Merge pull request #842 from qlyoung/update-style-guide

Update COMMUNITY.md
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@ -1,4 +1,7 @@
# Developing for PROJECT (DRAFT)
Developing for FRRouting
=========================
## Table of Contents
[TOC]
@ -14,55 +17,57 @@ it's the document that needs to be updated, not reality.
## Git Structure
The master Git for PROJECT resides on Github at
[https://github.com/PROJECT/XXX](https://github.com/PROJECT/XXX)
The master Git for FRRouting resides on Github at
[https://github.com/frrouting/frr](https://github.com/FRRouting/frr)
![git branches continually merging to the left from 3 lanes; float-right](doc/git_branches.svg
"git branch mechanics")
There is one main branch for development and a release branch for each
major release.
There is one main branch for development and a release branch for each major
release.
New contributions are done against the head of the master branch. The CI
systems will pick up the Github Pull Requests or the new patch from
Patchwork, run some basic build and functional tests.
systems will pick up the Github Pull Requests or the new patch from Patchwork,
run some basic build and functional tests.
For each major release (1.0, 1.1 etc) a new release branch is created based
on the master.
For each major release (1.0, 1.1 etc) a new release branch is created based on
the master.
There was an attempt to use a "develop" branch automatically maintained by
the CI system. This is not currently in active use, though the system is
operational. If the "develop" branch is in active use and this paragraph
is still here, this document obviously wasn't updated.
There was an attempt to use a "develop" branch automatically maintained by the
CI system. This is not currently in active use, though the system is
operational. If the "develop" branch is in active use and this paragraph is
still here, this document obviously wasn't updated.
## Programming language, Tools and Libraries
The core of PROJECT is written in C (gcc or clang supported). A few
non-essential scripts are implemented in Perl and Python. PROJECT requires
the following tools to build distribution packages: automake, autoconf,
texinfo, libtool and gawk and various libraries (i.e. libpam and libjson-c).
The core of FRRouting is written in C (gcc or clang supported) and makes use of
GNU compiler extensions. A few non-essential scripts are implemented in Perl
and Python. FRRouting requires the following tools to build distribution
packages: automake, autoconf, texinfo, libtool and gawk and various libraries
(i.e. libpam and libjson-c).
If your contribution requires a new library or other tool, then please
highlight this in your description of the change. Also make sure its
supported by all PROJECT platform OSes or provide a way to build without the
library (potentially without the new feature) on the other platforms.
highlight this in your description of the change. Also make sure its supported
by all FRRouting platform OSes or provide a way to build without the library
(potentially without the new feature) on the other platforms.
Documentation should be written in Tex (.texi) or Markdown (.md) format with
preference on Markdown.
Documentation should be written in Tex (.texi) or Markdown (.md) format with a
preference for Markdown.
## Before Submitting your changes
## Mailing lists
Italicized lists are private.
| Topic | List |
|--------------------------------|------------------------------|
| Development | dev@lists.frrouting.org |
| Users & Operators | frog@lists.frrouting.org |
| Announcements | announce@lists.frrouting.org |
| _Security_ | security@lists.frrouting.org |
| _Technical Steering Committee_ | tsc@lists.frrouting.org |
* Format code (see [Code Styling requirements](#code-styling-requirements))
* Verify and acknowledge license (see [License for contributions](#license-for-contributions))
* Test building with various configurations:
* `buildtest.sh`
* Verify building source distribution:
* `make dist` (and try rebuilding from the resulting tar file)
* Run DejaGNU unit tests:
* `make test`
* Document Regression Runs and plans for continued maintenance of the feature
### Changelog
@ -75,16 +80,45 @@ for the release notes.
## Submitting Patches and Enhancements
### Pre-submission Checklist
* Format code (see [Coding style requirements](#coding-style-requirements))
* Verify and acknowledge license (see [License for contributions](#license-for-contributions))
* Ensure you have properly signed off (see [Signing Off](#signing-off))
* Test building with various configurations:
* `buildtest.sh`
* Verify building source distribution:
* `make dist` (and try rebuilding from the resulting tar file)
* Run unit tests:
* `make test`
* Document Regression Runs and plans for continued maintenance of the feature
### License for contributions
PROJECT is under a “GPLv2 or later” license. Any code submitted must be
FRRouting is under a “GPLv2 or later” license. Any code submitted must be
released under the same license (preferred) or any license which allows
redistribution under this GPLv2 license (eg MIT License).
### Signed-off required
### Signing Off
Submissions to PROJECT require a “Signed-off” in the patch or git commit.
We follow the same standard as the Linux Kernel Development.
Code submitted to FRRouting must be signed off. We have the same requirements
for using the signed-off-by process as the Linux kernel. In short, you must
include a signed-off-by tag in every patch.
`Signed-off-by:` this is a developer's certification that he or she has the
right to submit the patch for inclusion into the project. It is an agreement to
the Developer's Certificate of Origin (below). Code without a proper signoff
can not and will not be merged.
If you are unfamiliar with this process, you should read the [official policy
at kernel.org](http://www.kernel.org/doc/Documentation/SubmittingPatches) and
you might find this article about [participating in the Linux community on the
Linux Foundation
website](http://www.linuxfoundation.org/content/how-participate-linux-community-0)
to be a helpful resource.
In short, when you sign off on a commit, you assert your agreement to all of
the following:
> Developer's Certificate of Origin 1.1
>
@ -112,79 +146,46 @@ We follow the same standard as the Linux Kernel Development.
> maintained indefinitely and may be redistributed consistent with
> this project or the open source license(s) involved.
#### Using this Process
We have the same requirements for using the signed-off-by process as the Linux
kernel. In short, you need to include a signed-off-by tag in every patch:
* `Signed-off-by:` this is a developer's certification that he or she has the
right to submit the patch for inclusion into the project. It is an agreement to
the Developer's Certificate of Origin (above). Code without a proper signoff
cannot be merged into the mainline.
Please make sure to have a `Signed-off-by:` in each commit/patch or the patches
will be rejected until this is added.
If you are unfamiliar with this process, you should read the [official policy
at kernel.org](http://www.kernel.org/doc/Documentation/SubmittingPatches) and
you might find this article about [participating in the Linux community on the
Linux Foundation
website](http://www.linuxfoundation.org/content/how-participate-linux-community-0)
to be a helpful resource.
### Code submission - What do I submit my changes against?
### What do I submit my changes against?
We've documented where we would like to have the different fixes applied at
https://github.com/FRRouting/frr/wiki/Where-Do-I-create-a-Pull-Request-against%3F
If you are unsure where your submission goes, look at that document or ask
the question of a maintainer.
If you are unsure where your submission goes, look at that document or ask a
project maintainer.
### Code submission - Github Pull Request (Strongly Preferred)
### Github pull requests
Preferred submission of code is by using a Github Pull Request against the
Develop branch. Code submitted by Pull Request will have an email generated to
the PROJECT-devel mailing list for review and the submission will be
automatically tested by one or more CI systems. Only after this test succeeds
(and the submission is based on the head of the develop branch), then it will
be automatically merged into the develop branch. In case of failed tests, it is
up to the submitter to either amend the request with further commits or close,
fix and create a new pull request.
The preferred method of submitting changes is a Github pull request. Code
submitted by pull request will be automatically tested by one or more CI
systems. Once the automated tests succeed, other developers will review your
code for quality and correctness. After any concerns are resolved, your code
will be merged into the branch it was submitted against.
Further (manual) code review and discussion happens after the merge into the
develop branch.
### Patch submission via mailing list
### Code submission - Mailing Patch to PROJECT-Devel list
As an alternative submission, a patch can be mailed to the PROJECT-Devel
mailing list. Preferred way to send the patch is using git send-mail. Patches
received on the mailing list will be picked up by Patchwork and tested against
the latest develop branch. After a further ACK by someone on the mailing list,
the patch is then merged into the develop branch.
Further (manual) code review and discussion happens after the merge into the
develop branch.
#### Sending patch to mailing list
As an alternative submission method, a patch can be mailed to the development
mailing list. Patches received on the mailing list will be picked up by
Patchwork and tested against the latest development branch.
The recommended way to send the patch (or series of NN patches) to the list is
by using git send-email as follows (assuming they are the most recent NN
by using `git send-email` as follows (assuming they are the N most recent
commit(s) in your git history:
```
git send-email -NN --annotate --to=XXX-Devel@XXX.org
git send-email -NN --annotate --to=dev@lists.frrouting.org
```
If your commits do not already contain a `Signed-off-by` line, then use the
following version to add it (after making sure to be able to agree to the
Developer Certificate of Origin as outlined above):
following command to add it (after making sure you agree to the Developer
Certificate of Origin as outlined above):
```
git send-email -NN --annotate --signoff --to=XXX-Devel@XXX.org
git send-email -NN --annotate --signoff --to=dev@lists.frrouting.org
```
Submitting multi-commit patches as a Github Pull Request is strongly encouraged
and will allow your changes to merge faster
Submitting multi-commit patches as a Github pull request is **strongly
encouraged** and increases the probability of your patch getting reviewed and
merged in a timely manner.
## After submitting your changes
@ -194,35 +195,34 @@ and will allow your changes to merge faster
less than 2 hrs of the submission. If you dont get the email, then check
status on the github pull request (if submitted by pull request) or on
Patchwork at
[https://patchwork.PROJECT.org](https://patchwork.PROJECT.org) (if
[https://patchwork.frrouting.org](https://patchwork.frrouting.org) (if
submitted as patch to mailing list).
* Please notify PROJECT-Devel mailing list if you think something doesnt
work
* Please notify the development mailing list if you think something doesnt
work.
* If the tests failed:
* In general, expect the community to ignore the submission until the tests
pass.
* It is up to you to fix and resubmit.
* This includes fixing existing dejagnu (“make test”) tests if your
* This includes fixing existing unit (“make test”) tests if your
changes broke or changed them.
* It also includes fixing distribution packages for the failing
platforms (ie if new libraries are required)
* Feel free to ask for help on PROJECT-Devel list
platforms (ie if new libraries are required).
* Feel free to ask for help on the development list.
* Go back to the submission process and repeat until the tests pass.
* If the tests pass:
* If the changes are done as a pull request, then they should be
automatically merged to the develop branch.
* Changes sent to mailing list require a manual ACK to be merged and should
be merged within 2 weeks. If you dont see the merge or any
reason/discussion on PROJECT-Devel, then please ask.
* Wait for reviewers. Someone will review your code or be assigned to
review your code.
* Respond to any comments or concerns the reviewer has.
* After all comments and concerns are addressed, expect your patch to be
merged.
* Watch out for questions on the mailing list. At this time there will be a
manual code review and further (longer) tests by various community members.
* Your submission is done once it is merged to the master branch. (which should
happen every few weeks from the develop branch)
* Your submission is done once it is merged to the master branch.
## Code Styling requirements
## Developer's Guidelines
### File header required for new files added
### Source file header
New files need to have a Copyright header (see [License for
contributions](#license-for-contributions) above) added to the file. Preferred
@ -251,7 +251,7 @@ form of the header is as follows:
#include <zebra.h>
```
### Adding Copyright claims to already existing file
### Adding copyright claims to existing files
When adding copyright claims for modifications to an existing file, please
preface the claim with "Portions: " on a line before it and indent the
@ -264,95 +264,147 @@ Portions:
Copyright (C) 2016 Your name [optional brief change description]
```
### Code styling / format
### Code formatting
Coding style standards in FRR vary depending on location. Pre-existing
code uses GNU coding standards. New code may use Linux kernel coding style.
FRR uses Linux kernel style except where noted below. Code which does not
comply with these style guidelines will not be accepted.
GNU coding style apply to the following parts:
* lib/
* zebra/
* bgpd/
* ospfd/
* ospf6d/
* isisd/
* ripd/
* ripngd/
* vtysh/
Linux kernel coding style applies to:
* nhrpd/
* watchfrr/
* pimd/
* lib/{checksum,hook,imsg-buffer,imsg,libfrr,md5,module,monotime,queue}.[ch]
BSD coding style applies to:
* ldpd/
To assist with compliance, in the project root there is a .clang-format
configuration file which can be used with the `clang-format` tool from the LLVM
project. In the `tools/` directory there is a Python script named `indent.py`
that wraps clang-format and handles some edge cases specific to FRR. If you are
submitting a new file, it is recommended to run that script over the new file
after ensuring that the latest stable release of `clang-format` is in your
PATH.
**Whitespace changes in untouched parts of the code are not acceptable in
patches that change actual code.** To change/fix formatting issues, please
create a separate patch that only does formatting changes and nothing else.
It is acceptable to rewrap entire files to Linux kernel style, but this
**MUST** come as a separate patch that does nothing other than this
reformatting.
#### Style documentation
Kernel and BSD styles are documented externally:
* [https://www.kernel.org/doc/html/latest/process/coding-style.html](https://www.kernel.org/doc/html/latest/process/coding-style.html)
* [http://man.openbsd.org/style](http://man.openbsd.org/style)
#### GNU style
For GNU coding style, Indentation follows the result of invoking GNU indent:
For GNU coding style, use `indent` with the following invocation:
```
indent -nut -nfc1 file_for_submission.c
```
Originally, tabs were used instead of spaces, with tabs are every 8 columns.
However, tab interoperability issues mean space characters are now preferred for
new changes. We generally only clean up whitespace when code is unmaintainable
due to whitespace issues, to minimise merging conflicts.
#### Exceptions
FRR project code comes from a variety of sources, so there are some stylistic
exceptions in place. They are organized here by branch.
**For `master`:**
BSD coding style applies to:
* `ldpd/`
`babeld` uses, approximately, the following style:
* K&R style braces
* Indents are 4 spaces
* Function return types are on their own line
#### Linux kernel & BSD style
**For `stable/3.0` and `stable/2.0`:**
These styles are documented externally:
GNU coding style apply to the following parts:
* [https://www.kernel.org/doc/Documentation/CodingStyle](https://www.kernel.org/doc/Documentation/CodingStyle).
* [http://man.openbsd.org/style](http://man.openbsd.org/style)
* `lib/`
* `zebra/`
* `bgpd/`
* `ospfd/`
* `ospf6d/`
* `isisd/`
* `ripd/`
* `ripngd/`
* `vtysh/`
They are relatively similar but differ in details.
BSD coding style applies to:
pimd deviates from Linux kernel style in using 2 spaces for indentation, with
Tabs replacing 8 spaces, as well as adding a line break between `}` and `else`.
It is acceptable to convert indentation in pimd/ to Linux kernel style, but
please convert an entire file at a time. (Rationale: apart from 2-space
indentation, the styles are sufficiently close to not upset when mixed.)
Unlike GNU style, these styles use tabs, not spaces.
* `ldpd/`
### Compile-Time conditional code
### Documentation
Many users access PROJECT via binary packages from 3rd party sources;
compile-time code puts inclusion/exclusion in the hands of the package
maintainer. Please think very carefully before making code conditional at
compile time, as it increases regression testing, maintenance burdens, and user
confusion. In particular, please avoid gratuitous --enable-… switches to the
configure script - typically code should be good enough to be in PROJECT, or it
shouldnt be there at all.
FRRouting is a large and complex software project developed by many different
people over a long period of time. Without adequate documentation, it can be
exceedingly difficult to understand code segments, APIs and other interfaces.
In the interest of keeping the project healthy and maintainable, you should
make every effort to document your code so that other people can understand
what it does without needing to closely read the code itself.
Some specific guidelines that contributors should follow are:
* Functions exposed in header files should have descriptive comments above
their signatures in the header file. At a minimum, a function comment should
contain information about the return value, parameters, and a general summary
of the function's purpose. Documentation on parameter values can be omitted
if it is (very) obvious what they are used for.
Function comments must follow the style for multiline comments laid out in
the kernel style guide.
Example:
```
/*
* Determines whether or not a string is cool.
*
* @param text - the string to check for coolness
* @param is_clccfc - whether capslock is cruise control for cool
* @return 7 if the text is cool, 0 otherwise
*/
int check_coolness(const char *text, bool is_clccfc);
```
The Javadoc-style annotations are not required, but you should still strive to
make it equally clear what parameters and return values are used for.
* Static functions should have descriptive comments in the same form as above
if what they do is not immediately obvious. Use good engineering judgement
when deciding whether a comment is necessary. If you are unsure, document
your code.
* Global variables, static or not, should have a comment describing their use.
* **For new code in `lib/`, these guidelines are hard requirements.**
If you are contributing code that adds significant user-visible functionality
or introduces a new API, please document it in `doc/`. Markdown and LaTeX are
acceptable formats, although Markdown is currently preferred for new
documentation. This may change in the near future.
Finally, if you come across some code that is undocumented and feel like going
above and beyond, document it! We absolutely appreciate and accept patches that
document previously undocumented code.
### Compile-time conditional code
Many users access FRR via binary packages from 3rd party sources; compile-time
code puts inclusion/exclusion in the hands of the package maintainer. Please
think very carefully before making code conditional at compile time, as it
increases regression testing, maintenance burdens, and user confusion. In
particular, please avoid gratuitous `--enable-…` switches to the configure
script - in general, code should be of high quality and in working condition,
or it shouldnt be in FRR at all.
When code must be compile-time conditional, try have the compiler make it
conditional rather than the C pre-processor - so that it will still be checked
by the compiler, even if disabled. I.e. this:
conditional rather than the C pre-processor so that it will still be checked by
the compiler, even if disabled. For example,
```
if (SOME_SYMBOL)
frobnicate();
```
rather than
is preferred to
```
#ifdef SOME_SYMBOL
@ -363,53 +415,55 @@ frobnicate ();
Note that the former approach requires ensuring that `SOME_SYMBOL` will be
defined (watch your `AC_DEFINE`s).
### Debug-Guards in code
### Debug-guards in code
Debugs are an important methodology to allow developers to fix issues
found in the code after it has been released. The caveat here is
that the developer must remember that people will be using the code
at scale and in ways that can be unexpected for the original implementor.
As such debugs MUST be guarded in such a way that they can be turned off.
This PROJECT has the ability to turn on/off debugs from the CLI and it is
expected that the developer will use this convention to allow control
of their debugs.
Debugging statements are an important methodology to allow developers to fix
issues found in the code after it has been released. The caveat here is that
the developer must remember that people will be using the code at scale and in
ways that can be unexpected for the original implementor. As such debugs
**MUST** be guarded in such a way that they can be turned off. FRR has the
ability to turn on/off debugs from the CLI and it is expected that the
developer will use this convention to allow control of their debugs.
### CLI-Changes
### CLI changes
CLI's are a complicated ugly beast. Additions or changes to the CLI
should use a DEFUN to encapsulate one setting as much as is possible.
Additionally as new DEFUN's are added to the system, documentation
should be provided for the new commands.
CLI's are a complicated ugly beast. Additions or changes to the CLI should use
a DEFUN to encapsulate one setting as much as is possible. Additionally as new
DEFUN's are added to the system, documentation should be provided for the new
commands.
### Backwards Compatibility
As a general principle, changes to CLI and code in the lib/ directory
should be made in a backwards compatible fashion. This means that
changes that are purely stylistic in nature should be avoided, e.g.,
renaming an existing macro or library function name without any
functional change. When adding new parameters to common functions, it is
also good to consider if this too should be done in a backward
compatible fashion, e.g., by preserving the old form in addition to
As a general principle, changes to CLI and code in the lib/ directory should be
made in a backwards compatible fashion. This means that changes that are purely
stylistic in nature should be avoided, e.g., renaming an existing macro or
library function name without any functional change. When adding new parameters
to common functions, it is also good to consider if this too should be done in
a backward compatible fashion, e.g., by preserving the old form in addition to
adding the new form.
This is not to say that minor or even major functional changes to CLI
and common code should be avoided, but rather that the benefit gained
from a change should be weighed against the added cost/complexity to
existing code. Also, that when making such changes, it is good to
preserve compatibility when possible to do so without introducing
maintenance overhead/cost. It is also important to keep in mind,
existing code includes code that may reside in private repositories (and
is yet to be submitted) or code that has yet to be migrated from Quagga
to FRR.
This is not to say that minor or even major functional changes to CLI and
common code should be avoided, but rather that the benefit gained from a change
should be weighed against the added cost/complexity to existing code. Also,
that when making such changes, it is good to preserve compatibility when
possible to do so without introducing maintenance overhead/cost. It is also
important to keep in mind, existing code includes code that may reside in
private repositories (and is yet to be submitted) or code that has yet to be
migrated from Quagga to FRR.
That said, compatibility measures can (and should) be removed when either:
* they become a significant burden, e.g. when data structures change and
the compatibility measure would need a complex adaptation layer or becomes
* they become a significant burden, e.g. when data structures change and the
compatibility measure would need a complex adaptation layer or becomes
flat-out impossible
* some measure of time (dependent on the specific case) has passed, so that
the compatibility grace period is considered expired.
* some measure of time (dependent on the specific case) has passed, so that the
compatibility grace period is considered expired.
In all cases, compatibility pieces should be marked with compiler/preprocessor
annotations to print warnings at compile time, pointing to the appropriate
update path. A `-Werror` build should fail if compatibility bits are used.
### Miscellaneous
When in doubt, follow the guidelines in the Linux kernel style guide, or ask on
the development mailing list / public Slack instance.