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|
#
# Start of posixfile.py
#
#
# Extended file operations
#
# 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
#
class _posixfile_:
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:])
def __del__(self):
self._file_.close()
#
# Initialization routines
#
def open(self, name, mode='r', bufsize=-1):
import __builtin__
return self.fileopen(__builtin__.open(name, mode, bufsize))
def fileopen(self, file):
if `type(file)` != "<type 'file'>":
raise TypeError, 'posixfile.fileopen() arg must be file object'
self._file_ = file
# Copy basic file methods
for method in file.__methods__:
setattr(self, method, getattr(file, method))
return self
#
# New methods
#
def file(self):
return self._file_
def dup(self):
import posix
try: ignore = posix.fdopen
except: raise AttributeError, 'dup() method unavailable'
return posix.fdopen(posix.dup(self._file_.fileno()), self._file_.mode)
def dup2(self, fd):
import posix
try: ignore = posix.fdopen
except: raise AttributeError, 'dup() method unavailable'
posix.dup2(self._file_.fileno(), fd)
return posix.fdopen(fd, self._file_.mode)
def flags(self, *which):
import fcntl, FCNTL
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 | FCNTL.O_NDELAY
if 'a' in which: l_flags = l_flags | FCNTL.O_APPEND
if 's' in which: l_flags = l_flags | FCNTL.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 FCNTL.O_APPEND & l_flags: which = which + 'a'
if fcntl.fcntl(file.fileno(), FCNTL.F_GETFD, 0) & 1:
which = which + 'c'
if FCNTL.O_NDELAY & l_flags: which = which + 'n'
if FCNTL.O_SYNC & l_flags: which = which + 's'
return which
def lock(self, how, *args):
import struct, fcntl, 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
import sys, os
if sys.platform == 'freebsd2':
flock = struct.pack('lxxxxlxxxxlhh', \
l_start, l_len, os.getpid(), l_type, l_whence)
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 == 'freebsd2':
l_start, l_len, l_pid, l_type, l_whence = \
struct.unpack('lxxxxlxxxxlhh', 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
#
# Public routine to obtain a posixfile object
#
def open(name, mode='r', bufsize=-1):
return _posixfile_().open(name, mode, bufsize)
def fileopen(file):
return _posixfile_().fileopen(file)
#
# Constants
#
SEEK_SET = 0
SEEK_CUR = 1
SEEK_END = 2
#
# End of posixfile.py
#
|
