gistfile1.sh

#!/usr/bin/env bash

if [ -z "$HOSTPREFIX" ]; then
  PLATFORM=$(uname -s)
  
  if [[ $PLATFORM == *NT* ]] || [[ $PLATFORM == *WIN* ]]; then
    HOSTPREFIX=i686-w64-mingw32
  fi
fi

if [ -z "$SYMBOLS_TO_EXPORT" -o $# -eq 0 ]; then
  echo -n "usage: SYMBOLS_TO_EXPORT=\"sym1 *sym2*, ...\" [HOSTPREFIX=...]"
  echo "$0 obj1.o obj2.o ..."
  exit 1
fi

SYMBOLS_TO_EXPORT=${SYMBOLS_TO_EXPORT//\"/}

if [[ $HOSTPREFIX == *mingw* ]]; then
  LLVM_NM="llvm-nm"
  LLVM_DIS="llvm-dis"

  NM=$(which $LLVM_NM 2>/dev/null || which $HOSTPREFIX-nm 2>/dev/null || \
       echo "nm")

  SYMBOLS=""

  for obj in $*; do
    X86=0
    FILETYPE=$(file $obj)
    
    if [[ $FILETYPE == *LLVM\ IR\ bitcode* ]]; then
      [[ $($LLVM_DIS $obj && cat $obj.ll | grep "target triple =" | head -n1 ;
         rm $obj.ll) == *i*86* ]] && X86=1
    else
      [[ $FILETYPE == *80386* ]] && X86=1
    fi 
    
    if [ $X86 -eq 1 ] || [[ $NM == *$LLVM_NM ]]; then
      if [ $X86 -eq 1 ]; then
        CHARSTOSKIP=13
      else
        CHARSTOSKIP=12
      fi
    else
      CHARSTOSKIP=20
    fi

    OBJSYMBOLS=$($NM $obj --defined-only | grep -E " T | B " | \
                 cut -c ${CHARSTOSKIP}-)

    SYMBOLS+=" $OBJSYMBOLS"
  done
  
  DEF="EXPORTS"

  for symbol in $SYMBOLS; do
    for symbol_to_export in ${SYMBOLS_TO_EXPORT//\*/\?}; do
      eval "[[ "$symbol" == ${symbol_to_export//\?/\*} ]]"
      if [ $? -eq 0 ]; then
        DEF+=$'\n'"$symbol"
        break
      fi
    done
  done

  echo "$DEF" > tmp.def
  echo "tmp.def"
else
  VERSCRIPT="{"$'\n'
  
  VERSCRIPT+="global:"$'\n'

  for symbol_to_export in ${SYMBOLS_TO_EXPORT//\*/\?}; do
    VERSCRIPT+="    ${symbol_to_export//\?/\*};"$'\n'
  done
  
  VERSCRIPT+="local:"$'\n'"   *;"$'\n'

  VERSCRIPT+="};"
  echo $VERSCRIPT > tmp.exports
  echo "-Wl,--version-script=tmp.exports"
fi