How can I detect if a program is running from within valgrind?

Question

Is there a way to identify at run-time of an executable is being run from within valgrind? I have a set of C++ unit tests, and one of them expects std::vector::reserve to throw std::bad_alloc. When I run this under valgrind, it bails out completely, preventing me from testing for both memory leaks (using valgrind) and behavior (expecting the exception to be thrown).

Here's a minimal example that reproduces it:

#include <vector>
int main()
{
    size_t uint_max = static_cast<size_t>(-1);
    std::vector<char> v;
    v.reserve(uint_max);
}

Running valgrind, I get this output:

Warning: silly arg (-1) to __builtin_new()
new/new[] failed and should throw an exception, but Valgrind
   cannot throw exceptions and so is aborting instead.  Sorry.
   at 0x40192BC: VALGRIND_PRINTF_BACKTRACE (valgrind.h:319)
   by 0x401C823: operator new(unsigned) (vg_replace_malloc.c:164)
   by 0x80487BF: std::vector<char, std::allocator<char> >::reserve(unsigned) new_allocator.h:92)
   by 0x804874D: main (vg.cxx:6)

I'd like to modify my unit test to simply skip the offending code when it's being run from within valgrind. Is this possible?

Answer 1

You should look at this page from the Valgrind manual, it contains a RUNNING_ON_VALGRIND macro (included from valgrind.h) which does what you want.

Answer 2

If one does not want to include valgrind.h (which requires an autoconf test or similar) or use a wrapper, here's a heuristic for Linux (and other systems using ELF?): test the value of the LD_PRELOAD environment variable since Valgrind works by preloading libraries. I use the following test in C to check whether LD_PRELOAD contains the string "/valgrind/" or "/vgpreload":

int tests_run_within_valgrind (void)
{
  char *p = getenv ("LD_PRELOAD");
  if (p == NULL)
    return 0;
  return (strstr (p, "/valgrind/") != NULL ||
          strstr (p, "/vgpreload") != NULL);
}

Other systems might have a similar solution. I suggest the following command to see whether the environment mentions Valgrind:

valgrind env | grep -i valgrind

Edit: In the relatively unlikely event that you are trying to do this either on macOS or on FreeBSD i386 running on an amd64 kernel then the environment variables are different.

• macOS uses DYLD_INSERT_LIBRARIES
• FreeBSD uses LD_32_PRELOAD (ONLY for i386 on amd64, not amd64 on amd64 or i386 on i386).

Plain LD_PRELOAD should work for all Linux and Solaris variants.