Working with Git

This page describes conventions and best practices applicable to the Fedora Git repository.

Line endings

All text files must be normalized so that lines terminate in the unix style (LF). Please do not commit files that terminate in CRLF!

Configuring git to enforce LF normalization

There are several way to enforce LF normalization. Each method carries some consequences, and the consequences & methods differ between versions of Git.

`autocrlf` property

Normalization rules for all text files can be addressed by the 'autocrlf' configuration property. There are two useful values for this property, depending on your platform

autocrlf = input. Use on unix-like platforms. This will perform no conversion upon checkout, but will normalize any crlf files upon commit.
autocrlf = true. Use only on Windows platforms. This will have the effect of converting all text files into dos-style (CRLF) in the working copy upon checkout. Upon commit, all files will be normalized to LF on their way into the repository, but remain in CRLF in the local working copy directory.

This property can be set globally for all local git repositories, or locally for a single git repository.

The autocrlf property can be set globally via the command line. For example:

git config --global core.autocrlf input

Executing this command is identical to editing your ~/.gitconfig file and adding:

[core]
        autocrlf=input

Quick Start Guide for Developers/Committers

Get the repository:

git clone git@github.com:fcrepo/fcrepo.git
cd fcrepo

Create the branch where you'll do your work:
```
git branch fcrepo-780
git checkout fcrepo-780
```
The checkout command makes whatever branch you specify the local active branch. Make your changes, test...
Add your edited/new files, then commit your branch:
```
git add myfile.java
git commit myfile.java
```
Push the branch back up to github
```
git push origin fcrepo-780
```
Merge the branch into master (formerly known as 'trunk')
```
git checkout master
git merge fcrepo-780
```
Resolve any conflicts, and test again.

If any time has passed since you cloned master from github and merged your branch into your local copy of master, make sure that you also merge any upstream changes to master into your local copy:
```
git fetch origin master
```
Examine the changes:
```
git diff origin master
```
then:
```
git merge origin/master
```
(The command git pull does a combined fetch-and-merge, but read this on why that's a bad idea.)

Merges are automatically committed locally.
Update master on github
```
git push origin master
```
Once you've received word that the build has completed correctly, delete the branch
```
git push origin :fcrepo-780
```

You can run git status at any time to get a snapshot of your current state. You can also examine your differences with the master branch on github at any time by executing these two commands:

git fetch origin master
git diff origin master

The autocrlf property can also be set locally for a given git repository, such as the local clone of the fcrepo. For example, from within the local working directory:

git config core.autocrlf input

Executing this command is identical to editing the .git/config file within the git working directory and adding:

[core]
        autocrlf=input

`.gitattributes` file

The presence of a committed .gitattributes file within the code can also be used to apply line-ending rules. This has the benefit of being part of the managed sources (and this part of a given branch, tag, etc), but is not understood by all versions of git. The fedora master branch has a .gitattributes file containing

Unknown macro: {* text=auto}

, which instructs git to detect text files, and normalize to LF at each commit.

Git 1.7.1 and earlier

Earlier versions of git do not understand the necessary directives in .gitattributes file, so autocrlf is the only way to assure compliance with the LF normanlization. Thus

Unix and mac users should set autocrlf = input either globally or locally
Windows users should set autocrlf = auto either globally or locally.

These versions of git may apply/detect autocrlf settings to all files in the working copy immediately. Thus, if checking out older branches/tags/commits that still have crlf files in the repository, these files will be seen as automatically 'modified' when doing a 'git status'. This may have confusing side-effects.

Git 1.7.2+

These versions of git heed the .gitattributes directive, so it is not strictly necessary to set autocrlf, but it is recommended.

These versions of git will apply the autocrlf setting to new files - preventing the introduction of non-normalized crlf files into the repository, but ignoring existing crlf files.