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bzrlib/strace.py
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# Copyright (C) 2007 Canonical Ltd
 
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# Copyright (C) 2007, 2009, 2010 Canonical Ltd
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#   Authors: Robert Collins <robert.collins@canonical.com>
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#
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# This program is free software; you can redistribute it and/or modify
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"""Support for running strace against the current process."""
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import errno
 
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from __future__ import absolute_import
 
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import os
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import signal
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import subprocess
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import tempfile
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# this is currently test-focused, so importing bzrlib.tests is ok. We might
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# want to move feature to its own module though.
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from bzrlib.tests import Feature
 
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from bzrlib import errors
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def strace(function, *args, **kwargs):
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    # capture strace output to a file
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    log_file = tempfile.NamedTemporaryFile()
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    log_file_fd = log_file.fileno()
 
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    err_file = tempfile.NamedTemporaryFile()
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    pid = os.getpid()
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    # start strace
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    strace_cmd = ['strace', '-r', '-tt', '-p', str(pid), '-o', log_file.name]
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    if follow_children:
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        strace_args.append('-f')
 
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        strace_cmd.append('-f')
 
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    # need to catch both stdout and stderr to work around
 
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    # bug 627208
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    proc = subprocess.Popen(strace_cmd,
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                            stdout=subprocess.PIPE,
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                            stderr=subprocess.STDOUT)
 
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                            stderr=err_file.fileno())
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    # Wait for strace to attach
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    attached_notice = proc.stdout.readline()
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    # Run the function to strace
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    log_file.seek(0)
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    log = log_file.read()
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    log_file.close()
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    return result, StraceResult(log)
 
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    # and stderr
 
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    err_file.seek(0)
 
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    err_messages = err_file.read()
 
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    err_file.close()
 
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    # and read any errors
 
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    if err_messages.startswith("attach: ptrace(PTRACE_ATTACH,"):
 
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        raise StraceError(err_messages=err_messages)
 
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    return result, StraceResult(log, err_messages)
 
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class StraceError(errors.BzrError):
 
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    _fmt = "strace failed: %(err_messages)s"
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class StraceResult(object):
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    """The result of stracing a function."""
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    def __init__(self, raw_log):
 
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    def __init__(self, raw_log, err_messages):
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        """Create a StraceResult.
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        :param raw_log: The output that strace created.
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        """
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        self.raw_log = raw_log
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class _StraceFeature(Feature):
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    def _probe(self):
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        try:
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            proc = subprocess.Popen(['strace'],
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                stderr=subprocess.PIPE,
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                stdout=subprocess.PIPE)
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            proc.communicate()
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            return True
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        except OSError, e:
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            if e.errno == errno.ENOENT:
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                # strace is not installed
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                return False
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            else:
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                raise
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    def feature_name(self):
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        return 'strace'
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StraceFeature = _StraceFeature()
 
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        self.err_messages = err_messages
 
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