236 lines
7.7 KiB
Python
236 lines
7.7 KiB
Python
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"""Extended file operations available in POSIX.
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f = posixfile.open(filename, [mode, [bufsize]])
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will create a new posixfile object
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f = posixfile.fileopen(fileobject)
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will create a posixfile object from a builtin file object
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f.file()
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will return the original builtin file object
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f.dup()
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will return a new file object based on a new filedescriptor
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f.dup2(fd)
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will return a new file object based on the given filedescriptor
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f.flags(mode)
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will turn on the associated flag (merge)
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mode can contain the following characters:
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(character representing a flag)
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a append only flag
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c close on exec flag
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n no delay flag
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s synchronization flag
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(modifiers)
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! turn flags 'off' instead of default 'on'
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= copy flags 'as is' instead of default 'merge'
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? return a string in which the characters represent the flags
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that are set
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note: - the '!' and '=' modifiers are mutually exclusive.
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- the '?' modifier will return the status of the flags after they
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have been changed by other characters in the mode string
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f.lock(mode [, len [, start [, whence]]])
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will (un)lock a region
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mode can contain the following characters:
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(character representing type of lock)
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u unlock
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r read lock
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w write lock
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(modifiers)
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| wait until the lock can be granted
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? return the first lock conflicting with the requested lock
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or 'None' if there is no conflict. The lock returned is in the
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format (mode, len, start, whence, pid) where mode is a
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character representing the type of lock ('r' or 'w')
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note: - the '?' modifier prevents a region from being locked; it is
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query only
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"""
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class _posixfile_:
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"""File wrapper class that provides extra POSIX file routines."""
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states = ['open', 'closed']
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#
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# Internal routines
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#
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def __repr__(self):
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file = self._file_
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return "<%s posixfile '%s', mode '%s' at %s>" % \
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(self.states[file.closed], file.name, file.mode, \
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hex(id(self))[2:])
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#
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# Initialization routines
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#
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def open(self, name, mode='r', bufsize=-1):
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import __builtin__
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return self.fileopen(__builtin__.open(name, mode, bufsize))
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def fileopen(self, file):
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import types
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if repr(type(file)) != "<type 'file'>":
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raise TypeError, 'posixfile.fileopen() arg must be file object'
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self._file_ = file
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# Copy basic file methods
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for maybemethod in dir(file):
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if not maybemethod.startswith('_'):
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attr = getattr(file, maybemethod)
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if isinstance(attr, types.BuiltinMethodType):
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setattr(self, maybemethod, attr)
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return self
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#
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# New methods
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#
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def file(self):
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return self._file_
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def dup(self):
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import posix
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if not hasattr(posix, 'fdopen'):
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raise AttributeError, 'dup() method unavailable'
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return posix.fdopen(posix.dup(self._file_.fileno()), self._file_.mode)
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def dup2(self, fd):
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import posix
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if not hasattr(posix, 'fdopen'):
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raise AttributeError, 'dup() method unavailable'
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posix.dup2(self._file_.fileno(), fd)
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return posix.fdopen(fd, self._file_.mode)
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def flags(self, *which):
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import fcntl, os
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if which:
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if len(which) > 1:
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raise TypeError, 'Too many arguments'
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which = which[0]
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else: which = '?'
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l_flags = 0
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if 'n' in which: l_flags = l_flags | os.O_NDELAY
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if 'a' in which: l_flags = l_flags | os.O_APPEND
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if 's' in which: l_flags = l_flags | os.O_SYNC
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file = self._file_
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if '=' not in which:
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cur_fl = fcntl.fcntl(file.fileno(), fcntl.F_GETFL, 0)
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if '!' in which: l_flags = cur_fl & ~ l_flags
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else: l_flags = cur_fl | l_flags
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l_flags = fcntl.fcntl(file.fileno(), fcntl.F_SETFL, l_flags)
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if 'c' in which:
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arg = ('!' not in which) # 0 is don't, 1 is do close on exec
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l_flags = fcntl.fcntl(file.fileno(), fcntl.F_SETFD, arg)
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if '?' in which:
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which = '' # Return current flags
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l_flags = fcntl.fcntl(file.fileno(), fcntl.F_GETFL, 0)
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if os.O_APPEND & l_flags: which = which + 'a'
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if fcntl.fcntl(file.fileno(), fcntl.F_GETFD, 0) & 1:
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which = which + 'c'
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if os.O_NDELAY & l_flags: which = which + 'n'
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if os.O_SYNC & l_flags: which = which + 's'
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return which
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def lock(self, how, *args):
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import struct, fcntl
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if 'w' in how: l_type = fcntl.F_WRLCK
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elif 'r' in how: l_type = fcntl.F_RDLCK
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elif 'u' in how: l_type = fcntl.F_UNLCK
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else: raise TypeError, 'no type of lock specified'
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if '|' in how: cmd = fcntl.F_SETLKW
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elif '?' in how: cmd = fcntl.F_GETLK
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else: cmd = fcntl.F_SETLK
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l_whence = 0
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l_start = 0
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l_len = 0
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if len(args) == 1:
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l_len = args[0]
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elif len(args) == 2:
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l_len, l_start = args
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elif len(args) == 3:
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l_len, l_start, l_whence = args
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elif len(args) > 3:
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raise TypeError, 'too many arguments'
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# Hack by davem@magnet.com to get locking to go on freebsd;
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# additions for AIX by Vladimir.Marangozov@imag.fr
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import sys, os
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if sys.platform in ('netbsd1',
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'openbsd2',
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'freebsd2', 'freebsd3', 'freebsd4', 'freebsd5',
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'freebsd6', 'freebsd7',
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'bsdos2', 'bsdos3', 'bsdos4'):
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flock = struct.pack('lxxxxlxxxxlhh', \
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l_start, l_len, os.getpid(), l_type, l_whence)
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elif sys.platform in ('aix3', 'aix4'):
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flock = struct.pack('hhlllii', \
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l_type, l_whence, l_start, l_len, 0, 0, 0)
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else:
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flock = struct.pack('hhllhh', \
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l_type, l_whence, l_start, l_len, 0, 0)
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flock = fcntl.fcntl(self._file_.fileno(), cmd, flock)
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if '?' in how:
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if sys.platform in ('netbsd1',
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'openbsd2',
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'freebsd2', 'freebsd3', 'freebsd4', 'freebsd5',
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'bsdos2', 'bsdos3', 'bsdos4'):
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l_start, l_len, l_pid, l_type, l_whence = \
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struct.unpack('lxxxxlxxxxlhh', flock)
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elif sys.platform in ('aix3', 'aix4'):
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l_type, l_whence, l_start, l_len, l_sysid, l_pid, l_vfs = \
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struct.unpack('hhlllii', flock)
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elif sys.platform == "linux2":
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l_type, l_whence, l_start, l_len, l_pid, l_sysid = \
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struct.unpack('hhllhh', flock)
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else:
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l_type, l_whence, l_start, l_len, l_sysid, l_pid = \
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struct.unpack('hhllhh', flock)
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if l_type != fcntl.F_UNLCK:
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if l_type == fcntl.F_RDLCK:
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return 'r', l_len, l_start, l_whence, l_pid
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else:
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return 'w', l_len, l_start, l_whence, l_pid
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def open(name, mode='r', bufsize=-1):
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"""Public routine to open a file as a posixfile object."""
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return _posixfile_().open(name, mode, bufsize)
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def fileopen(file):
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"""Public routine to get a posixfile object from a Python file object."""
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return _posixfile_().fileopen(file)
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#
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# Constants
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#
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SEEK_SET = 0
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SEEK_CUR = 1
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SEEK_END = 2
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#
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# End of posixfile.py
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#
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