cgic 原代码，CGI（Common Gateway Interface）是一种用于在Web服务器和应用程序之间传输数据的标准

<h1>cgic 2.08: an ANSI C library for CGI Programming</h1> <h2>By <a href="http://boutell.dev">Thomas Boutell</a></h2> <blockquote> <strong>IMPORTANT NOTICES:</strong> <p> If you have CGIC 1.05 or earlier, you should upgrade to CGIC 1.07, or to CGIC 2.02 or better, in order to obtain important security fixes. <p> If you have CGIC 2.0 or CGIC 2.01 and you use the cgiCookie routines, you should upgrade to CGIC 2.02 or better, in order to obtain important security fixes. </blockquote> <h3>Table of Contents</h3> <ul> <li><a href="#credits">Credits and license terms</a> <li><a href="#whatsnew208">What's new in version XYZ of CGIC?</a> <li><a href="#whatis">What is cgic?</a> <li><a href="#obtain">Obtaining cgic</a> <li><a href="#build">Building and testing cgic: a sample application</a> <li><a href="#nocompile">What to do if it won't compile</a> <li><a href="#howto">How to write a cgic application</a> <li><a href="#images">How can I generate images from my cgic application?</a> <li><a href="#debug">CGI debugging features: using capture</a> <li><a href="#functions">cgic function reference</a> <li><a href="#variables">cgic variable reference</a> <li><a href="#resultcodes">cgic result code reference</a> <li><a href="#index">cgic quick index</a> </ul> <h3><a name="credits">Credits and License Terms</a></h3> <p> cgic is now distributed under the MIT license: </p> <p> Copyright (c) 1996-2020 Thomas Boutell </p> <p> Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: </p> <p> The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. </p> <p> THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. </p> <p> Thanks are due to Robert Gustavsson, Ken Holervich, Bob Nestor, Jon Ribbens, Thomas Strangert, Wu Yongwei, and other CGIC users who have corresponded over the years. Although the implementation of multipart/form-data file upload support in CGIC 2.x is my own, I particularly wish to thank those who submitted their own implementations of this feature. </p> <h3><a name="whatsnew208">What's new in version 2.08?</a></h3> Beginning with version 2.08, `cgic` offers more options when setting cookies. To enhance security, the following options can be used when setting a cookie: <ul> <li>Secure</li> <li>HttpOnly</li> <li>SameSite=Strict</li> </ul> The new function <code><a href="#cgiHeaderCookieSet">cgiHeaderCookieSet</a></code> allows you to set these options. The function <code><a href="#cgiHeaderCookieSetString">cgiHeaderCookieSetString</a></code> is kept for compability reasons. <h3><a name="whatsnew207">What's new in version 2.07?</a></h3> Per a suggestion by Geoff Mulligan, cgic now tolerates keys without a value in URL-encoded GET and POST submissions. Although the HTML5 spec discourages it, there are existing systems in the wild that do leave the `=` off entirely if the value is an empty string. Beginning with version 2.07, `cgic` handles this as you'd expect: you get an entry with the corresponding key and an empty string as the value. A simple unit test compilation target was also added, to test this feature and rule out side effects. <h3><a name="whatsnew206">What's new in version 2.06?</a></h3> A long list of significant fixes generously contributed by Jeffrey Hutzelman. <a href="https://github.com/boutell/cgic/commit/2065a2dfa480209bd6171acb2a4edd6e1c27a062"> These are especially important on platforms where attempting to read beyong the content length stated by the request can lead to a deadlock. Please see the commit notes.</a> <h3><a name="whatsnew205">What's new in version 2.05?</a></h3> Uploaded files properly closed; corrects a resource leak and enables file uploads to work properly on platforms with particular file locking semantics. <h3><a name="whatsnew204">What's new in version 2.04?</a></h3> Documentation fixes: the cgiHtmlEscape, cgiHtmlEscapeData, cgiValueEscape, and cgiValueEscapeData routines were named incorrectly in the manual. No code changes in version 2.04. <h3><a name="whatsnew203">What's new in version 2.03?</a></h3> <ul> <li>Support for setting cookies has been reimplemented. The new code closely follows the actual practice of web sites that successfully use cookies, rather than attempting to implement the specification. The new code can successfully set more than one cookie at a time in typical web browsers. </ul> <h3><a name="whatsnew202">What's new in version 2.02?</a></h3> <ul> <li>In CGIC 2.0 and 2.01, if the HTTP_COOKIE environment variable was exactly equal to the name of a cookie requested with cgiCookieString, with no value or equal sign or other characters present, a buffer overrun could take place. This was not normal behavior and it is unknown whether any actual web server would allow it to occur, however we have of course released a patch to correct it. Thanks to Nicolas Tomadakis. <li>cgiCookieString returned cgiFormTruncated when cgiFormSuccess would be appropriate. Fixed; thanks to Mathieu Villeneuve-Belair. <li>Cookies are now set using a simpler Set-Cookie: header, and with one header line per cookie, based on data collected by Chunfu Lai. <li>Memory leaks in cgiReadEnvironment fixed by Merezko Oleg. These memory leaks were <em>not</em> experienced in a normal CGI situation, only when reading a saved CGI environment. </ul> <h3><a name="whatsnew201">What's new in version 2.01?</a></h3> <ul> <li>Makefile supports "make install" <li>Compiles without warnings under both C and C++ with strict warnings and strict ANSI compliance enabled <li>Builds out of the box on Windows (#include &lt;fcntl.h&gt; was needed) <li>Rare problem in cgiReadEnvironment corrected; no impact on normal CGI operations <li>cgiCookieString now sets the result to an empty string when returning cgiFormNotFound <li>Minor code cleanups </ul> <h3><a name="whatsnew200">What's new in version 2.0?</a></h3> 1. CGIC 2.0 provides support for file upload fields. User-uploaded files are kept in temporary files, to avoid the use of excessive swap space (Solaris users may wish to change the <code>cgicTempDir</code> macro in cgic.c before compiling). The <code><a href="#cgiFormFileName">cgiFormFileName</a></code>, <code><a href="#cgiFormFileContentType">cgiFormFileContentType</a></code>, <code><a href="#cgiFormFileSize">cgiFormFileSize</a></code>, <code><a href="#cgiFormFileOpen">cgiFormFileOpen</a></code>, <code><a href="#cgiFormFileRead">cgiFormFileRead</a></code>, and <code><a href="#cgiFormFileClose">cgiFormFileClose</a></code> functions provide a complete interface to this new functionality. Remember, the <code>enctype</code> attribute of the <code>form</code> tag must be set to <code>multipart/form-data</code> when <code>&lt;input type="file"&gt;</code> tags are used. <p> 2. CGIC 2.0 provides support for setting and examining cookies (persistent data storage on the browser side). The <code><a href="#cgiCookieString">cgiCookieString</a></code>, and <code><a href="#cgiCookieInteger">cgiCookieInteger</a></code> and <code><a href="#cgiCookies">cgiCookies</a></code> functions retrieve cookies. The <code><a href="#cgiHeaderCookieSetString">cgiHeaderCookieSetString</a></code> and <code><a href="#cgiHeaderCookieSetIn