The errors occurred because I included libreplacemalloc in my tool,
which calls VG_USERREQ__GET_MALLOCFUNCS (getting a table full of NULL
function values), and then tries to call those functions instead of
malloc(). In hindsight, the "memory exhausted" error was a clue
pointing to this.
Removing the dependencies on LIBREPLACEMALLOC in Makefile.am solved the problem.
All the best,
Serguei Makarov
On Mon, Jun 26, 2017 at 5:41 PM, Serhei Makarov <serhei.pub...@gmail.com> wrote:
> Hello all,
>
> I'm writing a Valgrind tool that makes use of function wrapping. From
> what I understand, wrappers need to run on the simulated CPU. I wrote
> a simple example which imitates the way Memcheck uses
> mc_replace_strmem.c to generate a preloaded .so that contains my own
> wrappers. A simplified version of my code is attached; I've been
> having some problems with it.
>
> After compiling and running the tool (using the 3.12.0 codebase on
> Linux), the instrumented programs crash in odd ways:
>
> $ inst/bin/valgrind --tool=simplewrap ls
> ==1201== SimpleWrap, do only basic function wrapping
> ==1201== basic example for mailing list
> ==1201== Using Valgrind-3.12.0 and LibVEX; rerun with -h for copyright info
> ==1201== Command: ls
> ==1201==
> --1201-- VG_USERREQ__CLIENT_CALL1: func=0x0
> --1201-- VG_USERREQ__CLIENT_CALL1: func=0x0
> --1201-- VG_USERREQ__CLIENT_CALL1: func=0x0
> --1201-- VG_USERREQ__CLIENT_CALL1: func=0x0
> --1201-- VG_USERREQ__CLIENT_CALL1: func=0x0
> --1201-- VG_USERREQ__CLIENT_CALL1: func=0x0
> --1201-- VG_USERREQ__CLIENT_CALL1: func=0x0
> ls: memory exhausted
> ==1201==
>
> $ ./vg-in-place --tool=wrapsimple gcc --help
>
> ==1215== SimpleWrap, do only basic function wrapping
> ==1215== basic example for mailing list
> ==1215== Using Valgrind-3.12.0 and LibVEX; rerun with -h for copyright info
> ==1215== Command: gcc --help
> ==1215==
> --1215-- VG_USERREQ__CLIENT_CALL1: func=0x0
> --1215-- VG_USERREQ__CLIENT_CALL1: func=0x0
> terminate called without an active exception
> ==1215==
> ==1215== Process terminating with default action of signal 6 (SIGABRT)
> ==1215== at 0x516F91F: raise (raise.c:58)
> ==1215== by 0x5171519: abort (abort.c:89)
> ==1215== by 0x47347C: ??? (in /usr/bin/gcc)
> ==1215== by 0x472F05: ??? (in /usr/bin/gcc)
> ==1215== by 0x472F50: ??? (in /usr/bin/gcc)
> ==1215== by 0x471C51: ??? (in /usr/bin/gcc)
> ==1215== by 0x4717A7: ??? (in /usr/bin/gcc)
> ==1215== by 0x4657B6: ??? (in /usr/bin/gcc)
> ==1215== by 0x441FED: ??? (in /usr/bin/gcc)
> ==1215== by 0x481AAC: ??? (in /usr/bin/gcc)
> ==1215== by 0x515A38F: (below main) (libc-start.c:245)
> ==1215==
> Aborted (core dumped)
>
> These crashes also happen if I comment out the wrapper function and
> compile the tool with an 'empty' sw_wrap.c, so the cause appears to
> relate to something I'm (not) doing with the build system to set up
> the preloaded .so, rather than the way the wrapper itself is written.
> Does anyone have a suggestion for how to properly add function
> wrappers to a Valgrind tool?
>
> All the best,
> Serguei Makarov
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