| 1 | My First Contribution to the Git Project |
| 2 | ======================================== |
| 3 | :sectanchors: |
| 4 | |
| 5 | [[summary]] |
| 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 | |
| 11 | [[prerequisites]] |
| 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 | |
| 17 | [[related-reading]] |
| 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.adoc` |
| 25 | |
| 26 | [[getting-help]] |
| 27 | === Getting Help |
| 28 | |
| 29 | If you get stuck, you can seek help in the following places. |
| 30 | |
| 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 <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 |
| 41 | available to view in a browser. |
| 42 | |
| 43 | ==== https://web.libera.chat/#git-devel[#git-devel] on Libera Chat |
| 44 | |
| 45 | This IRC channel is for conversations between Git contributors. If someone is |
| 46 | currently online and knows the answer to your question, you can receive help |
| 47 | in real time. Otherwise, you can read the |
| 48 | https://colabti.org/irclogger/irclogger_logs/git-devel[scrollback] to see |
| 49 | whether someone answered you. IRC does not allow offline private messaging, so |
| 50 | if you try to private message someone and then log out of IRC, they cannot |
| 51 | respond to you. It's better to ask your questions in the channel so that you |
| 52 | can be answered if you disconnect and so that others can learn from the |
| 53 | conversation. |
| 54 | |
| 55 | ==== https://discord.gg/GRFVkzgxRd[#discord] on Discord |
| 56 | This is an unofficial Git Discord server for everyone, from people just |
| 57 | starting out with Git to those who develop it. It's a great place to ask |
| 58 | questions, share tips, and connect with the broader Git community in real time. |
| 59 | |
| 60 | The server has channels for general discussions and specific channels for those |
| 61 | who use Git and those who develop it. The server's search functionality also |
| 62 | allows you to find previous conversations and answers to common questions. |
| 63 | |
| 64 | [[getting-started]] |
| 65 | == Getting Started |
| 66 | |
| 67 | [[cloning]] |
| 68 | === Clone the Git Repository |
| 69 | |
| 70 | Git is mirrored in a number of locations. Clone the repository from one of them; |
| 71 | https://git-scm.com/downloads suggests one of the best places to clone from is |
| 72 | the mirror on GitHub. |
| 73 | |
| 74 | ---- |
| 75 | $ git clone https://github.com/git/git git |
| 76 | $ cd git |
| 77 | ---- |
| 78 | |
| 79 | [[dependencies]] |
| 80 | === Installing Dependencies |
| 81 | |
| 82 | To build Git from source, you need to have a handful of dependencies installed |
| 83 | on your system. For a hint of what's needed, you can take a look at |
| 84 | `INSTALL`, paying close attention to the section about Git's dependencies on |
| 85 | external programs and libraries. That document mentions a way to "test-drive" |
| 86 | our freshly built Git without installing; that's the method we'll be using in |
| 87 | this tutorial. |
| 88 | |
| 89 | Make sure that your environment has everything you need by building your brand |
| 90 | new clone of Git from the above step: |
| 91 | |
| 92 | ---- |
| 93 | $ make |
| 94 | ---- |
| 95 | |
| 96 | NOTE: The Git build is parallelizable. `-j#` is not included above but you can |
| 97 | use it as you prefer, here and elsewhere. |
| 98 | |
| 99 | [[identify-problem]] |
| 100 | === Identify Problem to Solve |
| 101 | |
| 102 | //// |
| 103 | Use + to indicate fixed-width here; couldn't get ` to work nicely with the |
| 104 | quotes around "Pony Saying 'Um, Hello'". |
| 105 | //// |
| 106 | In this tutorial, we will add a new command, +git psuh+, short for ``Pony Saying |
| 107 | `Um, Hello''' - a feature which has gone unimplemented despite a high frequency |
| 108 | of invocation during users' typical daily workflow. |
| 109 | |
| 110 | (We've seen some other effort in this space with the implementation of popular |
| 111 | commands such as `sl`.) |
| 112 | |
| 113 | [[setup-workspace]] |
| 114 | === Set Up Your Workspace |
| 115 | |
| 116 | Let's start by making a development branch to work on our changes. Per |
| 117 | `Documentation/SubmittingPatches`, since a brand new command is a new feature, |
| 118 | it's fine to base your work on `master`. However, in the future for bugfixes, |
| 119 | etc., you should check that document and base it on the appropriate branch. |
| 120 | |
| 121 | For the purposes of this document, we will base all our work on the `master` |
| 122 | branch of the upstream project. Create the `psuh` branch you will use for |
| 123 | development like so: |
| 124 | |
| 125 | ---- |
| 126 | $ git checkout -b psuh origin/master |
| 127 | ---- |
| 128 | |
| 129 | We'll make a number of commits here in order to demonstrate how to send a topic |
| 130 | with multiple patches up for review simultaneously. |
| 131 | |
| 132 | [[code-it-up]] |
| 133 | == Code It Up! |
| 134 | |
| 135 | NOTE: A reference implementation can be found at |
| 136 | https://github.com/nasamuffin/git/tree/psuh. |
| 137 | |
| 138 | [[add-new-command]] |
| 139 | === Adding a New Command |
| 140 | |
| 141 | Lots of the subcommands are written as builtins, which means they are |
| 142 | implemented in C and compiled into the main `git` executable. Implementing the |
| 143 | very simple `psuh` command as a built-in will demonstrate the structure of the |
| 144 | codebase, the internal API, and the process of working together as a contributor |
| 145 | with the reviewers and maintainer to integrate this change into the system. |
| 146 | |
| 147 | Built-in subcommands are typically implemented in a function named "cmd_" |
| 148 | followed by the name of the subcommand, in a source file named after the |
| 149 | subcommand and contained within `builtin/`. So it makes sense to implement your |
| 150 | command in `builtin/psuh.c`. Create that file, and within it, write the entry |
| 151 | point for your command in a function matching the style and signature: |
| 152 | |
| 153 | ---- |
| 154 | int cmd_psuh(int argc UNUSED, const char **argv UNUSED, |
| 155 | const char *prefix UNUSED, struct repository *repo UNUSED) |
| 156 | ---- |
| 157 | |
| 158 | A few things to note: |
| 159 | |
| 160 | * A subcommand implementation takes its command line arguments |
| 161 | in `int argc` + `const char **argv`, like `main()` would. |
| 162 | |
| 163 | * It also takes two extra parameters, `prefix` and `repo`. What |
| 164 | they mean will not be discussed until much later. |
| 165 | |
| 166 | * Because this first example will not use any of the parameters, |
| 167 | your compiler will give warnings on unused parameters. As the |
| 168 | list of these four parameters is mandated by the API to add |
| 169 | new built-in commands, you cannot omit them. Instead, you add |
| 170 | `UNUSED` to each of them to tell the compiler that you *know* |
| 171 | you are not (yet) using it. |
| 172 | |
| 173 | We'll also need to add the declaration of psuh; open up `builtin.h`, find the |
| 174 | declaration for `cmd_pull`, and add a new line for `psuh` immediately before it, |
| 175 | in order to keep the declarations alphabetically sorted: |
| 176 | |
| 177 | ---- |
| 178 | int cmd_psuh(int argc, const char **argv, const char *prefix, struct repository *repo); |
| 179 | ---- |
| 180 | |
| 181 | Be sure to `#include "builtin.h"` in your `psuh.c`. You'll also need to |
| 182 | `#include "gettext.h"` to use functions related to printing output text. |
| 183 | |
| 184 | Go ahead and add some throwaway printf to the `cmd_psuh` function. This is a |
| 185 | decent starting point as we can now add build rules and register the command. |
| 186 | |
| 187 | NOTE: Your throwaway text, as well as much of the text you will be adding over |
| 188 | the course of this tutorial, is user-facing. That means it needs to be |
| 189 | localizable. Take a look at `po/README` under "Marking strings for translation". |
| 190 | Throughout the tutorial, we will mark strings for translation as necessary; you |
| 191 | should also do so when writing your user-facing commands in the future. |
| 192 | |
| 193 | ---- |
| 194 | int cmd_psuh(int argc UNUSED, const char **argv UNUSED, |
| 195 | const char *prefix UNUSED, struct repository *repo UNUSED) |
| 196 | { |
| 197 | printf(_("Pony saying hello goes here.\n")); |
| 198 | return 0; |
| 199 | } |
| 200 | ---- |
| 201 | |
| 202 | Let's try to build it. Open `Makefile`, find where `builtin/pull.o` is added |
| 203 | to `BUILTIN_OBJS`, and add `builtin/psuh.o` in the same way next to it in |
| 204 | alphabetical order. Once you've done so, move to the top-level directory and |
| 205 | build simply with `make`. Also add the `DEVELOPER=1` variable to turn on |
| 206 | some additional warnings: |
| 207 | |
| 208 | ---- |
| 209 | $ echo DEVELOPER=1 >config.mak |
| 210 | $ make |
| 211 | ---- |
| 212 | |
| 213 | NOTE: When you are developing the Git project, it's preferred that you use the |
| 214 | `DEVELOPER` flag; if there's some reason it doesn't work for you, you can turn |
| 215 | it off, but it's a good idea to mention the problem to the mailing list. |
| 216 | |
| 217 | Great, now your new command builds happily on its own. But nobody invokes it. |
| 218 | Let's change that. |
| 219 | |
| 220 | The list of commands lives in `git.c`. We can register a new command by adding |
| 221 | a `cmd_struct` to the `commands[]` array. `struct cmd_struct` takes a string |
| 222 | with the command name, a function pointer to the command implementation, and a |
| 223 | setup option flag. For now, let's keep mimicking `push`. Find the line where |
| 224 | `cmd_push` is registered, copy it, and modify it for `cmd_psuh`, placing the new |
| 225 | line in alphabetical order (immediately before `cmd_pull`). |
| 226 | |
| 227 | The options are documented in `builtin.h` under "Adding a new built-in." Since |
| 228 | we hope to print some data about the user's current workspace context later, |
| 229 | we need a Git directory, so choose `RUN_SETUP` as your only option. |
| 230 | |
| 231 | Go ahead and build again. You should see a clean build, so let's kick the tires |
| 232 | and see if it works. There's a binary you can use to test with in the |
| 233 | `bin-wrappers` directory. |
| 234 | |
| 235 | ---- |
| 236 | $ ./bin-wrappers/git psuh |
| 237 | ---- |
| 238 | |
| 239 | Check it out! You've got a command! Nice work! Let's commit this. |
| 240 | |
| 241 | `git status` reveals modified `Makefile`, `builtin.h`, and `git.c` as well as |
| 242 | untracked `builtin/psuh.c` and `git-psuh`. First, let's take care of the binary, |
| 243 | which should be ignored. Open `.gitignore` in your editor, find `/git-pull`, and |
| 244 | add an entry for your new command in alphabetical order: |
| 245 | |
| 246 | ---- |
| 247 | ... |
| 248 | /git-prune-packed |
| 249 | /git-psuh |
| 250 | /git-pull |
| 251 | /git-push |
| 252 | /git-quiltimport |
| 253 | /git-range-diff |
| 254 | ... |
| 255 | ---- |
| 256 | |
| 257 | Checking `git status` again should show that `git-psuh` has been removed from |
| 258 | the untracked list and `.gitignore` has been added to the modified list. Now we |
| 259 | can stage and commit: |
| 260 | |
| 261 | ---- |
| 262 | $ git add Makefile builtin.h builtin/psuh.c git.c .gitignore |
| 263 | $ git commit -s |
| 264 | ---- |
| 265 | |
| 266 | You will be presented with your editor in order to write a commit message. Start |
| 267 | the commit with a 50-column or less subject line, including the name of the |
| 268 | component you're working on, followed by a blank line (always required) and then |
| 269 | the body of your commit message, which should provide the bulk of the context. |
| 270 | Remember to be explicit and provide the "Why" of your change, especially if it |
| 271 | couldn't easily be understood from your diff. When editing your commit message, |
| 272 | don't remove the `Signed-off-by` trailer which was added by `-s` above. |
| 273 | |
| 274 | ---- |
| 275 | psuh: add a built-in by popular demand |
| 276 | |
| 277 | Internal metrics indicate this is a command many users expect to be |
| 278 | present. So here's an implementation to help drive customer |
| 279 | satisfaction and engagement: a pony which doubtfully greets the user, |
| 280 | or, a Pony Saying "Um, Hello" (PSUH). |
| 281 | |
| 282 | This commit message is intentionally formatted to 72 columns per line, |
| 283 | starts with a single line as "commit message subject" that is written as |
| 284 | if to command the codebase to do something (add this, teach a command |
| 285 | that). The body of the message is designed to add information about the |
| 286 | commit that is not readily deduced from reading the associated diff, |
| 287 | such as answering the question "why?". |
| 288 | |
| 289 | Signed-off-by: A U Thor <author@example.com> |
| 290 | ---- |
| 291 | |
| 292 | Go ahead and inspect your new commit with `git show`. "psuh:" indicates you |
| 293 | have modified mainly the `psuh` command. The subject line gives readers an idea |
| 294 | of what you've changed. The sign-off line (`-s`) indicates that you agree to |
| 295 | the Developer's Certificate of Origin 1.1 (see the |
| 296 | `Documentation/SubmittingPatches` +++[[dco]]+++ header). |
| 297 | |
| 298 | For the remainder of the tutorial, the subject line only will be listed for the |
| 299 | sake of brevity. However, fully-fleshed example commit messages are available |
| 300 | on the reference implementation linked at the top of this document. |
| 301 | |
| 302 | [[implementation]] |
| 303 | === Implementation |
| 304 | |
| 305 | It's probably useful to do at least something besides printing out a string. |
| 306 | Let's start by having a look at everything we get. |
| 307 | |
| 308 | Modify your `cmd_psuh` implementation to dump the args you're passed, |
| 309 | keeping existing `printf()` calls in place; because the args are now |
| 310 | used, remove the `UNUSED` macro from them: |
| 311 | |
| 312 | ---- |
| 313 | int i; |
| 314 | |
| 315 | ... |
| 316 | |
| 317 | printf(Q_("Your args (there is %d):\n", |
| 318 | "Your args (there are %d):\n", |
| 319 | argc), |
| 320 | argc); |
| 321 | for (i = 0; i < argc; i++) |
| 322 | printf("%d: %s\n", i, argv[i]); |
| 323 | |
| 324 | printf(_("Your current working directory:\n<top-level>%s%s\n"), |
| 325 | prefix ? "/" : "", prefix ? prefix : ""); |
| 326 | |
| 327 | ---- |
| 328 | |
| 329 | Build and try it. As you may expect, there's pretty much just whatever we give |
| 330 | on the command line, including the name of our command. (If `prefix` is empty |
| 331 | for you, try `cd Documentation/ && ../bin-wrappers/git psuh`). That's not so |
| 332 | helpful. So what other context can we get? |
| 333 | |
| 334 | Add a line to `#include "config.h"`, `#include "repository.h"` and |
| 335 | `#include "environment.h"`. |
| 336 | Then, add the following bits to the function body: |
| 337 | function body: |
| 338 | |
| 339 | ---- |
| 340 | const char *cfg_name; |
| 341 | |
| 342 | ... |
| 343 | |
| 344 | repo_config(repo, git_default_config, NULL); |
| 345 | if (repo_config_get_string_tmp(repo, "user.name", &cfg_name)) |
| 346 | printf(_("No name is found in config\n")); |
| 347 | else |
| 348 | printf(_("Your name: %s\n"), cfg_name); |
| 349 | ---- |
| 350 | |
| 351 | `repo_config()` will grab the configuration from config files known to Git and |
| 352 | apply standard precedence rules. `repo_config_get_string_tmp()` will look up |
| 353 | a specific key ("user.name") and give you the value. There are a number of |
| 354 | single-key lookup functions like this one; you can see them all (and more info |
| 355 | about how to use `repo_config()`) in `config.h`. |
| 356 | |
| 357 | You should see that the name printed matches the one you see when you run: |
| 358 | |
| 359 | ---- |
| 360 | $ git config --get user.name |
| 361 | ---- |
| 362 | |
| 363 | Great! Now we know how to check for values in the Git config. Let's commit this |
| 364 | too, so we don't lose our progress. |
| 365 | |
| 366 | ---- |
| 367 | $ git add builtin/psuh.c |
| 368 | $ git commit -sm "psuh: show parameters & config opts" |
| 369 | ---- |
| 370 | |
| 371 | NOTE: Again, the above is for sake of brevity in this tutorial. In a real change |
| 372 | you should not use `-m` but instead use the editor to write a meaningful |
| 373 | message. |
| 374 | |
| 375 | Still, it'd be nice to know what the user's working context is like. Let's see |
| 376 | if we can print the name of the user's current branch. We can mimic the |
| 377 | `git status` implementation; the printer is located in `wt-status.c` and we can |
| 378 | see that the branch is held in a `struct wt_status`. |
| 379 | |
| 380 | `wt_status_print()` gets invoked by `cmd_status()` in `builtin/commit.c`. |
| 381 | Looking at that implementation we see the status config being populated like so: |
| 382 | |
| 383 | ---- |
| 384 | status_init_config(&s, git_status_config); |
| 385 | ---- |
| 386 | |
| 387 | But as we drill down, we can find that `status_init_config()` wraps a call |
| 388 | to `repo_config()`. Let's modify the code we wrote in the previous commit. |
| 389 | |
| 390 | Be sure to include the header to allow you to use `struct wt_status`: |
| 391 | |
| 392 | ---- |
| 393 | #include "wt-status.h" |
| 394 | ---- |
| 395 | |
| 396 | Then modify your `cmd_psuh` implementation to declare your `struct wt_status`, |
| 397 | prepare it, and print its contents: |
| 398 | |
| 399 | ---- |
| 400 | struct wt_status status; |
| 401 | |
| 402 | ... |
| 403 | |
| 404 | wt_status_prepare(repo, &status); |
| 405 | repo_config(repo, git_default_config, &status); |
| 406 | |
| 407 | ... |
| 408 | |
| 409 | printf(_("Your current branch: %s\n"), status.branch); |
| 410 | ---- |
| 411 | |
| 412 | Run it again. Check it out - here's the (verbose) name of your current branch! |
| 413 | |
| 414 | Let's commit this as well. |
| 415 | |
| 416 | ---- |
| 417 | $ git add builtin/psuh.c |
| 418 | $ git commit -sm "psuh: print the current branch" |
| 419 | ---- |
| 420 | |
| 421 | Now let's see if we can get some info about a specific commit. |
| 422 | |
| 423 | Luckily, there are some helpers for us here. `commit.h` has a function called |
| 424 | `lookup_commit_reference_by_name` to which we can simply provide a hardcoded |
| 425 | string; `pretty.h` has an extremely handy `pp_commit_easy()` call which doesn't |
| 426 | require a full format object to be passed. |
| 427 | |
| 428 | Add the following includes: |
| 429 | |
| 430 | ---- |
| 431 | #include "commit.h" |
| 432 | #include "pretty.h" |
| 433 | #include "strbuf.h" |
| 434 | ---- |
| 435 | |
| 436 | Then, add the following lines within your implementation of `cmd_psuh()` near |
| 437 | the declarations and the logic, respectively. |
| 438 | |
| 439 | ---- |
| 440 | struct commit *c = NULL; |
| 441 | struct strbuf commitline = STRBUF_INIT; |
| 442 | |
| 443 | ... |
| 444 | |
| 445 | c = lookup_commit_reference_by_name("origin/master"); |
| 446 | |
| 447 | if (c != NULL) { |
| 448 | pp_commit_easy(CMIT_FMT_ONELINE, c, &commitline); |
| 449 | printf(_("Current commit: %s\n"), commitline.buf); |
| 450 | } |
| 451 | ---- |
| 452 | |
| 453 | The `struct strbuf` provides some safety belts to your basic `char*`, one of |
| 454 | which is a length member to prevent buffer overruns. It needs to be initialized |
| 455 | nicely with `STRBUF_INIT`. Keep it in mind when you need to pass around `char*`. |
| 456 | |
| 457 | `lookup_commit_reference_by_name` resolves the name you pass it, so you can play |
| 458 | with the value there and see what kind of things you can come up with. |
| 459 | |
| 460 | `pp_commit_easy` is a convenience wrapper in `pretty.h` that takes a single |
| 461 | format enum shorthand, rather than an entire format struct. It then |
| 462 | pretty-prints the commit according to that shorthand. These are similar to the |
| 463 | formats available with `--pretty=FOO` in many Git commands. |
| 464 | |
| 465 | Build it and run, and if you're using the same name in the example, you should |
| 466 | see the subject line of the most recent commit in `origin/master` that you know |
| 467 | about. Neat! Let's commit that as well. |
| 468 | |
| 469 | ---- |
| 470 | $ git add builtin/psuh.c |
| 471 | $ git commit -sm "psuh: display the top of origin/master" |
| 472 | ---- |
| 473 | |
| 474 | [[add-documentation]] |
| 475 | === Adding Documentation |
| 476 | |
| 477 | Awesome! You've got a fantastic new command that you're ready to share with the |
| 478 | community. But hang on just a minute - this isn't very user-friendly. Run the |
| 479 | following: |
| 480 | |
| 481 | ---- |
| 482 | $ ./bin-wrappers/git help psuh |
| 483 | ---- |
| 484 | |
| 485 | Your new command is undocumented! Let's fix that. |
| 486 | |
| 487 | Take a look at `Documentation/git-*.adoc`. These are the manpages for the |
| 488 | subcommands that Git knows about. You can open these up and take a look to get |
| 489 | acquainted with the format, but then go ahead and make a new file |
| 490 | `Documentation/git-psuh.adoc`. Like with most of the documentation in the Git |
| 491 | project, help pages are written with AsciiDoc (see CodingGuidelines, "Writing |
| 492 | Documentation" section). Use the following template to fill out your own |
| 493 | manpage: |
| 494 | |
| 495 | // Surprisingly difficult to embed AsciiDoc source within AsciiDoc. |
| 496 | [listing] |
| 497 | .... |
| 498 | git-psuh(1) |
| 499 | =========== |
| 500 | |
| 501 | NAME |
| 502 | ---- |
| 503 | git-psuh - Delight users' typo with a shy horse |
| 504 | |
| 505 | |
| 506 | SYNOPSIS |
| 507 | -------- |
| 508 | [synopsis] |
| 509 | git psuh [<arg>...] |
| 510 | |
| 511 | DESCRIPTION |
| 512 | ----------- |
| 513 | ... |
| 514 | |
| 515 | OPTIONS[[OPTIONS]] |
| 516 | ------------------ |
| 517 | ... |
| 518 | |
| 519 | OUTPUT |
| 520 | ------ |
| 521 | ... |
| 522 | |
| 523 | GIT |
| 524 | --- |
| 525 | Part of the linkgit:git[1] suite |
| 526 | .... |
| 527 | |
| 528 | The most important pieces of this to note are the file header, underlined by =, |
| 529 | the NAME section, and the SYNOPSIS, which would normally contain the grammar if |
| 530 | your command took arguments. Try to use well-established manpage headers so your |
| 531 | documentation is consistent with other Git and UNIX manpages; this makes life |
| 532 | easier for your user, who can skip to the section they know contains the |
| 533 | information they need. |
| 534 | |
| 535 | NOTE: Before trying to build the docs, make sure you have the package `asciidoc` |
| 536 | installed. |
| 537 | |
| 538 | Now that you've written your manpage, you'll need to build it explicitly. We |
| 539 | convert your AsciiDoc to troff which is man-readable like so: |
| 540 | |
| 541 | ---- |
| 542 | $ make all doc |
| 543 | $ man Documentation/git-psuh.1 |
| 544 | ---- |
| 545 | |
| 546 | or |
| 547 | |
| 548 | ---- |
| 549 | $ make -C Documentation/ git-psuh.1 |
| 550 | $ man Documentation/git-psuh.1 |
| 551 | ---- |
| 552 | |
| 553 | While this isn't as satisfying as running through `git help`, you can at least |
| 554 | check that your help page looks right. |
| 555 | |
| 556 | You can also check that the documentation coverage is good (that is, the project |
| 557 | sees that your command has been implemented as well as documented) by running |
| 558 | `make check-docs` from the top-level. |
| 559 | |
| 560 | Go ahead and commit your new documentation change. |
| 561 | |
| 562 | [[add-usage]] |
| 563 | === Adding Usage Text |
| 564 | |
| 565 | Try and run `./bin-wrappers/git psuh -h`. Your command should crash at the end. |
| 566 | That's because `-h` is a special case which your command should handle by |
| 567 | printing usage. |
| 568 | |
| 569 | Take a look at `Documentation/technical/api-parse-options.adoc`. This is a handy |
| 570 | tool for pulling out options you need to be able to handle, and it takes a |
| 571 | usage string. |
| 572 | |
| 573 | In order to use it, we'll need to prepare a NULL-terminated array of usage |
| 574 | strings and a `builtin_psuh_options` array. |
| 575 | |
| 576 | Add a line to `#include "parse-options.h"`. |
| 577 | |
| 578 | At global scope, add your array of usage strings: |
| 579 | |
| 580 | ---- |
| 581 | static const char * const psuh_usage[] = { |
| 582 | N_("git psuh [<arg>...]"), |
| 583 | NULL, |
| 584 | }; |
| 585 | ---- |
| 586 | |
| 587 | Then, within your `cmd_psuh()` implementation, we can declare and populate our |
| 588 | `option` struct. Ours is pretty boring but you can add more to it if you want to |
| 589 | explore `parse_options()` in more detail: |
| 590 | |
| 591 | ---- |
| 592 | struct option options[] = { |
| 593 | OPT_END() |
| 594 | }; |
| 595 | ---- |
| 596 | |
| 597 | Finally, before you print your args and prefix, add the call to |
| 598 | `parse-options()`: |
| 599 | |
| 600 | ---- |
| 601 | argc = parse_options(argc, argv, prefix, options, psuh_usage, 0); |
| 602 | ---- |
| 603 | |
| 604 | This call will modify your `argv` parameter. It will strip the options you |
| 605 | specified in `options` from `argv` and the locations pointed to from `options` |
| 606 | entries will be updated. Be sure to replace your `argc` with the result from |
| 607 | `parse_options()`, or you will be confused if you try to parse `argv` later. |
| 608 | |
| 609 | It's worth noting the special argument `--`. As you may be aware, many Unix |
| 610 | commands use `--` to indicate "end of named parameters" - all parameters after |
| 611 | the `--` are interpreted merely as positional arguments. (This can be handy if |
| 612 | you want to pass as a parameter something which would usually be interpreted as |
| 613 | a flag.) `parse_options()` will terminate parsing when it reaches `--` and give |
| 614 | you the rest of the options afterwards, untouched. |
| 615 | |
| 616 | Now that you have a usage hint, you can teach Git how to show it in the general |
| 617 | command list shown by `git help git` or `git help -a`, which is generated from |
| 618 | `command-list.txt`. Find the line for 'git-pull' so you can add your 'git-psuh' |
| 619 | line above it in alphabetical order. Now, we can add some attributes about the |
| 620 | command which impacts where it shows up in the aforementioned help commands. The |
| 621 | top of `command-list.txt` shares some information about what each attribute |
| 622 | means; in those help pages, the commands are sorted according to these |
| 623 | attributes. `git psuh` is user-facing, or porcelain - so we will mark it as |
| 624 | "mainporcelain". For "mainporcelain" commands, the comments at the top of |
| 625 | `command-list.txt` indicate we can also optionally add an attribute from another |
| 626 | list; since `git psuh` shows some information about the user's workspace but |
| 627 | doesn't modify anything, let's mark it as "info". Make sure to keep your |
| 628 | attributes in the same style as the rest of `command-list.txt` using spaces to |
| 629 | align and delineate them: |
| 630 | |
| 631 | ---- |
| 632 | git-prune-packed plumbingmanipulators |
| 633 | git-psuh mainporcelain info |
| 634 | git-pull mainporcelain remote |
| 635 | git-push mainporcelain remote |
| 636 | ---- |
| 637 | |
| 638 | Build again. Now, when you run with `-h`, you should see your usage printed and |
| 639 | your command terminated before anything else interesting happens. Great! |
| 640 | |
| 641 | Go ahead and commit this one, too. |
| 642 | |
| 643 | [[testing]] |
| 644 | == Testing |
| 645 | |
| 646 | It's important to test your code - even for a little toy command like this one. |
| 647 | Moreover, your patch won't be accepted into the Git tree without tests. Your |
| 648 | tests should: |
| 649 | |
| 650 | * Illustrate the current behavior of the feature |
| 651 | * Prove the current behavior matches the expected behavior |
| 652 | * Ensure the externally-visible behavior isn't broken in later changes |
| 653 | |
| 654 | So let's write some tests. |
| 655 | |
| 656 | Related reading: `t/README` |
| 657 | |
| 658 | [[overview-test-structure]] |
| 659 | === Overview of Testing Structure |
| 660 | |
| 661 | The tests in Git live in `t/` and are named with a 4-digit decimal number using |
| 662 | the schema shown in the Naming Tests section of `t/README`. |
| 663 | |
| 664 | [[write-new-test]] |
| 665 | === Writing Your Test |
| 666 | |
| 667 | Since this a toy command, let's go ahead and name the test with t9999. However, |
| 668 | as many of the family/subcmd combinations are full, best practice seems to be |
| 669 | to find a command close enough to the one you've added and share its naming |
| 670 | space. |
| 671 | |
| 672 | Create a new file `t/t9999-psuh-tutorial.sh`. Begin with the header as so (see |
| 673 | "Writing Tests" and "Source 'test-lib.sh'" in `t/README`): |
| 674 | |
| 675 | ---- |
| 676 | #!/bin/sh |
| 677 | |
| 678 | test_description='git-psuh test |
| 679 | |
| 680 | This test runs git-psuh and makes sure it does not crash.' |
| 681 | |
| 682 | . ./test-lib.sh |
| 683 | ---- |
| 684 | |
| 685 | Tests are framed inside of a `test_expect_success` in order to output TAP |
| 686 | formatted results. Let's make sure that `git psuh` doesn't exit poorly and does |
| 687 | mention the right animal somewhere: |
| 688 | |
| 689 | ---- |
| 690 | test_expect_success 'runs correctly with no args and good output' ' |
| 691 | git psuh >actual && |
| 692 | grep Pony actual |
| 693 | ' |
| 694 | ---- |
| 695 | |
| 696 | Indicate that you've run everything you wanted by adding the following at the |
| 697 | bottom of your script: |
| 698 | |
| 699 | ---- |
| 700 | test_done |
| 701 | ---- |
| 702 | |
| 703 | Make sure you mark your test script executable: |
| 704 | |
| 705 | ---- |
| 706 | $ chmod +x t/t9999-psuh-tutorial.sh |
| 707 | ---- |
| 708 | |
| 709 | You can get an idea of whether you created your new test script successfully |
| 710 | by running `make -C t test-lint`, which will check for things like test number |
| 711 | uniqueness, executable bit, and so on. |
| 712 | |
| 713 | [[local-test]] |
| 714 | === Running Locally |
| 715 | |
| 716 | Let's try and run locally: |
| 717 | |
| 718 | ---- |
| 719 | $ make |
| 720 | $ cd t/ && prove t9999-psuh-tutorial.sh |
| 721 | ---- |
| 722 | |
| 723 | You can run the full test suite and ensure `git-psuh` didn't break anything: |
| 724 | |
| 725 | ---- |
| 726 | $ cd t/ |
| 727 | $ prove -j$(nproc) --shuffle t[0-9]*.sh |
| 728 | ---- |
| 729 | |
| 730 | NOTE: You can also do this with `make test` or use any testing harness which can |
| 731 | speak TAP. `prove` can run concurrently. `-j$(nproc)` runs tests using all |
| 732 | available CPUs in parallel, but the job count can be adjusted as needed. |
| 733 | `shuffle` randomizes the order the tests are run in, which makes them resilient |
| 734 | against unwanted inter-test dependencies. `prove` also makes the output nicer. |
| 735 | |
| 736 | Go ahead and commit this change, as well. |
| 737 | |
| 738 | [[ready-to-share]] |
| 739 | == Getting Ready to Share: Anatomy of a Patch Series |
| 740 | |
| 741 | You may have noticed already that the Git project performs its code reviews via |
| 742 | emailed patches, which are then applied by the maintainer when they are ready |
| 743 | and approved by the community. The Git project does not accept contributions from |
| 744 | pull requests, and the patches emailed for review need to be formatted a |
| 745 | specific way. |
| 746 | |
| 747 | :patch-series: https://lore.kernel.org/git/pull.1218.git.git.1645209647.gitgitgadget@gmail.com/ |
| 748 | :lore: https://lore.kernel.org/git/ |
| 749 | |
| 750 | Before taking a look at how to convert your commits into emailed patches, |
| 751 | let's analyze what the end result, a "patch series", looks like. Here is an |
| 752 | {patch-series}[example] of the summary view for a patch series on the web interface of |
| 753 | the {lore}[Git mailing list archive]: |
| 754 | |
| 755 | ---- |
| 756 | 2022-02-18 18:40 [PATCH 0/3] libify reflog John Cai via GitGitGadget |
| 757 | 2022-02-18 18:40 ` [PATCH 1/3] reflog: libify delete reflog function and helpers John Cai via GitGitGadget |
| 758 | 2022-02-18 19:10 ` Ævar Arnfjörð Bjarmason [this message] |
| 759 | 2022-02-18 19:39 ` Taylor Blau |
| 760 | 2022-02-18 19:48 ` Ævar Arnfjörð Bjarmason |
| 761 | 2022-02-18 19:35 ` Taylor Blau |
| 762 | 2022-02-21 1:43 ` John Cai |
| 763 | 2022-02-21 1:50 ` Taylor Blau |
| 764 | 2022-02-23 19:50 ` John Cai |
| 765 | 2022-02-18 20:00 ` // other replies elided |
| 766 | 2022-02-18 18:40 ` [PATCH 2/3] reflog: call reflog_delete from reflog.c John Cai via GitGitGadget |
| 767 | 2022-02-18 19:15 ` Ævar Arnfjörð Bjarmason |
| 768 | 2022-02-18 20:26 ` Junio C Hamano |
| 769 | 2022-02-18 18:40 ` [PATCH 3/3] stash: call reflog_delete from reflog.c John Cai via GitGitGadget |
| 770 | 2022-02-18 19:20 ` Ævar Arnfjörð Bjarmason |
| 771 | 2022-02-19 0:21 ` Taylor Blau |
| 772 | 2022-02-22 2:36 ` John Cai |
| 773 | 2022-02-22 10:51 ` Ævar Arnfjörð Bjarmason |
| 774 | 2022-02-18 19:29 ` [PATCH 0/3] libify reflog Ævar Arnfjörð Bjarmason |
| 775 | 2022-02-22 18:30 ` [PATCH v2 0/3] libify reflog John Cai via GitGitGadget |
| 776 | 2022-02-22 18:30 ` [PATCH v2 1/3] stash: add test to ensure reflog --rewrite --updatref behavior John Cai via GitGitGadget |
| 777 | 2022-02-23 8:54 ` Ævar Arnfjörð Bjarmason |
| 778 | 2022-02-23 21:27 ` Junio C Hamano |
| 779 | // continued |
| 780 | ---- |
| 781 | |
| 782 | We can note a few things: |
| 783 | |
| 784 | - Each commit is sent as a separate email, with the commit message title as |
| 785 | subject, prefixed with "[PATCH _i_/_n_]" for the _i_-th commit of an |
| 786 | _n_-commit series. |
| 787 | - Each patch is sent as a reply to an introductory email called the _cover |
| 788 | letter_ of the series, prefixed "[PATCH 0/_n_]". |
| 789 | - Subsequent iterations of the patch series are labelled "PATCH v2", "PATCH |
| 790 | v3", etc. in place of "PATCH". For example, "[PATCH v2 1/3]" would be the first of |
| 791 | three patches in the second iteration. Each iteration is sent with a new cover |
| 792 | letter (like "[PATCH v2 0/3]" above), itself a reply to the cover letter of the |
| 793 | previous iteration (more on that below). |
| 794 | |
| 795 | NOTE: A single-patch topic is sent with "[PATCH]", "[PATCH v2]", etc. without |
| 796 | _i_/_n_ numbering (in the above thread overview, no single-patch topic appears, |
| 797 | though). |
| 798 | |
| 799 | [[cover-letter]] |
| 800 | === The cover letter |
| 801 | |
| 802 | In addition to an email per patch, the Git community also expects your patches |
| 803 | to come with a cover letter. This is an important component of change |
| 804 | submission as it explains to the community from a high level what you're trying |
| 805 | to do, and why, in a way that's more apparent than just looking at your |
| 806 | patches. |
| 807 | |
| 808 | The title of your cover letter should be something which succinctly covers the |
| 809 | purpose of your entire topic branch. It's often in the imperative mood, just |
| 810 | like our commit message titles. Here is how we'll title our series: |
| 811 | |
| 812 | --- |
| 813 | Add the 'psuh' command |
| 814 | --- |
| 815 | |
| 816 | The body of the cover letter is used to give additional context to reviewers. |
| 817 | Be sure to explain anything your patches don't make clear on their own, but |
| 818 | remember that since the cover letter is not recorded in the commit history, |
| 819 | anything that might be useful to future readers of the repository's history |
| 820 | should also be in your commit messages. |
| 821 | |
| 822 | Here's an example body for `psuh`: |
| 823 | |
| 824 | ---- |
| 825 | Our internal metrics indicate widespread interest in the command |
| 826 | git-psuh - that is, many users are trying to use it, but finding it is |
| 827 | unavailable, using some unknown workaround instead. |
| 828 | |
| 829 | The following handful of patches add the psuh command and implement some |
| 830 | handy features on top of it. |
| 831 | |
| 832 | This patchset is part of the MyFirstContribution tutorial and should not |
| 833 | be merged. |
| 834 | ---- |
| 835 | |
| 836 | At this point the tutorial diverges, in order to demonstrate two |
| 837 | different methods of formatting your patchset and getting it reviewed. |
| 838 | |
| 839 | The first method to be covered is GitGitGadget, which is useful for those |
| 840 | already familiar with GitHub's common pull request workflow. This method |
| 841 | requires a GitHub account. |
| 842 | |
| 843 | The second method to be covered is `git send-email`, which can give slightly |
| 844 | more fine-grained control over the emails to be sent. This method requires some |
| 845 | setup which can change depending on your system and will not be covered in this |
| 846 | tutorial. |
| 847 | |
| 848 | Regardless of which method you choose, your engagement with reviewers will be |
| 849 | the same; the review process will be covered after the sections on GitGitGadget |
| 850 | and `git send-email`. |
| 851 | |
| 852 | [[howto-ggg]] |
| 853 | == Sending Patches via GitGitGadget |
| 854 | |
| 855 | One option for sending patches is to follow a typical pull request workflow and |
| 856 | send your patches out via GitGitGadget. GitGitGadget is a tool created by |
| 857 | Johannes Schindelin to make life as a Git contributor easier for those used to |
| 858 | the GitHub PR workflow. It allows contributors to open pull requests against its |
| 859 | mirror of the Git project, and does some magic to turn the PR into a set of |
| 860 | emails and send them out for you. It also runs the Git continuous integration |
| 861 | suite for you. It's documented at https://gitgitgadget.github.io/. |
| 862 | |
| 863 | [[create-fork]] |
| 864 | === Forking `git/git` on GitHub |
| 865 | |
| 866 | Before you can send your patch off to be reviewed using GitGitGadget, you will |
| 867 | need to fork the Git project and upload your changes. First thing - make sure |
| 868 | you have a GitHub account. |
| 869 | |
| 870 | Head to the https://github.com/git/git[GitHub mirror] and look for the Fork |
| 871 | button. Place your fork wherever you deem appropriate and create it. |
| 872 | |
| 873 | [[upload-to-fork]] |
| 874 | === Uploading to Your Own Fork |
| 875 | |
| 876 | To upload your branch to your own fork, you'll need to add the new fork as a |
| 877 | remote. You can use `git remote -v` to show the remotes you have added already. |
| 878 | From your new fork's page on GitHub, you can press "Clone or download" to get |
| 879 | the URL; then you need to run the following to add, replacing your own URL and |
| 880 | remote name for the examples provided: |
| 881 | |
| 882 | ---- |
| 883 | $ git remote add remotename git@github.com:remotename/git.git |
| 884 | ---- |
| 885 | |
| 886 | or to use the HTTPS URL: |
| 887 | |
| 888 | ---- |
| 889 | $ git remote add remotename https://github.com/remotename/git/.git |
| 890 | ---- |
| 891 | |
| 892 | Run `git remote -v` again and you should see the new remote showing up. |
| 893 | `git fetch remotename` (with the real name of your remote replaced) in order to |
| 894 | get ready to push. |
| 895 | |
| 896 | Next, double-check that you've been doing all your development in a new branch |
| 897 | by running `git branch`. If you didn't, now is a good time to move your new |
| 898 | commits to their own branch. |
| 899 | |
| 900 | As mentioned briefly at the beginning of this document, we are basing our work |
| 901 | on `master`, so go ahead and update as shown below, or using your preferred |
| 902 | workflow. |
| 903 | |
| 904 | ---- |
| 905 | $ git checkout master |
| 906 | $ git pull -r |
| 907 | $ git rebase master psuh |
| 908 | ---- |
| 909 | |
| 910 | Finally, you're ready to push your new topic branch! (Due to our branch and |
| 911 | command name choices, be careful when you type the command below.) |
| 912 | |
| 913 | ---- |
| 914 | $ git push remotename psuh |
| 915 | ---- |
| 916 | |
| 917 | Now you should be able to go and check out your newly created branch on GitHub. |
| 918 | |
| 919 | [[send-pr-ggg]] |
| 920 | === Sending a PR to GitGitGadget |
| 921 | |
| 922 | In order to have your code tested and formatted for review, you need to start by |
| 923 | opening a Pull Request against either `gitgitgadget/git` or `git/git`. Head to |
| 924 | https://github.com/gitgitgadget/git or https://github.com/git/git and open a PR |
| 925 | either with the "New pull request" button or the convenient "Compare & pull |
| 926 | request" button that may appear with the name of your newly pushed branch. |
| 927 | |
| 928 | The differences between using `gitgitgadget/git` and `git/git` as your base can |
| 929 | be found [here](https://gitgitgadget.github.io/#should-i-use-gitgitgadget-on-gitgitgadgets-git-fork-or-on-gits-github-mirror) |
| 930 | |
| 931 | Review the PR's title and description, as they're used by GitGitGadget |
| 932 | respectively as the subject and body of the cover letter for your change. Refer |
| 933 | to <<cover-letter,"The cover letter">> above for advice on how to title your |
| 934 | submission and what content to include in the description. |
| 935 | |
| 936 | NOTE: For single-patch contributions, your commit message should already be |
| 937 | meaningful and explain at a high level the purpose (what is happening and why) |
| 938 | of your patch, so you usually do not need any additional context. In that case, |
| 939 | remove the PR description that GitHub automatically generates from your commit |
| 940 | message (your PR description should be empty). If you do need to supply even |
| 941 | more context, you can do so in that space and it will be appended to the email |
| 942 | that GitGitGadget will send, between the three-dash line and the diffstat |
| 943 | (see <<single-patch,Bonus Chapter: One-Patch Changes>> for how this looks once |
| 944 | submitted). |
| 945 | |
| 946 | When you're happy, submit your pull request. |
| 947 | |
| 948 | [[run-ci-ggg]] |
| 949 | === Running CI and Getting Ready to Send |
| 950 | |
| 951 | If it's your first time using GitGitGadget (which is likely, as you're using |
| 952 | this tutorial) then someone will need to give you permission to use the tool. |
| 953 | As mentioned in the GitGitGadget documentation, you just need someone who |
| 954 | already uses it to comment on your PR with `/allow <username>`. GitGitGadget |
| 955 | will automatically run your PRs through the CI even without the permission given |
| 956 | but you will not be able to `/submit` your changes until someone allows you to |
| 957 | use the tool. |
| 958 | |
| 959 | NOTE: You can typically find someone who can `/allow` you on GitGitGadget by |
| 960 | either examining recent pull requests where someone has been granted `/allow` |
| 961 | (https://github.com/gitgitgadget/git/pulls?utf8=%E2%9C%93&q=is%3Apr+is%3Aopen+%22%2Fallow%22[Search: |
| 962 | is:pr is:open "/allow"]), in which case both the author and the person who |
| 963 | granted the `/allow` can now `/allow` you, or by inquiring on the |
| 964 | https://web.libera.chat/#git-devel[#git-devel] IRC channel on Libera Chat |
| 965 | linking your pull request and asking for someone to `/allow` you. |
| 966 | |
| 967 | If the CI fails, you can update your changes with `git rebase -i` and push your |
| 968 | branch again: |
| 969 | |
| 970 | ---- |
| 971 | $ git push -f remotename psuh |
| 972 | ---- |
| 973 | |
| 974 | In fact, you should continue to make changes this way up until the point when |
| 975 | your patch is accepted into `next`. |
| 976 | |
| 977 | //// |
| 978 | TODO https://github.com/gitgitgadget/gitgitgadget/issues/83 |
| 979 | It'd be nice to be able to verify that the patch looks good before sending it |
| 980 | to everyone on Git mailing list. |
| 981 | [[check-work-ggg]] |
| 982 | === Check Your Work |
| 983 | //// |
| 984 | |
| 985 | [[send-mail-ggg]] |
| 986 | === Sending Your Patches |
| 987 | |
| 988 | Now that your CI is passing and someone has granted you permission to use |
| 989 | GitGitGadget with the `/allow` command, sending out for review is as simple as |
| 990 | commenting on your PR with `/submit`. |
| 991 | |
| 992 | [[responding-ggg]] |
| 993 | === Updating With Comments |
| 994 | |
| 995 | Skip ahead to <<reviewing,Responding to Reviews>> for information on how to |
| 996 | reply to review comments you will receive on the mailing list. |
| 997 | |
| 998 | Once you have your branch again in the shape you want following all review |
| 999 | comments, you can submit again: |
| 1000 | |
| 1001 | ---- |
| 1002 | $ git push -f remotename psuh |
| 1003 | ---- |
| 1004 | |
| 1005 | Next, go look at your pull request against GitGitGadget; you should see the CI |
| 1006 | has been kicked off again. Now while the CI is running is a good time for you |
| 1007 | to modify your description at the top of the pull request thread; it will be |
| 1008 | used again as the cover letter. You should use this space to describe what |
| 1009 | has changed since your previous version, so that your reviewers have some idea |
| 1010 | of what they're looking at. When the CI is done running, you can comment once |
| 1011 | more with `/submit` - GitGitGadget will automatically add a v2 mark to your |
| 1012 | changes. |
| 1013 | |
| 1014 | [[howto-git-send-email]] |
| 1015 | == Sending Patches with `git send-email` |
| 1016 | |
| 1017 | If you don't want to use GitGitGadget, you can also use Git itself to mail your |
| 1018 | patches. Some benefits of using Git this way include finer grained control of |
| 1019 | subject line (for example, being able to use the tag [RFC PATCH] in the subject) |
| 1020 | and being able to send a ``dry run'' mail to yourself to ensure it all looks |
| 1021 | good before going out to the list. |
| 1022 | |
| 1023 | [[setup-git-send-email]] |
| 1024 | === Prerequisite: Setting Up `git send-email` |
| 1025 | |
| 1026 | Configuration for `send-email` can vary based on your operating system and email |
| 1027 | provider, and so will not be covered in this tutorial, beyond stating that in |
| 1028 | many distributions of Linux, `git-send-email` is not packaged alongside the |
| 1029 | typical `git` install. You may need to install this additional package; there |
| 1030 | are a number of resources online to help you do so. You will also need to |
| 1031 | determine the right way to configure it to use your SMTP server; again, as this |
| 1032 | configuration can change significantly based on your system and email setup, it |
| 1033 | is out of scope for the context of this tutorial. |
| 1034 | |
| 1035 | [[format-patch]] |
| 1036 | === Preparing Initial Patchset |
| 1037 | |
| 1038 | Sending emails with Git is a two-part process; before you can prepare the emails |
| 1039 | themselves, you'll need to prepare the patches. Luckily, this is pretty simple: |
| 1040 | |
| 1041 | ---- |
| 1042 | $ git format-patch --cover-letter -o psuh/ --base=auto psuh@{u}..psuh |
| 1043 | ---- |
| 1044 | |
| 1045 | . The `--cover-letter` option tells `format-patch` to create a |
| 1046 | cover letter template for you. You will need to fill in the |
| 1047 | template before you're ready to send - but for now, the template |
| 1048 | will be next to your other patches. |
| 1049 | |
| 1050 | . The `-o psuh/` option tells `format-patch` to place the patch |
| 1051 | files into a directory. This is useful because `git send-email` |
| 1052 | can take a directory and send out all the patches from there. |
| 1053 | |
| 1054 | . The `--base=auto` option tells the command to record the "base |
| 1055 | commit", on which the recipient is expected to apply the patch |
| 1056 | series. The `auto` value will cause `format-patch` to compute |
| 1057 | the base commit automatically, which is the merge base of tip |
| 1058 | commit of the remote-tracking branch and the specified revision |
| 1059 | range. |
| 1060 | |
| 1061 | . The `psuh@{u}..psuh` option tells `format-patch` to generate |
| 1062 | patches for the commits you created on the `psuh` branch since it |
| 1063 | forked from its upstream (which is `origin/master` if you |
| 1064 | followed the example in the "Set up your workspace" section). If |
| 1065 | you are already on the `psuh` branch, you can just say `@{u}`, |
| 1066 | which means "commits on the current branch since it forked from |
| 1067 | its upstream", which is the same thing. |
| 1068 | |
| 1069 | The command will make one patch file per commit. After you |
| 1070 | run, you can go have a look at each of the patches with your favorite text |
| 1071 | editor and make sure everything looks alright; however, it's not recommended to |
| 1072 | make code fixups via the patch file. It's a better idea to make the change the |
| 1073 | normal way using `git rebase -i` or by adding a new commit than by modifying a |
| 1074 | patch. |
| 1075 | |
| 1076 | NOTE: Optionally, you can also use the `--rfc` flag to prefix your patch subject |
| 1077 | with ``[RFC PATCH]'' instead of ``[PATCH]''. RFC stands for ``request for |
| 1078 | comments'' and indicates that while your code isn't quite ready for submission, |
| 1079 | you'd like to begin the code review process. This can also be used when your |
| 1080 | patch is a proposal, but you aren't sure whether the community wants to solve |
| 1081 | the problem with that approach or not - to conduct a sort of design review. You |
| 1082 | may also see on the list patches marked ``WIP'' - this means they are incomplete |
| 1083 | but want reviewers to look at what they have so far. You can add this flag with |
| 1084 | `--subject-prefix=WIP`. |
| 1085 | |
| 1086 | Check and make sure that your patches and cover letter template exist in the |
| 1087 | directory you specified - you're nearly ready to send out your review! |
| 1088 | |
| 1089 | [[preparing-cover-letter]] |
| 1090 | === Preparing Email |
| 1091 | |
| 1092 | Since you invoked `format-patch` with `--cover-letter`, you've already got a |
| 1093 | cover letter template ready. Open it up in your favorite editor. |
| 1094 | |
| 1095 | You should see a number of headers present already. Check that your `From:` |
| 1096 | header is correct. Then modify your `Subject:` (see <<cover-letter,above>> for |
| 1097 | how to choose good title for your patch series): |
| 1098 | |
| 1099 | ---- |
| 1100 | Subject: [PATCH 0/7] Add the 'psuh' command |
| 1101 | ---- |
| 1102 | |
| 1103 | Make sure you retain the ``[PATCH 0/X]'' part; that's what indicates to the Git |
| 1104 | community that this email is the beginning of a patch series, and many |
| 1105 | reviewers filter their email for this type of flag. |
| 1106 | |
| 1107 | You'll need to add some extra parameters when you invoke `git send-email` to add |
| 1108 | the cover letter. |
| 1109 | |
| 1110 | Next you'll have to fill out the body of your cover letter. Again, see |
| 1111 | <<cover-letter,above>> for what content to include. |
| 1112 | |
| 1113 | The template created by `git format-patch --cover-letter` includes a diffstat. |
| 1114 | This gives reviewers a summary of what they're in for when reviewing your topic. |
| 1115 | The one generated for `psuh` from the sample implementation looks like this: |
| 1116 | |
| 1117 | ---- |
| 1118 | Documentation/git-psuh.adoc | 40 +++++++++++++++++++++ |
| 1119 | Makefile | 1 + |
| 1120 | builtin.h | 1 + |
| 1121 | builtin/psuh.c | 73 ++++++++++++++++++++++++++++++++++++++ |
| 1122 | git.c | 1 + |
| 1123 | t/t9999-psuh-tutorial.sh | 12 +++++++ |
| 1124 | 6 files changed, 128 insertions(+) |
| 1125 | create mode 100644 Documentation/git-psuh.adoc |
| 1126 | create mode 100644 builtin/psuh.c |
| 1127 | create mode 100755 t/t9999-psuh-tutorial.sh |
| 1128 | ---- |
| 1129 | |
| 1130 | Finally, the letter will include the version of Git used to generate the |
| 1131 | patches. You can leave that string alone. |
| 1132 | |
| 1133 | [[sending-git-send-email]] |
| 1134 | === Sending Email |
| 1135 | |
| 1136 | At this point you should have a directory `psuh/` which is filled with your |
| 1137 | patches and a cover letter. Time to mail it out! You can send it like this: |
| 1138 | |
| 1139 | ---- |
| 1140 | $ git send-email --to=target@example.com psuh/*.patch |
| 1141 | ---- |
| 1142 | |
| 1143 | NOTE: Check `git help send-email` for some other options which you may find |
| 1144 | valuable, such as changing the Reply-to address or adding more CC and BCC lines. |
| 1145 | |
| 1146 | :contrib-scripts: footnoteref:[contrib-scripts,Scripts under `contrib/` are + |
| 1147 | not part of the core `git` binary and must be called directly. Clone the Git + |
| 1148 | codebase and run `perl contrib/contacts/git-contacts`.] |
| 1149 | |
| 1150 | NOTE: If you're not sure whom to CC, running `contrib/contacts/git-contacts` can |
| 1151 | list potential reviewers. In addition, you can do `git send-email |
| 1152 | --cc-cmd='perl contrib/contacts/git-contacts' feature/*.patch`{contrib-scripts} to |
| 1153 | automatically pass this list of emails to `send-email`. |
| 1154 | |
| 1155 | NOTE: When you are sending a real patch, it will go to git@vger.kernel.org - but |
| 1156 | please don't send your patchset from the tutorial to the real mailing list! For |
| 1157 | now, you can send it to yourself, to make sure you understand how it will look. |
| 1158 | |
| 1159 | NOTE: After sending your patches, you can confirm that they reached the mailing |
| 1160 | list by visiting https://lore.kernel.org/git/. Use the search bar to find your |
| 1161 | name or the subject of your patch. If it appears, your email was successfully |
| 1162 | delivered. |
| 1163 | |
| 1164 | After you run the command above, you will be presented with an interactive |
| 1165 | prompt for each patch that's about to go out. This gives you one last chance to |
| 1166 | edit or quit sending something (but again, don't edit code this way). Once you |
| 1167 | press `y` or `a` at these prompts your emails will be sent! Congratulations! |
| 1168 | |
| 1169 | Awesome, now the community will drop everything and review your changes. (Just |
| 1170 | kidding - be patient!) |
| 1171 | |
| 1172 | [[v2-git-send-email]] |
| 1173 | === Sending v2 |
| 1174 | |
| 1175 | This section will focus on how to send a v2 of your patchset. To learn what |
| 1176 | should go into v2, skip ahead to <<reviewing,Responding to Reviews>> for |
| 1177 | information on how to handle comments from reviewers. |
| 1178 | |
| 1179 | We'll reuse our `psuh` topic branch for v2. Before we make any changes, we'll |
| 1180 | mark the tip of our v1 branch for easy reference: |
| 1181 | |
| 1182 | ---- |
| 1183 | $ git checkout psuh |
| 1184 | $ git branch psuh-v1 |
| 1185 | ---- |
| 1186 | |
| 1187 | Refine your patch series by using `git rebase -i` to adjust commits based upon |
| 1188 | reviewer comments. Once the patch series is ready for submission, generate your |
| 1189 | patches again, but with some new flags: |
| 1190 | |
| 1191 | ---- |
| 1192 | $ git format-patch -v2 --cover-letter -o psuh/ --range-diff master..psuh-v1 master.. |
| 1193 | ---- |
| 1194 | |
| 1195 | The `--range-diff master..psuh-v1` parameter tells `format-patch` to include a |
| 1196 | range-diff between `psuh-v1` and `psuh` in the cover letter (see |
| 1197 | linkgit:git-range-diff[1]). This helps tell reviewers about the differences |
| 1198 | between your v1 and v2 patches. |
| 1199 | |
| 1200 | The `-v2` parameter tells `format-patch` to output your patches |
| 1201 | as version "2". For instance, you may notice that your v2 patches are |
| 1202 | all named like `v2-000n-my-commit-subject.patch`. `-v2` will also format |
| 1203 | your patches by prefixing them with "[PATCH v2]" instead of "[PATCH]", |
| 1204 | and your range-diff will be prefaced with "Range-diff against v1". |
| 1205 | |
| 1206 | After you run this command, `format-patch` will output the patches to the `psuh/` |
| 1207 | directory, alongside the v1 patches. Using a single directory makes it easy to |
| 1208 | refer to the old v1 patches while proofreading the v2 patches, but you will need |
| 1209 | to be careful to send out only the v2 patches. We will use a pattern like |
| 1210 | `psuh/v2-*.patch` (not `psuh/*.patch`, which would match v1 and v2 patches). |
| 1211 | |
| 1212 | Edit your cover letter again. Now is a good time to mention what's different |
| 1213 | between your last version and now, if it's something significant. You do not |
| 1214 | need the exact same body in your second cover letter; focus on explaining to |
| 1215 | reviewers the changes you've made that may not be as visible. |
| 1216 | |
| 1217 | You will also need to go and find the Message-ID of your previous cover letter. |
| 1218 | You can either note it when you send the first series, from the output of `git |
| 1219 | send-email`, or you can look it up on the |
| 1220 | https://lore.kernel.org/git[mailing list]. Find your cover letter in the |
| 1221 | archives, click on it, then click "permalink" or "raw" to reveal the Message-ID |
| 1222 | header. It should match: |
| 1223 | |
| 1224 | ---- |
| 1225 | Message-ID: <foo.12345.author@example.com> |
| 1226 | ---- |
| 1227 | |
| 1228 | Your Message-ID is `<foo.12345.author@example.com>`. This example will be used |
| 1229 | below as well; make sure to replace it with the correct Message-ID for your |
| 1230 | **previous cover letter** - that is, if you're sending v2, use the Message-ID |
| 1231 | from v1; if you're sending v3, use the Message-ID from v2. |
| 1232 | |
| 1233 | While you're looking at the email, you should also note who is CC'd, as it's |
| 1234 | common practice in the mailing list to keep all CCs on a thread. You can add |
| 1235 | these CC lines directly to your cover letter with a line like so in the header |
| 1236 | (before the Subject line): |
| 1237 | |
| 1238 | ---- |
| 1239 | CC: author@example.com, Othe R <other@example.com> |
| 1240 | ---- |
| 1241 | |
| 1242 | Now send the emails again, paying close attention to which messages you pass in |
| 1243 | to the command: |
| 1244 | |
| 1245 | ---- |
| 1246 | $ git send-email --to=target@example.com |
| 1247 | --in-reply-to="<foo.12345.author@example.com>" |
| 1248 | psuh/v2-*.patch |
| 1249 | ---- |
| 1250 | |
| 1251 | [[single-patch]] |
| 1252 | === Bonus Chapter: One-Patch Changes |
| 1253 | |
| 1254 | In some cases, your very small change may consist of only one patch. When that |
| 1255 | happens, you only need to send one email. Your commit message should already be |
| 1256 | meaningful and explain at a high level the purpose (what is happening and why) |
| 1257 | of your patch, but if you need to supply even more context, you can do so below |
| 1258 | the `---` in your patch. Take the example below, which was generated with `git |
| 1259 | format-patch` on a single commit, and then edited to add the content between |
| 1260 | the `---` and the diffstat. |
| 1261 | |
| 1262 | ---- |
| 1263 | From 1345bbb3f7ac74abde040c12e737204689a72723 Mon Sep 17 00:00:00 2001 |
| 1264 | From: A U Thor <author@example.com> |
| 1265 | Date: Thu, 18 Apr 2019 15:11:02 -0700 |
| 1266 | Subject: [PATCH] README: change the grammar |
| 1267 | |
| 1268 | I think it looks better this way. This part of the commit message will |
| 1269 | end up in the commit-log. |
| 1270 | |
| 1271 | Signed-off-by: A U Thor <author@example.com> |
| 1272 | --- |
| 1273 | Let's have a wild discussion about grammar on the mailing list. This |
| 1274 | part of my email will never end up in the commit log. Here is where I |
| 1275 | can add additional context to the mailing list about my intent, outside |
| 1276 | of the context of the commit log. This section was added after `git |
| 1277 | format-patch` was run, by editing the patch file in a text editor. |
| 1278 | |
| 1279 | README.md | 2 +- |
| 1280 | 1 file changed, 1 insertion(+), 1 deletion(-) |
| 1281 | |
| 1282 | diff --git a/README.md b/README.md |
| 1283 | index 88f126184c..38da593a60 100644 |
| 1284 | --- a/README.md |
| 1285 | +++ b/README.md |
| 1286 | @@ -3,7 +3,7 @@ |
| 1287 | Git - fast, scalable, distributed revision control system |
| 1288 | ========================================================= |
| 1289 | |
| 1290 | -Git is a fast, scalable, distributed revision control system with an |
| 1291 | +Git is a fast, scalable, and distributed revision control system with an |
| 1292 | unusually rich command set that provides both high-level operations |
| 1293 | and full access to internals. |
| 1294 | |
| 1295 | -- |
| 1296 | 2.21.0.392.gf8f6787159e-goog |
| 1297 | ---- |
| 1298 | |
| 1299 | [[now-what]] |
| 1300 | == My Patch Got Emailed - Now What? |
| 1301 | |
| 1302 | Please give reviewers enough time to process your initial patch before |
| 1303 | sending an updated version. That is, resist the temptation to send a new |
| 1304 | version immediately, because others may have already started reviewing |
| 1305 | your initial version. |
| 1306 | |
| 1307 | While waiting for review comments, you may find mistakes in your initial |
| 1308 | patch, or perhaps realize a different and better way to achieve the goal |
| 1309 | of the patch. In this case you may communicate your findings to other |
| 1310 | reviewers as follows: |
| 1311 | |
| 1312 | - If the mistakes you found are minor, send a reply to your patch as if |
| 1313 | you were a reviewer and mention that you will fix them in an |
| 1314 | updated version. |
| 1315 | |
| 1316 | - On the other hand, if you think you want to change the course so |
| 1317 | drastically that reviews on the initial patch would be a waste of |
| 1318 | time (for everyone involved), retract the patch immediately with |
| 1319 | a reply like "I am working on a much better approach, so please |
| 1320 | ignore this patch and wait for the updated version." |
| 1321 | |
| 1322 | Now, the above is a good practice if you sent your initial patch |
| 1323 | prematurely without polish. But a better approach of course is to avoid |
| 1324 | sending your patch prematurely in the first place. |
| 1325 | |
| 1326 | Please be considerate of the time needed by reviewers to examine each |
| 1327 | new version of your patch. Rather than seeing the initial version right |
| 1328 | now (followed by several "oops, I like this version better than the |
| 1329 | previous one" patches over 2 days), reviewers would strongly prefer if a |
| 1330 | single polished version came 2 days later instead, and that version with |
| 1331 | fewer mistakes were the only one they would need to review. |
| 1332 | |
| 1333 | |
| 1334 | [[reviewing]] |
| 1335 | === Responding to Reviews |
| 1336 | |
| 1337 | After a few days, you will hopefully receive a reply to your patchset with some |
| 1338 | comments. Woohoo! Now you can get back to work. |
| 1339 | |
| 1340 | It's good manners to reply to each comment, notifying the reviewer that you have |
| 1341 | made the change suggested, feel the original is better, or that the comment |
| 1342 | inspired you to do something a new way which is superior to both the original |
| 1343 | and the suggested change. This way reviewers don't need to inspect your v2 to |
| 1344 | figure out whether you implemented their comment or not. |
| 1345 | |
| 1346 | Reviewers may ask you about what you wrote in the patchset, either in |
| 1347 | the proposed commit log message or in the changes themselves. You |
| 1348 | should answer these questions in your response messages, but often the |
| 1349 | reason why reviewers asked these questions to understand what you meant |
| 1350 | to write is because your patchset needed clarification to be understood. |
| 1351 | |
| 1352 | Do not be satisfied by just answering their questions in your response |
| 1353 | and hear them say that they now understand what you wanted to say. |
| 1354 | Update your patches to clarify the points reviewers had trouble with, |
| 1355 | and prepare your v2; the words you used to explain your v1 to answer |
| 1356 | reviewers' questions may be useful thing to use. Your goal is to make |
| 1357 | your v2 clear enough so that it becomes unnecessary for you to give the |
| 1358 | same explanation to the next person who reads it. |
| 1359 | |
| 1360 | If you are going to push back on a comment, be polite and explain why you feel |
| 1361 | your original is better; be prepared that the reviewer may still disagree with |
| 1362 | you, and the rest of the community may weigh in on one side or the other. As |
| 1363 | with all code reviews, it's important to keep an open mind to doing something a |
| 1364 | different way than you originally planned; other reviewers have a different |
| 1365 | perspective on the project than you do, and may be thinking of a valid side |
| 1366 | effect which had not occurred to you. It is always okay to ask for clarification |
| 1367 | if you aren't sure why a change was suggested, or what the reviewer is asking |
| 1368 | you to do. |
| 1369 | |
| 1370 | Make sure your email client has a plaintext email mode and it is turned on; the |
| 1371 | Git list rejects HTML email. Please also follow the mailing list etiquette |
| 1372 | outlined in the |
| 1373 | https://kernel.googlesource.com/pub/scm/git/git/+/todo/MaintNotes[Maintainer's |
| 1374 | Note], which are similar to etiquette rules in most open source communities |
| 1375 | surrounding bottom-posting and inline replies. |
| 1376 | |
| 1377 | When you're making changes to your code, it is cleanest - that is, the resulting |
| 1378 | commits are easiest to look at - if you use `git rebase -i` (interactive |
| 1379 | rebase). Take a look at this |
| 1380 | https://www.oreilly.com/library/view/git-pocket-guide/9781449327507/ch10.html[overview] |
| 1381 | from O'Reilly. The general idea is to modify each commit which requires changes; |
| 1382 | this way, instead of having a patch A with a mistake, a patch B which was fine |
| 1383 | and required no upstream reviews in v1, and a patch C which fixes patch A for |
| 1384 | v2, you can just ship a v2 with a correct patch A and correct patch B. This is |
| 1385 | changing history, but since it's local history which you haven't shared with |
| 1386 | anyone, that is okay for now! (Later, it may not make sense to do this; take a |
| 1387 | look at the section below this one for some context.) |
| 1388 | |
| 1389 | [[after-approval]] |
| 1390 | === After Review Approval |
| 1391 | |
| 1392 | The Git project has four integration branches: `seen`, `next`, `master`, and |
| 1393 | `maint`. Your change will be placed into `seen` fairly early on by the maintainer |
| 1394 | while it is still in the review process; from there, when it is ready for wider |
| 1395 | testing, it will be merged into `next`. Plenty of early testers use `next` and |
| 1396 | may report issues. Eventually, changes in `next` will make it to `master`, |
| 1397 | which is typically considered stable. Finally, when a new release is cut, |
| 1398 | `maint` is used to base bugfixes onto. As mentioned at the beginning of this |
| 1399 | document, you can read `Documents/SubmittingPatches` for some more info about |
| 1400 | the use of the various integration branches. |
| 1401 | |
| 1402 | Back to now: your code has been lauded by the upstream reviewers. It is perfect. |
| 1403 | It is ready to be accepted. You don't need to do anything else; the maintainer |
| 1404 | will merge your topic branch to `next` and life is good. |
| 1405 | |
| 1406 | However, if you discover it isn't so perfect after this point, you may need to |
| 1407 | take some special steps depending on where you are in the process. |
| 1408 | |
| 1409 | If the maintainer has announced in the "What's cooking in git.git" email that |
| 1410 | your topic is marked for `next` - that is, that they plan to merge it to `next` |
| 1411 | but have not yet done so - you should send an email asking the maintainer to |
| 1412 | wait a little longer: "I've sent v4 of my series and you marked it for `next`, |
| 1413 | but I need to change this and that - please wait for v5 before you merge it." |
| 1414 | |
| 1415 | If the topic has already been merged to `next`, rather than modifying your |
| 1416 | patches with `git rebase -i`, you should make further changes incrementally - |
| 1417 | that is, with another commit, based on top of the maintainer's topic branch as |
| 1418 | detailed in https://github.com/gitster/git. Your work is still in the same topic |
| 1419 | but is now incremental, rather than a wholesale rewrite of the topic branch. |
| 1420 | |
| 1421 | The topic branches in the maintainer's GitHub are mirrored in GitGitGadget, so |
| 1422 | if you're sending your reviews out that way, you should be sure to open your PR |
| 1423 | against the appropriate GitGitGadget/Git branch. |
| 1424 | |
| 1425 | If you're using `git send-email`, you can use it the same way as before, but you |
| 1426 | should generate your diffs from `<topic>..<mybranch>` and base your work on |
| 1427 | `<topic>` instead of `master`. |