Support to S3's GET link with response-* params

lib/awsbase/right_awsbase.rb

@@ -121,6 +121,16 @@ def self.URLencode(raw)
       e.gsub(/\+/, "%2b")
     end
 
+    def self.CGIescape(raw)
+      e = CGI::escape raw
+      e.gsub(/\+/, "%20")
+    end
+
+    def self.CGIunescape(escaped)
+      r = escaped.gsub("%20", "+")
+      CGI::unescape r
+    end
+
     def self.allow_only(allowed_keys, params)
       bogus_args = []
       params.keys.each {|p| bogus_args.push(p) unless allowed_keys.include?(p) }

lib/awsbase/support.rb

@@ -31,5 +31,83 @@ class String #:nodoc:
     def right_underscore
       self.gsub(/[A-Z]/){|match| "#{$`=='' ? '' : '_'}#{match.downcase}" }
     end
-
+
+    # Constantize tries to find a declared constant with the name specified
+    # in the string. It raises a NameError when the name is not in CamelCase
+    # or is not initialized.
+    #
+    # Examples
+    #   "Module".constantize #=> Module
+    #   "Class".constantize #=> Class
+    def right_constantize()
+      unless /\A(?:::)?([A-Z]\w*(?:::[A-Z]\w*)*)\z/ =~ self
+        raise NameError, "#{self.inspect} is not a valid constant name!"
+      end
+      Object.module_eval("::#{$1}", __FILE__, __LINE__)
+    end
+
+    def right_camelize()
+      self.dup.split(/_/).map{ |word| word.capitalize }.join('')
+    end
+
+  end
+
+
+  class Object #:nodoc:
+    # "", "   ", nil, [], and {} are blank
+    def right_blank?
+      if respond_to?(:empty?) && respond_to?(:strip)
+        empty? or strip.empty?
+      elsif respond_to?(:empty?)
+        empty?
+      else
+        !self
+      end
+    end
+  end
+
+  class NilClass #:nodoc:
+    def right_blank?
+      true
+    end
+  end
+
+  class FalseClass #:nodoc:
+    def right_blank?
+      true
+    end
+  end
+
+  class TrueClass #:nodoc:
+    def right_blank?
+      false
+    end
+  end
+
+  class Array #:nodoc:
+    alias_method :right_blank?, :empty?
+  end
+
+  class Hash #:nodoc:
+    alias_method :right_blank?, :empty?
+
+    # Return a new hash with all keys converted to symbols.
+    def right_symbolize_keys
+      inject({}) do |options, (key, value)|
+        options[key.to_sym] = value
+        options
+      end
+    end
+  end
+
+  class String #:nodoc:
+    def right_blank?
+      empty? || strip.empty?
+    end
+  end
+
+  class Numeric #:nodoc:
+    def right_blank?
+      false
+    end
   end

lib/s3/right_s3_interface.rb

@@ -114,6 +114,16 @@ def canonical_string(method, path, headers={}, expires=nil) # :nodoc:
       out_string << '?torrent'  if path[/[&?]torrent($|&|=)/]
       out_string << '?location' if path[/[&?]location($|&|=)/]
       out_string << '?logging'  if path[/[&?]logging($|&|=)/]  # this one is beta, no support for now
+      if method == 'GET'
+        # fetch all response-* param pairs recursively (dirty method)
+        while path[/[&?](response\-[A-Za-z\-]+=[^&]+)($|&)/]
+          resp = $1
+          # string-to-sign must be un-encoded, so an unescape process is taken on resp,
+          # which is already escaped in get_link()
+          out_string << ("#{out_string[/\?/] ? "&" : "?"}#{AwsUtils.CGIunescape(resp)}")
+          path = path.gsub(/[&?]#{resp}/, '')
+        end
+      end
       out_string
     end
 
@@ -916,8 +926,30 @@ def put_link(bucket, key, data=nil, expires=nil, headers={})
       #  s3.get_link('my_awesome_bucket',key) #=> https://s3.amazonaws.com:443/my_awesome_bucket/asia%2Fcustomers?Signature=QAO...
       #
       # see http://docs.amazonwebservices.com/AmazonS3/2006-03-01/VirtualHosting.html
-    def get_link(bucket, key, expires=nil, headers={})
-      generate_link('GET', headers.merge(:url=>"#{bucket}/#{CGI::escape key}"), expires)
+      #
+      # To specify +response+-* parameters, gather them together in a hash at the 5th parameter,
+      # with +expires+ set to +nil+ and +headers+ to {} (or whatever values you want):
+      # 
+      #  s3.get_link('my_awesome_bucket', key, nil, {}, {
+      #              "response-content-disposition" => "attachment; filename=café.png", # supports non-ascii chars
+      #              "response-content-type" => "image/png"})
+      #  #=> https://s3.amazonaws.com:443/my_awesome_bucket/asia%2Fcustomers?response-content-disposition=attachment%3B%20filename%3Dcaf%25C3%25A9.png
+      #      &response-content-type=image%2Fpng&Signature=wio...
+    def get_link(bucket, key, expires=nil, headers={}, response_params={})
+      if response_params == {} || response_params == nil
+        generate_link('GET', headers.merge(:url=>"#{bucket}/#{CGI::escape key}"), expires)
+      else
+        params_s = response_params.sort { |a,b| a[0] <=> b[0] }.map { |x| 
+          if (x[0] == 'response-content-disposition')
+            if (x[1][/(.+filename=)(.+)/])
+              # escape the filename with "+" being replaced with "%20" to avoid enconding issue on non-ascii chars
+              x[1] = "#{$1}#{AwsUtils.CGIescape($2)}"
+            end
+          end
+          "#{x[0]}=#{AwsUtils.CGIescape(x[1])}" # collect escaped parameters
+        }.join('&')
+        generate_link('GET', headers.merge(:url=>"#{bucket}/#{CGI::escape key}?#{params_s}"), expires)
+      end
     rescue
       on_exception
     end