README.rst

Prerequisites

OCCAM currently works fine on Linux, OS X, and FreeBSD. You will need an installation of llvm-3.5. If you need to generate application bitcode, you will want to install wllvm, either from the the pip package or the GitHub repository.

Building and Installing

Set where OCCAM's library will be stored:

export OCCAM_HOME={path to location in your home directory}

Point to your LLVM's location, if non-standard:

export LLVM_HOME=/usr/local/llvm-3.5
export LLVM_CONFIG=llvm-config-3.5

Set where system libraries, including Google Protocol Buffers, are located:

export LD_FLAGS='-L/usr/local/lib'

Build and install OCCAM with:

make
make install

Using OCCAM

You can choose to record logs from the OCCAM tool by setting the following variables:

export OCCAM_LOGFILE={absolute path to log location}
export OCCAM_LOGLEVEL={INFO, WARNING, or ERROR}

Using razor

razor is a pip package that relies on the same dynamic library as occam, so you should first build and install occam as described above. You can install it from this repository, or you can just do a

pip install razor

To install and editable version from this repository:

make -f Makefile develop

This may require sudo priviliges. Either way you can now use slash:

slash [--work-dir=<dir>]  [--force] [--no-strip] [--no-specialize] <manifest>

slash also accepts the following new command line option:

--no-specialize

which will prevent any inter-module specializations.

The Manifest(o)

The manifest for slash should be valid JSON. The following keys have meaning:

• main : a path to the bitcode module containing the main entry point.
• modules: a list of paths to the other bitcode modules needed.
• binary : the name of the desired executable.
• native_libs : a list of flags (-lm, -lc, -lpthread) or paths to native objects (.o, .a, .so, .dylib)
• ldflags: a list of linker flags such as --static, --nostdlib
• args : the list of arguments you wish to specialize in the main of main.

As an example, (see examples/linux/apache), to previrtualize apache:

{ "main" : "httpd.bc"
, "binary"  : "httpd_slashed"
, "modules"    : ["libapr-1.so.bc", "libaprutil-1.so.bc", "libpcre.so.bc"]
, "native_libs" : ["-lcrypt", "-ldl", "-lpthread"]
, "args"    : ["-d", "/var/www"]
, "name"    : "httpd"
}

Another example, (see examples/linux/musl_nweb), specializes nweb with musl libc.c:

{ "main" :  "nweb.o.bc"
, "binary"  : "nweb_razor"
, "modules"    : ["libc.a.bc"]
, "native_libs" : ["crt1.o", "libc.a"]
, "ldflags" : ["-static", "-nostdlib"]
, "args"    : ["8181", "./root"]
, "name"    : "nweb"
}