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-rw-r--r--src/shared/util.h11
1 files changed, 11 insertions, 0 deletions
diff --git a/src/shared/util.h b/src/shared/util.h
index 17ffd19f55..0246dfd826 100644
--- a/src/shared/util.h
+++ b/src/shared/util.h
@@ -59,6 +59,17 @@ typedef struct dual_timestamp {
#define USEC_PER_MONTH (2629800ULL*USEC_PER_SEC)
#define USEC_PER_YEAR (31557600ULL*USEC_PER_SEC)
+/*
+ * container_of - cast a member of a structure out to the containing structure
+ * @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) ({ \
+ const typeof( ((type *)0)->member ) *__mptr = (ptr); \
+ (type *)( (char *)__mptr - offsetof(type,member) );})
+
/* What is interpreted as whitespace? */
#define WHITESPACE " \t\n\r"
#define NEWLINE "\n\r"