]> git.ozlabs.org Git - ccan/blobdiff - ccan/container_of/_info
Rename _info.c to _info: this means we can simple compile *.c.
[ccan] / ccan / container_of / _info
diff --git a/ccan/container_of/_info b/ccan/container_of/_info
new file mode 100644 (file)
index 0000000..4c25c29
--- /dev/null
@@ -0,0 +1,57 @@
+#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:
+ *     #include <stdio.h>
+ *     #include <ccan/container_of/container_of.h>
+ *
+ *     struct timer {
+ *             void *members;
+ *     };
+ *
+ *     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);
+ *             // ...
+ *             return 0;
+ *     }
+ *
+ * Licence: LGPL (2 or any later version)
+ */
+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;
+}