How is the code stored in an executable? [closed]

Question

I read that an executable stores the code in different sections. For example, a separate section for data etc. Is this generic across different platforms such as Win or MacOs or Linux?

Some insight into it would be really helpful.

Answer 1

You are correct in that an executable has several sections or segments: Not all of them, however, are code.

There is usually one segment for code - in ELF and PE, this is usually called .text. Additional ones exist to store dynamic linkage data, hard coded strings, read only data, global variables, etc.

To see these for yourself, rather than Wiki and Google , try hands on:

In Windows: You have a tool called DUMPBIN.EXE , part of visual studio. If you can't get your hands on that, use Dependency Walker (which is freely downloadable). This will parse PE and PE32+ (that is, 64-bit) files

In Linux: Use objdump -x , or readelf (both are pretty much the same, though with slightly different options) for ELF files.

In Mac: Use otool -l to see the load commands (which show you the sections and the segments) in Mach-O files.

Using either or all tools will hopefully get you a better idea of how things work.

Hope this helps,

TG