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  12 <title>cvs2svn Features</title>
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  18 <h1>cvs2svn Features</h1>
  19
  20 <p>The primary goal of cvs2svn is to migrate as much information as
  21 possible from your old CVS repository to your new Subversion or git
  22 repository.</p>
  23
  24 <p>Unfortunately, CVS doesn't record complete information about your
  25 project's history.  For example, CVS doesn't record what file
  26 modifications took place together in the same CVS commit.  Therefore,
  27 cvs2svn attempts to infer from CVS's incomplete information what
  28 <em>really</em> happened in the history of your repository.  So the
  29 second goal of cvs2svn is to reconstruct as much of your CVS
  30 repository's history as possible.</p>
  31
  32 <p>The third goal of cvs2svn is to allow you to customize the
  33 conversion process and the form of your output repository as flexibly
  34 as possible.  cvs2svn has very many conversion options that can be
  35 used from the command line, many more that can be configured via an
  36 options file, and provides many hooks to allow even more extreme
  37 customization by writing Python code.</p>
  38
  39 <h2><a name="list">Feature summary</a></h2>
  40
  41 <dl>
  42
  43   <dt>No information lost</dt>
  44   <dd>cvs2svn works hard to avoid losing any information from your CVS
  45     repository (unless you specifically ask for a partial conversion
  46     using <tt>--trunk-only</tt> or <tt>--exclude</tt>).</dd>
  47
  48   <dt>Changesets</dt>
  49   <dd>CVS records modifications file-by-file, and does not keep track
  50     of what files were modified at the same time.  cvs2svn uses
  51     information like the file modification times, log messages, and
  52     dependency information to deduce the original changesets.  cvs2svn
  53     allows changesets that affect multiple branches and/or multiple
  54     projects (as is allowed by CVS), or it can be configured to split
  55     such changesets up into separate commits
  56     (<tt>--no-cross-branch-commits</tt>; see also options file).</dd>
  57
  58   <dt>Multiproject conversions</dt>
  59   <dd>cvs2svn can convert a CVS repository that contains multiple
  60     projects into a single Subversion repository with the conventional
  61     multiproject directory layout.  See <a
  62     href="faq.html#onetoone">the FAQ</a> for more information.</dd>
  63
  64   <dt>Branch vs. tag</dt>
  65   <dd>CVS allows the same symbol name to be used sometimes as a
  66     branch, sometimes as a tag.  cvs2svn has options and heuristics to
  67     decide how to convert such "mixed" symbols
  68     (<tt>--symbol-hints</tt>, <tt>--force-branch</tt>,
  69     <tt>--force-tag</tt>, <tt>--symbol-default</tt>).</dd>
  70
  71   <dt>Branch/tag exclusion</dt>
  72   <dd>cvs2svn allows the user to specify branches and/or tags that
  73     should be excluded from the conversion altogether
  74     (<tt>--symbol-hints</tt>, <tt>--exclude</tt>).  It checks that the
  75     exclusions are self-consistent (e.g., it doesn't allow a branch to
  76     be excluded if a branch that sprouts from it is not excluded).</dd>
  77
  78   <dt>Branch/tag renaming</dt>
  79   <dd>cvs2svn can rename branches and tags during the conversion using
  80     regular-expression patterns (<tt>--symbol-transform</tt>).</dd>
  81
  82   <dt>Choosing SVN paths for branches/tags</dt>
  83   <dd>You can choose what SVN paths to use as the trunk/branches/tags
  84     directories (<tt>--trunk</tt>, <tt>--branches</tt>,
  85     <tt>--tags</tt>), or set arbitrary paths for specific CVS
  86     branches/tags (<tt>--symbol-hints</tt>).  For example, you might
  87     want to store some tags to the <tt>project/tags</tt> directory,
  88     but others to <tt>project/releases</tt>.</dd>
  89
  90   <dt>Branch and tag parents</dt>
  91   <dd>In many cases, the CVS history is ambiguous about which branch
  92     served as the parent of another branch or tag.  cvs2svn determines
  93     the most plausible parent for symbols using cross-file
  94     information.  You can override cvs2svn's choices on a case-by-case
  95     basis by using the <tt>--symbol-hints</tt> option.</dd>
  96
  97   <dt>Branch and tag creation times</dt>
  98   <dd>CVS does not record when branches and tags are created.  cvs2svn
  99     creates branches and tags at a reasonable time, consistent with
 100     the file revisions that were tagged, and tries to create each one
 101     within a single Subversion commit if possible.</dd>
 102
 103   <dt>Mime types</dt>
 104   <dd>CVS does not record files' mime types.  cvs2svn provides several
 105     mechanisms for choosing reasonable file mime types
 106     (<tt>--mime-types</tt>, <tt>--auto-props</tt>).</dd>
 107
 108   <dt>Binary vs. text</dt>
 109   <dd>Many CVS users do not systematically record which files are
 110     binary and which are text.  (This is mostly important if the
 111     repository is used on non-Unix systems.)  cvs2svn provides a
 112     number of ways to infer this information
 113     (<tt>--eol-from-mime-type</tt>, <tt>--default-eol</tt>,
 114     <tt>--keywords-off</tt>, <tt>--auto-props</tt>).</dd>
 115
 116   <dt>Subversion file properties</dt>
 117   <dd>Subversion allows arbitrary text properties to be attached to
 118     files.  cvs2svn provides a mechanism to set such properties when a
 119     file is first added to the repository
 120     (<tt>--auto-props</tt>) as well as a hook that users can use to
 121     set arbitrary file properties via Python code.</dd>
 122
 123   <dt>Handling of <tt>.cvsignore</tt></dt>
 124   <dd><tt>.cvsignore</tt> files in the CVS repository are converted
 125     into the equivalent <tt>svn:ignore</tt> properties in the output.
 126     By default, the <tt>.cvsignore</tt> files themselves are
 127     <em>not</em> included in the output; this behavior can be changed
 128     by specifying the <tt>--keep-cvsignore</tt> option.</dd>
 129
 130   <dt>Subversion repository customization</dt>
 131   <dd>cvs2svn provides many options that allow you to customize the
 132     structure of the resulting Subversion repository
 133     (<tt>--trunk</tt>, <tt>--branches</tt>, <tt>--tags</tt>,
 134     <tt>--include-empty-directories</tt>, <tt>--no-prune</tt>,
 135     <tt>--symbol-transform</tt>, etc.; see also the additional
 136     customization options available by using the <a
 137     href="#options-file-method"><tt>--options</tt>-file
 138     method</a>).</dd>
 139
 140   <dt>Support for multiple character encodings</dt>
 141   <dd>CVS does not record which character encoding was used to store
 142     metainformation like file names, author names and log messages.
 143     cvs2svn provides options to help convert such text into UTF-8
 144     (<tt>--encoding</tt>, <tt>--fallback-encoding</tt>).</dd>
 145
 146   <dt>Vendor branches</dt>
 147   <dd>CVS supports "vendor branches", which (under some circumstances)
 148     affect the contents of the main line of development.  cvs2svn
 149     detects vendor branches whenever possible and handles them
 150     intelligently.  For example,
 151     <ul>
 152
 153       <li>cvs2svn explicitly copies vendor branch revisions back to
 154         trunk so that a checkout of trunk gives the same results under
 155         SVN as under CVS.</li>
 156
 157       <li>If a vendor branch is excluded from the conversion, cvs2svn
 158         grafts the relevant vendor branch revisions onto trunk so that
 159         the contents of trunk are still the same as in CVS.  If other
 160         tags or branches sprout from these revisions, they are grafted
 161         to trunk as well.</li>
 162
 163       <li>When a file is imported into CVS, CVS creates two revisions
 164         ("1.1" and "1.1.1.1") with the same contents.  cvs2svn
 165         discards the redundant "1.1" revision in such cases (since
 166         revision "1.1.1.1" will be copied to trunk anyway).</li>
 167
 168       <li>Often users create vendor branches unnecessarily by using
 169         "cvs import" to import their own sources into the CVS
 170         repository.  Such vendor branches do not contain any useful
 171         information, so by default cvs2svn excludes any vendor branch
 172         that was only used for a single import.  You can change this
 173         default behavior by specifying the
 174         <tt>--keep-trivial-imports</tt> option.</li>
 175
 176     </ul>
 177
 178   </dd>
 179
 180   <dt>CVS quirks</dt>
 181   <dd>cvs2svn goes to great length to deal with CVS's many quirks.
 182     For example,
 183     <ul>
 184
 185       <li>CVS introduces spurious "1.1" revisions when a file is added
 186         on a branch.  cvs2svn discards these revisions.</li>
 187
 188       <li>If a file is added on a branch, CVS introduces a spurious
 189         "dead" revision at the beginning of the branch to indicate
 190         that the file did not exist when the branch was created.
 191         cvs2svn deletes these spurious revisions and adds the file on
 192         the branch at the correct time.</li>
 193
 194     </ul>
 195   </dd>
 196
 197   <dt>Robust against repository corruption</dt>
 198   <dd>cvs2svn knows how to handle several types of CVS repository
 199     corruption that have been reported frequently, and gives
 200     informative error messages in other cases:
 201     <ul>
 202
 203       <li>An RCS file that exists both in and out of the "Attic"
 204         directory.</li>
 205
 206       <li>Multiple deltatext blocks for a single CVS file
 207         revision.</li>
 208
 209       <li>Multiple revision headers for the same CVS file
 210         revision.</li>
 211
 212       <li>Tags and branches that refer to non-existent revisions or
 213         ill-formed revision numbers.</li>
 214
 215       <li>Repeated definitions of a symbol name to the same revision
 216         number.</li>
 217
 218       <li>Branches that have no associated labels.</li>
 219
 220       <li>A directory name that conflicts with a file name (in or out
 221         of the Attic).</li>
 222
 223       <li>Filenames that contain forbidden characters.</li>
 224
 225       <li>Log messages with variant end-of-line styles.</li>
 226
 227       <li>Vendor branch declarations that refer to non-existent
 228         branches.</li>
 229
 230     </ul>
 231   </dd>
 232
 233   <dt>Timestamp error correction</dt>
 234   <dd>Many CVS repositories contain timestamp errors due to servers'
 235     clocks being set incorrectly during part of the repository's
 236     history.  cvs2svn's history reconstruction is relatively robust
 237     against timestamp errors and it writes monotonic timestamps to the
 238     Subversion repository.</dd>
 239
 240   <dt>Scalable</dt>
 241   <dd>cvs2svn stores most intermediate data to on-disk databases so
 242     that it can convert very large CVS repositories using a reasonable
 243     amount of RAM.  Conversions are organized as multiple passes and
 244     can be restarted at an arbitrary pass in the case of
 245     problems.</dd>
 246
 247   <dt>Configurable/extensible using Python</dt>
 248   <dd>Many aspects of the conversion can be customized using Python
 249     plugins that interact with cvs2svn through documented interfaces
 250     (<tt>--options</tt>).</dd>
 251
 252 </dl>
 253
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