ioquatix/lsync

# Copyright, 2016, by Samuel G. D. Williams. <http://www.codeotaku.com>
# 
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
# 
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
# 
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
# THE SOFTWARE.

require_relative '../method'
require 'shellwords'

module Synco
    module Methods
        # RSync Exit Codes as of 2011:
        # 0      Success
        # 1      Syntax or usage error
        # 2      Protocol incompatibility
        # 3      Errors selecting input/output files, dirs
        # 4      Requested  action not supported: an attempt was made to manipulate 64-bit files on a platform 
        #        that cannot support them; or an option was specified that is supported by the client and not by the server.
        # 5      Error starting client-server protocol
        # 6      Daemon unable to append to log-file
        # 10     Error in socket I/O
        # 11     Error in file I/O
        # 12     Error in rsync protocol data stream
        # 13     Errors with program diagnostics
        # 14     Error in IPC code
        # 20     Received SIGUSR1 or SIGINT
        # 21     Some error returned by waitpid()
        # 22     Error allocating core memory buffers
        # 23     Partial transfer due to error
        # 24     Partial transfer due to vanished source files
        # 25     The --max-delete limit stopped deletions
        # 30     Timeout in data send/receive
        # 35     Timeout waiting for daemon connection
        
        class RSync < Method
            def default_command
                ['rsync']
            end
            
            def initialize(*command, arguments: [], archive: false, stats: nil, **options)
                if archive
                    arguments << '--archive'
                end
                
                if stats
                    arguments << '--stats'
                end
                
                super
            end
            
            # This escapes the -e argument to rsync, as it's argv parser is a bit.. unique.
            def escape(command)
                case command
                when Array
                    command.collect{|arg| escape(arg)}.join(' ')
                when String
                    command =~ /\s|"|'/ ? command.dump : command
                else
                    escape(command.to_s)
                end
            end
            
            def connect_arguments(master_server, target_server)
                return [] if master_server.same_host?(target_server)
                
                # This gives the command required to connect to the remote server, e.g. `ssh example.com`
                command = target_server.connection_command

                # RSync -e option simply appends the hostname. There is no way to control this behaviour.
                if command.last != target_server.host
                    raise ArgumentError.new("RSync shell requires hostname at end of command! #{command.inspect}")
                else
                    command.pop
                end

                return ['-e', escape(command)]
            end
            
            def call(scope)
                master_server = scope.master_server
                target_server = scope.target_server
                directory = scope.directory
                
                master_server.run(
                    *@command,
                    *@arguments,
                    *directory.arguments,
                    *connect_arguments(master_server, target_server),
                    master_server.connection_string(directory, on: master_server),
                    target_server.connection_string(directory, on: master_server)
                )
            rescue CommandFailure => failure
                raise unless failure.status.to_i == 24
            end
        end
        
        class RSyncSnapshot < RSync
            def initialize(*command, arguments: [], archive: true, stats: true, **options)
                super
            end
            
            def snapshot_name
                @options[:snapshot_name] || SNAPSHOT_NAME
            end
            
            def latest_name
                @options[:latest_name] || LATEST_NAME
            end
            
            def compute_incremental_path(directory)
                File.join(snapshot_name, directory.path)
            end
            
            def compute_link_arguments(directory, incremental_path)
                depth = Directory.depth(incremental_path)
                
                latest_path = File.join("../" * depth, latest_name, directory.path)
                
                return ['--link-dest', latest_path]
            end
            
            def call(scope)
                master_server = scope.master_server
                target_server = scope.target_server
                
                directory = scope.directory
                incremental_path = compute_incremental_path(directory)
                link_arguments = compute_link_arguments(directory, incremental_path)
                
                # Create the destination backup directory
                target_server.run('mkdir', '-p', target_server.full_path(incremental_path))
                
                master_server.run(
                    *@command,
                    *@arguments,
                    *directory.arguments,
                    *connect_arguments(master_server, target_server),
                    *link_arguments,
                    master_server.connection_string(directory, on: master_server),
                    target_server.connection_string(incremental_path, on: master_server)
                )
            rescue CommandFailure => failure
                raise unless failure.status.to_i == 24
            end
        end
    end
end