(store_map):

  If we can't map STORE directly, and it has a source file, try to map that
    instead.

1 files changed, 48 insertions, 3 deletions

diff --git a/libstore/map.c b/libstore/map.c
index 4ba779ea..4ac8ce98 100644
--- a/libstore/map.c
+++ b/libstore/map.c
@@ -18,15 +18,60 @@
    along with this program; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111, USA. */
 
+#include <hurd.h>
+#include <hurd/io.h>
+
 #include "store.h"
 
 /* Return a memory object paging on STORE.  [among other reasons,] this may
    fail because store contains non-contiguous regions on the underlying
    object.  In such a case you can try calling some of the routines below to
    get a pager.  */
-error_t store_map (const struct store *store, vm_prot_t prot, mach_port_t *memobj)
+error_t store_map (const struct store *store, vm_prot_t prot,
+		   mach_port_t *memobj)
 {
-  error_t (*map) (const struct store *store, vm_prot_t prot, mach_port_t *memobj) =
+  error_t (*map) (const struct store *store, vm_prot_t prot,
+		  mach_port_t *memobj) =
     store->class->map;
-  return map ? (*map) (store, prot, memobj) : EOPNOTSUPP;
+  error_t err = map ? (*map) (store, prot, memobj) : EOPNOTSUPP;
+
+  if (err == EOPNOTSUPP && store->source != MACH_PORT_NULL)
+    /* Can't map the store directly, but we know it represents the file
+       STORE->source, so we can try mapping that instead.  */
+    {
+      mach_port_t rd_memobj, wr_memobj;
+      int ro = (store->flags & STORE_HARD_READONLY);
+
+      if ((prot & VM_PROT_WRITE) && ro)
+	return EACCES;
+
+      err = io_map (store->port, &rd_memobj, &wr_memobj);
+      if (! err)
+	{
+	  *memobj = rd_memobj;
+
+	  if (!ro || wr_memobj != MACH_PORT_NULL)
+	    /* If either we or the server think this object is writable, then
+	       the write-memory-object must be the same as the read one (if
+	       we only care about reading, then it can be null too).  */
+	    {
+	      if (rd_memobj == wr_memobj)
+		{
+		  if (rd_memobj != MACH_PORT_NULL)
+		    mach_port_mod_refs (mach_task_self (), rd_memobj,
+					MACH_PORT_RIGHT_SEND, -1);
+		}
+	      else
+		{
+		  if (rd_memobj != MACH_PORT_NULL)
+		    mach_port_deallocate (mach_task_self (), rd_memobj);
+		  if (wr_memobj != MACH_PORT_NULL)
+		    mach_port_deallocate (mach_task_self (), wr_memobj);
+		  err = EOPNOTSUPP;
+		}
+	    }
+	}
+    }
+
+  return err;
 }