[Bug ld/16936] New: $ORIGIN in shared library's rpath not used to find library dependencies at link time

[sdvormwa at mtu dot edu]

https://sourceware.org/bugzilla/show_bug.cgi?id=16936

            Bug ID: 16936
           Summary: $ORIGIN in shared library's rpath not used to find
                    library dependencies at link time
           Product: binutils
           Version: 2.23
            Status: NEW
          Severity: normal
          Priority: P2
         Component: ld
          Assignee: unassigned at sourceware dot org
          Reporter: sdvormwa at mtu dot edu

On Linux x86_64, it looks like ld does not respect $ORIGIN when used in a
library's DT_RPATH entry, unlike the runtime loader.  This leads to link errors
due to undefined symbols, which the runtime loader can actually find. 
Additionally, adding directories to the linker's search path with -L does not
suffice to find these dependent libraries, --rpath-link must be used.  A short
example is below:

$ cat lib/libbar.c
int bar( void )
{
    return 0;
}
$ cat lib/libfoo.c
extern int bar( void );

int foo( void )
{
    return bar();
}
$ cat main.c
extern int foo();

int main()
{
    return foo();
}
$ readelf -d lib/libfoo_fullpath.so

Dynamic section at offset 0x798 contains 23 entries:
  Tag        Type                         Name/Value
 0x0000000000000001 (NEEDED)             Shared library: [libbar.so]
 0x0000000000000001 (NEEDED)             Shared library: [libc.so.6]
 0x000000000000000e (SONAME)             Library soname: [libfoo_fullpath.so]
 0x000000000000000f (RPATH)              Library rpath:
[/ptmp/sdvormwa/ld_bug/lib]
 0x000000000000000c (INIT)               0x4c8
 0x000000000000000d (FINI)               0x6a8
 0x0000000000000004 (HASH)               0x158
 0x0000000000000005 (STRTAB)             0x2f8
 0x0000000000000006 (SYMTAB)             0x1a8
 0x000000000000000a (STRSZ)              212 (bytes)
 0x000000000000000b (SYMENT)             24 (bytes)
 0x0000000000000003 (PLTGOT)             0x200970
 0x0000000000000002 (PLTRELSZ)           48 (bytes)
 0x0000000000000014 (PLTREL)             RELA
 0x0000000000000017 (JMPREL)             0x498
 0x0000000000000007 (RELA)               0x408
 0x0000000000000008 (RELASZ)             144 (bytes)
 0x0000000000000009 (RELAENT)            24 (bytes)
 0x000000006ffffffe (VERNEED)            0x3e8
 0x000000006fffffff (VERNEEDNUM)         1
 0x000000006ffffff0 (VERSYM)             0x3cc
 0x000000006ffffff9 (RELACOUNT)          1
 0x0000000000000000 (NULL)               0x0
$ readelf -d lib/libfoo_origin.so

Dynamic section at offset 0x798 contains 23 entries:
  Tag        Type                         Name/Value
 0x0000000000000001 (NEEDED)             Shared library: [libbar.so]
 0x0000000000000001 (NEEDED)             Shared library: [libc.so.6]
 0x000000000000000e (SONAME)             Library soname: [libfoo.so]
 0x000000000000000f (RPATH)              Library rpath: [$ORIGIN]
 0x000000000000000c (INIT)               0x4c8
 0x000000000000000d (FINI)               0x6a8
 0x0000000000000004 (HASH)               0x158
 0x0000000000000005 (STRTAB)             0x2f8
 0x0000000000000006 (SYMTAB)             0x1a8
 0x000000000000000a (STRSZ)              208 (bytes)
 0x000000000000000b (SYMENT)             24 (bytes)
 0x0000000000000003 (PLTGOT)             0x200970
 0x0000000000000002 (PLTRELSZ)           48 (bytes)
 0x0000000000000014 (PLTREL)             RELA
 0x0000000000000017 (JMPREL)             0x498
 0x0000000000000007 (RELA)               0x408
 0x0000000000000008 (RELASZ)             144 (bytes)
 0x0000000000000009 (RELAENT)            24 (bytes)
 0x000000006ffffffe (VERNEED)            0x3e8
 0x000000006fffffff (VERNEEDNUM)         1
 0x000000006ffffff0 (VERSYM)             0x3c8
 0x000000006ffffff9 (RELACOUNT)          1
 0x0000000000000000 (NULL)               0x0
$ ldd lib/libfoo_fullpath.so
        linux-vdso.so.1 =>  (0x00007ffff81cb000)
        libbar.so => /ptmp/sdvormwa/ld_bug/lib/libbar.so (0x00007fc04c466000)
        libc.so.6 => /lib64/libc.so.6 (0x00007fc04c08c000)
        /lib64/ld-linux-x86-64.so.2 (0x00007fc04c86a000)
$ ldd lib/libfoo_origin.so
        linux-vdso.so.1 =>  (0x00007fff0e3ff000)
        libbar.so => /ptmp/sdvormwa/ld_bug/lib/libbar.so (0x00007f027c5de000)
        libc.so.6 => /lib64/libc.so.6 (0x00007f027c203000)
        /lib64/ld-linux-x86-64.so.2 (0x00007f027c9e1000)
$ gcc main.c -Llib/ -lfoo_fullpath && echo PASS
PASS
$ gcc main.c -Llib/ -lfoo_origin && echo PASS
${CUSTOM_LD_PATH}/x86_64-unknown-linux-gnu/bin/ld: warning: libbar.so, needed
by lib//libfoo.so, not found (try using -rpath or -rpath-link)
lib//libfoo.so: undefined reference to `bar'
collect2: ld returned 1 exit status
$ gcc main.c -Llib/ -lfoo_origin -Wl,--rpath-link=lib/ && echo PASS
PASS
$ ${CUSTOM_LD_PATH}/x86_64-unknown-linux-gnu/bin/ld --version
GNU ld (GNU Binutils) 2.23.1
Copyright 2012 Free Software Foundation, Inc.
This program is free software; you may redistribute it under the terms of
the GNU General Public License version 3 or (at your option) a later version.
This program has absolutely no warranty.

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