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1 | Contributing To Busybox |
2 | ======================= |
3 | |
4 | This document describes what you need to do to contribute to Busybox, where |
5 | you can help, guidelines on testing, and how to submit a well-formed patch |
6 | that is more likely to be accepted. |
7 | |
8 | The Busybox home page is at: http://busybox.net/ |
9 | |
10 | |
11 | |
12 | Pre-Contribution Checklist |
13 | -------------------------- |
14 | |
15 | So you want to contribute to Busybox, eh? Great, wonderful, glad you want to |
16 | help. However, before you dive in, headlong and hotfoot, there are some things |
17 | you need to do: |
18 | |
19 | |
20 | Checkout the Latest Code from CVS |
21 | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
22 | |
23 | This is a necessary first step. Please do not try to work with the last |
24 | released version, as there is a good chance that somebody has already fixed |
25 | the bug you found. Somebody might have even added the feature you had in mind. |
26 | Don't make your work obsolete before you start! |
27 | |
28 | For information on how to check out Busybox from CVS, please look at the |
29 | following links: |
30 | |
31 | http://busybox.net/cvs_anon.html |
32 | http://busybox.net/cvs_howto.html |
33 | |
34 | |
35 | Read the Mailing List |
36 | ~~~~~~~~~~~~~~~~~~~~~ |
37 | |
38 | No one is required to read the entire archives of the mailing list, but you |
39 | should at least read up on what people have been talking about lately. If |
40 | you've recently discovered a problem, chances are somebody else has too. If |
41 | you're the first to discover a problem, post a message and let the rest of us |
42 | know. |
43 | |
44 | Archives can be found here: |
45 | |
46 | http://busybox.net/lists/busybox/ |
47 | |
48 | If you have a serious interest in Busybox, i.e., you are using it day-to-day or |
49 | as part of an embedded project, it would be a good idea to join the mailing |
50 | list. |
51 | |
52 | A web-based sign-up form can be found here: |
53 | |
54 | http://busybox.net/mailman/listinfo/busybox |
55 | |
56 | |
57 | Coordinate with the Applet Maintainer |
58 | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
59 | |
60 | Some (not all) of the applets in Busybox are "owned" by a maintainer who has |
61 | put significant effort into it and is probably more familiar with it than |
62 | others. To find the maintainer of an applet, look at the top of the .c file |
63 | for a name following the word 'Copyright' or 'Written by' or 'Maintainer'. |
64 | |
65 | Before plunging ahead, it's a good idea to send a message to the mailing list |
66 | that says: "Hey, I was thinking about adding the 'transmogrify' feature to the |
67 | 'foo' applet. Would this be useful? Is anyone else working on it?" You might |
68 | want to CC the maintainer (if any) with your question. |
69 | |
70 | |
71 | |
72 | Areas Where You Can Help |
73 | ------------------------ |
74 | |
75 | Busybox can always use improvement! If you're looking for ways to help, there |
76 | are a variety of areas where you could help. |
77 | |
78 | |
79 | What Busybox Doesn't Need |
80 | ~~~~~~~~~~~~~~~~~~~~~~~~~ |
81 | |
82 | Before listing the areas where you _can_ help, it's worthwhile to mention the |
83 | areas where you shouldn't bother. While Busybox strives to be the "Swiss Army |
84 | Knife" of embedded Linux, there are some applets that will not be accepted: |
85 | |
86 | - Any filesystem manipulation tools: Busybox is filesystem independent and |
87 | we do not want to start adding mkfs/fsck tools for every (or any) |
88 | filesystem under the sun. (fsck_minix.c and mkfs_minix.c are living on |
89 | borrowed time.) There are far too many of these tools out there. Use |
90 | the upstream version. Not everything has to be part of Busybox. |
91 | |
92 | - Any partitioning tools: Partitioning a device is typically done once and |
93 | only once, and tools which do this generally do not need to reside on the |
94 | target device (esp a flash device). If you need a partitioning tool, grab |
95 | one (such as fdisk, sfdisk, or cfdisk from util-linux) and use that, but |
96 | don't try to merge it into busybox. These are nasty and complex and we |
97 | don't want to maintain them. |
98 | |
99 | - Any disk, device, or media-specific tools: Use the -utils or -tools package |
100 | that was designed for your device; don't try to shoehorn them into Busybox. |
101 | |
102 | - Any architecture specific tools: Busybox is (or should be) architecture |
103 | independent. Do not send us tools that cannot be used across multiple |
104 | platforms / arches. |
105 | |
106 | - Any daemons that are not essential to basic system operation. To date, only |
107 | syslogd and klogd meet this requirement. We do not need a web server, an |
108 | ftp daemon, a dhcp server, a mail transport agent or a dns resolver. If you |
109 | need one of those, you are welcome to ask the folks on the mailing list for |
110 | recommendations, but please don't bloat up Busybox with any of these. |
111 | |
112 | |
113 | Bug Reporting |
114 | ~~~~~~~~~~~~~ |
115 | |
116 | If you find bugs, please submit a detailed bug report to the busybox mailing |
117 | list at busybox@busybox.net. A well-written bug report should include a |
118 | transcript of a shell session that demonstrates the bad behavior and enables |
119 | anyone else to duplicate the bug on their own machine. The following is such |
120 | an example: |
121 | |
122 | To: busybox@busybox.net |
123 | From: diligent@testing.linux.org |
124 | Subject: /bin/date doesn't work |
125 | |
126 | Package: busybox |
127 | Version: 1.00 |
128 | |
129 | When I execute Busybox 'date' it produces unexpected results. |
130 | With GNU date I get the following output: |
131 | |
132 | $ date |
133 | Wed Mar 21 14:19:41 MST 2001 |
134 | |
135 | But when I use BusyBox date I get this instead: |
136 | |
137 | $ date |
138 | llegal instruction |
139 | |
140 | I am using Debian unstable, kernel version 2.4.19-rmk1 on an Netwinder, |
141 | and the latest uClibc from CVS. Thanks for the wonderful program! |
142 | |
143 | -Diligent |
144 | |
145 | Note the careful description and use of examples showing not only what BusyBox |
146 | does, but also a counter example showing what an equivalent GNU app does. Bug |
147 | reports lacking such detail may never be fixed... Thanks for understanding. |
148 | |
149 | |
150 | |
151 | Write Documentation |
152 | ~~~~~~~~~~~~~~~~~~~ |
153 | |
154 | Chances are, documentation in Busybox is either missing or needs improvement. |
155 | Either way, help is welcome. |
156 | |
157 | Work is being done to automatically generate documentation from sources, |
158 | especially from the usage.h file. If you want to correct the documentation, |
159 | please make changes to the pre-generation parts, rather than the generated |
160 | documentation. [More to come on this later...] |
161 | |
162 | It is preferred that modifications to documentation be submitted in patch |
163 | format (more on this below), but we're a little more lenient when it comes to |
164 | docs. You could, for example, just say "after the listing of the mount |
165 | options, the following example would be helpful..." |
166 | |
167 | |
168 | Consult Existing Sources |
169 | ~~~~~~~~~~~~~~~~~~~~~~~~ |
170 | |
171 | For a quick listing of "needs work" spots in the sources, cd into the Busybox |
172 | directory and run the following: |
173 | |
174 | for i in TODO FIXME XXX; do find -name '*.[ch]'|xargs grep $i; done |
175 | |
176 | This will show all of the trouble spots or 'questionable' code. Pick a spot, |
177 | any spot, these are all invitations for you to contribute. |
178 | |
179 | |
180 | Add a New Applet |
181 | ~~~~~~~~~~~~~~~~ |
182 | |
183 | If you want to add a new applet to Busybox, we'd love to see it. However, |
184 | before you write any code, please ask beforehand on the mailing list something |
185 | like "Do you think applet 'foo' would be useful in Busybox?" or "Would you |
186 | guys accept applet 'foo' into Busybox if I were to write it?" If the answer is |
187 | "no" by the folks on the mailing list, then you've saved yourself some time. |
188 | Conversely, you could get some positive responses from folks who might be |
189 | interested in helping you implement it, or can recommend the best approach. |
190 | Perhaps most importantly, this is your way of calling "dibs" on something and |
191 | avoiding duplication of effort. |
192 | |
193 | Also, before you write a line of code, please read the 'new-applet-HOWTO.txt' |
194 | file in the docs/ directory. |
195 | |
196 | |
197 | Janitorial Work |
198 | ~~~~~~~~~~~~~~~ |
199 | |
200 | These are dirty jobs, but somebody's gotta do 'em. |
201 | |
202 | - Converting applets to use getopt() for option processing. Type 'find -name |
203 | '*.c'|grep -L getopt' to get a listing of the applets that currently don't |
204 | use getopt. If a .c file processes no options, it should have a line that |
205 | reads: /* no options, no getopt */ somewhere in the file. |
206 | |
207 | - Replace any "naked" calls to malloc, calloc, realloc, str[n]dup, fopen with |
208 | the x* equivalents found in libbb/xfuncs.c. |
209 | |
210 | - Security audits: |
211 | http://www.securityfocus.com/popups/forums/secprog/intro.shtml |
212 | |
213 | - Synthetic code removal: http://www.perl.com/pub/2000/06/commify.html - This |
214 | is very Perl-specific, but the advice given in here applies equally well to |
215 | C. |
216 | |
217 | - C library function use audits: Verifying that functions are being used |
218 | properly (called with the right args), replacing unsafe library functions |
219 | with safer versions, making sure return codes are being checked, etc. |
220 | |
221 | - Where appropriate, replace preprocessor defined macros and values with |
222 | compile-time equivalents. |
223 | |
224 | - Style guide compliance. See: docs/style-guide.txt |
225 | |
226 | - Add testcases to tests/testcases. |
227 | |
228 | - Makefile improvements: |
229 | http://www.canb.auug.org.au/~millerp/rmch/recu-make-cons-harm.html |
230 | (I think the recursive problems are pretty much taken care of at this point, non?) |
231 | |
232 | - "Ten Commandments" compliance: (this is a "maybe", certainly not as |
233 | important as any of the previous items.) |
234 | http://www.lysator.liu.se/c/ten-commandments.html |
235 | |
236 | Other useful links: |
237 | |
238 | - the comp.lang.c FAQ: http://web.onetelnet.ch/~twolf/tw/c/index.html#Sources |
239 | |
240 | |
241 | |
242 | Submitting Patches To Busybox |
243 | ----------------------------- |
244 | |
245 | Here are some guidelines on how to submit a patch to Busybox. |
246 | |
247 | |
248 | Making A Patch |
249 | ~~~~~~~~~~~~~~ |
250 | |
251 | If you've got anonymous CVS access set up, making a patch is simple. Just make |
252 | sure you're in the busybox/ directory and type 'cvs diff -bwu > mychanges.patch'. |
253 | You can send the resulting .patch file to the mailing list with a description |
254 | of what it does. (But not before you test it! See the next section for some |
255 | guidelines.) It is preferred that patches be sent as attachments, but it is |
256 | not required. |
257 | |
258 | Also, feel free to help test other people's patches and reply to them with |
259 | comments. You can apply a patch by saving it into your busybox/ directory and |
260 | typing 'patch < mychanges.patch'. Then you can recompile, see if it runs, test |
261 | if it works as advertised, and post your findings to the mailing list. |
262 | |
263 | NOTE: Please do not include extraneous or irrelevant changes in your patches. |
264 | Please do not try to "bundle" two patches together into one. Make single, |
265 | discreet changes on a per-patch basis. Sometimes you need to make a patch that |
266 | touches code in many places, but these kind of patches are rare and should be |
267 | coordinated with a maintainer. |
268 | |
269 | |
270 | Testing Guidelines |
271 | ~~~~~~~~~~~~~~~~~~ |
272 | |
273 | It's considered good form to test your new feature before you submit a patch |
274 | to the mailing list, and especially before you commit a change to CVS. Here |
275 | are some guidelines on how to test your changes. |
276 | |
277 | - Always test Busybox applets against GNU counterparts and make sure the |
278 | behavior / output is identical between the two. |
279 | |
280 | - Try several different permutations and combinations of the features you're |
281 | adding (i.e., different combinations of command-line switches) and make sure |
282 | they all work; make sure one feature does not interfere with another. |
283 | |
284 | - Make sure you test compiling against the source both with the feature |
285 | turned on and turned off in Config.h and make sure Busybox compiles cleanly |
286 | both ways. |
287 | |
288 | - Run the multibuild.pl script in the tests directory and make sure |
289 | everything checks out OK. (Do this from within the busybox/ directory by |
290 | typing: 'tests/multibuild.pl'.) |
291 | |
292 | |
293 | Making Sure Your Patch Doesn't Get Lost |
294 | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
295 | |
296 | If you don't want your patch to be lost or forgotten, send it to the busybox |
297 | mailing list with a subject line something like this: |
298 | |
299 | [PATCH] - Adds "transmogrify" feature to "foo" |
300 | |
301 | In the body, you should have a pseudo-header that looks like the following: |
302 | |
303 | Package: busybox |
304 | Version: v1.01pre (or whatever the current version is) |
305 | Severity: wishlist |
306 | |
307 | The remainder of the body should read along these lines: |
308 | |
309 | This patch adds the "transmogrify" feature to the "foo" applet. I have |
310 | tested this on [arch] system(s) and it works. I have tested it against the |
311 | GNU counterparts and the outputs are identical. I have run the scripts in |
312 | the 'tests' directory and nothing breaks. |
313 | |
314 | |
315 | |
316 | Improving Your Chances of Patch Acceptance |
317 | ------------------------------------------ |
318 | |
319 | Even after you send a brilliant patch to the mailing list, sometimes it can go |
320 | unnoticed, un-replied-to, and sometimes (sigh) even lost. This is an |
321 | unfortunate fact of life, but there are steps you can take to help your patch |
322 | get noticed and convince a maintainer that it should be added: |
323 | |
324 | |
325 | Be Succinct |
326 | ~~~~~~~~~~~ |
327 | |
328 | A patch that includes small, isolated, obvious changes is more likely to be |
329 | accepted than a patch that touches code in lots of different places or makes |
330 | sweeping, dubious changes. |
331 | |
332 | |
333 | Back It Up |
334 | ~~~~~~~~~~ |
335 | |
336 | Hard facts on why your patch is better than the existing code will go a long |
337 | way toward convincing maintainers that your patch should be included. |
338 | Specifically, patches are more likely to be accepted if they are provably more |
339 | correct, smaller, faster, simpler, or more maintainable than the existing |
340 | code. |
341 | |
342 | Conversely, any patch that is supported with nothing more than "I think this |
343 | would be cool" or "this patch is good because I say it is and I've got a Phd |
344 | in Computer Science" will likely be ignored. |
345 | |
346 | |
347 | Follow The Style Guide |
348 | ~~~~~~~~~~~~~~~~~~~~~~ |
349 | |
350 | It's considered good form to abide by the established coding style used in a |
351 | project; Busybox is no exception. We have gone so far as to delineate the |
352 | "elements of Busybox style" in the file docs/style-guide.txt. Please follow |
353 | them. |
354 | |
355 | |
356 | Work With Someone Else |
357 | ~~~~~~~~~~~~~~~~~~~~~~ |
358 | |
359 | Working on a patch in isolation is less effective than working with someone |
360 | else for a variety of reasons. If another Busybox user is interested in what |
361 | you're doing, then it's two (or more) voices instead of one that can petition |
362 | for inclusion of the patch. You'll also have more people that can test your |
363 | changes, or even offer suggestions on better approaches you could take. |
364 | |
365 | Getting other folks interested follows as a natural course if you've received |
366 | responses from queries to applet maintainer or positive responses from folks |
367 | on the mailing list. |
368 | |
369 | We've made strident efforts to put a useful "collaboration" infrastructure in |
370 | place in the form of mailing lists, the bug tracking system, and CVS. Please |
371 | use these resources. |
372 | |
373 | |
374 | Send Patches to the Bug Tracking System |
375 | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
376 | |
377 | This was mentioned above in the "Making Sure Your Patch Doesn't Get Lost" |
378 | section, but it is worth mentioning again. A patch sent to the mailing list |
379 | might be unnoticed and forgotten. A patch sent to the bug tracking system will |
380 | be stored and closely connected to the bug it fixes. |
381 | |
382 | |
383 | Be Polite |
384 | ~~~~~~~~~ |
385 | |
386 | The old saying "You'll catch more flies with honey than you will with vinegar" |
387 | applies when submitting patches to the mailing list for approval. The way you |
388 | present your patch is sometimes just as important as the actual patch itself |
389 | (if not more so). Being rude to the maintainers is not an effective way to |
390 | convince them that your patch should be included; it will likely have the |
391 | opposite effect. |
392 | |
393 | |
394 | |
395 | Committing Changes to CVS |
396 | ------------------------- |
397 | |
398 | If you submit several patches that demonstrate that you are a skilled and wise |
399 | coder, you may be invited to become a committer, thus enabling you to commit |
400 | changes directly to CVS. This is nice because you don't have to wait for |
401 | someone else to commit your change for you, you can just do it yourself. |
402 | |
403 | But note that this is a privilege that comes with some responsibilities. You |
404 | should test your changes before you commit them. You should also talk to an |
405 | applet maintainer before you make any kind of sweeping changes to somebody |
406 | else's code. Big changes should still go to the mailing list first. Remember, |
407 | being wise, polite, and discreet is more important than being clever. |
408 | |
409 | |
410 | When To Commit |
411 | ~~~~~~~~~~~~~~ |
412 | |
413 | Generally, you should feel free to commit a change if: |
414 | |
415 | - Your changes are small and don't touch many files |
416 | - You are fixing a bug |
417 | - Somebody has told you that it's okay |
418 | - It's obviously the Right Thing |
419 | |
420 | The more of the above are true, the better it is to just commit a change |
421 | directly to CVS. |
422 | |
423 | |
424 | When Not To Commit |
425 | ~~~~~~~~~~~~~~~~~~ |
426 | |
427 | Even if you have commit rights, you should probably still post a patch to the |
428 | mailing list if: |
429 | |
430 | - Your changes are broad and touch many different files |
431 | - You are adding a feature |
432 | - Your changes are speculative or experimental (i.e., trying a new algorithm) |
433 | - You are not the maintainer and your changes make the maintainer cringe |
434 | |
435 | The more of the above are true, the better it is to post a patch to the |
436 | mailing list instead of committing. |
437 | |
438 | |
439 | |
440 | Final Words |
441 | ----------- |
442 | |
443 | If all of this seems complicated, don't panic, it's really not that tough. If |
444 | you're having difficulty following some of the steps outlined in this |
445 | document don't worry, the folks on the Busybox mailing list are a fairly |
446 | good-natured bunch and will work with you to help get your patches into shape |
447 | or help you make contributions. |
448 | |
449 |