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1 import os |
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2 import sys |
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3 #import ctypes |
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4 import time |
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5 import select |
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6 import logging |
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7 |
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8 L = logging.info |
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9 W = logging.warning |
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10 E = logging.error |
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11 |
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12 DEFAULT_TRIES = 3 |
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13 READLINE_SELECT_TIMEOUT = 1 |
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14 |
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15 clock_gettime = None |
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16 no_clock_gettime = True |
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17 def monotonic_time(): |
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18 global clock_gettime |
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19 global no_clock_gettime |
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20 if no_clock_gettime: |
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21 return time.time() |
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22 |
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23 class timespec(ctypes.Structure): |
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24 _fields_ = [ |
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25 ('tv_sec', ctypes.c_long), |
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26 ('tv_nsec', ctypes.c_long) |
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27 ] |
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28 if not clock_gettime: |
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29 try: |
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30 librt = ctypes.CDLL('librt.so.0', use_errno=True) |
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31 clock_gettime = librt.clock_gettime |
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32 clock_gettime.argtypes = [ctypes.c_int, ctypes.POINTER(timespec)] |
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33 except: |
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34 W("No clock_gettime(), using fake fallback.") |
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35 no_clock_gettime = True |
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36 return time.time() |
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37 |
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38 t = timespec() |
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39 CLOCK_MONOTONIC = 1 # see <linux/time.h> |
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40 |
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41 if clock_gettime(CLOCK_MONOTONIC, ctypes.pointer(t)) != 0: |
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42 errno_ = ctypes.get_errno() |
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43 raise OSError(errno_, os.strerror(errno_)) |
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44 return t.tv_sec + t.tv_nsec * 1e-9 |
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45 |
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46 # decorator, tries a number of times, returns None on failure, sleeps between |
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47 # Must be used as "@retry()" if arguments are defaulted |
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48 def retry(retries=DEFAULT_TRIES, try_time = 1): |
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49 def inner(func): |
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50 def new_f(*args, **kwargs): |
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51 for i in range(retries): |
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52 d = func(*args, **kwargs) |
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53 if d is not None: |
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54 return d |
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55 time.sleep(try_time) |
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56 return None |
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57 |
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58 new_f.func_name = func.func_name |
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59 return new_f |
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60 return inner |
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61 |
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62 def readline(sock): |
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63 timeout = READLINE_SELECT_TIMEOUT |
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64 buf = '' |
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65 while True: |
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66 (rlist, wlist, xlist) = select.select([sock], [], [], timeout) |
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67 if sock not in rlist: |
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68 # hit timeout |
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69 return None |
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70 |
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71 c = sock.recv(1) |
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72 if c == '': |
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73 # lightblue timeout |
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74 return None |
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75 if c == '\r': |
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76 continue |
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77 |
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78 buf += c |
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79 if c == '\n': |
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80 return buf |
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81 |
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82 # from http://blog.stalkr.net/2011/04/pctf-2011-32-thats-no-bluetooth.html |
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83 def crc16(buff, crc = 0, poly = 0x8408): |
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84 l = len(buff) |
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85 i = 0 |
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86 while i < l: |
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87 ch = ord(buff[i]) |
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88 uc = 0 |
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89 while uc < 8: |
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90 if (crc & 1) ^ (ch & 1): |
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91 crc = (crc >> 1) ^ poly |
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92 else: |
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93 crc >>= 1 |
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94 ch >>= 1 |
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95 uc += 1 |
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96 i += 1 |
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97 return crc |
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98 |
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99 def cheap_daemon(): |
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100 L("Daemonising.") |
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101 sys.stdout.flush() |
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102 sys.stderr.flush() |
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103 out = file('/dev/null', 'a+') |
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104 os.dup2(out.fileno(), sys.stdout.fileno()) |
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105 os.dup2(out.fileno(), sys.stderr.fileno()) |
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106 |
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107 try: |
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108 pid = os.fork() |
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109 if pid > 0: |
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110 sys.exit(0) |
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111 except OSError, e: |
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112 E("Bad fork()") |
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113 sys.exit(1) |
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114 |
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115 os.setsid() |
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116 |
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117 try: |
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118 pid = os.fork() |
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119 if pid > 0: |
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120 sys.exit(0) |
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121 except OSError, e: |
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122 E("Bad fork()") |
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123 sys.exit(1) |
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124 |
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125 |
