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1 | My First Contribution to the Git Project |
2 | ======================================== | |
5ef811ac | 3 | :sectanchors: |
76644e32 | 4 | |
5ef811ac | 5 | [[summary]] |
76644e32 ES |
6 | == Summary |
7 | ||
8 | This is a tutorial demonstrating the end-to-end workflow of creating a change to | |
9 | the Git tree, sending it for review, and making changes based on comments. | |
10 | ||
5ef811ac | 11 | [[prerequisites]] |
76644e32 ES |
12 | === Prerequisites |
13 | ||
14 | This tutorial assumes you're already fairly familiar with using Git to manage | |
15 | source code. The Git workflow steps will largely remain unexplained. | |
16 | ||
5ef811ac | 17 | [[related-reading]] |
76644e32 ES |
18 | === Related Reading |
19 | ||
20 | This tutorial aims to summarize the following documents, but the reader may find | |
21 | useful additional context: | |
22 | ||
23 | - `Documentation/SubmittingPatches` | |
24 | - `Documentation/howto/new-command.txt` | |
25 | ||
4bb4fd42 ES |
26 | [[getting-help]] |
27 | === Getting Help | |
28 | ||
29 | If you get stuck, you can seek help in the following places. | |
30 | ||
a2dc4341 ES |
31 | ==== git@vger.kernel.org |
32 | ||
33 | This is the main Git project mailing list where code reviews, version | |
34 | announcements, design discussions, and more take place. Those interested in | |
35 | contributing are welcome to post questions here. The Git list requires | |
36 | plain-text-only emails and prefers inline and bottom-posting when replying to | |
37 | mail; you will be CC'd in all replies to you. Optionally, you can subscribe to | |
af3d2c16 JH |
38 | the list by sending an email to <git+subscribe@vger.kernel.org> |
39 | (see https://subspace.kernel.org/subscribing.html for details). | |
40 | The https://lore.kernel.org/git[archive] of this mailing list is | |
a2dc4341 ES |
41 | available to view in a browser. |
42 | ||
4bb4fd42 ES |
43 | ==== https://groups.google.com/forum/#!forum/git-mentoring[git-mentoring@googlegroups.com] |
44 | ||
a2dc4341 ES |
45 | This mailing list is targeted to new contributors and was created as a place to |
46 | post questions and receive answers outside of the public eye of the main list. | |
47 | Veteran contributors who are especially interested in helping mentor newcomers | |
48 | are present on the list. In order to avoid search indexers, group membership is | |
49 | required to view messages; anyone can join and no approval is required. | |
4bb4fd42 | 50 | |
91d23470 | 51 | ==== https://web.libera.chat/#git-devel[#git-devel] on Libera Chat |
4bb4fd42 ES |
52 | |
53 | This IRC channel is for conversations between Git contributors. If someone is | |
54 | currently online and knows the answer to your question, you can receive help | |
55 | in real time. Otherwise, you can read the | |
56 | https://colabti.org/irclogger/irclogger_logs/git-devel[scrollback] to see | |
57 | whether someone answered you. IRC does not allow offline private messaging, so | |
58 | if you try to private message someone and then log out of IRC, they cannot | |
59 | respond to you. It's better to ask your questions in the channel so that you | |
60 | can be answered if you disconnect and so that others can learn from the | |
61 | conversation. | |
62 | ||
5ef811ac | 63 | [[getting-started]] |
76644e32 ES |
64 | == Getting Started |
65 | ||
5ef811ac | 66 | [[cloning]] |
76644e32 ES |
67 | === Clone the Git Repository |
68 | ||
69 | Git is mirrored in a number of locations. Clone the repository from one of them; | |
70 | https://git-scm.com/downloads suggests one of the best places to clone from is | |
71 | the mirror on GitHub. | |
72 | ||
73 | ---- | |
74 | $ git clone https://github.com/git/git git | |
2656fb16 | 75 | $ cd git |
76644e32 ES |
76 | ---- |
77 | ||
3ada78de ES |
78 | [[dependencies]] |
79 | === Installing Dependencies | |
80 | ||
81 | To build Git from source, you need to have a handful of dependencies installed | |
82 | on your system. For a hint of what's needed, you can take a look at | |
83 | `INSTALL`, paying close attention to the section about Git's dependencies on | |
84 | external programs and libraries. That document mentions a way to "test-drive" | |
85 | our freshly built Git without installing; that's the method we'll be using in | |
86 | this tutorial. | |
87 | ||
88 | Make sure that your environment has everything you need by building your brand | |
89 | new clone of Git from the above step: | |
90 | ||
91 | ---- | |
92 | $ make | |
93 | ---- | |
94 | ||
95 | NOTE: The Git build is parallelizable. `-j#` is not included above but you can | |
96 | use it as you prefer, here and elsewhere. | |
97 | ||
5ef811ac | 98 | [[identify-problem]] |
76644e32 ES |
99 | === Identify Problem to Solve |
100 | ||
101 | //// | |
102 | Use + to indicate fixed-width here; couldn't get ` to work nicely with the | |
103 | quotes around "Pony Saying 'Um, Hello'". | |
104 | //// | |
105 | In this tutorial, we will add a new command, +git psuh+, short for ``Pony Saying | |
106 | `Um, Hello''' - a feature which has gone unimplemented despite a high frequency | |
107 | of invocation during users' typical daily workflow. | |
108 | ||
109 | (We've seen some other effort in this space with the implementation of popular | |
110 | commands such as `sl`.) | |
111 | ||
5ef811ac | 112 | [[setup-workspace]] |
76644e32 ES |
113 | === Set Up Your Workspace |
114 | ||
115 | Let's start by making a development branch to work on our changes. Per | |
116 | `Documentation/SubmittingPatches`, since a brand new command is a new feature, | |
117 | it's fine to base your work on `master`. However, in the future for bugfixes, | |
118 | etc., you should check that document and base it on the appropriate branch. | |
119 | ||
120 | For the purposes of this document, we will base all our work on the `master` | |
121 | branch of the upstream project. Create the `psuh` branch you will use for | |
122 | development like so: | |
123 | ||
124 | ---- | |
125 | $ git checkout -b psuh origin/master | |
126 | ---- | |
127 | ||
128 | We'll make a number of commits here in order to demonstrate how to send a topic | |
129 | with multiple patches up for review simultaneously. | |
130 | ||
5ef811ac | 131 | [[code-it-up]] |
76644e32 ES |
132 | == Code It Up! |
133 | ||
134 | NOTE: A reference implementation can be found at | |
135 | https://github.com/nasamuffin/git/tree/psuh. | |
136 | ||
5ef811ac | 137 | [[add-new-command]] |
76644e32 ES |
138 | === Adding a New Command |
139 | ||
140 | Lots of the subcommands are written as builtins, which means they are | |
141 | implemented in C and compiled into the main `git` executable. Implementing the | |
142 | very simple `psuh` command as a built-in will demonstrate the structure of the | |
143 | codebase, the internal API, and the process of working together as a contributor | |
144 | with the reviewers and maintainer to integrate this change into the system. | |
145 | ||
146 | Built-in subcommands are typically implemented in a function named "cmd_" | |
147 | followed by the name of the subcommand, in a source file named after the | |
148 | subcommand and contained within `builtin/`. So it makes sense to implement your | |
149 | command in `builtin/psuh.c`. Create that file, and within it, write the entry | |
150 | point for your command in a function matching the style and signature: | |
151 | ||
152 | ---- | |
153 | int cmd_psuh(int argc, const char **argv, const char *prefix) | |
154 | ---- | |
155 | ||
156 | We'll also need to add the declaration of psuh; open up `builtin.h`, find the | |
24c68179 PS |
157 | declaration for `cmd_pull`, and add a new line for `psuh` immediately before it, |
158 | in order to keep the declarations alphabetically sorted: | |
76644e32 ES |
159 | |
160 | ---- | |
161 | int cmd_psuh(int argc, const char **argv, const char *prefix); | |
162 | ---- | |
163 | ||
6b79a218 JS |
164 | Be sure to `#include "builtin.h"` in your `psuh.c`. You'll also need to |
165 | `#include "gettext.h"` to use functions related to printing output text. | |
76644e32 | 166 | |
6b79a218 JS |
167 | Go ahead and add some throwaway printf to the `cmd_psuh` function. This is a |
168 | decent starting point as we can now add build rules and register the command. | |
76644e32 ES |
169 | |
170 | NOTE: Your throwaway text, as well as much of the text you will be adding over | |
171 | the course of this tutorial, is user-facing. That means it needs to be | |
172 | localizable. Take a look at `po/README` under "Marking strings for translation". | |
173 | Throughout the tutorial, we will mark strings for translation as necessary; you | |
174 | should also do so when writing your user-facing commands in the future. | |
175 | ||
176 | ---- | |
177 | int cmd_psuh(int argc, const char **argv, const char *prefix) | |
178 | { | |
179 | printf(_("Pony saying hello goes here.\n")); | |
180 | return 0; | |
181 | } | |
182 | ---- | |
183 | ||
24c68179 | 184 | Let's try to build it. Open `Makefile`, find where `builtin/pull.o` is added |
76644e32 ES |
185 | to `BUILTIN_OBJS`, and add `builtin/psuh.o` in the same way next to it in |
186 | alphabetical order. Once you've done so, move to the top-level directory and | |
187 | build simply with `make`. Also add the `DEVELOPER=1` variable to turn on | |
188 | some additional warnings: | |
189 | ||
190 | ---- | |
191 | $ echo DEVELOPER=1 >config.mak | |
192 | $ make | |
193 | ---- | |
194 | ||
195 | NOTE: When you are developing the Git project, it's preferred that you use the | |
196 | `DEVELOPER` flag; if there's some reason it doesn't work for you, you can turn | |
197 | it off, but it's a good idea to mention the problem to the mailing list. | |
198 | ||
76644e32 ES |
199 | Great, now your new command builds happily on its own. But nobody invokes it. |
200 | Let's change that. | |
201 | ||
202 | The list of commands lives in `git.c`. We can register a new command by adding | |
203 | a `cmd_struct` to the `commands[]` array. `struct cmd_struct` takes a string | |
204 | with the command name, a function pointer to the command implementation, and a | |
205 | setup option flag. For now, let's keep mimicking `push`. Find the line where | |
206 | `cmd_push` is registered, copy it, and modify it for `cmd_psuh`, placing the new | |
24c68179 | 207 | line in alphabetical order (immediately before `cmd_pull`). |
76644e32 ES |
208 | |
209 | The options are documented in `builtin.h` under "Adding a new built-in." Since | |
210 | we hope to print some data about the user's current workspace context later, | |
211 | we need a Git directory, so choose `RUN_SETUP` as your only option. | |
212 | ||
213 | Go ahead and build again. You should see a clean build, so let's kick the tires | |
214 | and see if it works. There's a binary you can use to test with in the | |
215 | `bin-wrappers` directory. | |
216 | ||
217 | ---- | |
218 | $ ./bin-wrappers/git psuh | |
219 | ---- | |
220 | ||
221 | Check it out! You've got a command! Nice work! Let's commit this. | |
222 | ||
2656fb16 ES |
223 | `git status` reveals modified `Makefile`, `builtin.h`, and `git.c` as well as |
224 | untracked `builtin/psuh.c` and `git-psuh`. First, let's take care of the binary, | |
24c68179 | 225 | which should be ignored. Open `.gitignore` in your editor, find `/git-pull`, and |
2656fb16 ES |
226 | add an entry for your new command in alphabetical order: |
227 | ||
228 | ---- | |
229 | ... | |
230 | /git-prune-packed | |
231 | /git-psuh | |
232 | /git-pull | |
233 | /git-push | |
234 | /git-quiltimport | |
235 | /git-range-diff | |
236 | ... | |
237 | ---- | |
238 | ||
239 | Checking `git status` again should show that `git-psuh` has been removed from | |
240 | the untracked list and `.gitignore` has been added to the modified list. Now we | |
241 | can stage and commit: | |
242 | ||
76644e32 | 243 | ---- |
2656fb16 | 244 | $ git add Makefile builtin.h builtin/psuh.c git.c .gitignore |
76644e32 ES |
245 | $ git commit -s |
246 | ---- | |
247 | ||
248 | You will be presented with your editor in order to write a commit message. Start | |
249 | the commit with a 50-column or less subject line, including the name of the | |
250 | component you're working on, followed by a blank line (always required) and then | |
251 | the body of your commit message, which should provide the bulk of the context. | |
252 | Remember to be explicit and provide the "Why" of your change, especially if it | |
253 | couldn't easily be understood from your diff. When editing your commit message, | |
3abd4a67 | 254 | don't remove the `Signed-off-by` trailer which was added by `-s` above. |
76644e32 ES |
255 | |
256 | ---- | |
257 | psuh: add a built-in by popular demand | |
258 | ||
259 | Internal metrics indicate this is a command many users expect to be | |
260 | present. So here's an implementation to help drive customer | |
261 | satisfaction and engagement: a pony which doubtfully greets the user, | |
262 | or, a Pony Saying "Um, Hello" (PSUH). | |
263 | ||
264 | This commit message is intentionally formatted to 72 columns per line, | |
265 | starts with a single line as "commit message subject" that is written as | |
266 | if to command the codebase to do something (add this, teach a command | |
267 | that). The body of the message is designed to add information about the | |
268 | commit that is not readily deduced from reading the associated diff, | |
269 | such as answering the question "why?". | |
270 | ||
271 | Signed-off-by: A U Thor <author@example.com> | |
272 | ---- | |
273 | ||
274 | Go ahead and inspect your new commit with `git show`. "psuh:" indicates you | |
275 | have modified mainly the `psuh` command. The subject line gives readers an idea | |
276 | of what you've changed. The sign-off line (`-s`) indicates that you agree to | |
277 | the Developer's Certificate of Origin 1.1 (see the | |
278 | `Documentation/SubmittingPatches` +++[[dco]]+++ header). | |
279 | ||
280 | For the remainder of the tutorial, the subject line only will be listed for the | |
281 | sake of brevity. However, fully-fleshed example commit messages are available | |
282 | on the reference implementation linked at the top of this document. | |
283 | ||
5ef811ac | 284 | [[implementation]] |
76644e32 ES |
285 | === Implementation |
286 | ||
287 | It's probably useful to do at least something besides printing out a string. | |
288 | Let's start by having a look at everything we get. | |
289 | ||
2656fb16 ES |
290 | Modify your `cmd_psuh` implementation to dump the args you're passed, keeping |
291 | existing `printf()` calls in place: | |
76644e32 ES |
292 | |
293 | ---- | |
294 | int i; | |
295 | ||
296 | ... | |
297 | ||
298 | printf(Q_("Your args (there is %d):\n", | |
299 | "Your args (there are %d):\n", | |
300 | argc), | |
301 | argc); | |
302 | for (i = 0; i < argc; i++) | |
303 | printf("%d: %s\n", i, argv[i]); | |
304 | ||
305 | printf(_("Your current working directory:\n<top-level>%s%s\n"), | |
306 | prefix ? "/" : "", prefix ? prefix : ""); | |
307 | ||
308 | ---- | |
309 | ||
310 | Build and try it. As you may expect, there's pretty much just whatever we give | |
311 | on the command line, including the name of our command. (If `prefix` is empty | |
312 | for you, try `cd Documentation/ && ../bin-wrappers/git psuh`). That's not so | |
313 | helpful. So what other context can we get? | |
314 | ||
315 | Add a line to `#include "config.h"`. Then, add the following bits to the | |
316 | function body: | |
317 | ||
318 | ---- | |
319 | const char *cfg_name; | |
320 | ||
321 | ... | |
322 | ||
2656fb16 | 323 | git_config(git_default_config, NULL); |
9a53219f | 324 | if (git_config_get_string_tmp("user.name", &cfg_name) > 0) |
76644e32 ES |
325 | printf(_("No name is found in config\n")); |
326 | else | |
327 | printf(_("Your name: %s\n"), cfg_name); | |
328 | ---- | |
329 | ||
330 | `git_config()` will grab the configuration from config files known to Git and | |
9a53219f | 331 | apply standard precedence rules. `git_config_get_string_tmp()` will look up |
76644e32 ES |
332 | a specific key ("user.name") and give you the value. There are a number of |
333 | single-key lookup functions like this one; you can see them all (and more info | |
334 | about how to use `git_config()`) in `Documentation/technical/api-config.txt`. | |
335 | ||
336 | You should see that the name printed matches the one you see when you run: | |
337 | ||
338 | ---- | |
339 | $ git config --get user.name | |
340 | ---- | |
341 | ||
342 | Great! Now we know how to check for values in the Git config. Let's commit this | |
343 | too, so we don't lose our progress. | |
344 | ||
345 | ---- | |
346 | $ git add builtin/psuh.c | |
347 | $ git commit -sm "psuh: show parameters & config opts" | |
348 | ---- | |
349 | ||
350 | NOTE: Again, the above is for sake of brevity in this tutorial. In a real change | |
351 | you should not use `-m` but instead use the editor to write a meaningful | |
352 | message. | |
353 | ||
354 | Still, it'd be nice to know what the user's working context is like. Let's see | |
355 | if we can print the name of the user's current branch. We can mimic the | |
356 | `git status` implementation; the printer is located in `wt-status.c` and we can | |
357 | see that the branch is held in a `struct wt_status`. | |
358 | ||
359 | `wt_status_print()` gets invoked by `cmd_status()` in `builtin/commit.c`. | |
360 | Looking at that implementation we see the status config being populated like so: | |
361 | ||
362 | ---- | |
363 | status_init_config(&s, git_status_config); | |
364 | ---- | |
365 | ||
366 | But as we drill down, we can find that `status_init_config()` wraps a call | |
367 | to `git_config()`. Let's modify the code we wrote in the previous commit. | |
368 | ||
369 | Be sure to include the header to allow you to use `struct wt_status`: | |
370 | ---- | |
371 | #include "wt-status.h" | |
372 | ---- | |
373 | ||
374 | Then modify your `cmd_psuh` implementation to declare your `struct wt_status`, | |
375 | prepare it, and print its contents: | |
376 | ||
377 | ---- | |
378 | struct wt_status status; | |
379 | ||
380 | ... | |
381 | ||
382 | wt_status_prepare(the_repository, &status); | |
383 | git_config(git_default_config, &status); | |
384 | ||
385 | ... | |
386 | ||
387 | printf(_("Your current branch: %s\n"), status.branch); | |
388 | ---- | |
389 | ||
390 | Run it again. Check it out - here's the (verbose) name of your current branch! | |
391 | ||
392 | Let's commit this as well. | |
393 | ||
394 | ---- | |
2656fb16 | 395 | $ git add builtin/psuh.c |
76644e32 ES |
396 | $ git commit -sm "psuh: print the current branch" |
397 | ---- | |
398 | ||
399 | Now let's see if we can get some info about a specific commit. | |
400 | ||
401 | Luckily, there are some helpers for us here. `commit.h` has a function called | |
402 | `lookup_commit_reference_by_name` to which we can simply provide a hardcoded | |
403 | string; `pretty.h` has an extremely handy `pp_commit_easy()` call which doesn't | |
404 | require a full format object to be passed. | |
405 | ||
406 | Add the following includes: | |
407 | ||
408 | ---- | |
409 | #include "commit.h" | |
410 | #include "pretty.h" | |
411 | ---- | |
412 | ||
413 | Then, add the following lines within your implementation of `cmd_psuh()` near | |
414 | the declarations and the logic, respectively. | |
415 | ||
416 | ---- | |
417 | struct commit *c = NULL; | |
418 | struct strbuf commitline = STRBUF_INIT; | |
419 | ||
420 | ... | |
421 | ||
422 | c = lookup_commit_reference_by_name("origin/master"); | |
423 | ||
424 | if (c != NULL) { | |
425 | pp_commit_easy(CMIT_FMT_ONELINE, c, &commitline); | |
426 | printf(_("Current commit: %s\n"), commitline.buf); | |
427 | } | |
428 | ---- | |
429 | ||
430 | The `struct strbuf` provides some safety belts to your basic `char*`, one of | |
431 | which is a length member to prevent buffer overruns. It needs to be initialized | |
432 | nicely with `STRBUF_INIT`. Keep it in mind when you need to pass around `char*`. | |
433 | ||
434 | `lookup_commit_reference_by_name` resolves the name you pass it, so you can play | |
435 | with the value there and see what kind of things you can come up with. | |
436 | ||
437 | `pp_commit_easy` is a convenience wrapper in `pretty.h` that takes a single | |
438 | format enum shorthand, rather than an entire format struct. It then | |
439 | pretty-prints the commit according to that shorthand. These are similar to the | |
440 | formats available with `--pretty=FOO` in many Git commands. | |
441 | ||
442 | Build it and run, and if you're using the same name in the example, you should | |
443 | see the subject line of the most recent commit in `origin/master` that you know | |
444 | about. Neat! Let's commit that as well. | |
445 | ||
446 | ---- | |
2656fb16 | 447 | $ git add builtin/psuh.c |
76644e32 ES |
448 | $ git commit -sm "psuh: display the top of origin/master" |
449 | ---- | |
450 | ||
5ef811ac | 451 | [[add-documentation]] |
76644e32 ES |
452 | === Adding Documentation |
453 | ||
454 | Awesome! You've got a fantastic new command that you're ready to share with the | |
455 | community. But hang on just a minute - this isn't very user-friendly. Run the | |
456 | following: | |
457 | ||
458 | ---- | |
459 | $ ./bin-wrappers/git help psuh | |
460 | ---- | |
461 | ||
462 | Your new command is undocumented! Let's fix that. | |
463 | ||
464 | Take a look at `Documentation/git-*.txt`. These are the manpages for the | |
465 | subcommands that Git knows about. You can open these up and take a look to get | |
466 | acquainted with the format, but then go ahead and make a new file | |
467 | `Documentation/git-psuh.txt`. Like with most of the documentation in the Git | |
468 | project, help pages are written with AsciiDoc (see CodingGuidelines, "Writing | |
469 | Documentation" section). Use the following template to fill out your own | |
470 | manpage: | |
471 | ||
472 | // Surprisingly difficult to embed AsciiDoc source within AsciiDoc. | |
473 | [listing] | |
474 | .... | |
475 | git-psuh(1) | |
476 | =========== | |
477 | ||
478 | NAME | |
479 | ---- | |
480 | git-psuh - Delight users' typo with a shy horse | |
481 | ||
482 | ||
483 | SYNOPSIS | |
484 | -------- | |
485 | [verse] | |
b37e0ec3 | 486 | 'git-psuh [<arg>...]' |
76644e32 ES |
487 | |
488 | DESCRIPTION | |
489 | ----------- | |
490 | ... | |
491 | ||
492 | OPTIONS[[OPTIONS]] | |
493 | ------------------ | |
494 | ... | |
495 | ||
496 | OUTPUT | |
497 | ------ | |
498 | ... | |
499 | ||
76644e32 ES |
500 | GIT |
501 | --- | |
502 | Part of the linkgit:git[1] suite | |
503 | .... | |
504 | ||
505 | The most important pieces of this to note are the file header, underlined by =, | |
506 | the NAME section, and the SYNOPSIS, which would normally contain the grammar if | |
507 | your command took arguments. Try to use well-established manpage headers so your | |
508 | documentation is consistent with other Git and UNIX manpages; this makes life | |
509 | easier for your user, who can skip to the section they know contains the | |
510 | information they need. | |
511 | ||
f5bcde6c ES |
512 | NOTE: Before trying to build the docs, make sure you have the package `asciidoc` |
513 | installed. | |
514 | ||
76644e32 ES |
515 | Now that you've written your manpage, you'll need to build it explicitly. We |
516 | convert your AsciiDoc to troff which is man-readable like so: | |
517 | ||
518 | ---- | |
519 | $ make all doc | |
520 | $ man Documentation/git-psuh.1 | |
521 | ---- | |
522 | ||
523 | or | |
524 | ||
525 | ---- | |
526 | $ make -C Documentation/ git-psuh.1 | |
527 | $ man Documentation/git-psuh.1 | |
528 | ---- | |
529 | ||
76644e32 ES |
530 | While this isn't as satisfying as running through `git help`, you can at least |
531 | check that your help page looks right. | |
532 | ||
533 | You can also check that the documentation coverage is good (that is, the project | |
534 | sees that your command has been implemented as well as documented) by running | |
535 | `make check-docs` from the top-level. | |
536 | ||
537 | Go ahead and commit your new documentation change. | |
538 | ||
5ef811ac | 539 | [[add-usage]] |
76644e32 ES |
540 | === Adding Usage Text |
541 | ||
542 | Try and run `./bin-wrappers/git psuh -h`. Your command should crash at the end. | |
543 | That's because `-h` is a special case which your command should handle by | |
544 | printing usage. | |
545 | ||
546 | Take a look at `Documentation/technical/api-parse-options.txt`. This is a handy | |
547 | tool for pulling out options you need to be able to handle, and it takes a | |
548 | usage string. | |
549 | ||
b37e0ec3 CC |
550 | In order to use it, we'll need to prepare a NULL-terminated array of usage |
551 | strings and a `builtin_psuh_options` array. | |
76644e32 | 552 | |
b37e0ec3 CC |
553 | Add a line to `#include "parse-options.h"`. |
554 | ||
555 | At global scope, add your array of usage strings: | |
76644e32 ES |
556 | |
557 | ---- | |
558 | static const char * const psuh_usage[] = { | |
b37e0ec3 | 559 | N_("git psuh [<arg>...]"), |
76644e32 ES |
560 | NULL, |
561 | }; | |
562 | ---- | |
563 | ||
564 | Then, within your `cmd_psuh()` implementation, we can declare and populate our | |
565 | `option` struct. Ours is pretty boring but you can add more to it if you want to | |
566 | explore `parse_options()` in more detail: | |
567 | ||
568 | ---- | |
569 | struct option options[] = { | |
570 | OPT_END() | |
571 | }; | |
572 | ---- | |
573 | ||
574 | Finally, before you print your args and prefix, add the call to | |
575 | `parse-options()`: | |
576 | ||
577 | ---- | |
578 | argc = parse_options(argc, argv, prefix, options, psuh_usage, 0); | |
579 | ---- | |
580 | ||
581 | This call will modify your `argv` parameter. It will strip the options you | |
582 | specified in `options` from `argv` and the locations pointed to from `options` | |
583 | entries will be updated. Be sure to replace your `argc` with the result from | |
584 | `parse_options()`, or you will be confused if you try to parse `argv` later. | |
585 | ||
586 | It's worth noting the special argument `--`. As you may be aware, many Unix | |
587 | commands use `--` to indicate "end of named parameters" - all parameters after | |
588 | the `--` are interpreted merely as positional arguments. (This can be handy if | |
589 | you want to pass as a parameter something which would usually be interpreted as | |
590 | a flag.) `parse_options()` will terminate parsing when it reaches `--` and give | |
591 | you the rest of the options afterwards, untouched. | |
592 | ||
4ed55629 ES |
593 | Now that you have a usage hint, you can teach Git how to show it in the general |
594 | command list shown by `git help git` or `git help -a`, which is generated from | |
595 | `command-list.txt`. Find the line for 'git-pull' so you can add your 'git-psuh' | |
596 | line above it in alphabetical order. Now, we can add some attributes about the | |
597 | command which impacts where it shows up in the aforementioned help commands. The | |
598 | top of `command-list.txt` shares some information about what each attribute | |
599 | means; in those help pages, the commands are sorted according to these | |
600 | attributes. `git psuh` is user-facing, or porcelain - so we will mark it as | |
601 | "mainporcelain". For "mainporcelain" commands, the comments at the top of | |
602 | `command-list.txt` indicate we can also optionally add an attribute from another | |
603 | list; since `git psuh` shows some information about the user's workspace but | |
604 | doesn't modify anything, let's mark it as "info". Make sure to keep your | |
605 | attributes in the same style as the rest of `command-list.txt` using spaces to | |
606 | align and delineate them: | |
607 | ||
608 | ---- | |
609 | git-prune-packed plumbingmanipulators | |
610 | git-psuh mainporcelain info | |
611 | git-pull mainporcelain remote | |
612 | git-push mainporcelain remote | |
613 | ---- | |
614 | ||
76644e32 ES |
615 | Build again. Now, when you run with `-h`, you should see your usage printed and |
616 | your command terminated before anything else interesting happens. Great! | |
617 | ||
618 | Go ahead and commit this one, too. | |
619 | ||
5ef811ac | 620 | [[testing]] |
76644e32 ES |
621 | == Testing |
622 | ||
623 | It's important to test your code - even for a little toy command like this one. | |
624 | Moreover, your patch won't be accepted into the Git tree without tests. Your | |
625 | tests should: | |
626 | ||
627 | * Illustrate the current behavior of the feature | |
628 | * Prove the current behavior matches the expected behavior | |
629 | * Ensure the externally-visible behavior isn't broken in later changes | |
630 | ||
631 | So let's write some tests. | |
632 | ||
633 | Related reading: `t/README` | |
634 | ||
5ef811ac | 635 | [[overview-test-structure]] |
76644e32 ES |
636 | === Overview of Testing Structure |
637 | ||
638 | The tests in Git live in `t/` and are named with a 4-digit decimal number using | |
639 | the schema shown in the Naming Tests section of `t/README`. | |
640 | ||
5ef811ac | 641 | [[write-new-test]] |
76644e32 ES |
642 | === Writing Your Test |
643 | ||
644 | Since this a toy command, let's go ahead and name the test with t9999. However, | |
645 | as many of the family/subcmd combinations are full, best practice seems to be | |
646 | to find a command close enough to the one you've added and share its naming | |
647 | space. | |
648 | ||
649 | Create a new file `t/t9999-psuh-tutorial.sh`. Begin with the header as so (see | |
650 | "Writing Tests" and "Source 'test-lib.sh'" in `t/README`): | |
651 | ||
652 | ---- | |
653 | #!/bin/sh | |
654 | ||
655 | test_description='git-psuh test | |
656 | ||
657 | This test runs git-psuh and makes sure it does not crash.' | |
658 | ||
659 | . ./test-lib.sh | |
660 | ---- | |
661 | ||
662 | Tests are framed inside of a `test_expect_success` in order to output TAP | |
663 | formatted results. Let's make sure that `git psuh` doesn't exit poorly and does | |
664 | mention the right animal somewhere: | |
665 | ||
666 | ---- | |
667 | test_expect_success 'runs correctly with no args and good output' ' | |
668 | git psuh >actual && | |
d162b25f | 669 | grep Pony actual |
76644e32 ES |
670 | ' |
671 | ---- | |
672 | ||
673 | Indicate that you've run everything you wanted by adding the following at the | |
674 | bottom of your script: | |
675 | ||
676 | ---- | |
677 | test_done | |
678 | ---- | |
679 | ||
680 | Make sure you mark your test script executable: | |
681 | ||
682 | ---- | |
683 | $ chmod +x t/t9999-psuh-tutorial.sh | |
684 | ---- | |
685 | ||
686 | You can get an idea of whether you created your new test script successfully | |
687 | by running `make -C t test-lint`, which will check for things like test number | |
688 | uniqueness, executable bit, and so on. | |
689 | ||
5ef811ac | 690 | [[local-test]] |
76644e32 ES |
691 | === Running Locally |
692 | ||
693 | Let's try and run locally: | |
694 | ||
695 | ---- | |
696 | $ make | |
697 | $ cd t/ && prove t9999-psuh-tutorial.sh | |
698 | ---- | |
699 | ||
700 | You can run the full test suite and ensure `git-psuh` didn't break anything: | |
701 | ||
702 | ---- | |
703 | $ cd t/ | |
704 | $ prove -j$(nproc) --shuffle t[0-9]*.sh | |
705 | ---- | |
706 | ||
707 | NOTE: You can also do this with `make test` or use any testing harness which can | |
708 | speak TAP. `prove` can run concurrently. `shuffle` randomizes the order the | |
709 | tests are run in, which makes them resilient against unwanted inter-test | |
710 | dependencies. `prove` also makes the output nicer. | |
711 | ||
712 | Go ahead and commit this change, as well. | |
713 | ||
5ef811ac | 714 | [[ready-to-share]] |
489ef3ba | 715 | == Getting Ready to Share: Anatomy of a Patch Series |
76644e32 ES |
716 | |
717 | You may have noticed already that the Git project performs its code reviews via | |
718 | emailed patches, which are then applied by the maintainer when they are ready | |
489ef3ba | 719 | and approved by the community. The Git project does not accept contributions from |
76644e32 | 720 | pull requests, and the patches emailed for review need to be formatted a |
489ef3ba PB |
721 | specific way. |
722 | ||
723 | :patch-series: https://lore.kernel.org/git/pull.1218.git.git.1645209647.gitgitgadget@gmail.com/ | |
724 | :lore: https://lore.kernel.org/git/ | |
725 | ||
726 | Before taking a look at how to convert your commits into emailed patches, | |
727 | let's analyze what the end result, a "patch series", looks like. Here is an | |
728 | {patch-series}[example] of the summary view for a patch series on the web interface of | |
729 | the {lore}[Git mailing list archive]: | |
730 | ||
731 | ---- | |
732 | 2022-02-18 18:40 [PATCH 0/3] libify reflog John Cai via GitGitGadget | |
733 | 2022-02-18 18:40 ` [PATCH 1/3] reflog: libify delete reflog function and helpers John Cai via GitGitGadget | |
734 | 2022-02-18 19:10 ` Ævar Arnfjörð Bjarmason [this message] | |
735 | 2022-02-18 19:39 ` Taylor Blau | |
736 | 2022-02-18 19:48 ` Ævar Arnfjörð Bjarmason | |
737 | 2022-02-18 19:35 ` Taylor Blau | |
738 | 2022-02-21 1:43 ` John Cai | |
739 | 2022-02-21 1:50 ` Taylor Blau | |
740 | 2022-02-23 19:50 ` John Cai | |
c5353c45 | 741 | 2022-02-18 20:00 ` // other replies elided |
489ef3ba PB |
742 | 2022-02-18 18:40 ` [PATCH 2/3] reflog: call reflog_delete from reflog.c John Cai via GitGitGadget |
743 | 2022-02-18 19:15 ` Ævar Arnfjörð Bjarmason | |
744 | 2022-02-18 20:26 ` Junio C Hamano | |
745 | 2022-02-18 18:40 ` [PATCH 3/3] stash: call reflog_delete from reflog.c John Cai via GitGitGadget | |
746 | 2022-02-18 19:20 ` Ævar Arnfjörð Bjarmason | |
747 | 2022-02-19 0:21 ` Taylor Blau | |
748 | 2022-02-22 2:36 ` John Cai | |
749 | 2022-02-22 10:51 ` Ævar Arnfjörð Bjarmason | |
750 | 2022-02-18 19:29 ` [PATCH 0/3] libify reflog Ævar Arnfjörð Bjarmason | |
751 | 2022-02-22 18:30 ` [PATCH v2 0/3] libify reflog John Cai via GitGitGadget | |
752 | 2022-02-22 18:30 ` [PATCH v2 1/3] stash: add test to ensure reflog --rewrite --updatref behavior John Cai via GitGitGadget | |
753 | 2022-02-23 8:54 ` Ævar Arnfjörð Bjarmason | |
754 | 2022-02-23 21:27 ` Junio C Hamano | |
755 | // continued | |
756 | ---- | |
757 | ||
758 | We can note a few things: | |
759 | ||
760 | - Each commit is sent as a separate email, with the commit message title as | |
761 | subject, prefixed with "[PATCH _i_/_n_]" for the _i_-th commit of an | |
762 | _n_-commit series. | |
763 | - Each patch is sent as a reply to an introductory email called the _cover | |
764 | letter_ of the series, prefixed "[PATCH 0/_n_]". | |
afc8c925 PB |
765 | - Subsequent iterations of the patch series are labelled "PATCH v2", "PATCH |
766 | v3", etc. in place of "PATCH". For example, "[PATCH v2 1/3]" would be the first of | |
767 | three patches in the second iteration. Each iteration is sent with a new cover | |
768 | letter (like "[PATCH v2 0/3]" above), itself a reply to the cover letter of the | |
769 | previous iteration (more on that below). | |
770 | ||
771 | NOTE: A single-patch topic is sent with "[PATCH]", "[PATCH v2]", etc. without | |
772 | _i_/_n_ numbering (in the above thread overview, no single-patch topic appears, | |
773 | though). | |
774 | ||
775 | [[cover-letter]] | |
776 | === The cover letter | |
777 | ||
778 | In addition to an email per patch, the Git community also expects your patches | |
779 | to come with a cover letter. This is an important component of change | |
780 | submission as it explains to the community from a high level what you're trying | |
781 | to do, and why, in a way that's more apparent than just looking at your | |
782 | patches. | |
783 | ||
784 | The title of your cover letter should be something which succinctly covers the | |
785 | purpose of your entire topic branch. It's often in the imperative mood, just | |
786 | like our commit message titles. Here is how we'll title our series: | |
787 | ||
788 | --- | |
789 | Add the 'psuh' command | |
790 | --- | |
791 | ||
792 | The body of the cover letter is used to give additional context to reviewers. | |
793 | Be sure to explain anything your patches don't make clear on their own, but | |
794 | remember that since the cover letter is not recorded in the commit history, | |
795 | anything that might be useful to future readers of the repository's history | |
796 | should also be in your commit messages. | |
797 | ||
798 | Here's an example body for `psuh`: | |
799 | ||
800 | ---- | |
801 | Our internal metrics indicate widespread interest in the command | |
802 | git-psuh - that is, many users are trying to use it, but finding it is | |
803 | unavailable, using some unknown workaround instead. | |
804 | ||
805 | The following handful of patches add the psuh command and implement some | |
806 | handy features on top of it. | |
807 | ||
808 | This patchset is part of the MyFirstContribution tutorial and should not | |
809 | be merged. | |
810 | ---- | |
489ef3ba PB |
811 | |
812 | At this point the tutorial diverges, in order to demonstrate two | |
76644e32 ES |
813 | different methods of formatting your patchset and getting it reviewed. |
814 | ||
815 | The first method to be covered is GitGitGadget, which is useful for those | |
816 | already familiar with GitHub's common pull request workflow. This method | |
817 | requires a GitHub account. | |
818 | ||
819 | The second method to be covered is `git send-email`, which can give slightly | |
820 | more fine-grained control over the emails to be sent. This method requires some | |
821 | setup which can change depending on your system and will not be covered in this | |
822 | tutorial. | |
823 | ||
824 | Regardless of which method you choose, your engagement with reviewers will be | |
825 | the same; the review process will be covered after the sections on GitGitGadget | |
826 | and `git send-email`. | |
827 | ||
5ef811ac | 828 | [[howto-ggg]] |
76644e32 ES |
829 | == Sending Patches via GitGitGadget |
830 | ||
831 | One option for sending patches is to follow a typical pull request workflow and | |
832 | send your patches out via GitGitGadget. GitGitGadget is a tool created by | |
833 | Johannes Schindelin to make life as a Git contributor easier for those used to | |
834 | the GitHub PR workflow. It allows contributors to open pull requests against its | |
835 | mirror of the Git project, and does some magic to turn the PR into a set of | |
836 | emails and send them out for you. It also runs the Git continuous integration | |
d05b08cd | 837 | suite for you. It's documented at https://gitgitgadget.github.io/. |
76644e32 | 838 | |
5ef811ac | 839 | [[create-fork]] |
76644e32 ES |
840 | === Forking `git/git` on GitHub |
841 | ||
842 | Before you can send your patch off to be reviewed using GitGitGadget, you will | |
843 | need to fork the Git project and upload your changes. First thing - make sure | |
844 | you have a GitHub account. | |
845 | ||
846 | Head to the https://github.com/git/git[GitHub mirror] and look for the Fork | |
847 | button. Place your fork wherever you deem appropriate and create it. | |
848 | ||
5ef811ac | 849 | [[upload-to-fork]] |
76644e32 ES |
850 | === Uploading to Your Own Fork |
851 | ||
852 | To upload your branch to your own fork, you'll need to add the new fork as a | |
853 | remote. You can use `git remote -v` to show the remotes you have added already. | |
854 | From your new fork's page on GitHub, you can press "Clone or download" to get | |
855 | the URL; then you need to run the following to add, replacing your own URL and | |
856 | remote name for the examples provided: | |
857 | ||
858 | ---- | |
859 | $ git remote add remotename git@github.com:remotename/git.git | |
860 | ---- | |
861 | ||
862 | or to use the HTTPS URL: | |
863 | ||
864 | ---- | |
865 | $ git remote add remotename https://github.com/remotename/git/.git | |
866 | ---- | |
867 | ||
868 | Run `git remote -v` again and you should see the new remote showing up. | |
869 | `git fetch remotename` (with the real name of your remote replaced) in order to | |
870 | get ready to push. | |
871 | ||
872 | Next, double-check that you've been doing all your development in a new branch | |
873 | by running `git branch`. If you didn't, now is a good time to move your new | |
874 | commits to their own branch. | |
875 | ||
876 | As mentioned briefly at the beginning of this document, we are basing our work | |
877 | on `master`, so go ahead and update as shown below, or using your preferred | |
878 | workflow. | |
879 | ||
880 | ---- | |
881 | $ git checkout master | |
882 | $ git pull -r | |
883 | $ git rebase master psuh | |
884 | ---- | |
885 | ||
886 | Finally, you're ready to push your new topic branch! (Due to our branch and | |
887 | command name choices, be careful when you type the command below.) | |
888 | ||
889 | ---- | |
890 | $ git push remotename psuh | |
891 | ---- | |
892 | ||
893 | Now you should be able to go and check out your newly created branch on GitHub. | |
894 | ||
5ef811ac | 895 | [[send-pr-ggg]] |
76644e32 ES |
896 | === Sending a PR to GitGitGadget |
897 | ||
898 | In order to have your code tested and formatted for review, you need to start by | |
899 | opening a Pull Request against `gitgitgadget/git`. Head to | |
900 | https://github.com/gitgitgadget/git and open a PR either with the "New pull | |
901 | request" button or the convenient "Compare & pull request" button that may | |
902 | appear with the name of your newly pushed branch. | |
903 | ||
c2cd4b59 PB |
904 | Review the PR's title and description, as they're used by GitGitGadget |
905 | respectively as the subject and body of the cover letter for your change. Refer | |
906 | to <<cover-letter,"The cover letter">> above for advice on how to title your | |
907 | submission and what content to include in the description. | |
908 | ||
4ec50080 PB |
909 | NOTE: For single-patch contributions, your commit message should already be |
910 | meaningful and explain at a high level the purpose (what is happening and why) | |
911 | of your patch, so you usually do not need any additional context. In that case, | |
912 | remove the PR description that GitHub automatically generates from your commit | |
913 | message (your PR description should be empty). If you do need to supply even | |
914 | more context, you can do so in that space and it will be appended to the email | |
915 | that GitGitGadget will send, between the three-dash line and the diffstat | |
916 | (see <<single-patch,Bonus Chapter: One-Patch Changes>> for how this looks once | |
917 | submitted). | |
918 | ||
c2cd4b59 | 919 | When you're happy, submit your pull request. |
76644e32 | 920 | |
5ef811ac | 921 | [[run-ci-ggg]] |
76644e32 ES |
922 | === Running CI and Getting Ready to Send |
923 | ||
924 | If it's your first time using GitGitGadget (which is likely, as you're using | |
925 | this tutorial) then someone will need to give you permission to use the tool. | |
926 | As mentioned in the GitGitGadget documentation, you just need someone who | |
927 | already uses it to comment on your PR with `/allow <username>`. GitGitGadget | |
928 | will automatically run your PRs through the CI even without the permission given | |
929 | but you will not be able to `/submit` your changes until someone allows you to | |
930 | use the tool. | |
931 | ||
3c8d754c ES |
932 | NOTE: You can typically find someone who can `/allow` you on GitGitGadget by |
933 | either examining recent pull requests where someone has been granted `/allow` | |
934 | (https://github.com/gitgitgadget/git/pulls?utf8=%E2%9C%93&q=is%3Apr+is%3Aopen+%22%2Fallow%22[Search: | |
935 | is:pr is:open "/allow"]), in which case both the author and the person who | |
936 | granted the `/allow` can now `/allow` you, or by inquiring on the | |
91d23470 | 937 | https://web.libera.chat/#git-devel[#git-devel] IRC channel on Libera Chat |
3c8d754c ES |
938 | linking your pull request and asking for someone to `/allow` you. |
939 | ||
76644e32 ES |
940 | If the CI fails, you can update your changes with `git rebase -i` and push your |
941 | branch again: | |
942 | ||
943 | ---- | |
944 | $ git push -f remotename psuh | |
945 | ---- | |
946 | ||
947 | In fact, you should continue to make changes this way up until the point when | |
948 | your patch is accepted into `next`. | |
949 | ||
950 | //// | |
951 | TODO https://github.com/gitgitgadget/gitgitgadget/issues/83 | |
952 | It'd be nice to be able to verify that the patch looks good before sending it | |
953 | to everyone on Git mailing list. | |
5ef811ac | 954 | [[check-work-ggg]] |
76644e32 ES |
955 | === Check Your Work |
956 | //// | |
957 | ||
5ef811ac | 958 | [[send-mail-ggg]] |
76644e32 ES |
959 | === Sending Your Patches |
960 | ||
961 | Now that your CI is passing and someone has granted you permission to use | |
962 | GitGitGadget with the `/allow` command, sending out for review is as simple as | |
963 | commenting on your PR with `/submit`. | |
964 | ||
5ef811ac | 965 | [[responding-ggg]] |
76644e32 ES |
966 | === Updating With Comments |
967 | ||
968 | Skip ahead to <<reviewing,Responding to Reviews>> for information on how to | |
969 | reply to review comments you will receive on the mailing list. | |
970 | ||
971 | Once you have your branch again in the shape you want following all review | |
972 | comments, you can submit again: | |
973 | ||
974 | ---- | |
975 | $ git push -f remotename psuh | |
976 | ---- | |
977 | ||
978 | Next, go look at your pull request against GitGitGadget; you should see the CI | |
979 | has been kicked off again. Now while the CI is running is a good time for you | |
980 | to modify your description at the top of the pull request thread; it will be | |
981 | used again as the cover letter. You should use this space to describe what | |
982 | has changed since your previous version, so that your reviewers have some idea | |
983 | of what they're looking at. When the CI is done running, you can comment once | |
984 | more with `/submit` - GitGitGadget will automatically add a v2 mark to your | |
985 | changes. | |
986 | ||
5ef811ac | 987 | [[howto-git-send-email]] |
76644e32 ES |
988 | == Sending Patches with `git send-email` |
989 | ||
990 | If you don't want to use GitGitGadget, you can also use Git itself to mail your | |
991 | patches. Some benefits of using Git this way include finer grained control of | |
992 | subject line (for example, being able to use the tag [RFC PATCH] in the subject) | |
993 | and being able to send a ``dry run'' mail to yourself to ensure it all looks | |
994 | good before going out to the list. | |
995 | ||
5ef811ac | 996 | [[setup-git-send-email]] |
76644e32 ES |
997 | === Prerequisite: Setting Up `git send-email` |
998 | ||
999 | Configuration for `send-email` can vary based on your operating system and email | |
1000 | provider, and so will not be covered in this tutorial, beyond stating that in | |
1001 | many distributions of Linux, `git-send-email` is not packaged alongside the | |
1002 | typical `git` install. You may need to install this additional package; there | |
1003 | are a number of resources online to help you do so. You will also need to | |
1004 | determine the right way to configure it to use your SMTP server; again, as this | |
1005 | configuration can change significantly based on your system and email setup, it | |
1006 | is out of scope for the context of this tutorial. | |
1007 | ||
5ef811ac | 1008 | [[format-patch]] |
76644e32 ES |
1009 | === Preparing Initial Patchset |
1010 | ||
1011 | Sending emails with Git is a two-part process; before you can prepare the emails | |
1012 | themselves, you'll need to prepare the patches. Luckily, this is pretty simple: | |
1013 | ||
1014 | ---- | |
0b45a41d JH |
1015 | $ git format-patch --cover-letter -o psuh/ --base=auto psuh@{u}..psuh |
1016 | ---- | |
1017 | ||
1018 | . The `--cover-letter` option tells `format-patch` to create a | |
1019 | cover letter template for you. You will need to fill in the | |
1020 | template before you're ready to send - but for now, the template | |
1021 | will be next to your other patches. | |
1022 | ||
1023 | . The `-o psuh/` option tells `format-patch` to place the patch | |
1024 | files into a directory. This is useful because `git send-email` | |
1025 | can take a directory and send out all the patches from there. | |
1026 | ||
1027 | . The `--base=auto` option tells the command to record the "base | |
1028 | commit", on which the recipient is expected to apply the patch | |
1029 | series. The `auto` value will cause `format-patch` to compute | |
1030 | the base commit automatically, which is the merge base of tip | |
1031 | commit of the remote-tracking branch and the specified revision | |
1032 | range. | |
1033 | ||
1034 | . The `psuh@{u}..psuh` option tells `format-patch` to generate | |
1035 | patches for the commits you created on the `psuh` branch since it | |
1036 | forked from its upstream (which is `origin/master` if you | |
1037 | followed the example in the "Set up your workspace" section). If | |
1038 | you are already on the `psuh` branch, you can just say `@{u}`, | |
1039 | which means "commits on the current branch since it forked from | |
1040 | its upstream", which is the same thing. | |
1041 | ||
1042 | The command will make one patch file per commit. After you | |
76644e32 ES |
1043 | run, you can go have a look at each of the patches with your favorite text |
1044 | editor and make sure everything looks alright; however, it's not recommended to | |
1045 | make code fixups via the patch file. It's a better idea to make the change the | |
1046 | normal way using `git rebase -i` or by adding a new commit than by modifying a | |
1047 | patch. | |
1048 | ||
1049 | NOTE: Optionally, you can also use the `--rfc` flag to prefix your patch subject | |
1050 | with ``[RFC PATCH]'' instead of ``[PATCH]''. RFC stands for ``request for | |
1051 | comments'' and indicates that while your code isn't quite ready for submission, | |
1052 | you'd like to begin the code review process. This can also be used when your | |
1053 | patch is a proposal, but you aren't sure whether the community wants to solve | |
1054 | the problem with that approach or not - to conduct a sort of design review. You | |
1055 | may also see on the list patches marked ``WIP'' - this means they are incomplete | |
1056 | but want reviewers to look at what they have so far. You can add this flag with | |
1057 | `--subject-prefix=WIP`. | |
1058 | ||
1059 | Check and make sure that your patches and cover letter template exist in the | |
1060 | directory you specified - you're nearly ready to send out your review! | |
1061 | ||
afc8c925 | 1062 | [[preparing-cover-letter]] |
76644e32 ES |
1063 | === Preparing Email |
1064 | ||
e97d474c PB |
1065 | Since you invoked `format-patch` with `--cover-letter`, you've already got a |
1066 | cover letter template ready. Open it up in your favorite editor. | |
76644e32 ES |
1067 | |
1068 | You should see a number of headers present already. Check that your `From:` | |
e97d474c PB |
1069 | header is correct. Then modify your `Subject:` (see <<cover-letter,above>> for |
1070 | how to choose good title for your patch series): | |
76644e32 ES |
1071 | |
1072 | ---- | |
e97d474c | 1073 | Subject: [PATCH 0/7] Add the 'psuh' command |
76644e32 ES |
1074 | ---- |
1075 | ||
1076 | Make sure you retain the ``[PATCH 0/X]'' part; that's what indicates to the Git | |
e97d474c PB |
1077 | community that this email is the beginning of a patch series, and many |
1078 | reviewers filter their email for this type of flag. | |
76644e32 ES |
1079 | |
1080 | You'll need to add some extra parameters when you invoke `git send-email` to add | |
1081 | the cover letter. | |
1082 | ||
e97d474c PB |
1083 | Next you'll have to fill out the body of your cover letter. Again, see |
1084 | <<cover-letter,above>> for what content to include. | |
76644e32 ES |
1085 | |
1086 | The template created by `git format-patch --cover-letter` includes a diffstat. | |
1087 | This gives reviewers a summary of what they're in for when reviewing your topic. | |
1088 | The one generated for `psuh` from the sample implementation looks like this: | |
1089 | ||
1090 | ---- | |
1091 | Documentation/git-psuh.txt | 40 +++++++++++++++++++++ | |
1092 | Makefile | 1 + | |
1093 | builtin.h | 1 + | |
1094 | builtin/psuh.c | 73 ++++++++++++++++++++++++++++++++++++++ | |
1095 | git.c | 1 + | |
1096 | t/t9999-psuh-tutorial.sh | 12 +++++++ | |
1097 | 6 files changed, 128 insertions(+) | |
1098 | create mode 100644 Documentation/git-psuh.txt | |
1099 | create mode 100644 builtin/psuh.c | |
1100 | create mode 100755 t/t9999-psuh-tutorial.sh | |
1101 | ---- | |
1102 | ||
1103 | Finally, the letter will include the version of Git used to generate the | |
1104 | patches. You can leave that string alone. | |
1105 | ||
5ef811ac | 1106 | [[sending-git-send-email]] |
76644e32 ES |
1107 | === Sending Email |
1108 | ||
1109 | At this point you should have a directory `psuh/` which is filled with your | |
1110 | patches and a cover letter. Time to mail it out! You can send it like this: | |
1111 | ||
1112 | ---- | |
1113 | $ git send-email --to=target@example.com psuh/*.patch | |
1114 | ---- | |
1115 | ||
1116 | NOTE: Check `git help send-email` for some other options which you may find | |
1117 | valuable, such as changing the Reply-to address or adding more CC and BCC lines. | |
1118 | ||
7e50b3f5 LA |
1119 | :contrib-scripts: footnoteref:[contrib-scripts,Scripts under `contrib/` are + |
1120 | not part of the core `git` binary and must be called directly. Clone the Git + | |
1121 | codebase and run `perl contrib/contacts/git-contacts`.] | |
1122 | ||
1123 | NOTE: If you're not sure whom to CC, running `contrib/contacts/git-contacts` can | |
1124 | list potential reviewers. In addition, you can do `git send-email | |
1125 | --cc-cmd='perl contrib/contacts/git-contacts' feature/*.patch`{contrib-scripts} to | |
1126 | automatically pass this list of emails to `send-email`. | |
1127 | ||
76644e32 ES |
1128 | NOTE: When you are sending a real patch, it will go to git@vger.kernel.org - but |
1129 | please don't send your patchset from the tutorial to the real mailing list! For | |
1130 | now, you can send it to yourself, to make sure you understand how it will look. | |
1131 | ||
1132 | After you run the command above, you will be presented with an interactive | |
1133 | prompt for each patch that's about to go out. This gives you one last chance to | |
1134 | edit or quit sending something (but again, don't edit code this way). Once you | |
1135 | press `y` or `a` at these prompts your emails will be sent! Congratulations! | |
1136 | ||
1137 | Awesome, now the community will drop everything and review your changes. (Just | |
1138 | kidding - be patient!) | |
1139 | ||
5ef811ac | 1140 | [[v2-git-send-email]] |
76644e32 ES |
1141 | === Sending v2 |
1142 | ||
1cc31e15 GC |
1143 | This section will focus on how to send a v2 of your patchset. To learn what |
1144 | should go into v2, skip ahead to <<reviewing,Responding to Reviews>> for | |
1145 | information on how to handle comments from reviewers. | |
1146 | ||
1147 | We'll reuse our `psuh` topic branch for v2. Before we make any changes, we'll | |
1148 | mark the tip of our v1 branch for easy reference: | |
76644e32 | 1149 | |
1cc31e15 GC |
1150 | ---- |
1151 | $ git checkout psuh | |
1152 | $ git branch psuh-v1 | |
1153 | ---- | |
76644e32 | 1154 | |
1cc31e15 GC |
1155 | Refine your patch series by using `git rebase -i` to adjust commits based upon |
1156 | reviewer comments. Once the patch series is ready for submission, generate your | |
1157 | patches again, but with some new flags: | |
76644e32 ES |
1158 | |
1159 | ---- | |
1cc31e15 | 1160 | $ git format-patch -v2 --cover-letter -o psuh/ --range-diff master..psuh-v1 master.. |
76644e32 ES |
1161 | ---- |
1162 | ||
1cc31e15 GC |
1163 | The `--range-diff master..psuh-v1` parameter tells `format-patch` to include a |
1164 | range-diff between `psuh-v1` and `psuh` in the cover letter (see | |
1165 | linkgit:git-range-diff[1]). This helps tell reviewers about the differences | |
1166 | between your v1 and v2 patches. | |
1167 | ||
1168 | The `-v2` parameter tells `format-patch` to output your patches | |
1169 | as version "2". For instance, you may notice that your v2 patches are | |
1170 | all named like `v2-000n-my-commit-subject.patch`. `-v2` will also format | |
1171 | your patches by prefixing them with "[PATCH v2]" instead of "[PATCH]", | |
1172 | and your range-diff will be prefaced with "Range-diff against v1". | |
1173 | ||
72991ff5 | 1174 | After you run this command, `format-patch` will output the patches to the `psuh/` |
1cc31e15 GC |
1175 | directory, alongside the v1 patches. Using a single directory makes it easy to |
1176 | refer to the old v1 patches while proofreading the v2 patches, but you will need | |
1177 | to be careful to send out only the v2 patches. We will use a pattern like | |
78b6369e | 1178 | `psuh/v2-*.patch` (not `psuh/*.patch`, which would match v1 and v2 patches). |
76644e32 ES |
1179 | |
1180 | Edit your cover letter again. Now is a good time to mention what's different | |
1181 | between your last version and now, if it's something significant. You do not | |
1182 | need the exact same body in your second cover letter; focus on explaining to | |
1183 | reviewers the changes you've made that may not be as visible. | |
1184 | ||
ba4324c4 | 1185 | You will also need to go and find the Message-ID of your previous cover letter. |
76644e32 ES |
1186 | You can either note it when you send the first series, from the output of `git |
1187 | send-email`, or you can look it up on the | |
46c67492 | 1188 | https://lore.kernel.org/git[mailing list]. Find your cover letter in the |
ba4324c4 | 1189 | archives, click on it, then click "permalink" or "raw" to reveal the Message-ID |
76644e32 ES |
1190 | header. It should match: |
1191 | ||
1192 | ---- | |
ba4324c4 | 1193 | Message-ID: <foo.12345.author@example.com> |
76644e32 ES |
1194 | ---- |
1195 | ||
ba4324c4 JH |
1196 | Your Message-ID is `<foo.12345.author@example.com>`. This example will be used |
1197 | below as well; make sure to replace it with the correct Message-ID for your | |
1198 | **previous cover letter** - that is, if you're sending v2, use the Message-ID | |
1199 | from v1; if you're sending v3, use the Message-ID from v2. | |
76644e32 ES |
1200 | |
1201 | While you're looking at the email, you should also note who is CC'd, as it's | |
1202 | common practice in the mailing list to keep all CCs on a thread. You can add | |
1203 | these CC lines directly to your cover letter with a line like so in the header | |
1204 | (before the Subject line): | |
1205 | ||
1206 | ---- | |
1207 | CC: author@example.com, Othe R <other@example.com> | |
1208 | ---- | |
1209 | ||
1210 | Now send the emails again, paying close attention to which messages you pass in | |
1211 | to the command: | |
1212 | ||
1213 | ---- | |
1214 | $ git send-email --to=target@example.com | |
1215 | --in-reply-to="<foo.12345.author@example.com>" | |
1cc31e15 | 1216 | psuh/v2-*.patch |
76644e32 ES |
1217 | ---- |
1218 | ||
5ef811ac | 1219 | [[single-patch]] |
76644e32 ES |
1220 | === Bonus Chapter: One-Patch Changes |
1221 | ||
1222 | In some cases, your very small change may consist of only one patch. When that | |
1223 | happens, you only need to send one email. Your commit message should already be | |
1224 | meaningful and explain at a high level the purpose (what is happening and why) | |
1225 | of your patch, but if you need to supply even more context, you can do so below | |
1226 | the `---` in your patch. Take the example below, which was generated with `git | |
1227 | format-patch` on a single commit, and then edited to add the content between | |
1228 | the `---` and the diffstat. | |
1229 | ||
1230 | ---- | |
1231 | From 1345bbb3f7ac74abde040c12e737204689a72723 Mon Sep 17 00:00:00 2001 | |
1232 | From: A U Thor <author@example.com> | |
1233 | Date: Thu, 18 Apr 2019 15:11:02 -0700 | |
1234 | Subject: [PATCH] README: change the grammar | |
1235 | ||
1236 | I think it looks better this way. This part of the commit message will | |
1237 | end up in the commit-log. | |
1238 | ||
1239 | Signed-off-by: A U Thor <author@example.com> | |
1240 | --- | |
1241 | Let's have a wild discussion about grammar on the mailing list. This | |
1242 | part of my email will never end up in the commit log. Here is where I | |
1243 | can add additional context to the mailing list about my intent, outside | |
1244 | of the context of the commit log. This section was added after `git | |
1245 | format-patch` was run, by editing the patch file in a text editor. | |
1246 | ||
1247 | README.md | 2 +- | |
1248 | 1 file changed, 1 insertion(+), 1 deletion(-) | |
1249 | ||
1250 | diff --git a/README.md b/README.md | |
1251 | index 88f126184c..38da593a60 100644 | |
1252 | --- a/README.md | |
1253 | +++ b/README.md | |
1254 | @@ -3,7 +3,7 @@ | |
1255 | Git - fast, scalable, distributed revision control system | |
1256 | ========================================================= | |
1257 | ||
1258 | -Git is a fast, scalable, distributed revision control system with an | |
1259 | +Git is a fast, scalable, and distributed revision control system with an | |
1260 | unusually rich command set that provides both high-level operations | |
1261 | and full access to internals. | |
1262 | ||
1263 | -- | |
1264 | 2.21.0.392.gf8f6787159e-goog | |
1265 | ---- | |
1266 | ||
5ef811ac | 1267 | [[now-what]] |
76644e32 ES |
1268 | == My Patch Got Emailed - Now What? |
1269 | ||
010447cf JH |
1270 | Please give reviewers enough time to process your initial patch before |
1271 | sending an updated version. That is, resist the temptation to send a new | |
1272 | version immediately, because others may have already started reviewing | |
1273 | your initial version. | |
1274 | ||
1275 | While waiting for review comments, you may find mistakes in your initial | |
1276 | patch, or perhaps realize a different and better way to achieve the goal | |
1277 | of the patch. In this case you may communicate your findings to other | |
1278 | reviewers as follows: | |
1279 | ||
1280 | - If the mistakes you found are minor, send a reply to your patch as if | |
1281 | you were a reviewer and mention that you will fix them in an | |
1282 | updated version. | |
1283 | ||
1284 | - On the other hand, if you think you want to change the course so | |
1285 | drastically that reviews on the initial patch would be a waste of | |
1286 | time (for everyone involved), retract the patch immediately with | |
1287 | a reply like "I am working on a much better approach, so please | |
1288 | ignore this patch and wait for the updated version." | |
1289 | ||
1290 | Now, the above is a good practice if you sent your initial patch | |
1291 | prematurely without polish. But a better approach of course is to avoid | |
1292 | sending your patch prematurely in the first place. | |
1293 | ||
1294 | Please be considerate of the time needed by reviewers to examine each | |
1295 | new version of your patch. Rather than seeing the initial version right | |
1296 | now (followed by several "oops, I like this version better than the | |
1297 | previous one" patches over 2 days), reviewers would strongly prefer if a | |
1298 | single polished version came 2 days later instead, and that version with | |
1299 | fewer mistakes were the only one they would need to review. | |
1300 | ||
1301 | ||
76644e32 ES |
1302 | [[reviewing]] |
1303 | === Responding to Reviews | |
1304 | ||
1305 | After a few days, you will hopefully receive a reply to your patchset with some | |
1306 | comments. Woohoo! Now you can get back to work. | |
1307 | ||
1308 | It's good manners to reply to each comment, notifying the reviewer that you have | |
a6d8d110 | 1309 | made the change suggested, feel the original is better, or that the comment |
76644e32 ES |
1310 | inspired you to do something a new way which is superior to both the original |
1311 | and the suggested change. This way reviewers don't need to inspect your v2 to | |
1312 | figure out whether you implemented their comment or not. | |
1313 | ||
a6d8d110 JH |
1314 | Reviewers may ask you about what you wrote in the patchset, either in |
1315 | the proposed commit log message or in the changes themselves. You | |
1316 | should answer these questions in your response messages, but often the | |
1317 | reason why reviewers asked these questions to understand what you meant | |
1318 | to write is because your patchset needed clarification to be understood. | |
1319 | ||
1320 | Do not be satisfied by just answering their questions in your response | |
1321 | and hear them say that they now understand what you wanted to say. | |
1322 | Update your patches to clarify the points reviewers had trouble with, | |
1323 | and prepare your v2; the words you used to explain your v1 to answer | |
1324 | reviewers' questions may be useful thing to use. Your goal is to make | |
1325 | your v2 clear enough so that it becomes unnecessary for you to give the | |
1326 | same explanation to the next person who reads it. | |
1327 | ||
76644e32 ES |
1328 | If you are going to push back on a comment, be polite and explain why you feel |
1329 | your original is better; be prepared that the reviewer may still disagree with | |
1330 | you, and the rest of the community may weigh in on one side or the other. As | |
1331 | with all code reviews, it's important to keep an open mind to doing something a | |
1332 | different way than you originally planned; other reviewers have a different | |
1333 | perspective on the project than you do, and may be thinking of a valid side | |
1334 | effect which had not occurred to you. It is always okay to ask for clarification | |
1335 | if you aren't sure why a change was suggested, or what the reviewer is asking | |
1336 | you to do. | |
1337 | ||
1338 | Make sure your email client has a plaintext email mode and it is turned on; the | |
1339 | Git list rejects HTML email. Please also follow the mailing list etiquette | |
1340 | outlined in the | |
1341 | https://kernel.googlesource.com/pub/scm/git/git/+/todo/MaintNotes[Maintainer's | |
1342 | Note], which are similar to etiquette rules in most open source communities | |
1343 | surrounding bottom-posting and inline replies. | |
1344 | ||
1345 | When you're making changes to your code, it is cleanest - that is, the resulting | |
1346 | commits are easiest to look at - if you use `git rebase -i` (interactive | |
1347 | rebase). Take a look at this | |
1348 | https://www.oreilly.com/library/view/git-pocket-guide/9781449327507/ch10.html[overview] | |
1349 | from O'Reilly. The general idea is to modify each commit which requires changes; | |
1350 | this way, instead of having a patch A with a mistake, a patch B which was fine | |
1351 | and required no upstream reviews in v1, and a patch C which fixes patch A for | |
1352 | v2, you can just ship a v2 with a correct patch A and correct patch B. This is | |
1353 | changing history, but since it's local history which you haven't shared with | |
1354 | anyone, that is okay for now! (Later, it may not make sense to do this; take a | |
1355 | look at the section below this one for some context.) | |
1356 | ||
5ef811ac | 1357 | [[after-approval]] |
76644e32 ES |
1358 | === After Review Approval |
1359 | ||
828197de JS |
1360 | The Git project has four integration branches: `seen`, `next`, `master`, and |
1361 | `maint`. Your change will be placed into `seen` fairly early on by the maintainer | |
76644e32 ES |
1362 | while it is still in the review process; from there, when it is ready for wider |
1363 | testing, it will be merged into `next`. Plenty of early testers use `next` and | |
1364 | may report issues. Eventually, changes in `next` will make it to `master`, | |
1365 | which is typically considered stable. Finally, when a new release is cut, | |
1366 | `maint` is used to base bugfixes onto. As mentioned at the beginning of this | |
1367 | document, you can read `Documents/SubmittingPatches` for some more info about | |
1368 | the use of the various integration branches. | |
1369 | ||
1370 | Back to now: your code has been lauded by the upstream reviewers. It is perfect. | |
1371 | It is ready to be accepted. You don't need to do anything else; the maintainer | |
1372 | will merge your topic branch to `next` and life is good. | |
1373 | ||
1374 | However, if you discover it isn't so perfect after this point, you may need to | |
1375 | take some special steps depending on where you are in the process. | |
1376 | ||
1377 | If the maintainer has announced in the "What's cooking in git.git" email that | |
1378 | your topic is marked for `next` - that is, that they plan to merge it to `next` | |
1379 | but have not yet done so - you should send an email asking the maintainer to | |
1380 | wait a little longer: "I've sent v4 of my series and you marked it for `next`, | |
1381 | but I need to change this and that - please wait for v5 before you merge it." | |
1382 | ||
1383 | If the topic has already been merged to `next`, rather than modifying your | |
1384 | patches with `git rebase -i`, you should make further changes incrementally - | |
1385 | that is, with another commit, based on top of the maintainer's topic branch as | |
1386 | detailed in https://github.com/gitster/git. Your work is still in the same topic | |
1387 | but is now incremental, rather than a wholesale rewrite of the topic branch. | |
1388 | ||
1389 | The topic branches in the maintainer's GitHub are mirrored in GitGitGadget, so | |
1390 | if you're sending your reviews out that way, you should be sure to open your PR | |
1391 | against the appropriate GitGitGadget/Git branch. | |
1392 | ||
1393 | If you're using `git send-email`, you can use it the same way as before, but you | |
1394 | should generate your diffs from `<topic>..<mybranch>` and base your work on | |
1395 | `<topic>` instead of `master`. |