Step by Step Modifying Bacula Code

Suppose you want to download Bacula source code, build it, make a change, then submit your change to the Bacula developers. What would you do?

• Tell git who you are:
  

  git config --global user.name "First-name Last-name"
  git config --global user.email "email@address.com"
  

  Where you put your real name and your email address. Since this is global, you only need to do it once on any given machine regardless of how many git repos you work with.

• Download the Source code:
  

  git clone http://git.bacula.org/bacula trunk
  

• Configure and Build Bacula:
  

  ./configure (all-your-normal-options)
  make
  

• Create a branch to work on:

  cd trunk/bacula
  git checkout -b bugfix master
  

• Edit, build, Test, ...
  

  edit file jcr.h
  make
  test
  

  Note: if you forget to create a working branch prior to making changes, and you make them on master, this is no problem providing that you create the working branch before your first commit. So assuming that you have edited master instead of your bugfix branch, you can simply:

  git checkout -b bugfix master
  

  and a new bugfix branch will be created and checked out. You can then proceed to committing to your bugfix branch as described in the next step.

• commit your work:

  git commit -am "Short comment on what I did"
  

• Possibly repeat the above two items

• Switch back to the master branch:
  

  git checkout master
  

• Pull the latest changes:
  

  git pull
  

• Get back on your bugfix branch:
  

  git checkout bugfix
  

• Merge your changes and correct any conflicts:
  

  git rebase master bugfix
  

• Fix any conflicts:
  You will be notified if there are conflicts. The first thing to do is:

  git diff
  

  This will produce a diff of only the files having a conflict. Fix each file in turn. When it is fixed, the diff for that file will go away.

  For each file fixed, you must do the same as SVN, inform git with:

  git add (name-of-file-no-longer-in-conflict)
  

• When all files are fixed do:

  git rebase --continue
  

• If you find that it is impossible to reconcile the two branches or you made a mistake in correcting and adding files, before you enter the:

  git rebase --continue
  

  you can instead enter:

  git rebase --abort
  

  which will essentially cancel the the original git rebase and reset everything to the beginning with no changes to your bugfix branch.

• When you have completed the rebase and are ready to send a patch, do the following:
  

  git checkout bugfix
  git format-patch -M master
  

  Look at the files produced. They should be numbered 0001-xxx.patch where there is one file for each commit you did, number sequentially, and the xxx is what you put in the commit comment.

• If the patch files are good, send them by email to the developers as attachments.

• Then you can continue working on your code if you want, or start another branch with a new project.

• If you continue working on your bugfix branch, you should do a git rebase master from time to time, and when your changes are committed to the repo, you will be automatically synchronized. So that the next git format-patch will produce only the changes you made since the last format-patch you sent to the developers.

More Details

Normally, you will work by creating a branch of the master branch of your repository, make your modifications, then make sure it is up to date, and finally create format-patch patches or push it to the Source Forge repo. Assuming you call the Bacula repository trunk, you might use the following commands:

cd trunk
git checkout master
git pull 
git checkout -b newbranch master
(edit, ...)
git add <file-edited>
git commit -m "<comment about commit>"
...

When you have completed working on your branch, you will do:

cd trunk
git checkout newbranch  # ensure I am on my branch
git pull                # get latest source code
git rebase master       # merge my code

If you have completed your edits before anyone has modified the repository, the git rebase master will report that there was nothing to do. Otherwise, it will merge the changes that were made in the repository before your changes. If there are any conflicts, Git will tell you. Typically resolving conflicts with Git is relatively easy. You simply make a diff:

git diff

Then edit each file that was listed in the git diff to remove the conflict, which will be indicated by lines of:

<<<<<<< HEAD
text
>>>>>>>>
other text
=====

where text is what is in the Bacula repository, and other text is what you have changed.

Once you have eliminated the conflict, the git diff will show nothing, and you must do a:

git add <file-with-conflicts-fixed>

Once you have fixed all the files with conflicts in the above manner, you enter:

git rebase --continue

and your rebase will be complete.

If for some reason, before doing the -continue, you want to abort the rebase and return to what you had, you enter:

git rebase --abort

Finally to make a set of patch files

git format-patch -M master

When you see your changes have been integrated and pushed to the main repo, you can delete your branch with:

git checkout master
git branch -D newbranch