Index: src/os_win.c
==================================================================
--- src/os_win.c
+++ src/os_win.c
@@ -2922,12 +2922,20 @@
       ** around problems caused by indexing and/or anti-virus software on
       ** Windows systems.
       ** If you are using this code as a model for alternative VFSes, do not
       ** copy this retry logic.  It is a hack intended for Windows only.
       */
+      lastErrno = osGetLastError();
       OSTRACE(("LOCK-PENDING-FAIL file=%p, count=%d, result=%d\n",
                pFile->h, cnt, res));
+      if( lastErrno==ERROR_INVALID_HANDLE ){
+        pFile->lastErrno = lastErrno;
+        rc = SQLITE_IOERR_LOCK;
+        OSTRACE(("LOCK-FAIL file=%p, count=%d, rc=%s\n",
+                 pFile->h, cnt, sqlite3ErrName(rc)));
+        return rc;
+      }
       if( cnt ) sqlite3_win32_sleep(1);
     }
     gotPendingLock = res;
     if( !res ){
       lastErrno = osGetLastError();
@@ -3167,10 +3175,21 @@
         a[1] = winIoerrRetryDelay;
       }
       OSTRACE(("FCNTL file=%p, rc=SQLITE_OK\n", pFile->h));
       return SQLITE_OK;
     }
+#ifdef SQLITE_TEST
+    case SQLITE_FCNTL_WIN32_SET_HANDLE: {
+      LPHANDLE phFile = (LPHANDLE)pArg;
+      HANDLE hOldFile = pFile->h;
+      pFile->h = *phFile;
+      *phFile = hOldFile;
+      OSTRACE(("FCNTL oldFile=%p, newFile=%p, rc=SQLITE_OK\n",
+               hOldFile, pFile->h));
+      return SQLITE_OK;
+    }
+#endif
     case SQLITE_FCNTL_TEMPFILENAME: {
       char *zTFile = 0;
       int rc = winGetTempname(pFile->pVfs, &zTFile);
       if( rc==SQLITE_OK ){
         *(char**)pArg = zTFile;

Index: src/sqlite.h.in
==================================================================
--- src/sqlite.h.in
+++ src/sqlite.h.in
@@ -940,10 +940,16 @@
 ** The [SQLITE_FCNTL_HAS_MOVED] file control interprets its argument as a
 ** pointer to an integer and it writes a boolean into that integer depending
 ** on whether or not the file has been renamed, moved, or deleted since it
 ** was first opened.
 **
+** <li>[[SQLITE_FCNTL_WIN32_SET_HANDLE]]
+** The [SQLITE_FCNTL_WIN32_SET_HANDLE] opcode is used for debugging.  This
+** opcode causes the xFileControl method to swap the file handle with the one
+** pointed to by the pArg argument.  This capability is used during testing
+** and only needs to be supported when SQLITE_TEST is defined.
+**
 ** </ul>
 */
 #define SQLITE_FCNTL_LOCKSTATE               1
 #define SQLITE_GET_LOCKPROXYFILE             2
 #define SQLITE_SET_LOCKPROXYFILE             3
@@ -963,10 +969,11 @@
 #define SQLITE_FCNTL_MMAP_SIZE              18
 #define SQLITE_FCNTL_TRACE                  19
 #define SQLITE_FCNTL_HAS_MOVED              20
 #define SQLITE_FCNTL_SYNC                   21
 #define SQLITE_FCNTL_COMMIT_PHASETWO        22
+#define SQLITE_FCNTL_WIN32_SET_HANDLE       23
 
 /*
 ** CAPI3REF: Mutex Handle
 **
 ** The mutex module within SQLite defines [sqlite3_mutex] to be an

Index: src/test1.c
==================================================================
--- src/test1.c
+++ src/test1.c
@@ -114,10 +114,20 @@
   }else{
     *ppDb = (sqlite3*)sqlite3TestTextToPtr(zA);
   }
   return TCL_OK;
 }
+
+#if SQLITE_OS_WIN
+/*
+** Decode a Win32 HANDLE object.
+*/
+int getWin32Handle(Tcl_Interp *interp, const char *zA, LPHANDLE phFile){
+  *phFile = (HANDLE)sqlite3TestTextToPtr(zA);
+  return TCL_OK;
+}
+#endif
 
 extern const char *sqlite3ErrName(int);
 #define t1ErrorName sqlite3ErrName
 
 /*
@@ -5208,10 +5218,11 @@
   }
 #endif
   return TCL_OK;  
 }
 
+#if SQLITE_OS_WIN
 /*
 ** tclcmd:   file_control_win32_av_retry DB  NRETRY  DELAY
 **
 ** This TCL command runs the sqlite3_file_control interface with
 ** the SQLITE_FCNTL_WIN32_AV_RETRY opcode.
@@ -5241,10 +5252,46 @@
   sqlite3_snprintf(sizeof(z), z, "%d %d %d", rc, a[0], a[1]);
   Tcl_AppendResult(interp, z, (char*)0);
   return TCL_OK;  
 }
 
+/*
+** tclcmd:   file_control_win32_set_handle DB HANDLE
+**
+** This TCL command runs the sqlite3_file_control interface with
+** the SQLITE_FCNTL_WIN32_SET_HANDLE opcode.
+*/
+static int file_control_win32_set_handle(
+  ClientData clientData, /* Pointer to sqlite3_enable_XXX function */
+  Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */
+  int objc,              /* Number of arguments */
+  Tcl_Obj *CONST objv[]  /* Command arguments */
+){
+  sqlite3 *db;
+  int rc;
+  HANDLE hFile = NULL;
+  char z[100];
+
+  if( objc!=3 ){
+    Tcl_AppendResult(interp, "wrong # args: should be \"",
+        Tcl_GetStringFromObj(objv[0], 0), " DB HANDLE", 0);
+    return TCL_ERROR;
+  }
+  if( getDbPointer(interp, Tcl_GetString(objv[1]), &db) ){
+    return TCL_ERROR;
+  }
+  if( getWin32Handle(interp, Tcl_GetString(objv[2]), &hFile) ){
+    return TCL_ERROR;
+  }
+  rc = sqlite3_file_control(db, NULL, SQLITE_FCNTL_WIN32_SET_HANDLE,
+                            (void*)&hFile);
+  sqlite3_snprintf(sizeof(z), z, "%d %p", rc, (void*)hFile);
+  Tcl_AppendResult(interp, z, (char*)0);
+  return TCL_OK;  
+}
+#endif
+
 /*
 ** tclcmd:   file_control_persist_wal DB PERSIST-FLAG
 **
 ** This TCL command runs the sqlite3_file_control interface with
 ** the SQLITE_FCNTL_PERSIST_WAL opcode.
@@ -6470,11 +6517,14 @@
      { "file_control_test",          file_control_test,   0   },
      { "file_control_lasterrno_test", file_control_lasterrno_test,  0   },
      { "file_control_lockproxy_test", file_control_lockproxy_test,  0   },
      { "file_control_chunksize_test", file_control_chunksize_test,  0   },
      { "file_control_sizehint_test",  file_control_sizehint_test,   0   },
+#if SQLITE_OS_WIN
      { "file_control_win32_av_retry", file_control_win32_av_retry,  0   },
+     { "file_control_win32_set_handle", file_control_win32_set_handle, 0  },
+#endif
      { "file_control_persist_wal",    file_control_persist_wal,     0   },
      { "file_control_powersafe_overwrite",file_control_powersafe_overwrite,0},
      { "file_control_vfsname",        file_control_vfsname,         0   },
      { "file_control_tempfilename",   file_control_tempfilename,    0   },
      { "sqlite3_vfs_list",           vfs_list,     0   },

Index: test/win32lock.test
==================================================================
--- test/win32lock.test
+++ test/win32lock.test
@@ -22,11 +22,11 @@
 
 db close
 sqlite3_shutdown
 test_sqlite3_log xLog
 proc xLog {error_code msg} {
-  lappend ::log $msg 
+  lappend ::log $msg
 }
 sqlite3 db test.db
 db eval {PRAGMA mmap_size=0}
 
 do_test win32lock-1.1 {
@@ -125,10 +125,56 @@
   sqlite3_sleep 10
 }
 
 file_control_win32_av_retry db 10 25
 sqlite3_test_control_pending_byte $old_pending_byte
+db close
+forcedelete test.db
+
+sqlite3 db test.db
+sqlite3 db2 test.db
+
+do_test win32lock-3.0 {
+  db eval {
+    CREATE TABLE t1(x);
+    INSERT INTO t1 VALUES(1);
+    INSERT INTO t1 VALUES(2);
+    INSERT INTO t1 VALUES(3);
+  }
+} {}
+
+do_test win32lock-3.1 {
+  db eval {
+    BEGIN EXCLUSIVE;
+    INSERT INTO t1 VALUES(4);
+  }
+} {}
+
+do_test win32lock-3.2 {
+  catchsql {
+    BEGIN EXCLUSIVE;
+    INSERT INTO t1 VALUES(5);
+    COMMIT;
+  } db2
+} {1 {database is locked}}
+
+do_test win32lock-3.3 {
+  db eval {
+    COMMIT;
+  }
+} {}
+
+do_test win32lock-3.4 {
+  set handle [lindex [file_control_win32_set_handle db 0] end]
+  list [catchsql {
+    BEGIN EXCLUSIVE;
+    INSERT INTO t1 VALUES(6);
+    COMMIT;
+  }] [file_control_win32_set_handle db $handle] [sqlite3_extended_errcode db]
+} {{1 {disk I/O error}} {0 0} SQLITE_IOERR_LOCK}
+
+db2 close
 db close
 sqlite3_shutdown
-test_sqlite3_log 
+test_sqlite3_log
 sqlite3_initialize
 finish_test