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<h1> The <tt>buffer</tt> library interface </h1>
<p>
The following functions are declared in the <tt>skalibs/buffer.h</tt> header,
and implemented in the <tt>libskarnet.a</tt> or <tt>libskarnet.so</tt> library.
</p>
<h2> General information </h2>
<p>
skalibs provides convenience structures and functions to perform buffered I/O.
These structures and functions abstract direct calls to <tt>read</tt> or <tt>write</tt>;
they're meant to be used in place of <tt>stdio.h</tt> primitives. Unlike <tt>stdio</tt>,
they can be used with non-blocking file descriptors.
</p>
<p>
A buffer is a structure containing the following fields:
</p>
<ul>
<li> <em>op</em>: a pointer to a function performing I/O. This is the function
that will be called anytime the buffer needs to acquire (or flush) data to its
underlying fd. </li>
<li> <em>fd</em>: the fd from which data will be read or written. </li>
<li> <em>c</em>: a circular buffer used to store data. </li>
</ul>
<p>
Users should not need to interact directly with any of these fields. They are
initialized by <tt>buffer_init</tt> or <tt>BUFFER_INIT</tt>. Ulterior
interactions with the buffer should only be done with the various dedicated
functions.
</p>
<h2> Functions </h2>
<p>
<code> ssize_t buffer_put (buffer *b, char const *buf, size_t len) </code> <br />
Write the <em>len</em> bytes pointed to by <em>buf</em> to buffer <em>b</em>.
Returns the number of bytes written if it succeeds, or -1 and sets errno if it
fails.
</p>
<p>
<code> ssize_t buffer_puts (buffer *b, char const *s) </code> <br />
Write the string <em>s</em>, terminating nul-byte excepted, to buffer <em>b</em>.
Returns the number of bytes written if it succeeds, or -1 and sets errno if it
fails.
</p>
<p>
<code> int buffer_flush(buffer *b) </code> <br />
Flushes the buffer <em>b</em>.
Returns 1 if it succeeds, 0 and sets errno if it fails.
</p>
<p>
<code> ssize_t buffer_get (buffer *b, char *s, size_t len) </code> <br />
Read <em>len</em> bytes from buffer <em>b</em> and write them into <em>s</em>.
Retuns the number of bytes read if it succeeds, or -1 and sets errno if it
fails.
</p>
<p>
The above are the most important and fundamental functions for buffering.
Other functions can be found in the same header and their prototypes are
self-explaining. More may be documented here later.
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