From 16da2ea2a6c6d9b70ea3b3424d80b0f8a68b6cec Mon Sep 17 00:00:00 2001
From: Steven McDonald <steven@vader.steven-mcdonald.id.au>
Date: Sat, 13 Oct 2012 13:57:01 +1100
Subject: [PATCH] Initial working prototype

---
 bin/aids    |  48 ++++++++++++++++++++++
 lib/aids.rb | 115 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 163 insertions(+)
 create mode 100755 bin/aids
 create mode 100644 lib/aids.rb

diff --git a/bin/aids b/bin/aids
new file mode 100755
index 0000000..7b3fa50
--- /dev/null
+++ b/bin/aids
@@ -0,0 +1,48 @@
+#!/usr/bin/ruby1.8
+
+require 'lib/aids'
+
+def main(argv)
+	svc = AIDS::Service.new(argv[1]) if argv[1]
+	case argv[0]
+		when 'enable'
+			usage unless svc
+			svc.enable!
+		when 'disable'
+			usage unless svc
+			svc.disable!
+		when 'list'
+			if svc
+				puts svc.status
+			else
+				AIDS.get_all_services.sort_by{|s|s.name}.each do |s|
+					puts "#{s.name}: #{s.status}"
+				end
+			end
+		else
+			usage
+	end
+end
+
+def usage
+	$stderr.puts <<-EOF
+AIDS - Assistant for Initialisation of Debian Services
+
+Usage: #{$0} command [service]
+
+Command may be one of:
+
+  - enable
+      Enables the service.
+
+  - disable
+      Disables the service.
+
+  - list
+      Lists the current status of the service, or of all services if
+      none is provided.
+	EOF
+	exit 1
+end
+
+main(ARGV) if $0 == __FILE__
diff --git a/lib/aids.rb b/lib/aids.rb
new file mode 100644
index 0000000..c2a7e66
--- /dev/null
+++ b/lib/aids.rb
@@ -0,0 +1,115 @@
+module AIDS
+	RUNLEVEL_SINGLE          = 'S'
+	RUNLEVEL_MULTI_TO_SINGLE = '1'
+	RUNLEVEL_MULTI           = '2'
+	RUNLEVEL_HALT            = '0'
+	RUNLEVEL_REBOOT          = '6'
+
+	class Service
+		attr_reader :name
+
+		def initialize(name)
+			if name.nil? or name.empty? or not name.is_a?(String)
+				raise Exception.new("Service name must be a non-empty string, got #{name.inspect}.")
+			end
+			name = $1 if name =~ %r{^/etc/init\.d/(.+)$}
+			if name =~ /[^[:alnum:]\-.]/
+				raise Exception.new("Invalid init script name: #{name}.")
+			end
+			unless File.exist?("/etc/init.d/#{name}")
+				raise Exception.new("Unknown service: #{name}.")
+			end
+			@name = name
+		end
+
+		def enable!
+			start_on_runlevel!(RUNLEVEL_MULTI)
+		end
+
+		def disable!
+			stop_on_runlevel!(RUNLEVEL_MULTI)
+		end
+
+		def enabled?
+			started_on_runlevel?(RUNLEVEL_MULTI)
+		end
+
+		def status
+			if started_on_runlevel?(RUNLEVEL_MULTI)
+				:enabled
+			elsif stopped_on_runlevel?(RUNLEVEL_MULTI)
+				:disabled
+			else
+				:unknown
+			end
+		end
+
+		private
+
+		def started_on_runlevel?(runlevel)
+			AIDS.validate_runlevel(runlevel)
+			not Dir.glob("/etc/rc#{runlevel}.d/S[0-9][0-9]#{@name}").empty?
+		end
+
+		def stopped_on_runlevel?(runlevel)
+			AIDS.validate_runlevel(runlevel)
+			not Dir.glob("/etc/rc#{runlevel}.d/K[0-9][0-9]#{@name}").empty?
+		end
+
+		def start_on_runlevel!(runlevel)
+			AIDS.validate_runlevel(runlevel)
+			return true if started_on_runlevel?(runlevel)
+			updatercd(:enable, runlevel)
+		end
+
+		def stop_on_runlevel!(runlevel)
+			AIDS.validate_runlevel(runlevel)
+			return true if stopped_on_runlevel?(runlevel)
+			updatercd(:disable, runlevel)
+		end
+
+		def set_default_runlevels!
+			updatercd(:remove)
+			updatercd(:defaults)
+		end
+
+		def updatercd(action, runlevel=nil)
+			unless [:enable, :disable, :remove, :defaults].include?(action)
+				raise Exception.new("Invalid action for updatercd: #{action}.")
+			end
+			AIDS.validate_runlevel(runlevel) if runlevel
+			# update-rc.d will baulk at being told to do anything with
+			# these runlevels.
+			if ['0', '1', '6'].include?(runlevel.to_s)
+				raise Exception.new("Unable to comply: update-rc.d is balls.")
+			end
+			pid = Process.fork do
+				$stdout.close
+				$stderr.close
+				Kernel.exec(
+					'/usr/sbin/update-rc.d',
+					@name,
+					action.to_s,
+					runlevel.to_s
+				)
+			end
+			Process.wait(pid)
+			if (rc = $?.exitstatus) != 0
+				raise Exception.new("update-rc.d returned #{rc}")
+			end
+		end
+	end
+
+	def self.get_all_services
+		Dir.glob("/etc/init.d/*").map do |f|
+			next unless File.executable?(f)
+			Service.new(f)
+		end.compact
+	end
+
+	def self.validate_runlevel(runlevel)
+		unless ['0', '1', '2', '3', '4', '5', '6', 'S'].include?(runlevel.to_s)
+			raise Exception.new("Invalid runlevel: #{runlevel}.")
+		end
+	end
+end
-- 
2.30.2