Exporting XFS inventory in JSON format

xfsinv2json.py

#!/usr/bin/env python3

import sys # for sys.stderr
import argparse
import subprocess
import json

class Xfsinv2json:

  def parse_args(self):
    parser = argparse.ArgumentParser(formatter_class=argparse.RawTextHelpFormatter)
    parser.add_argument("-f", "--filter", type=str,
                        help="Filtering option passed to xfsdump command\n"
                            +"using result of: 'xfsdump -I FILTER'")
    parser.add_argument("-i", "--indent", type=int, default=4,
                        help="Indent width used when print JSON")
    self.args = parser.parse_args()

  def execute_xfsdump(self):
    cmd = ["xfsdump", "-I"]
    if self.args.filter: cmd.append(self.args.filter)
    self.contents =  subprocess.check_output(cmd).decode('utf-8')

  def count_indent(self, s):
    n = 0
    for c in s:
      if c != u'\t': break
      else: n += 1
    return n
    
  def create_dict_ptrs(self):
    
    def count_max_indent(s):
      m = 0
      for l in s.splitlines():
        i = self.count_indent(l)
        if m < i: m = i
      return m

    self.dict_ptrs = [ {} for i in range(count_max_indent(self.contents)+1) ]
    
  def construct_nasted_dictionary(self):

    def create_list_item(d, e):
      # "file system 0:" => name="file system", num=0
      name = " ".join(e[0].split(" ")[0:len(e[0].split(" "))-1])
      num = int(e[0].split(" ")[-1])
    
      if not name in d: d[name] = []
    
      d[name].append({})
      return d[name][-1] # type => dict

    for l in self.contents.splitlines():
      i = self.count_indent(l)
      d = self.dict_ptrs[i]
    	
      if l == "xfsdump: Dump Status: SUCCESS":
        self.success = True
        continue
    
      e = list(map(lambda x: x.strip("\t"), l.split(":")))
      if len(e) == 2 and l[-1] == ":":
        # create new list item when the line ends with ":"
        self.dict_ptrs[i+1] = create_list_item(d, e)
      else:
        d[e[0]] = ":".join(e[1:len(e)]) # value may contain ":"

  def print_json(self):
    print(json.dumps(self.dict_ptrs[0],
                     sort_keys=True,
                     indent=self.args.indent))

  def run(self):
    self.parse_args()
    self.execute_xfsdump()
    self.create_dict_ptrs()
    self.construct_nasted_dictionary()
    if self.success:
      self.print_json()
    else:
      print("Error executing xfsdump", file=sys.stderr)

if __name__ == "__main__":
  Xfsinv2json().run()