Git Wine Tutorial

From WineHQ Wiki
(Redirected from GitWine)
Jump to: navigation, search

Welcome to the Git Wine tutorial! This page describes how to manage Wine code and patches with Git. Git is a fast version control system, originally written for use with large repositories, such as the Linux Kernel source. The Git Wine tree gives you fast access to the entire Wine tree and its history, and allows you to maintain a local tree or patch series and merge it easily with WineHQ.

Tutorials and guides

Note: To get documentation on a Git command, use `git help` or `man`. For example, the following two commands are equivalent:

git help format-patch
man git-format-patch

Set up your Git repository

The first step to using Git with Wine is to set up a local Git repository.

Downloading and installing Git

It's recommended to install Git via your distribution's package manager. If you want to install from source, you can download the latest version of Git from https://www.kernel.org/pub/software/scm/git/ . It installs into ~/bin by default. See the Pro Git book for build instructions.

Cloning the Wine Git repository

You can browse the WineHQ Git repositories on the web at https://source.winehq.org/git. To download the main Wine repository:

git clone git://source.winehq.org/git/wine.git
cd wine

If you are stuck behind an uncooperative firewall, try cloning from https://github.com/wine-mirror/wine.git instead.

The clone operation transfers around 150 MiB of data. If all goes well, the output of git config remote.origin.url should be:

$ git config remote.origin.url
git://source.winehq.org/git/wine.git

and you will have a single branch named "master", which can be revealed by running git branch.

Further configuration

If you plan on sharing or committing any patches at all, you should set your name and email address using:

git config --global user.name "Your Name"
git config --global user.email "me@example.com"

A useful feature of Git is its ability to color the output of various commands (diff, status, branch, etc). To enable colors in all commands that support it, when running them from a terminal:

git config --global color.ui auto

Particularly useful is the colored output of the git diff command, as it also highlights trailing whitespace in patches.

Glossary

See also the official Git glossary.

  • A commit (or changeset, or revision) is a snapshot of a codebase. Each commit has a name -- its commit id -- which is a SHA1 hash. Commits can have other names (tags, etc). See the "Specifying revisions" section of the git rev-parse page for details on how refer to commits. The verb to commit means to create a commit.
  • A diff is a file describing the differences between two sets of files. They are created with the command git diff. If you have code in the "before" state, you can apply the patch (with git apply) and you end up with code in the "after" state.
  • A patch is a file that includes authorship information, a description, and a diff. They are created with git format-patch and committed with git am. This similar to applying a patch, but it also creates a commit that preserves the original description and authorship information.
  • The HEAD (or tip) of a branch is the most recent commit. On its own, HEAD means the tip of the current branch.
  • master is the main branch. SVN/CVS calls this "trunk".
  • The parent of a commit is the one before it in the history. (Commits can technically have more than one parent, but the Wine repo avoids using this feature, preferring a linear history.) Given a commit `X`, its parent is referred to as `X^`, and its great-grandparent is referred to as `X^^^` or `X~3`.
  • A repository (or repo) is a database storing the source code of every available version of a program, and the author of every change.
  • A tree is a git technical term meaning "directory" (sort of), and sometimes means the whole codebase of a project ("the Wine tree").
  • The working copy or working tree refers to the files and directories on your file system, the ones you can see and change with the file manager. The git status command will refer to changes to these files as "Changed but not updated".

Managing your changes - the simple way

Committing a change into your local tree

After editing the checked out tree, you can use git status to see which files have changed:

git status

Or you can examine the difference by using git diff:

git diff

To then commit all changed files to your local tree, use the git commit command with the -a option:

git commit -a

If you only wish to commit some files, use:

git commit <file1> <file2>

or:

git add <file1> <file2>...
git commit

Commit early, commit often: Your local Git tree is yours. You should feel free to commit patches frequently, as it's not until you mail them in that they have a chance of being committed upstream.

Seeing where you are and what you've done

You can get a list of all the commits in the tree using git whatchanged or git log:

git whatchanged     # list of commits, which shows what files were altered
git log             # list of commits
git log --decorate  # list of commits, with the last upstream commit marked
git log --stat      # list of commits, with diffstats
git log --stat -p   # list of commits, with diffstats and patches

You can get a list of files that you have changed but have not yet committed using git status:

git status          # list of uncommitted changes

There's a nice tool to view your Git repository named gitk, written in tcl/tk. AJ suggests using something like `gitk wine-1.0..` to make it go faster (please note that the trailing `..` is important). gitk visualizes both committed and uncommitted changes.

qgit also provides similar functionality, but in a Qt based interface. It appears to be faster than gitk and has additional features such as an annotation facility to identify which change introduced each line of a file.

If you prefer using your terminal, "git lol" and "git lola" are useful aliases you can add to your ~/.gitconfig file:

[alias]
	lol = log --graph --decorate --pretty=oneline --abbrev-commit
	lola = log --graph --decorate --pretty=oneline --abbrev-commit --all

If you have a webserver running, git instaweb allows you to view your local tree in your web browser.

Reverting changes in your working copy

If you have edited some files, but decided you don't like the changes you've made and want to undo all the changes that you've made to your working copy, you can use git checkout:

git checkout -f             # revert everything
git checkout file-name      # revert one file

Alternatively, use git reset:

git reset --hard HEAD       # revert everything

Undoing commits

If you want to undo your most recent commit, you can use the git reset command:

git reset HEAD^          # undo commit, but keep changes to working files
git reset --hard HEAD^   # undo commit, and reset working files as well
git reset --hard HEAD~5  # undo 5 commits
git reset --hard origin  # scrap all changes and start all over again

Editing commits

To edit the most recent commit:

vi file.c                        # edit the file
git commit --amend file.c        # redo the commit

To edit earlier commits (or reorder or delete them) use the -i (aka --interactive) option to git rebase. So if you are interested in altering the 5 most recent commits use:

git rebase -i HEAD~5

This will open your editor, with a list of commits prefixed with pick. To delete a commit, just remove its line. To reorder them, just rearrange the lines. To edit commits, change pick to edit.

Be sure to follow the instructions carefully when doing git-rebase -i. Specifically, when you are editing a commit (that you explicitly requested to edit) and are satisfied with the changes, you must use:

git add <file1> <file2>...
git commit --amend
git rebase --continue

However, when `git-rebase -i` asks you to edit a commit that you have not requested to edit (e.g. there is a conflict), you must use:

git add file1 file2...
git rebase --continue

This is quite important - not following this carefully will result in merged patches.

Editing commits the hard way

Instructions for those who don't want to use git rebase -i:

If the commit is not the most recent one, but say 5th from the top then you can:

git checkout -b tmp HEAD~5              # rewind to the commit in question
vi file.c                               # edit the file
git commit --amend file.c               # redo the commit without deleting the commit
git rebase --onto tmp master~5 master   # replay the later changes
git branch -D tmp                       # clean up the temporary branch

Where there are a number of files to amend you are probably better off using:

git checkout -b tmp HEAD~5              # rewind to the commit in question
git reset HEAD^                         # delete the commit at the now current point
vi file1.c                              # edit
vi file2.c                              #      the files
git commit -a -c ORIG_HEAD              # redo the commit incorporating all changed files
git rebase --onto tmp master~5 master   # replay the later changes
git branch -D tmp                       # clean up the temporary branch

Where the commit is not the most recent one, but say 5th from the top and you wish to insert a new commit, then you can:

git checkout -b tmp HEAD~5              # rewind to the commit in question
vi new_file.c                           # create the new file
git commit -m "New commit of file new_file.c" new-file.c # create a new commit or a series of commits
git rebase --onto tmp master~5 master   # replay the later changes
git branch -D tmp                       # clean up the temporary branch

Likewise if you want to delete a commit that is not the most recent one, then you can:

git checkout -b tmp HEAD~5              # rewind to the commit in question
git reset HEAD^                         # delete the commit at the now current point
git checkout path/file1 path/file2 etc  # delete the changed files
git rebase --onto tmp master~5 master   # replay the later changes
git branch -D tmp                       # clean up the temporary branch

and the commit is gone. You need to checkout all the changed files though and the rebase may throw some errors for you to resolve as it applies later commits.

Removing trailing whitespace

Thank you to Mike Kaplinskiy for this very helpful hint:

git rebase --whitespace=fix origin/master

"It fixes whitespace on all the commits that you've made. I think it's pretty good about merge conflicts due to whitespace as well. I don't know of a way of doing this at commit time though."

This is essential for submitting your patches to the Wine project. Please see this post for more information: https://www.winehq.org/pipermail/wine-devel/2010-July/084870.html

Trailing whitespace is highlighted in the output of the git diff command when colored output is enabled (more about this in the Further configuration section).

Keeping up to date with WineHQ

Now that you have a copy of the Wine Git repository, you will periodically need to receive new commits from the original repository. You do this using:

git pull --rebase

This is equivalent to:

git fetch
git rebase origin

git fetch retrieves new files from the WineHQ Git repository; this should always be a safe operation as it does not change your local file system.

git rebase origin reapplies any local commits you have made onto the latest WineHQ branch. (Technically, it creates a new branch on 'origin', reapplies all the patches in your current HEAD to the new branch, then changes HEAD to the new branch.) Patches already applied upstream will not be reapplied.

A common mistake is to use `git fetch` by itself. It will only download updates but will not apply them. Another common problem is trying to rebase while having uncommitted changes. One way to fix this is to:

git commit -a         # commit changes
git rebase origin     # rebase
git reset HEAD^       # uncommit changes

When you send patches, inevitably, some of your patches will be rejected, while others will be accepted. If you have written a series of patches, but only some of those are rejected, it can be annoying to reorder them, fix one or two problems and resubmit. The main git tools that you can use to help solve this problem are git rebase and git cherry-pick. See here for a discussion on the Git mailing list about rebasing on local branches.

Resolving merge conflicts

When rebasing, sometimes upstream changes prevent your patches from applying. If there is a conflict, you will see something like this:

Applying <patchname>
error: patch failed: <file>:<line>
error: <file>: patch does not apply
Using index info to reconstruct a base tree...
Falling back to patching base and 3-way merge...
Auto-merged <file>
CONFLICT (content): Merge conflict in <file>
Failed to merge in the changes.
Patch failed at <msgnum>.
When you have resolved this problem run "git rebase --continue".
If you would prefer to skip this patch, instead run "git rebase --skip".
To restore the original branch and stop rebasing run "git rebase --abort".

There are two choices now: resolve the conflict or skip the patch. The file in question will contain conflict markers where the patch failed:

<<<<<<<
[code that caused patch not to be applied]
=======
[what would have been here if the patch had been applied]
>>>>>>>

To resolve the conflict you have to manually merge the code between the conflict markers, leaving the file in a compilable state. After that, run

git add <file>
git rebase --continue

to remove the merge-conflict state and continue with the operation.

Patches can be skipped as follows:

(git reset --hard  # removes the patch)
git rebase --skip

Sending patches: generating a patchset

After checking in your local changes (in multiple small commits), you can generate a list of the patches you need to send upstream (i.e. to wine-patches) with the git format-patch command:

git format-patch origin

"origin" is short for "origin/master", the default name of the upstream WineHQ branch. One file per patch will be created in the current directory. You can change the output directory with `-o <directory>`, for example `-o out` to save the patches in the out directory.

You can also add `--subject-prefix=""` to avoid getting the word `PATCH` in all your email subjects (i.e. `[PATCH x/y]`).

Important: If you have not read it already, please read SubmittingPatches.

Adding a cover letter

Passing the `--cover-letter` option to `git format-patch` allows you to create a "patch 0" that describes the patchset. This first "patch file" contains no actual changes, but can be easily sent as an email before the real patches.

Sending the patches using SMTP

Before you can use the `git send-email` command, you have to add information about your SMTP server to ~/.gitconfig. For example, if you are sending from Gmail, put:

[sendemail]
	smtpencryption = tls
	smtpserver = smtp.gmail.com
	smtpuser = yourname@gmail.com
	smtpserverport = 587

You can then send the patches with the command:

git send-email *.patch

If you want to check your patches first (e.g. to alter the subject line), just use the `--annotate` option to `git send-email`.

Sending the patches using IMAP

You should be able to put patches directly into an IMAP drafts folder using git imap-send.

git format-patch --stdout origin | git imap-send

Set up the IMAP server by editing wine/.git/config and adding entries something like this:

[user]
	name = "Your Name Here"
	email = "your@email.here.com"
[imap]
	folder = "INBOX.Drafts"
	tunnel = "ssh -C -q user@imapserver.net /usr/bin/imapd ./Maildir 2> /dev/null"
[format]
	headers = "To: wine-patches <wine-patches@winehq.org>\n"

The above works for Courier IMAP; for Dovecot, change the [imap] section to something like this:

[imap]
	host   = dummy
	folder = "Drafts"
	tunnel = "ssh user@dovecotserver.net /usr/libexec/dovecot/imap  2> /dev/null"

If you would like to send patches directly to your Drafts folder on gmail, change the [imap] section to something like the following:

[imap]
	folder = "[Gmail]/Drafts"
	host = imaps://imap.gmail.com
	user = user
	pass = pass
	port = 993
	sslverify = false

Using Mozilla, sending patches is then just a matter of clicking on "Edit Draft", reviewing the mail and then clicking "Send". If you're using Evolution, you can drag and drop the .patch files into your drafts folder. Patches in the Drafts folder will have the date and time of the timestamp of the commit, hence if you generate multiple times you will have many copies of the same patch with the same date and time. This will be the case until you amend the commit and get a new commit timestamp.

Important: Many email clients will alter your email in ways that will prevent them from applying. For example, Thunderbird will wrap emails and send them with 'format=flowed', which will make them unusable by Git. For Thunderbird, you can follow these instructions to send patches. If all else fails, you can add `--attach` to the `git format-patch` command to send the emails as attachments. Setting up ssh simplifies the patch generation by removing the need to enter a password. Use ssh-keygen to create your keys and copy ~/.ssh/id_rsa.pub to ~/.ssh/authorized_keys to allow the tunnel to be created without entering a password.

Using local Thunderbird folders, you can use the following approach to add your patches to the Drafts folder (without using IMAP):

git format-patch --stdout --attach origin | formail -ds >>"/home/username/.thunderbird/12345678.default/Mail/Local Folders/Drafts"

Note: Sometimes you have to rebuild the index of the Drafts folder in Thunderbird to see the mails added this way.

Using local KMail folders, you can use the following approach:

git format-patch --stdout origin | formail -s procmail

Assuming you don't already use procmail to sort your email, you can use the following .procmailrc

:0
/home/username/.maildir/

Now, all you need to do is to set up a new receiving account in KMail that collects mail from /home/username/.maildir and filter emails coming in on that account to your drafts folder.

Managing branches

Git branches can be useful if you are working on a lot of bugs at the same time. However, they are completely optional and overkill if you are only working on one thing.

Creating a branch

To create a branch, use git checkout with the -b option. For example:

git checkout -b new-branch HEAD~5

This winds back the working directory to HEAD~5, and forks the history there, creating the branch new-branch. The new branch becomes the current branch.

Navigating branches

Use git branch to list all branches.

git branch              # local branches only
git branch -a           # both local and remote branches

To change branches, use git checkout:

git checkout master     # change to branch master

Merging and rebasing branches

Git allows you to merge branches together; this is not done in the WineHQ repository, so it is easier to just rebase/cherry-pick instead.

Deleting branches

git branch -D new-branch

Advanced branching

For more information on managing branches in git, see the Git Branches page.

Other useful operations

Picking patches from another branch

You can cherry pick (apply) a patch from another branch into your current branch using:

git cherry-pick <commit-id>

This will create a new commit, but with authorship information from the original patch.

Getting rid of timestamp changes

Git considers a file changed if its date is different from that in the Git index file. "git diff-index HEAD" may show files have changed if you have edited them and reverted the changes (or even just touched the file). You can remove this difference using:

git reset

Regression testing

Regression testing is really easy with Git. It's done with the help of git bisect that does all the magic. So all that's left to do is to compile and test. Even non-developers can do it. See Regression Testing for instructions.

Committer statistics

To see a list of committers in the last 5 years, sorted by number of commits:

git shortlog -s -n --since="(5years)"

Finding who changed what

git log /path/           # log of changes to files in /path/
git log /path/file       # log of changes to /path/file
git blame /path/file     # show per-line authorship info
git blame -w /path/file  # ditto, but ignoring whitespace changes

Working with GitHub

Introduction

GitHub, through its ability to "fork" an existing project, provides a good way to work on the Wine project when, for example, the project itself is in "code freeze" due to proximity to a release milestone.

You will find the WineHQ repository on a !GitHub mirror.

To fork, simply register. Once registered, click on the Fork button in the upper right hand side of the Wine repository link above.

Once you have forked

You will find helpful information on forking a project at !GitHub.

Once forking is complete, you will find an SSH URL listed, that has read/write access, of the form:

git@github.com:username/wine.git

First, you must check out your new repository. To do so, type:

git clone git@github.com:username/wine.git

It is advantageous to add the WineHQ Git repository as an upstream repository, rather than the !GitHub mirror. Additionally, we will rebase with this repository to ensure that the HEAD of our repository is up to date with WineHQ. To do this, use the following commands:

git remote add upstream git://source.winehq.org/git/wine.git
git pull --rebase upstream

to include the upstream (main) Wine repository as a "remote" in your fork.

Once you have made some local changes, committed them locally, and want to commit them to your !GitHub fork, use the following command:

git push origin master

Finally, to update your local branch to match your !GitHub repository, use:

git pull --rebase

Useful morsels

Output all your patches in the directory out:

git format-patch -o out upstream/master

Save all your patches as one big file (for your own easy reference/viewing):

git log upstream/master..origin -p > /path/to/file 2>&1

Count the number of patches in your repository but not in upstream Wine (useful for keeping track of any disappearing patches):

git rev-list upstream/master..origin | wc -l

Perform an interactive rebase of your commits using git rebase:

git rebase -i upstream/master

Finally, if you would like to force commits onto !GitHub (e.g. edited patches), use:

git push -f origin master

Personally, I (MishaKoshelev) use the following each time I have some new patches that I would like to send to my !GitHub repository. This ensures that all patches are forced, and trailing whitespace is removed:

git fetch
git rebase --whitespace=fix upstream/master
git push -f origin master

Patch stack

Stacked Git is similar to Quilt, just on top of Git. It manages a stack of applied and unapplied patches on top of a Git branch. Patches can be pushed on the applied stack or popped off the applied stack onto the unapplied stack. The topmost applied patch can be edited and the stack can be rebased onto an updated branch. This makes keeping around and refining local changesets (changeset->patch) until they are applied upstream much easier. The history of changes to a patch are also kept in Git.

Annoyances

It can be quite hard to get a real understanding of the underlying concepts of Git, and if you are a git newb you are almost certain to run into in a situation where things break and you have no idea how to get out of the mess. At this point: don't panic! You might be tempted to just trash your repository and manually remerge your patches, but it is very probable you will run into the same situation again so you'd be better off making sure you have understood how Git works. Look through the list of tutorials at the top of this page.

Other Git repositories

Branch URL Branch Description
https://source.winehq.org/git/wine.git Standard Wine repository
https://github.com/wine-compholio/wine-staging Wine Staging repository
https://source.winehq.org/git/website.git WineHQ website (https://winehq.org/)
https://source.winehq.org/git/tools.git Tools used on the WineHQ website
https://source.winehq.org/git/appdb.git AppDB website (https://appdb.winehq.org/)
https://source.winehq.org/git/bugzilla.git Bugzilla website (https://bugs.winehq.org/)
http://git.etersoft.ru/projects/?p=wine/eterwine.git Contains versions of Wine used by Etersoft for running programs under Linux