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diff --git a/static/freebsd/man4/fdescfs.4 3.html b/static/freebsd/man4/fdescfs.4 3.html new file mode 100644 index 00000000..9e0f124a --- /dev/null +++ b/static/freebsd/man4/fdescfs.4 3.html @@ -0,0 +1,141 @@ +<table class="head"> + <tr> + <td class="head-ltitle">FDESCFS(4)</td> + <td class="head-vol">Device Drivers Manual</td> + <td class="head-rtitle">FDESCFS(4)</td> + </tr> +</table> +<div class="manual-text"> +<section class="Sh"> +<h1 class="Sh" id="NAME"><a class="permalink" href="#NAME">NAME</a></h1> +<p class="Pp"><code class="Nm">fdescfs</code> — + <span class="Nd">file-descriptor file system</span></p> +</section> +<section class="Sh"> +<h1 class="Sh" id="SYNOPSIS"><a class="permalink" href="#SYNOPSIS">SYNOPSIS</a></h1> +<div class="Bd Li"> +<pre>fdescfs /dev/fd fdescfs rw 0 0</pre> +</div> +</section> +<section class="Sh"> +<h1 class="Sh" id="DESCRIPTION"><a class="permalink" href="#DESCRIPTION">DESCRIPTION</a></h1> +<p class="Pp">The file-descriptor file system, or + <code class="Nm">fdescfs</code>, provides access to the per-process file + descriptor namespace in the global file system namespace. The conventional + mount point is <span class="Pa">/dev/fd</span>.</p> +<p class="Pp">The file system's contents appear as a list of numbered files + which correspond to the open files of the process reading the directory. The + files <span class="Pa">/dev/fd/0</span> through + <span class="Pa">/dev/fd/#</span> refer to file descriptors which can be + accessed through the file system.</p> +<p class="Pp">The following mount options can be used when mounting + <code class="Nm">fdescfs</code> filesystem:</p> +<dl class="Bl-tag"> + <dt id="nodup"><a class="permalink" href="#nodup"><code class="Cm">nodup</code></a></dt> + <dd>For file descriptors referencing vnodes, instead of the + <a class="Xr">dup(2)</a> semantic described above, implement re-opening of + the referenced vnode. See below for more details.</dd> + <dt id="linrdlnk"><a class="permalink" href="#linrdlnk"><code class="Cm">linrdlnk</code></a></dt> + <dd>Report the type of the <code class="Nm">fdescfs</code> vnode as + <code class="Dv">VLNK</code> instead of <span class="Ux">FreeBSD</span> + traditional <code class="Dv">VCHR</code>. For <a class="Xr">linux(4)</a> + ABI compatibility mount <code class="Nm">fdescfs</code> volume with the + <code class="Cm">linrdlnk</code> option.</dd> + <dt id="rdlnk"><a class="permalink" href="#rdlnk"><code class="Cm">rdlnk</code></a></dt> + <dd>Treat <code class="Nm">fdescfs</code> vnodes as symbolic links + consistently, in particular, follow the resolved name for the name + lookups. This option is strictly stronger than the + <code class="Cm">linrdlnk</code> option, it changes not only the type + returned by <a class="Xr">stat(2)</a>, but also causes the + <code class="Nm">fdescfs</code> files to behave as symlinks.</dd> +</dl> +<p class="Pp">For <code class="Nm">fdescfs</code> mounted without the + <code class="Cm">nodup</code> mount option, if the file descriptor is open + and the mode the file is being opened with is a subset of the mode of the + existing descriptor, the call:</p> +<div class="Bd Pp Bd-indent Li"> +<pre>fd = open("/dev/fd/0", mode);</pre> +</div> +<p class="Pp">and the call:</p> +<div class="Bd Pp Bd-indent Li"> +<pre>fd = fcntl(0, F_DUPFD, 0);</pre> +</div> +<p class="Pp">are equivalent. Flags to the <a class="Xr">open(2)</a> call other + than <code class="Dv">O_RDONLY</code>, <code class="Dv">O_WRONLY</code> and + <code class="Dv">O_RDWR</code> are ignored.</p> +<p class="Pp">For <code class="Nm">fdescfs</code> mounted with the + <code class="Cm">nodup</code> option, and file descriptor referencing a + vnode, the call:</p> +<div class="Bd Pp Bd-indent Li"> +<pre>fd = open("/dev/fd/0", mode);</pre> +</div> +<p class="Pp" id="open">reopens the referenced vnode with the specified + <var class="Fa">mode</var>. In other words, the + <a class="permalink" href="#open"><code class="Fn">open</code></a>() call + above is equivalent to</p> +<div class="Bd Pp Bd-indent Li"> +<pre>fd = openat(0, "", O_EMPTY_PATH, mode);</pre> +</div> +<p class="Pp" id="open~2">In particular, if the file descriptor was opened with + the <code class="Dv">O_PATH</code> flag, then either + <code class="Dv">O_EMPTY_PATH</code> or + <a class="permalink" href="#open~2"><code class="Fn">open</code></a>() over + <code class="Nm">fdescfs</code> mount with <code class="Cm">nodup</code> + option allows one to convert it to a regularly opened file, assuming that + the current permissions allow the requested <var class="Fa">mode</var>.</p> +<p class="Pp" id="Note:"><a class="permalink" href="#Note:"><i class="Em">Note:</i></a> + <span class="Pa">/dev/fd/0</span>, <span class="Pa">/dev/fd/1</span> and + <span class="Pa">/dev/fd/2</span> files are created by default when devfs + alone is mounted. <code class="Nm">fdescfs</code> creates entries for all + file descriptors opened by the process.</p> +</section> +<section class="Sh"> +<h1 class="Sh" id="FILES"><a class="permalink" href="#FILES">FILES</a></h1> +<dl class="Bl-tag Bl-compact"> + <dt><span class="Pa">/dev/fd/#</span></dt> + <dd style="width: auto;"> </dd> +</dl> +</section> +<section class="Sh"> +<h1 class="Sh" id="EXAMPLES"><a class="permalink" href="#EXAMPLES">EXAMPLES</a></h1> +<p class="Pp">To mount a <code class="Nm">fdescfs</code> volume located on + <span class="Pa">/dev/fd</span>:</p> +<p class="Pp"></p> +<div class="Bd Bd-indent"><code class="Li">mount -t fdescfs none + /dev/fd</code></div> +<p class="Pp">For <a class="Xr">linux(4)</a> ABI compatibility:</p> +<p class="Pp"></p> +<div class="Bd Bd-indent"><code class="Li">mount -t fdescfs -o linrdlnk none + /compat/linux/dev/fd</code></div> +<p class="Pp">For substitute of <code class="Dv">O_EMPTY_PATH</code> flag + use:</p> +<p class="Pp"></p> +<div class="Bd Bd-indent"><code class="Li">mount -t fdescfs -o nodup none + /dev/fdpath</code></div> +</section> +<section class="Sh"> +<h1 class="Sh" id="SEE_ALSO"><a class="permalink" href="#SEE_ALSO">SEE + ALSO</a></h1> +<p class="Pp"><a class="Xr">devfs(4)</a>, <a class="Xr">mount(8)</a></p> +</section> +<section class="Sh"> +<h1 class="Sh" id="HISTORY"><a class="permalink" href="#HISTORY">HISTORY</a></h1> +<p class="Pp">The <code class="Nm">fdescfs</code> file system first appeared in + <span class="Ux">4.4BSD</span>. The <code class="Nm">fdescfs</code> manual + page first appeared in <span class="Ux">FreeBSD 2.2</span>.</p> +</section> +<section class="Sh"> +<h1 class="Sh" id="AUTHORS"><a class="permalink" href="#AUTHORS">AUTHORS</a></h1> +<p class="Pp">The <code class="Nm">fdescfs</code> manual page was written by + <span class="An">Mike Pritchard</span> + <<a class="Mt" href="mailto:mpp@FreeBSD.org">mpp@FreeBSD.org</a>>, and + was based on the manual page written by <span class="An">Jan-Simon + Pendry</span>.</p> +</section> +</div> +<table class="foot"> + <tr> + <td class="foot-date">July 11, 2023</td> + <td class="foot-os">FreeBSD 15.0</td> + </tr> +</table> |