项目记录 -- zfs get all [volume] python实现的数据构造

zfs get all [volume]命令实现中构造数据结构

一、zfs get all [volume]命令源代码C实现中用到的数据结构有zprop_get_cbdata 和 callback_data，如下所示：

  typedef struct zprop_get_cbdata {
      int cb_sources;
      zfs_get_column_t cb_columns[ZFS_GET_NCOLS];
      int cb_colwidths[ZFS_GET_NCOLS + ];
      boolean_t cb_scripted;
      boolean_t cb_literal;
      boolean_t cb_first;
      zprop_list_t *cb_proplist;
      zfs_type_t cb_type;
  } zprop_get_cbdata_t; 

zprop_get_cbdata结构中主要用到的部分为zprop_list_t *cb_proplist;zfs_type_t cb_type;

  typedef struct callback_data {
      uu_avl_t        *cb_avl;
      int         cb_flags;
      zfs_type_t      cb_types;
      zfs_sort_column_t   *cb_sortcol;
      zprop_list_t        **cb_proplist;
      int         cb_depth_limit;
      int         cb_depth;
      uint8_t         cb_props_table[ZFS_NUM_PROPS];
  } callback_data_t;  

callback_data结构中主要用到的部分为cb_props_table[ZFS_NUM_PROPS]

二、设计的python数据结构

     props_list = POINTER(zprop_list_t)()
     props_table = (c_ubyte * ZFS_NUM_PROPS)()
     props_table[:] = [B_TRUE] * ZFS_NUM_PROPS

     props_reslist = dict()
     iter_data = dict()
     iter_data['props_list']    = props_list
     iter_data['props_table']   = props_table
     iter_data['props_reslist'] = props_reslist
     iter_data['zfs_type']      = ZFS_TYPE_VOLUME

iter_data为构造的python数据结构，说明如下：

1.props_table = (c_ubyte * ZFS_NUM_PROPS)()  -- 类型定义

props_table[:] = [B_TRUE] * ZFS_NUM_PROPS  -- 初始化

iter_data['props_table'] = props_table

以上对应的为：uint8_t cb_props_table[ZFS_NUM_PROPS];

2. iter_data['zfs_type'] = ZFS_TYPE_VOLUME

以上对应的为：zfs_type_t cb_type;

3. props_list = POINTER(zprop_list_t)()

iter_data['props_list'] = props_list

以上对应的为：zprop_list_t *cb_proplist;

4.iter_data['props_reslist'] = props_reslist

用于存放数据（dict 属性值），用作返回

三、整体代码如下：

 def py_iter_zfs_list(zhp, arg):

     iter_data = arg.value

     props_reslist = iter_data['props_reslist']
     props_list    = iter_data['props_list']
     props_table   = iter_data['props_table']
     zfs_type      = iter_data['zfs_type']
     cur_type      = libzfs.zfs_get_type(zhp)

     CBFUNC        = CFUNCTYPE(c_int, c_void_p, c_void_p)
     iter_zfs      = CBFUNC(py_iter_zfs_list)

     user_props = nvlist_p()

     if cur_type & zfs_type:
         libzfs.zfs_prune_proplist(zhp, props_table)
         libzfs.zfs_expand_proplist(zhp, byref(props_list), 0, 0)

         prop = create_string_buffer(ZFS_MAXPROPLEN)
         strval = c_char_p()
         userprops = libzfs.zfs_get_user_props(zhp)
         propval = nvlist_p()
         sourcetype = c_int()
         libzfs.zfs_prop_to_name.restype = c_char_p

         while props_list:
             pn = props_list.contents
             propname  = '-'
             propstr = '-'

             if pn.pl_prop != ZPROP_INVAL:
                 if libzfs.zfs_prop_get(zhp, pn.pl_prop, prop, \
                         ZFS_MAXPROPLEN, 0, 0, 0, B_FALSE) != 0:
                     if pn.pl_all :
                         props_list = cast(pn.pl_next, POINTER(zprop_list_t))
                         continue
                     if libzfs.zfs_prop_valid_for_type(pn.pl_prop, \
                             ZFS_TYPE_VOLUME) :
                         props_list = cast(pn.pl_next, POINTER(zprop_list_t))
                         continue
                     propstr = '-'
                 else:
                     propstr = prop.value.decode()
                 propname = libzfs.zfs_prop_to_name(pn.pl_prop).decode()
             elif libzfs.zfs_prop_userquota(pn.pl_user_prop) :
                 if libzfs.zfs_prop_get_userquota(zhp, pn.pl_user_prop, \
                         prop, ZFS_MAXPROPLEN, B_FALSE) == 0:
                     propstr = prop.value.decode()
                 else:
                     propstr = '-'
                 propname = pn.pl_user_prop.decode()
             elif libzfs.zfs_prop_written(pn.pl_user_prop) :
                 if libzfs.zfs_prop_get_written(zhp, pn.pl_user_prop, \
                         prop, ZFS_MAXPROPLEN, B_FALSE) == 0:
                     propstr = prop.value.decode()
                 else:
                     propstr = '-'
                 propname = pn.pl_user_prop.decode()
             else:
                 if lbnvpair.nvlist_lookup_nvlist(user_props, pn.pl_user_prop, \
                         byref(propval)) != 0 :
                     if pn.pl_all :
                         props_list = cast(pn.pl_next, POINTER(zprop_list_t))
                         continue
                     propstr = '-'
                 else :
                     lbnvpair.nvlist_lookup_string(propval, \
                             ZPROP_VALUE, byref(strval))
                     propstr = strval.value.decode()
                 propname = pn.pl_user_prop.decode()
             props_reslist.update({propname:propstr})
             props_list = cast(pn.pl_next, POINTER(zprop_list_t))

     libzfs.zfs_close(zhp)
     return 0

 def zvol_get_all_props(name):
     ret = [0, '']
     props_list = POINTER(zprop_list_t)()
     props_table = (c_ubyte * ZFS_NUM_PROPS)()
     props_table[:] = [B_TRUE] * ZFS_NUM_PROPS

     props_reslist = dict()
     iter_data = dict()
     iter_data['props_list']    = props_list
     iter_data['props_table']   = props_table
     iter_data['props_reslist'] = props_reslist
     iter_data['zfs_type']      = ZFS_TYPE_VOLUME

     g_zfs = libzfs.libzfs_init()
     libzfs.libzfs_error_description.restype = c_char_p

     zhp = libzfs.zfs_path_to_zhandle(g_zfs, \
             bytes(name, encoding='ascii'), ZFS_TYPE_VOLUME)

     if not zhp:
         ret[0] = libzfs.libzfs_errno(g_zfs)
         ret[1] = libzfs.libzfs_error_description(g_zfs).decode()
         return None

     libzfs.zprop_free_list(iter_data['props_list'])
     py_iter_zfs_list(zhp, py_object(iter_data))

     libzfs.libzfs_fini(g_zfs)
     return props_reslist

代码说明：

1.构造数据调用的方法：

py_iter_zfs_list(zhp, py_object(iter_data))

def py_iter_zfs_list(zhp, arg):

　　iter_data = arg.value