----------------------------------------------------------------------
                   Notes for Freeciv packagers
----------------------------------------------------------------------

This file is meant to help those people wanting to package Freeciv
for their distribution, and, to some degree, those people who want to
create Freeciv fork.

----------------------------------------------------------------------
Updating from 2.4 to 2.5
------------------------
* Client uses ~/.freeciv-client-rc-2.5 for storing its options.
  Options are always saved to that file.
  Loading of options first tries to get options from
  ~/.freeciv-client-rc-2.5. If that file does not exist it tries to
  load options from old client files generated by former version of Freeciv
  (e.g. ~/.freeciv-client-rc-2.4 generated by Freeciv 2.4 or ~/.civclientrc
   generated by Freeciv version <= 2.1).
* Threads are now hard requirement. Supported threading systems
  are pthreads and Windows threads
* It's possible to build both gtk2 and gtk3 based modpack installers
  simultaneously with --enable-fcmp=gtk2,gtk3. Name of the produced
  binaries are freeciv-mp-gtk2 and freeciv-mp-gtk3 instead of old
  freeciv-modpack.
* Qt-based version of modpack installer has been added. You can build
  it with configure option --enable-fcmp=qt (or e.g. --enable-fcmp=gtk3,qt).
  Resulting binary is called freeciv-mp-qt.
* Command line version modpack installer has been added. You can build
  it with configure option --enable-fcmp=cli (or e.g. --enable-fcmp=gtk3,cli)
  Resulting binary is called freeciv-mp-cli.
* Name of the default ruleset is no longer "default" but it's renamed as
  "classic" Some files default to all rulesets still reside in data/default,
  files specific to classic ruleset in new data/classic directory
* Minimum version of readline is 4.3. Readline support cannot be enabled
  with older versions.
* It's possible to build freeciv to use SDL2_mixer (SDL 2) instead of
  SDL_mixer (SDL 1.2) by giving configure option --enable-sdl-mixer=sdl2
* SDL-client depends on SDL_gfx and SDL_ttf instead of containing copies
  of their code in itself
* AI module "threaded" is usable. For most part it just uses same code
  "classic" module uses, so there's not much difference between the two.
* New configure option --with-missinglist to see what features have been
  automatically left out due to missing dependencies.
* Lua5.2 is now used. If you are using --enable-sys-lua, provide
  lua5.2 instead of lua5.1 in your system.
* New configure option --without-freeciv-manual to disable build
  of freeciv-manual tool that's mostly useless for normal users.
* Qt-client is now supported client, no longer just "in-development"
* Xaw-client is no longer considered maintained client
* Minimum libcurl version is now 7.12.1

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Compatibility of modified versions
----------------------------------
If you create patched version of Freeciv, take necessary precautions
to avoid problems when your patched version interacts with unpatched
version, or tries to load or save incompatible data files.

Concept called "capabilities" is widely used in Freeciv. If two things
(server/client, program/datafile...) are incompatible, they have
different capabilities defined. Based on that they can detect
incompatibility and act gracely.
Be sure to update network capability string in fc_version if you break
network compatibility, so your patched server/client does not cause
problems to official Freeciv servers/clients trying to connect it.

If you distribute modified version of freeciv, even (or especially)
one network compatible with upstream, you should change also
FREECIV_DISTRIBUTOR in fc_version to match. This information is sent
by client to (public) server so in case there's any problems with certain
clients, we know a bit more what kind of code they are using.

----------------------------------------------------------------------
Announcement of new versions
----------------------------
As of 2.4, the Freeciv client displays the latest available version if
it's newer than the running version. This information comes from the
metaserver.

The metaserver maintains several different versions to report here,
distinguished by "follow tags". The default follow tag is "stable",
updated when a new source release is made, but for instance Windows
builds will follow a different tag such as "win32", which will only be
updated when a new Windows binary is available.

This mechanism is primary intended for the Freeciv maintainers, since
updates to the metaserver need to be made be us. However, if you
maintain a significant version/package of Freeciv, you can contact us
and ask to be allocated a tag to pass to 'configure --with-followtag';
thereafter you'd need to let us know whenever you make a new release
so we can update the metaserver.

(This is unlikely to be of use to Linux distribution packagers, who
have their own means of distributing updates.)

----------------------------------------------------------------------
Optional features
-----------------
Configure enables many optional features by default when their
dependencies are satisfied in the system. Downside of this automation
is that missing dependencies cause no hard error even when you would
want the features. For getting list of features automatically left out
because of missing dependencies you can give option --with-missinglist
to configure, and last thing configure outputs will be that list.

----------------------------------------------------------------------
Shared libfreeciv
-----------------
Libfreeciv contains code common to server and client. By default it's
built as static library, but you can build it as shared library by
giving configure option "--enable-shared" (and possibly "--disable-static")

----------------------------------------------------------------------
Generated files
---------------
This is list of files Freeciv might generate to filesystem when running.
You may want to remove some of these when Freeciv is uninstalled.

* Client saves its options to file "~/.freeciv-client-rc-2.5"
* Server saves its readline history to file "~/.freeciv-server_history"
* When running local single player games, challenge files with name
  like "~/.freeciv/challenge_*_*" are generated
* When saving game in server launched by client, savegame go to
  "~/.freeciv/saves/"
* When saving game in independently launched server, savegames go
  to directory specified with "-s" command line option, defaulting
  to working directory
* freeciv-modpack saves data under "~/.freeciv/2.5/" and
  "~/.freeciv/scenarios/"
* Server can write log to file specified with "-l" command line option
* When mapimage feature is used, it can save colortest images to
  working directory and actual map images to save directory (same as above)

----------------------------------------------------------------------
Building multiple clients at once
---------------------------------
Starting from 2.2 it has been possible to build multiple clients running
'make' just once. Just give configure option "--enable-client" comma
separated list of clients to compile, e.g. "--enable-client=gtk3,gtk2,sdl,qt"

----------------------------------------------------------------------
Savegame compression support
----------------------------
Freeciv can use several different compression libraries for compressing
its savegames. See server setting "compresstype".
* zlib (gzip compression) is required to compile freeciv so zlib
  compression support is always present
* bzip2 compression is built into Freeciv if bzip2 libraries and
  headers are present at configure time
* xz compression is built into Freeciv if liblzma library and
  headers are present at configure time

While this feature is called "Savegame compression support" it actually
applies to loading of all the section files: savegames, rulesets, tileset
spec files... If compression support is built into Freeciv, you can
compress any of these files and Freeciv can still load them. Freeciv ships
with all the data files uncompressed, except scenarios which are gzipped.

----------------------------------------------------------------------
Loadable AI modules
-------------------
Freeciv can be built with support of loading AI code from custom module.
There can be multiple modules loaded at once, and AI players can use
different module from each other.
This feature is not enabled by default. When it's not enabled, default
AI code is built in to server and always used.
You can enable this feature with '--enable-aimodules'. For this to work
you have to enable also building of shared libraries (and modules) with
'--enable-shared' as discussed in chapter 'Shared libfreeciv'
All modules, both default and custom, must be installed under
${libdir}/fcai (/usr/lib/fcai for example) for their loading to work.

----------------------------------------------------------------------
Public servers
--------------
Sadly we have not resources to keep public servers for many different
Freeciv versions running. To give your users ability to play on public
servers, try to provide them as current Freeciv client version as possible.
To see list of currently running public servers, see
"http://meta.freeciv.org/metaserver.php" Note that from the web you
can see complete list, while list shown by Freeciv client only lists
compatible servers.

Any a.b.c release is network compatible with any a.b.d release. If you
provide 2.5.c client, it can be used to play on 2.5.d server.
