curl - Internal Design

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <title>curl - Internal Design</title> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <meta content="text/html; charset=UTF-8" http-equiv="Content-Type"> <link rel="stylesheet" type="text/css" href="/curl.css"> <link rel="shortcut icon" href="/favicon.ico"> <link rel="icon" href="/logo/curl-symbol.svg" type="image/svg+xml"> <link rel="alternate" type="application/rss+xml" title="cURL Releases" href="https://github.com/curl/curl/releases.atom"> </head> <body> <div class="main"> <div class="menu"> <div class="dropdown"> <a class="dropbtn" href="/dev/">Dev-related docs</a> <div class="dropdown-content"> <a href="/dev/code-review.html">Code Review</a> <a href="/dev/code-style.html">Code Style</a> <a href="/dev/contribute.html">Contribute</a> <a href="/dev/deprecate.html">Deprecate</a> <a href="/dev/internals.html">Internals</a> <a href="/dev/new-protocol.html">New protocol</a> <a href="/dev/release-procedure.html">Release procedure</a> <a href="/dev/roadmap.html">Roadmap</a> <a href="/dev/runtests.html">Run tests</a> <a href="/dev/source.html">Source code</a> <a href="/rfc/">Specifications</a> <a href="https://testclutch.curl.se/">Test Clutch</a> <a href="/dev/testcurl.html">Test curl</a> <a href="/dev/test-fileformat.html">Test case file format</a> <a href="/dev/tests-overview.html">Tests Overview</a> <a href="/dev/vuln-disclosure.html">Vulnerability Disclosure Policy</a> </div> </div> <div class="dropdown"> <a class="dropbtn" href="/dev/./">Current status</a> <div class="dropdown-content"> <a href="/dev/builds.html">Autobuilds</a> <a href="/snapshots/">Daily snapshots</a> <a href="/dashboard.html">Dashboard</a> <a href="/dev/feature-window.html">Feature window</a> <a href="/gitstats/">git stats</a> <a href="https://github.com/curl/curl/issues" target="_blank">Issues (github)</a> <a href="https://github.com/curl/curl/pulls" target="_blank">Pull requests (github)</a> <a href="/dev/release-notes.html">Release Notes</a> </div> </div> </div> <div class="contents"> <div class="where"><a href="/">curl</a> / <a href="/dev/">Development</a> / <b>Internals</b></div> <div class="relatedbox"> <b>Related:</b> <br><a href="/docs/">Documentation Overview</a> <br><a href="source.html">Source code</a> </div>  <h1 id="curl-internals">curl internals</h1> <p>The canonical libcurl internals documentation is now in the <a href="https://everything.curl.dev/internals">everything curl</a> book. This file lists supported versions of libs and build tools.</p> <h2 id="portability">Portability</h2> <p>We write curl and libcurl to compile with C89 compilers on 32-bit and up machines. Most of libcurl assumes more or less POSIX compliance but that is not a requirement.</p> <p>We write libcurl to build and work with lots of third party tools, and we want it to remain functional and buildable with these and later versions (older versions may still work but is not what we work hard to maintain):</p> <h2 id="dependencies">Dependencies</h2> <p>We aim to support these or later versions.</p> <ul> <li>OpenSSL 0.9.7</li> <li>GnuTLS 3.1.10</li> <li>zlib 1.1.4</li> <li>libssh2 1.0</li> <li>c-ares 1.16.0</li> <li>libidn2 2.0.0</li> <li>wolfSSL 2.0.0</li> <li>OpenLDAP 2.0</li> <li>MIT Kerberos 1.2.4</li> <li>Heimdal ?</li> <li>nghttp2 1.15.0</li> <li>Winsock 2.2 (on Windows 95+ and Windows CE .NET 4.1+)</li> </ul> <h2 id="build-tools">Build tools</h2> <p>When writing code (mostly for generating stuff included in release tarballs) we use a few "build tools" and we make sure that we remain functional with these versions:</p> <ul> <li>GNU Libtool 1.4.2</li> <li>GNU Autoconf 2.59</li> <li>GNU Automake 1.7</li> <li>GNU M4 1.4</li> <li>perl 5.8</li> <li>roffit 0.5</li> <li>cmake 3.7</li> </ul> <h1 id="library-symbols">Library Symbols</h1> <p>All symbols used internally in libcurl must use a <code>Curl_</code> prefix if they are used in more than a single file. Single-file symbols must be made static. Public ("exported") symbols must use a <code>curl_</code> prefix. Public API functions are marked with <code>CURL_EXTERN</code> in the public header files so that all others can be hidden on platforms where this is possible.</p> </div> </div> </body> </html>

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curl - Internal Design