331 lines
35 KiB
HTML
331 lines
35 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
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<html>
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<title>3/cla</title>
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
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<meta http-equiv="Content-Language" content="en-gb">
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<!--Weave of '3/pth' generated by 7-->
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<ul class="crumbs"><li><a href="../webs.html">★</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>Pathnames</b></li></ul><p class="purpose">To manage references to locations in the host computer's file system.</p>
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<ul class="toc"><li><a href="#SP1">§1. About pathnames</a></li><li><a href="#SP2">§2. Home folder</a></li><li><a href="#SP3">§3. Installation folder</a></li><li><a href="#SP4">§4. Creation</a></li><li><a href="#SP5">§5. Text to pathnames</a></li><li><a href="#SP6">§6. Writer</a></li><li><a href="#SP7">§7. Relative pathnames</a></li><li><a href="#SP8">§8. Existence in the file system</a></li></ul><hr class="tocbar">
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<p class="inwebparagraph"><a id="SP1"></a><b>§1. About pathnames. </b>We use the word "pathname" to mean a file-system location of a folder (or
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directory), and "filename" to mean a location of a file. For example:
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</p>
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<p class="inwebparagraph"></p>
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<pre class="display">
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<span class="plain">/Users/rblackmore/Documents/Fireball</span>
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</pre>
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<p class="inwebparagraph">is a pathname, whereas
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</p>
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<p class="inwebparagraph"></p>
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<pre class="display">
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<span class="plain">/Users/rblackmore/Documents/Fireball/whoosh.aiff</span>
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</pre>
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<p class="inwebparagraph">is a filename. All references to folder locations in the filing system will be
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held internally as <code class="display"><span class="extract">pathname</span></code> objects, and all references to file locations as
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<code class="display"><span class="extract">filename</span></code> objects. Once created, these are never destroyed or modified,
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so that it's safe to store a pointer to a pathname or filename anywhere.
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</p>
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<p class="inwebparagraph">Note that a pathname may well be hypothetical, that is, it may well
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describe a folder which doesn't exist on disc.
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</p>
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<p class="inwebparagraph">A full path is a linked list, but reverse-ordered: thus,
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</p>
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<p class="inwebparagraph"></p>
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<pre class="display">
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<span class="plain">/Users/rblackmore/Documents/</span>
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</pre>
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<p class="inwebparagraph">would be represented as a pointer to the <code class="display"><span class="extract">pathname</span></code> for "Documents", which
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in turn points to one for "rblackmore", which in turn points to "/Users".
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Thus the root of the filing system is represented by the null pointer.
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</p>
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<p class="inwebparagraph">Each <code class="display"><span class="extract">pathname</span></code> can represent only a single level in the hierarchy, and
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its textual name is not allowed to contain the <code class="display"><span class="extract">FOLDER_SEPARATOR</span></code> character,
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with just one exception: the <code class="display"><span class="extract">pathname</span></code> at the end of the chain is allowed
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to begin with <code class="display"><span class="extract">FOLDER_SEPARATOR</span></code> to denote that it's at the root of the
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host file system.
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</p>
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<pre class="display">
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<span class="reserved">typedef</span><span class="plain"> </span><span class="reserved">struct</span><span class="plain"> </span><span class="reserved">pathname</span><span class="plain"> {</span>
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<span class="reserved">struct</span><span class="plain"> </span><span class="reserved">text_stream</span><span class="plain"> *</span><span class="identifier">intermediate</span><span class="plain">;</span>
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<span class="reserved">struct</span><span class="plain"> </span><span class="reserved">pathname</span><span class="plain"> *</span><span class="identifier">pathname_of_parent</span><span class="plain">;</span>
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<span class="reserved">int</span><span class="plain"> </span><span class="identifier">known_to_exist</span><span class="plain">; </span> <span class="comment">corresponds to a directory in the filing system</span>
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<span class="constant">MEMORY_MANAGEMENT</span>
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<span class="plain">} </span><span class="reserved">pathname</span><span class="plain">;</span>
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</pre>
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<p class="inwebparagraph"></p>
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<p class="endnote">The structure pathname is accessed in 3/fln and here.</p>
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<p class="inwebparagraph"><a id="SP2"></a><b>§2. Home folder. </b>We get the path to the user's home folder from the environment variable
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<code class="display"><span class="extract">HOME</span></code>, if it exists.
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</p>
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<pre class="display">
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<span class="reserved">pathname</span><span class="plain"> *</span><span class="identifier">home_path</span><span class="plain"> = </span><span class="identifier">NULL</span><span class="plain">;</span>
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<span class="reserved">void</span><span class="plain"> </span><span class="functiontext">Pathnames::start</span><span class="plain">(</span><span class="reserved">void</span><span class="plain">) {</span>
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<span class="reserved">char</span><span class="plain"> *</span><span class="identifier">home</span><span class="plain"> = (</span><span class="reserved">char</span><span class="plain"> *) (</span><span class="functiontext">Platform::getenv</span><span class="plain">(</span><span class="string">"HOME"</span><span class="plain">));</span>
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<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">home</span><span class="plain">) {</span>
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<span class="reserved">text_stream</span><span class="plain"> *</span><span class="identifier">H</span><span class="plain"> = </span><span class="functiontext">Str::new_from_locale_string</span><span class="plain">(</span><span class="identifier">home</span><span class="plain">);</span>
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<span class="identifier">home_path</span><span class="plain"> = </span><span class="functiontext">Pathnames::from_text</span><span class="plain">(</span><span class="identifier">H</span><span class="plain">);</span>
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<span class="identifier">home_path</span><span class="plain">-</span><span class="element">>known_to_exist</span><span class="plain"> = </span><span class="constant">TRUE</span><span class="plain">;</span>
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<span class="plain">}</span>
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<span class="plain">}</span>
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</pre>
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<p class="inwebparagraph"></p>
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<p class="endnote">The function Pathnames::start appears nowhere else.</p>
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<p class="inwebparagraph"><a id="SP3"></a><b>§3. Installation folder. </b></p>
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<pre class="display">
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<span class="reserved">pathname</span><span class="plain"> *</span><span class="identifier">installation_path</span><span class="plain"> = </span><span class="identifier">NULL</span><span class="plain">;</span>
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<span class="reserved">void</span><span class="plain"> </span><span class="functiontext">Pathnames::set_installation_path</span><span class="plain">(</span><span class="reserved">pathname</span><span class="plain"> *</span><span class="identifier">P</span><span class="plain">) {</span>
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<span class="identifier">installation_path</span><span class="plain"> = </span><span class="identifier">P</span><span class="plain">;</span>
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<span class="plain">}</span>
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<span class="reserved">pathname</span><span class="plain"> *</span><span class="functiontext">Pathnames::installation_path</span><span class="plain">(</span><span class="reserved">const</span><span class="plain"> </span><span class="reserved">char</span><span class="plain"> *</span><span class="identifier">V</span><span class="plain">, </span><span class="reserved">text_stream</span><span class="plain"> *</span><span class="identifier">def</span><span class="plain">) {</span>
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<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">installation_path</span><span class="plain">) </span><span class="reserved">return</span><span class="plain"> </span><span class="identifier">installation_path</span><span class="plain">;</span>
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<span class="identifier">wchar_t</span><span class="plain"> </span><span class="identifier">where</span><span class="plain">[4*</span><span class="constant">MAX_FILENAME_LENGTH</span><span class="plain">];</span>
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<span class="identifier">where</span><span class="plain">[0] = 0;</span>
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<span class="functiontext">Platform::where_am_i</span><span class="plain">(</span><span class="identifier">where</span><span class="plain">, 4*</span><span class="constant">MAX_FILENAME_LENGTH</span><span class="plain">);</span>
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<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">where</span><span class="plain">[0]) {</span>
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<span class="reserved">text_stream</span><span class="plain"> *</span><span class="identifier">v</span><span class="plain"> = </span><span class="functiontext">Str::new_from_wide_string</span><span class="plain">(</span><span class="identifier">where</span><span class="plain">);</span>
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<span class="reserved">filename</span><span class="plain"> *</span><span class="identifier">F</span><span class="plain"> = </span><span class="functiontext">Filenames::from_text</span><span class="plain">(</span><span class="identifier">v</span><span class="plain">);</span>
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<span class="reserved">pathname</span><span class="plain"> *</span><span class="identifier">P</span><span class="plain"> = </span><span class="functiontext">Filenames::get_path_to</span><span class="plain">(</span><span class="identifier">F</span><span class="plain">);</span>
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<span class="reserved">if</span><span class="plain"> ((</span><span class="identifier">P</span><span class="plain">) && (</span><span class="functiontext">Str::eq</span><span class="plain">(</span><span class="identifier">P</span><span class="plain">-</span><span class="element">>intermediate</span><span class="plain">, </span><span class="identifier">I</span><span class="string">"Tangled"</span><span class="plain">)))</span>
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<span class="identifier">P</span><span class="plain"> = </span><span class="identifier">P</span><span class="plain">-</span><span class="element">>pathname_of_parent</span><span class="plain">;</span>
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<span class="reserved">return</span><span class="plain"> </span><span class="identifier">P</span><span class="plain">;</span>
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<span class="plain">}</span>
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<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">V</span><span class="plain">) {</span>
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<span class="reserved">char</span><span class="plain"> *</span><span class="identifier">val</span><span class="plain"> = </span><span class="functiontext">Platform::getenv</span><span class="plain">(</span><span class="identifier">V</span><span class="plain">);</span>
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<span class="reserved">if</span><span class="plain"> ((</span><span class="identifier">val</span><span class="plain">) && (</span><span class="identifier">val</span><span class="plain">[0])) {</span>
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<span class="reserved">text_stream</span><span class="plain"> *</span><span class="identifier">v</span><span class="plain"> = </span><span class="functiontext">Str::new_from_locale_string</span><span class="plain">(</span><span class="identifier">val</span><span class="plain">);</span>
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<span class="reserved">return</span><span class="plain"> </span><span class="functiontext">Pathnames::from_text</span><span class="plain">(</span><span class="identifier">v</span><span class="plain">);</span>
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<span class="plain">}</span>
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<span class="plain">}</span>
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<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">def</span><span class="plain">) </span><span class="reserved">return</span><span class="plain"> </span><span class="functiontext">Pathnames::from_text</span><span class="plain">(</span><span class="identifier">def</span><span class="plain">);</span>
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<span class="reserved">return</span><span class="plain"> </span><span class="identifier">NULL</span><span class="plain">;</span>
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<span class="plain">}</span>
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</pre>
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<p class="inwebparagraph"></p>
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<p class="endnote">The function Pathnames::set_installation_path is used in 3/cla (<a href="3-cla.html#SP8_1">§8.1</a>).</p>
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<p class="endnote">The function Pathnames::installation_path appears nowhere else.</p>
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<p class="inwebparagraph"><a id="SP4"></a><b>§4. Creation. </b>A subfolder is made by taking an existing pathname (or possible <code class="display"><span class="extract">NULL</span></code>) and
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then going one level deeper, using the supplied name.
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</p>
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<pre class="display">
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<span class="reserved">pathname</span><span class="plain"> *</span><span class="functiontext">Pathnames::subfolder</span><span class="plain">(</span><span class="reserved">pathname</span><span class="plain"> *</span><span class="identifier">P</span><span class="plain">, </span><span class="reserved">text_stream</span><span class="plain"> *</span><span class="identifier">folder_name</span><span class="plain">) {</span>
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<span class="reserved">return</span><span class="plain"> </span><span class="functiontext">Pathnames::primitive</span><span class="plain">(</span><span class="identifier">folder_name</span><span class="plain">, 0, </span><span class="functiontext">Str::len</span><span class="plain">(</span><span class="identifier">folder_name</span><span class="plain">), </span><span class="identifier">P</span><span class="plain">);</span>
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<span class="plain">}</span>
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<span class="reserved">pathname</span><span class="plain"> *</span><span class="functiontext">Pathnames::primitive</span><span class="plain">(</span><span class="reserved">text_stream</span><span class="plain"> *</span><span class="identifier">str</span><span class="plain">, </span><span class="reserved">int</span><span class="plain"> </span><span class="identifier">from</span><span class="plain">, </span><span class="reserved">int</span><span class="plain"> </span><span class="identifier">to</span><span class="plain">, </span><span class="reserved">pathname</span><span class="plain"> *</span><span class="identifier">par</span><span class="plain">) {</span>
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<span class="reserved">pathname</span><span class="plain"> *</span><span class="identifier">P</span><span class="plain"> = </span><span class="identifier">CREATE</span><span class="plain">(</span><span class="reserved">pathname</span><span class="plain">);</span>
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<span class="identifier">P</span><span class="plain">-</span><span class="element">>pathname_of_parent</span><span class="plain"> = </span><span class="identifier">par</span><span class="plain">;</span>
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<span class="identifier">P</span><span class="plain">-</span><span class="element">>known_to_exist</span><span class="plain"> = </span><span class="constant">FALSE</span><span class="plain">;</span>
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<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">to</span><span class="plain">-</span><span class="identifier">from</span><span class="plain"> <= 0) </span><span class="identifier">internal_error</span><span class="plain">(</span><span class="string">"empty intermediate pathname"</span><span class="plain">);</span>
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<span class="identifier">P</span><span class="plain">-</span><span class="element">>intermediate</span><span class="plain"> = </span><span class="functiontext">Str::new_with_capacity</span><span class="plain">(</span><span class="identifier">to</span><span class="plain">-</span><span class="identifier">from</span><span class="plain">+1);</span>
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<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">str</span><span class="plain">)</span>
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<span class="reserved">for</span><span class="plain"> (</span><span class="reserved">int</span><span class="plain"> </span><span class="identifier">i</span><span class="plain"> = </span><span class="identifier">from</span><span class="plain">; </span><span class="identifier">i</span><span class="plain"> < </span><span class="identifier">to</span><span class="plain">; </span><span class="identifier">i</span><span class="plain">++)</span>
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<span class="identifier">PUT_TO</span><span class="plain">(</span><span class="identifier">P</span><span class="plain">-</span><span class="element">>intermediate</span><span class="plain">, </span><span class="functiontext">Str::get</span><span class="plain">(</span><span class="functiontext">Str::at</span><span class="plain">(</span><span class="identifier">str</span><span class="plain">, </span><span class="identifier">i</span><span class="plain">)));</span>
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<span class="reserved">return</span><span class="plain"> </span><span class="identifier">P</span><span class="plain">;</span>
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<span class="plain">}</span>
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</pre>
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<p class="inwebparagraph"></p>
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<p class="endnote">The function Pathnames::subfolder is used in 5/ee (<a href="5-ee.html#SP6">§6</a>, <a href="5-ee.html#SP6_2">§6.2</a>).</p>
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<p class="endnote">The function Pathnames::primitive is used in <a href="#SP5">§5</a>.</p>
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<p class="inwebparagraph"><a id="SP5"></a><b>§5. Text to pathnames. </b>The following takes a text of a name and returns a pathname,
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possibly relative to the home folder. Empty folder names are ignored
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except possibly for an initial slash, so for example <code class="display"><span class="extract">paris/roubaix</span></code>,
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<code class="display"><span class="extract">paris//roubaix</span></code> and <code class="display"><span class="extract">paris/roubaix/</span></code> are indistinguishable here, but
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<code class="display"><span class="extract">/paris/roubaix</span></code> is different.
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</p>
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<pre class="display">
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<span class="reserved">pathname</span><span class="plain"> *</span><span class="functiontext">Pathnames::from_text</span><span class="plain">(</span><span class="reserved">text_stream</span><span class="plain"> *</span><span class="identifier">path</span><span class="plain">) {</span>
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<span class="reserved">return</span><span class="plain"> </span><span class="functiontext">Pathnames::from_text_relative</span><span class="plain">(</span><span class="identifier">NULL</span><span class="plain">, </span><span class="identifier">path</span><span class="plain">);</span>
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<span class="plain">}</span>
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<span class="reserved">pathname</span><span class="plain"> *</span><span class="functiontext">Pathnames::from_text_relative</span><span class="plain">(</span><span class="reserved">pathname</span><span class="plain"> *</span><span class="identifier">P</span><span class="plain">, </span><span class="reserved">text_stream</span><span class="plain"> *</span><span class="identifier">path</span><span class="plain">) {</span>
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<span class="reserved">pathname</span><span class="plain"> *</span><span class="identifier">at</span><span class="plain"> = </span><span class="identifier">P</span><span class="plain">;</span>
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<span class="reserved">int</span><span class="plain"> </span><span class="identifier">i</span><span class="plain"> = 0, </span><span class="identifier">pos</span><span class="plain"> = 0;</span>
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<span class="reserved">if</span><span class="plain"> ((</span><span class="functiontext">Str::get</span><span class="plain">(</span><span class="functiontext">Str::start</span><span class="plain">(</span><span class="identifier">path</span><span class="plain">))) && (</span><span class="identifier">P</span><span class="plain"> == </span><span class="identifier">NULL</span><span class="plain">)) </span><span class="identifier">i</span><span class="plain">++;</span>
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<span class="reserved">for</span><span class="plain"> (; </span><span class="identifier">i</span><span class="plain"> < </span><span class="functiontext">Str::len</span><span class="plain">(</span><span class="identifier">path</span><span class="plain">); </span><span class="identifier">i</span><span class="plain">++)</span>
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<span class="reserved">if</span><span class="plain"> (</span><span class="functiontext">Str::get</span><span class="plain">(</span><span class="functiontext">Str::at</span><span class="plain">(</span><span class="identifier">path</span><span class="plain">, </span><span class="identifier">i</span><span class="plain">)) == </span><span class="constant">FOLDER_SEPARATOR</span><span class="plain">) {</span>
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<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">i</span><span class="plain"> > </span><span class="identifier">pos</span><span class="plain">) </span><span class="identifier">at</span><span class="plain"> = </span><span class="functiontext">Pathnames::primitive</span><span class="plain">(</span><span class="identifier">path</span><span class="plain">, </span><span class="identifier">pos</span><span class="plain">, </span><span class="identifier">i</span><span class="plain">, </span><span class="identifier">at</span><span class="plain">);</span>
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<span class="identifier">pos</span><span class="plain"> = </span><span class="identifier">i</span><span class="plain">+1;</span>
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<span class="plain">}</span>
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<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">i</span><span class="plain"> > </span><span class="identifier">pos</span><span class="plain">) </span><span class="identifier">at</span><span class="plain"> = </span><span class="functiontext">Pathnames::primitive</span><span class="plain">(</span><span class="identifier">path</span><span class="plain">, </span><span class="identifier">pos</span><span class="plain">, </span><span class="identifier">i</span><span class="plain">, </span><span class="identifier">at</span><span class="plain">);</span>
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<span class="reserved">return</span><span class="plain"> </span><span class="identifier">at</span><span class="plain">;</span>
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<span class="plain">}</span>
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</pre>
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<p class="inwebparagraph"></p>
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<p class="endnote">The function Pathnames::from_text is used in <a href="#SP2">§2</a>, <a href="#SP3">§3</a>, 3/cla (<a href="3-cla.html#SP8_1">§8.1</a>, <a href="3-cla.html#SP8_1_1">§8.1.1</a>), 3/fln (<a href="3-fln.html#SP3">§3</a>), 5/ee (<a href="5-ee.html#SP7_4">§7.4</a>).</p>
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<p class="endnote">The function Pathnames::from_text_relative appears nowhere else.</p>
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<p class="inwebparagraph"><a id="SP6"></a><b>§6. Writer. </b>Conversely, by the miracle of depth-first recursion:
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</p>
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<pre class="display">
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<span class="reserved">void</span><span class="plain"> </span><span class="functiontext">Pathnames::writer</span><span class="plain">(</span><span class="constant">OUTPUT_STREAM</span><span class="plain">, </span><span class="reserved">char</span><span class="plain"> *</span><span class="identifier">format_string</span><span class="plain">, </span><span class="reserved">void</span><span class="plain"> *</span><span class="identifier">vP</span><span class="plain">) {</span>
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<span class="reserved">pathname</span><span class="plain"> *</span><span class="identifier">P</span><span class="plain"> = (</span><span class="reserved">pathname</span><span class="plain"> *) </span><span class="identifier">vP</span><span class="plain">;</span>
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<span class="reserved">int</span><span class="plain"> </span><span class="identifier">divider</span><span class="plain"> = </span><span class="constant">FOLDER_SEPARATOR</span><span class="plain">;</span>
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<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">format_string</span><span class="plain">[0] == </span><span class="character">'/'</span><span class="plain">) </span><span class="identifier">divider</span><span class="plain"> = </span><span class="character">'/'</span><span class="plain">;</span>
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<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">P</span><span class="plain">) </span><span class="functiontext">Pathnames::writer_r</span><span class="plain">(</span><span class="identifier">OUT</span><span class="plain">, </span><span class="identifier">P</span><span class="plain">, </span><span class="identifier">divider</span><span class="plain">); </span><span class="reserved">else</span><span class="plain"> </span><span class="identifier">WRITE</span><span class="plain">(</span><span class="string">"."</span><span class="plain">);</span>
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<span class="plain">}</span>
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<span class="reserved">void</span><span class="plain"> </span><span class="functiontext">Pathnames::writer_r</span><span class="plain">(</span><span class="constant">OUTPUT_STREAM</span><span class="plain">, </span><span class="reserved">pathname</span><span class="plain"> *</span><span class="identifier">P</span><span class="plain">, </span><span class="reserved">int</span><span class="plain"> </span><span class="identifier">divider</span><span class="plain">) {</span>
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<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">P</span><span class="plain">-</span><span class="element">>pathname_of_parent</span><span class="plain">) {</span>
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<span class="functiontext">Pathnames::writer_r</span><span class="plain">(</span><span class="identifier">OUT</span><span class="plain">, </span><span class="identifier">P</span><span class="plain">-</span><span class="element">>pathname_of_parent</span><span class="plain">, </span><span class="identifier">divider</span><span class="plain">);</span>
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<span class="identifier">PUT</span><span class="plain">(</span><span class="identifier">divider</span><span class="plain">);</span>
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<span class="plain">}</span>
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<span class="identifier">WRITE</span><span class="plain">(</span><span class="string">"%S"</span><span class="plain">, </span><span class="identifier">P</span><span class="plain">-</span><span class="element">>intermediate</span><span class="plain">);</span>
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<span class="plain">}</span>
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</pre>
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<p class="inwebparagraph"></p>
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<p class="endnote">The function Pathnames::writer is used in 1/fnd (<a href="1-fnd.html#SP8_1">§8.1</a>), 3/fln (<a href="3-fln.html#SP4">§4</a>).</p>
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<p class="endnote">The function Pathnames::writer_r appears nowhere else.</p>
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<p class="inwebparagraph"><a id="SP7"></a><b>§7. Relative pathnames. </b>Occasionally we want to shorten a pathname relative to another one:
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for example,
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</p>
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<p class="inwebparagraph"></p>
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<pre class="display">
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<span class="plain">/Users/rblackmore/Documents/Fireball/tablature</span>
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</pre>
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<p class="inwebparagraph">relative to
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</p>
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<p class="inwebparagraph"></p>
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<pre class="display">
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<span class="plain">/Users/rblackmore/Documents/</span>
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</pre>
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<p class="inwebparagraph">would be
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</p>
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<p class="inwebparagraph"></p>
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<pre class="display">
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<span class="plain">Fireball/tablature</span>
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</pre>
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<p class="inwebparagraph">Note that this does not correctly handle symlinks, <code class="display"><span class="extract">.</span></code>, <code class="display"><span class="extract">..</span></code> and so on,
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so it's probably not wise to use it with filenames typed in at the command
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line.
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</p>
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<pre class="display">
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<span class="reserved">void</span><span class="plain"> </span><span class="functiontext">Pathnames::to_text_relative</span><span class="plain">(</span><span class="constant">OUTPUT_STREAM</span><span class="plain">, </span><span class="reserved">pathname</span><span class="plain"> *</span><span class="identifier">P</span><span class="plain">, </span><span class="reserved">pathname</span><span class="plain"> *</span><span class="identifier">R</span><span class="plain">) {</span>
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<span class="identifier">TEMPORARY_TEXT</span><span class="plain">(</span><span class="identifier">rt</span><span class="plain">);</span>
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<span class="identifier">TEMPORARY_TEXT</span><span class="plain">(</span><span class="identifier">pt</span><span class="plain">);</span>
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<span class="identifier">WRITE_TO</span><span class="plain">(</span><span class="identifier">rt</span><span class="plain">, </span><span class="string">"%p"</span><span class="plain">, </span><span class="identifier">R</span><span class="plain">);</span>
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<span class="identifier">WRITE_TO</span><span class="plain">(</span><span class="identifier">pt</span><span class="plain">, </span><span class="string">"%p"</span><span class="plain">, </span><span class="identifier">P</span><span class="plain">);</span>
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<span class="reserved">int</span><span class="plain"> </span><span class="identifier">n</span><span class="plain"> = </span><span class="functiontext">Str::len</span><span class="plain">(</span><span class="identifier">pt</span><span class="plain">);</span>
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<span class="reserved">if</span><span class="plain"> ((</span><span class="functiontext">Str::prefix_eq</span><span class="plain">(</span><span class="identifier">rt</span><span class="plain">, </span><span class="identifier">pt</span><span class="plain">, </span><span class="identifier">n</span><span class="plain">)) && (</span><span class="functiontext">Str::get_at</span><span class="plain">(</span><span class="identifier">rt</span><span class="plain">, </span><span class="identifier">n</span><span class="plain">)==</span><span class="constant">FOLDER_SEPARATOR</span><span class="plain">)) {</span>
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<span class="functiontext">Str::delete_n_characters</span><span class="plain">(</span><span class="identifier">rt</span><span class="plain">, </span><span class="identifier">n</span><span class="plain">+1);</span>
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<span class="identifier">WRITE</span><span class="plain">(</span><span class="string">"%S"</span><span class="plain">, </span><span class="identifier">rt</span><span class="plain">);</span>
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|
<span class="plain">} </span><span class="reserved">else</span><span class="plain"> </span><span class="identifier">internal_error</span><span class="plain">(</span><span class="string">"pathname not relative to pathname"</span><span class="plain">);</span>
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|
<span class="identifier">DISCARD_TEXT</span><span class="plain">(</span><span class="identifier">rt</span><span class="plain">);</span>
|
|
<span class="identifier">DISCARD_TEXT</span><span class="plain">(</span><span class="identifier">pt</span><span class="plain">);</span>
|
|
<span class="plain">}</span>
|
|
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|
<span class="reserved">pathname</span><span class="plain"> *</span><span class="functiontext">Pathnames::up</span><span class="plain">(</span><span class="reserved">pathname</span><span class="plain"> *</span><span class="identifier">P</span><span class="plain">) {</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">P</span><span class="plain"> == </span><span class="identifier">NULL</span><span class="plain">) </span><span class="identifier">internal_error</span><span class="plain">(</span><span class="string">"can't go up from root directory"</span><span class="plain">);</span>
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|
<span class="reserved">return</span><span class="plain"> </span><span class="identifier">P</span><span class="plain">-</span><span class="element">>pathname_of_parent</span><span class="plain">;</span>
|
|
<span class="plain">}</span>
|
|
|
|
<span class="reserved">text_stream</span><span class="plain"> *</span><span class="functiontext">Pathnames::directory_name</span><span class="plain">(</span><span class="reserved">pathname</span><span class="plain"> *</span><span class="identifier">P</span><span class="plain">) {</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">P</span><span class="plain"> == </span><span class="identifier">NULL</span><span class="plain">) </span><span class="reserved">return</span><span class="plain"> </span><span class="identifier">NULL</span><span class="plain">;</span>
|
|
<span class="reserved">return</span><span class="plain"> </span><span class="identifier">P</span><span class="plain">-</span><span class="element">>intermediate</span><span class="plain">;</span>
|
|
<span class="plain">}</span>
|
|
</pre>
|
|
|
|
<p class="inwebparagraph"></p>
|
|
|
|
<p class="endnote">The function Pathnames::to_text_relative appears nowhere else.</p>
|
|
|
|
<p class="endnote">The function Pathnames::up appears nowhere else.</p>
|
|
|
|
<p class="endnote">The function Pathnames::directory_name appears nowhere else.</p>
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<p class="inwebparagraph"><a id="SP8"></a><b>§8. Existence in the file system. </b>Just because we have a pathname, it doesn't follow that any folder exists
|
|
on the file system with that path.
|
|
</p>
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|
|
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|
<pre class="display">
|
|
<span class="reserved">int</span><span class="plain"> </span><span class="functiontext">Pathnames::create_in_file_system</span><span class="plain">(</span><span class="reserved">pathname</span><span class="plain"> *</span><span class="identifier">P</span><span class="plain">) {</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">P</span><span class="plain"> == </span><span class="identifier">NULL</span><span class="plain">) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">TRUE</span><span class="plain">; </span> <span class="comment">the root of the file system always exists</span>
|
|
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">P</span><span class="plain">-</span><span class="element">>known_to_exist</span><span class="plain">) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">TRUE</span><span class="plain">;</span>
|
|
<span class="reserved">char</span><span class="plain"> </span><span class="identifier">transcoded_pathname</span><span class="plain">[4*</span><span class="constant">MAX_FILENAME_LENGTH</span><span class="plain">];</span>
|
|
<span class="identifier">TEMPORARY_TEXT</span><span class="plain">(</span><span class="identifier">pn</span><span class="plain">);</span>
|
|
<span class="identifier">WRITE_TO</span><span class="plain">(</span><span class="identifier">pn</span><span class="plain">, </span><span class="string">"%p"</span><span class="plain">, </span><span class="identifier">P</span><span class="plain">);</span>
|
|
<span class="functiontext">Str::copy_to_locale_string</span><span class="plain">(</span><span class="identifier">transcoded_pathname</span><span class="plain">, </span><span class="identifier">pn</span><span class="plain">, 4*</span><span class="constant">MAX_FILENAME_LENGTH</span><span class="plain">);</span>
|
|
<span class="identifier">DISCARD_TEXT</span><span class="plain">(</span><span class="identifier">pn</span><span class="plain">);</span>
|
|
<span class="identifier">P</span><span class="plain">-</span><span class="element">>known_to_exist</span><span class="plain"> = </span><span class="functiontext">Platform::mkdir</span><span class="plain">(</span><span class="identifier">transcoded_pathname</span><span class="plain">);</span>
|
|
<span class="reserved">return</span><span class="plain"> </span><span class="identifier">P</span><span class="plain">-</span><span class="element">>known_to_exist</span><span class="plain">;</span>
|
|
<span class="plain">}</span>
|
|
</pre>
|
|
|
|
<p class="inwebparagraph"></p>
|
|
|
|
<p class="endnote">The function Pathnames::create_in_file_system is used in 5/ee (<a href="5-ee.html#SP6">§6</a>, <a href="5-ee.html#SP6_2">§6.2</a>).</p>
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<hr class="tocbar">
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<ul class="toc"><li><a href="3-cla.html">Back to 'Command Line Arguments'</a></li><li><a href="3-fln.html">Continue with 'Filenames'</a></li></ul><hr class="tocbar">
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