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Date:	Mon, 01 Dec 2008 21:16:30 +0100
From:	Christian Franke <Christian DOT Franke AT t-online DOT de>
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To:	cygwin AT cygwin DOT com
Subject:	Avoid duplicate names in /proc/registry (which may crash find) ?
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When dirent.d_type support is added to /proc/registry (see attachment), 
find 4.4.0-3 crashes on keys with duplicate names.

Testcases:

$ find-with-d_type \
/proc/registry/HKEY_LOCAL_MACHINE/SOFTWARE/Microsoft/ALG/ISV

$ find-with-d_type \
/proc/registry/HKEY_LOCAL_MACHINE/SYSTEM/ControlSet001/Services/Eventlog/Security

These keys contain a key and a value with the same name and readdir() 
returns both (with different d_type).

Possible fix to avoid identical names:


1. Put keys and values in different namespaces, e.g.

/proc/registry/path/name.key
/proc/registry/path/name.val

Drawback: Breaks backward compatibility.


or:

2. In readdir(), record the key names in some set<> or hash-table. If 
(and only if) a duplicate name is detected, return a modified name for 
the value:

/proc/registry/path/name
/proc/registry/path/name%76  ('v')

Drawback: Slows down readdir, introduces alias name for value.


Christian


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Content-Type: text/x-patch;
 name="cygwin-1.7-registry-dirent-d_type.patch"
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="cygwin-1.7-registry-dirent-d_type.patch"

diff --git a/winsup/cygwin/fhandler_registry.cc b/winsup/cygwin/fhandler_registry.cc
index ce4335f..1690427 100644
--- a/winsup/cygwin/fhandler_registry.cc
+++ b/winsup/cygwin/fhandler_registry.cc
@@ -432,7 +432,13 @@ retry:
 
   dir->__d_position++;
   if (dir->__d_position & REG_ENUM_VALUES_MASK)
-    dir->__d_position += 0x10000;
+    {
+      dir->__d_position += 0x10000;
+      de->d_type = DT_REG;
+    }
+  else
+    de->d_type = DT_DIR;
+
   res = 0;
 out:
   syscall_printf ("%d = readdir (%p, %p)", res, dir, de);


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