Re: [Valgrind-users] valgrind with LD_PRELOAD

[Samuel Q. <Sam...@sy...>]

| Maybe you can do it with a shell-script wrapper? Eg:
|
| run-me.sh:
| #! /bin/sh
| LD_PRELOAD=./libfakec.so ./myapp -e
|
| Then run:
|
| valgrind --trace-children=yes ./run-me.sh

This has been my approach.  Now I am suspicious that  - -trace-children=yes is not working like I hoped.  I get the EXACT SAME output whether I have  - -trace–children=yes or do not have that option.  So I think there must be more to getting  - -trace-children=yes to behave like I want.

Here is the output.  Every number is the same whether or not I have "- -trace-children=yes".

==13527== HEAP SUMMARY:
==13527==     in use at exit: 19,116 bytes in 584 blocks
==13527==   total heap usage: 766 allocs, 182 frees, 29,553 bytes allocated
==13527==
==13527== LEAK SUMMARY:
==13527==    definitely lost: 0 bytes in 0 blocks
==13527==    indirectly lost: 0 bytes in 0 blocks
==13527==      possibly lost: 0 bytes in 0 blocks
==13527==    still reachable: 19,116 bytes in 584 blocks
==13527==         suppressed: 0 bytes in 0 blocks



From: Mike Shal <ma...@gm...<mailto:ma...@gm...>>
Date: Tue, Jan 14 9:29 AM
To: Samuel Quiring <sam...@sy...<mailto:sam...@sy...>>
Cc: "val...@li...<mailto:val...@li...>" <val...@li...<mailto:val...@li...>>
Subject: Re: [Valgrind-users] valgrind with LD_PRELOAD

On Tue, Jan 14, 2014 at 10:14 AM, Samuel Quiring <Sam...@sy...<mailto:Sam...@sy...>> wrote:
Greetings,

I invoke my program as follows:

     LD_PRELOAD=./libfakec.so ./my_app –e

The LD_PRELOAD environment variable tells the loader that libfakec.so should be loaded BEFORE every other library including the C runtime, libc.so (see http://stackoverflow.com/questions/426230/what-is-the-ld-preload-trick, for example).  I am substituting some of my own routines for standard library calls.  My app is working like I want, but the question is how to run the app under valgrind?  I tried this:

    valgrind LD_PRELOAD=./libfakec.so ./my_app –e

But valgrind gave and error saying that "LD_PRELOAD=./libfakec.so ./my_app –e" is not a valid path.  In theory, I could put the LD_PRELOAD before the valgrind invocation:

    LD_PRELOAD=./libfakec.so  valgrind  ./my_app –e

But then valgrind would also be using my special library routines and I am pretty sure that will not work.


Maybe you can do it with a shell-script wrapper? Eg:

run-me.sh:
#! /bin/sh
LD_PRELOAD=./libfakec.so ./myapp -e

Then run:

valgrind --trace-children=yes ./run-me.sh

-Mike