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author | Gustavo A. R. Silva <gustavo@embeddedor.com> | 2020-02-28 07:47:58 -0600 |
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committer | Marcel Holtmann <marcel@holtmann.org> | 2020-02-28 14:51:30 +0100 |
commit | 8788a1ee070ab9984015ac6ab6af49f2fbfb2cb3 (patch) | |
tree | bd8931aecd4b7a0a68e257173d00d5cd076f21fe /Documentation | |
parent | 4b127bd5f2cc1b2da041f472dab6dc729cdd4711 (diff) | |
download | linux-8788a1ee070ab9984015ac6ab6af49f2fbfb2cb3.tar.bz2 |
6lowpan: Replace zero-length array with flexible-array member
The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:
struct foo {
int stuff;
struct boo array[];
};
By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure, which
will help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.
Also, notice that, dynamic memory allocations won't be affected by
this change:
"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]
This issue was found with the help of Coccinelle.
[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour")
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Diffstat (limited to 'Documentation')
0 files changed, 0 insertions, 0 deletions