From d68074b8c460de31fae524b67ff4c19e8e56fc2e Mon Sep 17 00:00:00 2001
From: "Michael I. Bushnell" <mib@gnu.org>
Date: Thu, 13 Jan 1994 20:44:45 +0000
Subject: Initial revision

---
 libpager/lock-object.c | 82 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 82 insertions(+)
 create mode 100644 libpager/lock-object.c

(limited to 'libpager/lock-object.c')

diff --git a/libpager/lock-object.c b/libpager/lock-object.c
new file mode 100644
index 00000000..c00f5170
--- /dev/null
+++ b/libpager/lock-object.c
@@ -0,0 +1,82 @@
+/* Synchronous wrapper for memory_object_lock_request
+   Copyright (C) 1993, 1994 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. */
+
+
+/* Request a lock from the kernel.  Parameters are as for
+   memory_object_lock_request.  If SYNC is set, then wait for
+   the operation to fully complete before returning.  */
+void
+lock_object (struct pager *p, 
+	     vm_offset_t offset,
+	     vm_size_t size,
+	     int should_return,
+	     int should_flush,
+	     vm_prot_t lock_value,
+	     int sync)
+{
+  struct lock_request *lr = 0;
+
+  mutex_lock (&p->interlock);
+  if (p->pager_state != NORMAL)
+    {
+      mutex_unlock (&p->interlock);
+      return;
+    }
+  
+  if (sync)
+    {
+      for (lr = p->lock_requests; lr; lr = lr->next)
+	if (lr->start == offset && lr->end == offset + size)
+	  {
+	    lr->locks_pending++;
+	    lr->threads_waiting++;
+	    break;
+	  }
+      if (!lr)
+	{
+	  lr = malloc (sizeof (struct lock_request));
+	  lr->start = offset;
+	  lr->end = offset + size;
+	  lr->pending_writes = 0;
+	  lr->locks_pending = 1;
+	  lr->threads_waiting = 1;
+	  lr->next = p->lock_requests;
+	  if (lr->next)
+	    lr->next->prevp = &lr->next;
+	  lr->prevp = &p->lock_requests;
+	  p->lock_requests = lr;
+	}
+    }
+  
+  memory_object_lock_request (p->memobjcntl, offset, size, should_return,
+			      should_flush, lock_value, 
+			      sync ? p->port.port : MACH_PORT_NULL);
+  
+  if (sync)
+    {
+      while (lr->locks_pending || lr->pending_writes)
+	condition_wait (&p->wakeup, &p->interlock);
+  
+      if (!--lr->threads_waiting)
+	{
+	  *lr->prevp = lr->next;
+	  free (lr);
+	}
+    }
+
+  mutex_unlock (&p->interlock);
+}
-- 
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