Create relative symlinks in /lib/initd

It's nice to create relative symlinks from /lib/initd to /sbin so that
the link path is always correct no matter where the filesystems are
mounted. To accomplish this, a script abs2rel.sh has been added which
converts two directory paths to a relative path. This is used to find
the relative path between /lib/initd and /sbin.

3 files changed, 94 insertions, 6 deletions

diff --git a/Makefile.am b/Makefile.am
index 128d61e..1f08a70 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -1 +1,3 @@
 SUBDIRS = lib src test
+
+dist_noinst_SCRIPTS = abs2rel.sh
diff --git a/abs2rel.sh b/abs2rel.sh
new file mode 100755
index 0000000..224cbb7
--- /dev/null
+++ b/abs2rel.sh
@@ -0,0 +1,83 @@
+#!/bin/sh
+
+# Determine the relative path between 2 directories. This is modeled
+# on the perl File::Spec abs2rel function.
+
+if test "x$1" = x || test "x$2" = x; then
+	echo "error: two paths must be supplied to $0" >&2
+	exit 1
+fi
+
+dir1=$1
+dir2=$2
+
+# all shell builtins except for sed; let user override
+SED=${SED-sed}
+
+# if either path is not absolute, prefix the current directory
+case "$dir1" in
+/*) ;;
+*)  dir1=$PWD/$dir1 ;;
+esac
+case "$dir2" in
+/*) ;;
+*)  dir2=$PWD/$dir2 ;;
+esac
+
+# strip multiple / and trailing /
+dir1=`echo $dir1 | $SED 's,//*,/,g;s,\(.\)/$,\1,'`
+dir2=`echo $dir2 | $SED 's,//*,/,g;s,\(.\)/$,\1,'`
+
+# special cases
+if test "$dir1" = "$dir2"; then
+	# same directory, no relative path needed
+	exit 0
+elif test "$dir1" = /; then
+	# convert all components of $2 to ..
+	dir2=`echo $dir2 | $SED 's,/[^/]*,../,g'`
+	echo ${dir2%/}
+	exit 0
+elif test "$dir2" = /; then
+	# strip leading / of $1 to convert to relative
+	echo ${dir1#/}
+	exit 0
+fi
+
+# find the common prefix
+pre1=
+pre2=
+while :; do
+	# find the leading dir component
+	pre1=${dir1#/}
+	pre1=/${pre1%%/*}
+	pre2=${dir2#/}
+	pre2=/${pre2%%/*}
+
+	# if the leading components match, strip them from the suffixes
+	if test "$pre1" = "$pre2"; then
+		dir1=${dir1#$pre1}
+		dir2=${dir2#$pre2}
+
+		# if either suffix is empty, we're done
+		if test "x$dir1" = x; then
+			break
+		elif test "x$dir2" = x; then
+			# dir1 is a subdir of dir2; convert to relative
+			dir1=${dir1#/}
+			break
+		fi
+	else
+		# we've found the common prefix
+		break
+	fi
+done
+
+# convert remaining components of $dir2 to ..
+rem=
+if test "x$dir2" != x; then
+	rem=`echo $dir2 | $SED 's,/[^/]*,../,g'`
+	rem=${rem%/}
+fi
+
+# print converted $dir2 + remainder of $dir1
+echo $rem$dir1
diff --git a/src/Makefile.am b/src/Makefile.am
index 3fb14c5..0b38199 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -14,12 +14,15 @@ man_MANS = install_initd.8 remove_initd.8
 libinitddir = $(exec_prefix)/lib/initd
 install-exec-hook:
 	$(MKDIR_P) $(DESTDIR)$(libinitddir)
-	rm -f $(DESTDIR)$(libinitddir)/install_initd
-	$(LN_S) $(sbindir)/install_initd \
-	  $(DESTDIR)$(libinitddir)/install_initd
-	rm -f $(DESTDIR)$(libinitddir)/remove_initd
-	$(LN_S) $(sbindir)/remove_initd \
-	  $(DESTDIR)$(libinitddir)/remove_initd
+	@relpath=`$(SHELL) $(top_srcdir)/abs2rel.sh $(sbindir) $(libinitddir)` \
+	  || relpath=$(sbindir); \
+	for prog in install_initd remove_initd; do \
+	  echo rm -f $(DESTDIR)$(libinitddir)/$$prog && \
+	  rm -f $(DESTDIR)$(libinitddir)/$$prog && \
+	  echo $(LN_S) $$relpath/$$prog $(DESTDIR)$(libinitddir)/$$prog && \
+	  $(LN_S) $$relpath/$$prog $(DESTDIR)$(libinitddir)/$$prog \
+	  || exit $?; \
+	done
 
 uninstall-hook:
 	rm -f $(DESTDIR)$(libinitddir)/install_initd