Using lex in a shared library

[Xin LI]

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On 2010/07/02 16:34, Matthew Fleming wrote:
> On Fri, Jul 2, 2010 at 4:02 PM, Garrett Cooper <yanefbsd at gmail.com> wrote:
>> On Fri, Jul 2, 2010 at 2:51 PM, Matthew Fleming <mdf356 at gmail.com> wrote:
>>> I have the following Makefile for a shared library at $work:
>>>
>>> ISI_TOP=        ../..
>>>
>>> LIB=            isi_date
>>> SHLIB_MAJOR=    1
>>> SHLIB_MINOR=    0
>>> SRCS=           date.c date_parser.new.c lex.yy.c
>>> INCS=           date.h
>>> INCLUDEDIR=     /usr/include/isi_date
>>>
>>> YFLAGS+=        -vt
>>> FLEX=           /usr/bin/flex
>>> LDADD=          -ll
>>>
>>> CLEANFILES+=    date_parser.new.c y.tab.h y.tab.c lex.yy.c y.output \
>>>                check_date.log test
>>>
>>> lex.yy.c: date_lexer.new.l
>>>        ${FLEX} $>
>>>
>>> CFLAGS+=        -I${.CURDIR}
>>> #CFLAGS+=       -g
>>>
>>> .include "${ISI_TOP}/isi.lib.mk"
>>>
>>>
>>>
>>> This builds fine as on i386.  I'm trying to get all our user-space to
>>> be 64-bit clean, and I run into an error when building on amd64:
>>>
>>> /data/sb/BR_MDF_64CLEAN/obj/data/sb/BR_MDF_64CLEAN/src/tmp/usr/bin/ld:
>>> /data/sb/BR_MDF_64CLEAN/obj/data/sb/BR_MDF_64CLEAN/src/tmp/usr/lib/libl.a(libyywrap.o):
>>> relocation R_X86_64_32 can not be used when making a shared object;
>>> recompile with -fPIC
>>> /data/sb/BR_MDF_64CLEAN/obj/data/sb/BR_MDF_64CLEAN/src/tmp/usr/lib/libl.a:
>>> could not read symbols: Bad value
>>>
>>> The following diff makes the compile work, but I have no idea (yet)
>>> whether this will run, if it's the right solution, etc.
>>>
>>>
>>> Index: usr.bin/lex/lib/Makefile
>>> ===================================================================
>>> --- usr.bin/lex/lib/Makefile    (revision 153343)
>>> +++ usr.bin/lex/lib/Makefile    (working copy)
>>> @@ -4,11 +4,16 @@
>>>
>>>  LIB=    ln
>>>  SRCS=   libmain.c libyywrap.c
>>> -NO_PIC=
>>> +#NO_PIC=
>>>
>>> +SHLIB_MAJOR=   1
>>> +SHLIB_MINOR=   0
>>> +
>>>  .if ${MK_INSTALLLIB} != "no"
>>>  LINKS=  ${LIBDIR}/libln.a ${LIBDIR}/libl.a
>>>  LINKS+=        ${LIBDIR}/libln.a ${LIBDIR}/libfl.a
>>> +LINKS+=        ${LIBDIR}/libln.so ${LIBDIR}/libl.so
>>> +LINKS+=        ${LIBDIR}/libln${LIB_SUFFIX}.so ${LIBDIR}/libl${LIB_SUFFIX}.so
>>>  .endif
>>>
>>>  .if ${MK_PROFILE} != "no"
>>
>> The static-only version was done on purpose:
>>
>> Revision 1.2: download - view: text, markup, annotated  - select for diffs
>> Thu Aug 25 23:11:07 1994 UTC (15 years, 10 months ago) by wollman
>> Branches: MAIN
>> CVS tags: RELENG_2_1_7_RELEASE, RELENG_2_1_6_RELEASE,
>> RELENG_2_1_6_1_RELEASE, RELENG_2_1_5_RELEASE, RELENG_2_1_0_RELEASE,
>> RELENG_2_1_0_BP, RELENG_2_0_5_RELEASE, RELENG_2_0_5_BP,
>> RELENG_2_0_5_ALPHA, RELENG_2_0_5, RELEASE_2_0, BETA_2_0, ALPHA_2_0
>> Branch point for: RELENG_2_1_0
>> Diff to: previous 1.1: preferred, colored
>> Changes since revision 1.1: +2 -8 lines
>>
>> We really, really /don't/ want to have a shared lex library.  Also,
>> current users should note that the old 1.1.5 lex can't process the
>> new scan.l, so you have to copy initscan.c to obj/scan.c before it will
>> build.
>>
>> Garrett Wollman probably has more information about why this was done.
>>
>> I think that fixing the lib to build with the appropriate options (not
>> -m32, or CPUTYPE => some 32-bit x86 variant, etc) is what really needs
>> to be done here.
> 
> I guess I'm still confused.  The isi_date library compiles fine if
> it's for i386, but switching to amd64 gives this error.  Since I
> didn't specify any -m32 flags or anything, and it's essentially using
> the standard bsd.lib.mk magic, I am trying to figure out why the
> 32-bit isi_date.1.so built and the 64-bit one won't.  Was the 32-bit
> version building successfully an unfortunate fluke?  What build flags
> would get the shared library to link with -ll?

I think that amd64 requires a static library be compiled with -fPIC if
it's being linked into shared object.  This should not be done for
normal static libraries, though, as this could give some performance
penalty when it's not needed (i.e. a static binary).

> Unfortunately, I didn't write this library, and I don't know anything
> about lex(1), so if I need my own yywrap() that might be fine, but I
> wouldn't have the first clue what to put in there. :-(

I think you could probably just change the code and use %option noyywrap
in the .l file?  (do your code call yywrap() directly?)

Cheers,
- -- 
Xin LI <delphij at delphij.net>	http://www.delphij.net/
FreeBSD - The Power to Serve!	       Live free or die
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