patch: javap does not show SourceDebugExtension properly

[Dmytro Sheyko]

Updated javap output for current and patched 7u25 and 8ea-b91 versions

----------------------------------------
> From: dmytro_sheyko at hotmail.com
> To: jonathan.gibbons at oracle.com; compiler-dev at openjdk.java.net
> Subject: RE: patch: javap does not show SourceDebugExtension properly
> Date: Wed, 26 Jun 2013 10:58:38 +0300
>
> Hello,
>
> I am sending class file sample with sources and javap output:
> Hello.jsp, greeting.jsp - original sources
> Hello_jsp.java, Hello_jsp.class - files generated by Jasper (Apache Tomcat 7.0.41)
> Hello_jsp.*.current.javap, Hello_jsp.*.patched.javap - javap output (without patch and with patch, used jdk1.7.0_25 and jdk1.8.0-ea-b91, however it seems there is no difference in patched classes between repositoried jdk7u/langtools and jdk8/langtools, whatever the case patch (which I sent earlier) is made on jdk8/langtools)
>
> Thanks,
> Dmytro
> ________________________________
>> From: dmytro_sheyko at hotmail.com
>> To: jonathan.gibbons at oracle.com; compiler-dev at openjdk.java.net
>> Subject: RE: patch: javap does not show SourceDebugExtension properly
>> Date: Tue, 25 Jun 2013 23:52:02 +0300
>>
>> Jonathan,
>>
>> This bug does not manifest itself with exception. javap just prints
>>
>> SourceDebugExtension: null
>>
>> In a class file content of SDE attribute appears as UTF-8 string, where
>> the first 4 bytes are 'S', 'M', 'A', 'P'. Existing code of
>> SourceDebugExtension_attribute.getValue() uses readUTF and hence
>> attempts to interpret the first two bytes (i.e. 'S' and 'M') as length
>> of the string and then fails with EOFException. Then it catches this
>> exception and returns null, which, in turn, appears in output.
>>
>> As for sample class file, it's generated by Tomcat 7.0 runtime. I will
>> send it later.
>>
>> Regards,
>> Dmytro
>>
>>> Date: Tue, 25 Jun 2013 12:01:32 -0700
>>> From: jonathan.gibbons at oracle.com
>>> To: compiler-dev at openjdk.java.net
>>> Subject: Re: patch: javap does not show SourceDebugExtension properly
>>>
>>> Dmytro,
>>>
>>> Thank you for your suggestion. Can you provide more details on why the
>>> existing code does not work. Presumably you get an exception -- what is
>>> it? Alternative, can you provide a sample class file for which the
>>> existing code does not work, together with info on which version of
>>> which compiler generated the class file?
>>>
>>> I agree that the change to visitSourceDebugExtension is probably desirable.
>>>
>>> -- Jon
>>>
>>>
>>> On 06/25/2013 11:32 AM, Dmytro Sheyko wrote:
>>>> Hello,
>>>>
>>>> I was trying to get SourceDebugExtension for compiled jsp class
>> using javap (1.7.0_25, 1.8.0-ea-b91) and it printed something like:
>>>>
>>>> SourceFile: "x_jsp.java"
>>>> SourceDebugExtension: null
>>>> minor version: 0
>>>> major version: 50
>>>>
>>>> where expected output is following:
>>>>
>>>> SourceFile: "x_jsp.java"
>>>> SourceDebugExtension:
>>>> SMAP
>>>> x_jsp.java
>>>> JSP
>>>> *S JSP
>>>> *F
>>>> + 0 x.jsp
>>>> x.jsp
>>>> *L
>>>> 1,3:62
>>>> 4:65,4
>>>> 6,4:70
>>>> 9,4:74
>>>> *E
>>>> minor version: 0
>>>> major version: 50
>>>>
>>>> Getting SourceDebugExtension using JDI works well (i.e. class file
>> is correct).
>>>>
>>>> And I would like to propose a patch to fix this issue. Please review.
>>>>
>>>> diff -r b3458329d060
>> src/share/classes/com/sun/tools/classfile/SourceDebugExtension_attribute.java
>>>> ---
>> a/src/share/classes/com/sun/tools/classfile/SourceDebugExtension_attribute.java
>> Mon Jun 24 14:27:32 2013 -0700
>>>> +++
>> b/src/share/classes/com/sun/tools/classfile/SourceDebugExtension_attribute.java
>> Tue Jun 25 20:22:06 2013 +0300
>>>> @@ -25,9 +25,8 @@
>>>>
>>>> package com.sun.tools.classfile;
>>>>
>>>> -import java.io.ByteArrayInputStream;
>>>> -import java.io.DataInputStream;
>>>> import java.io.IOException;
>>>> +import java.nio.charset.Charset;
>>>>
>>>> /**
>>>> * See JVMS, section 4.8.15.
>>>> @@ -38,6 +37,8 @@
>>>> * deletion without notice.</b>
>>>> */
>>>> public class SourceDebugExtension_attribute extends Attribute {
>>>> + private static final Charset UTF8 = Charset.forName("UTF-8");
>>>> +
>>>> SourceDebugExtension_attribute(ClassReader cr, int name_index, int
>> length) throws IOException {
>>>> super(name_index, length);
>>>> debug_extension = new byte[attribute_length];
>>>> @@ -55,12 +56,7 @@
>>>> }
>>>>
>>>> public String getValue() {
>>>> - DataInputStream d = new DataInputStream(new
>> ByteArrayInputStream(debug_extension));
>>>> - try {
>>>> - return d.readUTF();
>>>> - } catch (IOException e) {
>>>> - return null;
>>>> - }
>>>> + return new String(debug_extension, UTF8);
>>>> }
>>>>
>>>> public <R, D> R accept(Visitor<R, D> visitor, D data) {
>>>> diff -r b3458329d060
>> src/share/classes/com/sun/tools/javap/AttributeWriter.java
>>>> --- a/src/share/classes/com/sun/tools/javap/AttributeWriter.java
>> Mon Jun 24 14:27:32 2013 -0700
>>>> +++ b/src/share/classes/com/sun/tools/javap/AttributeWriter.java
>> Tue Jun 25 20:22:06 2013 +0300
>>>> @@ -511,7 +511,10 @@
>>>> }
>>>>
>>>> public Void
>> visitSourceDebugExtension(SourceDebugExtension_attribute attr, Void
>> ignore) {
>>>> - println("SourceDebugExtension: " + attr.getValue());
>>>> + println("SourceDebugExtension:");
>>>> + indent(+1);
>>>> + print(attr.getValue());
>>>> + indent(-1);
>>>> return null;
>>>> }
>>>>
>>>> Regards,
>>>> Dmytro
>>> 		 	   		  
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