-pid_t local_child(int argc, char **argv,int *f_in,int *f_out,
- int (*child_main)(int, char **))
+/* This function forks a child which calls child_main(). First,
+ * however, it has to establish communication paths to and from the
+ * newborn child. It creates two socket pairs -- one for writing to
+ * the child (from the parent) and one for reading from the child
+ * (writing to the parent). Since that's four socket ends, each
+ * process has to close the two ends it doesn't need. The remaining
+ * two socket ends are retained for reading and writing. In the
+ * child, the STDIN and STDOUT file descriptors refer to these
+ * sockets. In the parent, the function arguments f_in and f_out are
+ * set to refer to these sockets. */
+pid_t local_child(int argc, char **argv, int *f_in, int *f_out,
+ int (*child_main)(int, char*[]))