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This text describes contribution procedures to systemtap. Please read
and understand them before jumping in. Discussions take place on
the <systemtap@sources.redhat.com> mailing list.
- general
Submissions should be in an easy-to-read diff/patch form, unless
this is inappropriate due to size, relevance, or fraction of novel
content. They should be accompanied by an explanation. The
relevant test suites should be run before and after your changes,
and regressions avoided, explained, or corrected.
Established contributors may be considered for direct GIT write
access. Other contributors should simply pack up the goods into a
plain text email message to the mailing list.
- obvious changes
Trivial, obvious patches may be posted or committed without other
formalities.
- copyright
You must designate the appropriate copyright holder for your
contribution. If not already there, this name should be added by
your patch to the copyright header in the affected files. The
copyright holder is assumed to agree with the general licensing
terms (GPLv2+).
- coding style
Abide by the general formatting of the code you are modifying. The
code base generally follows the GNU standards in usermode code and
the Linux kernel standards in runtime code.
- commit messages
In the git commit message, make the first line a brief (<=50 char)
summary of the patch, and leave the second line blank. If you have
trouble coming up with a concise summary, consider whether your
patch might be better broken into smaller commits.
For trivial changes, the summary alone may be sufficient, but most
commits should include a paragraph or two giving more details about
what the change is and why it is needed. Extra information like
bugzilla numbers and mailing-list discussion links are appreciated
as a supplement, but they are not a replacement for a real
description.
- test suites
As far as practicable, changes should be accompanied by test cases
to prevent future regressions. Tests should be run on at least
x86, and ideally also on some 64-bit platform. The test suite is
located under /src/testsuite and is based on dejagnu. "make check"
runs unprivileged tests only against an uninstalled build tree.
"make installcheck" runs all tests against an installed tree.
Tests that don't require probe execution should go into new or
modified files under the *{ok,ko} directories, which are scanned
by corresponding systemtap.pass1-4/*.exp files. The "ko" tests are
for expected (deliberate) errors.
Tests that execute probes (pass 5) should include their own .exp/.stp
files under any other appropriate systemtap.* testsuite subdirectory.
To run a particular test or set of tests, do:
cd testsuite
make check RUNTESTFLAGS=testname.exp
or
make installcheck RUNTESTFLAGS=testname.exp
To disambiguate among multiple tests with the same name, specify
the directory as well -- for example:
make installcheck RUNTESTFLAGS=systemtap.base/print.exp
- translator
Translator changes can easily invalidate tapsets and user script
code. One must tread carefully and run regression tests rigorously.
Both positive and negative polarity (expect-pass / expect-fail) test
cases may need to be written to assert a bug fix. Script language
changes should be documented in the stap.1 man page and emphasized
in the NEWS file.
- tapsets
Tapset script files should demonstrate effective economy, and avoid
conflicts with user and other tapset code.
It may be necessary to prefix symbols with the tapset name to ensure
systemtap-wide uniqueness. All "external interfaces" expected to be
used by user scripts (or perhaps other tapsets) should be documented
in stapfuncs.5, stapprobes.5. Major or incompatible changes should
be mentioned in the NEWS file.
Internal function, variable, probe identifiers should be prefixed
with "_" for extra uniqueness, and not documented in the man pages.
Tapsets should come with a tests cases that provide good test
coverage. Every alias definition should be tested for pass-2
correctness. Every embedded-C routine should be tested for pass-4
buildability. As they are a security hazard, every tapset
embedded-C routine should be pass-5 stress-tested for response to
erroneous inputs. This applies doubly to /* unprivileged */ ones.
The platforms/architectures against which the tapset was tested
should be published, and ideally asserted by code.
Embedded-C code should avoid making references to the runtime or
other code possibly generated by the translator. Embedded-C code that
dereferences pointers should use deref() type functions to check each
individual operation if there exists a possibility that the function may
be called with invalid pointers or pointer chains.
- runtime
Changes to the runtime can cause problems on different architectures
or kernel versions. Luckily, many code mistakes show up easily in
the pass-4 tests.
- meta
Proposed changes to these guidelines should be discussed on the
mailing list.
- git basics
git clone ssh://sources.redhat.com/git/systemtap.git
# build ; hack hack hack; test
git commit # to your local repository, add nice commit message
git pull # to make sure your copy is up to date & merged
# last minute rebuild; retest
git rebase origin/master # clean git commit of merge history
git diff origin/master # final visual check
git push # to the central one
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