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Edit File: posixfile.py

"""Extended file operations available in POSIX. f = posixfile.open(filename, [mode, [bufsize]]) will create a new posixfile object f = posixfile.fileopen(fileobject) will create a posixfile object from a builtin file object f.file() will return the original builtin file object f.dup() will return a new file object based on a new filedescriptor f.dup2(fd) will return a new file object based on the given filedescriptor f.flags(mode) will turn on the associated flag (merge) mode can contain the following characters: (character representing a flag) a append only flag c close on exec flag n no delay flag s synchronization flag (modifiers) ! turn flags 'off' instead of default 'on' = copy flags 'as is' instead of default 'merge' ? return a string in which the characters represent the flags that are set note: - the '!' and '=' modifiers are mutually exclusive. - the '?' modifier will return the status of the flags after they have been changed by other characters in the mode string f.lock(mode [, len [, start [, whence]]]) will (un)lock a region mode can contain the following characters: (character representing type of lock) u unlock r read lock w write lock (modifiers) | wait until the lock can be granted ? return the first lock conflicting with the requested lock or 'None' if there is no conflict. The lock returned is in the format (mode, len, start, whence, pid) where mode is a character representing the type of lock ('r' or 'w') note: - the '?' modifier prevents a region from being locked; it is query only """ import warnings warnings.warn("The posixfile module is deprecated; " "fcntl.lockf() provides better locking", DeprecationWarning, 2) class _posixfile_: """File wrapper class that provides extra POSIX file routines.""" states = ['open', 'closed'] # # Internal routines # def __repr__(self): file = self._file_ return "<%s posixfile '%s', mode '%s' at %s>" % \ (self.states[file.closed], file.name, file.mode, \ hex(id(self))[2:]) # # Initialization routines # def open(self, name, mode='r', bufsize=-1): import __builtin__ return self.fileopen(__builtin__.open(name, mode, bufsize)) def fileopen(self, file): import types if repr(type(file)) != "<type 'file'>": raise TypeError, 'posixfile.fileopen() arg must be file object' self._file_ = file # Copy basic file methods for maybemethod in dir(file): if not maybemethod.startswith('_'): attr = getattr(file, maybemethod) if isinstance(attr, types.BuiltinMethodType): setattr(self, maybemethod, attr) return self # # New methods # def file(self): return self._file_ def dup(self): import posix if not hasattr(posix, 'fdopen'): raise AttributeError, 'dup() method unavailable' return posix.fdopen(posix.dup(self._file_.fileno()), self._file_.mode) def dup2(self, fd): import posix if not hasattr(posix, 'fdopen'): raise AttributeError, 'dup() method unavailable' posix.dup2(self._file_.fileno(), fd) return posix.fdopen(fd, self._file_.mode) def flags(self, *which): import fcntl, os if which: if len(which) > 1: raise TypeError, 'Too many arguments' which = which[0] else: which = '?' l_flags = 0 if 'n' in which: l_flags = l_flags | os.O_NDELAY if 'a' in which: l_flags = l_flags | os.O_APPEND if 's' in which: l_flags = l_flags | os.O_SYNC file = self._file_ if '=' not in which: cur_fl = fcntl.fcntl(file.fileno(), fcntl.F_GETFL, 0) if '!' in which: l_flags = cur_fl & ~ l_flags else: l_flags = cur_fl | l_flags l_flags = fcntl.fcntl(file.fileno(), fcntl.F_SETFL, l_flags) if 'c' in which: arg = ('!' not in which) # 0 is don't, 1 is do close on exec l_flags = fcntl.fcntl(file.fileno(), fcntl.F_SETFD, arg) if '?' in which: which = '' # Return current flags l_flags = fcntl.fcntl(file.fileno(), fcntl.F_GETFL, 0) if os.O_APPEND & l_flags: which = which + 'a' if fcntl.fcntl(file.fileno(), fcntl.F_GETFD, 0) & 1: which = which + 'c' if os.O_NDELAY & l_flags: which = which + 'n' if os.O_SYNC & l_flags: which = which + 's' return which def lock(self, how, *args): import struct, fcntl if 'w' in how: l_type = fcntl.F_WRLCK elif 'r' in how: l_type = fcntl.F_RDLCK elif 'u' in how: l_type = fcntl.F_UNLCK else: raise TypeError, 'no type of lock specified' if '|' in how: cmd = fcntl.F_SETLKW elif '?' in how: cmd = fcntl.F_GETLK else: cmd = fcntl.F_SETLK l_whence = 0 l_start = 0 l_len = 0 if len(args) == 1: l_len = args[0] elif len(args) == 2: l_len, l_start = args elif len(args) == 3: l_len, l_start, l_whence = args elif len(args) > 3: raise TypeError, 'too many arguments' # Hack by davem@magnet.com to get locking to go on freebsd; # additions for AIX by Vladimir.Marangozov@imag.fr import sys, os if sys.platform in ('netbsd1', 'openbsd2', 'freebsd2', 'freebsd3', 'freebsd4', 'freebsd5', 'freebsd6', 'freebsd7', 'freebsd8', 'bsdos2', 'bsdos3', 'bsdos4'): flock = struct.pack('lxxxxlxxxxlhh', \ l_start, l_len, os.getpid(), l_type, l_whence) elif sys.platform in ('aix3', 'aix4'): flock = struct.pack('hhlllii', \ l_type, l_whence, l_start, l_len, 0, 0, 0) else: flock = struct.pack('hhllhh', \ l_type, l_whence, l_start, l_len, 0, 0) flock = fcntl.fcntl(self._file_.fileno(), cmd, flock) if '?' in how: if sys.platform in ('netbsd1', 'openbsd2', 'freebsd2', 'freebsd3', 'freebsd4', 'freebsd5', 'bsdos2', 'bsdos3', 'bsdos4'): l_start, l_len, l_pid, l_type, l_whence = \ struct.unpack('lxxxxlxxxxlhh', flock) elif sys.platform in ('aix3', 'aix4'): l_type, l_whence, l_start, l_len, l_sysid, l_pid, l_vfs = \ struct.unpack('hhlllii', flock) elif sys.platform == "linux2": l_type, l_whence, l_start, l_len, l_pid, l_sysid = \ struct.unpack('hhllhh', flock) else: l_type, l_whence, l_start, l_len, l_sysid, l_pid = \ struct.unpack('hhllhh', flock) if l_type != fcntl.F_UNLCK: if l_type == fcntl.F_RDLCK: return 'r', l_len, l_start, l_whence, l_pid else: return 'w', l_len, l_start, l_whence, l_pid def open(name, mode='r', bufsize=-1): """Public routine to open a file as a posixfile object.""" return _posixfile_().open(name, mode, bufsize) def fileopen(file): """Public routine to get a posixfile object from a Python file object.""" return _posixfile_().fileopen(file) # # Constants # SEEK_SET = 0 SEEK_CUR = 1 SEEK_END = 2 # # End of posixfile.py #