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23 October 2021, 00:29:24 UTC
Revision 5a58ec8cfc8621f5bdbd610202f62f817e5da204 authored by Gustavo A. R. Silva on 23 March 2020, 21:45:36 UTC, committed by Gustavo A. R. Silva on 18 April 2020, 20:44:54 UTC 
blk_types: 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>
1 parent f36aaf8
History
Tip revision: 5a58ec8cfc8621f5bdbd610202f62f817e5da204 authored by Gustavo A. R. Silva on 23 March 2020, 21:45:36 UTC
blk_types: Replace zero-length array with flexible-array member
Tip revision: 5a58ec8
File Mode Size
include
.gitignore -rw-r--r-- 94 bytes
Kconfig -rw-r--r-- 7.1 KB
Makefile -rw-r--r-- 2.9 KB
default_cpio_list -rw-r--r-- 153 bytes
gen_init_cpio.c -rw-r--r-- 12.8 KB
gen_initramfs.sh -rwxr-xr-x 5.7 KB
initramfs_data.S -rw-r--r-- 1.2 KB
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