1 """Spawn a command with pipes to its stdin, stdout, and optionally stderr. 2 3 The normal os.popen(cmd, mode) call spawns a shell command and provides a 4 file interface to just the input or output of the process depending on 5 whether mode is 'r' or 'w'. This module provides the functions popen2(cmd) 6 and popen3(cmd) which return two or three pipes to the spawned command. 7 """ 8 9 import os 10 import sys 11 import warnings 12 warnings.warn("The popen2 module is deprecated. Use the subprocess module.", 13 DeprecationWarning, stacklevel=2) 14 15 __all__ = ["popen2", "popen3", "popen4"] 16 17 try: 18 MAXFD = os.sysconf('SC_OPEN_MAX') 19 except (AttributeError, ValueError): 20 MAXFD = 256 21 22 _active = [] 23 24 def _cleanup(): 25 for inst in _active[:]: 26 if inst.poll(_deadstate=sys.maxint) >= 0: 27 try: 28 _active.remove(inst) 29 except ValueError: 30 # This can happen if two threads create a new Popen instance. 31 # It's harmless that it was already removed, so ignore. 32 pass 33 34 class Popen3: 35 """Class representing a child process. Normally, instances are created 36 internally by the functions popen2() and popen3().""" 37 38 sts = -1 # Child not completed yet 39 40 def __init__(self, cmd, capturestderr=False, bufsize=-1): 41 """The parameter 'cmd' is the shell command to execute in a 42 sub-process. On UNIX, 'cmd' may be a sequence, in which case arguments 43 will be passed directly to the program without shell intervention (as 44 with os.spawnv()). If 'cmd' is a string it will be passed to the shell 45 (as with os.system()). The 'capturestderr' flag, if true, specifies 46 that the object should capture standard error output of the child 47 process. The default is false. If the 'bufsize' parameter is 48 specified, it specifies the size of the I/O buffers to/from the child 49 process.""" 50 _cleanup() 51 self.cmd = cmd 52 p2cread, p2cwrite = os.pipe() 53 c2pread, c2pwrite = os.pipe() 54 if capturestderr: 55 errout, errin = os.pipe() 56 self.pid = os.fork() 57 if self.pid == 0: 58 # Child 59 os.dup2(p2cread, 0) 60 os.dup2(c2pwrite, 1) 61 if capturestderr: 62 os.dup2(errin, 2) 63 self._run_child(cmd) 64 os.close(p2cread) 65 self.tochild = os.fdopen(p2cwrite, 'w', bufsize) 66 os.close(c2pwrite) 67 self.fromchild = os.fdopen(c2pread, 'r', bufsize) 68 if capturestderr: 69 os.close(errin) 70 self.childerr = os.fdopen(errout, 'r', bufsize) 71 else: 72 self.childerr = None 73 74 def __del__(self): 75 # In case the child hasn't been waited on, check if it's done. 76 self.poll(_deadstate=sys.maxint) 77 if self.sts < 0: 78 if _active is not None: 79 # Child is still running, keep us alive until we can wait on it. 80 _active.append(self) 81 82 def _run_child(self, cmd): 83 if isinstance(cmd, basestring): 84 cmd = ['/bin/sh', '-c', cmd] 85 os.closerange(3, MAXFD) 86 try: 87 os.execvp(cmd[0], cmd) 88 finally: 89 os._exit(1) 90 91 def poll(self, _deadstate=None): 92 """Return the exit status of the child process if it has finished, 93 or -1 if it hasn't finished yet.""" 94 if self.sts < 0: 95 try: 96 pid, sts = os.waitpid(self.pid, os.WNOHANG) 97 # pid will be 0 if self.pid hasn't terminated 98 if pid == self.pid: 99 self.sts = sts 100 except os.error: 101 if _deadstate is not None: 102 self.sts = _deadstate 103 return self.sts 104 105 def wait(self): 106 """Wait for and return the exit status of the child process.""" 107 if self.sts < 0: 108 pid, sts = os.waitpid(self.pid, 0) 109 # This used to be a test, but it is believed to be 110 # always true, so I changed it to an assertion - mvl 111 assert pid == self.pid 112 self.sts = sts 113 return self.sts 114 115 116 class Popen4(Popen3): 117 childerr = None 118 119 def __init__(self, cmd, bufsize=-1): 120 _cleanup() 121 self.cmd = cmd 122 p2cread, p2cwrite = os.pipe() 123 c2pread, c2pwrite = os.pipe() 124 self.pid = os.fork() 125 if self.pid == 0: 126 # Child 127 os.dup2(p2cread, 0) 128 os.dup2(c2pwrite, 1) 129 os.dup2(c2pwrite, 2) 130 self._run_child(cmd) 131 os.close(p2cread) 132 self.tochild = os.fdopen(p2cwrite, 'w', bufsize) 133 os.close(c2pwrite) 134 self.fromchild = os.fdopen(c2pread, 'r', bufsize) 135 136 137 if sys.platform[:3] == "win" or sys.platform == "os2emx": 138 # Some things don't make sense on non-Unix platforms. 139 del Popen3, Popen4 140 141 def popen2(cmd, bufsize=-1, mode='t'): 142 """Execute the shell command 'cmd' in a sub-process. On UNIX, 'cmd' may 143 be a sequence, in which case arguments will be passed directly to the 144 program without shell intervention (as with os.spawnv()). If 'cmd' is a 145 string it will be passed to the shell (as with os.system()). If 146 'bufsize' is specified, it sets the buffer size for the I/O pipes. The 147 file objects (child_stdout, child_stdin) are returned.""" 148 w, r = os.popen2(cmd, mode, bufsize) 149 return r, w 150 151 def popen3(cmd, bufsize=-1, mode='t'): 152 """Execute the shell command 'cmd' in a sub-process. On UNIX, 'cmd' may 153 be a sequence, in which case arguments will be passed directly to the 154 program without shell intervention (as with os.spawnv()). If 'cmd' is a 155 string it will be passed to the shell (as with os.system()). If 156 'bufsize' is specified, it sets the buffer size for the I/O pipes. The 157 file objects (child_stdout, child_stdin, child_stderr) are returned.""" 158 w, r, e = os.popen3(cmd, mode, bufsize) 159 return r, w, e 160 161 def popen4(cmd, bufsize=-1, mode='t'): 162 """Execute the shell command 'cmd' in a sub-process. On UNIX, 'cmd' may 163 be a sequence, in which case arguments will be passed directly to the 164 program without shell intervention (as with os.spawnv()). If 'cmd' is a 165 string it will be passed to the shell (as with os.system()). If 166 'bufsize' is specified, it sets the buffer size for the I/O pipes. The 167 file objects (child_stdout_stderr, child_stdin) are returned.""" 168 w, r = os.popen4(cmd, mode, bufsize) 169 return r, w 170 else: 171 def popen2(cmd, bufsize=-1, mode='t'): 172 """Execute the shell command 'cmd' in a sub-process. On UNIX, 'cmd' may 173 be a sequence, in which case arguments will be passed directly to the 174 program without shell intervention (as with os.spawnv()). If 'cmd' is a 175 string it will be passed to the shell (as with os.system()). If 176 'bufsize' is specified, it sets the buffer size for the I/O pipes. The 177 file objects (child_stdout, child_stdin) are returned.""" 178 inst = Popen3(cmd, False, bufsize) 179 return inst.fromchild, inst.tochild 180 181 def popen3(cmd, bufsize=-1, mode='t'): 182 """Execute the shell command 'cmd' in a sub-process. On UNIX, 'cmd' may 183 be a sequence, in which case arguments will be passed directly to the 184 program without shell intervention (as with os.spawnv()). If 'cmd' is a 185 string it will be passed to the shell (as with os.system()). If 186 'bufsize' is specified, it sets the buffer size for the I/O pipes. The 187 file objects (child_stdout, child_stdin, child_stderr) are returned.""" 188 inst = Popen3(cmd, True, bufsize) 189 return inst.fromchild, inst.tochild, inst.childerr 190 191 def popen4(cmd, bufsize=-1, mode='t'): 192 """Execute the shell command 'cmd' in a sub-process. On UNIX, 'cmd' may 193 be a sequence, in which case arguments will be passed directly to the 194 program without shell intervention (as with os.spawnv()). If 'cmd' is a 195 string it will be passed to the shell (as with os.system()). If 196 'bufsize' is specified, it sets the buffer size for the I/O pipes. The 197 file objects (child_stdout_stderr, child_stdin) are returned.""" 198 inst = Popen4(cmd, bufsize) 199 return inst.fromchild, inst.tochild 200 201 __all__.extend(["Popen3", "Popen4"]) 202
