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Subject: How to get the android source code using Cygwin and Git
Date:    2009/04/27
Updated: 2009/05/21
Updated: 2010/03/30


Table of content:
  1- Goals and Requirements
  2- Getting the code, the simple way
  3- SSH issues
  4- Advanced Tricks


-------------------------
1- Goals and Requirements
-------------------------

This document explains how to checkout the Android source from the git
repositories under Windows.

As stated in development/docs/howto_build_SDK.txt, one can't build the whole
Android source code under Windows. You can only build the SDK tools for
Windows.

There are a number of caveats in checking out the code from Git under Windows. 
This document tries to explain them.

First you will need to meet the following requirements:
- You must have Cygwin installed. But wait! You CANNOT use the latest Cygwin 1.7.
  Instead you MUST use the "legacy Cygwin 1.5" that you can find at this page:

    http://cygwin.org/win-9x.html

  Don't mind the page title, just grab setup-legacy.exe and it will works just fine
  under XP or Vista.

- You must install Cyginw using the "Unix / Binary" mode.
  If you don't do that, git will fail to properly compute some SHA1 keys.

- You need the "git" and "curl" packages to checkout the code.
  If you plan to contribute, you might want to get "gitk" also.

  Note: if you want to build the SDK, check the howto_build_SDK.txt file
  for a list of extra required packages.
  The short summary is that you need at least these:
    autoconf, bison, curl, flex, gcc, g++, git, gnupg, make, mingw-zlib, python, unzip, zip
  and you must avoid the "readline" package.


-----------------------------------
2- Getting the code, the simple way
-----------------------------------

Out of the box, "repo" and "git" will work just fine under Cygwin:

  $ repo init -u git://android.git.kernel.org/platform/manifest.git
  $ repo sync

And you're done. You can build as explained in howto_build_SDK.txt and ignore
the rest of this document.


-------------
3- SSH issues
-------------

If you maintain your own private repository using an SSH server, you might get
some "mux/ssh" errors. In this case try this:

  $ repo init -u ssh://my.private.ssh.repo/platform/manifest.git
  $ export GIT_SSH=ssh
  $ repo sync


------------------
4- Advanced Tricks
------------------

There is one remaining issue with the default repo/git options:

If you plan on contributing, you will notice that even after a fresh "repo
sync" some projects are marked as having modified files. This happens on the
"bionic" and the "external/iptables" project. The issue is that they have files
which have the same name yet differ only by their case-sensitivity. Since the
Windows filesystem is not case-sensitive, this confuses Git.

Solution: we can simply ignore these projects as they are not needed to build
the Windows SDK.

To do this you just need to create a file .repo/local_manifest.xml that
provides a list of projects to ignore:

<?xml version="1.0" encoding="UTF-8"?>
<manifest>
  <remove-project name="platform/external/iptables" />
</manifest>

The other thing we can do is tell git not to track the files that cause
problems:

  cd bionic
  git update-index --assume-unchanged \
    libc/kernel/common/linux/netfilter/xt_CONNMARK.h \
    libc/kernel/common/linux/netfilter/xt_MARK.h \
    libc/kernel/common/linux/netfilter_ipv6/ip6t_HL.h

  cd external/tcpdump;
  git update-index --assume-unchanged \
    tests/print-X.new \
    tests/print-XX.new


Here's a script that takes care of all these details. It performs the repo
init, creates the appropriate local_manifest.xml, does a repo sync as
needed and tell git to ignore the offending files:

------------
#!/bin/bash

set -e  # fail on errors

URL=ssh://android-git.corp.google.com:29418/platform/manifest.git
BRANCH=donut
if [ "$1" == "-b" ]; then shift; BRANCH=$1; shift; fi

# repo init if there's no .repo directory
if [[ ! -d .repo ]]; then
    repo init -u $URL -b $BRANCH
fi

# create a local_manifest to exclude projects that cause problems under Windows
# due to the case-insenstivines of the file system.
L=.repo/local_manifest.xml
if [[ ! -f $L ]]; then

    cat > $L <<EOF
<?xml version="1.0" encoding="UTF-8"?>
<manifest>
<remove-project name="platform/external/iptables" />
</manifest>
EOF
fi

# sync using the native ssh client if necessary
[[ $URL != ${URL/ssh/} ]] && export GIT_SSH=ssh
repo sync $@


# These files cause trouble too, we need to ignore them
(cd bionic;
git update-index --assume-unchanged \
    libc/kernel/common/linux/netfilter/xt_CONNMARK.h \
    libc/kernel/common/linux/netfilter/xt_MARK.h \
    libc/kernel/common/linux/netfilter_ipv6/ip6t_HL.h
)
(cd external/tcpdump;
git update-index --assume-unchanged \
    tests/print-X.new \
    tests/print-XX.new
)
------------

Simply extract this to a "my_sync.sh" file and try the following:
  $ mkdir android_src
  $ cd android_src
  $ chmod +x mysync.sh
  $ ./mysync.sh


-end-