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 $? 46} 47 48check_cc() { 49 tempname="$(mktemp tmp.XXXXXXXXXX)" 50 echo "int main(int argc,char**argv){return argv?argc:0;}" >"$tempname".c 51 # Can use "-o /dev/null", but older gcc tend to *unlink it* on failure! :( 52 # Was using "-xc /dev/null", but we need a valid C program. 53 # "eval" may be needed if CFLAGS can contain 54 # '... -D"BB_VER=KBUILD_STR(1.N.M)" ...' 55 # and we need shell to process quotes! 56 $CC $CFLAGS $LDFLAGS $1 "$tempname".c -o "$tempname" >/dev/null 2>&1 57 exitcode=$? 58 rm -f "$tempname" "$tempname".c "$tempname".o 59 return $exitcode 60} 61 62check_libc_is_glibc() { 63 tempname="$(mktemp tmp.XXXXXXXXXX)" 64 echo "\ 65 #include <stdlib.h> 66 /* Apparently uclibc defines __GLIBC__ (compat trick?). Oh well. */ 67 #if defined(__GLIBC__) && !defined(__UCLIBC__) 68 syntax error here 69 #endif 70 " >"$tempname".c 71 ! $CC $CFLAGS "$tempname".c -c -o "$tempname".o >/dev/null 2>&1 72 exitcode=$? 73 rm -f "$tempname" "$tempname".c "$tempname".o 74 return $exitcode 75} 76 77EXE="$1" 78CC="$2" 79CFLAGS="$3" 80LDFLAGS="$4" 81O_FILES="$5" 82A_FILES="$6" 83LDLIBS="$7" 84 85# The --sort-section option is not supported by older versions of ld 86SORT_SECTION="-Wl,--sort-section,alignment" 87if ! check_cc "-Wl,--sort-section,alignment"; then 88 echo "Your linker does not support --sort-section,alignment" 89 SORT_SECTION="" 90fi 91 92START_GROUP="-Wl,--start-group" 93END_GROUP="-Wl,--end-group" 94INFO_OPTS() { 95 echo "-Wl,--warn-common -Wl,-Map,$EXE.map -Wl,--verbose" 96} 97 98# gold may not support --sort-common (yet) 99SORT_COMMON="-Wl,--sort-common" 100if ! check_cc "-Wl,--sort-common"; then 101 echo "Your linker does not support --sort-common" 102 SORT_COMMON="" 103fi 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. 110GC_SECTIONS="-Wl,--gc-sections" 111if (. ./.config && test x"$CONFIG_STATIC" = x"y") then 112 if check_libc_is_glibc; then 113 echo "Static linking against glibc, can't use --gc-sections" 114 GC_SECTIONS="" 115 fi 116fi 117# The --gc-sections option is not supported by older versions of ld 118if test -n "$GC_SECTIONS"; then 119 if ! check_cc "$GC_SECTIONS"; then 120 echo "Your linker does not support $GC_SECTIONS" 121 GC_SECTIONS="" 122 fi 123fi 124 125# Sanitize lib list (dups, extra spaces etc) 126LDLIBS=`echo "$LDLIBS" | xargs -n1 | sort | uniq | xargs` 127 128# First link with all libs. If it fails, bail out 129echo "Trying libraries: $LDLIBS" 130# "lib1 lib2 lib3" -> "-llib1 -llib2 -llib3" 131l_list=`echo " $LDLIBS " | sed -e 's: \([^- ][^ ]*\): -l\1:g'` 132test "x$l_list" != "x" && l_list="$START_GROUP $l_list $END_GROUP" 133try $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 $EXE.out 143 echo 'Note: if build needs additional libraries, put them in CONFIG_EXTRA_LDLIBS.' 144 echo 'Example: CONFIG_EXTRA_LDLIBS="pthread dl tirpc audit pam"' 145 exit 1 146} 147 148# Now try to remove each lib and build without it. 149# Stop when no lib can be removed. 150while test "$LDLIBS"; do 151 $debug && echo "Trying libraries: $LDLIBS" 152 dropped_non_first_lib=false 153 first_lib=true 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 $first_lib || dropped_non_first_lib=true 171 else 172 echo " Library $one is needed, can't exclude it (yet)" 173 first_lib=false 174 fi 175 done 176 # We can stop trying to drop libs if either all libs were needed, 177 # or we excluded only the _first_ few. 178 # (else: we dropped some intermediate lib(s), maybe now we can succeed 179 # in dropping some of the preceding ones) 180 $dropped_non_first_lib || break 181done 182 183# Make the binary with final, minimal list of libs 184echo "Final link with: ${LDLIBS:-<none>}" 185l_list=`echo " $LDLIBS " | sed -e 's: \([^- ][^ ]*\): -l\1:g'` 186test "x$l_list" != "x" && l_list="$START_GROUP $l_list $END_GROUP" 187# --verbose gives us gobs of info to stdout (e.g. linker script used) 188if ! test -f busybox_ldscript; then 189 try $CC $CFLAGS $LDFLAGS \ 190 -o $EXE \ 191 $SORT_COMMON \ 192 $SORT_SECTION \ 193 $GC_SECTIONS \ 194 $START_GROUP $O_FILES $A_FILES $END_GROUP \ 195 $l_list \ 196 `INFO_OPTS` \ 197 || { 198 cat $EXE.out 199 exit 1 200 } 201else 202 echo "Custom linker script 'busybox_ldscript' found, using it" 203 # Add SORT_BY_ALIGNMENT to linker script (found in $EXE.out): 204 # .rodata : { *(.rodata SORT_BY_ALIGNMENT(.rodata.*) .gnu.linkonce.r.*) } 205 # *(.data SORT_BY_ALIGNMENT(.data.*) .gnu.linkonce.d.*) 206 # *(.bss SORT_BY_ALIGNMENT(.bss.*) .gnu.linkonce.b.*) 207 # This will eliminate most of the padding (~3kb). 208 # Hmm, "ld --sort-section alignment" should do it too. 209 # 210 # There is a ld hack which is meant to decrease disk usage 211 # at the cost of more RAM usage (??!!) in standard ld script: 212 # /* Adjust the address for the data segment. We want to adjust up to 213 # the same address within the page on the next page up. */ 214 # . = ALIGN (0x1000) - ((0x1000 - .) & (0x1000 - 1)); . = DATA_SEGMENT_ALIGN (0x1000, 0x1000); 215 # Replace it with: 216 # . = ALIGN (0x1000); . = DATA_SEGMENT_ALIGN (0x1000, 0x1000); 217 # to unconditionally align .data to the next page boundary, 218 # instead of "next page, plus current offset in this page" 219 try $CC $CFLAGS $LDFLAGS \ 220 -o $EXE \ 221 $SORT_COMMON \ 222 $SORT_SECTION \ 223 $GC_SECTIONS \ 224 -Wl,-T,busybox_ldscript \ 225 $START_GROUP $O_FILES $A_FILES $END_GROUP \ 226 $l_list \ 227 `INFO_OPTS` \ 228 || { 229 cat $EXE.out 230 exit 1 231 } 232fi 233 234. ./.config 235 236sharedlib_dir="0_lib" 237 238if test "$CONFIG_BUILD_LIBBUSYBOX" = y; then 239 mkdir "$sharedlib_dir" 2>/dev/null 240 test -d "$sharedlib_dir" || { 241 echo "Cannot make directory $sharedlib_dir" 242 exit 1 243 } 244 ln -s "libbusybox.so.$BB_VER" "$sharedlib_dir"/libbusybox.so 2>/dev/null 245 246 # Yes, "ld -shared -static" is a thing. It's a shared library which is itself static. 247 LBB_STATIC="" 248 test "$CONFIG_FEATURE_LIBBUSYBOX_STATIC" = y && LBB_STATIC="-Wl,-static" 249 250 EXE="$sharedlib_dir/libbusybox.so.${BB_VER}_unstripped" 251 try $CC $CFLAGS $LDFLAGS \ 252 -o $EXE \ 253 -shared -fPIC $LBB_STATIC \ 254 -Wl,--enable-new-dtags \ 255 -Wl,-z,combreloc \ 256 -Wl,-soname="libbusybox.so.$BB_VER" \ 257 -Wl,--undefined=lbb_main \ 258 $SORT_COMMON \ 259 $SORT_SECTION \ 260 $START_GROUP $A_FILES $END_GROUP \ 261 $l_list \ 262 `INFO_OPTS` \ 263 || { 264 echo "Linking $EXE failed" 265 cat $EXE.out 266 exit 1 267 } 268 $STRIP -s --remove-section=.note --remove-section=.comment $EXE -o "$sharedlib_dir/libbusybox.so.$BB_VER" 269 chmod a+x "$sharedlib_dir/libbusybox.so.$BB_VER" 270 echo "libbusybox: $sharedlib_dir/libbusybox.so.$BB_VER" 271fi 272 273if test "$CONFIG_FEATURE_SHARED_BUSYBOX" = y; then 274 EXE="$sharedlib_dir/busybox_unstripped" 275 try $CC $CFLAGS $LDFLAGS \ 276 -o $EXE \ 277 $SORT_COMMON \ 278 $SORT_SECTION \ 279 $GC_SECTIONS \ 280 $START_GROUP $O_FILES $END_GROUP \ 281 -L"$sharedlib_dir" -lbusybox \ 282 $l_list \ 283 `INFO_OPTS` \ 284 || { 285 echo "Linking $EXE failed" 286 cat $EXE.out 287 exit 1 288 } 289 $STRIP -s --remove-section=.note --remove-section=.comment $EXE -o "$sharedlib_dir/busybox" 290 echo "busybox linked against libbusybox: $sharedlib_dir/busybox" 291fi 292 293if test "$CONFIG_FEATURE_INDIVIDUAL" = y; then 294 echo "Linking individual applets against libbusybox (see $sharedlib_dir/*)" 295 gcc -DNAME_MAIN -E -include include/autoconf.h include/applets.h \ 296 | grep -v "^#" \ 297 | grep -v "^ *$" \ 298 > applet_lst.tmp 299 while read name main junk; do 300 301 echo "\ 302void lbb_prepare(const char *applet, char **argv); 303int $main(int argc, char **argv); 304 305int main(int argc, char **argv) 306{ 307 lbb_prepare(\"$name\", argv); 308 return $main(argc, argv); 309} 310" >"$sharedlib_dir/applet.c" 311 312 EXE="$sharedlib_dir/$name" 313 try $CC $CFLAGS $LDFLAGS "$sharedlib_dir/applet.c" \ 314 -o $EXE \ 315 $SORT_COMMON \ 316 $SORT_SECTION \ 317 $GC_SECTIONS \ 318 -L"$sharedlib_dir" -lbusybox \ 319 -Wl,--warn-common \ 320 || { 321 echo "Linking $EXE failed" 322 cat $EXE.out 323 exit 1 324 } 325 rm -- "$sharedlib_dir/applet.c" $EXE.out 326 $STRIP -s --remove-section=.note --remove-section=.comment $EXE 327 # Let user see that we do something - list the names of created binaries: 328 echo "$EXE" 329 330 done <applet_lst.tmp 331fi 332 333# libbusybox.so is needed only for -lbusybox at link time, 334# it is not needed at runtime. Deleting to reduce confusion. 335rm "$sharedlib_dir"/libbusybox.so 2>/dev/null 336exit 0 # or else we may confuse make 337