# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1611268717 -3600
# Node ID b1cea6e122d9ab7d1ea259f6552faab66091f21a
# Parent  09653d071a38fbba09a9be4d63d9ded9809dfbd8
Expanded the IPC-related functions, propagating error conditions from flexpage
preparation where the send flexpage has order 0, since this indicates that no
mapping can be performed.

diff -r 09653d071a38 -r b1cea6e122d9 ipc.cc
--- a/ipc.cc	Thu Jan 21 23:36:53 2021 +0100
+++ b/ipc.cc	Thu Jan 21 23:38:37 2021 +0100
@@ -1,22 +1,48 @@
 #include <l4/re/c/dataspace.h>
+#include <l4/re/consts.h>
+#include <l4/sys/task.h>
 
 #include "ipc.h"
 #include "send_flexpage.h"
 
 
 
-/* Make a representation of the flexpage for the IPC system. */
+/* Make an L4 representation of the given flexpage. */
+
+static l4_fpage_t ipc_get_fpage(SendFlexpage *send_flexpage)
+{
+    // NOTE: To introduce flags properly in the flexpage abstractions.
+
+    unsigned long flags = L4_FPAGE_RW;
 
-void ipc_prepare_flexpage(Flexpage *flexpage, unsigned long offset,
-                          l4_addr_t hot_spot, unsigned long flags,
-                          l4_snd_fpage_t *region)
+    return l4_fpage(send_flexpage->base_addr, send_flexpage->order,
+                    (flags & L4RE_DS_MAP_FLAG_RW) ? L4_FPAGE_RW : L4_FPAGE_RO);
+}
+
+/* Make a representation of a flexpage for the IPC system. */
+
+long ipc_prepare_flexpage(Flexpage *flexpage, unsigned long offset,
+                          unsigned long max_offset, l4_addr_t hot_spot,
+                          unsigned long flags, l4_snd_fpage_t *region)
 {
-    SendFlexpage send_flexpage = flexpage->to_send(offset, hot_spot);
+    SendFlexpage send_flexpage = flexpage->to_send(offset, hot_spot, max_offset);
+
+    if (!send_flexpage.order)
+        return -L4_ERANGE;
+
+    region->fpage = ipc_get_fpage(&send_flexpage);
+    region->snd_base = hot_spot;
 
-    region->fpage = l4_fpage(send_flexpage.base_addr, send_flexpage.order,
-                             (flags & L4RE_DS_MAP_FLAG_RW) ? L4_FPAGE_RW
-                                                           : L4_FPAGE_RO);
-    region->snd_base = hot_spot;
+    return L4_EOK;
+}
+
+/* Unmap the given flexpage. */
+
+void ipc_unmap_flexpage(Flexpage *flexpage)
+{
+    SendFlexpage send_flexpage = flexpage->to_unmap();
+
+    l4_task_unmap(L4RE_THIS_TASK_CAP, ipc_get_fpage(&send_flexpage), L4_FP_OTHER_SPACES);
 }
 
 // vim: tabstop=4 expandtab shiftwidth=4
diff -r 09653d071a38 -r b1cea6e122d9 ipc.h
--- a/ipc.h	Thu Jan 21 23:36:53 2021 +0100
+++ b/ipc.h	Thu Jan 21 23:38:37 2021 +0100
@@ -6,8 +6,10 @@
 
 
 
-void ipc_prepare_flexpage(Flexpage *flexpage, unsigned long offset,
-                          l4_addr_t hot_spot, unsigned long flags,
-                          l4_snd_fpage_t *region);
+long ipc_prepare_flexpage(Flexpage *flexpage, unsigned long offset,
+                          unsigned long max_offset, l4_addr_t hot_spot,
+                          unsigned long flags, l4_snd_fpage_t *region);
+
+void ipc_unmap_flexpage(Flexpage *flexpage);
 
 // vim: tabstop=4 expandtab shiftwidth=4
diff -r 09653d071a38 -r b1cea6e122d9 simple_pager.cc
--- a/simple_pager.cc	Thu Jan 21 23:36:53 2021 +0100
+++ b/simple_pager.cc	Thu Jan 21 23:38:37 2021 +0100
@@ -36,9 +36,12 @@
 
     /* Send the flexpage explicitly. */
 
-    ipc_prepare_flexpage(&flexpage, offset, hot_spot, flags, region);
+    long err = ipc_prepare_flexpage(&flexpage, offset, PAGE_SIZE, hot_spot, flags, region);
 
-    long err = complete_Dataspace_map(*region);
+    if (err)
+      return err;
+
+    err = complete_Dataspace_map(*region);
 
     if (err)
       return err;