u8 id;                     /* Id of this connection within its unixShmNode */
#endif
};

/*
** Constants used for locking
*/
#define UNIX_SHM_BASE      81        /* Byte offset of the first lock byte */
#define UNIX_SHM_DMS       80        /* The deadman switch lock */

#ifdef SQLITE_DEBUG
/*
** Return a pointer to a nul-terminated string in static memory that
** describes a locking mask.  The string is of the form "MSABCD" with
** each character representing a lock.  "M" for MUTEX, "S" for DMS, 
** and "A" through "D" for the region locks.  If a lock is held, the

  u8 id;                     /* Id of this connection within its unixShmNode */
#endif
};

/*
** Constants used for locking
*/
#define UNIX_SHM_BASE   ((18+SQLITE_SHM_NLOCK)*4)         /* first lock byte */
#define UNIX_SHM_DMS    (UNIX_SHM_BASE+SQLITE_SHM_NLOCK)  /* deadman switch */

#ifdef SQLITE_DEBUG
/*
** Return a pointer to a nul-terminated string in static memory that
** describes a locking mask.  The string is of the form "MSABCD" with
** each character representing a lock.  "M" for MUTEX, "S" for DMS, 
** and "A" through "D" for the region locks.  If a lock is held, the

** implement a loop.  This test used to be on every single instruction,
** but that meant we more testing that we needed.  By only testing the
** flag on jump instructions, we get a (small) speed improvement.
*/
#define CHECK_FOR_INTERRUPT \
   if( db->u1.isInterrupted ) goto abort_due_to_interrupt;

#ifdef SQLITE_DEBUG
static int fileExists(sqlite3 *db, const char *zFile){
  int res = 0;
  int rc = SQLITE_OK;
#ifdef SQLITE_TEST
  /* If we are currently testing IO errors, then do not call OsAccess() to
  ** test for the presence of zFile. This is because any IO error that
  ** occurs here will not be reported, causing the test to fail.
  */
  extern int sqlite3_io_error_pending;
  if( sqlite3_io_error_pending<=0 )
#endif
    rc = sqlite3OsAccess(db->pVfs, zFile, SQLITE_ACCESS_EXISTS, &res);
  return (res && rc==SQLITE_OK);
}
#endif

#ifndef NDEBUG
/*
** This function is only called from within an assert() expression. It
** checks that the sqlite3.nTransaction variable is correctly set to
** the number of non-transaction savepoints currently in the 
** linked list starting at sqlite3.pSavepoint.
................................................................................
  CHECK_FOR_INTERRUPT;
  sqlite3VdbeIOTraceSql(p);
#ifndef SQLITE_OMIT_PROGRESS_CALLBACK
  checkProgress = db->xProgress!=0;
#endif
#ifdef SQLITE_DEBUG
  sqlite3BeginBenignMalloc();
  if( p->pc==0 
   && ((p->db->flags & SQLITE_VdbeListing) || fileExists(db, "vdbe_explain"))
  ){
    int i;
    printf("VDBE Program Listing:\n");
    sqlite3VdbePrintSql(p);
    for(i=0; i<p->nOp; i++){
      sqlite3VdbePrintOp(stdout, i, &aOp[i]);
    }
  }
  if( fileExists(db, "vdbe_trace") ){
    p->trace = stdout;
  }
  sqlite3EndBenignMalloc();
#endif
  for(pc=p->pc; rc==SQLITE_OK; pc++){
    assert( pc>=0 && pc<p->nOp );
    if( db->mallocFailed ) goto no_mem;
#ifdef VDBE_PROFILE
    origPc = pc;
................................................................................
    if( p->trace ){
      if( pc==0 ){
        printf("VDBE Execution Trace:\n");
        sqlite3VdbePrintSql(p);
      }
      sqlite3VdbePrintOp(p->trace, pc, pOp);
    }
    if( p->trace==0 && pc==0 ){
      sqlite3BeginBenignMalloc();
      if( fileExists(db, "vdbe_sqltrace") ){
        sqlite3VdbePrintSql(p);
      }
      sqlite3EndBenignMalloc();
    }
#endif
      

    /* Check to see if we need to simulate an interrupt.  This only happens
    ** if we have a special test build.
    */
#ifdef SQLITE_TEST

** implement a loop.  This test used to be on every single instruction,
** but that meant we more testing that we needed.  By only testing the
** flag on jump instructions, we get a (small) speed improvement.
*/
#define CHECK_FOR_INTERRUPT \
   if( db->u1.isInterrupted ) goto abort_due_to_interrupt;


















#ifndef NDEBUG
/*
** This function is only called from within an assert() expression. It
** checks that the sqlite3.nTransaction variable is correctly set to
** the number of non-transaction savepoints currently in the 
** linked list starting at sqlite3.pSavepoint.
................................................................................
  CHECK_FOR_INTERRUPT;
  sqlite3VdbeIOTraceSql(p);
#ifndef SQLITE_OMIT_PROGRESS_CALLBACK
  checkProgress = db->xProgress!=0;
#endif
#ifdef SQLITE_DEBUG
  sqlite3BeginBenignMalloc();

  if( p->pc==0  && (p->db->flags & SQLITE_VdbeListing)!=0 ){

    int i;
    printf("VDBE Program Listing:\n");
    sqlite3VdbePrintSql(p);
    for(i=0; i<p->nOp; i++){
      sqlite3VdbePrintOp(stdout, i, &aOp[i]);
    }
  }



  sqlite3EndBenignMalloc();
#endif
  for(pc=p->pc; rc==SQLITE_OK; pc++){
    assert( pc>=0 && pc<p->nOp );
    if( db->mallocFailed ) goto no_mem;
#ifdef VDBE_PROFILE
    origPc = pc;
................................................................................
    if( p->trace ){
      if( pc==0 ){
        printf("VDBE Execution Trace:\n");
        sqlite3VdbePrintSql(p);
      }
      sqlite3VdbePrintOp(p->trace, pc, pOp);
    }







#endif
      

    /* Check to see if we need to simulate an interrupt.  This only happens
    ** if we have a special test build.
    */
#ifdef SQLITE_TEST