get/setpriority() and fsync() system calls

kernel/system/priority.c

@@ -0,0 +1,56 @@
+/* The system call implemented in this file:
+ *   m_type:	SYS_SETPRIORITY
+ *
+ * The parameters for this system call are:
+ *    m1_i1:	which
+ *    m1_i2:	who
+ *    m1_i3:	prio
+ */
+
+#include "../kernel.h"
+#include "../system.h"
+#include <minix/type.h>
+#include <sys/resource.h>
+
+/*===========================================================================*
+ *				do_setpriority					*
+ *===========================================================================*/
+PUBLIC int do_setpriority(message *m_ptr)
+{
+	int which_proc, pri, q, niceperq;
+	struct proc *which_procp;
+
+	which_proc = m_ptr->m1_i1;
+	pri  = m_ptr->m1_i2;
+
+	/* pri is currently between PRIO_MIN and PRIO_MAX. We have to
+	 * scale this between MIN_USER_Q and MAX_USER_Q.
+	 */
+
+	if(pri < PRIO_MIN || pri > PRIO_MAX)
+		return EINVAL;
+
+	if(which_proc < 0 || which_proc >= NR_TASKS+NR_PROCS)
+		return EINVAL;
+
+	which_procp = proc_addr(which_proc);
+
+	q = MAX_USER_Q + (pri - PRIO_MIN) * (MIN_USER_Q-MAX_USER_Q+1) / (PRIO_MAX-PRIO_MIN+1);
+
+	/* The below shouldn't happen. */
+	if(q < MAX_USER_Q) q = MAX_USER_Q;
+	if(q > MIN_USER_Q) q = MIN_USER_Q;
+
+	/* max_priority is the base priority. */
+	which_procp->p_max_priority = q;
+	lock_unready(which_procp);
+	which_procp->p_priority = q;
+
+	/* Runnable? Put it (back) on its new run queue. */
+	if(!which_procp->p_rts_flags)
+		lock_ready(which_procp);
+
+	return OK;
+}
+
+