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  • 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：

     508 typedef struct zprop_get_cbdata {
 509     int cb_sources;
 510     zfs_get_column_t cb_columns[ZFS_GET_NCOLS];
 511     int cb_colwidths[ZFS_GET_NCOLS + 1];
 512     boolean_t cb_scripted; 
 513     boolean_t cb_literal;
 514     boolean_t cb_first;
 515     zprop_list_t *cb_proplist;
 516     zfs_type_t cb_type;
 517 } 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;

     54 typedef struct callback_data {
 55     uu_avl_t        *cb_avl;
 56     int         cb_flags;
 57     zfs_type_t      cb_types;
 58     zfs_sort_column_t   *cb_sortcol;
 59     zprop_list_t        **cb_proplist;
 60     int         cb_depth_limit;
 61     int         cb_depth;
 62     uint8_t         cb_props_table[ZFS_NUM_PROPS];
 63 } 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

     1     props_list = POINTER(zprop_list_t)()
 2     props_table = (c_ubyte * ZFS_NUM_PROPS)()
 3     props_table[:] = [B_TRUE] * ZFS_NUM_PROPS
 4     
 5     props_reslist = dict()
 6     iter_data = dict()
 7     iter_data['props_list']    = props_list
 8     iter_data['props_table']   = props_table
 9     iter_data['props_reslist'] = props_reslist
10     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：

      1 def py_iter_zfs_list(zhp, arg):
  2     
  3     iter_data = arg.value
  4 
  5     props_reslist = iter_data['props_reslist']
  6     props_list    = iter_data['props_list']
  7     props_table   = iter_data['props_table']
  8     zfs_type      = iter_data['zfs_type']
  9     cur_type      = libzfs.zfs_get_type(zhp)
 10     
 11     CBFUNC        = CFUNCTYPE(c_int, c_void_p, c_void_p)
 12     iter_zfs      = CBFUNC(py_iter_zfs_list)
 13     
 14     user_props = nvlist_p()
 15 
 16     if cur_type & zfs_type:
 17         libzfs.zfs_prune_proplist(zhp, props_table)
 18         libzfs.zfs_expand_proplist(zhp, byref(props_list), 0, 0)
 19         
 20         prop = create_string_buffer(ZFS_MAXPROPLEN)
 21         strval = c_char_p()
 22         userprops = libzfs.zfs_get_user_props(zhp)
 23         propval = nvlist_p()
 24         sourcetype = c_int()
 25         libzfs.zfs_prop_to_name.restype = c_char_p
 26         
 27         while props_list:
 28             pn = props_list.contents
 29             propname  = '-' 
 30             propstr = '-'
 31             
 32             if pn.pl_prop != ZPROP_INVAL:
 33                 if libzfs.zfs_prop_get(zhp, pn.pl_prop, prop, 
 34                         ZFS_MAXPROPLEN, 0, 0, 0, B_FALSE) != 0:
 35                     if pn.pl_all :
 36                         props_list = cast(pn.pl_next, POINTER(zprop_list_t))
 37                         continue
 38                     if libzfs.zfs_prop_valid_for_type(pn.pl_prop, 
 39                             ZFS_TYPE_VOLUME) :
 40                         props_list = cast(pn.pl_next, POINTER(zprop_list_t))
 41                         continue
 42                     propstr = '-'
 43                 else:
 44                     propstr = prop.value.decode()
 45                 propname = libzfs.zfs_prop_to_name(pn.pl_prop).decode()
 46             elif libzfs.zfs_prop_userquota(pn.pl_user_prop) :
 47                 if libzfs.zfs_prop_get_userquota(zhp, pn.pl_user_prop, 
 48                         prop, ZFS_MAXPROPLEN, B_FALSE) == 0:
 49                     propstr = prop.value.decode()
 50                 else:
 51                     propstr = '-'
 52                 propname = pn.pl_user_prop.decode()
 53             elif libzfs.zfs_prop_written(pn.pl_user_prop) :
 54                 if libzfs.zfs_prop_get_written(zhp, pn.pl_user_prop, 
 55                         prop, ZFS_MAXPROPLEN, B_FALSE) == 0:
 56                     propstr = prop.value.decode()
 57                 else:
 58                     propstr = '-'
 59                 propname = pn.pl_user_prop.decode()
 60             else:
 61                 if lbnvpair.nvlist_lookup_nvlist(user_props, pn.pl_user_prop, 
 62                         byref(propval)) != 0 :
 63                     if pn.pl_all :
 64                         props_list = cast(pn.pl_next, POINTER(zprop_list_t))
 65                         continue
 66                     propstr = '-'
 67                 else :
 68                     lbnvpair.nvlist_lookup_string(propval, 
 69                             ZPROP_VALUE, byref(strval))
 70                     propstr = strval.value.decode()
 71                 propname = pn.pl_user_prop.decode()
 72             props_reslist.update({propname:propstr})
 73             props_list = cast(pn.pl_next, POINTER(zprop_list_t))
 74     
 75     libzfs.zfs_close(zhp)
 76     return 0
 77 
 78 def zvol_get_all_props(name):
 79     ret = [0, '']
 80     props_list = POINTER(zprop_list_t)()
 81     props_table = (c_ubyte * ZFS_NUM_PROPS)()
 82     props_table[:] = [B_TRUE] * ZFS_NUM_PROPS
 83     
 84     props_reslist = dict()
 85     iter_data = dict()
 86     iter_data['props_list']    = props_list
 87     iter_data['props_table']   = props_table
 88     iter_data['props_reslist'] = props_reslist
 89     iter_data['zfs_type']      = ZFS_TYPE_VOLUME
 90     
 91     g_zfs = libzfs.libzfs_init()
 92     libzfs.libzfs_error_description.restype = c_char_p
 93 
 94     zhp = libzfs.zfs_path_to_zhandle(g_zfs, 
 95             bytes(name, encoding='ascii'), ZFS_TYPE_VOLUME)
 96     
 97     if not zhp:
 98         ret[0] = libzfs.libzfs_errno(g_zfs)
 99         ret[1] = libzfs.libzfs_error_description(g_zfs).decode()
100         return None
101 
102     libzfs.zprop_free_list(iter_data['props_list'])
103     py_iter_zfs_list(zhp, py_object(iter_data))
104     
105     libzfs.libzfs_fini(g_zfs)
106     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
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  • 原文地址：https://www.cnblogs.com/fendou-999/p/3831352.html
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