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<a href="https://gitlab.com/asosedkin">Alexander Sosedkin</a>
commented on a
discussion on <a href="https://gitlab.com/gnutls/gnutls/-/merge_requests/1483#note_721370433">lib/priority.c</a>:
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<pre style="margin: 0;"> <span id="LC1443" class="line" lang="c"><span class="cm" style="color: #998; font-style: italic;"> * allow it to be updated without restarting</span></span>
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<pre style="margin: 0;"> <span id="LC1444" class="line" lang="c"><span class="cm" style="color: #998; font-style: italic;"> * all applications</span></span>
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<pre style="margin: 0;"> <span id="LC1445" class="line" lang="c"><span class="cm" style="color: #998; font-style: italic;"> */</span></span>
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<pre style="margin: 0;">+<span id="LC1446" class="line" lang="c"> <span class="n" style="color: #333;">GNUTLS_STATIC_MUTEX_LOCK</span><span class="p">(</span><span class="n" style="color: #333;">system_wide_config_mutex</span><span class="p">);</span></span>
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<pre style="margin: 0;"> <span id="LC1447" class="line" lang="c"> <span class="n" style="color: #333;">_gnutls_update_system_priorities</span><span class="p">();</span></span>
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<p dir="auto">Not necessarily? The current guarantee is "load a config no older than the moment we invoke the function", what would that change upgrade it to?</p>
<p dir="auto">I'd propose (getting progressively more frivolous with pseudocode):</p>
<pre class="code highlight js-syntax-highlight language-plaintext" lang="plaintext" v-pre="true" style="background-color: #fff; font-family: monospace; font-size: 90%; -premailer-cellpadding: 0; -premailer-cellspacing: 0; -premailer-width: 100%; margin: 0;"><code><span id="LC1" class="line" lang="plaintext">stat(&mtime);</span>
<span id="LC2" class="line" lang="plaintext">rdlock();</span>
<span id="LC3" class="line" lang="plaintext">if (init_indicator && mtime == last_mtime) { unlock(); return; }</span>
<span id="LC4" class="line" lang="plaintext">wrlock();</span>
<span id="LC5" class="line" lang="plaintext">if (mtime == last_mtime) { unlock(); return; } // other thread beat us to loading with the same mtime</span>
<span id="LC6" class="line" lang="plaintext">...</span>
<span id="LC7" class="line" lang="plaintext">last_mtime = mtime;</span>
<span id="LC8" class="line" lang="plaintext">unlock();</span></code></pre>
<p dir="auto">which is a middle-ground that'd still catch some updates during mass-waiting (just not the ones that happened after the last updater was started), yet stick to a single stat call.</p>
<p dir="auto">All this talk makes me wonder what software does and does not actually bother with atomically replacing gnutls system configs =)</p>
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