New script

git-svn-id: svn+ssh://svn.gna.org/svn/gnustep/tools/make/trunk@13373 72102866-910b-0410-8b05-ffd578937521

relative_path.sh

@@ -0,0 +1,123 @@
+#!/bin/sh
+# relative_path.sh
+#
+# Copyright (C) 2002 Free Software Foundation, Inc.
+#
+# Author: Nicola Pero <n.pero@mi.flashnet.it>
+# Date: April 2001
+#
+# This file is part of the GNUstep Makefile Package.
+#
+# This library is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License
+# as published by the Free Software Foundation; either version 2
+# of the License, or (at your option) any later version.
+# 
+# You should have received a copy of the GNU General Public
+# License along with this library; see the file COPYING.LIB.
+# If not, write to the Free Software Foundation,
+# 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+
+# This script gets two paths as argument - and outputs a relative path
+# which, when appended to the first one, gives the second one ... more
+# precisely, the path of minimum length with this property.
+#
+# for example,
+#
+# $GNUSTEP_MAKEFILES/relative_path.sh /usr/GNUstep/Local /usr/GNUstep/System
+#
+# returns ../System (and not ../../GNUstep/System which is not the minimum).
+#
+# This is needed by `ln -s' to properly create symlinks between
+# directories which are related ... but we don't know how.  We only
+# need this for frameworks, which are particularly complex and
+# delicate.  For example, to create the link
+#
+# /usr/GNUstep/System/Libraries/ix86/linux-gnu/gnu-gnu-gnu/libnicola.so
+#   --> ../../../../Frameworks/nicola.framework/Versions/Current/ix86/linux-gnu/gnu-gnu-gnu/libnicola.so
+#
+# (and where the paths are actually computed by make variables which
+# might depend on variables in user makefiles outside our control, so
+# it's not obvious what the relationship is between the two paths, and
+# you only have the absolute paths) we do -
+#
+# cd /usr/GNUstep/System/Libraries/ix86/linux-gnu/gnu-gnu-gnu/libnicola.so
+# $(LN_S) `$(RELATIVE_PATH_SCRIPT) /usr/GNUstep/System/Frameworks/nicola.framework/Versions/Current/ix86/linux-gnu/gnu-gnu-gnu/libnicola.so /usr/GNUstep/System/Libraries/ix86/linux-gnu/gnu-gnu-gnu/`
+#
+# which creates the link.  We need to use the minimum path because
+# that is the most relocatable possible path.  I consider all this a
+# trick and a hack and recommend to use libraries and bundles instead
+# of frameworks, since libraries and bundles are much more portable
+# and stable, anyway here we are.
+
+if [ "$#" != 2 ]; then
+  exit 1
+fi
+
+a="$1";
+b="$2";
+
+if [ "$a" = "" ]; then
+  exit 1
+fi
+
+if [ "$b" = "" ]; then
+  exit 1
+fi
+
+
+#
+# Our first argument is a path like /xxx/yyy/zzz/ccc/ttt
+# Our second argument is a path like /xxx/yyy/kkk/nnn/ppp
+#
+
+# We first want to remove the common root -- we want to get into having
+# /zzz/ccc/tt and /kkk/nnn/ppp.
+
+# We first try to match as much as possible between the first and the second
+# So we loop on the fields in the second
+tmp_IFS="$IFS"
+IFS=/
+partial_b=""
+partial_match=""
+for component in $b; do
+  if [ -n "$component" ]; then
+    partial_b="$partial_b/$component"
+    case "$a" in
+      "$partial_b"*) partial_match="$partial_b";;
+      *) break;;
+    esac
+  fi
+done
+IFS="$tmp_IFS"
+
+# Now partial_match is the substring which matches (/xxx/yyy/) in the
+# example.  Remove it from both a and b.
+a=$(echo $a | sed -e "s#$partial_match##")
+b=$(echo $b | sed -e "s#$partial_match##")
+
+# Ok - now ready to build the result
+result=""
+
+# First add as many ../ as there are components in a
+tmp_IFS="$IFS"
+IFS=/
+for component in $a; do
+  if [ -n "$component" ]; then
+    if [ -z "$result" ]; then
+      result=".."
+    else
+      result="$result/.."
+    fi
+  fi
+done
+IFS="$tmp_IFS"
+
+# Then, append b
+if [ -n "$result" ]; then
+  result="$result$b"
+else
+  result="$b"
+fi
+
+echo "$result"