src/nepi/util/environ.py

   1 # vim:ts=4:sw=4:et:ai:sts=4
   2
   3 import os, subprocess, os.path
   4
   5 __all__ =  ["python", "ssh_path"]
   6 __all__ += ["rsh", "tcpdump_path", "sshd_path"]
   7 __all__ += ["execute", "backticks"]
   8
   9 def find_bin(name, extra_path = None):
  10     search = []
  11     if "PATH" in os.environ:
  12         search += os.environ["PATH"].split(":")
  13     for pref in ("/", "/usr/", "/usr/local/"):
  14         for d in ("bin", "sbin"):
  15             search.append(pref + d)
  16     if extra_path:
  17         search += extra_path
  18
  19     for d in search:
  20             try:
  21                 os.stat(d + "/" + name)
  22                 return d + "/" + name
  23             except OSError, e:
  24                 if e.errno != os.errno.ENOENT:
  25                     raise
  26     return None
  27
  28 def find_bin_or_die(name, extra_path = None):
  29     r = find_bin(name)
  30     if not r:
  31         raise RuntimeError(("Cannot find `%s' command, impossible to " +
  32                 "continue.") % name)
  33     return r
  34
  35 ssh_path = find_bin_or_die("ssh")
  36 python_path = find_bin_or_die("python")
  37
  38 # Optional tools
  39 rsh_path = find_bin("rsh")
  40 tcpdump_path = find_bin("tcpdump")
  41 sshd_path = find_bin("sshd")
  42
  43 def execute(cmd):
  44     # FIXME: create a global debug variable
  45     #print "[pid %d]" % os.getpid(), " ".join(cmd)
  46     null = open("/dev/null", "r+")
  47     p = subprocess.Popen(cmd, stdout = null, stderr = subprocess.PIPE)
  48     out, err = p.communicate()
  49     if p.returncode != 0:
  50         raise RuntimeError("Error executing `%s': %s" % (" ".join(cmd), err))
  51
  52 def backticks(cmd):
  53     p = subprocess.Popen(cmd, stdout = subprocess.PIPE,
  54             stderr = subprocess.PIPE)
  55     out, err = p.communicate()
  56     if p.returncode != 0:
  57         raise RuntimeError("Error executing `%s': %s" % (" ".join(cmd), err))
  58     return out
  59
  60 def homepath(path, app='.nepi', mode = 0500, directory = False):
  61     home = os.environ.get('HOME')
  62     if home is None:
  63         home = os.path.join(os.sep, 'home', os.getlogin())
  64
  65     path = os.path.join(home, app, path)
  66     if directory:
  67         dirname = path
  68     else:
  69         dirname = os.path.dirname(path)
  70     if not os.path.exists(dirname):
  71         os.makedirs(dirname)
  72
  73     return path
  74
  75 def find_testbed(testbed_id):
  76     mod_name = None
  77
  78     # look for environment-specified testbeds
  79     if 'NEPI_TESTBEDS' in os.environ:
  80         try:
  81             # parse testbed map
  82             #   split space-separated items, filter empty items
  83             testbed_map = filter(bool,os.environ['NEPI_TESTBEDS'].strip().split(' '))
  84             #   split items, keep pairs only, build map
  85             testbed_map = dict([map(str.strip,i.split(':',1)) for i in testbed_map if ':' in i])
  86         except:
  87             import traceback, sys
  88             traceback.print_exc(file=sys.stderr)
  89
  90             # ignore malformed environment
  91             testbed_map = {}
  92
  93         mod_name = testbed_map.get(testbed_id)
  94
  95     if mod_name is None:
  96         # no explicit map, load built-in testbeds
  97         mod_name = "nepi.testbeds.%s" % (testbed_id.lower())
  98
  99     return mod_name
 100