cnile: GCC-plugin to store build flags in the resulting binary file.

What

cnile is a plugin for GCC which stores the flags used for compiling. What's that you ask? How many times have you been presented with a binary or object file and asked the question: "Was this compiled using xyz flags?" Perhaps you forgot? Well, that day is over. This is a stupid-simple plugin which stashes all build flags in a separate section of the binary being compiled.

Related Works

ld' provides a --build-id flag gcc' provides -frecord-gcc-switches and -grecord-gcc-switches

Dependencies

GCC version 4.5 introduced plugins. cnile has only been built and tested on 4.8 thus, for older versions, your mileage might vary.

Build

This is a GCC plugin and uses the plugin framework built with g++ in version 4.8 of GCC. To build things simply run `make' from the cnile directory.

Use

Next time you build with GCC 4.8 or higher, include the cnile plugin by passing the '-fplugin=cnile.so' flag to GCC.

The flags are stored as comma separated values in the .cnile section of the binary. objdump' or 'strings' can be used to get the goodies out: objdump -j .cnile -s'

The section begins with the text: "" and ends with "". This permits trivial sed processing: strings <your binary> | sed '/<cnile>/,/<\/cnile/>'

objcopy' is also another good utility that can aid extracting just the .cnile section from the binary. For instance, an executable named 'foo' and the .cnile section extracted to 'foo.csv' objcopy -O binary --only-section=.cnile foo foo.csv'

Thanks to ndim over at: http://stackoverflow.com/questions/3925075/how-do-you-extract-only-the-contents-of-an-elf-section

Install

GCC must know where cnile.so is located in order to use it. You can install this plugin where GCC recognizes your other plugins by copying cnile.so there. The general plugin directory can be found by issuing the following argument to GCC: `gcc -print-file-name=plugin' You will still have to issue the '-fplugin=cnile.so' flag for the magic to get rockin'.

But wait, what's easier is that you can merely specify the full path to the plugin when you compile your program: `gcc foo.c -fplugin=/path/to/cnile.so'

Contact

Matt Davis (enferex) [email protected]