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https://github.com/python/cpython.git
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54f22ed30b
who writes: Here is batch 2, as a big collection of CVS context diffs. Along with moving comments into docstrings, i've added a couple of missing docstrings and attempted to make sure more module docstrings begin with a one-line summary. I did not add docstrings to the methods in profile.py for fear of upsetting any careful optimizations there, though i did move class documentation into class docstrings. The convention i'm using is to leave credits/version/copyright type of stuff in # comments, and move the rest of the descriptive stuff about module usage into module docstrings. Hope this is okay.
128 lines
4.1 KiB
Python
128 lines
4.1 KiB
Python
"""Spawn a command with pipes to its stdin, stdout, and optionally stderr.
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The normal os.popen(cmd, mode) call spawns a shell command and provides a
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file interface to just the input or output of the process depending on
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whether mode is 'r' or 'w'. This module provides the functions popen2(cmd)
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and popen3(cmd) which return two or three pipes to the spawned command.
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"""
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import os
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import sys
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import string
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MAXFD = 256 # Max number of file descriptors (os.getdtablesize()???)
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_active = []
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def _cleanup():
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for inst in _active[:]:
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inst.poll()
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class Popen3:
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"""Class representing a child process. Normally instances are created
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by the factory functions popen2() and popen3()."""
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def __init__(self, cmd, capturestderr=0, bufsize=-1):
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"""The parameter 'cmd' is the shell command to execute in a
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sub-process. The 'capturestderr' flag, if true, specifies that
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the object should capture standard error output of the child process.
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The default is false. If the 'bufsize' parameter is specified, it
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specifies the size of the I/O buffers to/from the child process."""
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if type(cmd) == type(''):
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cmd = ['/bin/sh', '-c', cmd]
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p2cread, p2cwrite = os.pipe()
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c2pread, c2pwrite = os.pipe()
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if capturestderr:
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errout, errin = os.pipe()
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self.pid = os.fork()
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if self.pid == 0:
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# Child
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os.close(0)
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os.close(1)
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if os.dup(p2cread) <> 0:
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sys.stderr.write('popen2: bad read dup\n')
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if os.dup(c2pwrite) <> 1:
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sys.stderr.write('popen2: bad write dup\n')
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if capturestderr:
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os.close(2)
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if os.dup(errin) <> 2: pass
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for i in range(3, MAXFD):
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try:
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os.close(i)
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except: pass
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try:
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os.execvp(cmd[0], cmd)
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finally:
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os._exit(1)
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# Shouldn't come here, I guess
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os._exit(1)
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os.close(p2cread)
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self.tochild = os.fdopen(p2cwrite, 'w', bufsize)
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os.close(c2pwrite)
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self.fromchild = os.fdopen(c2pread, 'r', bufsize)
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if capturestderr:
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os.close(errin)
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self.childerr = os.fdopen(errout, 'r', bufsize)
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else:
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self.childerr = None
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self.sts = -1 # Child not completed yet
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_active.append(self)
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def poll(self):
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"""Return the exit status of the child process if it has finished,
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or -1 if it hasn't finished yet."""
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if self.sts < 0:
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try:
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pid, sts = os.waitpid(self.pid, os.WNOHANG)
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if pid == self.pid:
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self.sts = sts
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_active.remove(self)
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except os.error:
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pass
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return self.sts
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def wait(self):
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"""Wait for and return the exit status of the child process."""
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pid, sts = os.waitpid(self.pid, 0)
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if pid == self.pid:
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self.sts = sts
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_active.remove(self)
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return self.sts
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def popen2(cmd, bufsize=-1):
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"""Execute the shell command 'cmd' in a sub-process. If 'bufsize' is
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specified, it sets the buffer size for the I/O pipes. The file objects
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(child_stdout, child_stdin) are returned."""
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_cleanup()
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inst = Popen3(cmd, 0, bufsize)
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return inst.fromchild, inst.tochild
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def popen3(cmd, bufsize=-1):
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"""Execute the shell command 'cmd' in a sub-process. If 'bufsize' is
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specified, it sets the buffer size for the I/O pipes. The file objects
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(child_stdout, child_stdin, child_stderr) are returned."""
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_cleanup()
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inst = Popen3(cmd, 1, bufsize)
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return inst.fromchild, inst.tochild, inst.childerr
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def _test():
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teststr = "abc\n"
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print "testing popen2..."
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r, w = popen2('cat')
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w.write(teststr)
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w.close()
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assert r.read() == teststr
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print "testing popen3..."
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r, w, e = popen3(['cat'])
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w.write(teststr)
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w.close()
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assert r.read() == teststr
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assert e.read() == ""
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for inst in _active[:]:
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inst.wait()
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assert not _active
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print "All OK"
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if __name__ == '__main__':
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_test()
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