18.limits.traps.cpp

Go to the documentation of this file.

 
#include <limits>
 
#include <csignal>    // for SIGFPE, signal
 
#include <rw_any.h>      // for rw_any_t
#include <rw_cmdopt.h>   // for rw_enabled()
#include <rw_driver.h>   // for rw_test(), ...
 
 
#ifdef _RWSTD_OS_LINUX
 
   // use siglongjmp() and sigsetjmp() on Linux to avoid
   // http://sourceware.org/bugzilla/show_bug.cgi?id=2351
#  include <setjmp.h>    // for siglongjmp, sigsetjmp
 
jmp_buf jmp_env;
 
extern "C" {
 
void handle_fpe (int)
{
    siglongjmp (jmp_env, 1);
}
 
}   // extern "C"
 
#  define RW_SIGSETJMP(env, signo)   sigsetjmp (env, signo)
#else   // if !defined (_RWSTD_OS_LINUX)
 
#  include <csetjmp>    // for longjmp, setjmp
 
std::jmp_buf jmp_env;
 
extern "C" {
 
void handle_fpe (int)
{
    std::longjmp (jmp_env, 1);
}
 
}   // extern "C"
#  define RW_SIGSETJMP(env, ignore)   setjmp (env)
#endif   // _RWSTD_OS_LINUX
 
 
 
#ifdef _MSC_VER
   // silence useless MSVC warnings:
   // 4800: 'int' : forcing value to bool 'true' or 'false'
   // 4804: '/' : unsafe use of type 'bool' in operation
#  pragma warning (disable: 4800 4804)
 
   // use Structured Exception Handling to detect arithmetic exceptions
#  define TRY           __try
#  define EXCEPT(arg)   __except (arg)
#else
#  define TRY              if (1)
#  define EXCEPT(ignore)   else if (0)
#endif   // _MSC_VER
 
 
template <class numT>
inline void
try_trap (const volatile numT &one, const volatile numT &zero,
           numT &result, bool &trapped)
{
    TRY {
        result = one / zero;
    }
    EXCEPT (1) {
        // Windows SEH hackery
        trapped = true;
    }
}
 
 
template <class numT>
numT test_traps (numT, int lineno, bool)
{
    static const char* const tname = rw_any_t (numT ()).type_name ();
 
    if (!rw_enabled (tname)) {
        rw_note (0, 0, 0, "numeric_limits<%s>::traps test disabled", tname);
        return numT ();
    }
 
    const bool traps = std::numeric_limits<numT>::traps;
 
    rw_info (0, 0, 0, "std::numeric_limits<%s>::traps = %b", tname, traps);
 
#ifdef SIGFPE
    std::signal (SIGFPE, handle_fpe);
#else   // if !defined (SIGFPE)
    if (!rw_warn (!traps, 0, lineno,
                  "SIGFPE not #defined and numeric_limits<%s>::traps == %b, "
                  "cannot test", tname, traps)) {
        return numT ();
    }
#endif   // SIGFPE
 
    numT result = numT ();
 
    // set the environment
    const int jumped = RW_SIGSETJMP (jmp_env, SIGFPE);
 
    volatile numT zero = numT (jumped);
    volatile numT one  = numT (1);
 
    bool trapped = false;
 
    if (jumped) {
        // setjmp() call above returned from the SIGFPE handler
        // as a result of a floating point exception triggered
        // by the division by zero in the else block below
        result = zero / one;
 
        trapped = true;
    }
    else {
        // setjmp() call above returned after setting up the jump
        // environment; see of division by zero traps (if so, it
        // will generate a SIGFPE which will be caught by the
        // signal hanlder above and execution will resume by
        // returning from setjmp() above again, but this time
        // with a non-zero value
        try_trap (one, zero, result, trapped);
    }
 
    rw_assert (trapped == traps, 0, lineno,
               "numeric_limits<%s>::traps == %b, got %b",
               tname,  trapped, traps);
 
    return result;
}
 
 
static int
run_test (int, char*[])
{
#define TEST(T, floating)   test_traps ((T)0, __LINE__, floating)
 
#ifndef _RWSTD_NO_NATIVE_BOOL
    TEST (bool, false);
#endif   // _RWSTD_NO_NATIVE_BOOL
 
    TEST (char, false);
    TEST (signed char, false);
    TEST (unsigned char, false);
 
    TEST (short, false);
    TEST (unsigned short, false);
    TEST (int, false);
    TEST (unsigned int, false);
    TEST (long, false);
    TEST (unsigned long, false);
 
#ifndef _RWSTD_NO_LONG_LONG
    TEST (_RWSTD_LONG_LONG, false);
    TEST (unsigned _RWSTD_LONG_LONG, false);
#endif   // _RWSTD_NO_LONG_LONG
 
#ifndef _RWSTD_NO_NATIVE_WCHAR_T
    TEST (wchar_t, false);
#endif   // _RWSTD_NO_NATIVE_WCHAR_T
 
    TEST (float, true);
    TEST (double, true);
 
#ifndef _RWSTD_NO_LONG_DOUBLE
    TEST (long double, true);
#endif   // _RWSTD_NO_LONG_DOUBLE
 
    return 0;
}
 
 
int main (int argc, char *argv[])
{
    return rw_test (argc, argv, __FILE__,
                    "lib.numeric.limits.members",
                    "traps data member",
                    run_test,
                    0, 0);
}