From 150d2fa114d626761a67e529959433226793e733 Mon Sep 17 00:00:00 2001
From: Denis Vlasenko <vda.linux@googlemail.com>
Date: Tue, 17 Jul 2007 20:39:27 +0000
Subject: [PATCH] Modify method of linking against libs. Now we fisrt try all
 specified libs, and if it succeeds, we try to remove them one-by-one. If link
 succeeds, then library is thrown out. Should solve the problem with SELinux
 linking in libsepol even when not needed.

---
 Makefile.flags  | 13 ++++++++++---
 scripts/trylink | 52 +++++++++++++++++++++++++++++++++++++++++--------
 2 files changed, 54 insertions(+), 11 deletions(-)

diff --git a/Makefile.flags b/Makefile.flags
index b54679047..d8817bed6 100644
--- a/Makefile.flags
+++ b/Makefile.flags
@@ -59,18 +59,25 @@ ifeq ($(CONFIG_STATIC),y)
 LDFLAGS += -static
 endif
 
+BBOX_LIB_LIST = m crypt
 ifeq ($(CONFIG_SELINUX),y)
-LDLIBS += -lselinux -lsepol
+#LDLIBS += -lselinux -lsepol
+BBOX_LIB_LIST += selinux sepol
 endif
 
 ifeq ($(CONFIG_EFENCE),y)
-LDLIBS += -lefence
+#LDLIBS += -lefence
+BBOX_LIB_LIST += efence
 endif
 
 ifeq ($(CONFIG_DMALLOC),y)
-LDLIBS += -ldmalloc
+#LDLIBS += -ldmalloc
+BBOX_LIB_LIST += dmalloc
 endif
 
+# For scripts/trylink
+export BBOX_LIB_LIST
+
 #LDFLAGS += -nostdlib
 
 LDFLAGS_ELF2FLT = -Wl,-elf2flt
diff --git a/scripts/trylink b/scripts/trylink
index 52931b01c..ddd7fb179 100755
--- a/scripts/trylink
+++ b/scripts/trylink
@@ -6,13 +6,49 @@ try() {
     added="$1"
     shift
     $debug && echo "Trying: $* $added"
-    "$@" $added >busybox.map 2>busybox_ld.err \
-    && { rm busybox_ld.err; exit 0; }
+    "$@" $added >busybox.map 2>busybox_ld.err
 }
 
-try "" "$@"
-try "-lm" "$@"
-try "-lcrypt" "$@"
-try "-Wl,--start-group -lcrypt -lm -Wl,--end-group" "$@"
-# It failed. Let people see the error messages
-cat 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 $l_list -Wl,--end-group"
+    cat busybox_ld.err
+    exit 1
+}
+
+# Now try to remove each lib and build without.
+# Stop when no lib can be removed.
+while test "$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
+	else
+		echo "Library $one is needed"
+	fi
+    done
+    # All libs were needed, can't remove any
+    $all_needed && break
+    # If there is no space, the list has just one lib.
+    # I'm not sure that in this case lib really is 100% needed.
+    # Let's try linking without it anyway... thus commented out.
+    #echo "$BBOX_LIB_LIST" | grep -q ' ' || break
+done
+
+# Ok, make the binary
+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 $l_list -Wl,--end-group" "$@"