Mini Shell

# encoding: utf-8
#  Phusion Passenger - https://www.phusionpassenger.com/
#  Copyright (c) 2013-2017 Phusion Holding B.V.
#
#  "Passenger", "Phusion Passenger" and "Union Station" are registered
#  trademarks of Phusion Holding B.V.
#
#  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.

PhusionPassenger.require_passenger_lib 'platform_info'
PhusionPassenger.require_passenger_lib 'utils/shellwords'
require 'fileutils'

module PhusionPassenger
  module Utils

    module Download
      extend self    # Make methods available as class methods.

      def self.included(klass)
        # When included into another class, make sure that Utils
        # methods are made private.
        public_instance_methods(false).each do |method_name|
          klass.send(:private, method_name)
        end
      end

      # Downloads a file from the given URL and saves it to the given filename.
      # Returns whether the download succeeded.
      #
      # Options:
      #
      #   show_progress: whether to show download progress. Default: false.
      #   logger: the logger to use. If not given, this function will log to STDERR.
      #   cacert: a CA certificate file to use for verifying SSL websites.
      #           The default is to use the download tool's down CA database.
      #   use_cache: Whether to copy the file from the download cache, if available.
      #              Default: false.
      #   connect_timeout: The maximum amount of time to spend on DNS lookup
      #                    and establishing the TCP connection. Set to nil to
      #                    disable this timeout. Default: 4.
      #   idle_timeout: The maximum idle read time. Set to nil to set this timeout
      #                 to the default wget value, 900. Set to nil to disable this
      #                 timeout. Default: 5.
      #   total_timeout: The maximum amount of time spent on the whole download
      #                  operation, including connection time. Only has effect on curl.
      #                  Set to nil to disable this timeout. Default: nil.
      def download(url, output, options = {})
        options = {
          :connect_timeout => 4,
          :idle_timeout    => 5
        }.merge(options)
        logger = options[:logger] || Logger.new(STDERR)

        if options[:use_cache] && cache_dir = PhusionPassenger.download_cache_dir
          basename = basename_from_url(url)
          if File.exist?("#{cache_dir}/#{basename}")
            logger.info "Copying #{basename} from #{cache_dir}..."
            FileUtils.cp("#{cache_dir}/#{basename}", output)
            return true
          end
        end

        if PlatformInfo.find_command("curl")
          return download_with_curl(logger, url, output, options)
        elsif PlatformInfo.find_command("wget")
          return download_with_wget(logger, url, output, options)
        else
          logger.error "Could not download #{url}: no download tool found (curl or wget required)"
          return false
        end
      end

    private
      def basename_from_url(url)
        return url.sub(/.*\//, '')
      end

      def download_with_curl(logger, url, output, options)
        command = ["curl", "-f", "-L", "-o", output]
        if options[:show_progress]
          command << "-#"
        else
          command << "-s"
          command << "-S"
        end
        if options[:cacert]
          command << "--cacert"
          command << options[:cacert]
        end
        if options[:connect_timeout]
          command << "--connect-timeout"
          command << options[:connect_timeout].to_s
        end
        if options[:idle_timeout]
          command << "--speed-time"
          command << options[:idle_timeout].to_s
          command << "--speed-limit"
          command << "1"
        end
        if options[:total_timeout]
          command << "--max-time"
          command << options[:total_timeout].to_s
        end
        command << url
        command_str = Shellwords.join(command)
        logger.info("Invoking: #{command_str}")

        if options[:show_progress]
          # If curl errors out we don't want it to display 'curl: ' prefixes,
          # so we parse its output.
          begin
            io = IO.popen("#{command_str} 2>&1", "r")
          rescue SystemCallError => e
            logger.error("Could not invoke curl: #{e}")
            return false
          end
          begin
            non_empty_line_encountered = false
            while !io.eof?
              # We split on "\r" because progress bar lines do not contain "\n".
              data = io.gets("\r")
              data = remove_curl_output_prefix(data)

              # If an error occurs then the first few lines may be empty.
              # Skip those.
              if !non_empty_line_encountered && data =~ /\A\n+/
                data.gsub!(/\A\n+/, '')
              end

              non_empty_line_encountered = true
              STDERR.write(data)
              STDERR.flush
            end
          ensure
            io.close
          end
          result = $?.exitstatus == 0
        else
          begin
            output = `#{command_str} 2>&1`
          rescue SystemCallError => e
            logger.error("Could not invoke curl: #{e}")
            return false
          end
          result = $?.exitstatus == 0
          if !result
            output = remove_curl_output_prefix(output)
            output.chomp!
            logger.error("Could not download #{url}: #{output}")
          end
        end

        return result
      end

      def remove_curl_output_prefix(line)
        return line.gsub(/^curl: (\([0-9]+\) )?/, '')
      end

      def download_with_wget(logger, url, output, options)
        command = ["wget", "--tries=1", "-O", output]
        if !options[:show_progress]
          command << "-nv"
        end
        if options[:cacert]
          command << "--ca-certificate=#{options[:cacert]}"
        end
        if options[:connect_timeout]
          command << "--dns-timeout=#{options[:connect_timeout]}"
          command << "--connect-timeout=#{options[:connect_timeout]}"
        end
        if options[:idle_timeout]
          command << "--timeout=#{options[:idle_timeout]}"
        end
        command << url
        command_str = Shellwords.join(command)
        logger.info("Invoking: #{command_str}")

        if options[:show_progress]
          begin
            result = system(*command)
          rescue SystemCallError => e
            logger.error("Could not invoke wget: #{e}")
            return false
          end
          if !result
            logger.error("Could not download #{url}: #{output}")
          end
        else
          begin
            output = `#{command_str} 2>&1`
          rescue SystemCallError => e
            logger.error("Could not invoke wget: #{e}")
            return false
          end
          result = $?.exitstatus == 0
          if !result
            # Error output may begin with "<URL>:\n" which is redundant.
            output.gsub!(/\A#{Regexp.escape url}:\n/, '')
            output.chomp!
            logger.error("Could not download #{url}: #{output}")
          end
        end

        return result
      end
    end

  end # module Utils
end # module PhusionPassenger