161 lines
5.2 KiB
Python
161 lines
5.2 KiB
Python
import subprocess
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import os
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import select
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try:
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from shlex import quote as cmd_quote
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except ImportError:
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from pipes import quote as cmd_quote
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class CmdItem:
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"""one command item, to be added to a CmdPipe"""
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def __init__(self, cmd, readonly=False, stderr_handler=None, exit_handler=None, shell=False):
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"""create item. caller has to make sure cmd is properly escaped when using shell.
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:type cmd: list of str
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"""
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self.cmd = cmd
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self.readonly = readonly
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self.stderr_handler = stderr_handler
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self.exit_handler = exit_handler
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self.shell = shell
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self.process = None
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def __str__(self):
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"""return copy-pastable version of command."""
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if self.shell:
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# its already copy pastable for a shell:
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return " ".join(self.cmd)
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else:
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# make it copy-pastable, will make a mess of quotes sometimes, but is correct
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return " ".join(map(cmd_quote, self.cmd))
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def create(self, stdin):
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"""actually create the subprocess (called by CmdPipe)"""
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# make sure the command gets all the data in utf8 format:
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# (this is necessary if LC_ALL=en_US.utf8 is not set in the environment)
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encoded_cmd = []
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for arg in self.cmd:
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encoded_cmd.append(arg.encode('utf-8'))
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self.process = subprocess.Popen(encoded_cmd, env=os.environ, stdout=subprocess.PIPE, stdin=stdin,
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stderr=subprocess.PIPE, shell=self.shell)
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class CmdPipe:
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"""a pipe of one or more commands. also takes care of utf-8 encoding/decoding and line based parsing"""
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def __init__(self, readonly=False, inp=None):
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"""
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:param inp: input string for stdin
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:param readonly: Only execute if entire pipe consist of readonly commands
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"""
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# list of commands + error handlers to execute
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self.items = []
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self.inp = inp
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self.readonly = readonly
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self._should_execute = True
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def add(self, cmd_item):
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"""adds a CmdItem to pipe.
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:type cmd_item: CmdItem
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"""
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self.items.append(cmd_item)
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if not cmd_item.readonly and self.readonly:
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self._should_execute = False
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def __str__(self):
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"""transform whole pipe into oneliner for debugging and testing. this should generate a copy-pastable string for in a console """
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ret = ""
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for item in self.items:
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if ret:
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ret = ret + " | "
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ret = ret + "({})".format(item) # this will do proper escaping to make it copypastable
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return ret
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def should_execute(self):
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return self._should_execute
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def execute(self, stdout_handler):
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"""run the pipe. returns True all exit handlers returned true"""
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if not self._should_execute:
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return True
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# first process should have actual user input as stdin:
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selectors = []
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# create processes
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last_stdout = None
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stdin = subprocess.PIPE
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for item in self.items:
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item.create(stdin)
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selectors.append(item.process.stderr)
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if last_stdout is None:
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# we're the first process in the pipe, do we have some input?
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if self.inp is not None:
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# TODO: make streaming to support big inputs?
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item.process.stdin.write(self.inp.encode('utf-8'))
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item.process.stdin.close()
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else:
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# last stdout was piped to this stdin already, so close it because we dont need it anymore
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last_stdout.close()
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last_stdout = item.process.stdout
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stdin = last_stdout
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# monitor last stdout as well
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selectors.append(last_stdout)
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while True:
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# wait for output on one of the stderrs or last_stdout
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(read_ready, write_ready, ex_ready) = select.select(selectors, [], [])
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eof_count = 0
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done_count = 0
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# read line and call appropriate handlers
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if last_stdout in read_ready:
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line = last_stdout.readline().decode('utf-8').rstrip()
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if line != "":
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stdout_handler(line)
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else:
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eof_count = eof_count + 1
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for item in self.items:
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if item.process.stderr in read_ready:
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line = item.process.stderr.readline().decode('utf-8').rstrip()
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if line != "":
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item.stderr_handler(line)
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else:
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eof_count = eof_count + 1
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if item.process.poll() is not None:
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done_count = done_count + 1
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# all filehandles are eof and all processes are done (poll() is not None)
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if eof_count == len(selectors) and done_count == len(self.items):
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break
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# close filehandles
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last_stdout.close()
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for item in self.items:
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item.process.stderr.close()
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# call exit handlers
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success = True
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for item in self.items:
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if item.exit_handler is not None:
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success=item.exit_handler(item.process.returncode) and success
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return success
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