311 lines
8.8 KiB
Bash
Executable File
311 lines
8.8 KiB
Bash
Executable File
#!/bin/sh
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debug=false
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# Linker flags used:
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#
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# Informational:
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# --warn-common
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# -Map $EXE.map
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# --verbose
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#
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# Optimizations:
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# --sort-common reduces padding
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# --sort-section alignment reduces padding
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# --gc-sections throws out unused sections,
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# does not work for shared libs
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# -On Not used, maybe useful?
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#
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# List of files to link:
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# $l_list == --start-group -llib1 -llib2 --end-group
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# --start-group $O_FILES $A_FILES --end-group
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#
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# Shared library link:
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# -shared self-explanatory
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# -fPIC position-independent code
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# --enable-new-dtags ?
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# -z,combreloc ?
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# -soname="libbusybox.so.$BB_VER"
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# --undefined=lbb_main Seed name to start pulling from
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# (otherwise we'll need --whole-archive)
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# -static Not used, but may be useful! manpage:
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# "... This option can be used with -shared.
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# Doing so means that a shared library
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# is being created but that all of the library's
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# external references must be resolved by pulling
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# in entries from static libraries."
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try() {
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printf "%s\n" "Output of:" >$EXE.out
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printf "%s\n" "$*" >>$EXE.out
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printf "%s\n" "==========" >>$EXE.out
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$debug && echo "Trying: $*"
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$@ >>$EXE.out 2>&1
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return $?
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}
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check_cc() {
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local tempname="/tmp/temp.$$.$RANDOM"
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# Can use "-o /dev/null", but older gcc tend to *unlink it* on failure! :(
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# "-xc": C language. "/dev/null" is an empty source file.
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if $CC $1 -shared -xc /dev/null -o "$tempname".o >/dev/null 2>&1; then
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echo "$1";
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else
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echo "$2";
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fi
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rm "$tempname".o 2>/dev/null
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}
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check_libc_is_glibc() {
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local tempname="/tmp/temp.$$.$RANDOM"
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echo "\
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#include <stdlib.h>
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/* Apparently uclibc defines __GLIBC__ (compat trick?). Oh well. */
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#if defined(__GLIBC__) && !defined(__UCLIBC__)
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syntax error here
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#endif
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" >"$tempname".c
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if $CC "$tempname".c -c -o "$tempname".o >/dev/null 2>&1; then
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echo "$2";
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else
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echo "$1";
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fi
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rm "$tempname".c "$tempname".o 2>/dev/null
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}
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EXE="$1"
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CC="$2"
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CFLAGS="$3"
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LDFLAGS="$4"
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O_FILES="$5"
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A_FILES="$6"
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LDLIBS="$7"
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# The --sort-section option is not supported by older versions of ld
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SORT_SECTION=`check_cc "-Wl,--sort-section,alignment" ""`
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START_GROUP="-Wl,--start-group"
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END_GROUP="-Wl,--end-group"
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INFO_OPTS="-Wl,--warn-common -Wl,-Map,$EXE.map -Wl,--verbose"
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# gold may not support --sort-common (yet)
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SORT_COMMON=`check_cc "-Wl,--sort-common" ""`
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# Static linking against glibc produces buggy executables
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# (glibc does not cope well with ld --gc-sections).
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# See sources.redhat.com/bugzilla/show_bug.cgi?id=3400
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# Note that glibc is unsuitable for static linking anyway.
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# We are removing -Wl,--gc-sections from link command line.
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GC_SECTIONS=`(
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. ./.config
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if test x"$CONFIG_STATIC" = x"y"; then
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check_libc_is_glibc "" "-Wl,--gc-sections"
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else
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echo "-Wl,--gc-sections"
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fi
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)`
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# The --gc-sections option is not supported by older versions of ld
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if test -n "$GC_SECTIONS"; then
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GC_SECTIONS=`check_cc "$GC_SECTIONS" ""`
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fi
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# Sanitize lib list (dups, extra spaces etc)
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LDLIBS=`echo "$LDLIBS" | xargs -n1 | sort | uniq | xargs`
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# First link with all libs. If it fails, bail out
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echo "Trying libraries: $LDLIBS"
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# "lib1 lib2 lib3" -> "-llib1 -llib2 -llib3"
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l_list=`echo " $LDLIBS " | sed -e 's: \([^- ][^ ]*\): -l\1:g'`
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test "x$l_list" != "x" && l_list="$START_GROUP $l_list $END_GROUP"
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try $CC $CFLAGS $LDFLAGS \
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-o $EXE \
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$SORT_COMMON \
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$SORT_SECTION \
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$GC_SECTIONS \
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$START_GROUP $O_FILES $A_FILES $END_GROUP \
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$l_list \
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|| {
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echo "Failed: $l_list"
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cat $EXE.out
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exit 1
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}
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# Now try to remove each lib and build without it.
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# Stop when no lib can be removed.
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while test "$LDLIBS"; do
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$debug && echo "Trying libraries: $LDLIBS"
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all_needed=true
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last_needed=false
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for one in $LDLIBS; do
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without_one=`echo " $LDLIBS " | sed "s/ $one / /g" | xargs`
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# "lib1 lib2 lib3" -> "-llib1 -llib2 -llib3"
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l_list=`echo " $without_one " | sed -e 's: \([^- ][^ ]*\): -l\1:g'`
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test x"$l_list" != x"" && l_list="$START_GROUP $l_list $END_GROUP"
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$debug && echo "Trying -l options: '$l_list'"
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try $CC $CFLAGS $LDFLAGS \
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-o $EXE \
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$SORT_COMMON \
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$SORT_SECTION \
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$GC_SECTIONS \
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$START_GROUP $O_FILES $A_FILES $END_GROUP \
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$l_list
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if test $? = 0; then
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echo " Library $one is not needed, excluding it"
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LDLIBS="$without_one"
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all_needed=false
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last_needed=false
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else
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echo " Library $one is needed, can't exclude it (yet)"
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last_needed=true
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fi
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done
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# All libs were needed, can't remove any
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$all_needed && break
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# Optimization: was the last tried lib needed?
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if $last_needed; then
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# Was it the only one lib left? Don't test again then.
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{ echo "$LDLIBS" | grep -q ' '; } || break
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fi
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done
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# Make the binary with final, minimal list of libs
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echo "Final link with: ${LDLIBS:-<none>}"
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l_list=`echo " $LDLIBS " | sed -e 's: \([^- ][^ ]*\): -l\1:g'`
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test "x$l_list" != "x" && l_list="$START_GROUP $l_list $END_GROUP"
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# --verbose gives us gobs of info to stdout (e.g. linker script used)
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if ! test -f busybox_ldscript; then
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try $CC $CFLAGS $LDFLAGS \
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-o $EXE \
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$SORT_COMMON \
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$SORT_SECTION \
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$GC_SECTIONS \
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$START_GROUP $O_FILES $A_FILES $END_GROUP \
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$l_list \
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$INFO_OPTS \
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|| {
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cat $EXE.out
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exit 1
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}
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else
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echo "Custom linker script 'busybox_ldscript' found, using it"
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# Add SORT_BY_ALIGNMENT to linker script (found in $EXE.out):
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# .rodata : { *(.rodata SORT_BY_ALIGNMENT(.rodata.*) .gnu.linkonce.r.*) }
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# *(.data SORT_BY_ALIGNMENT(.data.*) .gnu.linkonce.d.*)
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# *(.bss SORT_BY_ALIGNMENT(.bss.*) .gnu.linkonce.b.*)
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# This will eliminate most of the padding (~3kb).
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# Hmm, "ld --sort-section alignment" should do it too.
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try $CC $CFLAGS $LDFLAGS \
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-o $EXE \
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$SORT_COMMON \
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$SORT_SECTION \
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$GC_SECTIONS \
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-Wl,-T,busybox_ldscript \
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$START_GROUP $O_FILES $A_FILES $END_GROUP \
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$l_list \
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$INFO_OPTS \
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|| {
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cat $EXE.out
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exit 1
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}
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fi
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. ./.config
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sharedlib_dir="0_lib"
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if test "$CONFIG_BUILD_LIBBUSYBOX" = y; then
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mkdir "$sharedlib_dir" 2>/dev/null
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test -d "$sharedlib_dir" || {
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echo "Cannot make directory $sharedlib_dir"
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exit 1
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}
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ln -s "libbusybox.so.$BB_VER" "$sharedlib_dir"/libbusybox.so 2>/dev/null
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EXE="$sharedlib_dir/libbusybox.so.${BB_VER}_unstripped"
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try $CC $CFLAGS $LDFLAGS \
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-o $EXE \
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-shared -fPIC \
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-Wl,--enable-new-dtags \
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-Wl,-z,combreloc \
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-Wl,-soname="libbusybox.so.$BB_VER" \
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-Wl,--undefined=lbb_main \
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$SORT_COMMON \
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$SORT_SECTION \
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$START_GROUP $A_FILES $END_GROUP \
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$l_list \
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$INFO_OPTS \
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|| {
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echo "Linking $EXE failed"
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cat $EXE.out
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exit 1
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}
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$STRIP -s --remove-section=.note --remove-section=.comment $EXE -o "$sharedlib_dir/libbusybox.so.$BB_VER"
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chmod a+x "$sharedlib_dir/libbusybox.so.$BB_VER"
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echo "libbusybox: $sharedlib_dir/libbusybox.so.$BB_VER"
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fi
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if test "$CONFIG_FEATURE_SHARED_BUSYBOX" = y; then
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EXE="$sharedlib_dir/busybox_unstripped"
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try $CC $CFLAGS $LDFLAGS \
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-o $EXE \
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$SORT_COMMON \
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$SORT_SECTION \
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$GC_SECTIONS \
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$START_GROUP $O_FILES $END_GROUP \
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-L"$sharedlib_dir" -lbusybox \
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$l_list \
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$INFO_OPTS \
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|| {
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echo "Linking $EXE failed"
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cat $EXE.out
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exit 1
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}
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$STRIP -s --remove-section=.note --remove-section=.comment $EXE -o "$sharedlib_dir/busybox"
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echo "busybox linked against libbusybox: $sharedlib_dir/busybox"
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fi
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if test "$CONFIG_FEATURE_INDIVIDUAL" = y; then
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echo "Linking individual applets against libbusybox (see $sharedlib_dir/*)"
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gcc -DNAME_MAIN -E -include include/autoconf.h include/applets.h \
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| grep -v "^#" \
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| grep -v "^$" \
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> applet_lst.tmp
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while read name main junk; do
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echo "\
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void lbb_prepare(const char *applet, char **argv);
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int $main(int argc, char **argv);
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int main(int argc, char **argv)
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{
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lbb_prepare(\"$name\", argv);
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return $main(argc, argv);
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}
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" >"$sharedlib_dir/applet.c"
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EXE="$sharedlib_dir/$name"
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try $CC $CFLAGS $LDFLAGS "$sharedlib_dir/applet.c" \
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-o $EXE \
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$SORT_COMMON \
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$SORT_SECTION \
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$GC_SECTIONS \
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-L"$sharedlib_dir" -lbusybox \
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-Wl,--warn-common \
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|| {
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echo "Linking $EXE failed"
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cat $EXE.out
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exit 1
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}
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rm -- "$sharedlib_dir/applet.c" $EXE.out
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$STRIP -s --remove-section=.note --remove-section=.comment $EXE
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done <applet_lst.tmp
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fi
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# libbusybox.so is needed only for -lbusybox at link time,
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# it is not needed at runtime. Deleting to reduce confusion.
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rm "$sharedlib_dir"/libbusybox.so 2>/dev/null
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exit 0 # or else we may confuse make
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