A low-level, C-callable interface is provided to mount a file system.
That interface is called <code>mount()</code> and is mentioned in the <ahref="NuttxPortingGuide.html#NxFileSystem"><code>porting guide</code></a> and is prototyped in the header file <code>include/sys/mount.h</code>:
</p>
<ul><pre>
int mount(const char *source, const char *target, const char *filesystemtype, unsigned long mountflags, const void *data);
</pre></ul>
<p>
<b>Synopsis</b>:
<code>mount()</code> attaches the filesystem specified by the <code>source</code> block device name into the root file system at the path specified by <code>target</code>.
</p>
<p>
<b>Input Paramters</b>:
<ul>
<li><code>source</code>. A null-terminated string providing the fill path to a block driver in the NuttX pseudo-file system.
<li><code>target</code>. The location in the NuttX pseudo-file system where the volume will be mounted.
<li><code>filesystemtype</code>. A string identifying the type of file system to use.
<li><code>mountflags</code>. Various flags that can be used to qualify how the file system is mounted.
<li><code>data</code>. Opaque data that is passed to the file system with the mount occurs.
</ul>
</p>
<p>
<b>Returned Values</b>
Zero is returned on success; -1 is returned on an error and <code>errno</code> is set appropriately:
<ul>
<li><code>EACCES</code>.
A component of a path was not searchable or mounting a read-onlyfilesystem was attempted without giving the <code>MS_RDONLY</code> flag.
</li>
<li><code>EBUSY</code>.
<code>source</code> is already mounted.
</li>
<li><code>EFAULT</code>.
One of the pointer arguments points outside the user address space.
</li>
<li><code>EINVAL</code>.
<code>source</code> had an invalid superblock.
</li>
<li><code>ENODEV</code>.
<code>filesystemtype</code> not configured
</li>
<li><code>ENOENT</code>.
A pathname was empty or had a nonexistent component.
</li>
<li><code>ENOMEM</code>.
Could not allocate a memory to copy filenames or data into.
</li>
<li><code>ENOTBLK</code>.
<code>source</code> is not a block device
</li>
</ul>
</p>
<p>
This same interface can be used to mount a remote, NFS file system using some special parameters.
The NFS mount differs from the <i>normal</i> file system mount in that: (1) there is no block driver for the NFS file system, and (2) special parameters must be passed as <code>data</code> to describe the remote NFS server.
Thus the following code snippet might represent how an NFS file system is mounted:
</p>
<ul><pre>
#include <sys/mount.h>
#include <nuttx/fs/nfs.h>
struct nfs_args data;
char *mountpoint;
ret = mount(NULL, mountpoint, string "nfs", 0, (FAR void *)&data);
It is important that <code>/export</code> directory allow access to everyone (777 permissions) as we will be accessing the NFS share from the client with no authentication.
When all this is done, we will need to edit the configuration file to set up an NFS server: <code>/etc/exports</code>.
This file contains a list of entries;
each entry indicates a volume that is shared and how it is shared.
For more information for a complete description of all the setup options for this file you can check in the man pages (<code>man export</code>).</p>
An entry in <code>/etc/exports</code> will typically look like this:
</p>
<ul><pre>
directory machine1(option11,option12)
</pre></ul>
<p>
So for our example we export <coce>/export</code> to the client 10.0.0.2 add the entry:
</p>
<ul><pre>
/export 10.0.0.2(rw)
</pre></ul>
<p>
In our case we are using all the default options except for the <code>ro</code> that we replaced with <code>rw</code> so that our client will have read and write access to the directory that we are exporting.
