Hi,
On 9/12/20 5:43 PM, Julia Lawall wrote:
>
>
> On Mon, 10 Aug 2020, Denis Efremov wrote:
>
>> Commit 68e4cd17e218 ("docs: deprecated.rst: Add zero-length and one-element
>> arrays") marks one-element and zero-length arrays as deprecated. Kernel
>> code should always use "flexible array members" instead.
>>
>> The script warns about one-element and zero-length arrays in structs.
>>
>> Cc: Kees Cook <keesc...@chromium.org>
>> Cc: Gustavo A. R. Silva <gustavo...@kernel.org>
>> Signed-off-by: Denis Efremov <efre...@linux.com>
>> ---
>> Changes in v2:
>> - all uapi headers are now filtered-out. Unfortunately, coccinelle
>> doesn't provide structure names in Location.current_element.
>> For structures the field is always "something_else". Thus, there is
>> no easy way to create a list of existing structures in uapi headers
>> and suppress the warning only for them, but not for the newly added
>> uapi structures.
>> - The pattern doesn't require 2+ fields in a structure/union anymore.
>> Now it also checks single field structures/unions.
>> - The pattern simplified and now uses disjuction in array elements
>> (Thanks, Markus)
>> - Unions are removed from patch mode
>> - one-element arrays are removed from patch mode. Correct patch may
>> involve turning the array to a simple field instead of a flexible
>> array.
>>
>> On the current master branch, the rule generates:
>> - context: https://gist.github.com/evdenis/e2b4323491f9eff35376372df07f723c
>> - patch: https://gist.github.com/evdenis/46081da9d68ecefd07edc3769cebcf32
>>
>> scripts/coccinelle/misc/flexible_array.cocci | 88 ++++++++++++++++++++
>> 1 file changed, 88 insertions(+)
>> create mode 100644 scripts/coccinelle/misc/flexible_array.cocci
>>
>> diff --git a/scripts/coccinelle/misc/flexible_array.cocci
>> b/scripts/coccinelle/misc/flexible_array.cocci
>> new file mode 100644
>> index 000000000000..bf6dcda1783e
>> --- /dev/null
>> +++ b/scripts/coccinelle/misc/flexible_array.cocci
>> @@ -0,0 +1,88 @@
>> +// SPDX-License-Identifier: GPL-2.0-only
>> +///
>> +/// Zero-length and one-element arrays are deprecated, see
>> +/// Documentation/process/deprecated.rst
>> +/// Flexible-array members should be used instead.
>> +///
>> +//
>> +// Confidence: High
>> +// Copyright: (C) 2020 Denis Efremov ISPRAS.
>> +// Comments:
>> +// Options: --no-includes --include-headers
>> +
>> +virtual context
>> +virtual report
>> +virtual org
>> +virtual patch
>> +
>> +@initialize:python@
>> +@@
>> +def relevant(positions):
>> + for p in positions:
>> + if "uapi" in p.file:
>> + return False
>> + return True
>> +
>> +@r depends on !patch@
>> +identifier name, array;
>> +type T;
>> +position p : script:python() { relevant(p) };
>> +@@
>> +
>> +(
>> + struct name {
>> + ...
>> +* T array@p[\(0\|1\)];
>> + };
>> +|
>> + struct {
>> + ...
>> +* T array@p[\(0\|1\)];
>> + };
>> +|
>> + union name {
>> + ...
>> +* T array@p[\(0\|1\)];
>> + };
>> +|
>> + union {
>> + ...
>> +* T array@p[\(0\|1\)];
>> + };
>> +)
>> +
>> +@depends on patch exists@
>
> exists is not necessary here. There are not multiple control-flow paths
> through a structure declaration.
>
>> +identifier name, array;
>> +type T;
>> +position p : script:python() { relevant(p) };
>> +@@
>> +
>> +(
>> + struct name {
>> + ...
>> + T array@p[
>> +- 0
>> + ];
>> + };
>> +|
>> + struct {
>> + ...
>> + T array@p[
>> +- 0
>> + ];
>> + };
>> +)
>> +
>> +@script: python depends on report@
>> +p << r.p;
>> +@@
>> +
>> +msg = "WARNING: use flexible-array member instead"
>> +coccilib.report.print_report(p[0], msg)
>> +
>> +@script: python depends on org@
>> +p << r.p;
>> +@@
>> +
>> +msg = "WARNING: use flexible-array member instead"
>> +coccilib.org.print_todo(p, msg)
>
> This should be coccilib.org.print_todo(p[0], msg)
>
Thanks, I will send v3 with fixes and proper links to online documentation.
Regards,
Denis
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