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<title>bio</title>
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<link rev="made" href="mailto:root@localhost" />
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<!-- INDEX BEGIN -->
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<div name="index">
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<p><a name="__index__"></a></p>
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<ul>
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<li><a href="#name">NAME</a></li>
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<li><a href="#synopsis">SYNOPSIS</a></li>
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<li><a href="#description">DESCRIPTION</a></li>
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<li><a href="#examples">EXAMPLES</a></li>
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<li><a href="#see_also">SEE ALSO</a></li>
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<li><a href="#copyright">COPYRIGHT</a></li>
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<p>
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</p>
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<hr />
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<h1><a name="name">NAME</a></h1>
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<p>bio - Basic I/O abstraction</p>
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<p>
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</p>
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<hr />
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<h1><a name="synopsis">SYNOPSIS</a></h1>
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<pre>
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#include <openssl/bio.h></pre>
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<p>
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</p>
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<hr />
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<h1><a name="description">DESCRIPTION</a></h1>
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<p>A BIO is an I/O abstraction, it hides many of the underlying I/O
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details from an application. If an application uses a BIO for its
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I/O it can transparently handle SSL connections, unencrypted network
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connections and file I/O.</p>
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<p>There are two type of BIO, a source/sink BIO and a filter BIO.</p>
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<p>As its name implies a source/sink BIO is a source and/or sink of data,
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examples include a socket BIO and a file BIO.</p>
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<p>A filter BIO takes data from one BIO and passes it through to
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another, or the application. The data may be left unmodified (for
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example a message digest BIO) or translated (for example an
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encryption BIO). The effect of a filter BIO may change according
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to the I/O operation it is performing: for example an encryption
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BIO will encrypt data if it is being written to and decrypt data
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if it is being read from.</p>
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<p>BIOs can be joined together to form a chain (a single BIO is a chain
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with one component). A chain normally consist of one source/sink
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BIO and one or more filter BIOs. Data read from or written to the
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first BIO then traverses the chain to the end (normally a source/sink
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BIO).</p>
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<p>Some BIOs (such as memory BIOs) can be used immediately after calling
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<code>BIO_new()</code>. Others (such as file BIOs) need some additional initialization,
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and frequently a utility function exists to create and initialize such BIOs.</p>
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<p>If <code>BIO_free()</code> is called on a BIO chain it will only free one BIO resulting
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in a memory leak.</p>
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<p>Calling <code>BIO_free_all()</code> on a single BIO has the same effect as calling
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<code>BIO_free()</code> on it other than the discarded return value.</p>
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2020-03-02 12:19:21 -05:00
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<p>Normally the <strong>type</strong> argument is supplied by a function which returns a
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pointer to a BIO_METHOD. There is a naming convention for such functions:
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a source/sink BIO is normally called BIO_s_*() and a filter BIO
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BIO_f_*();</p>
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<p>
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</p>
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<hr />
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<h1><a name="examples">EXAMPLES</a></h1>
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<p>Create a memory BIO:</p>
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<pre>
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BIO *mem = BIO_new(BIO_s_mem());</pre>
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<p>
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</p>
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<hr />
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<h1><a name="see_also">SEE ALSO</a></h1>
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<p><em>BIO_ctrl(3)</em>,
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<em>BIO_f_base64(3)</em>, <em>BIO_f_buffer(3)</em>,
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<em>BIO_f_cipher(3)</em>, <em>BIO_f_md(3)</em>,
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<em>BIO_f_null(3)</em>, <em>BIO_f_ssl(3)</em>,
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<em>BIO_find_type(3)</em>, <em>BIO_new(3)</em>,
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<em>BIO_new_bio_pair(3)</em>,
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<em>BIO_push(3)</em>, <em>BIO_read_ex(3)</em>,
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<em>BIO_s_accept(3)</em>, <em>BIO_s_bio(3)</em>,
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<em>BIO_s_connect(3)</em>, <em>BIO_s_fd(3)</em>,
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<em>BIO_s_file(3)</em>, <em>BIO_s_mem(3)</em>,
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<em>BIO_s_null(3)</em>, <em>BIO_s_socket(3)</em>,
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<em>BIO_set_callback(3)</em>,
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<em>BIO_should_retry(3)</em></p>
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<p>
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</p>
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<hr />
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<h1><a name="copyright">COPYRIGHT</a></h1>
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2020-03-02 12:19:21 -05:00
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<p>Copyright 2000-2019 The OpenSSL Project Authors. All Rights Reserved.</p>
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<p>Licensed under the OpenSSL license (the "License"). You may not use
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2020-03-02 11:50:34 -05:00
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this file except in compliance with the License. You can obtain a copy
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in the file LICENSE in the source distribution or at
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<a href="https://www.openssl.org/source/license.html">https://www.openssl.org/source/license.html</a>.</p>
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