overriding system calls

[J . Robert von Behren]

Greetings!

I'm working on a user-level threads package, and would like to override system 
calls for read(), write(), etc. for existing apps.  I've checked mailing list 
archives, the glibc source, and tried out a number of options for both linking 
and loading the executables, but can't get things to work in all the 
environments I've tried.  (It seems to work on machines w/ older versions of 
glibc, but not newer versions.)  I'm hoping someone wiser than me can point me 
in the right direction to find a solution.  ;-)

Here's what I've done:

   * in my source, define my own read(), write(), etc.
   * alias __read() to my read(), etc. with the strong_alias() macro copied 
from the glibc source
   * run my test app w/ LD_PRELOAD=./my_lib.so testprog

This works with the following setup:

    glibc 2.2.5                   (debian libc6 2.2.5-11.2)
    ld-linux.so.2 -> ld-2.2.5.so  (debian libc6 2.2.5-11.2
    ld 2.12.90.0.1                (debian binutils 2.12.90.0.1-4)

This setup does _not_ work:

    glibc 2.3.1                   (debian libc6 2.3.1-13)
    ld-linux.so.2 -> ld-2.3.1.so  (debian libc6 2.3.1-13)
    ld 2.12.90.0.1                (debian binutils 2.12.90.0.1-4)

Is there something different I need to do for this to work with newer versions 
of glibc?  This feels to me like a FAQ or otherwise dumb question, but I'm at a 
loss as to where to look next.  If someone could point me in the right 
direction, I'd be much obliged!  ;-)

Best regards,

-Rob von Behren

P.S.  Please send replies directly to me as well as to the list, as I'm not a 
subscriber.




Unfortunately, I need to use the newer versions