X-Git-Url: http://git.ozlabs.org/?a=blobdiff_plain;f=ccan%2Fcontainer_of%2F_info.c;fp=ccan%2Fcontainer_of%2F_info.c;h=96c12d88cdeb0d27f6ee30ab25c572810623c73d;hb=650c775ff00cccd03fc84e7789a03c51d9839004;hp=0000000000000000000000000000000000000000;hpb=c8acddea39d222312102952e91c32cfe4dd2cea0;p=ccan

diff --git a/ccan/container_of/_info.c b/ccan/container_of/_info.c
new file mode 100644
index 00000000..96c12d88
--- /dev/null
+++ b/ccan/container_of/_info.c
@@ -0,0 +1,47 @@
+#include <stdio.h>
+#include <string.h>
+#include "config.h"
+
+/**
+ * container_of - routine for upcasting
+ *
+ * It is often convenient to create code where the caller registers a pointer
+ * to a generic structure and a callback.  The callback might know that the
+ * pointer points to within a larger structure, and container_of gives a
+ * convenient and fairly type-safe way of returning to the enclosing structure.
+ *
+ * This idiom is an alternative to providing a void * pointer for every
+ * callback.
+ *
+ * Example:
+ *	struct info
+ *	{
+ *		int my_stuff;
+ *		struct timer timer;
+ *	};
+ *
+ *	static void my_timer_callback(struct timer *timer)
+ *	{
+ *		struct info *info = container_of(timer, struct info, timer);
+ *		printf("my_stuff is %u\n", info->my_stuff);
+ *	}
+ *
+ *	int main()
+ *	{
+ *		struct info info = { .my_stuff = 1 };
+ *
+ *		register_timer(&info.timer);
+ *		...
+ */
+int main(int argc, char *argv[])
+{
+	if (argc != 2)
+		return 1;
+
+	if (strcmp(argv[1], "depends") == 0) {
+		printf("ccan/check_type\n");
+		return 0;
+	}
+
+	return 1;
+}