conflicts by itself, so it will put two versions into the
       file marked with special characters. (With C files, this
       will cause compilation to fail, which is intentional so
       that you have to manually resolve the conflict.)

       See the CVS reference for details.


5. CHECKING OUT THE CODE
========================

    Change to the XWorkplace root directory (e.g. "F:\cvs\xworkplace")
    set the XWorkplace environment as described above (HOME, USER,
    CVSROOT), and log on if you haven't logged on yet.

    The command for getting source from the server is "cvs checkout".
    With checkout, you need to specify the module to check out. For
    the purpose of this explanation, we will consider a "module" a
    directory name. Note that CVS normally operates on directories
    recursively! So if you use

        cvs checkout .

    (mind the dot) from the XWorkplace root directory, this will
    retrieve the entire code tree and create new local files if
    they don't exist yet. This can take a while for bigger projects.
    Again, use maximum compression (see section 3).

    "cvs checkout" allows you to specify file masks as well. For
    example, if you type

        cvs checkout src/shared/*.c

    only those files are checked out. Mind the forward slashes.

    By contrast, "cvs update" only updates local files which have
    been changed on the server. It does not create new files.
    Since I frequently create new files on the server, using
    "checkout" will probably be the better general choice.

    Note that to compile XWorkplace, you will also need the
    "XWorkplace Helpers" code, which is in a separate repository
    called "xwphelpers". So create a new empty project directory
    (e.g. "F:\cvs\xwphelpers"), change CVSROOT to point to the
    "xwphelpers" repository, change to the new directory, and
    do a "cvs checkout ." again.

    You will see that CVS puts out lots of information about the
    files that were worked on. A typical CVS output from "update"
    or "checkout" looks like this:

        ? doc/progref.ipf
        M makefile
        M include/build.h
        M include/filesys/program.h
        M src/classes/xcenter.c

    I strongly recommend redirecting standard output when using
    "cvs update" or "checkout" so you know what CVS has done,
    since these lines scroll of the screen very quickly. You
    can simply use "cvs checkout . > checkout.log". An even
    better choice is "tee", another GNU program, which prints
    the output to the screen and logs it in a file at the same
    time.

    In each such line, the first letter tells you what CVS has
    done to the file:

        ?: CVS does not know the file. It is in your local tree,
           but not in the repository.
           This happens if you have added files to your local copy
           yourself.

        U: This is the most frequent one. It means that CVS has
           "U"pdated a local file with a new copy from the server
           and occurs during "checkout" or "update".

        P: Similar to "U", except that the server has only sent
           a "P"atch instead of the entire file. The result isn't
           any different from "U"; the file has been updated.

        M: This means that your local file was "M"odified before the
           update. You get this no matter if the file was updated
           (i.e. changes were merged successfully) or not.

        C: This happens if merge failed and a "C"onflict occurred.
           You need to manually edit all files which have been
           marked with "C"; if they are C source files, they will
           no longer compile.

        R: A local file has been removed because it is no longer
           in the repository (i.e. has been removed by someone
           with write access).

