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<HTML><!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><!-- Created on September, 12 2004 by texi2html 1.64 --><!-- Written by: Lionel Cons <Lionel.Cons@cern.ch> (original author) Karl Berry <karl@freefriends.org> Olaf Bachmann <obachman@mathematik.uni-kl.de> and many others.Maintained by: Olaf Bachmann <obachman@mathematik.uni-kl.de>Send bugs and suggestions to <texi2html@mathematik.uni-kl.de> --><HEAD><TITLE>Autoconf, Automake, and Libtool: Memory Management</TITLE><META NAME="description" CONTENT="Autoconf, Automake, and Libtool: Memory Management"><META NAME="keywords" CONTENT="Autoconf, Automake, and Libtool: Memory Management"><META NAME="resource-type" CONTENT="document"><META NAME="distribution" CONTENT="global"><META NAME="Generator" CONTENT="texi2html 1.64"><script language="Javascript"><!-- // Check the browser version. function checkVersion() { if (navigator.appVersion.charAt(0)>=3) return true; if (navigator.appVersion.charAt(0)>=4) return true; else return false; 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By doing this, the rest of the project isrelieved of having to remember to check for <SAMP>`NULL'</SAMP> returns from thevarious memory functions. These wrappers use the <CODE>error</CODE> APIto report memory exhaustion and abort the program. I have placed theimplementation code in <TT>`xmalloc.c'</TT>:</P><P><TABLE width=100%><tr><td> </td><td class=example bgcolor=#6688aa><br><pre></pre></td></tr></table></P><P>Notice in the code above, that <CODE>xcalloc</CODE> is implemented in terms of<CODE>xmalloc</CODE>, since <CODE>calloc</CODE> itself is not available in someolder C libraries. Also, the <CODE>bzero</CODE> function is actuallydeprecated in favour of <CODE>memset</CODE> in modern C libraries --I'll explain how to take this into account later in <A HREF="autobook_62.html#SEC62">9.2.3 Beginnings of a <TT>`configure.in'</TT></A>.</P><P>Rather than create a separate <TT>`xmalloc.h'</TT> file, which would need tobe <CODE>#include</CODE>d from almost everywhere else, the logical place todeclare these functions is in <TT>`common.h'</TT>, since the wrappers willbe called from most everywhere else in the code:</P><P><TABLE width=100%><tr><td> </td><td class=example bgcolor=#6688aa><br><pre></pre></td></tr></table></P><P>By using the macros defined here, allocating and freeing heap memory isreduced from:</P><P><TABLE width=100%><tr><td> </td><td class=example bgcolor=#6688aa><br><pre>char **argv = (char **) xmalloc (sizeof (char *) * 3);do_stuff (argv);if (argv) free (argv);</pre></td></tr></table></P><P>to the simpler and more readable:</P><P><TABLE width=100%><tr><td> </td><td class=example bgcolor=#6688aa><br><pre>char **argv = XMALLOC (char *, 3);do_stuff (argv);XFREE (argv);</pre></td></tr></table></P><P>In the same spirit, I have borrowed <TT>`xstrdup.c'</TT> and<TT>`xstrerror.c'</TT> from project GNU's libiberty. See section <A HREF="autobook_50.html#SEC50">9.1.5 Fallback Function Implementations</A>.</P><P><A NAME="Generalised List Data Type"></A></TR></TABLE><BR> <FONT SIZE="-1">This document was generatedby <I>Gary V. Vaughan</I> on <I>September, 12 2004</I>using <A HREF="http://www.mathematik.uni-kl.de/~obachman/Texi2html"><I>texi2html</I></A></BODY></HTML>⌨️ 快捷键说明
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