configure

#!/bin/sh
# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
#
# create the makevars for unix like systems (tested on debian and ubuntu)
#
# NOTES:
# The system variable USESPECIALPYTHONVERSION can be used to link to a special
# python version. 
# export USESPECIALPYTHONVERSION="python3.4"
# it can be very usefull especially for testing but one has to ensure  that
# the file PYVERSION-config is present at the provided location else it will
# fail.
# But when using python3 also python3-dev has to be installed 
# (apt-get install python3-dev)
# 
# gcc:
# there seems to be a new option which doesn't allows me to compile
# -fstack-protector-strong so I just remove it
# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# exit immediately if any step fails
set -e

# ----- install the Python package -----
EMBED_PYTHON_VERSION=3.6
EMBED_PYTHON_VERSION_EXTENDED=${EMBED_PYTHON_VERSION}.8
PYTHON_ARCHIVE_NAME=Python-${EMBED_PYTHON_VERSION_EXTENDED}
PYTHON_RUNTIME_BUNDLE=https://www.python.org/ftp/python/${EMBED_PYTHON_VERSION_EXTENDED}/${PYTHON_ARCHIVE_NAME}.tgz

cd inst
# don't halt the script if wget is not found, just switch to curl
set +e
wget -O ${PYTHON_ARCHIVE_NAME}.tgz ${PYTHON_RUNTIME_BUNDLE}
if [ "$?" -ne "0" ]; then
    curl -o ${PYTHON_ARCHIVE_NAME}.tgz ${PYTHON_RUNTIME_BUNDLE}
fi
if [ "$?" -ne "0" ]; then
  echo "Failed to download ${PYTHON_RUNTIME_BUNDLE}"
  exit 1
fi
# back to the exit-immediately-mode
set -e

tar -xzf ${PYTHON_ARCHIVE_NAME}.tgz
rm ${PYTHON_ARCHIVE_NAME}.tgz
EMBED_PYTHON_DIR=${PWD}
cd ${PYTHON_ARCHIVE_NAME}

if [ $(uname) == "Darwin" ]; then
  echo "Mac specific configuration"
  # When installing openssl on Mac there is a message:
  # For compilers to find this software you may need to set:
  #     LDFLAGS:  -L/usr/local/opt/openssl/lib
  #     CPPFLAGS: -I/usr/local/opt/openssl/include
  # export LDFLAGS=-L/usr/local/opt/openssl/lib

  # sdk path needed for zlib on catalina
  export CPPFLAGS="-I/usr/local/opt/openssl/include -I$(xcrun --show-sdk-path)/usr/include"

  # However the above isn't enough since the libraries have to be bundled into 
  # the package
  mkdir -p ${EMBED_PYTHON_DIR}/lib
  LIBCRYPTO_DYLIB_PATH=$(ls -a /usr/local/opt/openssl/lib/libcrypto.1*.dylib)
  LIBCRYPTO_DYLIB_FILENAME=$(basename $LIBCRYPTO_DYLIB_PATH)
  LIBSSL_DYLIB_PATH=$(ls -a /usr/local/opt/openssl/lib/libssl.1*.dylib)
  LIBSSL_DYLIB_FILENAME=$(basename $LIBSSL_DYLIB_PATH)

  cp /usr/local/opt/openssl/lib/libcrypto.a ${EMBED_PYTHON_DIR}/lib/
  cp $LIBCRYPTO_DYLIB_PATH ${EMBED_PYTHON_DIR}/lib/
  cp /usr/local/opt/openssl/lib/libssl.a ${EMBED_PYTHON_DIR}/lib/
  cp $LIBSSL_DYLIB_PATH ${EMBED_PYTHON_DIR}/lib/
  chmod u+w ${EMBED_PYTHON_DIR}/lib/*

  export LIBCRYPTO_LOAD_DYLIB_PATH=$(otool -L ${EMBED_PYTHON_DIR}/lib/$LIBSSL_DYLIB_FILENAME | grep libcrypto | cut -d" " -f1)
  # https://blogs.oracle.com/dipol/dynamic-libraries,-rpath,-and-mac-os
  install_name_tool -change \
  $LIBCRYPTO_LOAD_DYLIB_PATH \
  "@loader_path/$LIBCRYPTO_DYLIB_FILENAME" \
  ${EMBED_PYTHON_DIR}/lib/$LIBSSL_DYLIB_FILENAME

  # https://wiki.python.org/moin/BuildStatically
  # https://stackoverflow.com/questions/1150373/compile-the-python-interpreter-statically
  # errors occur when either of the following is enabled
  # echo $'*static*\n_ssl _ssl.c -DUSE_SSL ${CPPFLAGS} ${LDFLAGS} -lssl -lcrypto' >> Modules/Setup.local
  # echo $'_ssl _ssl.c -DUSE_SSL ${CPPFLAGS} ${LDFLAGS} -lssl -lcrypto' >> Modules/Setup.local
fi

# in the following line the '--prefix' parameter is the installation location
# NOTE: removed --enable-shared option and added CFLAGS=-fPIC CXXFLAGS=-fPIC to try to get a static library
./configure CFLAGS=-fPIC CXXFLAGS=-fPIC --prefix=${EMBED_PYTHON_DIR}
make
make altinstall
cd ..
rm -R ${PYTHON_ARCHIVE_NAME}
cd ..

# ensure that the embedded python interpreter has newer version of pip so that
# downstream package installations will have a better chance of installing precompiled wheels
${EMBED_PYTHON_DIR}/bin/python${EMBED_PYTHON_VERSION} -m pip install pip==21.0.1

# these exact paths vary by python version so use wildcard expansions to find the actual path
MYPYTHONCONFIG=$(ls ${EMBED_PYTHON_DIR}/bin/python${EMBED_PYTHON_VERSION}*-config)
MYPYTHONLIBDIR=$(ls -d ${EMBED_PYTHON_DIR}/lib/python${EMBED_PYTHON_VERSION}/*config-${EMBED_PYTHON_VERSION}*)

# Extract the linker and include flags for python
: ${PYTHONCONFIG=`which ${MYPYTHONCONFIG}`}
if test -z "${PYTHONCONFIG}"; then
  echo "could not locate ${MYPYTHONCONFIG}"
  exit 1
fi

echo "python version is ${EMBED_PYTHON_VERSION_EXTENDED}"
PYXY="PYTHONLIBXY=libpython${EMBED_PYTHON_VERSION}m.so"
PYLIBS="PKG_LIBS=-L$MYPYTHONLIBDIR "`$PYTHONCONFIG --libs`
PYCFLAGS="PKG_CFLAGS="`$PYTHONCONFIG --cflags`" -D $PYXY -D PYTHON_IN_R_NO_EXPLICIT_LINKING"

#clean up the old compilation or else it wont recompile
rm -f src/*.o src/*.so src/*.rds src/Makevars

echo ""
echo "Makevars:"
echo $PYLIBS
echo $PYCFLAGS | sed 's/Wstrict-prototypes/pedantic/' | sed 's/ -fstack-protector-strong//'
echo ""

# replacing Wstrict-prototypes removes some unnecessary warnings
echo $PYLIBS > src/Makevars
echo $PYCFLAGS | sed 's/Wstrict-prototypes/pedantic/' | sed 's/ -fstack-protector-strong//' >> src/Makevars