Compiling Apache on Ubuntu

On a clean 16.04 server machine I will build apache. Desktop instructions should be no different.

>more /etc/lsb-release

DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=16.04
DISTRIB_CODENAME=xenial
DISTRIB_DESCRIPTION="Ubuntu 16.04 LTS"

Step 1.

Install wllvm

>sudo apt-get update

>sudo install python-pip

>sudo pip install wllvm

I am only going to build apache, not apr, so I first install the prerequisites.

>sudo apt-get install llvm clang libapr1-dev libaprutil1-dev libpcre3-dev make

At this point, you could check your clang version with which clang and ls -l /usr/bin/clang. It should be at least clang-3.8.

Configure the wllvm tool to use clang and be relatively quiet:

>export LLVM_COMPILER=clang

>export WLLVM_OUTPUT=WARNING

Fetch apache, untar, configure, then build:


>wget https://archive.apache.org/dist/httpd/httpd-2.4.23.tar.gz

>tar xfz httpd-2.4.23.tar.gz

>cd httpd-2.4.23

>CC=wllvm ./configure

>make

Extract the bitcode.

>extract-bc httpd

>ls -la httpd.bc
-rw-r--r-- 1 vagrant vagrant 1119584 Aug  4 20:02 httpd.bc

Note that in httpd-2.4.41, the binary of httpd is under directory ".libs", > in that case, please cd into ".libs" then execute the command.

cd .libs
ls -la httpd
extract-bc httpd

Turn the bitcode into a second executable binary. (optional -- just for fun and sanity checking)

llc -filetype=obj httpd.bc
clang httpd.o  -Wl,--export-dynamic -lpthread -lapr-1 -laprutil-1 -lpcre -o httpd_from_bc

See here for an explanation of the

-Wl,--export-dynamic

incantation.