pre-build.sh

#!/usr/bin/env bash
# pre-build.sh: setup commands to run before building anything.
# Invoked by the Makefile automatically.
# If this script fails, the build will fail.
set -e

# We don't want to put dependency checks here because we run before `make
# get-deps` can do any dep-getting.

if which protoc >/dev/null 2>&1 && [ -e include/vg/vg.pb.h ] ; then
    HEADER_VER=$(cat include/vg/vg.pb.h | grep '\(GOOGLE_\)\?PROTOBUF_VERSION' | sed 's/[^0-9]*\([0-9]*\)[^0-9]*/\1/' | head -n1)
    if [ -z "${HEADER_VER}" ] ; then
        echo "Could not determine Protobuf version of existing generated headers."
        echo "Update pre-build.sh to understand Google's new format, or remove include/vg/vg.pb.h if it is not just a new format of generated code."
        exit 1
    fi
    WORKDIR=$(pwd)
    TESTDIR=$(mktemp -d)
    echo 'syntax = "proto3";' > ${TESTDIR}/empty.proto
    protoc ${TESTDIR}/empty.proto --proto_path=${TESTDIR} --cpp_out=${TESTDIR}
    PROTOC_VER=$(cat ${TESTDIR}/empty.pb.h | grep '\(GOOGLE_\)\?PROTOBUF_VERSION' | sed 's/[^0-9]*\([0-9]*\)[^0-9]*/\1/' | head -n1)
    if [ "${HEADER_VER}" != "${PROTOC_VER}" ] ; then
        echo "Protobuf version has changed!"
        echo "Headers are for ${HEADER_VER} but we make headers for ${PROTOC_VER}"
        echo "Need to rebuild libvgio"
        rm -f lib/libvgio.a
        rm -f include/vg/vg.pb.h
    fi
    rm ${TESTDIR}/empty.proto ${TESTDIR}/empty.pb.h ${TESTDIR}/empty.pb.cc
    rmdir ${TESTDIR}
fi;

# A note about Protobuf:
# We have a lot of logic here to make sure that the protoc we have generates headers with exactly the same
# version requirements as the headers we already have.
# If not, we regenerate them.
# Doesn't handle Protobuf 3.12.3 weirdness; just make clean if you change flavors of Protobuf 3.12.3.