New module by Jaap V

Lib/posixfile.py

@@ -0,0 +1,178 @@
+#
+# Start of posixfile.py
+#
+
+#
+# Extended file operations
+#
+# f = posixfile.open(filename, mode)
+#
+# 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_:
+    #
+    # Internal routines
+    #
+    def __repr__(self):
+	return repr(self._file_)
+
+    def __del__(self):
+	self._file_.close()
+
+    #
+    # Initialization routines
+    #
+    def open(self, name, mode):
+	import __builtin__
+
+	self._name_ = name
+	self._mode_ = mode
+	self._file_ = __builtin__.open(name, mode)
+	# Copy basic file methods
+	for method in self._file_.__methods__:
+	    setattr(self, method, getattr(self._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._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._mode_)
+
+    def flags(self, which):
+	import fcntl, FCNTL
+
+	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
+
+	if '=' not in which:
+	    cur_fl = fcntl.fcntl(self._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(self._file_.fileno(), FCNTL.F_SETFL, l_flags)
+
+	if 'c' in which:
+	    arg = ('!' not in which)	# 1 is close
+	    l_flags = fcntl.fcntl(self._file_.fileno(), FCNTL.F_SETFD, arg)
+
+	if '?' in which:
+	    which = ''
+	    l_flags = fcntl.fcntl(self._file_.fileno(), FCNTL.F_GETFL, 0)
+	    if FCNTL.O_APPEND & l_flags: which = which + 'a'
+	    if fcntl.fcntl(self._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_WRLCK
+	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'
+
+	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:
+	    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):
+    return _posixfile_().open(name, mode)
+
+#
+# End of posixfile.py
+#