Analyses

Clearly we don't want our users to write the model by hand. Therefore, as mentioned before, we developed a series of analyses which can automatically populate the model for you when you open a new project.

Consider the following simple program:

example.c

int main(int argc, char *argv[]) {
  return argc * 3;
}

Let's compile it:

$ gcc example.c -o example -O2

We can use the import-binary analysis to automatically collect all the loading information available in the ELF headers:

$ revng analyze import-binary example -o example.yml
$ grep -A7 'Segments:' example.yml
Segments:
  - StartAddress:    "0x400000:Generic64"
    VirtualSize:     2528
    StartOffset:     0
    FileSize:        2528
    IsReadable:      true
    IsWriteable:     false
    IsExecutable:    true

However, the typical workflow does not require the user to manually specify what analyses to run, but there's a set of predefined analyses that should be run on a new project, the initial autoanalyses.

$ revng analyze \
        --resume=working-directory  \
        revng-initial-auto-analysis  \
        example  \
        -o /dev/null
$ revng analyze \
        --resume=working-directory  \
        revng-c-initial-auto-analysis  \
        example  \
        -o /dev/null
$ revng artifact \
        --resume working-directory \
        decompile-to-single-file \
        example \
        | revng ptml | grep -A2 -B1 '\bmain\b'
_ABI(SystemV_x86_64)
generic64_t main(generic64_t _argument0) {
  return _argument0 * 3 & 0xFFFFFFFF;
}

The commands above are stateful, they build on top of each other storing intermediate results into the directory specified by the --resume parameter. The first command runs the set of initial autoanalyses of revng, the open source component of rev.ng, the second the analyses of revng-c, in particular Data LayoutAnalysis, and the last one produces the decompiled code.

Alternatively, you can run revng-initial-auto-analysis and revng-c-initial-auto-analysis above and produce the artifact with a single command:

$ revng artifact \
        --analyze \
        decompile-to-single-file \
        example \
        | revng ptml \
        | grep -A2 -B1 '\bmain\b'
_ABI(SystemV_x86_64)
generic64_t main(generic64_t _argument0) {
  return _argument0 * 3 & 0xFFFFFFFF;
}