Raise an exception if an attempt is made to insert more session data into the ActiveRecordStore data column than the column can hold. Closes #2234.

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@2612 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

4 files changed, 56 insertions, 4 deletions

diff --git a/actionpack/CHANGELOG b/actionpack/CHANGELOG
index 75c72ba617..4a703ac88a 100644
--- a/actionpack/CHANGELOG
+++ b/actionpack/CHANGELOG
@@ -1,5 +1,7 @@
 *SVN*
 
+* Raise an exception if an attempt is made to insert more session data into the ActiveRecordStore data column than the column can hold. #2234.  [justin@textdrive.com]
+
 * Removed references to assertions.rb from actionpack assert's backtraces. Makes error reports in functional unit tests much less noisy. [Tobias Luetke]
 
 * Updated and clarified documentation for JavaScriptHelper to be more concise about the various options for including the JavaScript libs. [Thomas Fuchs]
diff --git a/actionpack/lib/action_controller/base.rb b/actionpack/lib/action_controller/base.rb
index a019a4e1fc..6b9456cf1f 100755
--- a/actionpack/lib/action_controller/base.rb
+++ b/actionpack/lib/action_controller/base.rb
@@ -25,6 +25,9 @@ module ActionController #:nodoc:
   end
   class MissingFile < ActionControllerError #:nodoc:
   end
+  class SessionOverflowError < ActionControllerError #:nodoc:
+    DEFAULT_MESSAGE = 'Your session data is larger than the data column in which it is to be stored. You must increase the size of your data column if you intend to store large data.'
+  end
   class DoubleRenderError < ActionControllerError #:nodoc:
     DEFAULT_MESSAGE = "Render and/or redirect were called multiple times in this action. Please note that you may only call render OR redirect, and only once per action. Also note that neither redirect nor render terminate execution of the action, so if you want to exit an action after redirecting, you need to do something like \"redirect_to(...) and return\". Finally, note that to cause a before filter to halt execution of the rest of the filter chain, the filter must return false, explicitly, so \"render(...) and return false\"." 
 
diff --git a/actionpack/lib/action_controller/session/active_record_store.rb b/actionpack/lib/action_controller/session/active_record_store.rb
index 130ce12150..90d9f3fbe1 100644
--- a/actionpack/lib/action_controller/session/active_record_store.rb
+++ b/actionpack/lib/action_controller/session/active_record_store.rb
@@ -33,13 +33,23 @@ class CGI
     #
     # The fast SqlBypass class is a generic SQL session store.  You may
     # use it as a basis for high-performance database-specific stores.
+    #
+    # If the data you are attempting to write to the +data+ column is larger
+    # than the column's size limit, ActionController::SessionOverflowError 
+    # will be raised.
     class ActiveRecordStore
       # The default Active Record class.
       class Session < ActiveRecord::Base
         before_save   :marshal_data!
+        before_save   :ensure_data_not_too_big
         before_update :data_changed?
 
         class << self
+
+          def data_column_size_limit
+            connection.columns(table_name).find {|column| column.name == 'data'}.limit
+          end
+
           # Hook to set up sessid compatibility.
           def find_by_session_id(session_id)
             setup_sessid_compatibility!
@@ -55,7 +65,7 @@ class CGI
               CREATE TABLE #{table_name} (
                 id INTEGER PRIMARY KEY,
                 #{connection.quote_column_name('session_id')} TEXT UNIQUE,
-                #{connection.quote_column_name('data')} TEXT
+                #{connection.quote_column_name('data')} TEXT(255)
               )
             end_sql
           end
@@ -109,6 +119,15 @@ class CGI
             old_fingerprint, @fingerprint = @fingerprint, self.class.fingerprint(read_attribute('data'))
             old_fingerprint != @fingerprint
           end
+
+          # Ensures that the data about to be stored in the database is not
+          # larger than the data storage column. Raises
+          # ActionController::SessionOverflowError.
+          def ensure_data_not_too_big
+            return unless limit = self.class.data_column_size_limit
+            raise ActionController::SessionOverflowError, ActionController::SessionOverflowError::DEFAULT_MESSAGE if read_attribute('data').size > limit
+          end
+
       end
 
       # A barebones session store which duck-types with the default session
@@ -126,9 +145,6 @@ class CGI
       class SqlBypass
         # Use the ActiveRecord::Base.connection by default.
         cattr_accessor :connection
-        def self.connection
-          @@connection ||= ActiveRecord::Base.connection
-        end
 
         # The table name defaults to 'sessions'.
         cattr_accessor :table_name
@@ -143,6 +159,11 @@ class CGI
         @@data_column = 'data'
 
         class << self
+
+          def connection
+            @@connection ||= ActiveRecord::Base.connection
+          end
+
           # Look up a session by id and unmarshal its data if found.
           def find_by_session_id(session_id)
             if record = @@connection.select_one("SELECT * FROM #{@@table_name} WHERE #{@@session_id_column}=#{@@connection.quote(session_id)}")
@@ -201,6 +222,7 @@ class CGI
 
         def save
           marshaled_data = self.class.marshal(data)
+
           if @new_record
             @new_record = false
             @@connection.update <<-end_sql, 'Create session'
@@ -231,6 +253,7 @@ class CGI
             end_sql
           end
         end
+
       end
 
       # The class used for session storage.  Defaults to
@@ -278,6 +301,7 @@ class CGI
           @session = nil
         end
       end
+
     end
   end
 end
diff --git a/actionpack/test/controller/active_record_store_test.rb b/actionpack/test/controller/active_record_store_test.rb
index 99034880dc..be7f911e70 100644
--- a/actionpack/test/controller/active_record_store_test.rb
+++ b/actionpack/test/controller/active_record_store_test.rb
@@ -53,6 +53,7 @@ module CommonActiveRecordStoreTests
       @new_session.close
     end
   end
+
 end
 
 class ActiveRecordStoreTest < Test::Unit::TestCase
@@ -77,6 +78,28 @@ class ActiveRecordStoreTest < Test::Unit::TestCase
   end
 end
 
+class ColumnLimitTest < Test::Unit::TestCase
+
+  def setup
+    @session_class = CGI::Session::ActiveRecordStore::Session
+    @session_class.create_table!
+  end
+
+  def teardown
+    @session_class.drop_table!
+  end
+
+  def test_protection_from_data_larger_than_column
+    # Can't test this unless there is a limit
+    return unless limit = @session_class.data_column_size_limit
+    too_big = ':(' * limit
+    s = @session_class.new(:session_id => '666', :data => {'foo' => too_big})
+    s.data
+    assert_raises(ActionController::SessionOverflowError) { s.save }
+  end
+
+end
+
 
 class DeprecatedActiveRecordStoreTest < ActiveRecordStoreTest
   def setup