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POconstraints when dynamically loading a shared object from another shared object?
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  1. POconstraints when dynamically loading a shared object from another shared object?
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    copied!<p>I'm dynamically loading (whith <code>dlopen()</code>) a shared object (named <code>libprofile1.so</code>) from <code>main</code>. </p> <p>In <code>libprofile1.so</code> I have defined factory function <code>CreateProfile</code> and class <code>Profile</code>. <code>CreateProfile</code> function creates an instance of <code>Profile</code> class and returns a pointer to it. Class <code>Profile</code> has a method <code>pMethod</code>. </p> <p>In main, after loading <code>libprofile1.so</code>, I'm calling <code>CreateProfile</code> method which returns the pointer to the object of <code>Profile</code> class (call it <code>p</code>).<br> Afterwards, I'm calling <code>pMethod</code> method against object <code>p</code> (<code>p-&gt;pMethod</code>). In this method I'm dynamically loading other shared object (<code>libdatasources.so</code>). </p> <p>In this shared object I have a factory function <code>CreateDataSource</code>and class <code>DataSource</code>.<br> <code>CreateDataSource</code> function creates an instance of <code>DataSource</code> class and returns a pointer to it. <code>DataSource</code> class has method <code>dsMethod</code>. </p> <p>As you can notice, structures of both shared objects are similar.</p> <p>From <code>pMethod</code> after loading <code>libdatasources.so</code> I'm calling <code>CreateDataSource</code> method, which returns me a pointer to an instance of <code>DataSource</code> class, call it <code>ds</code>. Then I'm calling <code>dsMethod</code> of <code>ds</code> object<br> (<code>ds-&gt;dsMethod</code>).</p> <hr> <p>Now, the problem is following. </p> <p>When I try to call <code>dsMethod</code> of <code>ds</code> object, shared object that I'm first loading (<code>libprofile1.so</code>) doesn't load. Actually <code>dlopen()</code> returns <code>NULL</code>. When I read <code>dlerror</code> after <code>dlopen</code> I get:</p> <p><code>./libprofile1.so: undefined symbol: _ZN18DataSource13dsMethod</code></p> <p>So if I have a call <code>ds-&gt;Method</code>, than first shared object doesn't load!<br> If I comment out call <code>ds-&gt;dsMethod</code> from the source, then my <code>libprofile1.so</code> and <code>libdatasources.so</code> are loaded without any problems.<br> I don't see the connection between the call of a method from the second SO, with loading first SO???</p> <p>Maybe I don't know, but are there any constraints when dynamically loading a shared object, from a shared object that's also been dynamically loaded?</p> <p>Btw, <code>dlopen</code> is used with <code>RTLD_NOW|RTLD_GLOBAL</code>. I tried with <code>RTLD_LAZY</code>, but still the same problem.</p> <p><strong>UPDATE:</strong></p> <p>Libraries are built in Eclipse. Options for G++ compiler and linker are the same for both libraries.<br> Here are G++ compiler:</p> <pre><code>-O0 -g3 -Wall -c -fmessage-length=0 </code></pre> <p>and G++ linker:</p> <pre><code>-shared </code></pre> <p>options, pasted from <code>Project Properties -&gt; Settings -&gt; Tool Settings</code></p> <p>Thanks in advance.</p>
 

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