diff options
| author | Tom Hughes <tomhughes@chromium.org> | 2022-09-08 14:36:23 -0700 |
|---|---|---|
| committer | Chromeos LUCI <chromeos-scoped@luci-project-accounts.iam.gserviceaccount.com> | 2022-09-13 18:11:34 +0000 |
| commit | d596ff9b5b915856b6bc54c3452d2b5d0abda579 (patch) | |
| tree | 6d67f321d56e77693b9559c0b4ef607ed58b6259 | |
| parent | e780253aceceee70d83470bf6d23cb017fa968c1 (diff) | |
| download | chrome-ec-d596ff9b5b915856b6bc54c3452d2b5d0abda579.tar.gz | |
ec_commands: Add flexible array member support for C and C++
This change allows us to use flexible array members in both C and C++.
BRANCH=none
BUG=b:234181908
TEST=./util/compare_build.sh -b all -j 120
=> MATCH
Signed-off-by: Tom Hughes <tomhughes@chromium.org>
Change-Id: Ia62b27507cebbe14c9f5f618a6cf1133859cbe92
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/3893044
Reviewed-by: Yuval Peress <peress@google.com>
| -rw-r--r-- | include/ec_commands.h | 34 |
1 files changed, 21 insertions, 13 deletions
diff --git a/include/ec_commands.h b/include/ec_commands.h index 667212f12e..4fbcb6626c 100644 --- a/include/ec_commands.h +++ b/include/ec_commands.h @@ -73,6 +73,20 @@ extern "C" { #endif +/** + * Constant for creation of flexible array members that work in both C and + * C++. Flexible array members were added in C99 and are not part of the C++ + * standard. However, clang++ and g++ support them in C++. + * When compiling C code, flexible array members are not allowed to appear + * in an otherwise empty struct, so we use the GCC zero-length array + * extension that works with both clang and gcc. + */ +#ifdef __cplusplus +#define FLEXIBLE_ARRAY_MEMBER_SIZE +#else +#define FLEXIBLE_ARRAY_MEMBER_SIZE 0 +#endif + /* * Current version of this protocol * @@ -1745,14 +1759,14 @@ struct ec_params_flash_write { uint32_t offset; uint32_t size; /* Followed by data to write. This union allows accessing an - * underlying buffer as uint32s or uint8s for convenience. This does not - * increase the size of the struct. + * underlying buffer as uint32s or uint8s for convenience. */ union { - uint32_t words32[0]; - uint8_t bytes[0]; + uint32_t words32[FLEXIBLE_ARRAY_MEMBER_SIZE]; + uint8_t bytes[FLEXIBLE_ARRAY_MEMBER_SIZE]; } data; } __ec_align4; +BUILD_ASSERT(member_size(struct ec_params_flash_write, data) == 0); /* Erase flash */ #define EC_CMD_FLASH_ERASE 0x0013 @@ -1970,18 +1984,12 @@ struct ec_params_rand_num { struct ec_response_rand_num { /** - * generated random numbers in the range of 1 to EC_MAX_INSIZE. The size - * of this is set to 1 in order to support C++ compilation. The true + * generated random numbers in the range of 1 to EC_MAX_INSIZE. The true * size of rand is determined by ec_params_rand_num's num_rand_bytes. */ - uint8_t rand[1]; + uint8_t rand[FLEXIBLE_ARRAY_MEMBER_SIZE]; } __ec_align1; - -/* C++ requires all structs to be at least 1 byte long. Since struct - * ec_response_rand_num will never be used with num_rand_bytes == 0 (from - * ec_params_rand_num) it is set to always be at least 1. - */ -BUILD_ASSERT(sizeof(struct ec_response_rand_num) == 1); +BUILD_ASSERT(sizeof(struct ec_response_rand_num) == 0); /** * Get information about the key used to sign the RW firmware. |