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|
"""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
"""
__all__ = ["open","fileopen","SEEK_SET","SEEK_CUR","SEEK_END"]
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):
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;
# additions for AIX by Vladimir.Marangozov@imag.fr
import sys, os
if sys.platform in ('netbsd1',
'openbsd2',
'freebsd2', 'freebsd3', 'freebsd4', 'freebsd5',
'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
#
|
