uClibc, libstdc++, and readdir()

[Peter S. Mazinger]

On 26 May 2006, Jeff Warren wrote:

> On Thu, 2006-05-25 at 20:07, Mike Frysinger wrote:
> 
> > the uClibc ldd app isnt perfect ... sometimes it's better if you just use 
> > `readelf -d` and look at the DT_NEEDED entries
> > -mike
> 
>  arm-linux-readelf -d flyermarker (one of my C++ programs...)
>  
> Dynamic segment at offset 0x31fb4 contains 22 entries:
>   Tag        Type                         Name/Value
>  0x00000001 (NEEDED)                     Shared library:
> [libstdc++.so.5]
>  0x00000001 (NEEDED)                     Shared library: [libfloat.so.1]
>  0x00000001 (NEEDED)                     Shared library: [libgcc_s.so.1]

it seems you have linked against libc.a instead of libc.so

>  0x0000000c (INIT)                       0x98c4
>  0x0000000d (FINI)                       0x350c0
>  0x00000004 (HASH)                       0x8130
>  0x00000005 (STRTAB)                     0x8ec0
>  0x00000006 (SYMTAB)                     0x8590
>  0x0000000a (STRSZ)                      1622 (bytes)
>  0x0000000b (SYMENT)                     16 (bytes)
>  0x00000015 (DEBUG)                      0x0
>  0x00000003 (PLTGOT)                     0x42128
>  0x00000002 (PLTRELSZ)                   344 (bytes)
>  0x00000014 (PLTREL)                     REL
>  0x00000017 (JMPREL)                     0x976c
>  0x00000011 (REL)                        0x969c
>  0x00000012 (RELSZ)                      208 (bytes)
>  0x00000013 (RELENT)                     8 (bytes)
>  0x6ffffffe (VERNEED)                    0x963c
>  0x6fffffff (VERNEEDNUM)                 2
>  0x6ffffff0 (VERSYM)                     0x9516
>  0x00000000 (NULL)                       0x0
> 
>  arm-linux-readelf -d bin/busybox (this is version 1.1.2, which works
> fine).
>  
> Dynamic segment at offset 0x6d960 contains 17 entries:
>   Tag        Type                         Name/Value
>  0x00000001 (NEEDED)                     Shared library: [libfloat.so.1]
>  0x0000000c (INIT)                       0x902c
>  0x0000000d (FINI)                       0x63490
>  0x00000004 (HASH)                       0x8130
>  0x00000005 (STRTAB)                     0x8960
>  0x00000006 (SYMTAB)                     0x83b0
>  0x0000000a (STRSZ)                      1091 (bytes)
>  0x0000000b (SYMENT)                     16 (bytes)
>  0x00000015 (DEBUG)                      0x0
>  0x00000003 (PLTGOT)                     0x7da24
>  0x00000002 (PLTRELSZ)                   168 (bytes)
>  0x00000014 (PLTREL)                     REL
>  0x00000017 (JMPREL)                     0x8f84
>  0x00000011 (REL)                        0x8da4
>  0x00000012 (RELSZ)                      480 (bytes)
>  0x00000013 (RELENT)                     8 (bytes)
>  0x00000000 (NULL)                       0x0
> 
> 
> Actually it looks like ldd is fine as readelf -d reports the same thing.
> 	And I don't understand it but I could remove the libuClibc.so from the
> rootfs and bootup, like I said it would eventually hang, but that is the
> ONLY C library on my system, libc.so and all others are links pointing
> to uClibc.  Even BusyBox would run.  Eventually the system will hang,
> but I would expect something more catastrophic and immediate.  I don't
> understand it as using readdir() is obviously using the CLibrary, but it
> would still work.  
> 
> 	Now if I removed the libstdc++ library the effect on the program was
> immediate and they would not run.
> 
> 	The end result is good for me now and everything is working.  I just
> wanted to understand more what was going on as I would expect the
> program to link to uClibc and it does not, so as far as that goes, I
> still don't get it.
> 
> Regards,
> 
> Jeff Warren
> 
> 
> 

-- 
Peter S. Mazinger <ps dot m at gmx dot net>           ID: 0xA5F059F2
Key fingerprint = 92A4 31E1 56BC 3D5A 2D08  BB6E C389 975E A5F0 59F2