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# functions

Python repository containing parsed standard C library function and argument information
Python repository containing parsed standard C library function and argument information.
See `Example usage` section to see if it may help you.

## How do I use it?

I already did the heavy lifting for you, just look at [functions.py][1].
I already built it for you, just look at [functions.py](functions.py).

If you want to build it yourself, just clone the repo and `make clean all`.
If you want to build `functions.py` yourself, just clone the repo and fire `make clean all`.

Things will probably blow up, which is why I included a `Dockerfile`. You can build with `make release`.
Things will probably blow up, which is why I included a `Dockerfile`.
You can build `functions.py` with a simple `make release`.

[1]: https://github.com/zachriggle/functions/blob/master/functions.py
Note that it will build a docker image `functions` on your machine using the [Dockerfile](docker/Dockerfile) present in repo that is based on [pwntools/pwntools](https://hub.docker.com/r/pwntools/pwntools) docker image.

## Example
## Example usage

```
>>> from functions import functions
Expand All @@ -28,8 +30,14 @@ void
1
```

## Notes
## Notes aka how it works

Basically we just pass everything to `PyCParser` and extract all functions and arguments, as well as their types.
We keep a list of includes in [source.c](source.c). This file is then passed to GCC's preprocessor (`gcc -E` flag) so we get a `source.o` file that contains the content of all included headers (it is not really an object file).

We also keep a list of missing functions in `missing.txt`. Those functions are not present in the listed headers. We fetch their declarations from `man` pages using `missing.sh` and create `missing.h` header.

Later, we concatenate both files: `source.o` and `missing.h` into `preprocesed.h` file.

Finally, we just pass everything (`preprocessed.h` file) to [PyCParser](https://github.com/eliben/pycparser) and extract all functions and arguments, as well as their types.

Some syscalls are not in any standard C headers, so these have been added to `missing.txt`. The signatures are manually (pun!) extracted from the man pages.