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<h2>Examples</h2>

Some typical example uses:
<ol>
<li><a href="#with">Restoring a stack trace with line numbers</a></li>
<li><a href="#withverbose">Restoring a stack trace with line numbers
    (verbose)</a></li>
<li><a href="#without">Restoring a stack trace without line numbers</a></li>
</ol>

<h3><a name="with">Restoring a stack trace with line numbers</a></h3>

Assume for instance ProGuard itself has been obfuscated using the following
extra options:
<pre>
-printmapping mapping.txt

-renamesourcefileattribute MyApplication
-keepattributes SourceFile,LineNumberTable
</pre>
<p>

Now assume the processed application throws an exception:
<pre>
java.io.IOException: Can't read [dummy.jar] (No such file or directory)
	at proguard.y.a(MyApplication:188)
	at proguard.y.a(MyApplication:158)
	at proguard.y.a(MyApplication:136)
	at proguard.y.a(MyApplication:66)
	at proguard.ProGuard.c(MyApplication:218)
	at proguard.ProGuard.a(MyApplication:82)
	at proguard.ProGuard.main(MyApplication:538)
Caused by: java.io.IOException: No such file or directory
	at proguard.d.q.a(MyApplication:50)
	at proguard.y.a(MyApplication:184)
	... 6 more
</pre>
<p>

If we have saved the stack trace in a file <code>stacktrace.txt</code>, we can
use the following command to recover the stack trace:
<pre>
<b>java -jar retrace.jar mapping.txt stacktrace.txt</b>
</pre>
<p>

The output will correspond to the original stack trace:
<pre>
java.io.IOException: Can't read [dummy.jar] (No such file or directory)
	at proguard.InputReader.readInput(InputReader.java:188)
	at proguard.InputReader.readInput(InputReader.java:158)
	at proguard.InputReader.readInput(InputReader.java:136)
	at proguard.InputReader.execute(InputReader.java:66)
	at proguard.ProGuard.readInput(ProGuard.java:218)
	at proguard.ProGuard.execute(ProGuard.java:82)
	at proguard.ProGuard.main(ProGuard.java:538)
Caused by: java.io.IOException: No such file or directory
	at proguard.io.DirectoryPump.pumpDataEntries(DirectoryPump.java:50)
	at proguard.InputReader.readInput(InputReader.java:184)
	... 6 more
</pre>

<h3><a name="withverbose">Restoring a stack trace with line numbers (verbose)</a></h3>

In the previous example, we could also use the verbose flag:
<pre>
<b>java -jar retrace.jar -verbose mapping.txt stacktrace.txt</b>
</pre>
<p>

The output will then look as follows:
<pre>
java.io.IOException: Can't read [dummy.jar] (No such file or directory)
	at proguard.InputReader.void readInput(java.lang.String,proguard.ClassPathEntry,proguard.io.DataEntryReader)(InputReader.java:188)
	at proguard.InputReader.void readInput(java.lang.String,proguard.ClassPath,int,int,proguard.io.DataEntryReader)(InputReader.java:158)
	at proguard.InputReader.void readInput(java.lang.String,proguard.ClassPath,proguard.io.DataEntryReader)(InputReader.java:136)
	at proguard.InputReader.void execute(proguard.classfile.ClassPool,proguard.classfile.ClassPool)(InputReader.java:66)
	at proguard.ProGuard.void readInput()(ProGuard.java:218)
	at proguard.ProGuard.void execute()(ProGuard.java:82)
	at proguard.ProGuard.void main(java.lang.String[])(ProGuard.java:538)
Caused by: java.io.IOException: No such file or directory
	at proguard.io.DirectoryPump.void pumpDataEntries(proguard.io.DataEntryReader)(DirectoryPump.java:50)
	at proguard.InputReader.void readInput(java.lang.String,proguard.ClassPathEntry,proguard.io.DataEntryReader)(InputReader.java:184)
	... 6 more
</pre>


<h3><a name="without">Restoring a stack trace without line numbers</a></h3>

Assume for instance ProGuard itself has been obfuscated using the following
extra options, this time without preserving the line number tables:
<pre>
-printmapping mapping.txt
</pre>
<p>

A stack trace <code>stacktrace.txt</code> will then lack line number
information, showing "Unknown source" instead:
<pre>
java.io.IOException: Can't read [dummy.jar] (No such file or directory)
	at proguard.y.a(Unknown Source)
	at proguard.y.a(Unknown Source)
	at proguard.y.a(Unknown Source)
	at proguard.y.a(Unknown Source)
	at proguard.ProGuard.c(Unknown Source)
	at proguard.ProGuard.a(Unknown Source)
	at proguard.ProGuard.main(Unknown Source)
Caused by: java.io.IOException: No such file or directory
	at proguard.d.q.a(Unknown Source)
	... 7 more
</pre>
<p>

We can still use the same command to recover the stack trace:
<pre>
<b>java -jar retrace.jar mapping.txt stacktrace.txt</b>
</pre>
<p>

The output will now list all alternative original method names for each
ambiguous obfuscated method name:
<pre>
java.io.IOException: Can't read [dummy.jar] (No such file or directory)
	at proguard.InputReader.execute(InputReader.java)
	                        readInput(InputReader.java)
	at proguard.InputReader.execute(InputReader.java)
	                        readInput(InputReader.java)
	at proguard.InputReader.execute(InputReader.java)
	                        readInput(InputReader.java)
	at proguard.InputReader.execute(InputReader.java)
	                        readInput(InputReader.java)
	at proguard.ProGuard.readInput(ProGuard.java)
	at proguard.ProGuard.execute(ProGuard.java)
	                     optimize(ProGuard.java)
	                     createPrintStream(ProGuard.java)
	                     closePrintStream(ProGuard.java)
	                     fileName(ProGuard.java)
	at proguard.ProGuard.main(ProGuard.java)
Caused by: java.io.IOException: No such file or directory
	at proguard.io.DirectoryPump.pumpDataEntries(DirectoryPump.java)
	                             readFiles(DirectoryPump.java)
</pre>
<p>

For instance, ReTrace can't tell if the method <code>a</code> corresponds
to <code>execute</code> or to <code>readInput</code>, so it lists both. You
need to figure it out based on your knowledge of the application. Having line
numbers and unambiguous names clearly is a lot easier, so you should consider
<a href="../examples.html#stacktrace">preserving the line numbers</a> when you
obfuscate your application.

<hr />
<address>
Copyright &copy; 2002-2017
<a target="other" href="http://www.lafortune.eu/">Eric Lafortune</a> @ <a target="top" href="http://www.guardsquare.com/">GuardSquare</a>.
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