Re: [cocci] [PATCH 2/2] scripts: coccicheck: Separate spatch stdout and stderr

From: Anton Eliasson
Date: Wed Oct 11 2023 - 09:58:08 EST


On 11/10/2023 15.46, Julia Lawall wrote:

On Wed, 11 Oct 2023, Anton Eliasson wrote:

On 10/10/2023 18.11, Julia Lawall wrote:
On Tue, 10 Oct 2023, Anton Eliasson wrote:

On 07/10/2023 21.41, Julia Lawall wrote:
On Tue, 3 Oct 2023, Anton Eliasson wrote:

This helps automating coccicheck runs by discarding stderr and only
looking at the output of stdout. In report mode the only remaining
output on stdout is the initial "Please check for false positives"
message followed by each spatch warning found.
What is getting dropped is the spatch command lines indicating the
semantic patch. Is this desirable?

julia
It's not ideal but it's the best compromise that I have found. The problem
I'm
trying to solve is to be able to diff the output of two coccicheck runs
and
notify the developer if any new warnings were introduced. That requires
the
output to be stable. spatch is always invoked for each cocci file in the
same
order. However, the output from each spatch invocation is not stable as it
examines each source file in an arbitrary order.

My workaround is to sort the output before diffing. The line-by-line
sorted
output only makes sense if the input is one line per warning found and
that is
why I try to discard all output except the single line per spatch warning.
While the terse output doesn't tell which semantic patch file generated
the
warning, it does usually contain the offending file, line number and a
summary
of the issue.
Why does the command line pose a problem for sorting?

julia
You're right. I was overthinking it. Since the sorted command lines will be
common for the two runs they will disappear after diffing.

So at this point I don't have any need for this patch. I'll reach out to you
again if it turns out to be an issue after we have gotten the continuous
integration check in place. Thanks for the feedback and I'm sorry about the
noise.
OK, thanks for the discussion. I was also thinking about whether it could
be possible to make the output always come out in the same order, based on
the name of the analyzed file. Maybe it is possible.

julia

Yes, that might help to preserve some context. The difference between two runs could be presented as a unified diff instead of just lines added. That would probably contain the command line invoking the semantic patch that caused the warning, unless there are too many pre-existent warnings.


Anton



Anton

Anton
Signed-off-by: Anton Eliasson <anton.eliasson@xxxxxxxx>
---
scripts/coccicheck | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/scripts/coccicheck b/scripts/coccicheck
index 95a312730e98..7e7c44125f47 100755
--- a/scripts/coccicheck
+++ b/scripts/coccicheck
@@ -146,8 +146,8 @@ run_cmd_parmap() {
echo $@>>$DEBUG_FILE
$@ 2>>$DEBUG_FILE
else
- echo $@
- $@ 2>&1
+ echo $@ >&2
+ $@
fi

err=$?

--
2.30.2