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<?xml version="1.0" ?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>CMS_compress</title> <meta http-equiv="content-type" content="text/html; charset=utf-8" /> <link rev="made" href="mailto:root@hsxx.drive.ne.jp" /> </head> <body style="background-color: white"> <!-- INDEX BEGIN --> <div name="index"> <p><a name="__index__"></a></p> <ul> <li><a href="#name">NAME</a></li> <li><a href="#synopsis">SYNOPSIS</a></li> <li><a href="#description">DESCRIPTION</a></li> <li><a href="#notes">NOTES</a></li> <li><a href="#notes">NOTES</a></li> <li><a href="#return_values">RETURN VALUES</a></li> <li><a href="#see_also">SEE ALSO</a></li> <li><a href="#history">HISTORY</a></li> <li><a href="#copyright">COPYRIGHT</a></li> </ul> <hr name="index" /> </div> <!-- INDEX END --> <p> </p> <hr /> <h1><a name="name">NAME</a></h1> <p>CMS_compress - create a CMS CompressedData structure</p> <p> </p> <hr /> <h1><a name="synopsis">SYNOPSIS</a></h1> <pre> #include <openssl/cms.h></pre> <pre> CMS_ContentInfo *CMS_compress(BIO *in, int comp_nid, unsigned int flags);</pre> <p> </p> <hr /> <h1><a name="description">DESCRIPTION</a></h1> <p><code>CMS_compress()</code> creates and returns a CMS CompressedData structure. <strong>comp_nid</strong> is the compression algorithm to use or <strong>NID_undef</strong> to use the default algorithm (zlib compression). <strong>in</strong> is the content to be compressed. <strong>flags</strong> is an optional set of flags.</p> <p> </p> <hr /> <h1><a name="notes">NOTES</a></h1> <p>The only currently supported compression algorithm is zlib using the NID NID_zlib_compression.</p> <p>If zlib support is not compiled into OpenSSL then <code>CMS_compress()</code> will return an error.</p> <p>If the <strong>CMS_TEXT</strong> flag is set MIME headers for type <strong>text/plain</strong> are prepended to the data.</p> <p>Normally the supplied content is translated into MIME canonical format (as required by the S/MIME specifications) if <strong>CMS_BINARY</strong> is set no translation occurs. This option should be used if the supplied data is in binary format otherwise the translation will corrupt it. If <strong>CMS_BINARY</strong> is set then <strong>CMS_TEXT</strong> is ignored.</p> <p>If the <strong>CMS_STREAM</strong> flag is set a partial <strong>CMS_ContentInfo</strong> structure is returned suitable for streaming I/O: no data is read from the BIO <strong>in</strong>.</p> <p>The compressed data is included in the CMS_ContentInfo structure, unless <strong>CMS_DETACHED</strong> is set in which case it is omitted. This is rarely used in practice and is not supported by <code>SMIME_write_CMS()</code>.</p> <p> </p> <hr /> <h1><a name="notes">NOTES</a></h1> <p>If the flag <strong>CMS_STREAM</strong> is set the returned <strong>CMS_ContentInfo</strong> structure is <strong>not</strong> complete and outputting its contents via a function that does not properly finalize the <strong>CMS_ContentInfo</strong> structure will give unpredictable results.</p> <p>Several functions including <code>SMIME_write_CMS()</code>, i2d_CMS_bio_stream(), <code>PEM_write_bio_CMS_stream()</code> finalize the structure. Alternatively finalization can be performed by obtaining the streaming ASN1 <strong>BIO</strong> directly using <code>BIO_new_CMS()</code>.</p> <p>Additional compression parameters such as the zlib compression level cannot currently be set.</p> <p> </p> <hr /> <h1><a name="return_values">RETURN VALUES</a></h1> <p><code>CMS_compress()</code> returns either a CMS_ContentInfo structure or NULL if an error occurred. The error can be obtained from <code>ERR_get_error(3)</code>.</p> <p> </p> <hr /> <h1><a name="see_also">SEE ALSO</a></h1> <p><em>ERR_get_error(3)</em>, <em>CMS_uncompress(3)</em></p> <p> </p> <hr /> <h1><a name="history">HISTORY</a></h1> <p>The <strong>CMS_STREAM</strong> flag was added in OpenSSL 1.0.0.</p> <p> </p> <hr /> <h1><a name="copyright">COPYRIGHT</a></h1> <p>Copyright 2008-2016 The OpenSSL Project Authors. All Rights Reserved.</p> <p>Licensed under the OpenSSL license (the "License"). You may not use this file except in compliance with the License. You can obtain a copy in the file LICENSE in the source distribution or at <a href="https://www.openssl.org/source/license.html">https://www.openssl.org/source/license.html</a>.</p> </body> </html>