source: branches/3.2/mindi-busybox/scripts/trylink @ 3232

Last change on this file since 3232 was 3232, checked in by bruno, 5 years ago
  • Update mindi-busybox to 1.21.1
  • Property svn:executable set to *
File size: 8.8 KB
Line 
1#!/bin/sh
2
3debug=false
4
5# Linker flags used:
6#
7# Informational:
8# --warn-common
9# -Map $EXE.map
10# --verbose
11#
12# Optimizations:
13# --sort-common                 reduces padding
14# --sort-section alignment      reduces padding
15# --gc-sections                 throws out unused sections,
16#                               does not work for shared libs
17# -On                           Not used, maybe useful?
18#
19# List of files to link:
20# $l_list                       == --start-group -llib1 -llib2 --end-group
21# --start-group $O_FILES $A_FILES --end-group
22#
23# Shared library link:
24# -shared                       self-explanatory
25# -fPIC                         position-independent code
26# --enable-new-dtags            ?
27# -z,combreloc                  ?
28# -soname="libbusybox.so.$BB_VER"
29# --undefined=lbb_main          Seed name to start pulling from
30#                               (otherwise we'll need --whole-archive)
31# -static                       Not used, but may be useful! manpage:
32#                               "... This option can be used with -shared.
33#                               Doing so means that a shared library
34#                               is being created but that all of the library's
35#                               external references must be resolved by pulling
36#                               in entries from static libraries."
37
38
39try() {
40    printf "%s\n" "Output of:" >$EXE.out
41    printf "%s\n" "$*" >>$EXE.out
42    printf "%s\n" "==========" >>$EXE.out
43    $debug && echo "Trying: $*"
44    $@ >>$EXE.out 2>&1
45    return $?
46}
47
48check_cc() {
49    local tempname="/tmp/temp.$$.$RANDOM"
50    # Can use "-o /dev/null", but older gcc tend to *unlink it* on failure! :(
51    # "-xc": C language. "/dev/null" is an empty source file.
52    if $CC $1 -shared -xc /dev/null -o "$tempname".o >/dev/null 2>&1; then
53    echo "$1";
54    else
55    echo "$2";
56    fi
57    rm "$tempname".o 2>/dev/null
58}
59
60check_libc_is_glibc() {
61    local tempname="/tmp/temp.$$.$RANDOM"
62    echo "\
63    #include <stdlib.h>
64    /* Apparently uclibc defines __GLIBC__ (compat trick?). Oh well. */
65    #if defined(__GLIBC__) && !defined(__UCLIBC__)
66    syntax error here
67    #endif
68    " >"$tempname".c
69    if $CC "$tempname".c -c -o "$tempname".o >/dev/null 2>&1; then
70    echo "$2";
71    else
72    echo "$1";
73    fi
74    rm "$tempname".c "$tempname".o 2>/dev/null
75}
76
77EXE="$1"
78CC="$2"
79CFLAGS="$3"
80LDFLAGS="$4"
81O_FILES="$5"
82A_FILES="$6"
83LDLIBS="$7"
84
85# The --sort-section option is not supported by older versions of ld
86SORT_SECTION=`check_cc "-Wl,--sort-section,alignment" ""`
87
88START_GROUP="-Wl,--start-group"
89END_GROUP="-Wl,--end-group"
90INFO_OPTS="-Wl,--warn-common -Wl,-Map,$EXE.map -Wl,--verbose"
91
92# gold may not support --sort-common (yet)
93SORT_COMMON=`check_cc "-Wl,--sort-common" ""`
94
95# Static linking against glibc produces buggy executables
96# (glibc does not cope well with ld --gc-sections).
97# See sources.redhat.com/bugzilla/show_bug.cgi?id=3400
98# Note that glibc is unsuitable for static linking anyway.
99# We are removing -Wl,--gc-sections from link command line.
100GC_SECTIONS=`(
101. ./.config
102if test x"$CONFIG_STATIC" = x"y"; then
103    check_libc_is_glibc "" "-Wl,--gc-sections"
104else
105    echo "-Wl,--gc-sections"
106fi
107)`
108
109# The --gc-sections option is not supported by older versions of ld
110if test -n "$GC_SECTIONS"; then
111    GC_SECTIONS=`check_cc "$GC_SECTIONS" ""`
112fi
113
114# Sanitize lib list (dups, extra spaces etc)
115LDLIBS=`echo "$LDLIBS" | xargs -n1 | sort | uniq | xargs`
116
117# First link with all libs. If it fails, bail out
118echo "Trying libraries: $LDLIBS"
119# "lib1 lib2 lib3" -> "-llib1 -llib2 -llib3"
120l_list=`echo "$LDLIBS" | sed -e 's/ / -l/g' -e 's/^/-l/' -e 's/^-l$//'`
121test "x$l_list" != "x" && l_list="$START_GROUP $l_list $END_GROUP"
122try $CC $CFLAGS $LDFLAGS \
123    -o $EXE \
124    $SORT_COMMON \
125    $SORT_SECTION \
126    $GC_SECTIONS \
127    $START_GROUP $O_FILES $A_FILES $END_GROUP \
128    $l_list \
129|| {
130    echo "Failed: $l_list"
131    cat $EXE.out
132    exit 1
133}
134
135# Now try to remove each lib and build without it.
136# Stop when no lib can be removed.
137while test "$LDLIBS"; do
138    $debug && echo "Trying libraries: $LDLIBS"
139    all_needed=true
140    last_needed=false
141    for one in $LDLIBS; do
142    without_one=`echo " $LDLIBS " | sed "s/ $one / /g" | xargs`
143    # "lib1 lib2 lib3" -> "-llib1 -llib2 -llib3"
144    l_list=`echo "$without_one" | sed -e 's/ / -l/g' -e 's/^/-l/' -e 's/^-l$//'`
145    test x"$l_list" != x"" && l_list="$START_GROUP $l_list $END_GROUP"
146    $debug && echo "Trying -l options: '$l_list'"
147    try $CC $CFLAGS $LDFLAGS \
148        -o $EXE \
149        $SORT_COMMON \
150        $SORT_SECTION \
151        $GC_SECTIONS \
152        $START_GROUP $O_FILES $A_FILES $END_GROUP \
153        $l_list
154    if test $? = 0; then
155        echo " Library $one is not needed, excluding it"
156        LDLIBS="$without_one"
157        all_needed=false
158        last_needed=false
159    else
160        echo " Library $one is needed, can't exclude it (yet)"
161        last_needed=true
162    fi
163    done
164    # All libs were needed, can't remove any
165    $all_needed && break
166    # Optimization: was the last tried lib needed?
167    if $last_needed; then
168    # Was it the only one lib left? Don't test again then.
169    { echo "$LDLIBS" | grep -q ' '; } || break
170    fi
171done
172
173# Make the binary with final, minimal list of libs
174echo "Final link with: ${LDLIBS:-<none>}"
175l_list=`echo "$LDLIBS" | sed -e 's/ / -l/g' -e 's/^/-l/' -e 's/^-l$//'`
176test "x$l_list" != "x" && l_list="$START_GROUP $l_list $END_GROUP"
177# --verbose gives us gobs of info to stdout (e.g. linker script used)
178if ! test -f busybox_ldscript; then
179    try $CC $CFLAGS $LDFLAGS \
180        -o $EXE \
181        $SORT_COMMON \
182        $SORT_SECTION \
183        $GC_SECTIONS \
184        $START_GROUP $O_FILES $A_FILES $END_GROUP \
185        $l_list \
186        $INFO_OPTS \
187    || {
188    cat $EXE.out
189    exit 1
190    }
191else
192    echo "Custom linker script 'busybox_ldscript' found, using it"
193    # Add SORT_BY_ALIGNMENT to linker script (found in $EXE.out):
194    #  .rodata         : { *(.rodata SORT_BY_ALIGNMENT(.rodata.*) .gnu.linkonce.r.*) }
195    #  *(.data SORT_BY_ALIGNMENT(.data.*) .gnu.linkonce.d.*)
196    #  *(.bss SORT_BY_ALIGNMENT(.bss.*) .gnu.linkonce.b.*)
197    # This will eliminate most of the padding (~3kb).
198    # Hmm, "ld --sort-section alignment" should do it too.
199    try $CC $CFLAGS $LDFLAGS \
200        -o $EXE \
201        $SORT_COMMON \
202        $SORT_SECTION \
203        $GC_SECTIONS \
204        -Wl,-T,busybox_ldscript \
205        $START_GROUP $O_FILES $A_FILES $END_GROUP \
206        $l_list \
207        $INFO_OPTS \
208    || {
209    cat $EXE.out
210    exit 1
211    }
212fi
213
214. ./.config
215
216sharedlib_dir="0_lib"
217
218if test "$CONFIG_BUILD_LIBBUSYBOX" = y; then
219    mkdir "$sharedlib_dir" 2>/dev/null
220    test -d "$sharedlib_dir" || {
221    echo "Cannot make directory $sharedlib_dir"
222    exit 1
223    }
224    ln -s "libbusybox.so.$BB_VER" "$sharedlib_dir"/libbusybox.so 2>/dev/null
225
226    EXE="$sharedlib_dir/libbusybox.so.${BB_VER}_unstripped"
227    try $CC $CFLAGS $LDFLAGS \
228        -o $EXE \
229        -shared -fPIC \
230        -Wl,--enable-new-dtags \
231        -Wl,-z,combreloc \
232        -Wl,-soname="libbusybox.so.$BB_VER" \
233        -Wl,--undefined=lbb_main \
234        $SORT_COMMON \
235        $SORT_SECTION \
236        $START_GROUP $A_FILES $END_GROUP \
237        $l_list \
238        $INFO_OPTS \
239    || {
240    echo "Linking $EXE failed"
241    cat $EXE.out
242    exit 1
243    }
244    $STRIP -s --remove-section=.note --remove-section=.comment $EXE -o "$sharedlib_dir/libbusybox.so.$BB_VER"
245    chmod a+x "$sharedlib_dir/libbusybox.so.$BB_VER"
246    echo "libbusybox: $sharedlib_dir/libbusybox.so.$BB_VER"
247fi
248
249if test "$CONFIG_FEATURE_SHARED_BUSYBOX" = y; then
250    EXE="$sharedlib_dir/busybox_unstripped"
251    try $CC $CFLAGS $LDFLAGS \
252        -o $EXE \
253        $SORT_COMMON \
254        $SORT_SECTION \
255        $GC_SECTIONS \
256        $START_GROUP $O_FILES $END_GROUP \
257        -L"$sharedlib_dir" -lbusybox \
258        $l_list \
259        $INFO_OPTS \
260    || {
261    echo "Linking $EXE failed"
262    cat $EXE.out
263    exit 1
264    }
265    $STRIP -s --remove-section=.note --remove-section=.comment $EXE -o "$sharedlib_dir/busybox"
266    echo "busybox linked against libbusybox: $sharedlib_dir/busybox"
267fi
268
269if test "$CONFIG_FEATURE_INDIVIDUAL" = y; then
270    echo "Linking individual applets against libbusybox (see $sharedlib_dir/*)"
271    gcc -DNAME_MAIN_CNAME -E -include include/autoconf.h include/applets.h \
272    | grep -v "^#" \
273    | grep -v "^$" \
274    > applet_lst.tmp
275    while read name main junk; do
276
277    echo "\
278void lbb_prepare(const char *applet, char **argv);
279int $main(int argc, char **argv);
280
281int main(int argc, char **argv)
282{
283    lbb_prepare(\"$name\", argv);
284    return $main(argc, argv);
285}
286" >"$sharedlib_dir/applet.c"
287
288    EXE="$sharedlib_dir/$name"
289    try $CC $CFLAGS $LDFLAGS "$sharedlib_dir/applet.c" \
290        -o $EXE \
291        $SORT_COMMON \
292        $SORT_SECTION \
293        $GC_SECTIONS \
294        -L"$sharedlib_dir" -lbusybox \
295        -Wl,--warn-common \
296    || {
297        echo "Linking $EXE failed"
298        cat $EXE.out
299        exit 1
300    }
301    rm -- "$sharedlib_dir/applet.c" $EXE.out
302    $STRIP -s --remove-section=.note --remove-section=.comment $EXE
303
304    done <applet_lst.tmp
305fi
306
307# libbusybox.so is needed only for -lbusybox at link time,
308# it is not needed at runtime. Deleting to reduce confusion.
309rm "$sharedlib_dir"/libbusybox.so 2>/dev/null
310exit 0 # or else we may confuse make
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