text: /* **********************************************************
   * Copyright (c) 2007-2008 VMware, Inc.  All rights reserved.
   * **********************************************************/
  
  /*
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions are met:
   * 
   * * Redistributions of source code must retain the above copyright notice,
   *   this list of conditions and the following disclaimer.
   * 
   * * Redistributions in binary form must reproduce the above copyright notice,
   *   this list of conditions and the following disclaimer in the documentation
   *   and/or other materials provided with the distribution.
   * 
   * * Neither the name of VMware, Inc. nor the names of its contributors may be
   *   used to endorse or promote products derived from this software without
   *   specific prior written permission.
   * 
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
   * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   * ARE DISCLAIMED. IN NO EVENT SHALL VMWARE, INC. OR CONTRIBUTORS BE LIABLE
   * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
   * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
   * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
   * DAMAGE.
   */
  
  #include "dr_api.h"
  
  static
  dr_emit_flags_t bb_event(void *drcontext, void* tag, instrlist_t *bb, bool for_trace, bool translating)
  {
      instr_t *instr, *next_instr, *next_next_instr;
      static app_pc target = NULL;
      
      /* Look for pattern: nop; nop; call direct; */
      for (instr = instrlist_first(bb);
           instr != NULL; instr = next_instr) {
          next_instr = instr_get_next(instr);
          if (next_instr != NULL)
              next_next_instr = instr_get_next(next_instr);
          else
              next_next_instr = NULL;
  
          if (instr_is_nop(instr) && 
              next_instr != NULL && instr_is_nop(next_instr) && 
              instr_is_call_direct(next_next_instr)) {
  
              /* The first nop followed by a direct call is a marker
               * for the function we want to call.
               */
              if (target == NULL) {
                  target = instr_get_branch_target_pc(next_next_instr);
              }
              /* The second nop followd by a direct call is a marker
               * for the call we want to modify.
               */
              else {
                  instr_set_branch_target_pc(next_next_instr, target);
              }
  
              break;
          }
      }
  
      return DR_EMIT_DEFAULT;
  }
  
  DR_EXPORT
  void dr_init(client_id_t id)
  {
      dr_register_bb_event(bb_event);
  }
  