You can find the ReTrace jar in the lib directory of the ProGuard distribution. To run ReTrace, just type:

java -jar retrace.jar [options...] mapping_file [stacktrace_file]

Alternatively, the bin directory contains some short Linux and Windows scripts containing this command. These are the arguments:

mapping_file : Specifies the name of the mapping file, produced by ProGuard with the option “-printmapping mapping_file”, while obfuscating the application that produced the stack trace.

stacktrace_file : Optionally specifies the name of the file containing the stack trace. If no file is specified, a stack trace is read from the standard input. The stack trace must be encoded with UTF-8 encoding. Blank lines and unrecognized lines are ignored.

The following options are supported:

-verbose : Specifies to print out more informative stack traces that include not only method names, but also method return types and arguments.

-regex regular_expression

: Specifies the regular expression that is used to parse the lines in the stack trace. Specifying a different regular expression allows to de-obfuscate more general types of input than just stack traces. The default is suitable for stack traces produced by most JVMs:

    (?:.*?\bat\s+%c\.%m\s*\(%s(?::%l)?\)\s*(?:~\[.*\])?)|(?:(?:.*?[:"]\s+)?%c(?::.*)?)

The regular expression is a Java regular expression (cfr. the documentation of java.util.regex.Pattern), with a few additional wildcards:

Wildcard	Description	Example
%c	matches a class name	com.example.MyClass
%C	matches a class name with slashes	com/example/MyClass
%t	matches a field type or method return type	com.example.MyClass[]
%f	matches a field name	myField
%m	matches a method name	myMethod
%a	matches a list of method arguments	boolean,int
%s	matches a source file name	MyClass.java
%l	matches a line number inside a method	123

Elements that match these wildcards are de-obfuscated, when possible. Note that regular expressions must not contain any capturing groups. Use non-capturing groups instead: (?:...)

The default expression for instance matches the following lines:

Exception in thread "main" com.example.MyException: Some message
    at com.example.MyClass.myMethod(MyClass.java:123)

The restored stack trace is printed to the standard output. The completeness of the restored stack trace depends on the presence of line number tables in the obfuscated class files:

• If all line numbers have been preserved while obfuscating the application, ReTrace will be able to restore the stack trace completely.
• If the line numbers have been removed, mapping obfuscated method names back to their original names has become ambiguous. Retrace will list all possible original method names for each line in the stack trace. The user can then try to deduce the actual stack trace manually, based on the logic of the program.

Preserving line number tables is explained in detail in this example in the ProGuard User Manual.

Source file names are currently restored based on the names of the outer-most classes. If you prefer to keep the obfuscated name, you can replace %s in the default regular expression by .*

Unobfuscated elements and obfuscated elements for which no mapping is available will be left unchanged.