1 files changed, 98 insertions, 0 deletions
diff --git a/libpager/pager-attr.c b/libpager/pager-attr.c
new file mode 100644
index 00000000..cbc1533f
--- /dev/null
+++ b/libpager/pager-attr.c
@@ -0,0 +1,98 @@
+/* Changing pager attributes synchronously
+   Copyright (C) 1994, 1996 Free Software Foundation
+
+   This program is free software; you can redistribute it and/or
+   modify it under the terms of the GNU General Public License as
+   published by the Free Software Foundation; either version 2, or (at
+   your option) any later version.
+
+   This program is distributed in the hope that it will be useful, but
+   WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
+
+#include "priv.h"
+#include <assert.h>
+
+/* Change the attributes of the memory object underlying pager P.
+   Args MAY_CACHE and COPY_STRATEGY are as for 
+   memory_object_change_atributes.  Wait for the kernel to report completion
+   off WAIT is set.*/
+void
+pager_change_attributes (struct pager *p,
+ 			 boolean_t may_cache,
+ 			 memory_object_copy_strategy_t copy_strategy,
+			 int wait)
+{
+  struct attribute_request *ar = 0;
+  
+  mutex_lock (&p->interlock);
+
+  /* If there's nothing to do we might be able to return.  However,
+     if the user asked us to wait, and there are pending changes,
+     then we have to do the work anyway because we must follow the
+     pending change.  */
+  if (p->may_cache == may_cache && p->copy_strategy == copy_strategy
+      && ! (p->attribute_requests && wait))
+    {
+      mutex_unlock (&p->interlock);
+      return;
+    }
+
+  p->may_cache = may_cache;
+  p->copy_strategy = copy_strategy;
+  
+  if (p->pager_state == NOTINIT)
+    {
+      mutex_unlock (&p->interlock);
+      return;
+    }
+
+  if (wait)
+    {
+      for (ar = p->attribute_requests; ar; ar = ar->next)
+	if (ar->may_cache == may_cache 
+	    && ar->copy_strategy == copy_strategy)
+	  {
+	    ar->attrs_pending++;
+	    ar->threads_waiting++;
+	    break;
+	  }
+      if (!ar)
+	{
+	  ar = malloc (sizeof (struct attribute_request));
+	  ar->may_cache = may_cache;
+	  ar->copy_strategy = copy_strategy;
+	  ar->attrs_pending = 1;
+	  ar->threads_waiting = 1;
+	  ar->next = p->attribute_requests;
+	  if (ar->next)
+	    ar->next->prevp = &ar->next;
+	  ar->prevp = &p->attribute_requests;
+	  p->attribute_requests = ar;
+	}
+    }      
+
+  memory_object_change_attributes (p->memobjcntl, may_cache, copy_strategy,
+				   wait ? p->port.port_right : MACH_PORT_NULL);
+  
+  if (wait)
+    {
+      while (ar->attrs_pending)
+	condition_wait (&p->wakeup, &p->interlock);
+
+      if (! --ar->threads_waiting)
+	{
+	  *ar->prevp = ar->next;
+	  if (ar->next)
+	    ar->next->prevp = ar->prevp;
+	  free (ar);
+	}
+    }
+  
+  mutex_unlock (&p->interlock);
+}