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ti_wilink_st.h: Replace zero-length array with flexible-array member

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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>
This commit is contained in:
Gustavo A. R. Silva 2020-03-23 19:25:06 -05:00
parent 16c3380f8c
commit 4ea19ecf32
1 changed files with 3 additions and 3 deletions
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6
include/linux/ti_wilink_st.h
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@ -295,7 +295,7 @@ struct bts_header {
u32 magic;
u32 version;
u8 future[24];
u8 actions[0];
u8 actions[];
} __attribute__ ((packed));
/**
@ -305,7 +305,7 @@ struct bts_header {
struct bts_action {
u16 type;
u16 size;
u8 data[0];
u8 data[];
} __attribute__ ((packed));
struct bts_action_send {
@ -315,7 +315,7 @@ struct bts_action_send {
struct bts_action_wait {
u32 msec;
u32 size;
u8 data[0];
u8 data[];
} __attribute__ ((packed));
struct bts_action_delay {