mysql C API - mysql_stmt_fetch 抛出异常 : access violation write at 0x00000008

Question

我收到“node.exe 中 0x0369AF03 (libmysql.dll) 处未处理的异常:0xC0000005:访问冲突写入位置 0x00000008”。在循环中使用 mysql C API 时出现错误消息。

环境:Windows 7 32位，Mysql 5.6

这个错误只发生在Debug模式下，在release模式下，它传递并获取结果，这很奇怪。

我用谷歌搜索，并设置了 STMT_ATTR_CURSOR_TYPE，但它是相同的

请指教，谢谢!

代码:

准备声明

  static const char *sql_odb_read =
    "SELECT `type`, `size`, UNCOMPRESS(`data`) FROM GIT_ODB WHERE `repo` = ? AND `oid` = ?;";
  mysql->odb_read = mysql_stmt_init(mysql->db);
  if (mysql->odb_read == NULL)
    return GIT_ERROR;

  if (mysql_stmt_prepare(mysql->odb_read, sql_odb_read, strlen(sql_odb_read)) != 0)
    return GIT_ERROR;

  if (mysql_stmt_attr_set(mysql->odb_read, STMT_ATTR_UPDATE_MAX_LENGTH, &truth) != 0)
    return GIT_ERROR;

  if (mysql_stmt_attr_set(mysql->odb_read, STMT_ATTR_CURSOR_TYPE, (const void *)&type) != 0)
      return GIT_ERROR;

执行语句

 // bind the repo passed to the statement
  bind_buffers[0].buffer = &(backend->mysql->repo);
  bind_buffers[0].buffer_length = sizeof(backend->mysql->repo);
  bind_buffers[0].length = &bind_buffers[0].buffer_length;
  bind_buffers[0].buffer_type = MYSQL_TYPE_LONGLONG;

  // bind the oid passed to the statement
  bind_buffers[1].buffer = (void*)oid->id;
  bind_buffers[1].buffer_length = 20;
  bind_buffers[1].length = &bind_buffers[1].buffer_length;
  bind_buffers[1].buffer_type = MYSQL_TYPE_BLOB;

if (mysql_stmt_bind_param(backend->mysql->odb_read, bind_buffers) != 0)
      return GIT_ERROR;

  // execute the statement
  if (mysql_stmt_execute(backend->mysql->odb_read) != 0)
      return GIT_ERROR;

  if (mysql_stmt_num_rows(backend->mysql->odb_read) == 1) {
    result_buffers[0].buffer_type = MYSQL_TYPE_TINY;
    result_buffers[0].buffer = type_p;
    result_buffers[0].buffer_length = sizeof(type_p); //sizeof(signed char);
    result_buffers[0].is_null = 0;
    result_buffers[0].length = &type_len;
    memset(type_p, 0, sizeof(type_p));

    result_buffers[1].buffer_type = MYSQL_TYPE_LONGLONG;
    result_buffers[1].buffer = len_p;
    result_buffers[1].buffer_length = sizeof(len_p);
    result_buffers[1].is_null = 0;
    result_buffers[1].length = &len_len;
    memset(len_p, 0, sizeof(len_p));

    result_buffers[2].buffer_type = MYSQL_TYPE_LONG_BLOB;
    result_buffers[2].buffer = 0;
    result_buffers[2].is_null = 0;
    result_buffers[2].buffer_length = 0;
    result_buffers[2].length = &data_len;

    if (mysql_stmt_bind_result(backend->mysql->odb_read, result_buffers) != 0)
      return GIT_ERROR;

error = mysql_stmt_fetch(backend->mysql->odb_read);

Answer 1

我下载了libmysql符号和源文件并调试了它mysql_stmt_execute后，结果缓冲区被更改，我不知道为什么，这是libmysql bug？所以我在使用结果缓冲区之前移动了 mem_set，然后一切正常