For many higher-level programming languages, compilation is a vital part of the process of converting an application from source code to machine-readable binary code. During this process, a compiler may make minor changes to the code to make it as fast and efficient as possible.
The process of compiling and optimizing an application can make it more difficult to reverse engineer. This chapter describes how to find a starting point for reversing an application and some of the common actions that compilers take that can complicate reverse engineering.
Finding Starting Code
When code is compiled, the compiler introduces a large amount of boilerplate that is executed before the actual application code is ever called. When reverse engineering, one of the art forms you'll need to master is how to skip over this and focus on the target code, not the boilerplate setup. However, identifying the entry point into the target code can be complex.
When reversing someone else's code, it's unlikely that the code will be compiled with debugging symbols. This means function and variable names and other information that could provide a hint regarding the actual code's entry point have been stripped from the application. Figure 8.1 shows what opening a file without debugging symbols looks like in gdb.
Figure 8.1: Application without debugging symbols in
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