** schema change has occurred.  That detail is handled by the
** outer sqlite3_step() wrapper procedure.
*/
static int sqlite3Step(Vdbe *p){
  sqlite3 *db;
  int rc;


  if( p==0 || p->magic!=VDBE_MAGIC_RUN ){
    return SQLITE_MISUSE;
  }

  /* Assert that malloc() has not failed */
  db = p->db;
  assert( !db->mallocFailed );

................................................................................
/*
** This is the top-level implementation of sqlite3_step().  Call
** sqlite3Step() to do most of the work.  If a schema error occurs,
** call sqlite3Reprepare() and try again.
*/
#ifdef SQLITE_OMIT_PARSER
int sqlite3_step(sqlite3_stmt *pStmt){
  int rc;

  Vdbe *v;
  v = (Vdbe*)pStmt;
  sqlite3_mutex_enter(v->db->mutex);
  rc = sqlite3Step(v);
  sqlite3_mutex_leave(v->db->mutex);

  return rc;
}
#else
int sqlite3_step(sqlite3_stmt *pStmt){


  int cnt = 0;
  int rc;
  Vdbe *v = (Vdbe*)pStmt;
  sqlite3 *db = v->db;
  sqlite3_mutex_enter(db->mutex);
  while( (rc = sqlite3Step(v))==SQLITE_SCHEMA
         && cnt++ < 5
         && sqlite3Reprepare(v) ){
    sqlite3_reset(pStmt);
    v->expired = 0;
  }
  if( rc==SQLITE_SCHEMA && v->zSql && db->pErr ){
    /* This case occurs after failing to recompile an sql statement. 
    ** The error message from the SQL compiler has already been loaded 
    ** into the database handle. This block copies the error message 
    ** from the database handle into the statement and sets the statement
    ** program counter to 0 to ensure that when the statement is 
    ** finalized or reset the parser error message is available via
    ** sqlite3_errmsg() and sqlite3_errcode().
    */
    const char *zErr = (const char *)sqlite3_value_text(db->pErr); 
    sqlite3_free(v->zErrMsg);
    if( !db->mallocFailed ){
      v->zErrMsg = sqlite3DbStrDup(db, zErr);
    } else {
      v->zErrMsg = 0;
      v->rc = SQLITE_NOMEM;
    }
  }
  rc = sqlite3ApiExit(db, rc);
  sqlite3_mutex_leave(db->mutex);

  return rc;
}
#endif

/*
** Extract the user data from a sqlite3_context structure and return a
** pointer to it.

** schema change has occurred.  That detail is handled by the
** outer sqlite3_step() wrapper procedure.
*/
static int sqlite3Step(Vdbe *p){
  sqlite3 *db;
  int rc;

  assert(p);
  if( p->magic!=VDBE_MAGIC_RUN ){
    return SQLITE_MISUSE;
  }

  /* Assert that malloc() has not failed */
  db = p->db;
  assert( !db->mallocFailed );

................................................................................
/*
** This is the top-level implementation of sqlite3_step().  Call
** sqlite3Step() to do most of the work.  If a schema error occurs,
** call sqlite3Reprepare() and try again.
*/
#ifdef SQLITE_OMIT_PARSER
int sqlite3_step(sqlite3_stmt *pStmt){
  int rc = SQLITE_MISUSE;
  if( pStmt ){
    Vdbe *v;
    v = (Vdbe*)pStmt;
    sqlite3_mutex_enter(v->db->mutex);
    rc = sqlite3Step(v);
    sqlite3_mutex_leave(v->db->mutex);
  }
  return rc;
}
#else
int sqlite3_step(sqlite3_stmt *pStmt){
  int rc = SQLITE_MISUSE;
  if( pStmt ){
    int cnt = 0;

    Vdbe *v = (Vdbe*)pStmt;
    sqlite3 *db = v->db;
    sqlite3_mutex_enter(db->mutex);
    while( (rc = sqlite3Step(v))==SQLITE_SCHEMA
           && cnt++ < 5
           && sqlite3Reprepare(v) ){
      sqlite3_reset(pStmt);
      v->expired = 0;
    }
    if( rc==SQLITE_SCHEMA && v->zSql && db->pErr ){
      /* This case occurs after failing to recompile an sql statement. 
      ** The error message from the SQL compiler has already been loaded 
      ** into the database handle. This block copies the error message 
      ** from the database handle into the statement and sets the statement
      ** program counter to 0 to ensure that when the statement is 
      ** finalized or reset the parser error message is available via
      ** sqlite3_errmsg() and sqlite3_errcode().
      */
      const char *zErr = (const char *)sqlite3_value_text(db->pErr); 
      sqlite3_free(v->zErrMsg);
      if( !db->mallocFailed ){
        v->zErrMsg = sqlite3DbStrDup(db, zErr);
      } else {
        v->zErrMsg = 0;
        v->rc = SQLITE_NOMEM;
      }
    }
    rc = sqlite3ApiExit(db, rc);
    sqlite3_mutex_leave(db->mutex);
  }
  return rc;
}
#endif

/*
** Extract the user data from a sqlite3_context structure and return a
** pointer to it.