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")
Unified · Split
| @@ -189,7 +189,7 @@ struct __packed pucan_rx_msg { · 188 unmodified lines | |||
| 189 | u8 client; | 189 | u8 client; |
| 190 | __le16 flags; | 190 | __le16 flags; |
| 191 | __le32 can_id; | 191 | __le32 can_id; |
| 192 | u8 d[0]; | 192 | u8 d[]; |
| 193 | }; | 193 | }; |
| 194 | 194 | ||
| 195 | /* uCAN error types */ | 195 | /* uCAN error types */ |
| @@ -266,7 +266,7 @@ struct __packed pucan_tx_msg { · 70 unmodified lines | |||
| 266 | u8 client; | 266 | u8 client; |
| 267 | __le16 flags; | 267 | __le16 flags; |
| 268 | __le32 can_id; | 268 | __le32 can_id; |
| 269 | u8 d[0]; | 269 | u8 d[]; |
| 270 | }; | 270 | }; |
| 271 | 271 | ||
| 272 | /* build the cmd opcode_channel field with respect to the correct endianness */ | 272 | /* build the cmd opcode_channel field with respect to the correct endianness */ |