lttng_ivc/utils/utils.py

   1 import signal
   2 import hashlib
   3 import os
   4 import time
   5 import socket
   6
   7 from lxml import etree
   8 from contextlib import closing
   9
  10
  11 def line_count(file_path):
  12     line_count = 0
  13     with open(file_path) as f:
  14         for line in f:
  15             line_count += 1
  16     return line_count
  17
  18
  19 def sha256_checksum(filename, block_size=65536):
  20     sha256 = hashlib.sha256()
  21     with open(filename, 'rb') as f:
  22         for block in iter(lambda: f.read(block_size), b''):
  23             sha256.update(block)
  24     return sha256.hexdigest()
  25
  26
  27 # TODO: timeout as a parameter or Settings
  28 # TODO: Custom exception
  29 def wait_for_file(path):
  30     i = 0
  31     timeout = 60
  32     while not os.path.exists(path):
  33         time.sleep(1)
  34         i = i + 1
  35         if i > timeout:
  36             raise Exception("File still does not exists. Timeout expired")
  37
  38
  39 # TODO: find better exception
  40 def create_empty_file(path):
  41     if os.path.exists(path):
  42         raise Exception("Path already exist")
  43     open(path, 'w').close()
  44
  45
  46 def __dummy_sigusr1_handler():
  47     pass
  48
  49
  50 def sessiond_spawn(runtime):
  51     agent_port = find_free_port()
  52     previous_handler = signal.signal(signal.SIGUSR1, __dummy_sigusr1_handler)
  53     sessiond = runtime.spawn_subprocess("lttng-sessiond -vvv -S --agent-tcp-port {}".format(agent_port))
  54     signal.sigtimedwait({signal.SIGUSR1}, 60)
  55     previous_handler = signal.signal(signal.SIGUSR1, previous_handler)
  56     return sessiond
  57
  58
  59 def find_free_port():
  60     # There is no guarantee that the port will be free at runtime but should be
  61     # good enough
  62     with closing(socket.socket(socket.AF_INET, socket.SOCK_STREAM)) as s:
  63         s.bind(('', 0))
  64         return s.getsockname()[1]
  65
  66
  67 def file_contains(file_path, list_of_string):
  68     with open(file_path, 'r') as f:
  69         for line in f:
  70             for s in list_of_string:
  71                 if s in line:
  72                     return True
  73
  74
  75 def find_dir(root, name):
  76     """
  77     Returns the absolute path or None.
  78     """
  79     abs_path = None
  80     for base, dirs, files in os.walk(root):
  81         for tmp in dirs:
  82             if tmp.endswith(name):
  83                 abs_path = os.path.abspath(os.path.join(base, tmp))
  84     return abs_path
  85
  86
  87 def xpath_query(xml_file, xpath):
  88     """
  89     Return a list of xml node corresponding to the xpath. The list can be of lenght
  90     zero.
  91     """
  92     with open(xml_file, 'r') as f:
  93         tree = etree.parse(f)
  94         root = tree.getroot()
  95         # Remove all namespace
  96         # https://stackoverflow.com/questions/18159221/remove-namespace-and-prefix-from-xml-in-python-using-lxml
  97         for elem in root.getiterator():
  98             if not hasattr(elem.tag, 'find'):
  99                 continue
 100             i = elem.tag.find('}')
 101             if i >= 0:
 102                 elem.tag = elem.tag[i+1:]
 103
 104         return root.xpath(xpath)