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Graham Nelson 73348dc86d Added locale-setting at the command line
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
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<title>Error Messages</title>
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<div class="breadcrumbs">
<ul class="crumbs"><li><a href="../index.html">Home</a></li><li><a href="index.html">foundation</a></li><li><a href="index.html#3">Chapter 3: The Operating System</a></li><li><b>Error Messages</b></li></ul></div>
<p class="purpose">A basic system for command-line tool error messages.</p>
<ul class="toc"><li><a href="3-em.html#SP1">&#167;1. Errors handler</a></li><li><a href="3-em.html#SP2">&#167;2. Error messages</a></li><li><a href="3-em.html#SP4">&#167;4. Deliberately crashing</a></li><li><a href="3-em.html#SP5">&#167;5. Survivable errors</a></li></ul><hr class="tocbar">
<p class="commentary firstcommentary"><a id="SP1"></a><b>&#167;1. Errors handler. </b>The user can provide a routine to deal with error messages before they're
issued. If this returns <span class="extract"><span class="extract-syntax">FALSE</span></span>, nothing is printed to <span class="extract"><span class="extract-syntax">stderr</span></span>.
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="reserved-syntax">int</span><span class="plain-syntax"> (*</span><span class="identifier-syntax">errors_handler</span><span class="plain-syntax">)(</span><span class="reserved-syntax">text_stream</span><span class="plain-syntax"> *, </span><span class="reserved-syntax">int</span><span class="plain-syntax">) = </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">;</span>
<span class="reserved-syntax">void</span><span class="plain-syntax"> (*</span><span class="identifier-syntax">internal_errors_handler</span><span class="plain-syntax">)(</span><span class="reserved-syntax">void</span><span class="plain-syntax"> *, </span><span class="reserved-syntax">char</span><span class="plain-syntax"> *, </span><span class="reserved-syntax">char</span><span class="plain-syntax"> *, </span><span class="reserved-syntax">int</span><span class="plain-syntax">) = </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">;</span>
<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">Errors::set_handler</span><span class="plain-syntax">(</span><span class="reserved-syntax">int</span><span class="plain-syntax"> (*</span><span class="identifier-syntax">f</span><span class="plain-syntax">)(</span><span class="reserved-syntax">text_stream</span><span class="plain-syntax"> *, </span><span class="reserved-syntax">int</span><span class="plain-syntax">)) {</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">errors_handler</span><span class="plain-syntax"> = </span><span class="identifier-syntax">f</span><span class="plain-syntax">;</span>
<span class="plain-syntax">}</span>
<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">Errors::set_internal_handler</span><span class="plain-syntax">(</span><span class="reserved-syntax">void</span><span class="plain-syntax"> (*</span><span class="identifier-syntax">f</span><span class="plain-syntax">)(</span><span class="reserved-syntax">void</span><span class="plain-syntax"> *, </span><span class="reserved-syntax">char</span><span class="plain-syntax"> *, </span><span class="reserved-syntax">char</span><span class="plain-syntax"> *, </span><span class="reserved-syntax">int</span><span class="plain-syntax">)) {</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">internal_errors_handler</span><span class="plain-syntax"> = </span><span class="identifier-syntax">f</span><span class="plain-syntax">;</span>
<span class="plain-syntax">}</span>
<span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">problem_count</span><span class="plain-syntax"> = </span><span class="constant-syntax">0</span><span class="plain-syntax">;</span>
<span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="function-syntax">Errors::have_occurred</span><button class="popup" onclick="togglePopup('usagePopup1')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup1">Usage of <span class="code-font"><span class="function-syntax">Errors::have_occurred</span></span>:<br/>Streams - <a href="2-str.html#SP37">&#167;37</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">void</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">problem_count</span><span class="plain-syntax"> &gt; </span><span class="constant-syntax">0</span><span class="plain-syntax">) </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="constant-syntax">TRUE</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="constant-syntax">FALSE</span><span class="plain-syntax">;</span>
<span class="plain-syntax">}</span>
<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">Errors::issue</span><button class="popup" onclick="togglePopup('usagePopup2')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup2">Usage of <span class="code-font"><span class="function-syntax">Errors::issue</span></span>:<br/><a href="3-em.html#SP2">&#167;2</a>, <a href="3-em.html#SP6">&#167;6</a>, <a href="3-em.html#SP7">&#167;7</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">text_stream</span><span class="plain-syntax"> *</span><span class="identifier-syntax">message</span><span class="plain-syntax">, </span><span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">fatality</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">rv</span><span class="plain-syntax"> = </span><span class="constant-syntax">TRUE</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">errors_handler</span><span class="plain-syntax">) </span><span class="identifier-syntax">rv</span><span class="plain-syntax"> = (*</span><span class="identifier-syntax">errors_handler</span><span class="plain-syntax">)(</span><span class="identifier-syntax">message</span><span class="plain-syntax">, </span><span class="identifier-syntax">fatality</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">rv</span><span class="plain-syntax">) </span><span class="identifier-syntax">WRITE_TO</span><span class="plain-syntax">(</span><span class="constant-syntax">STDERR</span><span class="plain-syntax">, </span><span class="string-syntax">"%S"</span><span class="plain-syntax">, </span><span class="identifier-syntax">message</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">fatality</span><span class="plain-syntax">) </span><a href="3-em.html#SP4" class="function-link"><span class="function-syntax">Errors::die</span></a><span class="plain-syntax">(); </span><span class="reserved-syntax">else</span><span class="plain-syntax"> </span><span class="identifier-syntax">problem_count</span><span class="plain-syntax">++;</span>
<span class="plain-syntax">}</span>
</pre>
<p class="commentary firstcommentary"><a id="SP2"></a><b>&#167;2. Error messages. </b>Ah, they kill you; or they don't. The fatal kind cause an exit code of 2, to
distinguish this from a proper completion in which non-fatal errors occur.
These two routines (alone) can be caused by failures of the memory allocation
or streams systems, and therefore must be written with a little care to use
the temporary stream, not some other string which might need fresh allocation.
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">Errors::fatal</span><button class="popup" onclick="togglePopup('usagePopup3')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup3">Usage of <span class="code-font"><span class="function-syntax">Errors::fatal</span></span>:<br/>Memory - <a href="2-mmr.html#SP11_1">&#167;11.1</a>, <a href="2-mmr.html#SP15">&#167;15</a>, <a href="2-mmr.html#SP16_1">&#167;16.1</a><br/>Locales - <a href="2-lcl.html#SP2">&#167;2</a>, <a href="2-lcl.html#SP5">&#167;5</a><br/>Streams - <a href="2-str.html#SP32">&#167;32</a>, <a href="2-str.html#SP34_1">&#167;34.1</a>, <a href="2-str.html#SP35_3">&#167;35.3</a><br/>Command Line Arguments - <a href="3-cla.html#SP8">&#167;8</a><br/>C Strings - <a href="4-cst.html#SP3">&#167;3</a><br/>Binary Files - <a href="6-bf.html#SP9">&#167;9</a><br/>Build Files - <a href="8-bf.html#SP7">&#167;7</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">char</span><span class="plain-syntax"> *</span><span class="identifier-syntax">message</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">TEMPORARY_TEXT</span><span class="plain-syntax">(</span><span class="identifier-syntax">ERM</span><span class="plain-syntax">)</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">WRITE_TO</span><span class="plain-syntax">(</span><span class="identifier-syntax">ERM</span><span class="plain-syntax">, </span><span class="string-syntax">"%s: fatal error: %s\n"</span><span class="plain-syntax">, </span><span class="identifier-syntax">PROGRAM_NAME</span><span class="plain-syntax">, </span><span class="identifier-syntax">message</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><a href="3-em.html#SP1" class="function-link"><span class="function-syntax">Errors::issue</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">ERM</span><span class="plain-syntax">, </span><span class="constant-syntax">TRUE</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">DISCARD_TEXT</span><span class="plain-syntax">(</span><span class="identifier-syntax">ERM</span><span class="plain-syntax">)</span>
<span class="plain-syntax">}</span>
<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">Errors::fatal_with_C_string</span><button class="popup" onclick="togglePopup('usagePopup4')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup4">Usage of <span class="code-font"><span class="function-syntax">Errors::fatal_with_C_string</span></span>:<br/><a href="3-em.html#SP3">&#167;3</a><br/>Memory - <a href="2-mmr.html#SP25_1">&#167;25.1</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">char</span><span class="plain-syntax"> *</span><span class="identifier-syntax">message</span><span class="plain-syntax">, </span><span class="reserved-syntax">char</span><span class="plain-syntax"> *</span><span class="identifier-syntax">parameter</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">TEMPORARY_TEXT</span><span class="plain-syntax">(</span><span class="identifier-syntax">ERM</span><span class="plain-syntax">)</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">WRITE_TO</span><span class="plain-syntax">(</span><span class="identifier-syntax">ERM</span><span class="plain-syntax">, </span><span class="string-syntax">"%s: fatal error: "</span><span class="plain-syntax">, </span><span class="identifier-syntax">PROGRAM_NAME</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">WRITE_TO</span><span class="plain-syntax">(</span><span class="identifier-syntax">ERM</span><span class="plain-syntax">, </span><span class="identifier-syntax">message</span><span class="plain-syntax">, </span><span class="identifier-syntax">parameter</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">WRITE_TO</span><span class="plain-syntax">(</span><span class="identifier-syntax">ERM</span><span class="plain-syntax">, </span><span class="string-syntax">"\n"</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><a href="3-em.html#SP1" class="function-link"><span class="function-syntax">Errors::issue</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">ERM</span><span class="plain-syntax">, </span><span class="constant-syntax">TRUE</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">DISCARD_TEXT</span><span class="plain-syntax">(</span><span class="identifier-syntax">ERM</span><span class="plain-syntax">)</span>
<span class="plain-syntax">}</span>
<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">Errors::fatal_with_text</span><button class="popup" onclick="togglePopup('usagePopup5')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup5">Usage of <span class="code-font"><span class="function-syntax">Errors::fatal_with_text</span></span>:<br/>Command Line Arguments - <a href="3-cla.html#SP8">&#167;8</a>, <a href="3-cla.html#SP11">&#167;11</a>, <a href="3-cla.html#SP13">&#167;13</a><br/>Bibliographic Data for Webs - <a href="8-bdfw.html#SP5">&#167;5</a><br/>Build Files - <a href="8-bf.html#SP6">&#167;6</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">char</span><span class="plain-syntax"> *</span><span class="identifier-syntax">message</span><span class="plain-syntax">, </span><span class="reserved-syntax">text_stream</span><span class="plain-syntax"> *</span><span class="identifier-syntax">parameter</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">TEMPORARY_TEXT</span><span class="plain-syntax">(</span><span class="identifier-syntax">ERM</span><span class="plain-syntax">)</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">WRITE_TO</span><span class="plain-syntax">(</span><span class="identifier-syntax">ERM</span><span class="plain-syntax">, </span><span class="string-syntax">"%s: fatal error: "</span><span class="plain-syntax">, </span><span class="identifier-syntax">PROGRAM_NAME</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">WRITE_TO</span><span class="plain-syntax">(</span><span class="identifier-syntax">ERM</span><span class="plain-syntax">, </span><span class="identifier-syntax">message</span><span class="plain-syntax">, </span><span class="identifier-syntax">parameter</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">WRITE_TO</span><span class="plain-syntax">(</span><span class="identifier-syntax">ERM</span><span class="plain-syntax">, </span><span class="string-syntax">"\n"</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><a href="3-em.html#SP1" class="function-link"><span class="function-syntax">Errors::issue</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">ERM</span><span class="plain-syntax">, </span><span class="constant-syntax">TRUE</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">DISCARD_TEXT</span><span class="plain-syntax">(</span><span class="identifier-syntax">ERM</span><span class="plain-syntax">)</span>
<span class="plain-syntax">}</span>
<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">Errors::fatal_with_file</span><button class="popup" onclick="togglePopup('usagePopup6')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup6">Usage of <span class="code-font"><span class="function-syntax">Errors::fatal_with_file</span></span>:<br/>Text Files - <a href="4-tf.html#SP5_1">&#167;5.1</a>, <a href="4-tf.html#SP5_2">&#167;5.2</a>, <a href="4-tf.html#SP5_3_2">&#167;5.3.2</a><br/>Epub Ebooks - <a href="5-ee.html#SP6_1">&#167;6.1</a>, <a href="5-ee.html#SP6_2">&#167;6.2</a>, <a href="5-ee.html#SP6_3">&#167;6.3</a>, <a href="5-ee.html#SP7_2">&#167;7.2</a>, <a href="5-ee.html#SP7_3">&#167;7.3</a><br/>Binary Files - <a href="6-bf.html#SP7">&#167;7</a>, <a href="6-bf.html#SP8">&#167;8</a>, <a href="6-bf.html#SP9">&#167;9</a><br/>Build Files - <a href="8-bf.html#SP4">&#167;4</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">char</span><span class="plain-syntax"> *</span><span class="identifier-syntax">message</span><span class="plain-syntax">, </span><span class="reserved-syntax">filename</span><span class="plain-syntax"> *</span><span class="identifier-syntax">F</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">TEMPORARY_TEXT</span><span class="plain-syntax">(</span><span class="identifier-syntax">ERM</span><span class="plain-syntax">)</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">WRITE_TO</span><span class="plain-syntax">(</span><span class="identifier-syntax">ERM</span><span class="plain-syntax">, </span><span class="string-syntax">"%s: fatal error: %s: %f\n"</span><span class="plain-syntax">, </span><span class="identifier-syntax">PROGRAM_NAME</span><span class="plain-syntax">, </span><span class="identifier-syntax">message</span><span class="plain-syntax">, </span><span class="identifier-syntax">F</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><a href="3-em.html#SP1" class="function-link"><span class="function-syntax">Errors::issue</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">ERM</span><span class="plain-syntax">, </span><span class="constant-syntax">TRUE</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">DISCARD_TEXT</span><span class="plain-syntax">(</span><span class="identifier-syntax">ERM</span><span class="plain-syntax">)</span>
<span class="plain-syntax">}</span>
<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">Errors::fatal_with_path</span><span class="plain-syntax">(</span><span class="reserved-syntax">char</span><span class="plain-syntax"> *</span><span class="identifier-syntax">message</span><span class="plain-syntax">, </span><span class="reserved-syntax">pathname</span><span class="plain-syntax"> *</span><span class="identifier-syntax">P</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">TEMPORARY_TEXT</span><span class="plain-syntax">(</span><span class="identifier-syntax">ERM</span><span class="plain-syntax">)</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">WRITE_TO</span><span class="plain-syntax">(</span><span class="identifier-syntax">ERM</span><span class="plain-syntax">, </span><span class="string-syntax">"%s: fatal error: %s: %p\n"</span><span class="plain-syntax">, </span><span class="identifier-syntax">PROGRAM_NAME</span><span class="plain-syntax">, </span><span class="identifier-syntax">message</span><span class="plain-syntax">, </span><span class="identifier-syntax">P</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><a href="3-em.html#SP1" class="function-link"><span class="function-syntax">Errors::issue</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">ERM</span><span class="plain-syntax">, </span><span class="constant-syntax">TRUE</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">DISCARD_TEXT</span><span class="plain-syntax">(</span><span class="identifier-syntax">ERM</span><span class="plain-syntax">)</span>
<span class="plain-syntax">}</span>
</pre>
<p class="commentary firstcommentary"><a id="SP3"></a><b>&#167;3. </b>Assertion failures lead to the following:
</p>
<pre class="definitions code-font"><span class="definition-keyword">define</span> <span class="identifier-syntax">internal_error</span><span class="plain-syntax">(</span><span class="identifier-syntax">message</span><span class="plain-syntax">) </span><a href="3-em.html#SP3" class="function-link"><span class="function-syntax">Errors::internal_error_handler</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">NULL</span><span class="plain-syntax">, </span><span class="identifier-syntax">message</span><span class="plain-syntax">, </span><span class="identifier-syntax">__FILE__</span><span class="plain-syntax">, </span><span class="identifier-syntax">__LINE__</span><span class="plain-syntax">)</span>
</pre>
<pre class="displayed-code all-displayed-code code-font">
<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">Errors::internal_error_handler</span><span class="plain-syntax">(</span><span class="reserved-syntax">void</span><span class="plain-syntax"> *</span><span class="identifier-syntax">p</span><span class="plain-syntax">, </span><span class="reserved-syntax">char</span><span class="plain-syntax"> *</span><span class="identifier-syntax">message</span><span class="plain-syntax">, </span><span class="reserved-syntax">char</span><span class="plain-syntax"> *</span><span class="identifier-syntax">f</span><span class="plain-syntax">, </span><span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">lc</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">internal_errors_handler</span><span class="plain-syntax">)</span>
<span class="plain-syntax"> (*</span><span class="identifier-syntax">internal_errors_handler</span><span class="plain-syntax">)(</span><span class="identifier-syntax">p</span><span class="plain-syntax">, </span><span class="identifier-syntax">message</span><span class="plain-syntax">, </span><span class="identifier-syntax">f</span><span class="plain-syntax">, </span><span class="identifier-syntax">lc</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">else</span>
<span class="plain-syntax"> </span><a href="3-em.html#SP2" class="function-link"><span class="function-syntax">Errors::fatal_with_C_string</span></a><span class="plain-syntax">(</span><span class="string-syntax">"internal error (%s)"</span><span class="plain-syntax">, </span><span class="identifier-syntax">message</span><span class="plain-syntax">);</span>
<span class="plain-syntax">}</span>
</pre>
<p class="commentary firstcommentary"><a id="SP4"></a><b>&#167;4. Deliberately crashing. </b>It's sometimes convenient to get a backtrace from the debugger when an error
occurs unexpectedly, and one way to do that is to force a division by zero.
(This is only enabled by <span class="extract"><span class="extract-syntax">-crash</span></span> at the command line and is for debugging only.)
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">debugger_mode</span><span class="plain-syntax"> = </span><span class="constant-syntax">FALSE</span><span class="plain-syntax">;</span>
<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">Errors::enter_debugger_mode</span><button class="popup" onclick="togglePopup('usagePopup7')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup7">Usage of <span class="code-font"><span class="function-syntax">Errors::enter_debugger_mode</span></span>:<br/>Command Line Arguments - <a href="3-cla.html#SP13_1">&#167;13.1</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">void</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">debugger_mode</span><span class="plain-syntax"> = </span><span class="constant-syntax">TRUE</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">printf</span><span class="plain-syntax">(</span><span class="string-syntax">"(Debugger mode enabled: will crash on fatal errors)\n"</span><span class="plain-syntax">);</span>
<span class="plain-syntax">}</span>
<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">Errors::die</span><button class="popup" onclick="togglePopup('usagePopup8')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup8">Usage of <span class="code-font"><span class="function-syntax">Errors::die</span></span>:<br/><a href="3-em.html#SP1">&#167;1</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">void</span><span class="plain-syntax">) { </span><span class="comment-syntax"> as void as it gets</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">DL</span><span class="plain-syntax">) </span><span class="identifier-syntax">STREAM_FLUSH</span><span class="plain-syntax">(</span><span class="identifier-syntax">DL</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">debugger_mode</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">WRITE_TO</span><span class="plain-syntax">(</span><span class="constant-syntax">STDERR</span><span class="plain-syntax">, </span><span class="string-syntax">"(crashing intentionally to allow backtrace)\n"</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">to_deliberately_crash</span><span class="plain-syntax"> = </span><span class="constant-syntax">0</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">printf</span><span class="plain-syntax">(</span><span class="string-syntax">"%d"</span><span class="plain-syntax">, </span><span class="constant-syntax">1</span><span class="plain-syntax">/</span><span class="identifier-syntax">to_deliberately_crash</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> }</span>
<span class="plain-syntax"> </span><span class="comment-syntax"> on a fatal exit, memory isn't freed, because that causes threading problems</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">exit</span><span class="plain-syntax">(2);</span>
<span class="plain-syntax">}</span>
</pre>
<p class="commentary firstcommentary"><a id="SP5"></a><b>&#167;5. Survivable errors. </b>The trick with error messages is to indicate where they occur, and we can
specify this at three levels of abstraction:
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">Errors::nowhere</span><button class="popup" onclick="togglePopup('usagePopup9')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup9">Usage of <span class="code-font"><span class="function-syntax">Errors::nowhere</span></span>:<br/>Epub Ebooks - <a href="5-ee.html#SP7_2_2_3">&#167;7.2.2.3</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">char</span><span class="plain-syntax"> *</span><span class="identifier-syntax">message</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><a href="3-em.html#SP5" class="function-link"><span class="function-syntax">Errors::in_text_file</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">message</span><span class="plain-syntax">, </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">);</span>
<span class="plain-syntax">}</span>
<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">Errors::in_text_file</span><button class="popup" onclick="togglePopup('usagePopup10')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup10">Usage of <span class="code-font"><span class="function-syntax">Errors::in_text_file</span></span>:<br/>Command Line Arguments - <a href="3-cla.html#SP11">&#167;11</a><br/>Build Files - <a href="8-bf.html#SP3">&#167;3</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">char</span><span class="plain-syntax"> *</span><span class="identifier-syntax">message</span><span class="plain-syntax">, </span><span class="reserved-syntax">text_file_position</span><span class="plain-syntax"> *</span><span class="identifier-syntax">here</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">here</span><span class="plain-syntax">)</span>
<span class="plain-syntax"> </span><a href="3-em.html#SP6" class="function-link"><span class="function-syntax">Errors::at_position</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">message</span><span class="plain-syntax">, </span><span class="identifier-syntax">here</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">text_file_filename</span><span class="plain-syntax">, </span><span class="identifier-syntax">here</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">line_count</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">else</span>
<span class="plain-syntax"> </span><a href="3-em.html#SP6" class="function-link"><span class="function-syntax">Errors::at_position</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">message</span><span class="plain-syntax">, </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">, </span><span class="constant-syntax">0</span><span class="plain-syntax">);</span>
<span class="plain-syntax">}</span>
<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">Errors::in_text_file_S</span><button class="popup" onclick="togglePopup('usagePopup11')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup11">Usage of <span class="code-font"><span class="function-syntax">Errors::in_text_file_S</span></span>:<br/>Web Structure - <a href="8-ws.html#SP7_3_2">&#167;7.3.2</a>, <a href="8-ws.html#SP7_3_2_1">&#167;7.3.2.1</a>, <a href="8-ws.html#SP7_3_3_2">&#167;7.3.3.2</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">text_stream</span><span class="plain-syntax"> *</span><span class="identifier-syntax">message</span><span class="plain-syntax">, </span><span class="reserved-syntax">text_file_position</span><span class="plain-syntax"> *</span><span class="identifier-syntax">here</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">here</span><span class="plain-syntax">)</span>
<span class="plain-syntax"> </span><a href="3-em.html#SP6" class="function-link"><span class="function-syntax">Errors::at_position_S</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">message</span><span class="plain-syntax">, </span><span class="identifier-syntax">here</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">text_file_filename</span><span class="plain-syntax">, </span><span class="identifier-syntax">here</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">line_count</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">else</span>
<span class="plain-syntax"> </span><a href="3-em.html#SP6" class="function-link"><span class="function-syntax">Errors::at_position_S</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">message</span><span class="plain-syntax">, </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">, </span><span class="constant-syntax">0</span><span class="plain-syntax">);</span>
<span class="plain-syntax">}</span>
</pre>
<p class="commentary firstcommentary"><a id="SP6"></a><b>&#167;6. </b>Which funnel through:
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">Errors::at_position</span><button class="popup" onclick="togglePopup('usagePopup12')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup12">Usage of <span class="code-font"><span class="function-syntax">Errors::at_position</span></span>:<br/><a href="3-em.html#SP5">&#167;5</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">char</span><span class="plain-syntax"> *</span><span class="identifier-syntax">message</span><span class="plain-syntax">, </span><span class="reserved-syntax">filename</span><span class="plain-syntax"> *</span><span class="identifier-syntax">file</span><span class="plain-syntax">, </span><span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">line</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">TEMPORARY_TEXT</span><span class="plain-syntax">(</span><span class="identifier-syntax">ERM</span><span class="plain-syntax">)</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">WRITE_TO</span><span class="plain-syntax">(</span><span class="identifier-syntax">ERM</span><span class="plain-syntax">, </span><span class="string-syntax">"%s: "</span><span class="plain-syntax">, </span><span class="identifier-syntax">PROGRAM_NAME</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">file</span><span class="plain-syntax">) </span><span class="identifier-syntax">WRITE_TO</span><span class="plain-syntax">(</span><span class="identifier-syntax">ERM</span><span class="plain-syntax">, </span><span class="string-syntax">"%f, line %d: "</span><span class="plain-syntax">, </span><span class="identifier-syntax">file</span><span class="plain-syntax">, </span><span class="identifier-syntax">line</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">WRITE_TO</span><span class="plain-syntax">(</span><span class="identifier-syntax">ERM</span><span class="plain-syntax">, </span><span class="string-syntax">"%s\n"</span><span class="plain-syntax">, </span><span class="identifier-syntax">message</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><a href="3-em.html#SP1" class="function-link"><span class="function-syntax">Errors::issue</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">ERM</span><span class="plain-syntax">, </span><span class="constant-syntax">FALSE</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">DISCARD_TEXT</span><span class="plain-syntax">(</span><span class="identifier-syntax">ERM</span><span class="plain-syntax">)</span>
<span class="plain-syntax">}</span>
<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">Errors::at_position_S</span><button class="popup" onclick="togglePopup('usagePopup13')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup13">Usage of <span class="code-font"><span class="function-syntax">Errors::at_position_S</span></span>:<br/><a href="3-em.html#SP5">&#167;5</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">text_stream</span><span class="plain-syntax"> *</span><span class="identifier-syntax">message</span><span class="plain-syntax">, </span><span class="reserved-syntax">filename</span><span class="plain-syntax"> *</span><span class="identifier-syntax">file</span><span class="plain-syntax">, </span><span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">line</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">TEMPORARY_TEXT</span><span class="plain-syntax">(</span><span class="identifier-syntax">ERM</span><span class="plain-syntax">)</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">WRITE_TO</span><span class="plain-syntax">(</span><span class="identifier-syntax">ERM</span><span class="plain-syntax">, </span><span class="string-syntax">"%s: "</span><span class="plain-syntax">, </span><span class="identifier-syntax">PROGRAM_NAME</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">file</span><span class="plain-syntax">) </span><span class="identifier-syntax">WRITE_TO</span><span class="plain-syntax">(</span><span class="identifier-syntax">ERM</span><span class="plain-syntax">, </span><span class="string-syntax">"%f, line %d: "</span><span class="plain-syntax">, </span><span class="identifier-syntax">file</span><span class="plain-syntax">, </span><span class="identifier-syntax">line</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">WRITE_TO</span><span class="plain-syntax">(</span><span class="identifier-syntax">ERM</span><span class="plain-syntax">, </span><span class="string-syntax">"%S\n"</span><span class="plain-syntax">, </span><span class="identifier-syntax">message</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><a href="3-em.html#SP1" class="function-link"><span class="function-syntax">Errors::issue</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">ERM</span><span class="plain-syntax">, </span><span class="constant-syntax">FALSE</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">DISCARD_TEXT</span><span class="plain-syntax">(</span><span class="identifier-syntax">ERM</span><span class="plain-syntax">)</span>
<span class="plain-syntax">}</span>
</pre>
<p class="commentary firstcommentary"><a id="SP7"></a><b>&#167;7. </b>Lastly:
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">Errors::with_file</span><button class="popup" onclick="togglePopup('usagePopup14')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup14">Usage of <span class="code-font"><span class="function-syntax">Errors::with_file</span></span>:<br/>Text Files - <a href="4-tf.html#SP5_1">&#167;5.1</a>, <a href="4-tf.html#SP5_2">&#167;5.2</a>, <a href="4-tf.html#SP5_3_2">&#167;5.3.2</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">char</span><span class="plain-syntax"> *</span><span class="identifier-syntax">message</span><span class="plain-syntax">, </span><span class="reserved-syntax">filename</span><span class="plain-syntax"> *</span><span class="identifier-syntax">F</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">TEMPORARY_TEXT</span><span class="plain-syntax">(</span><span class="identifier-syntax">ERM</span><span class="plain-syntax">)</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">WRITE_TO</span><span class="plain-syntax">(</span><span class="identifier-syntax">ERM</span><span class="plain-syntax">, </span><span class="string-syntax">"%s: %f: %s\n"</span><span class="plain-syntax">, </span><span class="identifier-syntax">PROGRAM_NAME</span><span class="plain-syntax">, </span><span class="identifier-syntax">F</span><span class="plain-syntax">, </span><span class="identifier-syntax">message</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><a href="3-em.html#SP1" class="function-link"><span class="function-syntax">Errors::issue</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">ERM</span><span class="plain-syntax">, </span><span class="constant-syntax">FALSE</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">DISCARD_TEXT</span><span class="plain-syntax">(</span><span class="identifier-syntax">ERM</span><span class="plain-syntax">)</span>
<span class="plain-syntax">}</span>
<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">Errors::with_text</span><button class="popup" onclick="togglePopup('usagePopup15')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup15">Usage of <span class="code-font"><span class="function-syntax">Errors::with_text</span></span>:<br/>Build Files - <a href="8-bf.html#SP9">&#167;9</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">char</span><span class="plain-syntax"> *</span><span class="identifier-syntax">message</span><span class="plain-syntax">, </span><span class="reserved-syntax">text_stream</span><span class="plain-syntax"> *</span><span class="identifier-syntax">T</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">TEMPORARY_TEXT</span><span class="plain-syntax">(</span><span class="identifier-syntax">ERM</span><span class="plain-syntax">)</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">WRITE_TO</span><span class="plain-syntax">(</span><span class="identifier-syntax">ERM</span><span class="plain-syntax">, </span><span class="string-syntax">"%s: "</span><span class="plain-syntax">, </span><span class="identifier-syntax">PROGRAM_NAME</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">WRITE_TO</span><span class="plain-syntax">(</span><span class="identifier-syntax">ERM</span><span class="plain-syntax">, </span><span class="identifier-syntax">message</span><span class="plain-syntax">, </span><span class="identifier-syntax">T</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">WRITE_TO</span><span class="plain-syntax">(</span><span class="identifier-syntax">ERM</span><span class="plain-syntax">, </span><span class="string-syntax">"\n"</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><a href="3-em.html#SP1" class="function-link"><span class="function-syntax">Errors::issue</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">ERM</span><span class="plain-syntax">, </span><span class="constant-syntax">FALSE</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">DISCARD_TEXT</span><span class="plain-syntax">(</span><span class="identifier-syntax">ERM</span><span class="plain-syntax">)</span>
<span class="plain-syntax">}</span>
</pre>
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