Let me document another "funny" bug that I ran into while trying to install
Net::SSLeay using nmake and VC2013: Even after installing openssl and
setting the OPENSSL_PREFIX environment variable, for some unknown reason
the build script was not able to find the libeay and ssleay libraries. You
would get these warnings:

Warning (mostly harmless): No library found for -libeay32
Warning (mostly harmless): No library found for -ssleay32

Followed by many hundreds of external symbol errors. This is because the
"link" command failed to actually link against the ssleay and libeay
libraries. `look Net::SSLeay` and re-run the link command, adding the paths
to those two .lib files:

link -out:blib\arch\auto\Net\SSLeay\SSLeay.dll -dll -nologo -nodefaultlib
-debug -opt:ref,icf -ltcg  -libpath:"c:\cpantest\perl5163\lib\CORE"
 -machine:AMD64 "/manifestdependency:type='Win32'
name='Microsoft.Windows.Common-Controls' version='6.0.0.0'
processorArchitecture='*' publicKeyToken='6595b64144ccf1df' language='*'"
SSLeay.obj   "C:\cpantest\perl5163\lib\CORE\perl516.lib" <SNIP> "C:\Program
Files (x86)\Microsoft Visual Studio 12.0\VC\LIB\amd64\msvcrt.lib"
"C:\openssl\lib\libeay32.lib" "C:\openssl\lib\ssleay32.lib" -def:SSLeay.def

then `nmake install` and install IO::Socket::SSL.

Regards,
Dan Collins

On Fri, Dec 19, 2014 at 5:30 PM, bulk88 <[email protected]> wrote:

> Reini Urban wrote:
>
>> On 12/19/2014 02:25 PM, A. Sinan Unur wrote:
>>
>>
>>> On Fri, Dec 19, 2014 at 3:00 PM, A. Sinan Unur <[email protected]> wrote:
>>>
>>>
>>>> On Fri, Dec 19, 2014 at 2:04 PM, A. Sinan Unur <[email protected]> wrote:
>>>>
>>>>
>>>>> On Fri, Dec 19, 2014 at 11:08 AM, Nigel Horne <[email protected]>
>>>>> wrote:
>>>>>
>>>>>
>>>>>> PS – it would help if the red column under the MSWin32 column of
>>>>>> http://matrix.cpantesters.org/?dist=POE-Component-SmokeBox+0.48
>>>>>> could be
>>>>>> addressed.
>>>>>>
>>>>>>
>>>>> OK, some more progress ... Here is the stack when t\backend\02_check.t
>>>> fails. We have a null pointer thing going on:
>>>>
>>>> First-chance exception at 0x0000000054BD04C7 (perl520.dll) in
>>>> perl.exe: 0xC0000005: Access violation writing location
>>>> 0x0000000000000000.
>>>> Unhandled exception at 0x0000000054BD04C7 (perl520.dll) in perl.exe:
>>>> 0xC0000005: Access violation writing location 0x0000000000000000.
>>>>
>>>>
>>> Hmmmmm .... Could it be related to:
>>>
>>> http://perl5.git.perl.org/perl.git/commitdiff/
>>> 1cbe4e6fdc25527a4e9930e2f6a96fea3834bfd1?hp=
>>> 8fe523b46877224b0d8f3bd5ea78396ff0b4242d
>>>
>>> SvREFCNT_dec_NN in SDBM
>>>
>>> VC 2003 optimizer didn't catch it because SvREFCNT_dec is rarely inlined
>>> on -O1
>>>
>>>
>>
>> Yes, bulk88's _NN patch is wrong. You need to catch the NULL here
>>
>>
>
> My patch was correct. "if(pointer){if(!pointer) {unreachable();}}" If
> suddenly unreachable() can be called, you need to submit a bug report to
> your CC vendor.
>
> The callstack is from 5.20.*, that p5 core patch is in 5.21.7. Its not on
> Unur's machine. Since the callstack had symbols, it is easy to figure out
> what went wrong.
>
> perl520.dll!VMem::Free(void * pMem) Line 202    C++
> perl520.dll!Perl_safesysfree(void * where) Line 360    C
> SDBM_File.dll!XS_SDBM_File_DESTROY(interpreter * my_perl, cv * cv) Line
> 262    C
> perl520.dll!Perl_pp_entersub(interpreter * my_perl) Line 2797    C
> ..........
> perl520.dll!perl_destruct(interpreter * my_perl) Line 807    C
> perl520.dll!win32_start_child(void * arg) Line 1796    C++
>
> Line 202, http://perl5.git.perl.org/perl.git/blob/HEAD:/win32/vmem.h#l202
> 197         if (ptr->owner != this) {
> 198             if (ptr->owner) {
> 199 #if 1
> 200                 int *nowhere = NULL;
> 201                 Perl_warn_nocontext("Free to wrong pool %p not
> %p",this,ptr->owner);
> 202                 *nowhere = 0; /* this segfault is deliberate, 203
>                             so you can see the stack trace */
> 204 #else
> 205                 ptr->owner->Free(pMem); 206 #endif
> 207             }
>
> SDBM_File is ithread and therefore psuedofork unsafe. It either needs a
> CLONE method in PP, svt_dup magic, and/or MY_CXT or to fatally die if a
> resource can't be duplicated and a CLONE is attempted.
>
> void
> sdbm_DESTROY(db)
>         SDBM_File       db
>         CODE:
>         if (db) {
>             int i = store_value;
>             sdbm_close(db->dbp);
>             do {
>                 if (db->filter[i])
>                     SvREFCNT_dec(db->filter[i]);
>             } while (i-- > 0);
>             safefree(db) ;
>         }
> ------------------------------------------
> SDBM_File               T_PTROBJ
> ------------------------------------------
> T_PTROBJ
>         if (SvROK($arg) && sv_derived_from($arg, \"${ntype}\")) {
>             IV tmp = SvIV((SV*)SvRV($arg));
>             $var = INT2PTR($type,tmp);
>         }
>         else
>             Perl_croak(aTHX_ \"%s: %s is not of type %s\",
>                         ${$ALIAS?\q[GvNAME(CvGV(cv))]:\qq[\"$pname\"]},
>                         \"$var\", \"$ntype\")
> ------------------------------------------
>
> SDBM_File
> sdbm_TIEHASH(dbtype, filename, flags, mode, pagname=NULL)
>         char *          dbtype
>         char *          filename
>         int             flags
>         int             mode
>         char *          pagname
>         CODE:
>         {
>             DBM *       dbp ;
>
>             RETVAL = NULL ;
>             if (pagname == NULL) {
>                 dbp = sdbm_open(filename, flags, mode);
>             }
>             else {
>                 dbp = sdbm_prep(filename, pagname, flags, mode);
>             }
>             if (dbp) {
>                 RETVAL = (SDBM_File)safecalloc(1, sizeof(SDBM_File_type));
>                 RETVAL->dbp = dbp ;
>             }
>                 }
>         OUTPUT:
>           RETVAL
> -------------------------------------------
> Yep, thread unsafe. If instead of using a blessed SVIV, it used a blessed
> SVPV and sv_grow/SvCUR_set, perl would automatically dup the memory block,
> but it would still be unsafe since the memory block is
>
> typedef struct {
>         DBM *   dbp ;
>         SV *    filter[4];
>         int     filtering ;
>         } SDBM_File_type;
>
> and it keeps SV*s there that Perl doesn't know about at CLONE time.
>
> Now even if SDBM_File_type was replaced with an AV, and AvARRAY and SvIVX
> for speed, you will still crash when
>
> ------------------------------------------
>             sdbm_close(db->dbp);
> ------------------------------------------
>
> runs twice on the same "DBM *   dbp". I dont see how this can ever be
> thread safe. IMO setting the blessed SVIV object to 0 during a CLONE is the
> only thing to do, unless you can duplicate the data/resources inside DBM *
> through the DBMS's API. SDBM would fail with valgrind and ithreads on Linux
> with a double free anyway inside sdbm_close().
>
>

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