On Mon, 21 Sep 2020, Denis Efremov wrote:
> One-element and zero-length arrays are deprecated [1]. Kernel
> code should always use "flexible array members" instead, except
> for existing uapi definitions.
>
> The script warns about one-element and zero-length arrays in structs.
>
> [1] commit 68e4cd17e218 ("docs: deprecated.rst: Add zero-length and
> one-element arrays")
>
> Cc: Kees Cook
> Cc: Gustavo A. R. Silva
> Signed-off-by: Denis Efremov
Applied, thanks.
> ---
> 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.
> Changes in v3:
> - exists removed from "depends on patch"
> - position argument fixed in org mode
> - link to the online documentation added to the warning message
>
> 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 ..947fbaff82a9
> --- /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@
> +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
> (https://www.kernel.org/doc/html/latest/process/deprecated.html#zero-length-and-one-element-arrays)"
> +coccilib.report.print_report(p[0], msg)
> +
> +@script: python depends on org@
> +p << r.p;
> +@@
> +
> +msg = "WARNING use flexible-array member instead
> (https://www.kernel.org/doc/html/latest/process/deprecated.html#zero-length-and-one-element-arrays)"
> +coccilib.org.print_todo(p[0], msg)
> --
> 2.26.2
>
>
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