Initial revision

kernel/dummy.c

@@ -0,0 +1,86 @@
+/* A dummy task. Used to safely remove old tasks, and get notices if they get
+ * called by accident (i.e., because of some bug...).
+ * 
+ * Created:
+ *   Jul 27, 2004   by Jorrit N. Herder
+ */
+
+#include "kernel.h" 
+#include "proc.h" 
+#include <minix/com.h>
+
+/* Allocated space for the global variables. */
+message m_in;		/* the input message itself */
+message m_out;		/* the output message used for reply */
+int who;		/* caller's proc number */
+int callnr;		/* system call number */
+
+/* Declare some local functions. */
+FORWARD _PROTOTYPE(void get_work, (void)				);
+FORWARD _PROTOTYPE(void reply, (int whom, int result)			);
+
+
+/*===========================================================================*
+ *                             dummy_task                                    *
+ *===========================================================================*/
+PUBLIC void dummy_task()
+{
+/* This is the main routine of this service. In principle this should block
+ * forever on getting new work - the dummy task is not supposed to be called.
+ * If new work is received, somehow, diagnostics are printed.  
+ */
+    int result;                 
+
+    /* kprintf("DUMMY: do nothing kernel task started (proc. nr %d).\n",
+    	proc_number(proc_ptr)); */
+
+    /* Main loop - get work and do it, forever. */         
+    while (TRUE) {              
+
+        /* Wait for incoming message, sets 'callnr' and 'who'. */
+        get_work();
+
+        /* There is work to do! (re)set some variables first. */
+        result = EINVAL;	/* illegal send to dummy task */
+
+	/* Print diagnostics: this was not supposed to happen. */
+	kprintf("Dummy task: request received from %d.\n", who);
+
+	/* Finally send reply message, unless disabled. */
+	if (result != EDONTREPLY) {
+	    reply(who, result);
+        }
+    }
+}
+
+
+/*===========================================================================*
+ *				   get_work                                  *
+ *===========================================================================*/
+PRIVATE void get_work()
+{
+    int status = 0;
+    status = receive(ANY, &m_in);   /* this blocks until message arrives */
+    if (OK != status)
+        kprintf("Dummy task failed to receive message: %d", status);
+    who = m_in.m_source;        /* message arrived! set sender */
+    callnr = m_in.m_type;       /* set function call number */
+}
+
+
+/*===========================================================================*
+ *				reply					     *
+ *===========================================================================*/
+PRIVATE void reply(who, result)
+int who;                           	/* destination */
+int result;                           	/* report result to replyee */
+{
+    int send_status;
+    m_out.m_type = result;  		/* build reply message */
+    send_status = send(who, &m_out);    /* send the message */
+    if (OK != send_status)
+        kprintf("Dummy task unable to send reply: %d", send_status);
+}
+
+
+