Re: Weird ldd problem

[RVP <rvp%SDF.ORG@localhost>]

On Sun, 18 Jul 2021, Chavdar Ivanov wrote:

> # file ksh93
> ksh93: ELF 64-bit LSB executable, x86-64, version 1 (SYSV),
> dynamically linked, interpreter /usr/libexec/ld.elf_so, for NetBSD
> 9.99.45, with debug_info, not stripped
> # ldd ./ksh93
> ./ksh93:
>        -lm.0 => /usr/lib/libm.so.0
>        -lc.12 => /usr/lib/libc.so.12
>        -lexecinfo.0 => /usr/lib/libexecinfo.so.0
>        -lelf.2 => /usr/lib/libelf.so.2
>        -lgcc_s.1 => /usr/lib/libgcc_s.so.1
> # ldd ksh93
> ldd: bad execname `ksh93' in AUX vector: No such file or directory

That's coming from the run-time linker:

function expand() in src/libexec/ld.elf_so/expand.c when it tries
to expand $ORIGIN. You can create such a binary yourself like this:

---
$ cat foo.c
#include <stdio.h>

int
main(int argc, char* argv[])
{
        printf("%s\n", *argv);
        return 0;
}
$ cc -o foo foo.c -Wl,-rpath='$ORIGIN'
$ ldd ./foo
./foo:
        -lc.12 => /usr/lib/libc.so.12
$ ldd foo
ldd: bad execname `foo' in AUX vector: Undefined error: 0
$ readelf -d foo

Dynamic section at offset 0xbb8 contains 18 entries:
  Tag        Type                         Name/Value
 0x0000000000000001 (NEEDED)             Shared library: [libc.so.12]
 0x000000000000000f (RPATH)              Library rpath: [$ORIGIN]
 0x000000000000000c (INIT)               0x400530
 0x000000000000000d (FINI)               0x4009b0
 0x0000000000000004 (HASH)               0x400210
 0x0000000000000005 (STRTAB)             0x4003c8
 0x0000000000000006 (SYMTAB)             0x400260
 0x000000000000000a (STRSZ)              158 (bytes)
 0x000000000000000b (SYMENT)             24 (bytes)
 0x0000000000000015 (DEBUG)              0x0
 0x0000000000000003 (PLTGOT)             0x600d48
 0x0000000000000002 (PLTRELSZ)           120 (bytes)
 0x0000000000000014 (PLTREL)             RELA
 0x0000000000000017 (JMPREL)             0x4004b0
 0x0000000000000007 (RELA)               0x400468
 0x0000000000000008 (RELASZ)             72 (bytes)
 0x0000000000000009 (RELAENT)            24 (bytes)
 0x0000000000000000 (NULL)               0x0
---

Do a `readelf -d' on both ksh93s. You'll see the difference.

-RVP