Ruby's malloc wrapper found in gc.c .

gc.c

void *                                                                                                          
ruby_xmalloc(size)
    long size;
{
    void *mem;

    if (size < 0) {
    rb_raise(rb_eNoMemError, "negative allocation size (or too big)");
    }
    if (size == 0) size = 1;

    if (ruby_gc_stress || (malloc_increase+size) > malloc_limit) {
    garbage_collect();
    }
    RUBY_CRITICAL(mem = malloc(size));
    if (!mem) {
    garbage_collect();
    RUBY_CRITICAL(mem = malloc(size));
    if (!mem) {
        rb_memerror();
    }
    }
    malloc_increase += size;

    return mem;
}