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diff --git a/public/build-bash-1.html b/public/build-bash-1.html new file mode 100644 index 0000000..d1494fd --- /dev/null +++ b/public/build-bash-1.html @@ -0,0 +1,110 @@ +<!DOCTYPE html> +<html lang="en"> +<head> + <meta charset="utf-8"> + <title>Building Bash 1.14.7 on a modern system — Luke T. Shumaker</title> + <meta name="viewport" content="width=device-width, initial-scale=1"> + <link rel="stylesheet" href="assets/style.css"> + <link rel="alternate" type="application/atom+xml" href="./index.atom" name="web log entries"/> +</head> +<body> +<header><a href="/">Luke T. Shumaker</a> » <a href=/blog>blog</a> » build-bash-1</header> +<article> +<h1 id="building-bash-1.14.7-on-a-modern-system">Building Bash 1.14.7 on +a modern system</h1> +<p>In a previous revision of my <a href="./bash-arrays.html">Bash arrays +post</a>, I wrote:</p> +<blockquote> +<p>Bash 1.x won’t compile with modern GCC, so I couldn’t verify how it +behaves.</p> +</blockquote> +<p>I recall spending a little time fighting with it, but apparently I +didn’t try very hard: getting Bash 1.14.7 to build on a modern box is +mostly just adjusting it to use <code>stdarg</code> instead of the +no-longer-implemented <code>varargs</code>. There’s also a little +fiddling with the pre-autoconf automatic configuration.</p> +<h2 id="stdarg">stdarg</h2> +<p>Converting to <code>stdarg</code> is pretty simple: For each variadic +function (functions that take a variable number of arguments), follow +these steps:</p> +<ol type="1"> +<li>Replace <code>#include <varargs.h></code> with +<code>#include <stdarg.h></code></li> +<li>Replace <code>function_name (va_alist) va_dcl</code> with +<code>function_name (char *format, ...)</code>.</li> +<li>Removing the declaration and assignment for <code>format</code> from +the function body.</li> +<li>Replace <code>va_start (args);</code> with +<code>va_start (args, format);</code> in the function bodies.</li> +<li>Replace <code>function_name ();</code> with +<code>function_name (char *, ...)</code> in header files and/or at the +top of C files.</li> +</ol> +<p>There’s one function that uses the variable name <code>control</code> +instead of <code>format</code>.</p> +<p>I’ve prepared <a href="./bash-1.14.7-gcc4-stdarg.patch">a patch</a> +that does this.</p> +<h2 id="configuration">Configuration</h2> +<p>Instead of using autoconf-style tests to test for compiler and +platform features, Bash 1 used the file <code>machines.h</code> that had +<code>#ifdefs</code> and a huge database of of different operating +systems for different platforms. It’s gross. And quite likely won’t +handle your modern operating system.</p> +<p>I made these two small changes to <code>machines.h</code> to get it +to work correctly on my box:</p> +<ol type="1"> +<li>Replace <code>#if defined (i386)</code> with +<code>#if defined (i386) || defined (__x86_64__)</code>. The purpose of +this is obvious.</li> +<li>Add <code>#define USE_TERMCAP_EMULATION</code> to the section for +Linux [sic] on i386 +(<code># if !defined (done386) && (defined (__linux__) || defined (linux))</code>). +What this does is tell it to link against libcurses to use curses +termcap emulation, instead of linking against libtermcap (which doesn’t +exist on modern GNU/Linux systems).</li> +</ol> +<p>Again, I’ve prepared <a href="./bash-1.14.7-machines-config.patch">a +patch</a> that does this.</p> +<h2 id="building">Building</h2> +<p>With those adjustments, it should build, but with quite a few +warnings. Making a couple of changes to <code>CFLAGS</code> should fix +that:</p> +<pre><code>make CFLAGS='-O -g -Werror -Wno-int-to-pointer-cast -Wno-pointer-to-int-cast -Wno-deprecated-declarations -include stdio.h -include stdlib.h -include string.h -Dexp2=bash_exp2'</code></pre> +<p>That’s a doozy! Let’s break it down:</p> +<ul> +<li><code>-O -g</code> The default value for CFLAGS (defined in +<code>cpp-Makefile</code>)</li> +<li><code>-Werror</code> Treat warnings as errors; force us to deal with +any issues.</li> +<li><code>-Wno-int-to-pointer-cast -Wno-pointer-to-int-cast</code> Allow +casting between integers and pointers. Unfortunately, the way this +version of Bash was designed requires this.</li> +<li><code>-Wno-deprecated-declarations</code> The <code>getwd</code> +function in <code>unistd.h</code> is considered deprecated (use +<code>getcwd</code> instead). However, if <code>getcwd</code> is +available, Bash uses it’s own <code>getwd</code> wrapper around +<code>getcwd</code> (implemented in <code>general.c</code>), and only +uses the signature from <code>unistd.h</code>, not the actuall +implementation from libc.</li> +<li><code>-include stdio.h -include stdlib.h -include string.h</code> +Several files are missing these header file includes. If not for +<code>-Werror</code>, the default function signature fallbacks would +work.</li> +<li><code>-Dexp2=bash_exp2</code> Avoid a conflict between the parser’s +<code>exp2</code> helper function and <code>math.h</code>’s base-2 +exponential function.</li> +</ul> +<p>Have fun, software archaeologists!</p> + +</article> +<footer> + <aside class="sponsor"><p>I'd love it if you <a class="em" + href="/sponsor/">sponsored me</a>. It will allow me to continue + <a class="em" href="/imworkingon/">my work</a> on the GNU/Linux + ecosystem. Thanks!</p></aside> + +<p>The content of this page is Copyright © 2015 <a href="mailto:lukeshu@lukeshu.com">Luke T. Shumaker</a>.</p> +<p>This page is licensed under the <a href="https://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA 4.0</a> license.</p> +</footer> +</body> +</html> |