busybox/scripts/trylink

#!/bin/sh

debug=false

try() {
    added="$1"
    shift
    $debug && echo "Trying: $* $added"
    "$@" $added >busybox.map 2>busybox_ld.err
}

# Sanitize lib list (dups, extra spaces etc)
#echo "BBOX_LIB_LIST=$BBOX_LIB_LIST"
BBOX_LIB_LIST=`echo "$BBOX_LIB_LIST" | xargs -n1 | sort | uniq | xargs`

# First link with all libs. If it fails, bail out
l_list=`echo "$BBOX_LIB_LIST" | sed -e 's/ / -l/g' -e 's/^/-l/'`
echo "Trying libraries: $BBOX_LIB_LIST"
try "-Wl,--start-group $l_list -Wl,--end-group" "$@" \
|| {
    echo "Failed: $* -Wl,--start-group $l_list -Wl,--end-group"
    cat busybox_ld.err
    exit 1
}
# Hack: we are not supposed to know executable name,
# but this hack cuts down link time
mv busybox_unstripped busybox_unstripped.tmp
mv busybox.map        busybox.map.tmp

# Now try to remove each lib and build without it.
# Stop when no lib can be removed.
ever_discarded=false
while test "$BBOX_LIB_LIST"; do
    $debug && echo "Trying libraries: $BBOX_LIB_LIST"
    all_needed=true
    for one in $BBOX_LIB_LIST; do
	without_one=`echo " $BBOX_LIB_LIST " | sed "s/ $one / /g" | xargs`
	l_list=`echo "$without_one" | sed -e 's/ / -l/g' -e 's/^/-l/'`
	$debug && echo "Trying -l options: $l_list"
	if try "-Wl,--start-group $l_list -Wl,--end-group" "$@"; then
		echo "Library $one is not needed"
		BBOX_LIB_LIST="$without_one"
		all_needed=false
		ever_discarded=true
	else
		echo "Library $one is needed"
	fi
    done
    # All libs were needed, can't remove any
    $all_needed && break
    # If there is no space char, the list has just one lib.
    # I'm not sure that in this case lib really is 100% needed.
    # Let's try linking without it anyway... thus commented out.
    #{ echo "$BBOX_LIB_LIST" | grep -q ' '; } || break
done

mv busybox_unstripped.tmp busybox_unstripped
mv busybox.map.tmp        busybox.map
$ever_discarded && {
    # Make the binary with final, minimal list of libs
    echo "Final link with: $BBOX_LIB_LIST"
    l_list=`echo "$BBOX_LIB_LIST" | sed -e 's/ / -l/g' -e 's/^/-l/'`
    try "-Wl,--start-group $l_list -Wl,--end-group" "$@" && exit 1
}
rm busybox_ld.err
exit 0  # Ensure "success" exit code