450 lines
16 KiB
Plaintext
Executable File
450 lines
16 KiB
Plaintext
Executable File
Contributing To Busybox
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=======================
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This document describes what you need to do to contribute to Busybox, where
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you can help, guidelines on testing, and how to submit a well-formed patch
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that is more likely to be accepted.
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The Busybox home page is at: http://busybox.net/
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Pre-Contribution Checklist
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--------------------------
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So you want to contribute to Busybox, eh? Great, wonderful, glad you want to
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help. However, before you dive in, headlong and hotfoot, there are some things
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you need to do:
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Checkout the Latest Code from CVS
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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This is a necessary first step. Please do not try to work with the last
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released version, as there is a good chance that somebody has already fixed
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the bug you found. Somebody might have even added the feature you had in mind.
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Don't make your work obsolete before you start!
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For information on how to check out Busybox from CVS, please look at the
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following links:
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http://busybox.net/cvs_anon.html
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http://busybox.net/cvs_howto.html
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Read the Mailing List
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~~~~~~~~~~~~~~~~~~~~~
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No one is required to read the entire archives of the mailing list, but you
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should at least read up on what people have been talking about lately. If
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you've recently discovered a problem, chances are somebody else has too. If
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you're the first to discover a problem, post a message and let the rest of us
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know.
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Archives can be found here:
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http://busybox.net/lists/busybox/
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If you have a serious interest in Busybox, i.e., you are using it day-to-day or
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as part of an embedded project, it would be a good idea to join the mailing
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list.
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A web-based sign-up form can be found here:
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http://busybox.net/mailman/listinfo/busybox
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Coordinate with the Applet Maintainer
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Some (not all) of the applets in Busybox are "owned" by a maintainer who has
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put significant effort into it and is probably more familiar with it than
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others. To find the maintainer of an applet, look at the top of the .c file
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for a name following the word 'Copyright' or 'Written by' or 'Maintainer'.
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Before plunging ahead, it's a good idea to send a message to the mailing list
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that says: "Hey, I was thinking about adding the 'transmogrify' feature to the
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'foo' applet. Would this be useful? Is anyone else working on it?" You might
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want to CC the maintainer (if any) with your question.
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Areas Where You Can Help
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------------------------
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Busybox can always use improvement! If you're looking for ways to help, there
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are a variety of areas where you could help.
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What Busybox Doesn't Need
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~~~~~~~~~~~~~~~~~~~~~~~~~
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Before listing the areas where you _can_ help, it's worthwhile to mention the
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areas where you shouldn't bother. While Busybox strives to be the "Swiss Army
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Knife" of embedded Linux, there are some applets that will not be accepted:
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- Any filesystem manipulation tools: Busybox is filesystem independent and
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we do not want to start adding mkfs/fsck tools for every (or any)
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filesystem under the sun. (fsck_minix.c and mkfs_minix.c are living on
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borrowed time.) There are far too many of these tools out there. Use
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the upstream version. Not everything has to be part of Busybox.
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- Any partitioning tools: Partitioning a device is typically done once and
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only once, and tools which do this generally do not need to reside on the
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target device (esp a flash device). If you need a partitioning tool, grab
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one (such as fdisk, sfdisk, or cfdisk from util-linux) and use that, but
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don't try to merge it into busybox. These are nasty and complex and we
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don't want to maintain them.
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- Any disk, device, or media-specific tools: Use the -utils or -tools package
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that was designed for your device; don't try to shoehorn them into Busybox.
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- Any architecture specific tools: Busybox is (or should be) architecture
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independent. Do not send us tools that cannot be used across multiple
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platforms / arches.
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- Any daemons that are not essential to basic system operation. To date, only
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syslogd and klogd meet this requirement. We do not need a web server, an
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ftp daemon, a dhcp server, a mail transport agent or a dns resolver. If you
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need one of those, you are welcome to ask the folks on the mailing list for
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recommendations, but please don't bloat up Busybox with any of these.
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Bug Reporting
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~~~~~~~~~~~~~
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If you find bugs, please submit a detailed bug report to the busybox mailing
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list at busybox@busybox.net. A well-written bug report should include a
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transcript of a shell session that demonstrates the bad behavior and enables
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anyone else to duplicate the bug on their own machine. The following is such
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an example:
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To: busybox@busybox.net
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From: diligent@testing.linux.org
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Subject: /bin/date doesn't work
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Package: busybox
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Version: 1.00
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When I execute Busybox 'date' it produces unexpected results.
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With GNU date I get the following output:
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$ date
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Wed Mar 21 14:19:41 MST 2001
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But when I use BusyBox date I get this instead:
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$ date
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llegal instruction
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I am using Debian unstable, kernel version 2.4.19-rmk1 on an Netwinder,
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and the latest uClibc from CVS. Thanks for the wonderful program!
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-Diligent
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Note the careful description and use of examples showing not only what BusyBox
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does, but also a counter example showing what an equivalent GNU app does. Bug
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reports lacking such detail may never be fixed... Thanks for understanding.
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Write Documentation
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~~~~~~~~~~~~~~~~~~~
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Chances are, documentation in Busybox is either missing or needs improvement.
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Either way, help is welcome.
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Work is being done to automatically generate documentation from sources,
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especially from the usage.h file. If you want to correct the documentation,
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please make changes to the pre-generation parts, rather than the generated
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documentation. [More to come on this later...]
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It is preferred that modifications to documentation be submitted in patch
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format (more on this below), but we're a little more lenient when it comes to
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docs. You could, for example, just say "after the listing of the mount
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options, the following example would be helpful..."
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Consult Existing Sources
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~~~~~~~~~~~~~~~~~~~~~~~~
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For a quick listing of "needs work" spots in the sources, cd into the Busybox
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directory and run the following:
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for i in TODO FIXME XXX; do find -name '*.[ch]'|xargs grep $i; done
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This will show all of the trouble spots or 'questionable' code. Pick a spot,
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any spot, these are all invitations for you to contribute.
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Add a New Applet
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~~~~~~~~~~~~~~~~
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If you want to add a new applet to Busybox, we'd love to see it. However,
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before you write any code, please ask beforehand on the mailing list something
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like "Do you think applet 'foo' would be useful in Busybox?" or "Would you
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guys accept applet 'foo' into Busybox if I were to write it?" If the answer is
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"no" by the folks on the mailing list, then you've saved yourself some time.
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Conversely, you could get some positive responses from folks who might be
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interested in helping you implement it, or can recommend the best approach.
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Perhaps most importantly, this is your way of calling "dibs" on something and
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avoiding duplication of effort.
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Also, before you write a line of code, please read the 'new-applet-HOWTO.txt'
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file in the docs/ directory.
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Janitorial Work
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~~~~~~~~~~~~~~~
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These are dirty jobs, but somebody's gotta do 'em.
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- Converting applets to use getopt() for option processing. Type 'find -name
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'*.c'|grep -L getopt' to get a listing of the applets that currently don't
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use getopt. If a .c file processes no options, it should have a line that
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reads: /* no options, no getopt */ somewhere in the file.
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- Replace any "naked" calls to malloc, calloc, realloc, str[n]dup, fopen with
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the x* equivalents found in libbb/xfuncs.c.
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- Security audits:
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http://www.securityfocus.com/popups/forums/secprog/intro.shtml
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- Synthetic code removal: http://www.perl.com/pub/2000/06/commify.html - This
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is very Perl-specific, but the advice given in here applies equally well to
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C.
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- C library function use audits: Verifying that functions are being used
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properly (called with the right args), replacing unsafe library functions
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with safer versions, making sure return codes are being checked, etc.
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- Where appropriate, replace preprocessor defined macros and values with
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compile-time equivalents.
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- Style guide compliance. See: docs/style-guide.txt
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- Add testcases to tests/testcases.
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- Makefile improvements:
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http://www.canb.auug.org.au/~millerp/rmch/recu-make-cons-harm.html
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(I think the recursive problems are pretty much taken care of at this point, non?)
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- "Ten Commandments" compliance: (this is a "maybe", certainly not as
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important as any of the previous items.)
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http://www.lysator.liu.se/c/ten-commandments.html
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Other useful links:
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- the comp.lang.c FAQ: http://web.onetelnet.ch/~twolf/tw/c/index.html#Sources
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Submitting Patches To Busybox
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-----------------------------
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Here are some guidelines on how to submit a patch to Busybox.
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Making A Patch
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~~~~~~~~~~~~~~
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If you've got anonymous CVS access set up, making a patch is simple. Just make
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sure you're in the busybox/ directory and type 'cvs diff -bwu > mychanges.patch'.
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You can send the resulting .patch file to the mailing list with a description
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of what it does. (But not before you test it! See the next section for some
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guidelines.) It is preferred that patches be sent as attachments, but it is
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not required.
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Also, feel free to help test other people's patches and reply to them with
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comments. You can apply a patch by saving it into your busybox/ directory and
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typing 'patch < mychanges.patch'. Then you can recompile, see if it runs, test
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if it works as advertised, and post your findings to the mailing list.
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NOTE: Please do not include extraneous or irrelevant changes in your patches.
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Please do not try to "bundle" two patches together into one. Make single,
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discreet changes on a per-patch basis. Sometimes you need to make a patch that
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touches code in many places, but these kind of patches are rare and should be
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coordinated with a maintainer.
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Testing Guidelines
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~~~~~~~~~~~~~~~~~~
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It's considered good form to test your new feature before you submit a patch
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to the mailing list, and especially before you commit a change to CVS. Here
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are some guidelines on how to test your changes.
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- Always test Busybox applets against GNU counterparts and make sure the
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behavior / output is identical between the two.
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- Try several different permutations and combinations of the features you're
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adding (i.e., different combinations of command-line switches) and make sure
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they all work; make sure one feature does not interfere with another.
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- Make sure you test compiling against the source both with the feature
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turned on and turned off in Config.h and make sure Busybox compiles cleanly
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both ways.
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- Run the multibuild.pl script in the tests directory and make sure
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everything checks out OK. (Do this from within the busybox/ directory by
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typing: 'tests/multibuild.pl'.)
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Making Sure Your Patch Doesn't Get Lost
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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If you don't want your patch to be lost or forgotten, send it to the busybox
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mailing list with a subject line something like this:
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[PATCH] - Adds "transmogrify" feature to "foo"
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In the body, you should have a pseudo-header that looks like the following:
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Package: busybox
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Version: v1.01pre (or whatever the current version is)
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Severity: wishlist
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The remainder of the body should read along these lines:
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This patch adds the "transmogrify" feature to the "foo" applet. I have
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tested this on [arch] system(s) and it works. I have tested it against the
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GNU counterparts and the outputs are identical. I have run the scripts in
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the 'tests' directory and nothing breaks.
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Improving Your Chances of Patch Acceptance
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------------------------------------------
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Even after you send a brilliant patch to the mailing list, sometimes it can go
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unnoticed, un-replied-to, and sometimes (sigh) even lost. This is an
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unfortunate fact of life, but there are steps you can take to help your patch
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get noticed and convince a maintainer that it should be added:
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Be Succinct
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~~~~~~~~~~~
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A patch that includes small, isolated, obvious changes is more likely to be
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accepted than a patch that touches code in lots of different places or makes
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sweeping, dubious changes.
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Back It Up
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~~~~~~~~~~
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Hard facts on why your patch is better than the existing code will go a long
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way toward convincing maintainers that your patch should be included.
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Specifically, patches are more likely to be accepted if they are provably more
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correct, smaller, faster, simpler, or more maintainable than the existing
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code.
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Conversely, any patch that is supported with nothing more than "I think this
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would be cool" or "this patch is good because I say it is and I've got a Phd
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in Computer Science" will likely be ignored.
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Follow The Style Guide
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~~~~~~~~~~~~~~~~~~~~~~
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It's considered good form to abide by the established coding style used in a
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project; Busybox is no exception. We have gone so far as to delineate the
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"elements of Busybox style" in the file docs/style-guide.txt. Please follow
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them.
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Work With Someone Else
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~~~~~~~~~~~~~~~~~~~~~~
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Working on a patch in isolation is less effective than working with someone
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else for a variety of reasons. If another Busybox user is interested in what
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you're doing, then it's two (or more) voices instead of one that can petition
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for inclusion of the patch. You'll also have more people that can test your
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changes, or even offer suggestions on better approaches you could take.
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Getting other folks interested follows as a natural course if you've received
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responses from queries to applet maintainer or positive responses from folks
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on the mailing list.
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We've made strident efforts to put a useful "collaboration" infrastructure in
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place in the form of mailing lists, the bug tracking system, and CVS. Please
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use these resources.
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Send Patches to the Bug Tracking System
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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This was mentioned above in the "Making Sure Your Patch Doesn't Get Lost"
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section, but it is worth mentioning again. A patch sent to the mailing list
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might be unnoticed and forgotten. A patch sent to the bug tracking system will
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be stored and closely connected to the bug it fixes.
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Be Polite
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~~~~~~~~~
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The old saying "You'll catch more flies with honey than you will with vinegar"
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applies when submitting patches to the mailing list for approval. The way you
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present your patch is sometimes just as important as the actual patch itself
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(if not more so). Being rude to the maintainers is not an effective way to
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convince them that your patch should be included; it will likely have the
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opposite effect.
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Committing Changes to CVS
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-------------------------
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If you submit several patches that demonstrate that you are a skilled and wise
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coder, you may be invited to become a committer, thus enabling you to commit
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changes directly to CVS. This is nice because you don't have to wait for
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someone else to commit your change for you, you can just do it yourself.
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But note that this is a priviledge that comes with some responsibilities. You
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should test your changes before you commit them. You should also talk to an
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applet maintainer before you make any kind of sweeping changes to somebody
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else's code. Big changes should still go to the mailing list first. Remember,
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being wise, polite, and discreet is more important than being clever.
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When To Commit
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~~~~~~~~~~~~~~
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Generally, you should feel free to commit a change if:
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- Your changes are small and don't touch many files
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- You are fixing a bug
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- Somebody has told you that it's okay
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- It's obviously the Right Thing
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The more of the above are true, the better it is to just commit a change
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directly to CVS.
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When Not To Commit
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~~~~~~~~~~~~~~~~~~
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Even if you have commit rights, you should probably still post a patch to the
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mailing list if:
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- Your changes are broad and touch many different files
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- You are adding a feature
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- Your changes are speculative or experimental (i.e., trying a new algorithm)
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- You are not the maintainer and your changes make the maintainer cringe
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The more of the above are true, the better it is to post a patch to the
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mailing list instead of committing.
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Final Words
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-----------
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If all of this seems complicated, don't panic, it's really not that tough. If
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you're having difficulty following some of the steps outlined in this
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document don't worry, the folks on the Busybox mailing list are a fairly
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good-natured bunch and will work with you to help get your patches into shape
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or help you make contributions.
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