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 <[email protected]>
Cc: Gustavo A. R. Silva <[email protected]>
Signed-off-by: Denis Efremov <[email protected]>
---
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 000000000000..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
