https://github.com/tenderlove/worf

WORF, the DWARF parser
https://github.com/tenderlove/worf

dwarf dwarf-parser ruby

Last synced: 9 months ago
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WORF, the DWARF parser

• Host: GitHub
• URL: https://github.com/tenderlove/worf
• Owner: tenderlove
• License: apache-2.0
• Created: 2021-07-06T23:20:40.000Z (almost 5 years ago)
• Default Branch: main
• Last Pushed: 2022-03-05T19:11:24.000Z (about 4 years ago)
• Last Synced: 2025-05-07T17:29:29.401Z (12 months ago)
• Topics: dwarf, dwarf-parser, ruby
• Language: Ruby
• Homepage:
• Size: 148 KB
• Stars: 10
• Watchers: 3
• Forks: 1
• Open Issues: 1
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

          
# WORF, the DWARF parser

WORF is a DWARF parser that is written in Ruby.  You can use this library to

parse DWARF files.  I usually use this with Mach-O files or ELF files, but

as long as you have an IO object that contains DWARF data, WORF will parse it.

With DWARF data, you can write some debugging utilities, but as an example

I'll write a very simple version of [pahole](https://linux.die.net/man/1/pahole),

a utility that finds holes in structs.

## Example pahole

This example only works on macOS.  We're going to find structs in Ruby that have

holes in them (or wasted space).

First we'll use [OdinFlex](https://github.com/tenderlove/odinflex) to find Ruby's archive file:

```ruby

archive = nil

File.open(RbConfig.ruby) do |f|

  my_macho = OdinFlex::MachO.new f

  my_macho.each do |section|

    if section.symtab?

      archive = section.nlist.find_all(&:archive?).map(&:archive).uniq.first

      break

    end

  end

end

```

Now that we have the archive file, we're going to use OdinFlex again to process

the AR file which will give us access to all of the Mach-O files stored inside.

Those Mach-O files also have debugging sections that contain DWARF data, and

we'll use WORF to parse that data:

```ruby

File.open(archive) do |f|

  ar = OdinFlex::AR.new f

  ar.each do |object_file|

    next unless object_file.identifier =~ /\.o$/

    p object_file.identifier

    mach_o = OdinFlex::MachO.new(f)

    debug_abbrev = debug_strs = debug_info = nil

    mach_o.each do |part|

      if part.section?

        case part.sectname

        when "__debug_abbrev"

          debug_abbrev = WORF::DebugAbbrev.new f, part, mach_o.start_pos

        when "__debug_str"

          debug_strs = WORF::DebugStrings.new f, part, mach_o.start_pos

        when "__debug_info"

          debug_info = WORF::DebugInfo.new f, part, mach_o.start_pos

        end

      end

    end

    if debug_abbrev && debug_strs && debug_info

      puts "great"

      process_debug_info(debug_abbrev, debug_strs, debug_info)

      ## Now process the DWARF info

    end

    exit

  end

end

```

Now we can process the DWARF information and find holes in structs!

Ok, I am feeling lazy and don't want to write the rest of this program.

Check in the examples folder for a full listing.