diff options
author | Gustavo A. R. Silva <gustavo@embeddedor.com> | 2020-02-13 10:06:48 -0600 |
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committer | Theodore Ts'o <tytso@mit.edu> | 2020-03-05 20:25:05 -0500 |
commit | 6cfb061fe9e901dd0b6cfa3ed50bc39c81523532 (patch) | |
tree | 8e0a230c5b32d3f5fa40a9679076ec6dc0b8838d /block | |
parent | 92e9c58c5629762001e7294afbdf1283d5c7d2ed (diff) |
ext4: use flexible-array members in struct dx_node and struct dx_root
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>
Link: https://lore.kernel.org/r/20200213160648.GA7054@embeddedor
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Diffstat (limited to 'block')
0 files changed, 0 insertions, 0 deletions