[Bug 1923361] Re: unable to link xdr functions with groovy and hirsute

[Christian Ehrhardt ]

FYI this is a spin off from
https://bugs.launchpad.net/ubuntu/+source/glusterfs/+bug/1905360

It is also related to the same seen in libvirt:
https://listman.redhat.com/archives/libvir-list/2020-August/msg00921.html

I have resolved it in those and others.
The TL;DR is that Ubuntu has kept this in glibc for years (was default disabled, but we kept it for compatibility) and now finally upstream removed it which causes this bumpy ride.

Still within impish we have
ii  libc6:amd64     2.34-0ubuntu2 amd64        GNU C Library: Shared libraries
ii  libtirpc3:amd64 1.3.2-2       amd64        transport-independent RPC library

And the example symbol that Dominique referred (as well as others that I
hit in my other cases) are present in both but gladly properly versioned
differently:

root at i:~# eu-readelf -a /lib/x86_64-linux-gnu/libc.so.6 | grep xdr_void | grep GLOBAL
  191: 000000000016da90     10 FUNC    GLOBAL DEFAULT       16 xdr_void at GLIBC_2.2.5
root at i:~# eu-readelf -a /lib/x86_64-linux-gnu/libtirpc.so.3.0.0 | grep xdr_void | grep GLOBAL
  306: 0000000000013e70     10 FUNC    GLOBAL DEFAULT       15 xdr_void@@TIRPC_0.3.0


You can just look at the linking step by keeping interim files:
$ gcc -v -o testxdr -save-temps=obj -I/usr/include/tirpc -L /usr/lib/x86_64-linux-gnu -ltirpc testxdr.c

Then you can re-run just the linking step and inspect the .o
$ /usr/lib/gcc/x86_64-linux-gnu/11/collect2 -plugin /usr/lib/gcc/x86_64-linux-gnu/11/liblto_plugin.so -plugin-opt=/usr/lib/gcc/x86_64-linux-gnu/11/lto-wrapper -plugin-opt=-fresolution=testxdr.res -plugin-opt=-pass-through=-lgcc -plugin-opt=-pass-through=-lgcc_s -plugin-opt=-pass-through=-lc -plugin-opt=-pass-through=-lgcc -plugin-opt=-pass-through=-lgcc_s --build-id --eh-frame-hdr -m elf_x86_64 --hash-style=gnu --as-needed -dynamic-linker /lib64/ld-linux-x86-64.so.2 -pie -z now -z relro -o testxdr /usr/lib/gcc/x86_64-linux-gnu/11/../../../x86_64-linux-gnu/Scrt1.o /usr/lib/gcc/x86_64-linux-gnu/11/../../../x86_64-linux-gnu/crti.o /usr/lib/gcc/x86_64-linux-gnu/11/crtbeginS.o -L/usr/lib/x86_64-linux-gnu -L/usr/lib/gcc/x86_64-linux-gnu/11 -L/usr/lib/gcc/x86_64-linux-gnu/11/../../../x86_64-linux-gnu -L/usr/lib/gcc/x86_64-linux-gnu/11/../../../../lib -L/lib/x86_64-linux-gnu -L/lib/../lib -L/usr/lib/x86_64-linux-gnu -L/usr/lib/../lib -L/usr/lib/gcc/x86_64-linux-gnu/11/../../.. -ltirpc testxdr.o -lgcc --push-state --as-needed -lgcc_s --pop-state -lc -lgcc --push-state --as-needed -lgcc_s --pop-state /usr/lib/gcc/x86_64-linux-gnu/11/crtendS.o /usr/lib/gcc/x86_64-linux-gnu/11/../../../x86_64-linux-gnu/crtn.o

$ eu-readelf -a testxdr.o | grep xdr_void
  0x0000000000000009  X86_64_PLT32    000000000000000000      -4 xdr_void
    4: 0000000000000000      0 NOTYPE  GLOBAL DEFAULT    UNDEF xdr_void
  [    10]  xdr_void


I'd expect/want to see (maybe only after linking) something like:
  149: 0000000000000000      0 FUNC    GLOBAL DEFAULT    UNDEF xdr_uint64_t at TIRPC_0.3.0 (13)


I've checked the other successful builds that properly link against libtirpc now.
They all specify the target lib explicitly at build time.

In the short time I had I couldn't find where they pick it up, but this
makes your test-build work fine:

$ gcc -o testxdr -I/usr/include/tirpc -L /usr/lib/x86_64-linux-gnu
-ltirpc testxdr.c /usr/lib/x86_64-linux-gnu/libtirpc.so

^^ works
And now also we have the proper linkage from 0.3.0
$ eu-readelf -a testxdr | grep xdr_void
  0x0000000000003fd0  X86_64_JUMP_SLOT 000000000000000000      +0 xdr_void
    4: 0000000000000000      0 FUNC    GLOBAL DEFAULT    UNDEF xdr_void at TIRPC_0.3.0 (3)
   28: 0000000000000000      0 FUNC    GLOBAL DEFAULT    UNDEF xdr_void at TIRPC_0.3.0
  [   174]  xdr_void at TIRPC_0.3.0
  [    46]  xdr_void

** Changed in: libtirpc (Ubuntu)
       Status: New => Confirmed

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https://bugs.launchpad.net/bugs/1923361

Title:
  unable to link xdr functions with groovy and hirsute

Status in libtirpc package in Ubuntu:
  Confirmed

Bug description:
  Hi,
  I have a technical code that relies on XDR for it's internal data format. I cannot compile it anymore with hirsute (and groovy).

  As a simpler test I tried to compile

  #include <rpc/xdr.h>
  int main(){
  xdr_void();
  }

  called it testxdr.c 
  gcc -o testxdr -I/usr/include/tirpc -ltirpc testxdr.c

  -I and -l options are indicated by package-config.

  With the include compilation is OK but the linking fails with an indefinite reference to xdr_void.
  With focal, nor -I neither -l options are necessary, xdr functions are within glibc. 
  With hirsute nm says that xdr_void symbol is defined in libtirpc.so and surprisingly (for me) in glibc 2.33 (should have been removed since 2.32 ?)

  Any help is welcome !

  D.

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