Index: src/os_common.h
==================================================================
--- src/os_common.h
+++ src/os_common.h
@@ -28,14 +28,17 @@
 #ifdef MEMORY_DEBUG
 # error "The MEMORY_DEBUG macro is obsolete.  Use SQLITE_DEBUG instead."
 #endif
 
 #ifdef SQLITE_DEBUG
-int sqlite3OSTrace = 0;
-#define OSTRACE(X)          if( sqlite3OSTrace ) sqlite3DebugPrintf X
+# ifndef SQLITE_DEBUG_OS_TRACE
+#   define SQLITE_DEBUG_OS_TRACE 0
+# endif
+  int sqlite3OSTrace = SQLITE_DEBUG_OS_TRACE;
+# define OSTRACE(X)          if( sqlite3OSTrace ) sqlite3DebugPrintf X
 #else
-#define OSTRACE(X)
+# define OSTRACE(X)
 #endif
 
 /*
 ** Macros for performance tracing.  Normally turned off.  Only works
 ** on i486 hardware.

Index: src/os_win.c
==================================================================
--- src/os_win.c
+++ src/os_win.c
@@ -2450,15 +2450,17 @@
   zConverted = convertUtf8Filename(zFilename);
   if( zConverted==0 ){
     return SQLITE_NOMEM;
   }
   if( isNT() ){
+    int cnt = 0;
     WIN32_FILE_ATTRIBUTE_DATA sAttrData;
     memset(&sAttrData, 0, sizeof(sAttrData));
-    if( GetFileAttributesExW((WCHAR*)zConverted,
+    while( (rc = GetFileAttributesExW((WCHAR*)zConverted,
                              GetFileExInfoStandard, 
-                             &sAttrData) ){
+                             &sAttrData)) && rc==0 && retryIoerr(&cnt) ){}
+    if( rc ){
       /* For an SQLITE_ACCESS_EXISTS query, treat a zero-length file
       ** as if it does not exist.
       */
       if(    flags==SQLITE_ACCESS_EXISTS
           && sAttrData.nFileSizeHigh==0