* [PATCH] checkpatch: Fix the usage of capture group ( ... )
@ 2020-07-13 4:32 Mrinal Pandey
2020-07-13 19:31 ` Lukas Bulwahn
0 siblings, 1 reply; 2+ messages in thread
From: Mrinal Pandey @ 2020-07-13 4:32 UTC (permalink / raw)
To: apw, joe, linux-kernel; +Cc: lukas.bulwahn, skhan, Linux-kernel-mentees
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The usage of "capture group (...)" in the immediate condition after `&&`
results in `$1` being uninitialized. This issues a warning "Use of
uninitialized value $1 in regexp compilation at ./scripts/checkpatch.pl
line 2638".
I noticed this bug while running checkpatch on the set of commits from
v5.7 to v5.8-rc1 of the kernel on the commits with a diff content in
their commit message.
This bug was introduced in the script by commit e518e9a59ec3
("checkpatch: emit an error when there's a diff in a changelog"). It has
been in the script since then.
The author intended to store the match made by capture group in variable
`$1`. This should have contained the name of the file as `[\w/]+` matched.
However, this couldn't be accomplished due to usage of capture group and
`$1` in the same regular expression.
Fix this by placing the capture group in the condition before `&&`.
Thus, `$1` can be initialized to the text that capture group matches
thereby setting it to the desired and required value.
Signed-off-by: Mrinal Pandey <mrinalmni@gmail.com>
---
scripts/checkpatch.pl | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 4c820607540b..e73e998d582a 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -2636,8 +2636,8 @@ sub process {
# Check if the commit log has what seems like a diff which can confuse patch
if ($in_commit_log && !$commit_log_has_diff &&
- (($line =~ m@^\s+diff\b.*a/[\w/]+@ &&
- $line =~ m@^\s+diff\b.*a/([\w/]+)\s+b/$1\b@) ||
+ (($line =~ m@^\s+diff\b.*a/([\w/]+)@ &&
+ $line =~ m@^\s+diff\b.*a/[\w/]+\s+b/$1\b@) ||
$line =~ m@^\s*(?:\-\-\-\s+a/|\+\+\+\s+b/)@ ||
$line =~ m/^\s*\@\@ \-\d+,\d+ \+\d+,\d+ \@\@/)) {
ERROR("DIFF_IN_COMMIT_MSG",
--
2.25.1
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^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] checkpatch: Fix the usage of capture group ( ... )
2020-07-13 4:32 [PATCH] checkpatch: Fix the usage of capture group ( ... ) Mrinal Pandey
@ 2020-07-13 19:31 ` Lukas Bulwahn
0 siblings, 0 replies; 2+ messages in thread
From: Lukas Bulwahn @ 2020-07-13 19:31 UTC (permalink / raw)
To: Mrinal Pandey
Cc: apw, joe, linux-kernel, lukas.bulwahn, skhan, Linux-kernel-mentees
On Mon, 13 Jul 2020, Mrinal Pandey wrote:
> The usage of "capture group (...)" in the immediate condition after `&&`
> results in `$1` being uninitialized. This issues a warning "Use of
> uninitialized value $1 in regexp compilation at ./scripts/checkpatch.pl
> line 2638".
>
> I noticed this bug while running checkpatch on the set of commits from
> v5.7 to v5.8-rc1 of the kernel on the commits with a diff content in
> their commit message.
>
> This bug was introduced in the script by commit e518e9a59ec3
> ("checkpatch: emit an error when there's a diff in a changelog"). It has
> been in the script since then.
>
> The author intended to store the match made by capture group in variable
> `$1`. This should have contained the name of the file as `[\w/]+` matched.
> However, this couldn't be accomplished due to usage of capture group and
> `$1` in the same regular expression.
>
> Fix this by placing the capture group in the condition before `&&`.
> Thus, `$1` can be initialized to the text that capture group matches
> thereby setting it to the desired and required value.
>
> Signed-off-by: Mrinal Pandey <mrinalmni@gmail.com>
> ---
I have discussed the change on the mentees list before. So:
Reviewed-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
I ran ./scripts/checkpatch.pl on:
commit 6b3e0e2e0461 ("perf tools: Support CAP_PERFMON capability")
commit 19ce2321739d ("perf flamegraph: Use /bin/bash for report and record scripts")
before and after applying this patch.
On those two patches, checkpatch.pl emits the warning before,
and does not emit after this change. So:
Tested-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Lukas
> scripts/checkpatch.pl | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
> index 4c820607540b..e73e998d582a 100755
> --- a/scripts/checkpatch.pl
> +++ b/scripts/checkpatch.pl
> @@ -2636,8 +2636,8 @@ sub process {
>
> # Check if the commit log has what seems like a diff which can confuse patch
> if ($in_commit_log && !$commit_log_has_diff &&
> - (($line =~ m@^\s+diff\b.*a/[\w/]+@ &&
> - $line =~ m@^\s+diff\b.*a/([\w/]+)\s+b/$1\b@) ||
> + (($line =~ m@^\s+diff\b.*a/([\w/]+)@ &&
> + $line =~ m@^\s+diff\b.*a/[\w/]+\s+b/$1\b@) ||
> $line =~ m@^\s*(?:\-\-\-\s+a/|\+\+\+\s+b/)@ ||
> $line =~ m/^\s*\@\@ \-\d+,\d+ \+\d+,\d+ \@\@/)) {
> ERROR("DIFF_IN_COMMIT_MSG",
> --
> 2.25.1
>
>
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