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<a href="https://gitlab.com/Courmisch">Remi Denis-Courmont</a>
commented:
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<p dir="auto">I doubt that. Normally you need the flag to be set atomically in multi-thread context. That's the whole point of using *_CLOEXEC flags.</p>
<p dir="auto">Otherwise there is a race if a thread calls <code>fork()</code> between the <code>fopen()</code> and the <code>set_close_exec()</code> flag. <code>fork()</code> copies the flag at the time of forking.</p>
<p dir="auto">For instance:</p>
<ul dir="auto">
<li>Thread A calls <code>gnutls_handshake()</code>... which opens the master key log file wit <code>fopen()</code>.
<ul>
<li>This creates a new file descriptor (without close-on-exec flag).</li>
</ul>
</li>
<li>Thread B calls <code>fork()</code> from application code.
<ul>
<li>The file descriptor is copied into the child process (also without the close-on-exec flag).</li>
</ul>
</li>
<li>Thread A calls <code>set_cloese_exec()</code> (or directly <code>fcntl()</code>).
<ul>
<li>This sets the flag on the parent process FD, but not the child process FD.</li>
</ul>
</li>
<li>Child process calls <code>execv()</code> oblivious to the FD. The master key log FD is leaked to the child process.</li>
</ul>
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