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#
# shvfile.py
#
# Implementation of non-destructively reading/writing files containing
# only shell variable declarations and full-line comments.
#
# Copyright 1999 - 2005 Red Hat, Inc.
#
# This is free software; you can redistribute it and/or modify it
# under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
# General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
#
import os
def read(filename):
shv = SHVFile()
shv.open(filename, "r")
shv.parse()
return shv
def rcreate(filename):
shv = SHVFile()
shv.open(filename, "r+")
shv.parse()
return shv
# remove escaped characters in place
def unescape(s):
if not s:
return s
slen = len(s)
if (s[0] == "\"" or s[0] == "'") and s[0] == s[slen-1]:
s = s[1:slen-1]
i = 0
while True:
i = s.find("\\", i)
if i < 0:
break
if i+1 >= len(s):
s = s[0:i]
break
s = s[0:i] + s[i+1:]
i += 1
return s
# create a new string with all necessary characters escaped.
def escape(s):
s = s.replace("\\", "\\\\")
s = s.replace("\"", "\\\"")
s = s.replace("'", "\\\'")
s = s.replace("$", "\\\$")
s = s.replace("~", "\\\~")
s = s.replace("`", "\\\`")
if s.find(" ") > 0 or s.find("\t") > 0:
s = "\"" + s + "\""
return s
class SHVFile:
def __init__(self):
self.filename = ""
self.f = None
self.variables = {}
def open(self, filename, mode):
self.filename = filename
if mode == "r":
self.f = open(filename, mode)
else:
try:
self.f = open(filename, mode)
except IOError:
pass
return
def parse(self):
if not self.f:
return
for line in self.f:
vs = line.rstrip().split("=",1)
if len(vs) < 2:
continue
self.variables[vs[0]] = unescape(vs[1])
def write(self, perms):
if not self.f:
try:
fd = os.open(self.filename, os.O_RDWR | os.O_CREAT, perms)
except OSError:
return
try:
self.f = os.fdopen(fd, "w")
except IOError:
os.close(fd)
return
try:
self.f.seek(0)
self.f.truncate()
for name, value in self.variables.iteritems():
self.f.write(name + "=" + escape(value) + "\n")
self.f.flush()
os.fsync(self.f.fileno())
except IOError:
# we cannot do much in case of error anyway
pass
def close(self):
if self.f:
try:
self.f.close()
except IOError:
# we cannot do much in case of error anyway
pass
self.f = None
def getValue(self, name):
try:
return self.variables[name]
except KeyError:
return ""
def getBoolValue(self, name):
# return True if <key> resolves to any truth value (e.g. "yes", "y", "true")
# return False if <key> resolves to any non-truth value (e.g. "no", "n", "false")
# raise ValueError otherwise
try:
val = self.variables[name].lower()
except KeyError:
raise ValueError
if val == "yes" or val == "true" or val == "t" or val == "y":
return True
if val == "no" or val == "false" or val == "f" or val == "n":
return False
raise ValueError
def setValue(self, name, value):
if not value:
if name in self.variables:
del self.variables[name]
else:
self.variables[name] = value
def setBoolValue(self, name, value):
if value:
self.variables[name] = "yes"
else:
self.variables[name] = "no"