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POCrash on checking ERRSV when embedding Perl in C++ (Win32)
 

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  1. POCrash on checking ERRSV when embedding Perl in C++ (Win32)
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    <p>I am embedding the Perl interpreter (v 5.16.3) in my Visual C++ based code (on Windows 7). The intention is to invoke a user-written subroutine in Perl from my C++ program. </p> <p>The overall structure of the C++ code to invoke Perl can be thought of as follows:</p> <pre><code>perl_alloc() perl_construct() perl_parse() dSP int result = call_argv(funcName, G_ARRAY|G_EVAL|G_KEEPERR, params); if (SvTRUE (ERRSV)) // &lt;-- crashes here { : } </code></pre> <p>This code crashes at runtime on the marked line. The problem stems from accessing ERRSV, which would be a macro. Doing some troubleshooting, I found out that the troublemaker is the following attribute:</p> <pre><code>vTHX-&gt;Ierrgv </code></pre> <p>i.e., <code>Ierrgv</code> is NULL in my case.</p> <p>If I comment out this error checking (i.e., <code>SvTRUE</code>), the code itself works fine, and I know that my Perl script gets executed as well. I can even retrieve the return parameters from the called subroutine!</p> <p>Can someone tell me <strong>why <code>Ierrgv</code> would be NULL, and what exactly that means?</strong></p> <p>EDIT:</p> <p>Making a small change apparently fixes the problem but without detailed insight into <code>Ierrgv</code> usage, I am not cofident to consider it as a solution:</p> <pre><code>int result = call_argv(funcName, G_ARRAY|G_EVAL|G_KEEPERR, params); if ( (result==0) &amp;&amp; (SvTRUE (ERRSV) ) // &lt;-- doesn't crash here { : } </code></pre> <p>The added check on <code>result</code> ensures that we evaluate <code>ERRSV</code> only when <code>result</code> is zero. As I said earlier, apparently this fixes the problem.</p>
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    1. COI have a similar issue that fails in v5.14.2, but works in v5.12.4 and v5.17.6. I'm very interested if there's an explanation and a solution.
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    2. COIt would help to have a minimal runnable demonstration of the problem
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