# config.rb:
# Very simple config parser. Our config files are sort of cod-PHP.
#
# Copyright (c) 2007 UK Citizens Online Democracy. All rights reserved.
# Email: francis@mysociety.org; WWW: http://www.mysociety.org/
#
# $Id: config.rb,v 1.3 2007/10/24 19:13:07 francis Exp $
module MySociety
module Config
# Parse config files (written in a sort of cod-php, using
# define(OPTION_VALUE_NAME, "value of option");
# to define individual elements.
#
# Example use:
# MySociety::Config.set_file('../conf/general')
# opt = MySociety::Config.get('CONFIG_VARIABLE', DEFAULT_VALUE)
# find_php() -> php_binary
# Try to locate the PHP binary in various sensible places.
def Config.find_php()
path = ENV["PATH"] or '/bin:/usr/bin'
paths = path.split(':')
for dir in path.split(':') +
['/usr/local/bin', '/usr/bin', '/software/bin', '/opt/bin', '/opt/php/bin']
for name in ['php4', 'php', 'php4-cgi', 'php-cgi']
if File.exists?(File.join(dir, name))
return File.join(dir, name)
end
end
end
raise "unable to locate PHP binary, needed to read config file"
end
# Fork a process to the php interpreter
def Config.fork_php
# We need to find the PHP binary.
if @php_path.nil?
@php_path = find_php()
end
# Delete everything from the environment other than our special variable to
# give PHP the config file name. We don't want PHP to pick up other
# information from our environment and turn into an FCGI server or
# something.
# An assignment or a .clone didn't seem to truly copy ENV
store_environ = {}
for k,v in ENV
store_environ[k] = v
end
ENV.clear()
IO.popen(@php_path, "w+") do |child|
yield child
end
ENV.clear()
ENV.update(store_environ)
# check that php exited successfully
if not $?.success?
raise "#{@php_path}: failed status #{$?.to_s}"
end
end
# read_config(FILE) ->
# Read configuration from FILE, which should be the name of a PHP config
# file. This is parsed by PHP, and any defines are extracted as config
# values. "OPTION_" is removed from any names beginning with that.
attr :php_path
def Config.read_config(f)
buf = nil
fork_php do |child|
child.print("<?php $b = get_defined_constants(); require('#{f}');")
child.print('''
$a = array_diff_assoc(get_defined_constants(), $b);
print "start_of_options\n";
foreach ($a as $k => $v) {
print preg_replace("/^OPTION_/", "", $k); /* strip off "OPTION_" if there */
print "\0";
print $v;
print "\0";
}
?>''')
child.close_write()
# skip any header material
line = true
while line
line = child.readline()
if line == "start_of_options\n"
break
else
raise "#{@php_path}: #{f}: failed to read options"
end
end
# read remainder
buf = child.read()
end
# parse out config values
vals = buf.split(/\0/) # option values may be empty
if (vals.size % 2) != 0
raise "#{@php_path}: #{f}: bad option output from subprocess"
end
config = {}
for i in 0..(vals.size / 2 - 1)
config[vals[i*2]] = vals[i*2+1]
end
config["CONFIG_FILE_NAME"] = f
return config
end
# set_file FILENAME [IGNORE_MISSING_FILE]
# Sets the default configuration file, used by mySociety::Config.get.
# IGNORE_MISSING_FILE if set means will not error if the file is missing,
# but instead return default values.
attr :main_config_filename
attr :ignore_missing_file
def Config.set_file(filename, ignore_missing_file = false)
@main_config_filename = filename
@ignore_missing_file = ignore_missing_file
end
# load_default
# Loads and caches default config file, as set with set_file. This
# function is implicitly called by get and get_all.
attr :cached_configs
def Config.load_default()
filename = @main_config_filename
if not filename
raise "Please call MySociety::Config.set_file to specify config file"
end
if not File.exists?(filename)
if @ignore_missing_file
return {"CONFIG_FILE_NAME" => filename + " (missing file)"}
else
raise "File missing '" + filename + "'"
end
end
if @cached_configs.nil?
@cached_configs = {}
end
if not @cached_configs.include?(filename)
@cached_configs[filename] = read_config(filename)
end
return @cached_configs[filename]
end
# get KEY [DEFAULT]
# Returns the constants set for KEY from the configuration file specified
# in set_config_file. The file is automatically loaded and cached. An
# exception is thrown if the value isn't present and no DEFAULT is
# specified.
def Config.get (key, default = nil)
config = load_default()
if config.include?(key)
return config[key]
elsif not default.nil?
return default
else
raise "No value for '#{key}' in '#{config['CONFIG_FILE_NAME']}', and no default specified"
end
end
# getbool KEY [DEFAULT]
# Returns the constants for the give KEY, defaulting to DEFAULT,
# and casts it from 1 / 0 to true or false. This is needed as, unlike
# PHP, Perl and Python for which the config format was initially used,
# Ruby treats 0 as true.
def Config.getbool (key, default = nil)
if default == false
default = 0
elsif default == true
default = 1
end
return get(key, default).to_i > 0
end
end
end
