1 \input texinfo @c -*- texinfo -*-
3 @settitle Using git to develop Libav
6 @center @titlefont{Using git to develop Libav}
15 This document aims in giving some quick references on a set of useful git
16 commands. You should always use the extensive and detailed documentation
17 provided directly by git:
24 shows you the available subcommands,
31 shows information about the subcommand <command>.
33 Additional information could be found on the
34 @url{http://gitref.org, Git Reference} website
36 For more information about the Git project, visit the
38 @url{http://git-scm.com/, Git website}
40 Consult these resources whenever you have problems, they are quite exhaustive.
42 What follows now is a basic introduction to Git and some Libav-specific
43 guidelines to ease the contribution to the project
49 You can get git from @url{http://git-scm.com/}
50 Most distribution and operating system provide a package for it.
53 @section Cloning the source tree
56 git clone git://git.libav.org/libav.git <target>
59 This will put the Libav sources into the directory @var{<target>}.
62 git clone git@@git.libav.org:libav.git <target>
65 This will put the Libav sources into the directory @var{<target>} and let
66 you push back your changes to the remote repository.
68 Make sure that you do not have Windows line endings in your checkouts,
69 otherwise you may experience spurious compilation failures. One way to
70 achieve this is to run
73 git config --global core.autocrlf false
77 @section Updating the source tree to the latest revision
83 pulls in the latest changes from the tracked branch. The tracked branch
84 can be remote. By default the master branch tracks the branch master in
88 Since merge commits are forbidden @command{--rebase} (see below) is recommended.
91 @section Rebasing your local branches
97 fetches the changes from the main repository and replays your local commits
98 over it. This is required to keep all your local changes at the top of
99 Libav's master tree. The master tree will reject pushes with merge commits.
102 @section Adding/removing files/directories
105 git add [-A] <filename/dirname>
106 git rm [-r] <filename/dirname>
109 GIT needs to get notified of all changes you make to your working
110 directory that makes files appear or disappear.
111 Line moves across files are automatically tracked.
114 @section Showing modifications
117 git diff <filename(s)>
120 will show all local modifications in your working directory as unified diff.
123 @section Inspecting the changelog
126 git log <filename(s)>
129 You may also use the graphical tools like gitview or gitk or the web
130 interface available at http://git.libav.org/
132 @section Checking source tree status
138 detects all the changes you made and lists what actions will be taken in case
139 of a commit (additions, modifications, deletions, etc.).
148 to double check your changes before committing them to avoid trouble later
149 on. All experienced developers do this on each and every commit, no matter
151 Every one of them has been saved from looking like a fool by this many times.
152 It's very easy for stray debug output or cosmetic modifications to slip in,
153 please avoid problems through this extra level of scrutiny.
155 For cosmetics-only commits you should get (almost) empty output from
158 git diff -w -b <filename(s)>
161 Also check the output of
167 to make sure you don't have untracked files or deletions.
170 git add [-i|-p|-A] <filenames/dirnames>
173 Make sure you have told git your name and email address
176 git config --global user.name "My Name"
177 git config --global user.email my@@email.invalid
180 Use @var{--global} to set the global configuration for all your git checkouts.
182 Git will select the changes to the files for commit. Optionally you can use
183 the interactive or the patch mode to select hunk by hunk what should be
191 Git will commit the selected changes to your current local branch.
193 You will be prompted for a log message in an editor, which is either
194 set in your personal configuration file through
197 git config --global core.editor
200 or set by one of the following environment variables:
201 @var{GIT_EDITOR}, @var{VISUAL} or @var{EDITOR}.
203 Log messages should be concise but descriptive. Explain why you made a change,
204 what you did will be obvious from the changes themselves most of the time.
205 Saying just "bug fix" or "10l" is bad. Remember that people of varying skill
206 levels look at and educate themselves while reading through your code. Don't
207 include filenames in log messages, Git provides that information.
209 Possibly make the commit message have a terse, descriptive first line, an
210 empty line and then a full description. The first line will be used to name
211 the patch by git format-patch.
213 @section Preparing a patchset
216 git format-patch <commit> [-o directory]
219 will generate a set of patches for each commit between @var{<commit>} and
220 current @var{HEAD}. E.g.
223 git format-patch origin/master
226 will generate patches for all commits on current branch which are not
228 A useful shortcut is also
234 which will generate patches from last @var{n} commits.
235 By default the patches are created in the current directory.
237 @section Sending patches for review
240 git send-email <commit list|directory>
243 will send the patches created by @command{git format-patch} or directly
244 generates them. All the email fields can be configured in the global/local
245 configuration or overridden by command line.
246 Note that this tool must often be installed separately (e.g. @var{git-email}
247 package on Debian-based distros).
250 @section Renaming/moving/copying files or contents of files
252 Git automatically tracks such changes, making those normal commits.
255 mv/cp path/file otherpath/otherfile
261 @chapter Git configuration
263 In order to simplify a few workflows, it is advisable to configure both
264 your personal Git installation and your local Libav repository.
266 @section Personal Git installation
268 Add the following to your @file{~/.gitconfig} to help @command{git send-email}
269 and @command{git format-patch} detect renames:
276 @section Repository configuration
278 In order to have @command{git send-email} automatically send patches
279 to the libav-devel mailing list, add the following stanza
280 to @file{/path/to/libav/repository/.git/config}:
284 to = libav-devel@@libav.org
287 @chapter Libav specific
289 @section Reverting broken commits
295 @command{git reset} will uncommit the changes till @var{<commit>} rewriting
296 the current branch history.
302 allows to amend the last commit details quickly.
305 git rebase -i origin/master
308 will replay local commits over the main repository allowing to edit, merge
309 or remove some of them in the process.
312 @command{git reset}, @command{git commit --amend} and @command{git rebase}
313 rewrite history, so you should use them ONLY on your local or topic branches.
314 The main repository will reject those changes.
321 @command{git revert} will generate a revert commit. This will not make the
322 faulty commit disappear from the history.
324 @section Pushing changes to remote trees
330 Will push the changes to the default remote (@var{origin}).
331 Git will prevent you from pushing changes if the local and remote trees are
332 out of sync. Refer to and to sync the local tree.
335 git remote add <name> <url>
338 Will add additional remote with a name reference, it is useful if you want
339 to push your local branch for review on a remote host.
342 git push <remote> <refspec>
345 Will push the changes to the @var{<remote>} repository.
346 Omitting @var{<refspec>} makes @command{git push} update all the remote
347 branches matching the local ones.
349 @section Finding a specific svn revision
351 Since version 1.7.1 git supports @var{:/foo} syntax for specifying commits
352 based on a regular expression. see man gitrevisions
355 git show :/'as revision 23456'
358 will show the svn changeset @var{r23456}. With older git versions searching in
359 the @command{git log} output is the easiest option (especially if a pager with
360 search capabilities is used).
361 This commit can be checked out with
364 git checkout -b svn_23456 :/'as revision 23456'
367 or for git < 1.7.1 with
370 git checkout -b svn_23456 $SHA1
373 where @var{$SHA1} is the commit hash from the @command{git log} output.
376 @chapter pre-push checklist
378 Once you have a set of commits that you feel are ready for pushing,
379 work through the following checklist to doublecheck everything is in
380 proper order. This list tries to be exhaustive. In case you are just
381 pushing a typo in a comment, some of the steps may be unnecessary.
382 Apply your common sense, but if in doubt, err on the side of caution.
384 First make sure your Git repository is on a branch that is a direct
385 descendant of the Libav master branch, which is the only one from which
386 pushing to Libav is possible. Then run the following command:
389 @item @command{git log --patch --stat origin/master..}
391 to make sure that only the commits you want to push are pending, that
392 the log messages of the commits are correct and descriptive and contain
393 no cruft from @command{git am} and to doublecheck that the commits you
394 want to push really only contain the changes they are supposed to contain.
396 @item @command{git status}
398 to ensure no local changes still need to be committed and that no local
399 changes may have thrown off the results of your testing.
402 Next let the code pass through a full run of our testsuite. Before you do,
403 the command @command{make fate-rsync} will update the test samples. Changes
404 to the samples set are not very common and commits depending on samples
405 changes are delayed for at least 24 hours to allow the new samples to
406 propagate, so updating it once per day is sufficient. Now execute
409 @item @command{make distclean}
410 @item @command{/path/to/libav/configure}
411 @item @command{make check}
414 While the test suite covers a wide range of possible problems, it is not
415 a panacea. Do not hesitate to perform any other tests necessary to convince
416 yourself that the changes you are about to push actually work as expected.
418 Also note that every single commit should pass the test suite, not just
419 the result of a series of patches. So if you have a series of commits
420 to push, run the test suite on every single commit.
422 Give other developers a reasonable amount of time to look at and review
423 patches before you push them. Not everybody is online 24/7, but may wish
424 to look at and comment on a patch nonetheless. The time you leave depends
425 on the urgency and complexity of the patch. Use your common sense to pick
426 a timeframe that allows everybody that you think may wish to comment
427 and/or should comment on the change an opportunity to see it.
429 Finally, after pushing, mark all patches as committed on
430 @url{http://patches.libav.org/,patchwork}.
431 Sometimes this is not automatically done when a patch has been
432 slightly modified from the version on the mailing list.
433 Also update previous incarnations of the patches you push so that
434 patchwork is not cluttered with cruft.
437 @chapter Server Issues
439 Contact the project admins @email{git@@libav.org} if you have technical
440 problems with the GIT server.