release/src/router/busybox/scripts/trylink

   1 #!/bin/sh
   2
   3 debug=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
  39 try() {
  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 $?
  46 }
  47
  48 check_cc() {
  49     local tempname="$(mktemp)"
  50     local r
  51     echo "int main(int argc,char**argv){return argv?argc:0;}" >"$tempname".c
  52     # Can use "-o /dev/null", but older gcc tend to *unlink it* on failure! :(
  53     # Was using "-xc /dev/null", but we need a valid C program.
  54     # "eval" may be needed if CFLAGS can contain
  55     # '... -D"BB_VER=KBUILD_STR(1.N.M)" ...'
  56     # and we need shell to process quotes!
  57     $CC $CFLAGS $LDFLAGS $1 "$tempname".c -o "$tempname" >/dev/null 2>&1
  58     r=$?
  59     rm -f "$tempname" "$tempname".c "$tempname".o
  60     return $r
  61 }
  62
  63 check_libc_is_glibc() {
  64     local tempname="$(mktemp)"
  65     local r
  66     echo "\
  67         #include <stdlib.h>
  68         /* Apparently uclibc defines __GLIBC__ (compat trick?). Oh well. */
  69         #if defined(__GLIBC__) && !defined(__UCLIBC__)
  70         syntax error here
  71         #endif
  72         " >"$tempname".c
  73     ! $CC $CFLAGS "$tempname".c -c -o "$tempname".o >/dev/null 2>&1
  74     r=$?
  75     rm -f "$tempname" "$tempname".c "$tempname".o
  76     return $r
  77 }
  78
  79 EXE="$1"
  80 CC="$2"
  81 CFLAGS="$3"
  82 LDFLAGS="$4"
  83 O_FILES="$5"
  84 A_FILES="$6"
  85 LDLIBS="$7"
  86
  87 # The --sort-section option is not supported by older versions of ld
  88 SORT_SECTION="-Wl,--sort-section,alignment"
  89 if ! check_cc "-Wl,--sort-section,alignment"; then
  90     echo "Your linker does not support --sort-section,alignment"
  91     SORT_SECTION=""
  92 fi
  93
  94 START_GROUP="-Wl,--start-group"
  95 END_GROUP="-Wl,--end-group"
  96 INFO_OPTS="-Wl,--warn-common -Wl,-Map,$EXE.map -Wl,--verbose"
  97
  98 # gold may not support --sort-common (yet)
  99 SORT_COMMON="-Wl,--sort-common"
 100 if ! check_cc "-Wl,--sort-common"; then
 101     echo "Your linker does not support --sort-common"
 102     SORT_COMMON=""
 103 fi
 104
 105 # Static linking against glibc produces buggy executables
 106 # (glibc does not cope well with ld --gc-sections).
 107 # See sources.redhat.com/bugzilla/show_bug.cgi?id=3400
 108 # Note that glibc is unsuitable for static linking anyway.
 109 # We are removing -Wl,--gc-sections from link command line.
 110 GC_SECTIONS="-Wl,--gc-sections"
 111 if (. ./.config && test x"$CONFIG_STATIC" = x"y") then
 112     if check_libc_is_glibc; then
 113         echo "Static linking against glibc, can't use --gc-sections"
 114         GC_SECTIONS=""
 115     fi
 116 fi
 117 # The --gc-sections option is not supported by older versions of ld
 118 if test -n "$GC_SECTIONS"; then
 119     if ! check_cc "$GC_SECTIONS"; then
 120         echo "Your linker does not support $GC_SECTIONS"
 121         GC_SECTIONS=""
 122     fi
 123 fi
 124
 125 # Sanitize lib list (dups, extra spaces etc)
 126 LDLIBS=`echo "$LDLIBS" | xargs -n1 | sort | uniq | xargs`
 127
 128 # First link with all libs. If it fails, bail out
 129 echo "Trying libraries: $LDLIBS"
 130 # "lib1 lib2 lib3" -> "-llib1 -llib2 -llib3"
 131 l_list=`echo " $LDLIBS " | sed -e 's: \([^- ][^ ]*\): -l\1:g'`
 132 test "x$l_list" != "x" && l_list="$START_GROUP $l_list $END_GROUP"
 133 try $CC $CFLAGS $LDFLAGS \
 134         -o $EXE \
 135         $SORT_COMMON \
 136         $SORT_SECTION \
 137         $GC_SECTIONS \
 138         $START_GROUP $O_FILES $A_FILES $END_GROUP \
 139         $l_list \
 140 || {
 141     echo "Failed: $l_list"
 142     cat $EXE.out
 143     echo 'Note: if build needs additional libraries, put them in CONFIG_EXTRA_LDLIBS.'
 144     echo 'Example: CONFIG_EXTRA_LDLIBS="pthread dl tirpc audit pam"'
 145     exit 1
 146 }
 147
 148 # Now try to remove each lib and build without it.
 149 # Stop when no lib can be removed.
 150 while test "$LDLIBS"; do
 151     $debug && echo "Trying libraries: $LDLIBS"
 152     all_needed=true
 153     last_needed=false
 154     for one in $LDLIBS; do
 155         without_one=`echo " $LDLIBS " | sed "s/ $one / /g" | xargs`
 156         # "lib1 lib2 lib3" -> "-llib1 -llib2 -llib3"
 157         l_list=`echo " $without_one " | sed -e 's: \([^- ][^ ]*\): -l\1:g'`
 158         test x"$l_list" != x"" && l_list="$START_GROUP $l_list $END_GROUP"
 159         $debug && echo "Trying -l options: '$l_list'"
 160         try $CC $CFLAGS $LDFLAGS \
 161                 -o $EXE \
 162                 $SORT_COMMON \
 163                 $SORT_SECTION \
 164                 $GC_SECTIONS \
 165                 $START_GROUP $O_FILES $A_FILES $END_GROUP \
 166                 $l_list
 167         if test $? = 0; then
 168             echo " Library $one is not needed, excluding it"
 169             LDLIBS="$without_one"
 170             all_needed=false
 171             last_needed=false
 172         else
 173             echo " Library $one is needed, can't exclude it (yet)"
 174             last_needed=true
 175         fi
 176     done
 177     # All libs were needed, can't remove any
 178     $all_needed && break
 179     # Optimization: was the last tried lib needed?
 180     if $last_needed; then
 181         # Was it the only one lib left? Don't test again then.
 182         { echo "$LDLIBS" | grep -q ' '; } || break
 183     fi
 184 done
 185
 186 # Make the binary with final, minimal list of libs
 187 echo "Final link with: ${LDLIBS:-<none>}"
 188 l_list=`echo " $LDLIBS " | sed -e 's: \([^- ][^ ]*\): -l\1:g'`
 189 test "x$l_list" != "x" && l_list="$START_GROUP $l_list $END_GROUP"
 190 # --verbose gives us gobs of info to stdout (e.g. linker script used)
 191 if ! test -f busybox_ldscript; then
 192     try $CC $CFLAGS $LDFLAGS \
 193             -o $EXE \
 194             $SORT_COMMON \
 195             $SORT_SECTION \
 196             $GC_SECTIONS \
 197             $START_GROUP $O_FILES $A_FILES $END_GROUP \
 198             $l_list \
 199             $INFO_OPTS \
 200     || {
 201         cat $EXE.out
 202         exit 1
 203     }
 204 else
 205     echo "Custom linker script 'busybox_ldscript' found, using it"
 206     # Add SORT_BY_ALIGNMENT to linker script (found in $EXE.out):
 207     #  .rodata         : { *(.rodata SORT_BY_ALIGNMENT(.rodata.*) .gnu.linkonce.r.*) }
 208     #  *(.data SORT_BY_ALIGNMENT(.data.*) .gnu.linkonce.d.*)
 209     #  *(.bss SORT_BY_ALIGNMENT(.bss.*) .gnu.linkonce.b.*)
 210     # This will eliminate most of the padding (~3kb).
 211     # Hmm, "ld --sort-section alignment" should do it too.
 212     #
 213     # There is a ld hack which is meant to decrease disk usage
 214     # at the cost of more RAM usage (??!!) in standard ld script:
 215     #  /* Adjust the address for the data segment.  We want to adjust up to
 216     #     the same address within the page on the next page up.  */
 217     #  . = ALIGN (0x1000) - ((0x1000 - .) & (0x1000 - 1)); . = DATA_SEGMENT_ALIGN (0x1000, 0x1000);
 218     # Replace it with:
 219     #  . = ALIGN (0x1000); . = DATA_SEGMENT_ALIGN (0x1000, 0x1000);
 220     # to unconditionally align .data to the next page boundary,
 221     # instead of "next page, plus current offset in this page"
 222     try $CC $CFLAGS $LDFLAGS \
 223             -o $EXE \
 224             $SORT_COMMON \
 225             $SORT_SECTION \
 226             $GC_SECTIONS \
 227             -Wl,-T,busybox_ldscript \
 228             $START_GROUP $O_FILES $A_FILES $END_GROUP \
 229             $l_list \
 230             $INFO_OPTS \
 231     || {
 232         cat $EXE.out
 233         exit 1
 234     }
 235 fi
 236
 237 . ./.config
 238
 239 sharedlib_dir="0_lib"
 240
 241 if test "$CONFIG_BUILD_LIBBUSYBOX" = y; then
 242     mkdir "$sharedlib_dir" 2>/dev/null
 243     test -d "$sharedlib_dir" || {
 244         echo "Cannot make directory $sharedlib_dir"
 245         exit 1
 246     }
 247     ln -s "libbusybox.so.$BB_VER" "$sharedlib_dir"/libbusybox.so 2>/dev/null
 248
 249     EXE="$sharedlib_dir/libbusybox.so.${BB_VER}_unstripped"
 250     try $CC $CFLAGS $LDFLAGS \
 251             -o $EXE \
 252             -shared -fPIC \
 253             -Wl,--enable-new-dtags \
 254             -Wl,-z,combreloc \
 255             -Wl,-soname="libbusybox.so.$BB_VER" \
 256             -Wl,--undefined=lbb_main \
 257             $SORT_COMMON \
 258             $SORT_SECTION \
 259             $START_GROUP $A_FILES $END_GROUP \
 260             $l_list \
 261             $INFO_OPTS \
 262     || {
 263         echo "Linking $EXE failed"
 264         cat $EXE.out
 265         exit 1
 266     }
 267     $STRIP -s --remove-section=.note --remove-section=.comment $EXE -o "$sharedlib_dir/libbusybox.so.$BB_VER"
 268     chmod a+x "$sharedlib_dir/libbusybox.so.$BB_VER"
 269     echo "libbusybox: $sharedlib_dir/libbusybox.so.$BB_VER"
 270 fi
 271
 272 if test "$CONFIG_FEATURE_SHARED_BUSYBOX" = y; then
 273     EXE="$sharedlib_dir/busybox_unstripped"
 274     try $CC $CFLAGS $LDFLAGS \
 275             -o $EXE \
 276             $SORT_COMMON \
 277             $SORT_SECTION \
 278             $GC_SECTIONS \
 279             $START_GROUP $O_FILES $END_GROUP \
 280             -L"$sharedlib_dir" -lbusybox \
 281             $l_list \
 282             $INFO_OPTS \
 283     || {
 284         echo "Linking $EXE failed"
 285         cat $EXE.out
 286         exit 1
 287     }
 288     $STRIP -s --remove-section=.note --remove-section=.comment $EXE -o "$sharedlib_dir/busybox"
 289     echo "busybox linked against libbusybox: $sharedlib_dir/busybox"
 290 fi
 291
 292 if test "$CONFIG_FEATURE_INDIVIDUAL" = y; then
 293     echo "Linking individual applets against libbusybox (see $sharedlib_dir/*)"
 294     gcc -DNAME_MAIN -E -include include/autoconf.h include/applets.h \
 295     | grep -v "^#" \
 296     | grep -v "^ *$" \
 297     > applet_lst.tmp
 298     while read name main junk; do
 299
 300         echo "\
 301 void lbb_prepare(const char *applet, char **argv);
 302 int $main(int argc, char **argv);
 303
 304 int main(int argc, char **argv)
 305 {
 306         lbb_prepare(\"$name\", argv);
 307         return $main(argc, argv);
 308 }
 309 " >"$sharedlib_dir/applet.c"
 310
 311         EXE="$sharedlib_dir/$name"
 312         try $CC $CFLAGS $LDFLAGS "$sharedlib_dir/applet.c" \
 313                 -o $EXE \
 314                 $SORT_COMMON \
 315                 $SORT_SECTION \
 316                 $GC_SECTIONS \
 317                 -L"$sharedlib_dir" -lbusybox \
 318                 -Wl,--warn-common \
 319         || {
 320             echo "Linking $EXE failed"
 321             cat $EXE.out
 322             exit 1
 323         }
 324         rm -- "$sharedlib_dir/applet.c" $EXE.out
 325         $STRIP -s --remove-section=.note --remove-section=.comment $EXE
 326         # Let user see that we do something - list the names of created binaries:
 327         echo "$EXE"
 328
 329     done <applet_lst.tmp
 330 fi
 331
 332 # libbusybox.so is needed only for -lbusybox at link time,
 333 # it is not needed at runtime. Deleting to reduce confusion.
 334 rm "$sharedlib_dir"/libbusybox.so 2>/dev/null
 335 exit 0 # or else we may confuse make