Re: [Valgrind-users] Wrapping function for strcpy

[Myoungkyu S. <mks...@gm...>]

Please see the followings. After posting my question at that moment, I
realized that I should specify the shared library name, because it's in
libc as you said. However, it didn't work using VG_Z_LIBC_SONAME.

Best regards,
Myoungkyu


====================================================================

mksong@mksong:testwrap$ valgrind --trace-redir=yes -v ./w_main
==5111== Memcheck, a memory error detector
==5111== Copyright (C) 2002-2013, and GNU GPL'd, by Julian Seward et al.
==5111== Using Valgrind-3.10.0 and LibVEX; rerun with -h for copyright info
==5111== Command: ./w_main
==5111==
--5111-- Valgrind options:
--5111--    --trace-redir=yes
--5111--    -v
--5111-- Contents of /proc/version:
--5111--   Linux version 3.13.0-35-generic (buildd@roseapple) (gcc version
4.8.2 (Ubuntu 4.8.2-19ubuntu1) ) #62-Ubuntu SMP Fri Aug 15 01:58:01 UTC 2014
--5111-- Arch and hwcaps: X86, LittleEndian, x86-mmxext-sse1-sse2
--5111-- Page sizes: currently 4096, max supported 4096
--5111-- Valgrind library directory: /usr/local/lib/valgrind
--5111-- <<
--5111--    ------ REDIR STATE after VG_(redir_initialise) ------
--5111--    TOPSPECS of soname (hardwired)
--5111--      ld-linux.so.2             strlen                         R->
(0000.0) 0x380696b2
--5111--      ld-linux.so.2             index                          R->
(0000.0) 0x3806968d
--5111--    ------ ACTIVE ------
--5111-- >>
--5111-- Reading syms from /lib/i386-linux-gnu/ld-2.19.so
--5111--    svma 0x0000000860, avma 0x0004000860
--5111--   Considering /lib/i386-linux-gnu/ld-2.19.so ..
--5111--   .. CRC mismatch (computed 19686c0d wanted 131a893d)
--5111--   Considering /usr/lib/debug/lib/i386-linux-gnu/ld-2.19.so ..
--5111--   .. CRC is valid
--5111-- <<
--5111--    ------ REDIR STATE after VG_(redir_notify_new_DebugInfo) ------
--5111--    TOPSPECS of soname ld-linux.so.2 filename /lib/i386-linux-gnu/
ld-2.19.so
--5111--    TOPSPECS of soname (hardwired)
--5111--      ld-linux.so.2             strlen                         R->
(0000.0) 0x380696b2
--5111--      ld-linux.so.2             index                          R->
(0000.0) 0x3806968d
--5111--    ------ ACTIVE ------
--5111--     0x04017ce0 (index               ) R-> (0000.0) 0x3806968d ???
--5111--     0x04017ed0 (strlen              ) R-> (0000.0) 0x380696b2 ???
--5111-- >>
--5111-- Reading syms from
/home/mksong/workspace/.../valgrind_ubuntu14.04/valgrind-3.10.0/testwrap/w_main
--5111--    svma 0x00080483a0, avma 0x00080483a0

valgrind: m_demangle/demangle.c:231 (vgPlain_maybe_Z_demangle): the
'impossible' happened.
valgrind: symbol with a 'VG_Z_' prefix: _vgw00000ZU_VG_Z_LIBC_SONAME_strcpy.
see pub_tool_redir.h for an explanation.

host stacktrace:
==5111==    at 0x3804E604: ??? (in
/usr/local/lib/valgrind/memcheck-x86-linux)

sched status:
  running_tid=0


Note: see also the FAQ in the source distribution.
It contains workarounds to several common problems.
In particular, if Valgrind aborted or crashed after
identifying problems in your program, there's a good chance
that fixing those problems will prevent Valgrind aborting or
crashing, especially if it happened in m_mallocfree.c.

If that doesn't help, please report this bug to: www.valgrind.org

In the bug report, send all the above text, the valgrind
version, and what OS and version you are using.  Thanks.

====================================================================

On Fri, Sep 26, 2014 at 11:22 AM, Julian Seward <js...@ac...> wrote:

> On 09/23/2014 03:31 AM, Myoungkyu Song wrote:
> > I have a question, which maybe was discussed.  I would like to implement
> a
> > wrapper function for standard API such as "strcpy".  However, I failed to
> > do.  When I tested a user-defined function like "hello(char *, char *)"
> > below, I successfully wrapped it, accessing to arguments and a return
> > value.
>
> The problem is here
>
> > char* I_WRAP_SONAME_FNNAME_ZU(NONE,strcpy) ( char *dest, const char *src
> )
>
> By using "(NONE,strcpy)" you are requesting to wrap the function strcpy in
> the main executable (that's what "NONE") means.  But strcpy lives in
> libc.so.  Really you need to use VG_Z_LIBC_SONAME (with a suitable
> definition for VG_Z_LIBC_SONAME) to make it work.  Unfortunately the
> definition of VG_Z_LIBC_SONAME is system-dependent.
>
> You should be able to find all the examples you need in
> shared/vg_replace_strmem.c
>
> Note also, using -v is very helpful for debugging wrapping/intercept
> problems.  If you need complete details, also try --trace-redir=yes.
>
> J
>
>
>
>