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