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-rw-r--r--src/shared/macro.h13
-rw-r--r--src/test/test-util.c19
2 files changed, 27 insertions, 5 deletions
diff --git a/src/shared/macro.h b/src/shared/macro.h
index 2807bc74e8..e6734804bd 100644
--- a/src/shared/macro.h
+++ b/src/shared/macro.h
@@ -79,6 +79,9 @@
#define XCONCATENATE(x, y) x ## y
#define CONCATENATE(x, y) XCONCATENATE(x, y)
+#define UNIQ_T(x, uniq) CONCATENATE(__unique_prefix_, CONCATENATE(x, uniq))
+#define UNIQ __COUNTER__
+
/* Rounds up */
#define ALIGN4(l) (((l) + 3) & ~3)
@@ -122,13 +125,13 @@ static inline unsigned long ALIGN_POWER2(unsigned long u) {
* @ptr: the pointer to the member.
* @type: the type of the container struct this is embedded in.
* @member: the name of the member within the struct.
- *
*/
-#define container_of(ptr, type, member) \
+#define container_of(ptr, type, member) __container_of(UNIQ, (ptr), type, member)
+#define __container_of(uniq, ptr, type, member) \
__extension__ ({ \
- const typeof( ((type *)0)->member ) *__mptr = (ptr); \
- (type *)( (char *)__mptr - offsetof(type,member) ); \
- })
+ const typeof( ((type*)0)->member ) *UNIQ_T(A, uniq) = (ptr); \
+ (type*)( (char *)UNIQ_T(A, uniq) - offsetof(type,member) ); \
+ })
#undef MAX
#define MAX(a,b) \
diff --git a/src/test/test-util.c b/src/test/test-util.c
index 4d9b28f9c8..795f3a1b3d 100644
--- a/src/test/test-util.c
+++ b/src/test/test-util.c
@@ -96,6 +96,24 @@ static void test_max(void) {
assert_cc(MAXSIZE(char, long) == sizeof(long));
}
+static void test_container_of(void) {
+ struct mytype {
+ uint8_t pad1[3];
+ uint64_t v1;
+ uint8_t pad2[2];
+ uint32_t v2;
+ } _packed_ myval = { };
+
+ assert_cc(sizeof(myval) == 17);
+ assert_se(container_of(&myval.v1, struct mytype, v1) == &myval);
+ assert_se(container_of(&myval.v2, struct mytype, v2) == &myval);
+ assert_se(container_of(&container_of(&myval.v2,
+ struct mytype,
+ v2)->v1,
+ struct mytype,
+ v1) == &myval);
+}
+
static void test_first_word(void) {
assert_se(first_word("Hello", ""));
assert_se(first_word("Hello", "Hello"));
@@ -1218,6 +1236,7 @@ int main(int argc, char *argv[]) {
test_streq_ptr();
test_align_power2();
test_max();
+ test_container_of();
test_first_word();
test_close_many();
test_parse_boolean();