uClibc, libstdc++, and readdir()

[Jeff Warren]

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]
 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