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1 | 1 | """Posix-specific implementation of process utilities. |
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2 | 2 | |
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3 | 3 | This file is only meant to be imported by process.py, not by end-users. |
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4 | 4 | """ |
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5 | 5 | |
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6 | 6 | #----------------------------------------------------------------------------- |
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7 | 7 | # Copyright (C) 2010-2011 The IPython Development Team |
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8 | 8 | # |
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9 | 9 | # Distributed under the terms of the BSD License. The full license is in |
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10 | 10 | # the file COPYING, distributed as part of this software. |
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11 | 11 | #----------------------------------------------------------------------------- |
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12 | 12 | |
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13 | 13 | #----------------------------------------------------------------------------- |
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14 | 14 | # Imports |
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15 | 15 | #----------------------------------------------------------------------------- |
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16 | 16 | |
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17 | 17 | # Stdlib |
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18 | 18 | import errno |
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19 | 19 | import os |
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20 | 20 | import subprocess as sp |
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21 | 21 | import sys |
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22 | 22 | |
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23 | import pexpect | |
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24 | ||
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25 | 23 | # Our own |
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26 | 24 | from ._process_common import getoutput, arg_split |
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27 | 25 | from IPython.utils.encoding import DEFAULT_ENCODING |
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28 | 26 | |
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29 | 27 | #----------------------------------------------------------------------------- |
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30 | 28 | # Function definitions |
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31 | 29 | #----------------------------------------------------------------------------- |
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32 | 30 | |
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33 | 31 | class ProcessHandler(object): |
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34 | 32 | """Execute subprocesses under the control of pexpect. |
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35 | 33 | """ |
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36 | 34 | # Timeout in seconds to wait on each reading of the subprocess' output. |
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37 | 35 | # This should not be set too low to avoid cpu overusage from our side, |
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38 | 36 | # since we read in a loop whose period is controlled by this timeout. |
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39 | 37 | read_timeout = 0.05 |
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40 | 38 | |
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41 | 39 | # Timeout to give a process if we receive SIGINT, between sending the |
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42 | 40 | # SIGINT to the process and forcefully terminating it. |
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43 | 41 | terminate_timeout = 0.2 |
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44 | 42 | |
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45 | 43 | # File object where stdout and stderr of the subprocess will be written |
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46 | 44 | logfile = None |
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47 | 45 | |
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48 | 46 | # Shell to call for subprocesses to execute |
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49 | 47 | _sh = None |
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50 | 48 | |
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51 | 49 | @property |
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52 | 50 | def sh(self): |
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53 | 51 | if self._sh is None: |
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52 | import pexpect | |
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54 | 53 | shell_name = os.environ.get("SHELL", "sh") |
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55 | 54 | self._sh = pexpect.which(shell_name) |
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56 | 55 | if self._sh is None: |
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57 | 56 | raise OSError('"{}" shell not found'.format(shell_name)) |
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58 | 57 | |
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59 | 58 | return self._sh |
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60 | 59 | |
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61 | 60 | def __init__(self, logfile=None, read_timeout=None, terminate_timeout=None): |
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62 | 61 | """Arguments are used for pexpect calls.""" |
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63 | 62 | self.read_timeout = (ProcessHandler.read_timeout if read_timeout is |
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64 | 63 | None else read_timeout) |
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65 | 64 | self.terminate_timeout = (ProcessHandler.terminate_timeout if |
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66 | 65 | terminate_timeout is None else |
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67 | 66 | terminate_timeout) |
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68 | 67 | self.logfile = sys.stdout if logfile is None else logfile |
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69 | 68 | |
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70 | 69 | def getoutput(self, cmd): |
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71 | 70 | """Run a command and return its stdout/stderr as a string. |
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72 | 71 | |
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73 | 72 | Parameters |
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74 | 73 | ---------- |
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75 | 74 | cmd : str |
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76 | 75 | A command to be executed in the system shell. |
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77 | 76 | |
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78 | 77 | Returns |
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79 | 78 | ------- |
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80 | 79 | output : str |
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81 | 80 | A string containing the combination of stdout and stderr from the |
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82 | 81 | subprocess, in whatever order the subprocess originally wrote to its |
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83 | 82 | file descriptors (so the order of the information in this string is the |
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84 | 83 | correct order as would be seen if running the command in a terminal). |
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85 | 84 | """ |
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85 | import pexpect | |
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86 | 86 | try: |
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87 | 87 | return pexpect.run(self.sh, args=['-c', cmd]).replace('\r\n', '\n') |
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88 | 88 | except KeyboardInterrupt: |
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89 | 89 | print('^C', file=sys.stderr, end='') |
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90 | 90 | |
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91 | 91 | def getoutput_pexpect(self, cmd): |
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92 | 92 | """Run a command and return its stdout/stderr as a string. |
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93 | 93 | |
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94 | 94 | Parameters |
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95 | 95 | ---------- |
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96 | 96 | cmd : str |
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97 | 97 | A command to be executed in the system shell. |
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98 | 98 | |
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99 | 99 | Returns |
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100 | 100 | ------- |
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101 | 101 | output : str |
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102 | 102 | A string containing the combination of stdout and stderr from the |
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103 | 103 | subprocess, in whatever order the subprocess originally wrote to its |
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104 | 104 | file descriptors (so the order of the information in this string is the |
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105 | 105 | correct order as would be seen if running the command in a terminal). |
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106 | 106 | """ |
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107 | import pexpect | |
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107 | 108 | try: |
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108 | 109 | return pexpect.run(self.sh, args=['-c', cmd]).replace('\r\n', '\n') |
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109 | 110 | except KeyboardInterrupt: |
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110 | 111 | print('^C', file=sys.stderr, end='') |
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111 | 112 | |
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112 | 113 | def system(self, cmd): |
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113 | 114 | """Execute a command in a subshell. |
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114 | 115 | |
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115 | 116 | Parameters |
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116 | 117 | ---------- |
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117 | 118 | cmd : str |
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118 | 119 | A command to be executed in the system shell. |
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119 | 120 | |
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120 | 121 | Returns |
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121 | 122 | ------- |
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122 | 123 | int : child's exitstatus |
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123 | 124 | """ |
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125 | import pexpect | |
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126 | ||
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124 | 127 | # Get likely encoding for the output. |
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125 | 128 | enc = DEFAULT_ENCODING |
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126 | 129 | |
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127 | 130 | # Patterns to match on the output, for pexpect. We read input and |
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128 | 131 | # allow either a short timeout or EOF |
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129 | 132 | patterns = [pexpect.TIMEOUT, pexpect.EOF] |
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130 | 133 | # the index of the EOF pattern in the list. |
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131 | 134 | # even though we know it's 1, this call means we don't have to worry if |
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132 | 135 | # we change the above list, and forget to change this value: |
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133 | 136 | EOF_index = patterns.index(pexpect.EOF) |
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134 | 137 | # The size of the output stored so far in the process output buffer. |
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135 | 138 | # Since pexpect only appends to this buffer, each time we print we |
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136 | 139 | # record how far we've printed, so that next time we only print *new* |
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137 | 140 | # content from the buffer. |
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138 | 141 | out_size = 0 |
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139 | 142 | try: |
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140 | 143 | # Since we're not really searching the buffer for text patterns, we |
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141 | 144 | # can set pexpect's search window to be tiny and it won't matter. |
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142 | 145 | # We only search for the 'patterns' timeout or EOF, which aren't in |
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143 | 146 | # the text itself. |
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144 | 147 | #child = pexpect.spawn(pcmd, searchwindowsize=1) |
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145 | 148 | if hasattr(pexpect, 'spawnb'): |
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146 | 149 | child = pexpect.spawnb(self.sh, args=['-c', cmd]) # Pexpect-U |
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147 | 150 | else: |
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148 | 151 | child = pexpect.spawn(self.sh, args=['-c', cmd]) # Vanilla Pexpect |
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149 | 152 | flush = sys.stdout.flush |
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150 | 153 | while True: |
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151 | 154 | # res is the index of the pattern that caused the match, so we |
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152 | 155 | # know whether we've finished (if we matched EOF) or not |
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153 | 156 | res_idx = child.expect_list(patterns, self.read_timeout) |
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154 | 157 | print(child.before[out_size:].decode(enc, 'replace'), end='') |
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155 | 158 | flush() |
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156 | 159 | if res_idx==EOF_index: |
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157 | 160 | break |
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158 | 161 | # Update the pointer to what we've already printed |
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159 | 162 | out_size = len(child.before) |
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160 | 163 | except KeyboardInterrupt: |
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161 | 164 | # We need to send ^C to the process. The ascii code for '^C' is 3 |
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162 | 165 | # (the character is known as ETX for 'End of Text', see |
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163 | 166 | # curses.ascii.ETX). |
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164 | 167 | child.sendline(chr(3)) |
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165 | 168 | # Read and print any more output the program might produce on its |
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166 | 169 | # way out. |
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167 | 170 | try: |
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168 | 171 | out_size = len(child.before) |
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169 | 172 | child.expect_list(patterns, self.terminate_timeout) |
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170 | 173 | print(child.before[out_size:].decode(enc, 'replace'), end='') |
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171 | 174 | sys.stdout.flush() |
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172 | 175 | except KeyboardInterrupt: |
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173 | 176 | # Impatient users tend to type it multiple times |
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174 | 177 | pass |
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175 | 178 | finally: |
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176 | 179 | # Ensure the subprocess really is terminated |
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177 | 180 | child.terminate(force=True) |
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178 | 181 | # add isalive check, to ensure exitstatus is set: |
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179 | 182 | child.isalive() |
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180 | 183 | |
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181 | 184 | # We follow the subprocess pattern, returning either the exit status |
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182 | 185 | # as a positive number, or the terminating signal as a negative |
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183 | 186 | # number. |
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184 | 187 | # on Linux, sh returns 128+n for signals terminating child processes on Linux |
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185 | 188 | # on BSD (OS X), the signal code is set instead |
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186 | 189 | if child.exitstatus is None: |
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187 | 190 | # on WIFSIGNALED, pexpect sets signalstatus, leaving exitstatus=None |
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188 | 191 | if child.signalstatus is None: |
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189 | 192 | # this condition may never occur, |
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190 | 193 | # but let's be certain we always return an integer. |
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191 | 194 | return 0 |
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192 | 195 | return -child.signalstatus |
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193 | 196 | if child.exitstatus > 128: |
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194 | 197 | return -(child.exitstatus - 128) |
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195 | 198 | return child.exitstatus |
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196 | 199 | |
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197 | 200 | |
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198 | 201 | # Make system() with a functional interface for outside use. Note that we use |
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199 | 202 | # getoutput() from the _common utils, which is built on top of popen(). Using |
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200 | 203 | # pexpect to get subprocess output produces difficult to parse output, since |
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201 | 204 | # programs think they are talking to a tty and produce highly formatted output |
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202 | 205 | # (ls is a good example) that makes them hard. |
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203 | 206 | system = ProcessHandler().system |
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204 | 207 | |
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205 | 208 | def check_pid(pid): |
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206 | 209 | try: |
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207 | 210 | os.kill(pid, 0) |
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208 | 211 | except OSError as err: |
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209 | 212 | if err.errno == errno.ESRCH: |
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210 | 213 | return False |
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211 | 214 | elif err.errno == errno.EPERM: |
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212 | 215 | # Don't have permission to signal the process - probably means it exists |
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213 | 216 | return True |
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214 | 217 | raise |
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215 | 218 | else: |
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216 | 219 | return True |
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