## Usage

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. Blank lines and unrecognized lines are ignored, as far as possible.

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:

  `%c` | matches a class name (e.g. "`myapplication.MyClass`").
  `%C` | matches a class name with slashes (e.g. "`myapplication/MyClass`").
  `%t` | matches a field type or method return type (e.g. "`myapplication.MyClass[]`").
  `%f` | matches a field name (e.g. "`myField`").
  `%m` | matches a method name (e.g. "`myMethod`").
  `%a` | matches a list of method arguments (e.g. "`boolean,int`").
  `%s` | matches a source file name (e.g. "`MyClass.java`").
  `%l` | matches a line number inside a method (e.g. "`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" myapplication.MyException: Some message
              at myapplication.MyClass.myMethod(SourceFile: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.