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Date: Mon, 12 May 2008 19:14:55 -0700 (PDT)
From: "Eric Lemings (JIRA)" <jira@apache.org>
To: issues@stdcxx.apache.org
Subject: [jira] Created: (STDCXX-931) [gcc/Darwin] 0.printf test aborts with
 bus error
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[gcc/Darwin] 0.printf test aborts with bus error
------------------------------------------------

                 Key: STDCXX-931
                 URL: https://issues.apache.org/jira/browse/STDCXX-931
             Project: C++ Standard Library
          Issue Type: Bug
          Components: Test Driver
    Affects Versions: 4.2.1
         Environment: Darwin host.local 9.2.2 Darwin Kernel Version 9.2.2: Tue Mar  4 21:17:34 PST 2008; root:xnu-1228.4.31~1/RELEASE_I386 i386
            Reporter: Eric Lemings
             Fix For: 4.2.x


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.
{{noformat}}
# 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) - reint
erpret_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) - reinterpre
t_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"
{{noformat}}

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