148 lines
15 KiB
HTML
148 lines
15 KiB
HTML
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<title>std::filesystem::perm_options</title>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_filesystem_perm_options skin-cppreference2 action-view cpp-navbar">
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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::filesystem::</span>perm_options</h1>
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<div id="bodyContent">
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<div id="contentSub"><span class="subpages">< <a href="cpp.html">cpp</a>‎ | <a href="cpp-filesystem.html">filesystem</a></span></div>
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<td>
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<div>定义于头文件 <code><a href="cpp-header-filesystem.html"><filesystem></a></code></div>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw2">enum</span> <span class="kw1">class</span> perm_options <span class="br0">{</span><br /></span>
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<p> replace <span class="sy1">=</span> <span class="coMULTI">/* unspecified */</span>,<br />
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add <span class="sy1">=</span> <span class="coMULTI">/* unspecified */</span>,<br />
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remove <span class="sy1">=</span> <span class="coMULTI">/* unspecified */</span>,<br />
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nofollow <span class="sy1">=</span> <span class="coMULTI">/* unspecified */</span><br /></p>
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<span class="br0">}</span><span class="sy4">;</span></div>
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</td>
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<td class="t-dcl-nopad"></td>
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<td><span class="t-mark-rev t-since-cxx17">(C++17 起)</span></td>
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<tr class="t-dcl-sep">
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<td></td>
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<p>此类型代表控制函数 <a href="cpp-filesystem-permissions.html"><tt>permissions()</tt></a> 行为的可用选项。</p>
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<p><code>perm_options</code> 满足满足<a href="cpp-named_req-BitmaskType.html"><span style="font-style:italic">位掩码类型</span> <span style="font-family: Georgia, 'DejaVu Serif', serif; font-style:italic">(BitmaskType)</span></a> 的要求（表示位运算符 <span class="t-c"><span class="mw-geshi cpp source-cpp">operator<span class="sy3">&</span></span></span> 、 <span class="t-c"><span class="mw-geshi cpp source-cpp">operator<span class="sy3">|</span></span></span> 、 <span class="t-c"><span class="mw-geshi cpp source-cpp">operator<span class="sy3">^</span></span></span> 、 <span class="t-c"><span class="mw-geshi cpp source-cpp">operator~</span></span> 、 <span class="t-c"><span class="mw-geshi cpp source-cpp">operator<span class="sy3">&</span><span class="sy1">=</span></span></span> 、 <span class="t-c"><span class="mw-geshi cpp source-cpp">operator<span class="sy3">|</span><span class="sy1">=</span></span></span> 及 <span class="t-c"><span class="mw-geshi cpp source-cpp">operator<span class="sy3">^</span><span class="sy1">=</span></span></span> 对此类型定义）</p>
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<h3><span class="mw-headline" id=".E6.88.90.E5.91.98.E5.B8.B8.E9.87.8F">成员常量</span></h3>
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<p><code>add</code> 、 <code>remove</code> 、 <code>replace</code> 至多可以存在一个，否则 permissions 函数的行为未定义。</p>
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<table class="wikitable" style="text-align:left; font-size:85%; max-width:90em;">
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<th>成员常量</th>
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<th>含义</th>
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<td><code>replace</code></td>
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<td>以给 <code>permissions()</code> 的参数完全替换权限（默认行为）</td>
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<td><code>add</code></td>
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<td>以当前权限和参数的逐位或替换权限</td>
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<td><code>remove</code></td>
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<td>以当前权限和参数取反结果的逐位与替换权限</td>
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<td><code>nofollow</code></td>
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<td>permissions 将更改符号链接自身，而非其所代表的文件</td>
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</tr>
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</table>
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<h3><span class="mw-headline" id=".E7.A4.BA.E4.BE.8B">示例</span></h3>
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<div class="t-example">
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<div class="t-example-live-link"></div>
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<div dir="ltr" class="mw-geshi" style="text-align: left;">
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<div class="cpp source-cpp">
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<pre class="de1"><span class="co2">#include <fstream></span>
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<span class="co2">#include <bitset></span>
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<span class="co2">#include <iostream></span>
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<span class="co2">#include <filesystem></span>
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<span class="kw1">namespace</span> fs <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">filesystem</span><span class="sy4">;</span>
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<span class="kw4">void</span> demo_perms<span class="br0">(</span>fs<span class="sy4">::</span><span class="me2">perms</span> p<span class="br0">)</span>
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<span class="br0">{</span>
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<a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> <span class="br0">(</span><span class="br0">(</span>p <span class="sy3">&</span> fs<span class="sy4">::</span><span class="me2">perms</span><span class="sy4">::</span><span class="me2">owner_read</span><span class="br0">)</span> <span class="sy3">!</span><span class="sy1">=</span> fs<span class="sy4">::</span><span class="me2">perms</span><span class="sy4">::</span><span class="me2">none</span> <span class="sy4">?</span> <span class="st0">"r"</span> <span class="sy4">:</span> <span class="st0">"-"</span><span class="br0">)</span>
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<span class="sy1"><<</span> <span class="br0">(</span><span class="br0">(</span>p <span class="sy3">&</span> fs<span class="sy4">::</span><span class="me2">perms</span><span class="sy4">::</span><span class="me2">owner_write</span><span class="br0">)</span> <span class="sy3">!</span><span class="sy1">=</span> fs<span class="sy4">::</span><span class="me2">perms</span><span class="sy4">::</span><span class="me2">none</span> <span class="sy4">?</span> <span class="st0">"w"</span> <span class="sy4">:</span> <span class="st0">"-"</span><span class="br0">)</span>
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<span class="sy1"><<</span> <span class="br0">(</span><span class="br0">(</span>p <span class="sy3">&</span> fs<span class="sy4">::</span><span class="me2">perms</span><span class="sy4">::</span><span class="me2">owner_exec</span><span class="br0">)</span> <span class="sy3">!</span><span class="sy1">=</span> fs<span class="sy4">::</span><span class="me2">perms</span><span class="sy4">::</span><span class="me2">none</span> <span class="sy4">?</span> <span class="st0">"x"</span> <span class="sy4">:</span> <span class="st0">"-"</span><span class="br0">)</span>
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<span class="sy1"><<</span> <span class="br0">(</span><span class="br0">(</span>p <span class="sy3">&</span> fs<span class="sy4">::</span><span class="me2">perms</span><span class="sy4">::</span><span class="me2">group_read</span><span class="br0">)</span> <span class="sy3">!</span><span class="sy1">=</span> fs<span class="sy4">::</span><span class="me2">perms</span><span class="sy4">::</span><span class="me2">none</span> <span class="sy4">?</span> <span class="st0">"r"</span> <span class="sy4">:</span> <span class="st0">"-"</span><span class="br0">)</span>
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<span class="sy1"><<</span> <span class="br0">(</span><span class="br0">(</span>p <span class="sy3">&</span> fs<span class="sy4">::</span><span class="me2">perms</span><span class="sy4">::</span><span class="me2">group_write</span><span class="br0">)</span> <span class="sy3">!</span><span class="sy1">=</span> fs<span class="sy4">::</span><span class="me2">perms</span><span class="sy4">::</span><span class="me2">none</span> <span class="sy4">?</span> <span class="st0">"w"</span> <span class="sy4">:</span> <span class="st0">"-"</span><span class="br0">)</span>
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<span class="sy1"><<</span> <span class="br0">(</span><span class="br0">(</span>p <span class="sy3">&</span> fs<span class="sy4">::</span><span class="me2">perms</span><span class="sy4">::</span><span class="me2">group_exec</span><span class="br0">)</span> <span class="sy3">!</span><span class="sy1">=</span> fs<span class="sy4">::</span><span class="me2">perms</span><span class="sy4">::</span><span class="me2">none</span> <span class="sy4">?</span> <span class="st0">"x"</span> <span class="sy4">:</span> <span class="st0">"-"</span><span class="br0">)</span>
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<span class="sy1"><<</span> <span class="br0">(</span><span class="br0">(</span>p <span class="sy3">&</span> fs<span class="sy4">::</span><span class="me2">perms</span><span class="sy4">::</span><span class="me2">others_read</span><span class="br0">)</span> <span class="sy3">!</span><span class="sy1">=</span> fs<span class="sy4">::</span><span class="me2">perms</span><span class="sy4">::</span><span class="me2">none</span> <span class="sy4">?</span> <span class="st0">"r"</span> <span class="sy4">:</span> <span class="st0">"-"</span><span class="br0">)</span>
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<span class="sy1"><<</span> <span class="br0">(</span><span class="br0">(</span>p <span class="sy3">&</span> fs<span class="sy4">::</span><span class="me2">perms</span><span class="sy4">::</span><span class="me2">others_write</span><span class="br0">)</span> <span class="sy3">!</span><span class="sy1">=</span> fs<span class="sy4">::</span><span class="me2">perms</span><span class="sy4">::</span><span class="me2">none</span> <span class="sy4">?</span> <span class="st0">"w"</span> <span class="sy4">:</span> <span class="st0">"-"</span><span class="br0">)</span>
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<span class="sy1"><<</span> <span class="br0">(</span><span class="br0">(</span>p <span class="sy3">&</span> fs<span class="sy4">::</span><span class="me2">perms</span><span class="sy4">::</span><span class="me2">others_exec</span><span class="br0">)</span> <span class="sy3">!</span><span class="sy1">=</span> fs<span class="sy4">::</span><span class="me2">perms</span><span class="sy4">::</span><span class="me2">none</span> <span class="sy4">?</span> <span class="st0">"x"</span> <span class="sy4">:</span> <span class="st0">"-"</span><span class="br0">)</span>
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<span class="sy1"><<</span> <span class="st0">'<span class="es1">\n</span>'</span><span class="sy4">;</span>
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<span class="br0">}</span>
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<span class="kw4">int</span> main<span class="br0">(</span><span class="br0">)</span>
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<span class="br0">{</span>
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<a href="cpp-io-basic_ofstream.html"><span class="kw1733">std::<span class="me2">ofstream</span></span></a><span class="br0">(</span><span class="st0">"test.txt"</span><span class="br0">)</span><span class="sy4">;</span> <span class="co1">// 创建文件</span>
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<a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> <span class="st0">"Created file with permissions: "</span><span class="sy4">;</span>
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demo_perms<span class="br0">(</span>fs<span class="sy4">::</span><span class="me2">status</span><span class="br0">(</span><span class="st0">"test.txt"</span><span class="br0">)</span>.<span class="me1">permissions</span><span class="br0">(</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span>
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fs<span class="sy4">::</span><span class="me2">permissions</span><span class="br0">(</span><span class="st0">"test.txt"</span>,
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fs<span class="sy4">::</span><span class="me2">perms</span><span class="sy4">::</span><span class="me2">owner_all</span> <span class="sy3">|</span> fs<span class="sy4">::</span><span class="me2">perms</span><span class="sy4">::</span><span class="me2">group_all</span>,
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fs<span class="sy4">::</span><span class="me2">perm_options</span><span class="sy4">::</span><span class="me2">add</span><span class="br0">)</span><span class="sy4">;</span>
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<a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> <span class="st0">"After adding o+rwx and g+rwx: "</span><span class="sy4">;</span>
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demo_perms<span class="br0">(</span>fs<span class="sy4">::</span><span class="me2">status</span><span class="br0">(</span><span class="st0">"test.txt"</span><span class="br0">)</span>.<span class="me1">permissions</span><span class="br0">(</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span>
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fs<span class="sy4">::</span><span class="me2">remove</span><span class="br0">(</span><span class="st0">"test.txt"</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="br0">}</span></pre></div>
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</div>
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<p>可能的输出：</p>
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<div dir="ltr" class="mw-geshi" style="text-align: left;">
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<div class="text source-text">
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<pre class="de1">Created file with permissions: rw-r--r--
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After adding o+rwx and g+wrx: rwxrwxr--</pre></div>
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</div>
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</div>
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<h3><span class="mw-headline" id=".E5.8F.82.E9.98.85">参阅</span></h3>
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<table class="t-dsc-begin">
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<tr class="t-dsc">
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<td>
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<div class="t-dsc-member-div">
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<div><a href="cpp-filesystem-permissions.html"><span class="t-lines"><span>permissions</span></span></a></div>
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<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx17">(C++17)</span></span></span></div>
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</div>
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</td>
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<td>修改文件访问权限<br />
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<span class="t-mark">(函数)</span></td>
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</tr>
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<tr class="t-dsc">
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<td>
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<div class="t-dsc-member-div">
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<div><a href="cpp-filesystem-perms.html"><span class="t-lines"><span>perms</span></span></a></div>
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<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx17">(C++17)</span></span></span></div>
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</div>
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</td>
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<td>标识文件系统权限<br />
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<span class="t-mark">(枚举)</span></td>
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</tr>
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</table>
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</div>
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<div class="visualClear"></div>
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</div>
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</div>
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</div>
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</body>
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