[FELIX-2338] Problem in the Configuration Render

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: webconsole-3.0.0
• Fix Version/s: webconsole-3.1.0
• Component/s: Web Console
• Environment: Skelmir CEE-J 4 VM
• Assignee: Valentin Valchev
• Reporter: Valentin Valchev
• Created: 13/May/10 06:12
• Updated: 19/Dec/16 17:23
• Resolved: 04/Jun/10 07:23

Description

With some JVM implementation like Skelmir CEE-J, the configurations will not be printed correctly and the server will generate internal server error.

In the log there is a long stack trace:
— cut here –
Wed, 12 May 2010 13:42:40 GMT 8 ERROR [HTTP] Problem while making answer to request /system/console/config/Configurations.nfo from client address null
java.lang.StackOverflowError
at java/io/PrintWriter.write (Unknown Source, bco=33)
at java/io/PrintStream.write (Unknown Source, bco=88)
at java/io/PrintStream.writeInternal (Unknown Source, bco=20)
at java/io/PrintStream.print (Unknown Source, bco=5)
at java/io/PrintStream.println (Unknown Source, bco=9)
at org/apache/felix/webconsole/internal/misc/ConfigurationRender$HtmlConfigurationWriter.write (ConfigurationRender.java:508)
at java/io/PrintWriter.write (Unknown Source, bco=25)
at org/apache/felix/webconsole/internal/misc/ConfigurationRender$HtmlConfigurationWriter.writeFiltered (ConfigurationRender.java:540)
at org/apache/felix/webconsole/internal/misc/ConfigurationRender$HtmlConfigurationWriter.write (ConfigurationRender.java:510)
at java/io/PrintWriter.write (Unknown Source, bco=25)
at org/apache/felix/webconsole/internal/misc/ConfigurationRender$HtmlConfigurationWriter.writeFiltered (ConfigurationRender.java:540)
at org/apache/felix/webconsole/internal/misc/ConfigurationRender$HtmlConfigurationWriter.write (ConfigurationRender.java:510)
at java/io/PrintWriter.write (Unknown Source, bco=25)
at org/apache/felix/webconsole/internal/misc/ConfigurationRender$HtmlConfigurationWriter.writeFiltered (ConfigurationRender.java:540)
at org/apache/felix/webconsole/internal/misc/ConfigurationRender$HtmlConfigurationWriter.write (ConfigurationRender.java:510)
at java/io/PrintWriter.write (Unknown Source, bco=25)
— cut here –

These are the first few lines only. Obviously the different implementation of PrintWriter makes an endless loop between methods.

I'm attaching a patch that:
1. fixes the above problem
2. optimizes the writer by escaping the symbols on the fly one by one (writing char by char is not a problem, because the Servet output is already buffered)
3. because of 2 it doesn't escape the string /using WebConsoleUtil.escapeHtml()/ and then write escaped one; and doesn't create a new StringBuffer + String objects. This reduces the used temporary memory and should have also influence on performance.