configure

#!/bin/sh

# Look for a system libzstd. If a suitable one is not found, use the
# bundled copy in src/libzstd.
#
# Environment variables:
# - ZSTD_BUNDLED=true: always use the bundled libzstd.
# - ZSTD_CFLAGS, ZSTD_LIBS: compiler and linker flags for a system libzstd,
#   these are used instead of pkg-config.

: ${R_HOME=`R RHOME`}
if test -z "${R_HOME}"; then
  echo "could not determine R_HOME"
  exit 1
fi

# libzstd 1.5.0 added ZSTD_defaultCLevel()
MIN_VERSION=1.5.0
MIN_VERSION_NUMBER=10500

RBIN="${R_HOME}/bin/R"
CC=`"${RBIN}" CMD config CC`
CPPFLAGS=`"${RBIN}" CMD config CPPFLAGS`
CFLAGS=`"${RBIN}" CMD config CFLAGS`
LDFLAGS=`"${RBIN}" CMD config LDFLAGS`

use_bundled() {
  echo "** using bundled libzstd"
  PKG_CPPFLAGS="-Ilibzstd -DZSTD_R_BUNDLED"
  PKG_LIBS="-lpthread"
  PKG_OBJECTS="libzstd/zstd.o"
}

check_system() {
  echo "** checking system libzstd with flags: $1 $2"
  tmpdir=`mktemp -d 2>/dev/null || echo "${TMPDIR:-/tmp}/zstd-conf-$$"`
  mkdir -p "$tmpdir"
  cat > "$tmpdir/conftest.c" <<EOF
#define ZSTD_STATIC_LINKING_ONLY
#include <zstd.h>
#include <zdict.h>
#if ZSTD_VERSION_NUMBER < ${MIN_VERSION_NUMBER}
#error libzstd is too old
#endif
int main(void) {
  ZSTD_frameHeader fh;
  (void) ZSTD_getFrameHeader(&fh, 0, 0);
  (void) ZDICT_isError(0);
  (void) ZSTD_defaultCLevel();
  /* headers and library must be the same version */
  return ZSTD_versionNumber() != ZSTD_VERSION_NUMBER;
}
EOF
  # Same flag order as R uses when building the package
  ${CC} $1 ${CPPFLAGS} ${CFLAGS} "$tmpdir/conftest.c" -o "$tmpdir/conftest" \
    ${LDFLAGS} $2 >/dev/null 2>&1 && "$tmpdir/conftest"
  status=$?
  rm -rf "$tmpdir"
  return $status
}

if test "${ZSTD_BUNDLED}" = "true"; then
  use_bundled
else
  found=false
  if test -n "${ZSTD_CFLAGS}${ZSTD_LIBS}"; then
    cand_cflags="${ZSTD_CFLAGS}"
    cand_libs="${ZSTD_LIBS:--lzstd}"
    if check_system "$cand_cflags" "$cand_libs"; then found=true; fi
  else
    if pkg-config --version >/dev/null 2>&1 &&
       pkg-config --atleast-version=${MIN_VERSION} libzstd 2>/dev/null; then
      cand_cflags=`pkg-config --cflags libzstd`
      cand_libs=`pkg-config --libs libzstd`
      if check_system "$cand_cflags" "$cand_libs"; then
        found=true
      else
        cand_libs=`pkg-config --libs --static libzstd`
        if check_system "$cand_cflags" "$cand_libs"; then found=true; fi
      fi
    fi
    if test "$found" = "false"; then
      cand_cflags=""
      cand_libs="-lzstd"
      if check_system "$cand_cflags" "$cand_libs"; then found=true; fi
    fi
  fi

  if test "$found" = "true"; then
    echo "** using system libzstd"
    PKG_CPPFLAGS="$cand_cflags"
    PKG_LIBS="$cand_libs"
    PKG_OBJECTS=""
  else
    echo "** no suitable system libzstd (>= ${MIN_VERSION}) found"
    use_bundled
  fi
fi

sed -e "s|@cppflags@|${PKG_CPPFLAGS}|" \
    -e "s|@libs@|${PKG_LIBS}|" \
    -e "s|@objects@|${PKG_OBJECTS}|" \
    src/Makevars.in > src/Makevars

exit 0