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* [PATCH] test-lib: unset trace2 parent envvars
@ 2022-01-14  3:33 Josh Steadmon
  2022-01-14  6:01 ` Junio C Hamano
  0 siblings, 1 reply; 5+ messages in thread
From: Josh Steadmon @ 2022-01-14  3:33 UTC (permalink / raw)
  To: git

The trace2 subsystem can inherit certain information from parent
processes via environment variables; e.g., the parent command name and
session ID. This allows trace2 to note when a command is the child
process of another Git process, and to adjust various pieces of output
accordingly.

This behavior breaks certain tests that examine trace2 output when the
tests run as a child of another git process, such as in `git rebase -x
"make test"`.

While we could fix this by unsetting the relevant variables in the
affected tests (currently t0210, t0211, t0212, and t6421), this would
leave other tests vulnerable to similar breakage if new test cases are
added which inspect trace2 output. So fix this in general by unsetting
GIT_TRACE2_PARENT_NAME and GIT_TRACE2_PARENT_SID in test-lib.sh.

Reported-by: Emily Shaffer <emilyshaffer@google.com>
Helped-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Josh Steadmon <steadmon@google.com>
---
 t/test-lib.sh | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/t/test-lib.sh b/t/test-lib.sh
index 0f7a137c7d..e4716b0b86 100644
--- a/t/test-lib.sh
+++ b/t/test-lib.sh
@@ -449,6 +449,8 @@ unset VISUAL EMAIL LANGUAGE $("$PERL_PATH" -e '
 unset XDG_CACHE_HOME
 unset XDG_CONFIG_HOME
 unset GITPERLLIB
+unset GIT_TRACE2_PARENT_NAME
+unset GIT_TRACE2_PARENT_SID
 TEST_AUTHOR_LOCALNAME=author
 TEST_AUTHOR_DOMAIN=example.com
 GIT_AUTHOR_EMAIL=${TEST_AUTHOR_LOCALNAME}@${TEST_AUTHOR_DOMAIN}

base-commit: dcc0cd074f0c639a0df20461a301af6d45bd582e
-- 
2.34.1.703.g22d0c6ccf7-goog


^ permalink raw reply	[flat|nested] 5+ messages in thread

* Re: [PATCH] test-lib: unset trace2 parent envvars
  2022-01-14  3:33 [PATCH] test-lib: unset trace2 parent envvars Josh Steadmon
@ 2022-01-14  6:01 ` Junio C Hamano
  2022-01-18 21:23   ` Josh Steadmon
  2022-01-18 21:29   ` Taylor Blau
  0 siblings, 2 replies; 5+ messages in thread
From: Junio C Hamano @ 2022-01-14  6:01 UTC (permalink / raw)
  To: Josh Steadmon, Jeff Hostetler; +Cc: git

Josh Steadmon <steadmon@google.com> writes:

> This behavior breaks certain tests that examine trace2 output when the
> tests run as a child of another git process, such as in `git rebase -x
> "make test"`.

Well explained.  The paragraph makes it clear how easy to trigger
and get bitten by this problem.

> While we could fix this by unsetting the relevant variables in the
> affected tests (currently t0210, t0211, t0212, and t6421), this would
> leave other tests vulnerable to similar breakage if new test cases are
> added which inspect trace2 output. So fix this in general by unsetting
> GIT_TRACE2_PARENT_NAME and GIT_TRACE2_PARENT_SID in test-lib.sh.

This probably makes sense, but I wonder how it interacts with a user
who runs "cd t && GIT_TRACE2=blah ./t0987-test-this.sh" to trace the
entire test script, though.

> Reported-by: Emily Shaffer <emilyshaffer@google.com>
> Helped-by: Jonathan Tan <jonathantanmy@google.com>
> Signed-off-by: Josh Steadmon <steadmon@google.com>
> ---
>  t/test-lib.sh | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/t/test-lib.sh b/t/test-lib.sh
> index 0f7a137c7d..e4716b0b86 100644
> --- a/t/test-lib.sh
> +++ b/t/test-lib.sh
> @@ -449,6 +449,8 @@ unset VISUAL EMAIL LANGUAGE $("$PERL_PATH" -e '
>  unset XDG_CACHE_HOME
>  unset XDG_CONFIG_HOME
>  unset GITPERLLIB
> +unset GIT_TRACE2_PARENT_NAME
> +unset GIT_TRACE2_PARENT_SID

Hmph.  Have you noticed the more generic "We want to unset almost
everything that begins with GIT_, other than those selected few that
are designed to be used to affect the tests" above the part you
touched?

I am wondering if we should tweak the list there, instead of special
casing these two and these two only. There is a pattern that allows
anything that match "^GIT_(other|TRACE|things)", and I suspect that
the pattern is way too loose (i.e. it allows any garbage to follow,
and by allowing "TRACE", it also catches "TRACE2" because the former
is a prefix of the latter), which is a problem.

^ permalink raw reply	[flat|nested] 5+ messages in thread

* Re: [PATCH] test-lib: unset trace2 parent envvars
  2022-01-14  6:01 ` Junio C Hamano
@ 2022-01-18 21:23   ` Josh Steadmon
  2022-01-18 21:50     ` Junio C Hamano
  2022-01-18 21:29   ` Taylor Blau
  1 sibling, 1 reply; 5+ messages in thread
From: Josh Steadmon @ 2022-01-18 21:23 UTC (permalink / raw)
  To: Junio C Hamano; +Cc: Jeff Hostetler, git

On 2022.01.13 22:01, Junio C Hamano wrote:
> Josh Steadmon <steadmon@google.com> writes:
> 
> > This behavior breaks certain tests that examine trace2 output when the
> > tests run as a child of another git process, such as in `git rebase -x
> > "make test"`.
> 
> Well explained.  The paragraph makes it clear how easy to trigger
> and get bitten by this problem.
> 
> > While we could fix this by unsetting the relevant variables in the
> > affected tests (currently t0210, t0211, t0212, and t6421), this would
> > leave other tests vulnerable to similar breakage if new test cases are
> > added which inspect trace2 output. So fix this in general by unsetting
> > GIT_TRACE2_PARENT_NAME and GIT_TRACE2_PARENT_SID in test-lib.sh.
> 
> This probably makes sense, but I wonder how it interacts with a user
> who runs "cd t && GIT_TRACE2=blah ./t0987-test-this.sh" to trace the
> entire test script, though.

There shouldn't be any problems with this specific use case. I don't see
a valid reason for a test runner to fake GIT_TRACE2_PARENT_{NAME,SID}
though. None of the TRACE2 modes require using any of the PARENT
variables.


> > Reported-by: Emily Shaffer <emilyshaffer@google.com>
> > Helped-by: Jonathan Tan <jonathantanmy@google.com>
> > Signed-off-by: Josh Steadmon <steadmon@google.com>
> > ---
> >  t/test-lib.sh | 2 ++
> >  1 file changed, 2 insertions(+)
> >
> > diff --git a/t/test-lib.sh b/t/test-lib.sh
> > index 0f7a137c7d..e4716b0b86 100644
> > --- a/t/test-lib.sh
> > +++ b/t/test-lib.sh
> > @@ -449,6 +449,8 @@ unset VISUAL EMAIL LANGUAGE $("$PERL_PATH" -e '
> >  unset XDG_CACHE_HOME
> >  unset XDG_CONFIG_HOME
> >  unset GITPERLLIB
> > +unset GIT_TRACE2_PARENT_NAME
> > +unset GIT_TRACE2_PARENT_SID
> 
> Hmph.  Have you noticed the more generic "We want to unset almost
> everything that begins with GIT_, other than those selected few that
> are designed to be used to affect the tests" above the part you
> touched?
> 
> I am wondering if we should tweak the list there, instead of special
> casing these two and these two only. There is a pattern that allows
> anything that match "^GIT_(other|TRACE|things)", and I suspect that
> the pattern is way too loose (i.e. it allows any garbage to follow,
> and by allowing "TRACE", it also catches "TRACE2" because the former
> is a prefix of the latter), which is a problem.

Yes, due to the number of different TRACE2 modes, I figured it was
cleaner to allow them by default and then explicitly unset the ones that
cause trouble for trace parsing tests. But if you prefer to lock down
the list, I can send an alternate fix.


Thanks,
Josh

^ permalink raw reply	[flat|nested] 5+ messages in thread

* Re: [PATCH] test-lib: unset trace2 parent envvars
  2022-01-14  6:01 ` Junio C Hamano
  2022-01-18 21:23   ` Josh Steadmon
@ 2022-01-18 21:29   ` Taylor Blau
  1 sibling, 0 replies; 5+ messages in thread
From: Taylor Blau @ 2022-01-18 21:29 UTC (permalink / raw)
  To: Junio C Hamano; +Cc: Josh Steadmon, Jeff Hostetler, git

On Thu, Jan 13, 2022 at 10:01:07PM -0800, Junio C Hamano wrote:
> Josh Steadmon <steadmon@google.com> writes:
>
> > This behavior breaks certain tests that examine trace2 output when the
> > tests run as a child of another git process, such as in `git rebase -x
> > "make test"`.
>
> Well explained.  The paragraph makes it clear how easy to trigger
> and get bitten by this problem.
>
> > While we could fix this by unsetting the relevant variables in the
> > affected tests (currently t0210, t0211, t0212, and t6421), this would
> > leave other tests vulnerable to similar breakage if new test cases are
> > added which inspect trace2 output. So fix this in general by unsetting
> > GIT_TRACE2_PARENT_NAME and GIT_TRACE2_PARENT_SID in test-lib.sh.
>
> This probably makes sense, but I wonder how it interacts with a user
> who runs "cd t && GIT_TRACE2=blah ./t0987-test-this.sh" to trace the
> entire test script, though.
>
> > Reported-by: Emily Shaffer <emilyshaffer@google.com>
> > Helped-by: Jonathan Tan <jonathantanmy@google.com>
> > Signed-off-by: Josh Steadmon <steadmon@google.com>
> > ---
> >  t/test-lib.sh | 2 ++
> >  1 file changed, 2 insertions(+)
> >
> > diff --git a/t/test-lib.sh b/t/test-lib.sh
> > index 0f7a137c7d..e4716b0b86 100644
> > --- a/t/test-lib.sh
> > +++ b/t/test-lib.sh
> > @@ -449,6 +449,8 @@ unset VISUAL EMAIL LANGUAGE $("$PERL_PATH" -e '
> >  unset XDG_CACHE_HOME
> >  unset XDG_CONFIG_HOME
> >  unset GITPERLLIB
> > +unset GIT_TRACE2_PARENT_NAME
> > +unset GIT_TRACE2_PARENT_SID
>
> Hmph.  Have you noticed the more generic "We want to unset almost
> everything that begins with GIT_, other than those selected few that
> are designed to be used to affect the tests" above the part you
> touched?
>
> I am wondering if we should tweak the list there, instead of special
> casing these two and these two only. There is a pattern that allows
> anything that match "^GIT_(other|TRACE|things)", and I suspect that
> the pattern is way too loose (i.e. it allows any garbage to follow,
> and by allowing "TRACE", it also catches "TRACE2" because the former
> is a prefix of the latter), which is a problem.

I was thinking the same thing, but I suspect that this may truly be
different. That list says we should be able to keep anything that looks
like GIT_TRACE in our environment. So the same should be true of
TRACE2-related variables, I'd think.

But the PARENT_NAME and PARENT_SID variables are (as far as I can tell
from reading around) internal variables that help us piece together the
names of the Git commands we ran.

In other words, excluding all TRACE2 variables goes too far since it
prevents us from being able to `GIT_TRACE2=1 make test`. But we would
want to clear out any internal TRACE2 variables such as PARENT_NAME and
PARENT_SID.

Thanks,
Taylor

^ permalink raw reply	[flat|nested] 5+ messages in thread

* Re: [PATCH] test-lib: unset trace2 parent envvars
  2022-01-18 21:23   ` Josh Steadmon
@ 2022-01-18 21:50     ` Junio C Hamano
  0 siblings, 0 replies; 5+ messages in thread
From: Junio C Hamano @ 2022-01-18 21:50 UTC (permalink / raw)
  To: Josh Steadmon; +Cc: Jeff Hostetler, git

Josh Steadmon <steadmon@google.com> writes:

> Yes, due to the number of different TRACE2 modes, I figured it was
> cleaner to allow them by default and then explicitly unset the ones that
> cause trouble for trace parsing tests.

I think I would agree that it is a better solution, and the design
behind it (which makes me say it is better) should be recorded in
the log message (and possibly in-code comment near the place we
reset them) to help future developers who may add more TRACE2
variables.

Thanks.




^ permalink raw reply	[flat|nested] 5+ messages in thread

end of thread, other threads:[~2022-01-18 21:50 UTC | newest]

Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-01-14  3:33 [PATCH] test-lib: unset trace2 parent envvars Josh Steadmon
2022-01-14  6:01 ` Junio C Hamano
2022-01-18 21:23   ` Josh Steadmon
2022-01-18 21:50     ` Junio C Hamano
2022-01-18 21:29   ` Taylor Blau

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