[gcc/Darwin] 0.printf test aborts with bus error

• Key: STDCXX-931
• Type: Bug
• Status: Open
• Priority: Minor
• Assignee: Eric Lemings
• Reporter: Eric Lemings
• Component/s: Test Driver
• Affects Version/s: 4.2.1
• Fix Version/s: 4.2.2

Description

The test_string() function in the 0.printf test calls bad_address() to generate an invalid address. This address is eventually passed to the __rw::__rw_memattr() function which uses the pointer value, specifically 0x20, as the pointer value to the memchr() C library function which promptly aborts the program. The invalid pointer should be caught before calling such C library functions which usually expect valid pointers. Suspect the proliferous conditional code within the function or some other unaccounted platform dependency. The preprocessed Darwin source for __rw_memattr() is shown below.

# 97 "/stdcxx/branches/4.2.x/src/memattr.cpp"
namespace __rw {

 long
__rw_memattr (const void *addr, unsigned long nbytes, int attr)
{
    ((void)&attr);
    const int errno_save = (*__error());
    static const unsigned long pgsz = size_t (sysconf (29));
    caddr_t const page =
        reinterpret_cast< caddr_t >(reinterpret_cast< unsigned long >(addr) & ~(pgsz - 1))
;
    unsigned long npages = nbytes ? nbytes / pgsz + 1 : 0;
    for (size_t i = 0; i < npages; ++i) {
        const caddr_t next = reinterpret_cast< char* >(page) + i * pgsz;
# 177 "/stdcxx/branches/4.2.x/src/memattr.cpp"
        const int advice = 3;
        if (-1 == madvise (next, 1, advice)) {
            const int err = (*__error());
            (*__error()) = errno_save;
            bool bad_address;
# 198 "/stdcxx/branches/4.2.x/src/memattr.cpp"
            bad_address = !(0 == err || 22 == err);
            if (bad_address)
                return next == page ? -1 : ( reinterpret_cast< const char* >(next) - reinterpret_cast< const char* >(addr));
        }

        if (0xffffffffUL == nbytes) {
# 219 "/stdcxx/branches/4.2.x/src/memattr.cpp"
            const unsigned long maxpage =
                next == page ? pgsz - ( reinterpret_cast< const char* >(addr) - reinterpret_cast< const char* >(next)) : pgsz;

            const void* const pnul =
                memchr (next == page ? addr : next, '\0', maxpage);
            if (pnul) {
                nbytes = ( reinterpret_cast< const char* >(pnul) - reinterpret_cast< const char* >(addr));
                npages = nbytes / pgsz + 1;
                break;
            }
        }
    }

    return static_cast< long >(nbytes);
# 262 "/stdcxx/branches/4.2.x/src/memattr.cpp"