redmine/lib/redmine/thumbnail.rb

# frozen_string_literal: true

# Redmine - project management software
# Copyright (C) 2006-2019  Jean-Philippe Lang
#
# This program 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., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.

require 'fileutils'
require 'mimemagic'

module Redmine
  module Thumbnail
    extend Redmine::Utils::Shell

    CONVERT_BIN = (Redmine::Configuration['imagemagick_convert_command'] || 'convert').freeze
    ALLOWED_TYPES = %w(image/bmp image/gif image/jpeg image/png application/pdf)

    # Generates a thumbnail for the source image to target
    def self.generate(source, target, size, is_pdf = false)
      return nil unless convert_available?
      return nil if is_pdf && !gs_available?
      unless File.exists?(target)
        mime_type = File.open(source) {|f| MimeMagic.by_magic(f).try(:type) }
        return nil if mime_type.nil?
        return nil if !ALLOWED_TYPES.include? mime_type
        return nil if is_pdf && mime_type != "application/pdf"

        # Make sure we only invoke Imagemagick if the file type is allowed
        unless File.open(source) {|f| ALLOWED_TYPES.include? MimeMagic.by_magic(f).try(:type) }
          return nil
        end
        directory = File.dirname(target)
        unless File.exists?(directory)
          FileUtils.mkdir_p directory
        end
        size_option = "#{size}x#{size}>"

        if is_pdf
          cmd = "#{shell_quote CONVERT_BIN} #{shell_quote "#{source}[0]"} -thumbnail #{shell_quote size_option} #{shell_quote "png:#{target}"}"
        else
          cmd = "#{shell_quote CONVERT_BIN} #{shell_quote source} -auto-orient -thumbnail #{shell_quote size_option} #{shell_quote target}"
        end
        unless system(cmd)
          logger.error("Creating thumbnail failed (#{$?}):\nCommand: #{cmd}")
          return nil
        end
      end
      target
    end

    def self.convert_available?
      return @convert_available if defined?(@convert_available)
      begin
        `#{shell_quote CONVERT_BIN} -version`
        @convert_available = $?.success?
      rescue
        @convert_available = false
      end
      logger.warn("Imagemagick's convert binary (#{CONVERT_BIN}) not available") unless @convert_available
      @convert_available
    end

    def self.gs_available?
      return @gs_available if defined?(@gs_available)

      if Redmine::Platform.mswin?
        @gs_available = false
      else
        begin
          `gs -version`
          @gs_available = $?.success?
        rescue
          @gs_available = false
        end
      end
      @gs_available
    end

    def self.logger
      Rails.logger
    end
  end
end