sam@delftcc.UUCP (Sam Kendall) (11/19/85)
Index: usr.bin/lorder.sh 4.2BSD +FIX Description: Lorder(1) on (almost) all UNIX systems may produce incorrect ordering for object files containing uninitialized external (common) symbols. Lorder tries to classify all symbols as "defs" or "refs", but a common symbol can be either, depending on the other instances of the symbol in other object files. This is most important on V7 systems, where this bug can lead (and has led, at this site) to undefined symbol errors from the loader, due to incorrect archive ordering. This can also happen on 4.2BSD systems if ranlib(1) is not used. Lorder is less widely used on 4.2BSD and System 5.2 systems, but its use is necessary to ensure source portability to V7 and other systems (MS-DOS?) which lack System V's archive table of contents or 4.2BSD's ranlib. That's probably why it is still around. Note: this bug will not occur on System 5.0 and other systems whose loaders do not support common storage. Repeat-By: Write the following 3 files: main.c: main(){ f(); } extern.c: f(){ extern int common; common = 5; } common.c: int common; Compile them like this: cc -c main.c common.c extern.c ar cr lib.a `lorder common.o extern.o | tsort` cc main.o lib.a Ld will give a message about "_common" (or "common") undefined, because common.o was incorrectly placed before extern.o in the archive. Fix: Lorder is almost identical on all UNIX systems. The fix here is for the V7/4.2BSD version. For System V: (1) don't change the options to nm; (2) add to the sed script to make the added part parallel to the other 2 parts, rather than exactly like what I have below. The temporary files should be put in /tmp--otherwise lorder will fail if the current directory is not writable--but I haven't bothered. *** /usr/bin/lorder Tue Sep 27 12:54:25 1983 --- /usr/lbin/lorder Tue Aug 13 10:57:33 1985 *************** *** 1,4 trap "rm -f $$sym?ef; exit" 0 1 2 13 15 case $# in 0) echo usage: lorder file ... exit ;; --- 1,10 ----- trap "rm -f $$sym?ef; exit" 0 1 2 13 15 + + # modified 8/13/85 by sam@delftcc.UUCP. + # (1) 3rd tmp file $$symcef added for common blocks, which can sometimes + # be refs, sometimes defs. + # (2) -p option speeds up nm. + case $# in 0) echo usage: lorder file ... exit ;; *************** *** 6,12 *.o) set $1 $1 esac esac ! nm -g $* | sed ' /^$/d /:$/{ /\.o:/!d --- 12,18 ----- *.o) set $1 $1 esac esac ! nm -pg $* | sed ' /^$/d /:$/{ /\.o:/!d *************** *** 23,28 w '$$symdef' d } s/.* // G s/\n/ / --- 29,41 ----- w '$$symdef' d } + /C /{ + s/.* // + G + s/\n/ / + w '$$symcef' + d + } s/.* // G s/\n/ / *************** *** 30,34 d ' sort $$symdef -o $$symdef sort $$symref -o $$symref join $$symref $$symdef | sed 's/[^ ]* *//' --- 43,49 ----- d ' sort $$symdef -o $$symdef + sort $$symcef -o $$symcef sort $$symref -o $$symref { join $$symref $$symdef *************** *** 31,34 ' sort $$symdef -o $$symdef sort $$symref -o $$symref ! join $$symref $$symdef | sed 's/[^ ]* *//' --- 45,52 ----- sort $$symdef -o $$symdef sort $$symcef -o $$symcef sort $$symref -o $$symref ! { ! join $$symref $$symdef ! join $$symref $$symcef ! join $$symcef $$symdef ! } | sed 's/[^ ]* *//' ---- Sam Kendall Delft Consulting Corp. (212) 243-8700 {allegra, seismo!cmcl2, ihnp4}!delftcc!sam
henry@utzoo.UUCP (Henry Spencer) (11/24/85)
> ...This can also happen on 4.2BSD systems if ranlib(1) is not used. > Lorder is less widely used on 4.2BSD and System 5.2 systems, but > its use is necessary to ensure source portability to V7 and > other systems (MS-DOS?) which lack System V's archive table of > contents or 4.2BSD's ranlib.... Once again the Berkloids get credit for something they had nothing to do with... Ranlib came from Bell Labs and was included in V7, although it seems to have been a late addition and the as-distributed V7 libraries don't use it. -- Henry Spencer @ U of Toronto Zoology {allegra,ihnp4,linus,decvax}!utzoo!henry