[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Changes to html_node/Known-Bugs.html

From: Jim Meyering
Subject: Changes to html_node/Known-Bugs.html
Date: Thu, 2 Jan 2020 18:18:46 -0500 (EST)

CVSROOT:        /webcvs/grep
Module name:    grep
Changes by:     Jim Meyering <meyering> 20/01/02 18:18:45

Index: html_node/Known-Bugs.html
RCS file: html_node/Known-Bugs.html
diff -N html_node/Known-Bugs.html
--- /dev/null   1 Jan 1970 00:00:00 -0000
+++ html_node/Known-Bugs.html   2 Jan 2020 23:18:44 -0000       1.1
@@ -0,0 +1,96 @@
+<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" 
+<!-- This manual is for grep, a pattern matching engine.
+Copyright (C) 1999-2002, 2005, 2008-2020 Free Software Foundation,
+Permission is granted to copy, distribute and/or modify this document
+under the terms of the GNU Free Documentation License, Version 1.3 or
+any later version published by the Free Software Foundation; with no
+Invariant Sections, with no Front-Cover Texts, and with no Back-Cover
+Texts.  A copy of the license is included in the section entitled
+"GNU Free Documentation License". -->
+<!-- Created by GNU Texinfo 6.5, -->
+<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
+<title>Known Bugs (GNU Grep 3.4)</title>
+<meta name="description" content="Known Bugs (GNU Grep 3.4)">
+<meta name="keywords" content="Known Bugs (GNU Grep 3.4)">
+<meta name="resource-type" content="document">
+<meta name="distribution" content="global">
+<meta name="Generator" content="makeinfo">
+<link href="index.html#Top" rel="start" title="Top">
+<link href="Index.html#Index" rel="index" title="Index">
+<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
+<link href="Reporting-Bugs.html#Reporting-Bugs" rel="up" title="Reporting 
+<link href="Copying.html#Copying" rel="next" title="Copying">
+<link href="Reporting-Bugs.html#Reporting-Bugs" rel="prev" title="Reporting 
+<style type="text/css">
+a.summary-letter {text-decoration: none}
+blockquote.indentedblock {margin-right: 0em}
+blockquote.smallindentedblock {margin-right: 0em; font-size: smaller}
+blockquote.smallquotation {font-size: smaller}
+div.display {margin-left: 3.2em}
+div.example {margin-left: 3.2em}
+div.lisp {margin-left: 3.2em}
+div.smalldisplay {margin-left: 3.2em}
+div.smallexample {margin-left: 3.2em}
+div.smalllisp {margin-left: 3.2em}
+kbd {font-style: oblique}
+pre.display {font-family: inherit}
+pre.format {font-family: inherit} {font-family: serif} {font-family: serif}
+pre.smalldisplay {font-family: inherit; font-size: smaller}
+pre.smallexample {font-size: smaller}
+pre.smallformat {font-family: inherit; font-size: smaller}
+pre.smalllisp {font-size: smaller}
+span.nolinebreak {white-space: nowrap}
+span.roman {font-family: initial; font-weight: normal}
+span.sansserif {font-family: sans-serif; font-weight: normal} {list-style: none}
+<link rel="stylesheet" type="text/css" href="/software/gnulib/manual.css">
+<body lang="en">
+<a name="Known-Bugs"></a>
+<div class="header">
+Up: <a href="Reporting-Bugs.html#Reporting-Bugs" accesskey="u" 
rel="up">Reporting Bugs</a> &nbsp; [<a href="index.html#SEC_Contents" 
title="Table of contents" rel="contents">Contents</a>][<a 
href="Index.html#Index" title="Index" rel="index">Index</a>]</p>
+<a name="Known-Bugs-1"></a>
+<h3 class="section">6.1 Known Bugs</h3>
+<a name="index-Bugs_002c-known"></a>
+<p>Large repetition counts in the &lsquo;<samp>{n,m}</samp>&rsquo; construct 
may cause
+<code>grep</code> to use lots of memory.
+In addition, certain other
+obscure regular expressions require exponential time and
+space, and may cause <code>grep</code> to run out of memory.
+<p>Back-references can greatly slow down matching, as they can generate
+exponentially many matching possibilities that can consume both time
+and memory to explore.  Also, the POSIX specification for
+back-references is at times unclear.  Furthermore, many regular
+expression implementations have back-reference bugs that can cause
+programs to return incorrect answers or even crash, and fixing these
+bugs has often been low-priority&mdash;for example, as of 2019 the GNU C
+library bug database contained back-reference bugs 52, 10844, 11053,
+and 25322, with little sign of forthcoming fixes.  Luckily,
+back-references are rarely useful and it should be little trouble to
+avoid them in practical applications.

reply via email to

[Prev in Thread] Current Thread [Next in Thread]