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<ul class="crumbs"><li><a href="../webs.html">&#9733;</a></li><li><a href="index.html">problems</a></li><li><a href="index.html#2">Chapter 2: Problems</a></li><li><b>Problems, Level 0</b></li></ul><p class="purpose">To handle fatal errors.</p>
<p class="inwebparagraph"><a id="SP1"></a><b>&#167;1. </b>In my beginning is my end: this lowest level of the error-handling system
deals with systemic collapses.
</p>
<pre class="display">
<span class="identifier">text_stream</span><span class="plain"> </span><span class="identifier">problems_file_struct</span><span class="plain">; </span> <span class="comment">The actual report of Problems file</span>
<span class="identifier">text_stream</span><span class="plain"> *</span><span class="identifier">problems_file</span><span class="plain"> = &amp;</span><span class="identifier">problems_file_struct</span><span class="plain">; </span> <span class="comment">The actual report of Problems file</span>
<span class="identifier">text_stream</span><span class="plain"> *</span><span class="identifier">probl</span><span class="plain"> = </span><span class="identifier">NULL</span><span class="plain">; </span> <span class="comment">Current destination of problem message text</span>
<span class="reserved">int</span><span class="plain"> </span><span class="identifier">internal_error_thrown</span><span class="plain"> = </span><span class="identifier">FALSE</span><span class="plain">;</span>
<span class="reserved">int</span><span class="plain"> </span><span class="identifier">it_is_not_worth_adding</span><span class="plain"> = </span><span class="identifier">FALSE</span><span class="plain">; </span> <span class="comment">To suppress the "It may be worth adding..."</span>
<span class="reserved">int</span><span class="plain"> </span><span class="identifier">crash_on_all_errors</span><span class="plain"> = </span><span class="identifier">FALSE</span><span class="plain">;</span>
<span class="identifier">text_stream</span><span class="plain"> *</span><span class="identifier">sigil_of_required_problem</span><span class="plain"> = </span><span class="identifier">NULL</span><span class="plain">;</span>
<span class="reserved">int</span><span class="plain"> </span><span class="identifier">sigil_of_required_problem_found</span><span class="plain"> = </span><span class="identifier">FALSE</span><span class="plain">;</span>
<span class="reserved">void</span><span class="plain"> </span><span class="functiontext">Problems::Fatal::require</span><span class="plain">(</span><span class="identifier">text_stream</span><span class="plain"> *</span><span class="identifier">sigil</span><span class="plain">) {</span>
<span class="identifier">sigil_of_required_problem</span><span class="plain"> = </span><span class="identifier">Str::duplicate</span><span class="plain">(</span><span class="identifier">sigil</span><span class="plain">);</span>
<span class="plain">}</span>
<span class="reserved">void</span><span class="plain"> </span><span class="functiontext">Problems::Fatal::exit</span><span class="plain">(</span><span class="reserved">int</span><span class="plain"> </span><span class="identifier">code</span><span class="plain">) {</span>
<span class="reserved">if</span><span class="plain"> ((</span><span class="identifier">sigil_of_required_problem</span><span class="plain">) &amp;&amp; (</span><span class="identifier">sigil_of_required_problem_found</span><span class="plain"> == </span><span class="identifier">FALSE</span><span class="plain">))</span>
<span class="identifier">exit</span><span class="plain">(0); </span> <span class="comment">so that the problem test case will fail in <code class="display"><span class="extract">intest</span></code></span>
<span class="identifier">exit</span><span class="plain">(</span><span class="identifier">code</span><span class="plain">);</span>
<span class="plain">}</span>
<span class="reserved">void</span><span class="plain"> </span><span class="functiontext">Problems::Fatal::issue</span><span class="plain">(</span><span class="reserved">char</span><span class="plain"> *</span><span class="identifier">message</span><span class="plain">) {</span>
<span class="identifier">WRITE_TO</span><span class="plain">(</span><span class="identifier">STDERR</span><span class="plain">, </span><span class="identifier">message</span><span class="plain">);</span>
<span class="identifier">WRITE_TO</span><span class="plain">(</span><span class="identifier">STDERR</span><span class="plain">, </span><span class="string">"\</span><span class="plain">n</span><span class="string">"</span><span class="plain">);</span>
<span class="identifier">STREAM_FLUSH</span><span class="plain">(</span><span class="identifier">STDERR</span><span class="plain">);</span>
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">crash_on_all_errors</span><span class="plain">) </span><span class="functiontext">Problems::Fatal::force_crash</span><span class="plain">();</span>
<span class="functiontext">Problems::Fatal::exit</span><span class="plain">(2);</span>
<span class="plain">}</span>
<span class="reserved">void</span><span class="plain"> </span><span class="functiontext">Problems::Fatal::issue_t</span><span class="plain">(</span><span class="reserved">char</span><span class="plain"> *</span><span class="identifier">message</span><span class="plain">, </span><span class="reserved">char</span><span class="plain"> *</span><span class="identifier">fn</span><span class="plain">) {</span>
<span class="identifier">WRITE_TO</span><span class="plain">(</span><span class="identifier">STDERR</span><span class="plain">, </span><span class="identifier">message</span><span class="plain">);</span>
<span class="identifier">WRITE_TO</span><span class="plain">(</span><span class="identifier">STDERR</span><span class="plain">, </span><span class="string">"\</span><span class="plain">n</span><span class="string">Offending filename: &lt;%s&gt;\</span><span class="plain">n</span><span class="string">"</span><span class="plain">, </span><span class="identifier">fn</span><span class="plain">);</span>
<span class="identifier">STREAM_FLUSH</span><span class="plain">(</span><span class="identifier">STDERR</span><span class="plain">);</span>
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">crash_on_all_errors</span><span class="plain">) </span><span class="functiontext">Problems::Fatal::force_crash</span><span class="plain">();</span>
<span class="functiontext">Problems::Fatal::exit</span><span class="plain">(2);</span>
<span class="plain">}</span>
<span class="reserved">void</span><span class="plain"> </span><span class="functiontext">Problems::Fatal::filename_related</span><span class="plain">(</span><span class="reserved">char</span><span class="plain"> *</span><span class="identifier">message</span><span class="plain">, </span><span class="identifier">filename</span><span class="plain"> *</span><span class="identifier">F</span><span class="plain">) {</span>
<span class="identifier">WRITE_TO</span><span class="plain">(</span><span class="identifier">STDERR</span><span class="plain">, </span><span class="identifier">message</span><span class="plain">);</span>
<span class="identifier">WRITE_TO</span><span class="plain">(</span><span class="identifier">STDERR</span><span class="plain">, </span><span class="string">"\</span><span class="plain">n</span><span class="string">Offending filename: &lt;%f&gt;\</span><span class="plain">n</span><span class="string">"</span><span class="plain">, </span><span class="identifier">F</span><span class="plain">);</span>
<span class="identifier">STREAM_FLUSH</span><span class="plain">(</span><span class="identifier">STDERR</span><span class="plain">);</span>
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">crash_on_all_errors</span><span class="plain">) </span><span class="functiontext">Problems::Fatal::force_crash</span><span class="plain">();</span>
<span class="functiontext">Problems::Fatal::exit</span><span class="plain">(2);</span>
<span class="plain">}</span>
</pre>
<p class="inwebparagraph"></p>
<p class="endnote">The function Problems::Fatal::require appears nowhere else.</p>
<p class="endnote">The function Problems::Fatal::exit is used in <a href="#SP2">&#167;2</a>, 2/pl3 (<a href="2-pl3.html#SP2">&#167;2</a>, <a href="2-pl3.html#SP12">&#167;12</a>).</p>
<p class="endnote">The function Problems::Fatal::issue appears nowhere else.</p>
<p class="endnote">The function Problems::Fatal::issue_t appears nowhere else.</p>
<p class="endnote">The function Problems::Fatal::filename_related is used in 1/tlm (<a href="1-tlm.html#SP1">&#167;1</a>).</p>
<p class="inwebparagraph"><a id="SP2"></a><b>&#167;2. </b>Fatal errors are not necessarily a bad thing. When tracking down why
NI issues certain problem messages (especially internal errors) it can be
useful to provoke a deliberate crash of the application, in order to
get a stack backtrace into the GNU debugger <code class="display"><span class="extract">gdb</span></code> (and/or onto the system
console logs). We can force this using the following variables (which main
sets with the command-line switch "-gdb").
</p>
<pre class="display">
<span class="reserved">void</span><span class="plain"> </span><span class="functiontext">Problems::Fatal::force_crash</span><span class="plain">(</span><span class="reserved">void</span><span class="plain">) {</span>
<span class="identifier">STREAM_FLUSH</span><span class="plain">(</span><span class="identifier">STDOUT</span><span class="plain">);</span>
<span class="identifier">STREAM_FLUSH</span><span class="plain">(</span><span class="identifier">DL</span><span class="plain">);</span>
<span class="identifier">WRITE_TO</span><span class="plain">(</span><span class="identifier">STDERR</span><span class="plain">,</span>
<span class="string">"*** Intentionally crashing to force stack backtrace to console logs ***\</span><span class="plain">n</span><span class="string">"</span><span class="plain">);</span>
<span class="identifier">STREAM_FLUSH</span><span class="plain">(</span><span class="identifier">STDERR</span><span class="plain">);</span>
<span class="identifier">parse_node</span><span class="plain"> *</span><span class="identifier">PN</span><span class="plain"> = </span><span class="identifier">NULL</span><span class="plain">; </span><span class="identifier">LOG</span><span class="plain">(</span><span class="string">"$T"</span><span class="plain">, </span><span class="identifier">PN</span><span class="plain">-&gt;</span><span class="identifier">next</span><span class="plain">);</span>
<span class="functiontext">Problems::Fatal::exit</span><span class="plain">(1);</span>
<span class="plain">}</span>
</pre>
<p class="inwebparagraph"></p>
<p class="endnote">The function Problems::Fatal::force_crash is used in <a href="#SP1">&#167;1</a>, 2/pl2 (<a href="2-pl2.html#SP9">&#167;9</a>), 2/pl3 (<a href="2-pl3.html#SP2">&#167;2</a>).</p>
<hr class="tocbar">
<ul class="toc"><li><i>(This section begins Chapter 2: Problems.)</i></li><li><a href="2-pl1.html">Continue with 'Problems, Level 1'</a></li></ul><hr class="tocbar">
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